• 대한전기학회
Mobile QR Code QR CODE : The Transactions of the Korean Institute of Electrical Engineers
  • COPE
  • kcse
  • 한국과학기술단체총연합회
  • 한국학술지인용색인
  • Scopus
  • crossref
  • orcid

제주계통을 위한 재생에너지 발전 공급능력 산정 방법에 관한 연구 Comparative Analysis of Effective Supply Capacity Estimation Methods for Renewable Energy Generation in the Jeju Island Power Systems


위영민(Young-Min Wi)

As the penetration rate of renewable energy resources increases, the estimation of the supply capability of renewable energy generators has become an important factor in power system planning and operation. This paper compares and analyzes the methods for estimating the supply capability of renewable energy generation, specifically the PPCF(Peak-Period Capacity Factor) and ELCC(Effective Load Carrying Capacity) methods, using the Jeju power system as a case study. It was found that the ELCC, which reflects the uncertainty of power generation facilities, provides a more conservative estimation of the supply capability of renewable energy generation compared to the PPCF. Furthermore, the study confirmed the influence of the output time difference among renewable energy generators on their supply capability. The results of this study are expected to be used as basic data for planning and operating the power systems in Jeju.

탄소중립 시나리오 분석을 위한 전력계통 해석에 관한 연구 Study On Power System Analysis for Net Zero Carbon Emission Scenario Analysis


김익재(Ik-Jae Kim) ; 최진영(Jin-Young Choi) ; 조윤성(Yoon-Sung Cho)

The policy of expanding energy conversion facilities, with a focus on renewable energy, to achieve Net Zero Carbon Emission is ongoing. In line with this, it is necessary to plan future power system configurations and conduct system analyses to reach Net Zero Carbon Emission by 2050. This study forecasts the electricity demand and the scale of facilities required to construct a Net Zero Carbon Emission power grid by 2050. In configuring this system, the study identifies and analyzes problems that may arise from the expansion of renewable energy facilities. Furthermore, it proposes the optimal configuration for the future system by enhancing the power system, ensuring efficient and effective progress towards achieving Net Zero Carbon Emission.

주파수응답 능력을 확보한 Power-to-Heat 설비의 대한민국 전력계통 계통주파수 기여도 분석 Frequency Response Capability by Power-to-Heat Facilities: Contribution to the Frequency Stability of Korea’s Power System


안상진(Sang-Jin Ahn) ; 김우중(Woo-Jung Kim) ; 이유석(Yu-Seok Lee) ; 전영환(Yeong-Han Chun)

In the Korea’s electric power market, combined heat and power plants participating as a rigid supply during the winter season, do not engage in automatic generation control and load-following operations due to equipment reliability issues. Therefore, investment in flexible resources is essential for stable grid operation. Power-to-Heat (P2H) technology, which links heat sector and electrical power sector, is gaining attention. P2H can consume over-generation of solar power during the daytime for thermal production, offering economic benefits to the heat sector. Additionally, it can contribute to grid flexibility by adjusting the input power of electric boilers according to system conditions. This paper utilizes a power system frequency dynamic model to simulate a simple electric boiler frequency response. It also analyzes the impact of introducing P2H technology on frequency stability, considering Korea's 2030 generation mix.

저압 배전망에 접속된 분산전원이 고객 전압 관리에 미치는 영향 분석 Analysis of the Impact of Distributed Power Connected to the Low Voltage Distribution Network on Customer Voltage Management


이해성(Hae-Sung Lee) ; 임한민(Han-Min Lim) ; 이병성(Byung-Sung Lee) ; 김동섭(Dong-Sub Kim)

Voltage control has become more complex as distributed energy resources or electrical vehicles increase, but voltage control is essential to continuously increase the amount of power distribution lines connected to distributed energy resources. In this paper, we perform voltage measurement data analysis through AMI(Advanced Metering Infrastructure) to prevent voltage quality degradation due to connections of distributed energy resources through appropriate voltage control and to find ways to maintain a certain level of voltage quality. Through the analysis, it is possible to identify the correlation and voltage level of voltage changes due to the connection of distributed energy resources. Because OLTC(On Load Tap Changer) enables voltage regulation and phase shifting by varying the transformer ratio under load without interruption, OLTC is a representative voltage control method. Therefore, we attempt to understand the effect of applying OLTC which are representative voltage control method and the voltage quality management effect of distributed energy resource connection lines through the analysis of voltage volatility correlation for distributed energy resources. In addition, we attempt to find an appropriate control method to maintain the voltage quality of distribution lines connected to distributed energy resources.

아파트 단일계약 전기 요금 분배 고찰: 협력 게임 이론적 접근 Consideration on Allocation of Electricity Cost in Apartments using Single Contract: A Cooperative Game Theory Approach


고갑석(Kabseok Ko) ; 백건(Keon Baek)

We address electricity cost allocation in high-voltage apartments under the single contract. In the contract, an apartment electricity cost depends significantly on the tier of usage averaged across households in the tiered pricing system. Individual cost may impact each other. To address this feature within allocation problems, we employ cooperative game theory. Specifically the Shapley value is adopted. On employing Shapley value, there are two problems: 1) linear relationship between household electricity cost and household usage, and 2) computation complexity. To address these problems, we propose an adjustment method for household electricity cost allocated according to Shapley value, and an approximate computation approach. This method incentivizes reduced power consumption by compensating low-usage households while charging higher costs to high-usage ones. Moreover, it enables high-usage households to benefit from lower rates compared to residential low-voltage contracts.

역전류 주입 토폴로지를 적용한 복합형 직류 차단기 제안 Proposal of Hybrid DC Circuit Breaker Applying Reverse Current Injection Topology


홍재영(Jae-Young Hong) ; 안태풍(Tae-Pung An)

In order to respond with the power consumption caused by the spread of eco-friendly vehicles and the expansion of data centers, it is necessary to increase the generation of new and renewable energy and provide stable power. In order that, it is necessary to configure a multi-terminal DC grid to effectively manage the AC/DC hybrid grid operation and the connection between the DC systems. DC circuit breaker that can be separated from the accident system is needed to minimize the impact at the fault and the stable operation of the multi-terminal DC grid. In this paper, we propose a hybrid DC circuit breaker that performs the blocking operation by creating a current zero crossing by injecting a reverse current. The current formula is explained through the order and analysis of the topology blocking operation. And the performance of the topology was verified by modeling and simulation the reverse current injection topology through PSCAD/EMTDC.

에너지 다소비 구역에 대한 연계선로 조류 계약 기반 계통연계형 지역단위 마이크로그리드의 최적설비계획 Optimal Planning of Gird-connected Regional Microgrid for Energy-intensive Areas Considering Interface Flow Contracts


송용현(Yong Hyun Song) ; 김승완(Seung Wan Kim)

The imperative installation of distributed energy resources to mitigate greenhouse gas emissions in the power sector has introduced operational challenges. In response, microgrids are emerging as a solution, signifying a transition from conventional centralized systems to regional self-sufficient decentralized energy systems. Within the context, this study proposes four contract types governing interface flows between main grid and microgrids to enhance system benefits through proactive operational integration with the primary system. Additionally, the study presents a methodological framework for optimal planning and cost estimation, incorporating mathematical optimization theory and the unique characteristics of each contract type. A case study, utilizing diverse datasets such as authentic load profiles, meteorological observations, and technical and cost parameters, reveals that optimal investments vary based on contract types on interface flows. Notably, it highlights that effectively managing volatility in the lower-level system, necessitates increased investments in flexibility resources. Furthermore, an analysis of facility investment changes based on the target energy self-sufficiency rate indicates a gradual increase in the allocation of flexibility resources as the self-sufficiency rate increases.

전기자동차용 150[kW] 구동 유닛의 설계 및 시험 검증 The Design and Verification of 150[kW] Drive Unit for EV


김희운(Hee-Woon Kim) ; 정채림(Chae-Lim Jeong)

In this paper, we summarize the finite element analysis results and experimental verification results of the electric motor of a 150 [kW] drive unit for electric vehicles. Analyze the no-load and load characteristics of electric motors and perform mechanical analysis at high speeds. To experimentally verify the drive unit, a coaxial reducer with the same motor output shaft and reducer output was designed and manufactured, and the experiment was conducted in accordance with the KS R 1203 standard. The design process of the drive unit for electric vehicles is verified through comparative analysis of analysis results and experimental results.

고속 회전체의 축방향 길이 최소화를 위한 자기베어링 설계 및 운전 Magnetic Bearing Design and Operation to Minimize the Axial Length of High-speed Rotor


박주홍(Joo-Hong Park) ; 노수진(Sujin Noh) ; 조한욱(Han-Wook Cho)

In this study, a fork-type heteropolar(FHP) magnetic bearing is proposed as an innovative advancement in magnetic bearing technology. The FHP magnetic bearing enhances winding density within the slot by positioning bobbins, and housing paired windings, side by side. In addition, a comparative analysis was conducted against the conventional heteropolar(CHP) magnetic bearing. The design of the FHP magnetic bearing optimizes the width of the magnetic pole surface by aligning it with the axis direction, enabling maximum force generation. Mathematical modeling and Campbell diagram analysis were employed to quantify the reduction in axial space achieved by the FHP magnetic bearing. Finite element analysis was performed to examine force characteristics and experimental verification confirmed the stability of the FHP magnetic bearing. Additionally, the FHP magnetic bearing was applied to an oil-free refrigerant compressor, validating its practical viability in industrial applications.

고주파 전류 성분의 주기성을 이용한 교류 아크 감지 기법 AC Arc Detection Method based on Periodicity of High-Frequency Current Components


김용헌(Yong-Heon Kim) ; 곽상신(Sang-Shin Kwak)

This paper presents an algorithm for detecting arcs by analyzing high-frequency signals of current. Series AC arcs were induced through experiments, capturing the current waveform during arc occurrences. In an AC system, arcs function akin to a switch, intermittently interrupting the circuit. The ignition and extinguishing phases of the arc generate periodic high-frequency component in the current, resulting from abrupt changes in its flow. Leveraging these distinctive features, this paper suggests an arc detection algorithm by scrutinizing the duration and occurrence intervals of high-frequency components. To enhance detection accuracy, loads were categorized as resistive or non-resistive, and specific algorithms were applied accordingly. A notch filter was employed to analyze specific frequency ranges in the time domain. To validate the algorithm, detection times were measured using arc current data for each type of load.

MOSFET 패키징을 위한 Cu 클립 및 Al 와이어 본딩의 수치 해석 연구 Numerical Analysis of Cu Clip and Al Wire Bonding for MOSFET Packaging


최나연(Na-Yeon Choi) ; 장성욱(Sung-Uk Zhang)

The demand for efficient power devices and systems is growing, and this is driving the development of highly efficient, miniaturized power devices and devices. The development of high-efficiency power devices requires better packaging technologies. Cu Clip Bonding is gaining increasing interest as a packaging method for high-performance MOSFETs, replacing traditional Al Wire Bonding due to its low resistance and inductance, high power density, and improved thermal performance. It is important to understand the thermal behavior of Cu Clips. In this study, the thermal characteristics of both Al Wire and Cu Clip bonding methods in TO-220 and TO-247 packages are compared using the finite element method.

원통형 차폐 모델에 의한 극저주파 자기장 차폐 효과 해석 Analysis of Extremely-Low Frequency Magnetic Field Shielding Effect Using a Cylindrical Shielding Model


이명복(Myung Bok Lee) ; 주성후(Sung Hoo Ju) ; 송기현(Ki Hyun Song)

To shield magnetic fields in the extremely low frequency(60Hz) band generated from transmission lines and power equipment, the magnetic field shielding effect was analyzed using Faraday 3D. The analysis model was in the form of a cylindrical shielding material surrounding a wire carrying a single-phase current. The shielding material had a single-layer structure of a high-permeability magnetic layer or a highly conductive metal layer, or a multilayer structure consisting of a magnetic layer/conductive metal layer. The analysis was performed by changing physical properties such as relative magnetic permeability, electrical conductivity and the layer thickness. In the case of single-layer shielding, it was difficult to obtain high enough shielding rate with thickness less than 1mm. In the case of double-layer shielding, however, high shielding rate of 85.3% was achieved when the magnetic permeability of the primary layer was 100 and the conductivity of the secondary layer was 1.0×105 (S/m) at 0.2mm thickness of each layer. In multilayer structures consisting of three or more layers, the shielding effect was saturated.

구매후기 작성 AI 지원을 통한 고객경험 증진에 관한 연구 Research on Enhancing Customer Experience through AI-Supported Review Generation


박수현(Su-Hyun Park) ; 이예은(Ye-Eun Lee) ; 이한진(Han-Jin Lee)

As online & mobile grocery shopping grow globally amid the COVID-19 pandemic, consumer reviews are having a significant impact on purchasing behavior. As the AI and Bigdata technologies advance, the development of purchase reviews has expanded significantly, necessitating research from a multidisciplinary and convergent perspective. Accordingly, in this study, we proposed and demonstrated four user convenience functions applying the latest technology to multi-dimensionally analyze the purchasing experience of digital consumers. To this end, based on the reviews written by existing customers, we provide the ChatGPT API powered purchase review suggestion functions along with visual representation of keywords (Word Cloud). Also, detailed review recommendations by topic based on CombinedTM Algorithm) topic modeling, search-based review collections are delivered. Analyzing the survey results in depth, while customers' awareness and importance evaluation of purchase review service support functions were high, trust showed differences depending on age group. Through the results, we were able to confirm the importance and positive impact of improving customer experience through AI support when writing purchase reviews. These results are expected to provide practical and policy implications for expanding and improving the ecosystem surrounding digital mediated reviews.

DC 모터 위치 제어시스템을 위한 내부모델 원리 기반 제어기와 외란 관측기 기반 제어기 비교 A Comparison of IMP-based and DOB-based Controllers for a DC Motor Position Control System


손영익(Young Ik Son) ; 임승철(Seungchul Lim)

Robust controller design against time-varying disturbance is one of the most important issues in control system design and analysis. Internal Model Principle-based controller design techniques achieve the robust control performance as the controller includes a dynamic model of reference and disturbance. Disturbance Observer-based controllers designed based on extended system models, including disturbance dynamic characteristics, rely primarily on disturbance estimation to provide the same robustness. However, there are not many studies on the similarity of these two control techniques. This paper extends a previous result on the similarity of the two controllers for speed control system to more general position control systems. An extended analytical study is performed to obtain the equivalent property between the two classes of controllers for general higher-order systems. Based on the derived condition, DOB-based controllers can be designed to show the same performance as IMP-based controllers. Position control simulations are included to validate the equivalent performance between the controllers.

증분 용량 분석법과 딥러닝을 이용한 리튬 이온 배터리의 SOH 추정 방안 연구 Study on Lithium-ion Battery SOH Estimation Based on Incremental Capacity Analysis and Deep Learning


박민식(Min-Sik Park) ; 김정수(Jeong-Su Kim) ; 김병우(Byeong-Woo Kim)

Lithium-ion batteries are being utilized as energy sources for electric vehicles due to their advantages such as high energy density, long life, and high efficiency. In order to ensure the safe condition of lithium-ion batteries under various driving conditions of electric vehicles, it is necessary to analyze the degradation status and causes of lithium-ion batteries and accurately estimate their state of health (SOH). Therefore, this paper proposes a method for estimating the SOH of lithium-ion batteries using incremental capacity analysis and deep learning. Incremental capacity analysis is a technique that analyzes the electrochemical state inside a lithium-ion battery and can identify the degradation state of the battery. Through this method, parameters related to degradation were extracted, and their usefulness as characteristic parameters for SOH estimation was verified by correlation analysis. The characteristic parameters validated through correlation analysis were used as inputs to deep learning algorithms for SOH estimation to compare the accuracy of SOH estimation by different estimation algorithms.

저비용 6축 IMU센서를 이용한 양치구역 추정을 위한 기계학습 모델 개발 A Machine Learning Model for Toothbrush Position Tracking using a Low-cost 6-axis IMU Sensor


권민욱(Minwook Kwon) ; 임대연(DaeYeon Lim) ; 김도윤(Doyoon Kim) ; 류승재(Seungjae Ryu) ; 조은아(Eunah Jo) ; 김영욱(Young Wook Kim) ; 김진현(Jin Hyun Kim)

The recent epidemic of respiratory diseases has underscored the importance of personal oral health care. Oral diseases, primarily caused by viral infections, can be reduced by regularly eliminating oral microorganisms. Effective tooth brushing is fundamental to oral health, but changing established brushing habits can be challenging. Adherence to recommended brushing techniques is challenging across all age groups, including children, older people, and adults. This study uses data from a low-cost, 6-axis IMU sensor and a machine learning-based classification algorithm for 13 brushing positions. We evaluate eight machine learning models using the sensor’s acceleration and angular velocity data and assess their performance using various metrics. Our results show that these models can classify brush positions with approximately 89% accuracy. This method enables monitoring of brushing areas and analysis of brushing patterns to improve brushing quality and adherence to recommended techniques. Consequently, by improving brushing quality, it is possible to maintain primary personal oral care and prevent various diseases.

전기요 사고사례를 통한 안전기준 개선 방안에 대한 연구 Research on ways to Improve Safety Standards through Electric Blanket Accident Cases


홍성준(Seong-Jun Hong) ; 태동현(Dong-Hyun Tae) ; 김정환(Jeong?Hwan Kim) ; 방선배(Sun-Bae Bang)

The rapid spread of heating mats combined with Korea's ondol-style housing culture has led to more than 200 fire incidents annually. In particular, incidents related to overheating caused by non-metallic sheathed wire (NM cable) used in electric blankets are reported to the Consumer Protection Information Center and compiled by the National Fire Agency's Fire Statistics Center each year. NM cable consists of a heating element wound in a spiral pattern on synthetic fibers (PE), insulated with nylon, and further wound with detection wires in a spiral pattern. The impedance of the nylon thermistor, which changes with temperature, is used to control the electrical signal flowing from the heating element to the detection wires based on temperature. This paper verifies the uniformity of impedance changes in NM cable based on temperature for different electric blanket products. Specifically, it confirms the temperature increase in electric blankets through heating experiments and its correlation with the impedance changes in NM cable. The experimental results showed variations in impedance changes even for the same product, and in cases where the rate of impedance change is not consistent, it was confirmed that overheating of over 100°C can occur due to excessive heating.

인체 감전 및 지락 위험성 저감을 위한 직류 누전차단기 사양 선정에 관한 연구 Research on Specification of DC Ground Fault Interrupters to Reduce the Risk of Human Electric Shock and Ground Fault


임승택(Seung-Taek Lim) ; 이기연(Ki-Yeon Lee) ; 채동주(Dong-Ju Chae) ; 오찬혁(Chan-Hyeok Oh)

With the increasing interest in green energy, there is a constant demand for renewable energy and DC power systems. DC systems are known to be an efficient system due to energy loss reduction and efficient control, and safer than AC systems in terms of electric shock. Therefore, research and demonstration projects are being carried out. However, those related to electrical safety and installation regulations are insufficient. As a result, the commercialization of related appliances and equipment is delayed. One of them, the lack of installation regulations for DC-RCDs, whose installation is almost mandatory under the Korea Electric Code(KEC), hinders the expansion of DC buildings and reduces the electrical safety of those who directly use electricity. In order to improve this situation, this paper, based on International Electronical Commission(IEC), analysed the risk of human electric shock due to the occurrence of DC leakage and ground fault, and proposed the minimum specification of DC leakage current protect devices for low-voltage electrical consumers according to the circumstances and to the technology that can be applied to existing equipment.

머신러닝 기반 전차선 분할 및 높이 측정 방법 개발 Development of Machine Learning-based Segmentation and Height Measurement Method for the Contact Wires


정대현(Daehyeon Jeong) ; 이기원(Kiwon Lee) ; 박철민(Chulmin Park) ; 김동규(Dongkue Kim)

Contact wires of catenary system are critical components of electric railways, providing electrical power to trains through contact with the pantograph. Improper installation of the wires can lead to abnormal wear on the contact strips of the pantograph, reducing performance and shortening its lifespan. Therefore, measurements of construction errors in the wires are frequently performed, currently conducted manually by on-site personnel. To reduce measurement time, labor requirements, and fatigue, this study proposes a method for automating the measurement of contact wire height by segmenting them from 3D point cloud data. Initially, wires are detected using Random Sample Consensus (RANSAC), and then Gaussian Mixture Models (GMMs) and Gaussian Mixture Regressors (GMRs) are used to refine the segmentation. A comparison of the measured height at 76 points using a laser rangefinder and the height from the algorithm yielded an average error of -1.2 mm, with a standard deviation of 3.4 mm.

MMC 기반 VSC-HVDC의 사고 위치에 따른 저항형 초전도 한류기와 암 인덕터의 Analysis of Current Limit and Interruption Characteristics of R-SFCL and Arm Inductor According to Fault Location of MMC based HVDC


문병수(Byung-Soo Moon) ; 최효상(Hyo-Sang Choi)

High voltage direct current (HVDC) has gained prominence as a method for connecting renewable energy sources and interconnecting electric power systems between countries. Recently, the modular multilevel converter (MMC) has been developed and is undergoing construction worldwide. MMC-HVDC represents a new conversion technology that can address the issues of switching loss and harmonics. During a fault in the MMC-HVDC system, the fault current rises rapidly due to the discharging of the SM capacitor, making it difficult to interrupt with continuous AC side current feed. This phenomenon leads to the destruction of semiconductor devices. To resolve this issue, superconducting fault current limiters with fast response characteristics have been applied to the MMC. The SM capacitor discharge continues until all IGBTs are blocked. Generally, the IGBT block delay is about 3 ms. However, the response time of the Resistive SFCL (R-SFCL) is faster than 3 ms. In this study, the characteristics of R-SFCL and the arm inductor under multiple fault locations in a long cable of the MMC system are confirmed using PSCAD. The R-SFCL is modeled based on actual experimental data. As a result, as the inductor’s capacity increases, the peak current decreases, and the farther the fault location is, the faster the DC current reaches zero-point. Conversely, in the case of R-SFCL, as the resistance increases, the peak current decreases, and the closer the fault location is, the faster the DC current reaches zero-point.

제어코일 전류변화 패턴을 활용한 가스밀폐형 직류 접촉기 동작상태 판정 기법 Operating Status Decision Of Gas Sealed DC Contactor by Coil Current Change Pattern


차승우(Seung-Woo Cha) ; 김종빈(Jong-Bin Kim) ; 이민구(Min-Goo Lee) ; 박광재(Kwang-Jae Park) ; 김재언(Jae-Eon Kim)

As electric vehicles and LVDC distribution systems expand, demands for DC contactor are increasing. DC Contactor is a device that acts as a switch in the system, and the most important performance is the stability of operation. To check if the on-off operation is normal or not, the pickup voltage applied to the control coil is measured and judged until now. However, it is difficult to confirm the complete operating on-off state of DC contactor by it. In order to solve this problem, this paper presents a method to determine whether DC contactor is completely on or off through some changes in the control coil current. A theoretical basis is presented to explain the change in electromotive force, and it is verified that the method is able to accurately determine the on-off state through experiments.

사물인터넷과 연계 안전사고 예방시스템 연구 A Study on the Safety Accident Prevention System in conjunction with the Internet of Things


박양권(Yang-Kwon Park)

Recently, in an Internet of Things environment, devices (objects) with built-in sensors or communication functions are connected to the Internet by utilizing a physical network that allows objects equipped with IoT sensors and communication chips to automatically exchange real-time data without human intervention. It can collect surrounding information, exchange this information with other devices, and even make appropriate decisions. It can be said to be a huge state system of wired and wireless networking objects based on attached sensors and chips. Here, we provide a practical and systematic approach to overcome the limitations of preventing safety accidents such as safety education, safety equipment, and on-site safety inspections by securing a strong safety net against repeated occurrences of habitual electric shock accidents and to overcome the continuous occurrence of accidents despite multifaceted efforts to achieve zero accidents. Through transformation, the need to develop a system that combines accident prevention and IoT technology is emerging. With the implementation of the Severe Accident Punishment Act, key requirements such as setting safety and health goals and management policies, a dedicated safety and health organization, risk assessment, budget, safety and health management manager, deployment of professional personnel, listening to workers' opinions, and safety and emergency measures when entrusting contracts are stipulated. there is. It has been confirmed that it is useful in electrical safety prevention activities for the purpose of ensuring the safety and health of all people working in a business or workplace, as well as creating a safe environment by preventing safety accidents.

아이형 현수클램프의 L-PBF 적층 제조를 위한 열 이력 시뮬레이션 및 서포트 기반 최적화 Thermal History Simulation and Support-Based Optimization in L-PBF Manufacturing of Eye-Shaped Catenary Clamps


윤석철(Seok-Chul Yun) ; 박영(Young Park) ; 신재호(Jaeho Shin)

This study performed thermal history simulation and strategy optimization for additive manufacturing of eye-shaped catenary clamps used in high-speed railway overhead lines. Instead of the conventional casting material CuAl10Fe2, SUS 316L material suitable for additive manufacturing and having good toughness was used. The thermal analysis simulation software for additive manufacturing was utilized to optimize the additive manufacturing strategy for the parts where heat diffusion was not sufficient. The optimized additive manufacturing strategy was verified by simulation while adding supports, and the accuracy of the simulation was confirmed by comparing the simulation results with the actual experimental results. The results of this study can provide useful guidelines for additive manufacturing of eye-shaped catenary clamps and can be applied to other parts with complex shapes.

PBF 적층 제조 공정 중 매크로 해석을 통한 불균일 단면의 support별 열 누적 최소화에 관한 연구 A Study on Minimizing Heat Accumulation by Supports of Non-uniform Cross Sections Using Macro Heat Transfer Analysis in PBF Additive Manufacturing


윤석철(Seok-Chul Yun) ; 신재호(Jaeho Shin) ; 김재웅(Jae-Woong Kim) ; 최균석(Kyunsuk Choi)

In this study, a numerical analysis model was developed for temperature distribution history analysis. To verify the numerical model, the temperature accumulation results analyzed through simulation were compared with the temperature accumulation results for each layer measured with an IR camera. Through temperature distribution history analysis using the commercial program vAMfire/Macro ⓡ, the maximum height at which the maximum temperature is reached in each process according to the change in cross-sectional area was predicted. In addition, the temperature distribution history for each support was analyzed considering general support, wall support, and modified wall support to minimize heat dissipation and heat accumulation. The difference in heat dissipation effect depending on the type of support was quantitatively analyzed. By applying optimal support, we were able to solve the stacking problem caused by heat accumulation. Through heat transfer analysis, it was confirmed that quantitative analysis was possible to solve problems such as lamination failure and thermal deformation.

대규모 태양광발전이 연계된 배전계통에서의 LVRT를 고려한 고장해석 연구 A Study on Fault Analysis during Low Voltage Ride Through Operation in Large-scale PV System


강현우(Hyun-Woo Kang) ; 박성준(Seong-Jun Park) ; 조동일(Dong-Il Cho) ; 이승민(Seung-Min Lee) ; 문원식(Won-Sik Moon)

In 2022, KEPCO implemented grid support functions for PV systems to prevent blackouts from voltage and frequency fluctuations during system failures. This includes Low Voltage Ride Through (LVRT), which poses concerns about fault currents affecting grid protection systems like Recloser and OCGR. Prior studies on PV integration fault analysis were limited to MW capacities and didn't cover malfunctions in grid support functions like LVRT. This paper analyzes grid flow with increasing PV capacity, using a PSCAD model of a smart inverter for simulating the LVRT function and conducting fault analysis. It focuses on the single line-to-ground fault (1LG), the most common in distribution systems, calculating fault current values, and recommends integration methods with existing protection systems by evaluating different capacity-based cases.

L-PBF 제조공정에서 17-4PH 스테인리스 강의 Down-skin 영역 미세조직 및 기계적 물성에 관한 연구 A Study on Microstructure and Mechanical Properties in the Down-skin area of 17-4PH Stainless Steel using Laser Powder Bed Fusion Addictive Manufacturing


김영경(Yeong-gyeong Kim) ; 어두림(Du-Rim Eo) ; 이승호(Seung-ho Lee) ; 최균석(Kyun-suk Choi)

17-4 Precipitation Hardening Stainless Steel(17-4PH SS) is a material with excellent corrosion resistance and high strength and has recently been widely used to make parts of complex shapes through the Laser Powder Bed Fusion(L-PBF) process. The high strength is expressed by fine and uniform precipitation of Cu deposits in the martensite matrix tissue. However, in the L-PBF process, laser is selectively irradiated on metal powder to melt and solidify the local area repeatedly, and even if 17-4 PH SS powder of the same composition is used and the process conditions are kept uniform, the cooling rate and thermal history of each area are different depending on the shape of the sculpture. As a result, it appears a different microstructure(martensite fraction, etc.) depending on the area of the final stack, resulting in uneven mechanical properties. In particular, in the case of L-PBF products with complex geometries, heat dissipation is not smooth in the Down-skin area, so stacking failures frequently occur , or even if they are successful, unexpected problems with weak mechanical property occur frequently. These results could be suggested for observing microstructure and mechanical properties on the Down-skin area of 17-4PH Stainless Steel processed by Laser-Powder Bed Fusion.

자율주행 이동로봇의 속도 제어를 위한 유도차선과 컴퓨터 비전 기반 주행 알고리즘 Guidance Lanes and Driving Algorithms Based on Computer Vision for Speed Control of Autonomous Mobile Robot


김정주(Jung-Ju Kim) ; 최재훈(Jae-Hoon Choi) ; 김동진(Dong-Jin Kim) ; 최상열(Sang-Yule Choi)

Conventional mobile robots control driving speed using various sensors data. However, in this paper, we present the speed control method for mobile robot using a single vision sensor and a guidance lane. The proposed guidance lane contains the speed control information of the mobile robot. In addition, installation is simple and economical without the need for embedding separate guidance devices. The speed control accuracy of the mobile robot was obtained through experiments. The experimental results demonstrated that the mobile robot system proposed in this paper is capable of accurate speed control with an accuracy of 97.30 %. Therefore, it is expected to make an important contribution to expanding the scope of use of mobile robots to various application fields.

상전류 차분(SDI) 기반 배전계통 HIF 검출기법 개선에 관한 연구 A Study on Improving SDI-based HIF Detection Method in Distribution Systems


이준호(Jun-ho Lee) ; 임춘성(Choon-Seong Leem)

The HIF(High Impedence Fault) that occurs in the distribution system is not just a simple system failure, but it can cause very dangerous situations such as fire (forest fire) or electric shock to the public. In order to detect this, an adaptive tuning method for phase current difference (SDI [Sum of Difference Current]) has been disclosed, but it has not yet been verified in the domestic distribution system. In this paper, a detection algorithm is implemented and supplemented, and the result of confirming the validity of the SDI detection method using the fault current waveform of the HIF obtained from the domestic distribution system is presented. It is expected that this study will prevent non-detection and false detection of HIF.

재생에너지 확대를 대비한 전력 - 가스 연계 계통 시뮬레이션 기초 연구 A Simulation of Integrated Power ? Gas System for Renewable Energy Expansion


고대원(Daewon Go) ; 이동호(Dongho Lee)

This paper presents basic research on simulation of integrated power-gas system to solve stability problems due to the expansion of renewable energy. This paper describes the stability of the power system to check the impact of renewable energy on the system. In addition, the power and gas systems are modeled and formulated according to their characteristics, and the analysis of the gas system is carried out by applying the analysis method of the power system. These methods are validated using commercial simulation tools. We then use Python optimization to simulate an integrated system that minimizes the overall overload rate of the power system. The simulation is divided into two cases, one with high load and one with high generation, and shows the difference in the overload rate of each mother ship with and without integration. The simulation uses IEEE 6 bus and a 14-node gas system.

스퍼터 공정을 이용하여 얇은 글라스 및 두꺼운 플라스틱 기판에 증착된 ITO 투명 전도막의 광학 및 전기적인 특성 분석 Optical and Electrical Properties of ITO Transparent Conductive Film Deposited on thin Glass and Thick Plastic Substrates using Sputtering Process


김경보(Kyoung-Bo Kim) ; 정금관(Geumkwan Jung) ; 김신우(Sinwoo Kim) ; 김무진(Moojin Kim)

In this study, ITO (Indium Tin Oxide) commonly used as a transparent conductive film was deposited on thin glass and thick plastic substrates using DC sputtering equipment, and the optical and electrical characteristics were analyzed. For the experiments, ITO film thicknesses of 900 Å, 1100 Å, and 3200 Å were formed on two different substrates. First, the electrical surface resistance showed a sharp increase from 29 Ω/□ to 16.5 MΩ/□ as the film thickness increased. Next, an analysis of the reaction between light and the film was investigated. The absorption rate shows an opposite trend to transmittance. The bandgap of the films could be determined using absorption. It was found that as the thickness increased, the bandgap decreased. For the application of ITO with a thickness of 1000 Å as a transparent electrode in AMOLED, the researchers examined transmittance and surface resistance based on oxygen concentration.

배전계통 분산에너지 수용성 산정에 대한 PMU 유효성 분석 Analysis of PMU Feasibility for Estimating DERs Hosting Capacity in Distribution System


김담(Dam Kim) ; 김용순(Yong Soon Kim) ; 신재현(Jae Hyeon Shin) ; 김진혁(Jin Hyeok Kim)

This paper addresses the estimation of hosting capacity in light of the rising distributed energy resources (DERs), focusing on the application of the high-precision phasor measurement unit (PMU) in distribution systems. The urgent imperatives of rapid climate change and carbon neutrality goals have accelerated the proliferation of DERs. Consequently, the expansion of DERs is outpacing the enhancement and new installation of distribution systems, highlighting the need to precisely assess their hosting capacity. This study examines the applicability of PMU in accurately estimating hosting capacity, applying an optimization-based method. Utilizing this methodology in the IEEE 33-bus distribution system, the results demonstrate that the implementation of PMU in place of conventional remote terminal units (RTU) enhances the integration capacity of DERs. Further investigations delve into how measurement uncertainty of PMU impacts the acceptability of DERs, offering valuable insights into the limitations and potential of PMU deployment in modern distribution systems.