http://doi.org/10.5207/JIEIE.2025.39.3.160

Youngho Son ; Youl-Moon Sung

In this study, we investigate the electrical and optical characteristics of an electrochemical luminescence (ECL) device employing transition metal complex compounds as luminescent materials. The synthesis of the luminescent material involves a two-step process, including heating and recrystallization. Proton Nuclear Magnetic Resonance (1H-NMR) spectroscopy was used to confirm the composition of the synthesized material.. To assess the performance of the luminescent materials, the product was dissolved in 1g of acetonitrile (ACN) along with 4wt% (0.04g) of PVDF-co-HFP. Subsequently, an electrolyte was fabricated and placed between two fluorine-doped tin oxide (FTO) glass substrates, followed by the application of a direct current (DC) voltage ranging from 0V to 4.5V in 0.5V increments. The results of this experiment allowed us to examine the interplay between electrical parameters,thermal properties and the optical properties of the device. In particular, the fabricated electrolyte successfully addressed the limitations of liquid electrolytes while retaining its desirable features, including flexibility.

http://doi.org/10.5207/JIEIE.2025.39.3.167

Jae-Wook Ahn ; Byeong-Seok Yu ; Uh-Chan Ryu

Simulation plays a crucial role in optical design, allowing for the rough predictions of light distribution and irradiance without the need for physical fabrication. Conventional simulation approaches often rely on trial-and-error to identify optimal solutions; however, this can be both time-consuming and costly. To overcome these challenges, obtaining an approximate solution as an initial estimate and refining through simulation can be a more efficient strategy in terms of both time and cost. In this study, a reflector was designed to uniformly distribute light emitted from a UV-C LED with a Lambertian profile onto a target area. This was achieved by calculating three-dimensional spatial vectors. The resulting design served as the initial input for simulations to determine the optimal solution. As a result, the overall simulation time was significantly reduced, and the proposed method enabled the straightforward derivation of initial simulation parameters without requiring complex calculations.

http://doi.org/10.5207/JIEIE.2025.39.3.174

Sang-Wuk Shin ; Seok-Oh Bang ; Jin-Sung Rho ; Jong-Min Lim

Streetlights generally are intended to ensure the safety of drivers and pedestrians by providing a certain level of illumination on roads during nighttime travel. However, keeping streetlights continuously illuminated throughout the night results in significant energy (electricity) consumption. To address this issue, smart streetlights have been developed, which utilize sensors to detect the presence of vehicles and pedestrians or assess traffic volume, thereby providing only the necessary level of brightness and drastically reducing energy consumption. Beyond energy-saving functions, research and development have been conducted in South Korea on traffic safety-oriented smart streetlights. These systems analyze the infrastructure of streetlights along with various sensors and video data to actively reduce traffic accidents. Examines the first-ever deployment of smart streetlights in South Korea, implemented in Gangneung, Gangwon Province, to provide traffic safety services. It details the process of selecting the demonstration site, the 15 scenario-based traffic safety services offered, the hardware system components of the smart streetlight, and conducted with diverse user groups. Through this study, we comprehensively examine the entire demonstration process and its practical implications.

http://doi.org/10.5207/JIEIE.2025.39.3.182

Seok-Won Yoon ; An-Seop Choi

This Analysis aims to analyze the architectural changes and evolution of facade lighting in the main entrances of apartment complexes in Daegu City over different periods and propose future design directions. By categorizing cases in 10-year intervals from the 1990s to the 2020s, the study found that main entrances have evolved from focusing solely on simple access control and security to becoming multifaceted spaces emphasizing symbolism and aesthetic value. The introduction of LED lighting and the integration of landscaping have made facade lighting a key element in enhancing both design and security. By the 2020s, the scale and symbolic importance of main entrances have grown, incorporating environmentally friendly and high-end designs. The study predicts that future designs will prioritize sustainable main entrances incorporating smart technologies and eco-friendly lighting. This research serves as a valuable reference for planning residential complex designs and facade lighting.

http://doi.org/10.5207/JIEIE.2025.39.3.190

Jang-Hun Park ; Woo-Cheol Jeong ; Hong-Je Ryoo

In this paper, a 60kV, 6mA high-voltage DC power supply was described. The Cockcroft-Walton voltage multiplier (CWVM), commonly used in high voltage/low current applications, faces limitations in applications requiring precise voltage control due to increased output voltage ripple and voltage drop as the number of stages increases. To address these challenges, a 60kV high-voltage power supply was designed based on a phase-shifted full-bridge(PSFB) converter and a bipolar hybrid symmetrical voltage multiplier(HSVM). The PSFB converter achieves switching loss reduction through zero-voltage switching(ZVS) turn-on, making it suitable for high-frequency operation required for low voltage ripple. By adopting an HSVM, the proposed design significantly reduces output voltage ripple and voltage drop compared to conventional CWVM. Furthermore, the bipolar configuration of the HSVM enhances ripple reduction and voltage drop mitigation while ensuring easier insulation design relative to grounding. The suitability of the 60kV, 6mA high-voltage power supply design was validated through practical experiments.

http://doi.org/10.5207/JIEIE.2025.39.3.196

Jin-Sung Lee ; Jeong-Hwan Jeon ; Sang-Jun Lee ; Kyo-Beum Lee

This paper proposes a reactive power control method in grid-connected four-leg inverter for stabilizing the point of common coupling(PCC) voltage. The proposed method controls the magnitude of the reactive power output from the inverter to ensure that the PCC voltage satisfies the defined standard when the voltage at the PCC point is higher or lower than the reference value. Reactive power outputs are regulated based on the control curve for PCC voltage defined by the Korean Grid Association. A strategy to control each phase individually is required to control the PCC voltage of each phase since the magnitude of the PCC voltage can vary across phases depending on the load applied to each phase. The individual-phase control strategy is employed for the reactive power control to regulate the PCC voltage of each phase in this paper. The PCC voltage of each phase is stabilized through the reactive power control with individual-phase control when the loads on the phases are unbalanced. The validity of the proposed method is demonstrated through simulation results.

http://doi.org/10.5207/JIEIE.2025.39.3.206

Yechan Kim ; Minkyung Jeong ; Bonhyuk Ku ; Jaesang Kim ; Hyoungku Kang

Asset management in power systems is essential for ensuring grid reliability, optimizing asset performance, and supporting sustainable operations. This study examines the organizational structures and practices of asset management departments in leading international power companies, such as National Grid, SPEN (Scottish Power Energy Networks), ENWL (Electricity North West Limited), and others, to derive actionable insights for optimizing KEPCO’s (Korea Electric Power Corporation) asset management framework. Key findings highlight the integration of digital technologies (e.g., IoT, AI, big data) and the strategic positioning of asset management departments within organizations to enable real-time monitoring, predictive maintenance, and efficient resource allocation. For KEPCO, a phased implementation strategy is proposed: an initial focus on technical stabilization through collaboration with operations teams, transitioning to enhanced integration with planning functions for long-term investment strategies, and finally, establishing the department as a core entity within the executive decision-making process. The study emphasizes the necessity of a comprehensive approach incorporating digital transformation, regional asset management adaptations, and sustainable investment planning. These recommendations aim to strengthen KEPCO’s operational efficiency, support Korea’s energy transition, and achieve carbon neutrality goals.

http://doi.org/10.5207/JIEIE.2025.39.3.217

Kyung-Min Lee ; Chul-Won Park

Recently, VRES(Variable Renewable Energy Sources) such as WP(Wind Power) and PV(Photo Voltaic) systems are rapidly spreading worldwide due to energy transition policies for carbon neutrality. As VRES with IBRS(Inverter Based Resources) become widespread, the strength of complex power systems deteriorates, and so countermeasures are required. Therefore, to ensure stable operation of complex power grids, the SM(Strength Measures) must be quantified. In this paper, in order to accurately evaluate the strength of a VRES-based power grid, SM such as SCR(Short Circuit Ratio) and ESCR(Equivalent Short Circuit Ratio) are presented. After selecting the linked models consisting of PV, WP, etc., which collect various parameters and specifications, two case studies are conducted. Finally, the SM presented for the each model system are calculated, and the performances are evaluated.

http://doi.org/10.5207/JIEIE.2025.39.3.223

Dong-Yun Lee ; Nam-Kyu Ju

This paper proposes a new Automatic Transfer Switch (ATS) and its driving circuit in which a movable element including a W-shaped cam-shaft and a solenoid coil are internally configured. The proposed new Automatic Transfer Switch (ATS) is a movable bus-bar for switching the power supplied from commercial power to emergency power or from emergency power to commercial power, a movable element including a W-shaped cam-shaft, and an automatic. The solenoid coil integrated in the inside of the ATS, the brush mover connector for connecting the mover part and the solenoid coil, and the brush mover restoration spring to restore the brush mover connector, the driving circuit driven by the driving signal from the control unit and the driving circuit. The proposed ATS including a control unit for controlling the switch and a driving circuit thereof are proposed.

http://doi.org/10.5207/JIEIE.2025.39.3.230

Rui Hwa Zhang ; Jin-Uk Song ; Seong-Il Lim ; Yun-Sik Oh

This paper presents a local ID mapping method based on a connectivity matrix of power equipment to facilitate efficient data exchange in smart grid environments. The proposed method utilizes an adjacency matrix to construct the connectivity matrix that captures the shortest path between power equipment. From this matrix, a unique feature value is derived for each equipment. Local IDs sharing the same feature value are identified as representing the same equipment, enabling consistent ID mappings across different IT systems. To validate the accuracy of the local ID mapping method, a test system comprising 33 switches in a distribution feeder is employed. The case study results demonstrate that the method can accurately match multiple objects within power systems.

http://doi.org/10.5207/JIEIE.2025.39.3.236

Kyoung-Gu Lee ; Hye-Won Choi ; Kyo-Beum Lee

This paper proposes a thermal reduction method for SiC modules using discontinuous PWM (DPWM) based on power factor. Thermal management is critical to improving the reliability and efficiency of inverter systems ensuring significantly lower costs in various applications. An active thermal controls based on modulation schemes have been presented to alleviate thermal stress on the power modules while maintaining optimal power quality without additional hardware or software. The power loss and thermal stress of SiC module are analyzed according to the modulation schemes such as sinusoidal PWM (SPWM), space vector PWM (SVPWM), and DPWM in this paper. In addition, The thermal reduction of DPWM schemes at clamping regions and power factor are analyzed to reduce the thermal of the SiC module. The proposed thermal reduction method is demonstrated by various simulation results.