Mobile QR Code QR CODE : The Transactions of the Korean Institute of Electrical Engineers

전기차 충전 장소를 고려한 그리드 일부하곡선 분석 Analysis of Grid Daily Load Curve by taking into consideration PEVs Charging Station

https://doi.org/10.5370/KIEE.2019.68.11.1283

최상봉(Sang-Bong Choi) ; 이재조(Jae-jo Lee)

This paper presents a methodology to calculate the daily load curve per city by taking into consideration a charging station for electric vehicles, which easily determines the effect of the load owing to the charging of electric vehicles in Seoul. In particular, we calculate the charging power of uncontrolled plug-in electric vehicles (PEVs) in terms of the daily running characteristics of vehicle travelling between homes and workplace, with respect to PEV charging stations in the city, according to the market share of PEVs. Furthermore, we calculate the load curve for the simultaneous charging strategy of controlled PEVs in terms of the vehicles’ daily running characteristics between homes and workplaces and a time-of-use (TOU) price plan of the Seoul Metropolitan Government under uncontrolled and controlled charging types. Thus, we are able to analysis the effect of the total existing electricity load and the abovementioned daily load on the grid. Because we can precisely determine the effect of the hourly charging load of PEVs on a power grid in Seoul using these study results, we can establish a PEV charging load management plan to prevent power grid reinforcement and expansion while satisfying the overload constraint of the power grid in Seoul using an appropriate TOU price plan.

낙뢰 보호 구역과 접지방식을 고려한 태양광 발전설비의 낙뢰 서지 영향 Influence of Lightning Surge on Photovoltaics Considering LPZ Protection Level and IEC-60364 Grounding System

https://doi.org/10.5370/KIEE.2019.68.11.1288

조재영(Jae-Young Cho) ; 김규호(Kyu-Ho Kim) ; 이재균(Jea-Kyun Lee) ; 우정욱(Jung-Wook Woo)

This paper analyzes the change of lightning overvoltage due to the grounding system and LPZ consideration. In IEC-60364, three different grounding methods are introduced to protect the facilities from transient overvoltage in different situation. IEC-61312 defines the LPZ(lightning protection zone) so that different methods of lightning protection can be taken at different protection level. by adjusting surge arresters as specified in IEC-62305. This paper simulates how much lightning overvoltage is occurred in photovoltaics and how its condition varies under the change of grounding system method and the type of surge protection device used.

스위칭 특성을 고려한 전류형 시스템의 댐핑회로 설계 적정성 검토 Evaluation on Design of Thyristor Snubber Circuit considering Switching Characteristics in LCC HVDC System

https://doi.org/10.5370/KIEE.2019.68.11.1292

이철희(Chur Hee Lee) ; 김승완(Seung Wan Kim)

This paper deals with the evaluation on the design of thyristor snubber circuit for LCC(Line Commutated Converter) HVDC system. Snubber circuit consists of capacitance and resistance to protect thyristor in HVDC system. Based on turn off model, mathematical expressions are derived by considering the maximum device stress, maximum reverse dv/dt, and reverse energy loss of a power device. The total turn-off loss in the device with the associated snubber circuit is considered as stray inductance. In the case of determining ratio between resistance and capacitance, it is important to reflect their relation and the purpose of protecting thyristor. Considering these analytical solutions to 500kV HVDC system in Korea, we can calculate the range of maximum and minimum rate of the thyristor snubber circuit. This study can be applied to review the design of thyristor snubber circuit of HVDC projects.

태양광발전모형 예측력 제고를 위한 지역별 기상요소 적용방안 연구 Application of Regional Weather Factors on the PV Generation Modeling for Improving Forecast Accuracy

https://doi.org/10.5370/KIEE.2019.68.11.1304

김완수(Wan-Soo Kim) ; 조하현(Ha-Hyun Jo)

To make robust dispatch plan, the accuracy of forecasting model for PV is one of the most important factor. At the present, Korea Power Exchange has used the information of meteorological measuring points at the central place of administration in each provinces when they predict the amount of PV generation. But unlike national electricity demand forecasting, these weather information could make bigger PV forecasting error than we expected. In this study we reconsider appropriateness of existing meteorological information and try to find more suitable meteorological measuring points. And also we tried to apply the forecasting combination methodology on the Korean regional PV forecasting to improve the forecasting accuracy.

무선전력전송을 위한 단일전력단 레벨 하이브리드 교류 직류 컨버터 A Single Stage 3-Level Hybrid AC-DC Converter for Wireless Power Transfer

https://doi.org/10.5370/KIEE.2019.68.11.1312

김민지(Min-Ji Kim) ; 김은수(Eun-Soo Kim)

In this paper, we propose a single-phase single-stage hybrid AC/DC converter that can regulate the output voltage and improve the input power factor through phase shift modulation (D) at a constant switching frequency for wireless power transfer. In the proposed single stage AC/DC converter, formula to calculate the input power factor (PF) and the total harmonic distortion (THDi), and the voltage gain characteristics of CLLC resonant circuit for WPT are analyzed and presented. Also, the performance of the proposed single stage AC/DC converter was verified on a 1 kW prototype operating with an ac line voltage (220Vrms) and an output voltage (Vo) that varies between 250VDC and 350VDC.

능동 소나용 고효율 고출력 송신기의 설계 Design of High-efficiency High-power Transmitter for Active Sonar

https://doi.org/10.5370/KIEE.2019.68.11.1321

송승민(Seung-Min Song) ; 김인동(In-Dong Kim) ; 이병화(Byung-Hwa Lee) ; 이정민(Jeong-Min Lee)

To implement long-distance transmission and reception of signals in the water, low frequency acoustic waves should be used for low attenuation of underwater signals. However, the underwater acoustic transducers used in generating the acoustic wave, have widely variable impedance characteristics as well as large capacitive components depending on the driving frequency bands. The high-power transmitter should be designed properly to drive such acoustic transducers safely, reliably and efficiently. This paper proposes the efficient high-power transmitter for the acoustic transducers. The proposed high-power transmitter improved about the efficiency and THD(Total Harmonic Distortion).

계통 연계형 인버터를 위한 필터 설계 Design of an LCL-Filter for Grid-Connected Hybrid ANPC Inverters

https://doi.org/10.5370/KIEE.2019.68.11.1330

김예지(Ye-Ji Kim) ; 김상훈(Sang-Hun Kim) ; 배규철(Kyu-Chul Bae) ; 이교범(Kyo-Beum Lee)

This paper proposes an LCL-filter design procedure for three-level hybrid active neutral point clamped (ANPC) inverters in grid-connected systems. Although more active switches are used, the hybrid ANPC inverter help to balance the loss distribution. The hybrid ANPC inverter consist of silicon insulated gate bipolar transistors (Si IGBTs) and silicon carbide metal-oxide-semiconductor field effect transistors (SiC MOSFETs). The hybrid ANPC inverter can be operated at high switching frequency compared to neutral-point-clamped (NPC) inverters. Therefore, the hybrid ANPC inverter has low switching losses due to the physical characteristic of the SiC MOSFETs. The inverter-side inductance is determined by the ripple factor of the hybrid ANPC inverter. To calculate the ripple factor, the output current ripple is required. In the grid-connected inverter, the output current ripple is related to the grid voltage, output phase voltage, and inductance. Thus, the inductance is calculated by using the equation of ripple factor. The filter capacitance is designed by the reactive power absorption ratio and the grid-side inductance is determined by the ripple attenuation factor. The effectiveness of the proposed LCL-filter design method for the hybrid ANPC inverters was verified by the simulation results and experimental results.

감쇠진동파에 의한 의 파괴특성 분석 The Destruction Effect of LNA(Low Noise Amplifier) by Damped Sinusoidal

https://doi.org/10.5370/KIEE.2019.68.11.1338

방정주(Jeong-Ju Bang) ; 허창수(Chang-Su Huh) ; 장태헌(Tae-Heon Jang)

This study has examined destruction effect on LNA(Low Noise Amplifier) by damped sine wave. DFR(Destruction Failure Rate) was measured to investigate the diagnostic of LNA test. Three kinds of damped sine wave were injected to input port of LNA module: 1 MHz, 10 MHz, and 100 MHz. The destruction level of LNA was assessed by damped sine wave voltage, and its DFR were observed. The destruction of LNA module has showed the degradation of amplification or loss of amplification function. As the frequency of damped sine wave increased, the destruction threshold voltage increased and destruction threshold energy decreased. Based on these results, the destruction effect of LNA can be used to protect the RF communication equipment from high power electromagnetics.

변압기 부분방전 진단 성능 향상을 위한 센서 최적설계방안 연구 The Study of UHF Sensor Design Optimized for Transformer Partial Discharge Measurement

https://doi.org/10.5370/KIEE.2019.68.11.1343

이종건(Jong-Geon Lee) ; 오승열(Seung-Ryle Oh) ; 한기선(Ki-Sun Han) ; 강지원(Ji-Won Kang) ; 주형준(Hyung-Jun Ju)

This paper deals with the study on partial discharge(PD) characteristics of transformer and method of UHF sensor design for transformer PD measurement. The experiment was fabricated according to IEC-60270 and IEC-62478. The analysis of PD characteristic and spectrum of various transformer defect was performed. From the result, it was deduced that PD signal of each defect has unique frequency band, and it was also found that the improvement of sensitivity of UHF sensor which is optimized for transformer could be achieved by tuning reflection loss of sensor by forming resonance point at specific frequency.

완전결합 유한요소법을 이용한 정극성과 부극성 기체방전 메커니즘의 수치해석적 분석 Numerical Analysis for Positive and Negative Discharge Mechanisms in Air by Using Fully Coupled Finite Element Method

https://doi.org/10.5370/KIEE.2019.68.11.1349

김수헌(Su-Hun Kim) ; 이세희(Se-Hee Lee)

Numerical analysis was carried out using a fully coupled finite element method to analyze mechanisms for positive and negative discharges in air. To analyze these discharge mechanisms, we have employed the charge continuity equations for carriers such as the electron, and positive and negative ions, and the Poisson’s equation for the electric field including the ionization, attachment, and recombination effects. The space charge density was numerically estimated according to the time, and the streamer initiation and propagation processes were analyzed for the positive and negative discharges. Further, to analyze the discharge mechanism, the electron, negative and positive ions densities were estimated with time. Finally, To verify our numerical setup, the numerical results have been compared with those from the previous experimental results reported in the literature.

계면 상태에 따른 연면방전 특성에 관한 연구 A Study on Characteristics of Surface Discharge with Interface Condition

https://doi.org/10.5370/KIEE.2019.68.11.1355

최진욱(Jin-Wook Choe) ; 이웅엽(Woong-Yup Lee) ; 남석현(Seok-Hyun Nam) ; 김진규(Jin-Gyu Kim)

As the competition in the electrical power cable market becomes more intense, not only the quality and the price, but also the ease assembly are becoming important. The failure in the joint and termination were caused by surface discharge along the interface of cable insulation and rubber sleeve for electric field grading. The factors affecting the surface discharge are contamination, interfacial pressure, surface roughness and lubricant. In this paper, the difference of surface roughness was investigated based on the grain size of sandpaper to simplify the cable preparation process. In addition, the influence of the factors was evaluated by the surface discharge test according to the surface roughness, the interface pressure, and the type of the lubricant.

표면개질된 나노실리카의 충진함량에 따른 의 및 전기적 Epoxy Nano Composites HVDC HVAC 절연파괴 특성 HVDC and HVAC Electrical Breakdown Characteristics of Epoxy Nano Composites According to the Filling Content of Surface-Modified Nanosilica

https://doi.org/10.5370/KIEE.2019.68.11.1360

승오탁(O-Tak Seung) ; 박재준(Jae-Jun Park)

In this study, the surface of nano silica was modified to improve the insulation characteristics of high voltage based heavy electric equipment. The surface-modified nanosilica was homogeneously dispersed by filling the epoxy resin with different contents (0,1,3,5,7,9phr) and Epoxy / Nano Silica Composites were prepared. The glass transition temperature was determined for the homogeneous dispersion of surface-modified nanoparticles, and for evaluation of interfacial and thermal properties. Short-term HVDC positive polarity breakdown and HVAC breakdown characteristics were evaluated as electrical insulation performance improvement. Also, for the long-term reliability evaluation, the AC electrical tree characteristic was evaluated under inequality by frequency acceleration degradation method. The glass transition temperature increased with the increase of the content of nano-silica surface-modified on the epoxy resin, and the dielectric breakdown strength increased with the filling content of HVDC insulation breakdown and decreased with HVAC. Moreover, the insulation life decreased with the increase of the filling content in the long time electric tree experiment.

다중 유전체에서의 공간전하 분포 측정 및 신호 보정에 대한 연구 Study on the Measurement and Signal Correction of Space Charge Distribution in Multi-dielectrics

https://doi.org/10.5370/KIEE.2019.68.11.1368

김형규(Hyung-Gyu Kim) ; 정현철(Hyun-Cheol Jung) ; 박준도(June-Do Park) ; 황보승(Seung-Hwangbo)

In recent year, as the demand for large-scale power transmission and DC cables has increased due to the connection between inter-country grid and offshore wind power generation around the world, high voltage direct current (HVDC) cables have been extensively studied. However, as for long-distance transmission, such as for power grid and offshore wind power generators, a DC high voltage is continuously applied to the internal insulator of the cable, there is a high probability of insulation breakdown due to space charge. The cable connection box consists of several dielectrics and due to the presence of interfaces between adjacent dielectrics, distortion of the electric field occurs, and various problem such as electrical insulation occur. In this study, the Pulsed-Electro-Acoustic (PEA) method is used to measure multi-dielectric space charge distribution signals and a new signal processing algorithm is developed. we use the deconvolution method whereby the original signal is restored using the measured signal and the system response function, this method is an algorithm widely used to obtain the reliability of the signal. We developed a program using signal processing algorithm and LabVIEW S/W, and successfully corrected the measurement signal.

이종 필러 추가에 따른 에폭시 마이크로 복합체의 절연성능 연구 Study on Insulation Performance of Epoxy Micro Composites with Co-filled Fillers

https://doi.org/10.5370/KIEE.2019.68.11.1375

전영택(Youngtaek Jeon) ; 지용진(Youngjin Ji) ; 변영훈(Younghoon Byun) ; 김명진(Myungchin Kim)

In this paper, essential properties that affect electrical insulation performance of epoxy micro composites were studied. In particular, the effect of adding co-filled micro sized fillers to epoxy composites were explored. The fillers considered in this study include 40 [um] BN, 22 [um] SiO2, 5 [um] Al2O3 and 5 [um] TiO2. For each composite, dielectric constant, dielectric loss, tracking resistance and breakdown field intensity were tested. When BN and SiO2 particles were added, the dielectric constant and the dielectric loss increased. By co-filling TiO2 and Al2O3 particles to the BN/Epoxy composite, a change in dielectric properties were observed. Different performance among epoxy composites were observed depending on characteristics of the co-filled filler. Experiment results demonstrated the effectiveness of epoxy composites with co-filled micro particles. Results of this research could contribute to optimized design of epoxy composites for improved insulation performance.

배전용 가스절연개폐기 부분방전 진단의 적정 주파수 분석 Analysis of Proper Frequency Range for Partial Discharge Diagnosis in Distribution Gas Insulated Switchgear

https://doi.org/10.5370/KIEE.2019.68.11.1382

고현상(Hyeonsang Ko) ; 윤성호(Seongho Yoon) ; 김정태(Jeongtae Kim)

In order to improve the accuracy of partial discharge diagnosis by distinguishing internal partial discharge and external noises in distribution grade SF6 gas-insulated switchgear, partial discharges were measured for the on-site operated switchgears. Floating discharges due to water immersion defect in bushing, SF6 gas leakage defect, poor conductor-contact defect etc. were considered as internal discharges, and discharge by peeling semi-conductor paint in bushing was considered as external discharge. As a result, the main frequency bands of internal and external discharges were identified, and it was proposed that frequency bands of the partial discharge sensor would be designed in the range from 250MHz to 350MHz for detecting internal partial discharges.

실리콘 고무 마이크로 복합체의 내트래킹성에 대한 연구 Research on AC Tracking Resistance of Silicone Rubber/BN Microcomposites

https://doi.org/10.5370/KIEE.2019.68.11.1389

변영훈(Younghun Byeon) ; 전영택(Youngtaek Jeon) ; 김명진(Myungchin Kim)

Surcace tracking resistance is an essential characteristic that determines the performance of insulation materials for outdoor applications. In this research, the tracking resistance of boron nitride (BN) filled silicone rubber (SiR) composites were evaluated based on tracking time comparison from inclined plane test (IPT). SiR/BN composites with BN loadings of 0, 3, 5, 10 and 20 wt% were manufactured and it was shown that improvement in tracking resistance is achieved by increasing the loadings of BN particles. Considering that tracking resistance is affected by various materials properties such as heat conducitivity, thermal stability and hydrophobicity, the effect of different BN loadings to the material properties of SiR/BN composite were studied by thermal simulation, thermo-gravimetric analysis (TGA) and surface contacnt angle (SCA) measurement. From analysis for such detailed material properties, it was shown that the additon of micro-sized BN particles contribute to increased level of thermal conductivity, thermal stability and SCA. Instead of direct measurements, in addition to evaluation of tracking resistance, a computational approach to predict thermal conductivity of composites was considered to study the effect of different BN loadings to SiR/BN composites. The effectivenss of the applied prediction approach was studied by comparing prediction results with conventional models.

T-S 퍼지 모델 기반 쿼드로터의 H ∞ 보장 비용 제어기 설계 Design of H ∞ Guaranteed Cost Controller of a Quadrotor Based on a T-S Fuzzy Model

https://doi.org/10.5370/KIEE.2019.68.11.1396

이경학(Gyeong Hak Lee) ; 김도완(Do Wan Kim)

This paper proposes a Takagi-Sugeno (T-S) fuzzy-model-based design for the ∞ guaranteed cost control of a class of nonlinear quadrotor. The proposed guaranteed cost controller is designed for the position and attitude control of quadrotor with disturbances. Through the sector nonlinearity, the quadrotor dynamics is represented by the T-S fuzzy model. Its sufficient conditions for asymptotic stabilization are derived in the format of a linear matrix inequality. Simulation results demonstrate the effectiveness of the proposed methodology.

전반부 불일치 조건에서의 불확실한 시스템의 상태 추정을 위한 샘플데이터 퍼지 관측기 설계 Sampled-data Fuzzy Observer Design for State Estimation of Uncertain Systems Under Imperfect Premise Matching

https://doi.org/10.5370/KIEE.2019.68.11.1403

김한솔(Han Sol Kim) ; 주영훈(Young Hoon Joo)

In this paper, we propose a sampled-data fuzzy observer design technique for estimating the state variables of a nonlinear system with model uncertainty. It is assumed that the IF-THEN rules of the fuzzy system contains immeasurable premise variables, which complicates the observer design. In this paper, the observer is assumed not to share the same premise part with that of the system in order to deal with the immeasurable premise condition. After then, the error between the observer and the system including model uncertainty is represented by the Takagi-Sugeno (T-S) fuzzy model. In order to minimize the impact of imperfect premise matching, model uncertainty, and disturbances on the state estimation, an ∞ performance criterion is defined. Based on the fuzzy Lyapunov function, we derive a sufficient condition in the form of linear matrix inequality to ensure that the error dynamics is asymptotically stable and satisfy the ∞ condition. Finally, a simulation example verifies the superiority of the proposed method.

LSTM 알고리즘을 활용한 전기 수요고객의 온라인 질문에 대한 토픽분류 Classifying Customer’s Written Questions by Topics Using Deep Learning (LSTM)

https://doi.org/10.5370/KIEE.2019.68.11.1411

나상태(Sang-Tae Na) ; 양광동(Gwang-Dong Yang) ; 신재섭(Jae-Seop Shin)

In response to questions or complaints posted by customers on the company's homepage, the response time is an important measure of customer satisfaction. However, the time it takes for a customer to receive an answer includes a time for the article to be selected by the person in charge of the reply, which limits the shortening. In this study, we developed a model in which a machine, not a person, reads the article, classifies the topic, and delivers it to each person in charge of the article. The article posted on the KEPCO homepage used in this study is a short sentence consisting of an average of 49 words. Due to the scarcity of multi-frequency words, it was found that there is a limit in securing a certain level of topic modeling accuracy in unsupervised machine learning like LDA. To overcome this, we labeled topics and let the machine conduct supervised learning. Although there are limitations in improving accuracy because there are articles containing more than two topics in one article, the classification accuracy is secured up to 84% by using LSTM and Baysian Optimization. The result of this study suggests that topic classification is possible for short-term customer questions in specific fields such as the electric power industry. In addition, it is expected that a model will be developed that can provide optimal reference answers for newly received questions when the topic-labeled questions and answers are fully accumulated.

BHUI: 이진 논리 연산을 활용한 하이 유틸리티 마이닝 기법에 대한 연구 BHUI: A New Bitwise Operation-based High Utility Itemset Mining

https://doi.org/10.5370/KIEE.2019.68.11.1417

황정희(Jeong-Hee Hwang) ; 지정희(Jeonghee Chi) ; 박소영(Soyoung Park)

Pattern mining finding frequent patterns are widely used to search useful information from large scale data. General pattern mining, however, have the problem of not applying the characteristics of the individual items because all items have the same importance. High utility itemset mining that solves this problem retrieves meaningful information by applying a relative weight to each item. In this paper, we propose a new high utility itemset mining algorithm based on bitwise operations. The bitwise operation predetermines the likelihood of joining two itemsets to reduce the join operation. Since the join operation is the most time consuming operation in the high utility itemset mining, the proposed algorithm significantly reduces the mining time. We analyzed the performance of the proposed algorithm with execution time and the number of generated utility itemsets and compared the performance with HUI-Miner. Our experimental results show that the proposed algorithm outperforms HUI-Miner.

은닉 마코프 모델을 이용한 심전도 검출 최적화에 관한 연구 A Study on the Optimization of ECG QRS Detection Using the Hidden Markov Model

https://doi.org/10.5370/KIEE.2019.68.11.1425

김상민(Sang-Min Kim) ; 이혁재(Hyeok-Jae Lee) ; 민경진(Kyoung-Jin Min) ; 김경섭(Kyeong-Seop Kim) ; 곽휘권(Hwy-Kuen Kwak) ; 고윤수(Yun-Soo Ko) ; 채제욱(Je-Wook Chae) ; 이정은(Jung-Eun Lee) ; 이정환(Jeong-Whan Lee)

The heart is the body's circulatory organ that supplies blood to the body. An electrocardiogram is the best means of measuring and diagnosing abnormal conduction of the heart muscle. Therefore, to diagnose patients suspected of heart disease, a Holter monitoring system measuring electrocardiography for 24 hours is used by doctors to examine and diagnose patients. However, diagnosing innumerable Holter data entails considerable effort by doctors directly. If QRS can be detected by an automated diagnostic system, many Holter data could be classified without diagnosing it by clinicians directly. In this paper, we tried to detect the QRS of electrocardiogram using the Hidden Markov Model. For objective verification, the onsets and offsets of QRS, which classified by the specialist, in the QT-database, were used as the reference labels. The Mexican Hat mother function was used for the wavelet transform. To study how to optimize the learning of hidden Markov models, the experiment was conducted by changing the batch size of the training data sets and the scale of the wavelet mother function. During the verification process, the mean and standard deviation of the difference between QRS onset and offset obtained from the test data sets through the hidden Markov model and the reference label classified by a specialist were used. As a result, the batch size was found to have the best performance using all 84 training data sets, and the scale of the mother function was found to have the best performance using scale j = 2, 3, 4. When the mean and standard deviation of QRS complexes detected from the hidden Markov model was -8.2822ms, ±5.821476ms(p=0.99818) onsets, respectively and -2.9588ms, ±6.5662ms(p=0.99838) offsets, respectively with 84 batch sizes and all three scale mother functions were trained, the results of onset, offset standard deviation were improved average about 22.1%, 30.9% respectively when compared with other algorithms using QT-Database

가중 누적 정규화 매개변수를 이용한 표면근전도 신호의 근피로도 정도 구별 Muscle Fatigue Level Discrimination of Surface EMG Signals by Using Weighted-cumulated-normalized Parameters

https://doi.org/10.5370/KIEE.2019.68.11.1434

이진(Jin Lee)

This paper presents a trial to discriminate muscle fatigue level based on surface electromyogram signals during sustained isometric %MVC (maximum voluntary contraction). Surface EMG signals(a total of 198 signals) were recorded in biceps brachii muscle with isometric 20% and 80% MVC contractions from eleven subjects. Six new weighted-cumulated-normalized parameters, WC (weightedcumulated-normalized) MNF (mean frequency), WC MDF(median frequency), WC SMR(spectral moment ratio), WC TUF(turn frequency), WC SPF(spike frequency) and WC ZCF(zero-crossing frequency) were investigated in terms of both robustness and sensitivity for muscle fatigue estimation of the SEMG signals. From the investigation, the best parameter was selected and used to discriminate muscle fatigue level quantitatively. Results of this study suggest that WCMDF is most reliable parameter for muscle fatigue estimation and the trail for discriminating muscle fatigue level with the WCMDF parameter shows good performance for all the 11 subjects.

각 로 교차하는 두 송전선의 특정점 를 통한 최단거리 연결 Shortest Connection of Transmission Lines with Intersection Angle  via Specific Point (p, q)

https://doi.org/10.5370/KIEE.2019.68.11.1440

김주철(Ju-Chul Kim) ; 이상중(Sang-Joong Lee)

For a transmission line in electric power grids, the shorter the length of the line is, the smaller the ohmic loss inside the line is. Shorter line length contributes to lower construction cost in general. Shorter highway length enables faster transportation of goods. Shorter road length contributes to lower logistical cost in general. This paper presents a derivation to determine the length of a straight line that minimally connects two axes with intersection angle θ via a specific point (p,q) using optimization technique. The authors propose a formula represented by a cube equation w.r.t. the coordinate of the specific point (p,q) and intersection angle θ, through which the minimal length and x-y’ intercepts of the connection line are obtained. Case studies are discussed to check if the solutions derived by the proposed formula are optimal. This paper may be used as an optimization lecture note for students majoring in electrical engineering.

인공지능을 활용한 전력계통 운영관련 자동 법령 질의응답 플랫폼 구축 연구 A Study on the Construction of an Automatic Legal Question Answering Platform Related to Power System Operation Using Artificial Intelligence

https://doi.org/10.5370/KIEE.2019.68.11.1450

정상웅(Sang-Woong Jung) ; 김래현(Lae-Hyun Kim)

Electricity related laws are directly related to the property and life of the people, and they contain the preventive and practical work contents, reporting methods and procedures. In order to solve the problems such as interpretation of the law, it is best to answer directly by a person with expert knowledge, but real-time answers are difficult due to limited manpower and working hours. Therefore, in this study, we developed an AI question and answer platform that utilizes big data that allows the general public to easily ask and answer laws related questions. We want to build a system.

대규모 태양광발전소의 개별접지 및 통합접지에 따른 안전전압 (보폭전압 및 접촉전압) 비교 분석 An Analysis and Comparison of Safety Voltage (Step Voltage and Touch Voltage) According to Isolation and Common Grounding System of Large-Scale Photovoltaic Power Plant

https://doi.org/10.5370/KIEE.2019.68.11.1458

이창욱(Chang-Uk Lee) ; 김재철(Jae-Chul Kim)

Large-scale photovoltaic power plant facilities have been steadily growing not only in Korea but also in the world. As the importance of designing a large-scale photovoltaic power plant grounding system to prevent human electric shock accidents and equipments damage caused by ground faults are emphasized. In order to prevent human electric shock accidents and equipments damage, the grounding system should be designed to limit the safety voltages(step voltage and touch voltage) when a ground faults. In this paper, the safety voltage of critical facilities for the large-scale photovoltaic power plants are compared when applying fault currents to grounding systems(isolation grounding/common grounding) applied to large-scale photovoltaic power plants with simulation utilizing CDEGS.

용량결합형 전극에서 가이드링에 의한 전기장 제어 Electric Field Control by Guide Ring in Capacitively Coupled Plasma Electrode

https://doi.org/10.5370/KIEE.2019.68.11.1465

구교욱(Kyo-Woog Koo) ; 이연(Yeon-Lee) ; 구경완(Kyung-Wan Koo)

In the case of display PECVD, VHF is introduced as the driving frequency. In addition, since the electrode shape has a large area rectangular structure, nonuniformity caused by the standing wave effect and skin effect occurs. In this case, even small changes in the process variables affect the nonuniformity. Against this we propose the electric field control method using guide ring as a part of reduction effect and fine tuning. Using the guide ring, the electrical influence and the optimization method were confirmed by the response surface Methodology and Taguchi experiment. It is considered that fine tuning is possible by utilizing the electrical properties of each factor.

DC ESS 지락에 의한 시스템의 화재에 대한 연구 DC Ground Fault Induced Fire Accident in Lithium Ion Battery based ESS

https://doi.org/10.5370/KIEE.2019.68.11.1470

김훈(Hoon Kim) ; 김승호(Seung Ho Kim) ; 송형준(Hyung-Jun Song)

Energy Storage Systems (ESS) based on lithium ion battery are rapidly increasing their capacity because they can efficiently store electricity in a small area with high energy density. However, 23 fire accidents have been reported for last 21months. To date, the origin of fire has not been clearly elucidated. In this work, we investigated the origin of a fire accident through experimental field analysis and its corresponding simulation. Empirical and theoretical study reveals that the ground fault in battery string would induce high current from gird to battery modules with voltage imbalance, which is enough high to ignite fire. Therefore, it is required to protect ESS system form ground fault in battery modules.

교류 전동차 주회로 차단기 동작특성 연구 A Study on the Operation Characteristics of Main Circuit Breaker for AC EMU

https://doi.org/10.5370/KIEE.2019.68.11.1477

김상현(Sang-Hyun Kim) ; 김철수(Chul-Soo Kim) ; 김재문(Jae-Moon Kim)

This paper presents an analysis of the operating characteristics of MCB in the power system of EMU powered by AC 25kV. The MCB is installed on the roof of the EMU vehicle and it performs on and off operations in poor environments conditions depending on the external environment, such as vibration and temperature changes due to operation. In the Shinbundang-Line driverless EMU vehicle system, as MCB’s operation failures occurred at outdoor temperature range of 1 ~ -11 . It is analyzed the operate ? ℃ ℃ characteristic and the hypothesis theory of operation failure was established. It is verified experimentally and an applicable system is proposed that can operate smoothly under service environment condition. Finally, the results of the verification were applied to the train and the results of the proposed system were verified through long-term and follow-up observation.

타선흡상현상을 고려한 교류철도 급전계통 고장점 표정기법 Fault Location Estimation Technique for AC Railway Power Supply System Considering of the Other Line’s AT Boosting Current Characteristics

https://doi.org/10.5370/KIEE.2019.68.11.1482

정호성(Hosung Jung) ; 김주욱(Joo-Uk Kim) ; 김형철(Hyungchul Kim) ; 민명환(Myung-Hwan Min) ; 안태풍(Tae-Pung An)

This paper presents an improved fault location estimation algorithm to reduce the fault location estimation error ratio in AT boosting current ratio technique. The domestic AC traction system uses the AT feeding system as a standard, and most of the lines are composed of double tracks(up and down lines). It was confirmed that the fault location estimation error is increased due to the change of the AT boosting current of the faulted line due to the other line’s AT boosting current characteristics. Therefore, in this paper, an improved fault location estimation algorithm is proposed by using all AT boosting currents considering of the other line’s boosting current characteristics. In order to evaluate the proposed algorithm performance, the AC railway power supply system is modeled and various fault simulations were performed using the power analysis program. As a result, when comparing the error of the existing technique and the improved technique, the improved algorithm shows an average error of 0.16%, and even the maximum error is 0.88%, which is satisfied within 2% of the domestic standard.

교류전기철도 부하 불평형 개선을 위한 병렬형 능동형 밸런서 적용에 관한 연구 Study on the Parallel Operation of Active Balancer for Unbalanced Load in AC Electric Railway System

https://doi.org/10.5370/KIEE.2019.68.11.1489

김현우(Hyun-Woo Kim) ; 고유란(Yu-Ran Go) ; 민명환(Myung-Hwan Min) ; 안태풍(Tae-Pung An) ; 이태훈(Tae-Hoon Lee)

This paper analyzes an active balancer with parallel structure which can solve the unbalance problem of Scott transformer secondary side load. First, the structure and function of the proposed active balancer system are explained and the inverter hardware design and control algorithm applied to the active balancer are presented. In addition, the interleaving technique applied to the parallel balancer is described. In order to verify the effects of active and reactive power compensation and the interleaving technique, 8 MVA active balancer is designed and confirmed through PSIM simulation.