http://doi.org/10.5207/JIEIE.2025.39.4.245

Chin-Woo Yi ; Hyun-Bae Choi

This paper derived a theoretical equation of the road surface luminance for the interior zone of a road tunnel. The derived values, based on five assumptions were compared with experimental standard values. The theoretical formulas were derived by comparing the threshold of the photoreceptor cells sending signals to the brain with the assumptions, using Weber-Fechner’s law and absolute physical quantities. The results indicated that the case using absolute physical quantities closely followed the road surface luminance standard values, suggesting that the threshold of the photoreceptor cells did not follow Weber-Fechner’s law.

http://doi.org/10.5207/JIEIE.2025.39.4.249

Jeong-Yeon Han ; An-Seop Choi

In modern society, as time spent indoors increases, the importance of artificial lighting to support comfort, productivity, and well-being has become more evident. It is recognized that existing fixed lighting systems face challenges in providing the flexibility needed to adjust lighting in real time based on user behavior, spatial features, or changing environmental conditions. Kinetic lighting control systems are seen as a solution to meet the diverse needs of users engaged in various activities that require specific lighting conditions to maintain visual comfort, improve efficiency, and support biological rhythms. For instance, a lighting system can be designed to support both patient comfort and staff efficiency in the ward. The bed angle responsive system adjusted lighting according to the patient’s position, providing focused lighting for treatments or reading and dim, comfortable lighting for sleep. Additionally, robotic arm systems provided precise lighting for specific needs, kinetically adjusting as they moved throughout the room. The mobile stand light automatically followed a occupant, delivering shadow-free lighting to ensure optimal conditions for doing something. Simulations in Unreal Engine Program allowed detailed testing and refinement of these systems before their physical implementation, demonstrating that kinetic lighting systems can improve productivity, energy efficiency, and user well-being.

http://doi.org/10.5207/JIEIE.2025.39.4.260

Byeong-Chul Yu

The engines of large trucks and buses, which are the most widely used means of transportation in recent years, are improving their performance characteristics as they become larger. Depending on the vehicle’s lifespan and model age, more than 750,000 vehicles are scrapped every year, and the residual value of discarded vehicle engines is more than 50%. By developing an engine generator by recycling known remaining waste common rail (common rail direct injection engine) diesel engines, the performance is excellent while the manufacturing cost can be significantly reduced. In addition, after development, it is an engine that can be commercialized from industrial to home use. One of the main technologies used in recycling engines is inverter control technology. In the case of rotary inverters, there was no product that could be miniaturized while considering the durability, reliability, and economic feasibility of the system and enabling high-efficiency operation. It was an inverter study that was not optimized for the system. In this study, an inverter with characteristics suitable for waste engine generators was studied and applied to industrial sites.

http://doi.org/10.5207/JIEIE.2025.39.4.266

Hee-Sung Lim ; Kyo-Beom Lee

This paper proposes a method for estimating the SOH (State of Health) of an LFP battery pack for electric vehicles using AI algorithms. Among the AI algorithms, CNN receives the battery's time series data as an image and extracts features to estimate the battery's state. LSTM(Long Short-Term Memory) can estimate electrochemical parameters in real-time based on time series data and learns the output time series data of CNN and the battery's charge/discharge cycle data to predict the remaining life of the battery. As a result of the estimation, we confirmed that when estimating SOH using the LSTM model, higher SOH estimation accuracy can be obtained compared to linear regression analysis.

http://doi.org/10.5207/JIEIE.2025.39.4.273

Jung-Han Kim ; Rae-Young Kim

The Harmonics have emerged as one of the major causes of power quality degradation in modern electrical systems, and their impact is becoming increasingly severe due to the growing presence of nonlinear loads. Harmonics distort voltage and current waveforms, leading to problems such as equipment overheating, malfunction, and reduced lifespan, ultimately compromising the stability and reliability of power systems. Therefore, the proper design of power feeders that account for harmonic-generating loads is considered a critical task. This study investigates power feeder design methods capable of effectively addressing harmonics, based on the National Electrical Code (NEC) and the Institute of Electrical and Electronics Engineers (IEEE) standards. The analysis focuses on IEEE Std 519 for harmonic limits and examines relevant NEC provisions related to conductor selection, overheating prevention, and neutral conductor overcurrent. Additionally, through case studies of power quality issues caused by harmonics, this paper outlines key design considerations and presents technical countermeasures such as harmonic filters, mitigating transformers, and specialized cables. This review aims to provide practical design guidance for engineers to ensure the stability and efficiency of electrical installations in harmonic-rich environments.

http://doi.org/10.5207/JIEIE.2025.39.4.283

Yeunggurl Yoon ; Sunghoon Jung ; Yongju Son ; Sungyun Choi

This paper introduces an approach to the modeling and simulation of instability scenarios, aiming to analyze and prevent sub-synchronous oscillations. It examines the root causes of instability observed in real-world cases and incorporates the instabilities of inverter-based resources into simulation models. The study verifies the 2007 Minnesota, 2009 Texas, and 2015 Xinjiang SSO cases. Based on MATLAB/Simulink, the simulation model refer grid structures and instability conditions of real events. The results confirm that this simulation modeling can similarly replicate the dynamic characteristics of real-world instabilities, supporting further analysis and mitigation of SSO.

http://doi.org/10.5207/JIEIE.2025.39.4.294

Yang-Jin Shin ; Ju Lee

This paper proposes a power conversion system for dental zirconia sintering equipment and verifies its performance using an actual sintering furnace load. Conventional sintering systems often employ a phase-controlled alternating current to alternating current (AC-AC) converter, which suffers from distorted current waveforms, low power factor, and limited temperature control accuracy. To address these issues, a two-stage topology is adopted, consisting of an alternating current to direct current (AC-DC) power factor correction (PFC) circuit and a DC?DC buck chopper. The front-end AC?DC stage ensures stable DC rectification with high input power quality, while the rear DC?DC stage enables precise current regulation to the heating element based on the target temperature profile. Simulation and experimental results confirm stable control of power quality, heating current, and chamber temperature, and validate accurate temperature tracking under various sintering schedules.

http://doi.org/10.5207/JIEIE.2025.39.4.301

Hyung-Gyu Kim

This study proposes a sensor-fusion-based real-time monitoring system designed to detect early abnormal signs inside distribution panel and automatically record video when arc is detected. Unlike conventional systems that rely on single sensors or manual inspections, the proposed system integrates temperature, humidity, vibration, and illuminance sensors to continuously monitor internal conditions. When thresholds are exceeded, it triggers alerts and saves related video data. Experimental results confirm its effectiveness in fast and accurate detection, enhancing monitoring reliability. This system offers foundational technology for improving predictive maintenance and accident response in electrical facilities.

http://doi.org/10.5207/JIEIE.2025.39.4.307

Sun Jae Kim ; Tae Hun Kim ; Seung-Woo Woo ; Min Hyeok Kang

This study investigates electric shock accidents involving non-standard electric welders manufactured by modifying microwave oven transformers, a trend that has been increasingly observed in DIY(do it yourself) high-voltage equipment usage. Two fatal electric shock incidents were analyzed, both of which involved welders lacking basic electrical safety designs such as insulation and protective circuits. These structural deficiencies were identified as the primary causes of the accidents. Experimental measurements revealed that the open-circuit voltage at the secondary side of the modified welders exceeded 2,000V, far surpassing the safety limit of 95 V specified in KS C 9602:2007. Simulations of human body resistance, using enamel resistors ranging from 1kΩ to 5kΩ, demonstrated that the current varied with resistance. Notably, at 1kΩ-a representative value for human body resistance under moist or conductive conditions?an alarming 1.2 A of current was recorded. The victims' hands showed severe burns and carbonization, indicative of sustained high current flow through body tissues. This study proposes institutional enhancements in safety regulations and distribution control measures. The findings provide foundational data for the establishment of effective safety management systems to prevent severe electrical accidents associated with unauthorized high-voltage equipment.

http://doi.org/10.5207/JIEIE.2025.39.4.313

Yun-Sang Yu ; Chang-Hyun Kwon ; Woo-Cheol Jeong ; Chan-Hun Yu ; Hyoung-Suk Kim ; Sung-Roc Jang

This paper presents the development of an isolated converter module for a high-voltage pulsed power modulator, where multiple cells composed of capacitors and switches are connected in series to generate high voltage. The module is designed to withstand insulation voltages up to 10 kV for application in high-voltage systems. An LCC resonant converter topology is adopted to achieve soft switching, thereby reducing switching losses at high switching frequencies. Moreover, to minimize conduction losses, the resonant current is shaped into a trapezoidal waveform to reduce the RMS value of the current. Additionally, a voltage sensing method employing a tertiary winding is proposed to enable output voltage control regardless of variations in the output potential. The proposed voltage sensing method is validated experimentally, and the performance of the developed converter module is verified through both simulations and experiments.