http://doi.org/10.5207/JIEIE.2026.40.1.1

Yeonjoo Lee ; Kyu-Sun Lee ; JinHoi Gu

This study was conducted to propose a mew assessment method to improve the limitations of the existing Light pollution environmental impact assessment, which has been restricted to localized measurements. A drone-based measurement approach was introduced to enable observations over wide areas. RGB data were extracted from optical images captured by drones and converted into single brightness values using a transformation formula. By comparing these results with ground-based luminance measurements, a calibration curve was established, allowing the development of a model capable of predicting luminance from RGB data. The proposed assessment method is expected to be highly applicable to various platforms utilizing optical information, offering improved efficiency and for light pollution evaluation.

http://doi.org/10.5207/JIEIE.2026.40.1.5

So Yeon Park ; Yong Wook Lee

In this study, we investigated the continuous wavelength tuning capability of a targeted transmission spectrum (TTS) in a polarization-diversified fiber loop multiwavelength filter based on quarter-wave polarization conversion. The multiwavelength filter consists of a four-port polarization beam splitter, two polarization-maintaining fiber segments of equal length, four quarter-wave retarders (QWRs), and one half-wave retarder (HWR). Within the polarization-diversified fiber loop structure, the HWR optimizes the multiwavelength transmission spectrum by maximizing its extinction ratio. We mathematically modeled the optical components within the filter using the Jones matrix formulation, and derived the general transmittance function of the filter from this model. Using this transmittance function, we selected a TTS at specific azimuth angles of the wave retarders. Theoretically, it was confirmed that, by adjusting the azimuth angles of the QWRs appropriately, an additional phase shift φ could be introduced into the filter’s transmittance function, which defines the TTS. This enables continuous wavelength tuning of the TTS. To verify this experimentally, the filter was constructed, and eight transmission spectra exhibiting a 0.1nm red shift between spectra were successfully obtained. This validates the continuous wavelength tuning capability of the TTS in our multiwavelength filter.

http://doi.org/10.5207/JIEIE.2026.40.1.13

Seo-Hoon Kim ; Jong-Bin Park

This study presents a comparative analysis of rule-based and predictive lighting control algorithms in commercial building environments, focusing on their responsiveness, accuracy, and energy efficiency. A full-scale indoor testbed comprising nine lighting zones was constructed, and both algorithms were applied under identical conditions over a 28-day period. The predictive control method employed a lightweight first-order Markov model to forecast user movement paths and proactively control lighting activation. Quantitative performance indicators?including CV(RMSE), NMBE, Time to Responsive Dimming (TRD), and Redundant Activation Count (RAC)?were utilized in accordance with ASHRAE Guideline 14-2023. The experimental results showed that the predictive algorithm outperformed the rule-based approach, reducing lighting error by 39.4%, improving TRD by 68%, and achieving a 15.2% reduction in energy consumption. These findings suggest that predictive control offers significant advantages in user-centric lighting management, particularly for retrofit commercial spaces and edge-device environments. This study provides a practical reference for selecting intelligent lighting control strategies that balance energy savings and user comfort.

http://doi.org/10.5207/JIEIE.2026.40.1.21

Jae-Wook Ahn ; Uh-Chan Ryu

In this study, we propose an inverse design method based on reinforcement learning for reflectors, aiming to achieve uniform light distribution on targeted surfaces, including contamination-prone air filters and concentrated photovoltaic solar panels. Conventional inverse reflector design approaches-such as differential equations, 3D vector formulas, and dedicated software-are limited by high computational complexity and the inability to implement beyond constrained structures. To overcome these limitations, we developed a reinforcement learning algorithm that rewards illumination uniformity, enabling the agent to autonomously derive the optimal reflector shape using only a few initial conditions, such as the reflector’s coordinates and distance. Through 5,000 training episodes, we obtained a reflector shape that achieved approximately 53% uniformity. Although this is lower than the 69% uniformity reported in previous studies employing 3D vector equations, it is sufficient for practical applications to air filters and solar panels, while offering the advantage of being implemented through very simple methods.

http://doi.org/10.5207/JIEIE.2026.40.1.27

Sung-Min Park

The demand for electricity is increasing significantly as the number of high-rise buildings increases on limited land in urban areas. Most of the electricity needed in the metropolitan area is supplied through the Metropolitan Tie Line. In this paper, a micro-hybrid pumped-storage power plant system using the drop of high-rise buildings in the city center is proposed to improve the reliability of the power system and increase the power independence of the city center. Therefore, an analysis was performed using the Homer model to simulate the optimal system configuration according to Variation in power load. The analysis results showed that as the power load decreases, the optimal configuration of the system also decreases. It was also confirmed that as the power load decreases, the Net Present Cost(NPC) also decreases. Micro-hybrid pumped-storage power plant system of urban high-rise buildings are expected to contribute to improving the reliability of the power system, reducing transmission constraints on flexible lines in the metropolitan area, and further increasing power independence in urban areas.

http://doi.org/10.5207/JIEIE.2026.40.1.34

Byung-Woo Kang ; Kyo-Beum Lee

This paper proposes a mitigation of motor overvoltage using P&O-based discontinuous pulse width modulation (DPWM) in motor drive systems. Voltage reflection is investigated using transmission line theory, and the mechanism of the double pulsing effect caused by voltage reflection is analyzed. The proposed method determines the occurrence of overvoltage and adjusts the discontinuous region to mitigate motor overvolatage events. The variation of the discontinuous region is studied according to the modulation index (MI). The effectiveness of the proposed method is verified through simulations.

http://doi.org/10.5207/JIEIE.2026.40.1.43

Sung-Sam Kim

In this paper, we compared and analyzed three methods to determine whether a 22.9kV MOF arrester was deteriorated. First, based on the ‘Caution’ deterioration results from the three-phase comparison method among the infrared thermal imaging diagnosis, which is a non-power diagnosis of power facilities, second, the leakage current measurement was within the normal range, although it is based on the KEPCO distribution facility leakage current judgment standard. Third, the insulation resistance measurement results of the replacement lightning arrester with a ‘Caution’ deterioration rating along with discoloration and a new product showed a difference in insulation performance of approximately 150 times. As a result, it was confirmed that the three-phase comparison method, which measures the temperature of an object in a non-contact, uninterrupted state without a power outage and uses the relative temperature difference between each phase to diagnose the presence or absence of a lightning arrester abnormality, is easy to diagnose and is practically valid in industrial settings.

http://doi.org/10.5207/JIEIE.2026.40.1.49

Changyeong Cheon ; Hyeondo Kim ; Myungchin Kim

Epoxy resins are widely used as insulating materials for high-voltage equipment due to their excellent dielectric and thermal stability, but petrochemical-based resins raise environmental concerns. To address this, bio-epoxy composites incorporating epoxidized soybean oil (ESO) were prepared by blending diglycidyl ether of bisphenol A (DGEBA) and ESO at a 7:3 ratio with 65 wt% micro-silica filler. Their electrical properties, including relative permittivity, dielectric loss tangent, electrical conductivity and AC breakdown strength, were evaluated, and accelerated stress tests were conducted to obtain lifetime data. The results were statistically analyzed using normal, Weibull, log-normal, exponential, and gamma distributions, and goodness-of-fit tests identified the most suitable model. This work demonstrates a statistical approach for assessing the electrical insulation performance of bio-epoxy composites as eco-friendly insulating materials.

http://doi.org/10.5207/JIEIE.2026.40.1.56

Ui-Chang Mun ; Seung-Ho Song

This paper proposes a method for estimating the output voltage and current of the LCC resonant converter used in a pulse power system. An equation based output estimation algorithm was derived by analyzing the operation modes of the LCC　resonant converter applied to a high voltage DC power supply. In the case of existing estimation methods, parasitic components of the circuit were ignored. However, the proposed estimation method minimizes the estimation error due to parasitic resistance by analyzing the operation mode with added resistance of the circuit. The output voltage was estimated based on the informations of DC input voltage and the resonant current, while the output current was estimated based on the information of resonant current. To verify the proposed method, the PLECS simulation program was used. As a result of simulation, The output voltage error was achieved at a maximum of 0.25% and the output current error was achieved at a maximum of 3.3%. Compared to the existing estimation method, the output voltage error was improved by 19.35%, and the output current error was improved by 29.8%, verifying the validity of the proposed output estimation method.

http://doi.org/10.5207/JIEIE.2026.40.1.64

Da-Sol Kim ; Kyo-Beum Lee

This paper presents a cell-level time-series data management structure for a cloud-based wireless battery management system. The background and necessity of continuous cell-level data collection in wireless battery monitoring environments are described. A data management framework for collecting and transmitting cell-level measurement data to the cloud is defined. The overall system architecture consisting of the battery module, wireless communication unit, and cloud-based data management layer is presented. Experimental results demonstrate the storage and visualization of cell-level battery data using the proposed system.