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최욱진,조희재,윤경민,민경환,임남형,이수열,Choi, Wookjin,Cho, Hui Jae,Yun, Kyung-Min,Min, Kyung-Hwan,Lim, Nam-Hyoung,Lee, Soo Yeol 한국재료학회 2017 한국재료학회지 Vol.27 No.12
The use of continuous welded rail is increasing because of its many advantages, including vibration reduction, enhanced driving stability, and maintenance cost savings. In this work, two different types of continuous welded rails were examined to determine the influence of repeated wheel-rail contact on the crystal structure, microstructure and mechanical properties of the rails. The crystal structure was determined by x-ray diffraction, and the microstructure was examined using optical microscopy and scanning electron microscopy. Tensile and microhardness tests were conducted to examine the mechanical behaviors of prepared specimens taken from different positions in the cross section of both newly manufactured rail and worn rail. Analysis revealed that both the new and worn rail had a mixed microstructure consisting of ferrite and pearlite. The specimens from the top position of each rail exhibited decreased lamella spacing of the pearlite and increased yield strength, ultimate tensile strength and hardness, as compared with those from other positions of the rail. It is thought that the enhanced mechanical property on the top position of the worn rail might be explained by a mixed effect resulting from a directional microstructure, the decreased lamella spacing of pearlite, and work hardening by the repeated wheel-rail contact stress.
차량 선형 제어를 위한 Solenoid Valve 성능 특성에 대한 연구
최욱진(Wookjin Choi),이상철(Sangcheol Lee),이충재(Chungjae Lee) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Mando's ABS System includes Traction control Magnetic force control (TCMF) system. The TCMF system is a solenoid valve control method, which makes valve to react linearly according to electric current supplied to achieve optimal hydraulic force. This allows the function of complex hydraulic system to be at limiting conditions such as various flow patterns and air-gap conditions.
최욱진(Wookjin Choi),이상철(Sangcheol Lee),노강성(Kangsung Noh),손일국(Ilguk Son) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In the process of developing HCU (Hydraulic Control Unit) of MANDO ESP (Electrical Stability Program) System, several designs of pump are suggested. There are many ways to improve the performance of a pump, nevertheless, several parameters are considered to optimize the performance in this study: spring constant, and shape of Spring Support. In order to analyze performance of pump in each case, two-dimensional CFD analysis is conducted. The main interest in this study is in change of pressure inside the piston assembly and outlet valve assembly during the Pumping operation.
Dynamic Brake System 유압 시뮬레이션 모델 개발
전재영(Jaeyoung Jeon),서정욱(Jungeuk Seo),조근형(Keunhyung Cho),최욱진(Wookjin Choi) 한국자동차공학회 2023 한국자동차공학회 부문종합 학술대회 Vol.2023 No.5
The IDB(Integrated Dynamic Brake) is a system designed to control the braking force of a vehicle in order to decelerate the vehicle speed according to the intention of the driver, not the service brake system. The IDB is a system that integrates the separate Master, Booster, and ESC(Electronic Stability Control). Since the IDB is a complicate integrated system, behavior of each component has impact on the system performance. For this reason, predicting the failure of main components in the process of developing the system has become an important challenge. This study introduces an analysis model that verifies the flow of hydraulic pressure in the failure situation of the solenoid valves, which are important components in the IDB. Therefore, this study aims to analyze IDB system behavior through preliminary predictions of the two situations of permanent open and close in the solenoid valve