https://doi.org/10.5370/KIEE.2025.74.5.761

강민규(Mingyu Kang) ; 민동욱(Donguk Min) ; 이보성(Bosung Lee) ; 이연수(Younsoo Lee)

As electric vehicles are recognized for their potential to mitigate greenhouse gas emissions, their adoption has expanded beyond passenger cars to include commercial vehicles such as buses and trucks. Among these, electric buses are notable for their contribution to improving air quality in densely populated urban areas. However, the widespread deployment of electric buses and their associated charging infrastructure has introduced challenges in optimizing power grid stability and managing limited charging resources. Vehicle-to-Grid (V2G) technology, enabling bidirectional energy transfer between vehicles and the grid, has emerged as a promising solution. In this paper, we address a charging and discharging scheduling problem for an electric bus depot equipped with V2G technology. We propose a mixed integer linear programming model which optimizes charging and discharging schedules to achieve two objectives: maximizing net discharging during peak demand hours and minimizing overall operation costs. A hierarchical approach is employed to deal with the two objective functions. To enhance computational efficiency for large-scale instances, a heuristic algorithm based on the optimization model is also proposed. Computational experiments were conducted to demonstrate the advantages of the proposed optimization model and algorithm. The results indicate the potential of V2G technology to not only stabilize the power grid but also provide economic benefits to depot operators.

https://doi.org/10.5370/KIEE.2025.74.5.775

진호원(Ho-Won Jin) ; 최진영(Jin-Young Choi) ; 오상현(Sang-Hyun Oh) ; 임지훈(Ji-Hoon Im) ; 이재원(Jae-Won Lee) ; 조윤성(Yoon-Sung Cho)

The increasing penetration of inverter-based resources(IBRs) has significantly increased the complexity of modern power system, challenging conventional RMS-based analysis tools. As a result, electromagnetic transient(EMT) simulations have become essential for accurately capturing the dynamic characteristics of power systems with high IBR penetration. However, large-scale EMT simulations are computationally demanding, limiting their practical implementation in extensive grid studies. This study proposes an equivalencing technique that transforms RMS-based PSS/E data into an equivalenced model, enabling scalable EMT-based simulations in RTDS and PSCAD/EMTDC environments. The results demonstrate that this approach effectively preserves critical dynamic characteristics while significantly reducing computational complexity, facilitating large-scale transient analysis in high-IBR power systems.

https://doi.org/10.5370/KIEE.2025.74.5.784

권오승(Oh-Seung Kwon) ; 송진솔(Jin-Sol Song) ; 강성만(Sung-Man Kang) ; 김욱원(Wook-Won Kim) ; 김철환(Chul-Hwan Kim)

Due to the proportion of renewable energy increase, DC systems are in demand and the study on AC/DC Hybrid system is ongoing. The current AC distribution system is characterized by a passive, unidirectional flow of power, which limits power control and causes power loss in AC/DC conversion for DC demands. The AC/DC Hybrid distribution system improves system operational efficiency by integrating DC systems into existing AC system, expanding the capacity for renewable energy integration, and reducing conversion losses from AC to DC. However, depending on the line configuration, AC/DC cables may be positioned adjacently, potentially causing electro-magnetic interference (EMI) between them. This paper proposes the best grounding methods of underground cable which is appropriate to the AC/DC Hybrid distribution system. The validation of the grounding methods of underground cable was performed by Electro-Magnetic Transients Program (EMTP) ATP-Draw.

https://doi.org/10.5370/KIEE.2025.74.5.793

이상현(Sang-Hyeon Lee) ; 전웅재(Woong-Jae Jeon) ; 김수열(Soo-Yeol Kim) ; 최윤혁(Yun-Hyuk Choi)

This paper explores the development and implementation of an Energy Storage System (ESS) as a Non-Transmission Alternative (NTA) to address line overload and stability challenges in the Jeju power grid. The primary goal is to enhance grid reliability and efficiency without necessitating extensive expansion of transmission infrastructure, leveraging a 50MW ESS installed at the Geumak substation. The ESS NTA operating system is designed with three distinct operational modes: Mode 1 focuses on mitigating line overload, Mode 2 aims to control line utilization, and Mode 3 is based on renewable energy index-driven control. Each mode incorporates specific algorithms and control strategies, including calculations, control flow diagrams, and program development. Simulation and real-time application results validate the proposed system's effectiveness in reducing line overload, optimizing line utilization, and facilitating the integration of renewable energy.

https://doi.org/10.5370/KIEE.2025.74.5.800

오효빈(Hyo-Bin Oh) ; 윤형석(Hyeong-Seok Yun) ; 윤효정(Hyo-Jeong Yoon) ; 신한솔(Han-Sol Shin) ; 곽규형(Kyu-Hyeong Kwag) ; 김욱(Wook Kim)

As the share of variable energy resources (VERs), increases in power systems, their role and impact on system are expanding. The current method for evaluating the effective capacity of VERs is based on the exceedance level approach. This paper examines whether the existing method is appropriate for high-penetration systems. This paper analyzed the contribution of VERs to system reliability and compared with the existing method. The analysis revealed different criteria were deemed necessary for determining peak contributions for each resource. Additionally, methods to mitigate the variability of peak contributions caused by changes in VER utilization patterns were explored. Based on the scenario analysis results, criteria for determining the peak contributions of VERs were proposed, and the changes in effective capacity resulting from the applying the proposed method were further analyzed.

https://doi.org/10.5370/KIEE.2025.74.5.809

오우림(Woo-Rim Oh) ; 한기웅(Gi-Woong Han) ; 함승준(Seung-Jun Hahm) ; 김영진(Young-Jin Kim)

This study proposes a Python-MATLAB/Simulink based Software-in-the-Loop Simulation (SILS) framework for the pre-validation of microgrid control and operational strategies. The framework integrates a Supervisory Control And Data Acquisition (SCADA) system, enabling real-time monitoring and SILS-based verification of control strategies. To evaluate its effectiveness, the proposed framework was implemented on a IEEE 13-bus system testbed. The accuracy of the SILS framework was validated by comparing the reference inputs from the optimal operational scheduling algorithm with the outputs of the testbed simulation. Furthermore, the results from the islanded microgrid operation scenario demonstrate that the system maintains stability, validating the framework's scalability.

https://doi.org/10.5370/KIEE.2025.74.5.820

최종기(Jong-Kee Choi) ; 이유진(You-Jin Lee) ; 조준호(Jun-Ho Cho) ; 권영훈(Young-Hun Kwon) ; 박지환(Ji-Hwan Park) ; 장영훈(Young-Hun Jang)

In order to improve the reliability of protection systems, performance verification tests of protection relays are essential. KEPCO applies pre-defined test procedures using RTDS for this purpose[13]. For transformer protection relays, performance verification under internal winding fault conditions is necessary. RSCAD/RTDS offers internal fault models not available in similar programs, but it has limitations in representing the actual short-circuit characteristics of three-winding transformers. In contrast, transient analysis programs like PSCAD or EMTP can simulate faults without requiring expensive equipment like RTDS and effectively express the actual short-circuit characteristics of transformers. However, they lack internal fault models. This paper proposes a method to address the limitations of three-winding transformers in RTDS. Additionally, it presents techniques to implement transformer internal faults in ATP-EMTP equivalent to those in RTDS, along with comparative verification cases using the RTDS model.

https://doi.org/10.5370/KIEE.2025.74.5.830

이지선(Ji-Sun Lee) ; 강상희(Sang-Hee Kang)

In power systems, current transformers (CTs) step down high currents, enabling accurate measurement and protection critical for system stability. Protection CTs require high accuracy to avoid relay malfunctions caused by distorted currents. While iron cores enhance flux linkage, their nonlinear hysteresis can introduce measurement errors. This paper proposes a CT simulation model for PSCAD/EMTDC, employing RMS-based excitation curve data provided by manufacturers. The model utilizes the Dommel algorithm for nodal analysis to simulate nonlinear core behavior and core losses without extensive experimental data. Based on a secondary equivalent circuit, it includes magnetizing inductance, hysteresis losses, secondary winding impedance, and burden impedance. Manufacturer‘s excitation curves are incorporated directly using 10 data points, with ‘Loop-width(%)’ quantifying loss currents and simplifying data processing. It’s accuracy was validated via open-circuit tests, capturing saturation characteristics, and verified through comparisons with built-in 'Saturable Reactor' and 'MOV' components, demonstrating the precision of the proposed method in time-domain simulations.

https://doi.org/10.5370/KIEE.2025.74.5.838

변범석(Beom-Seok Byeon) ; 박의종(Eui-Jong Park) ; 김용재(Yong-Jae Kim)

In the EV sector, geared motors with a single gear ratio are commonly utilized. This study aims to replace conventional geared motors with magnetic geared machines(MGM) by integrating magnetic gears. When designing an MGM, simply applying the conventional design methodology of magnetic gears is insufficient, as the influence of the shared rotor, which serves as the coupling component between the magnetic gear and the motor, must be considered. Therefore, this paper proposes a new design methodology for magnetic gears that accounts for the influence of the shared rotor in an MGM. Furthermore, the study presents the design process for an MGM specifically intended for EV applications.

https://doi.org/10.5370/KIEE.2025.74.5.845

김성원(Seong-Won Kim) ; 김상협(Sang-Hyeop Kim) ; 정우성(Woo-Sung Jung) ; 반휘랑(Hwi-Rang Ban) ; 유경태(Kyeong-Tae Yu) ; 박준범(Jun-Beom Park) ; 최연태(Yeon-Tae Choi) ; 김용주(Yong-Joo Kim) ; 신경훈(Kyung-Hun Shin) ; 최장영(Jang-Young Choi)

This paper presents the design and performance comparison of high-speed permanent magnet synchronous motors (PMSMs) based on the rotor structure, analyzed through electromagnetic and mechanical methods. Under the same requirements and constraints, the rotor sizes of high-speed PMSMs were selected using torque per rotor volume (TRV) and split ratio according to the structures of surface-mounted permanent magnet and interior permanent magnet rotors. The electromagnetic and mechanical analyses were performed based on finite element analysis, and the electromagnetic analysis results were extensively compared while considering mechanical stability and manufacturability. Based on the comparison of the comprehensive analysis results according to the rotor structures, it can be widely used in the design of high-speed PMSMs for various applications.

https://doi.org/10.5370/KIEE.2025.74.5.853

김충서(Choung-Seo Kim) ; 이주(Ju Lee) ; 한필완(Pil-Wan Han) ; 지우영(Woo-Young Ji) ; 김성휘(Seong-Hwi Kim) ; 이형우(Hyung-Woo Lee)

In induction motors (IMs), rotor copper losses occur due to the induced current generated by the difference between the rotor speed and the input power frequency, accounting for approximately 25% of total losses. In contrast, the Line Start Synchronous Reluctance Motor (LS-SynRM) experiences a significant reduction in rotor copper losses once it reaches synchronous speed, as no induced current from the fundamental component of the load current is generated, making LS-SynRM more advantageous for efficiency compared to IMs. However, the harmonic components of the load current can still induce rotor currents, which may reduce efficiency. This paper focuses on maximizing the efficiency of a 4-pole, 37kW LS-SynRM through the design of its rotor and stator windings, analyzing the causes of rotor copper losses, and exploring methods to reduce them.

https://doi.org/10.5370/KIEE.2025.74.5.863

김응재(Eungjae Kim) ; 김민수(Minsu Kim) ; 김세환(Sehwan Kim) ; 최길수(Gilsu Choi)

This paper presents an advanced modeling approach for a surface-mounted permanent magnet synchronous motor (SPMSM) drive system that incorporates the nonlinear effects of both the motor and the inverter.The motor model integrates magnetic saturation and spatial harmonics to enhance accuracy, while the inverter model accounts for semiconductor voltage drops and dead time effects.The proposed model was validated through simulations utilizing JMAG-RT and MATLAB-Simulink, as well as experimental verification using a dynamometer. The results demonstrate that output distortions caused by the nonlinearities of the motor and inverter vary significantly depending on the operating points, highlighting the necessity of comprehensively considering these nonlinear effects for accurate analysis of output waveform quality. This study provides a reliable and precise tool for drive performance evaluation during the early design stages.

https://doi.org/10.5370/KIEE.2025.74.5.870

조세빈(Sebin Cho) ; 허진(Jin Hur)

Accurate wind power prediction is essential to ensure grid stability as renewable energy integration increases. However, obtaining precise meteorological data at wind turbine locations is challenging due to technical and economic constraints. This study introduces a prediction model combining spatial interpolation and machine learning techniques using meteorological observations and reanalysis data. By leveraging data from a wind farm in Jeju Island, the model constructs a comprehensive meteorological database using kriging with elevation corrections adapted to seasonal variability, thereby enhancing the spatial coverage of meteorological inputs. Additionally, machine learning based bias correction is applied to forecast data to improve predictive accuracy and enhance practical ? applicability. The proposed approach provides a practical solution for system operators, mitigating grid management risks and supporting the energy transition. Future work will focus on incorporating high-resolution regional forecasts and optimizing the integration of multiple reanalysis datasets to further enhance prediction performance.

https://doi.org/10.5370/KIEE.2025.74.5.878

남상민(Sangmin Nam) ; 이윤재(Yun-Jae Lee) ; 장성욱(Sung-Uk Zhangark)

This study investigates the degradation of electrical insulation performance caused by carbonization in epoxy insulators used in high-voltage transmission systems. A numerical analysis was conducted using finite element analysis-based ANSYS Workbench and Q3D Extractor to evaluate changes in electric field intensity, current density, Joule heat, and charge density as the carbonized length increases. The results show that as carbonization progresses, the electric field intensity, current density, and Joule heat increase significantly, leading to a deterioration of insulation performance. When the carbonization length reaches 90 percent of the insulator, the electric field intensity sharply increases, indicating a critical degradation point. Complete carbonization penetrating the insulator results in insulation failure due to the formation of a conductive path, although dielectric breakdown does not occur under the rated operating voltage of 600V. These findings highlight the importance of early detection and monitoring of carbonization to prevent insulation failure in epoxy insulators.

https://doi.org/10.5370/KIEE.2025.74.5.885

박재준(Jae-Jun Park)

Epoxy resin used in high-voltage power equipment such as molded power transformers and OF power cable joint-boxs is widely used because it has advantages in electrical insulation and stability of mechanical properties. However, when manufacturing power devices, nano and micro void defects occur, and cracks and interfacial defects occur due to thermal expansion coefficient at the interface between the conductor and epoxy microcomposite for a long period of time. In this way, the partial discharge is converted into an electrical tree and the tree is initiated. And it progresses further, ultimately resulting in insulation breakdown. Three types of insulation defects were simulated in epoxy resin: No Void, Void Gap_0.5mm samples. The applied voltage was 13kV/60Hz, and the discharge signal was measured from the voltage application through a microscope and the AE Signal measurement system when Tree-Partial Discharge occurred. To diagnose the deterioration state of Tree-Partial Discharge, the axial tree progression length was measured and evaluated throughout the entire process from the Tree Incubation Period to tree initiation, progression, and destruction. In order to evaluate the characteristics of Tree-Partial Discharge, the waveform of the AE Waveform and the result of FFT (Fast Fourier Transform) execution were converted from time-voltage (amplitude) to frequency-voltage (amplitude) function. In addition, the frequency characteristics of the waveform against the tree-deterioration time were evaluated, and the mechanisms of No Void and void discharge characteristics were analyzed.

https://doi.org/10.5370/KIEE.2025.74.5.894

강규혁(Gyuhyeok Kang) ; 김상엽(Sangyeob Kim) ; 박수민(Sumin Park) ; 백두산(Dusan Beak) ; 윤효원(Hyowon Yoon) ; 석오균(Ogyun Seok)

We propose 1.2 kV Silicon Carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs) integrating internal Schottky barrier diodes (SBDs) on the JFET region. The internal SBDs of 1.2 kV SiC MOSFETs have robust switching performance by reducing Miller Pleteau (Qgd) through the wide depletion region formed in the SBD area and by lowering the forward voltage drops (VF) due to the fast operation of integration SBDs. We analyzed the reduced Qgd and forward voltage drop (VF) of the proposed structure compared to the conventional MOSFET and dummy gate MOSFET by optimizing the width of Schottky metal (WSchottky). Additionally, we evaluate the electrical characteristics including on-resistance (Ron), threshold voltage (Vth), breakdown voltage (BV), VF, turn-on loss (Eon) and turn-off (Eoff) for each structures. Our results demonstrate that the switching loss is significantly reduced by the integration of internal SBDs within 1.2 kV SiC MOSFETs.

https://doi.org/10.5370/KIEE.2025.74.5.899

박수민(Sumin Park) ; 김상엽(Sangyeob Kim) ; 백두산(Dusan Beak) ; 윤효원(Hyowon Yoon) ; 강규혁(Gyuhyeok Kang) ; 하민우(Min-Woo Ha) ; 석오균(Ogyun Seok)

The impact of deep level traps within the bandgap on the breakdown voltage characteristics of 4.5 kV SiC super junction diodes is presented. We demonstrated through TCAD simulations that deep level traps degrade the reverse characteristics of the device and identified a degradation mechanism. Additionally, we analyzed the interactions among trap concentration, energy level, and operating temperature, and the effects of these factors on breakdown voltage. The trap behavior varied depending on the simulation conditions, leading to corresponding changes in the breakdown voltage characteristics. This study highlights that the impact of deep-level traps must be comprehensively considered during the design and fabrication stages of SiC super junction devices.

https://doi.org/10.5370/KIEE.2025.74.5.905

백두산(Dusan Baek) ; 윤효원(Hyowon Yoon) ; 김상엽(Sangyeob Kim) ; 강규혁(Gyuhyeok Kang) ; 박수민(Sumin Park) ; 석오균(Ogyun Seok)

A 1.2 kV SiC H-shaped poly-Si gate MOSFET (HPG MOSFET) structure was proposed to effectively reduce switching loss without compromising static device characteristics. The structure features a locally etched poly-Si gate electrode, and its performance was analyzed by evaluating the specific on-resistance (Ron,sp), gate-to-drain charge (Qgd,sp), and maximum oxide electric field (Eox,max) at the poly-Si gate corner according to the etched area. Under optimized conditions, the proposed HPG MOSFETs achieved a significant reduction in Qgd,sp with only a negligible increase in Ron,sp compared to conventional SiC planar MOSFETs. Additionally, Eox,max at the gate corner remained below 3 MV/cm. These findings demonstrate that the 1.2 kV SiC HPG MOSFET can significantly enhance energy efficiency.

https://doi.org/10.5370/KIEE.2025.74.5.911

석오균(Ogyun Seok) ; 김민기(Minki Kim) ; 하민우(Min-Woo Ha)

SiO2/4H-SiC metal-oxide field-effect transistors (MOSFETs) have been attractive for next-generation power devices. We focused on negative bias temperature instability (NBTI) for the 900 V SiO2/4H-SiC MOSFETs in this work. First, we measured gate leakage current in both positive and negative directions. From these measurements, we found that hole trapping was dominant during NBTI. We measured transfer characteristics before and after applying constant gate voltage stress. We also applied the stress at 150oC for comparisons. We measured the threshold voltage in virgin state, stressed one, and after 24 hours of discharge, respectively. As a result, the threshold voltage was shifted negatively due to NBTI. This negative shift was attributed to a formation of positive charges. The NBTI induced oxide trap charging at room temperature and activated additional traps at 150oC. We also measured the change in gate leakage current, which did not change significantly.

https://doi.org/10.5370/KIEE.2025.74.5.917

최서은(Seo-Eun Choi) ; 서연우(Yeon-Woo Seo) ; 박현용(Hyun-Yong Park) ; 정정교(Jung-Kyo Jung) ; 강혜민(Hye-Min Kang)

Silicon-Carbide Metal-Oxide-Semiconductor Field-Effect Transistors (SiC MOSFETs) are crucial for next-generation power conversion. Conventional SiC MOSFETs primarily utilize a 3-lead package, which is simple in structure and cost-effective. However, the common source inductance of the package increases switching losses. To address this issue, a 4-lead package has been introduced. Nevertheless, research on its switching characteristics is still limited. This study compares the switching characteristics of TO-247-3L and TO-247-4L SiC MOSFETs with identical chip sizes through double pulse tests. Moreover, switching losses under different temperature conditions were analyzed for various chip sizes of TO-247-3L and TO-247-4L SiC MOSFETs. The findings indicate that switching losses of TO-247-4L SiC MOSFETs were lower than TO-247-3L SiC MOSFETs. Additionally, turn-off energy losses increased with temperature, while turn-on energy losses varied depending on chip sizes and package types.

https://doi.org/10.5370/KIEE.2025.74.5.926

남상민(Sangmin Nam) ; 이윤재(Yun-Jae Lee) ; 석오균(Ogyun Seok) ; 장성욱.(Sung-Uk Zhang)

This study investigates the electrical and thermal characteristics of SiC PiN diodes mounted on a ceramic package through both experimental measurements and finite element analysis (FEA). The research focuses on evaluating the impact of packaging process variations on the equivalent material properties of the device. Electrical resistivity and thermal conductivity were extracted from 22 samples and compared to assess process-induced deviations. The results indicate that variations in wire bonding and die bonding significantly influence the device’s electrical resistance and thermal conductivity. In particular, samples with lower electrical resistance exhibited higher thermal conductivity, suggesting that packaging quality plays a crucial role in overall device performance. Furthermore, the equivalent material properties derived from experimental data were applied to the simulation model, demonstrating strong correlation with the measured values. This approach provides a systematic method for quantifying process-induced variability in power semiconductor packaging and offers insights for optimizing package reliability. The findings of this study contribute to the enhancement of power semiconductor packaging by enabling a more accurate and efficient evaluation of material properties, ultimately improving device performance and thermal management strategies.

https://doi.org/10.5370/KIEE.2025.74.5.933

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

Gallium Nitride (GaN)-based High Electron Mobility Transistors (HEMTs) are regarded as key devices for next-generation high-power and high-frequency applications. The performance of these fast-switching devices is significantly influenced by packaging, which affects their electrical, thermal, and mechanical behavior. In this study, a full-factorial Design of Experiments (DOE) approach was employed in combination with Finite Element Analysis (FEA) to evaluate the effects of key packaging parameters, including wire material, wire diameter, and solder joint height. Electro-thermal-structural simulations and electromagnetic analyses were conducted to assess the influence of these variables. Statistical evaluations using Multivariate Analysis of Variance (MANOVA) and Response Surface Modeling (RSM) were also performed. The optimized design, which incorporated thick gold wires (0.05 mm diameter) and a low solder joint height (0.02 mm), effectively minimized thermal stress while enhancing electrical performance, achieving a total desirability score of 0.67. The results of this study are expected to contribute to improved reliability and performance in GaN HEMT packaging.

https://doi.org/10.5370/KIEE.2025.74.5.942

남의석(Eui-Seok Nahm)

Biological processes are characterized by complex interactions between environmental conditions and process variables, and therefore the operational experience of skilled experts plays an essential role in process optimization. However, such expert experience is often conveyed as implicit rules and is often not explicitly systematized, requiring a data-based verification process. In this paper, in order to verify the expert operation rules of biological processes, we modeled a biological process based on an artificial neural network and verified the expert operation rules from this model using the SHARP technique of XAI. Through this, we aim to determine whether the direction of the expert operation rules is appropriate and what additional factors should be considered. The analysis results using the XAI technique through simulation using three years of data from a sewage treatment plant using a biological process in the metropolitan area showed that the expert operation rules of biological processes are basically in the direction and that additional supplementary elements of expert operation rules are needed. These results of this paper are believed to provide a reliable basis for experts when applying ANN models to biological process operations, and can contribute to improving the transparency of AI-based decision-making systems. In addition, it was confirmed that it is possible to further supplement expert operating rules.

https://doi.org/10.5370/KIEE.2025.74.5.950

유희정(Heejeong Yoo) ; 이은수(Eunsu Lee) ; 유훈(Hoon Yoo)

This paper presents a method for an efficient programming language identification technique which consists of selection of target categories and machine learning for unknown category. As software development scales are complicated, the source codes in use are getting huge and diverse. A programming language identification technique is essential to manage source codes effectively. However, existing research lacks a clear rationale for target categories selection criteria and does not address the issue of unknown categories. In this paper, we propose a method for selecting target categories based on frequency of use and importance, and machine learning techniques to handle unknown categories. We present three methods for classifying the unknown categories. Experimental results demonstrate that the proposed methods effectively classify the unknown categories.

https://doi.org/10.5370/KIEE.2025.74.5.957

(Erdana Seitzhan) ; (Alibek Bissembayev) ; (Assel Mukasheva) ; 박해산(Hae San Park) ; 강정원(Jeong Won Kang)

The aim of this article is to study the effects of Low Code Development Platforms (LCDPs) on contemporary software engineering practices, focusing on the acceleration of application development procedures, reduction of development costs, and democratization of application development. Low-code platforms use visual development environments to allow professional developers and “citizen developers” to build applications with very little coding. The benefits and challenges of LCDPs are highlighted in this research through a review of literature, case studies, and survey analysis. LCDPs can significantly enhance efficiency and reduce costs, achieving up to a 50% reduction in development time for smaller projects. However, their effectiveness diminishes in larger projects where extensive customization and integration are required. Survey results indicate that 85% of professionals agree on efficiency improvements, but challenges related to scalability and integration remain a concern. Moreover, both PSO and NLP optimize feature selection and workflow allocation, further reducing execution time by 16.8%. This provides practical implications and demonstrates the potential of LCDPs in their role in software development going forward.

https://doi.org/10.5370/KIEE.2025.74.5.969

나건우(Kunwoo Na) ; 최근하(Keun Ha Choi) ; 김우용(Wooyong Kim)

Lithium iron phosphate (LFP) batteries are increasingly adopted in electric vehicles (xEVs) and battery energy storage systems (BESS) due to their thermal stability, safety, and cost-effectiveness. Despite these advantages, the inherently low electrical conductivity and flat charge-discharge voltage profile of LFP batteries present significant challenges for accurate state estimation. To address these limitations, this study employs a Sigma-Point Kalman Filter (SPKF), which demonstrates superior performance compared to the conventional Extended Kalman Filter (EKF) in handling nonlinear system dynamics. Furthermore, to account for the hysteresis behavior characteristic of LFP cells, quasi-open circuit voltage (qOCV) measurements are utilized. A Dual Sigma-Point Kalman Filter (DSPKF) is proposed to enhance the estimation of both state of charge (SoC) and hysteresis states. The experimental results validate the effectiveness of the proposed method, offering a high-precision state estimation framework that improves the reliability and performance of LFP batteries in xEV and BESS applications.

https://doi.org/10.5370/KIEE.2025.74.5.977

유승철(Seungcheol Yoo) ; 김강민(Kangmin Kim) ; 정준호(JunHo Jeong) ; 소윤섭(Yoonsub So) ; 박영(Young Park) ; 윤용호(YongHo Yoon) ; 최원석(Wonseok Choi)

In this paper describes the distribution panel real-time electrocution safety diagnosis system technology based on the capacitance and relative leakage distribution analysis algorithm, and applies the safety technology to prevent electrocution accidents caused by leakage current such as faulty ground facilities and connection status. A distribution panel capacitance detection module and a facility multi-point leakage detection module were developed. Through this, a technology to prevent electrocution accidents by monitoring the capacitance and leakage current of the distribution facility is secured, and it is expected that by applying a technology to detect abnormal conditions by analyzing the capacitance and leakage current signals inside the distribution panel, the cost required for regular inspection in the power facility system can be reduced and electric accidents can be prevented.

https://doi.org/10.5370/KIEE.2025.74.5.983

이승재(Seung-Jae Lee) ; 신정현(Jeong-Hyun Shin) ; 전무이(Mu-Yi Jeon) ; 문종필(Jong-Fil Moon)

The bifacial PV module is a module that obtains maximum power from sunlight incident on the front and rear sides, and the maximum power varies depending on the ground and installation environment on the rear side. Using these characteristics, we created a reflector that can simulate the ground environment to find the condition that the incident light on the rear side is maximized and to find the economical and time-benefit of the existing IEC standard method. First, the reflectors were installed and evaluated at regular interval for the distance between the reflectors and the modules, and it was found that the maximum power value was saturated over a certain distance, and the same result was obtained for the two modules with different ratings. I think this is one of many ways to replace the IEC standard method based on the current single-sided solar module, and we will further improve the evaluation method through experiments on various ground and installation environmental conditions.

https://doi.org/10.5370/KIEE.2025.74.5.989

위영민(Young-Min Wi)

Jeju Island is faced with considerable challenges in day-ahead load forecasting due to its high share of renewable energy, unique industrial structure, and strong seasonal tourism influence. Particularly on special days such as national holidays and vacation periods, significant fluctuations in load patterns are observed, which complicate accurate forecasting. While existing forecasting models have been developed primarily for mainland power grids, their direct application to Jeju Island has been shown to yield lower accuracy, due to the island’s distinctive demand characteristics.To overcome these limitations, a statistical forecasting model based on similar-day analysis has been developed. In this model, analogous weekdays are selected using key meteorological and calendar variables, and Jeju’s high weather sensitivity along with the impact of behind-the-meter solar generation is incorporated. A case study using real grid data from Jeju Island was conducted. As a result, the proposed model achieved a mean absolute percentage error (MAPE) of 3.24% for hourly demand on the day ahead. This approach is expected to enhance the reliability of power market operations and supply planning, particularly for regions like Jeju Island where conventional forecasting methods are less effective.

https://doi.org/10.5370/KIEE.2025.74.5.996

김유섭(Yoo-Seop Kim) ; 선희정(Hee-Jeong Seon) ; 최영준(Yeong-Jun Choi)

As interest in climate change increases around the world, the awareness in renewable energy as a replacement for fossil fuels is increasing. In Korea, the 'RE3020' announced the target of achieving over 50GW in renewable energy facilities by 2030. As numerous renewable energies have been installed in Jeju Island, the number of curtailment has been increased every year since 2015. As a way to reduce curtailment, sector coupling in the form of Power-to-X (P2X) along with the energy storage system (ESS) is attracting attention. In this paper, curtailment in 2030 is analyzed based on the renewable energy power generation facility target plan specified in the 10th Basic Plan for Electricity Supply and Demand. The forecast for power generation is derived from the utilization rates of solar and wind power, along with the capacity of the power generation facilities. Afterwards, through estimation of sector coupling demand resources in 2030, the curtailment power is analyzed by applying a method of consuming it as a sector coupling resource.