Ki Jun Kim

For the first time, we report the possibility of utilizing Li2CoPO4F as a novel cathode material for hybrid capacitor applications. Li2CoPO4F powders were prepared by a conventional two-step solid state method. A hybrid cell was fabricated using Li2CoPO4F as the cathode along with activated carbon (AC) as the anode in 1 M LiPF6 dissolved in 1 : 1 EC/DMC electrolyte and its electrochemical properties were examined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and consta

The present work focuses on the synthesis of lithium ionic conductors based on a Li2S-Al2S3-GeS-P2S5 system due to the high ionic conductivity exhibited by the constituents of this system. Mechanical milling for a short duration and a single step heat treatment at a moderate temperature of 550 °C resulted in crystalline powders with high lithium ionic conductivity at room temperature that are comparable to the organic liquid electrolytes. The effect of various aluminum to germanium ratios was st

In general, conventional high-Tc superconducting fault current limiters (SFCLs) are operated by cooling systems with a liquid cryogen, such as liquid nitrogen (LN2). However, in the fault mode, LN2 evaporates because of joule heating in the SFCL module, so the SFCL system experiences an enormous increase in nitrogen gas volume. In this case, the thermal stability and protection of the system become the primary concerns for the design of the SFCL cooling system. In order to enhance the thermal st

The high voltage cathode material, Li₂CoPO₄F was successfully synthesized and coated with various amounts of Al₂O₃ for enhanced electrochemical performance.

This paper presents the novel control method of the Four-Switch Buck-Boost (FSBB) converter for Super Capacitor Pre-Charger (SCPC) in hydrogen electric vehicles. The method is proposed to improve voltage regulation characteristic during super capacitor pre-charging, and is able to maintain continuity of duty ratio and voltage conversion ratio. Even though operation mode changes for achieving unity voltage gain, the additional switch state diminishes voltage fluctuation at transition point compar

An area efficient scheme for WCDAC (Weighted Capacitor Digital-to-Analo g Converter) is proposed. This new architecture adopts an extensive charge-sharing scheme to enhance the overall converting resolution without additional increase of the capacitor distribution ratio. The validity of the approach is clearly proved by the analytic method and simulations.

This study utilized four image-generating AIs-ChatGPT, DALLE, MidJourney, and Firefly-to create poster designs by adapting Shepard Fairey's Hope poster style to selected members of BTS.The study outlines the characteristics and utilization steps of each AI tool as follows.First, through prompt refinement with ChatGPT, DALLE was able to generate images resembling the actual appearance of BTS members.The limitations of DALLE in directly specifying certain individuals or styles were addressed by em