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분자동역학과 전산유체역학을 이용한 채널 내에서의 혼합유동에 관한 연구
이현섭(Hyunsub Lee),손기헌(Gihun Son) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
In this study, we investigate mixing phenomena of two fluids in a solid channel using Computational Fluid Dynamics(CFD) software, FLUENT. The channel diameter is varied from 1m to 0.01㎛ and its effect in the mixing phenomena is quantified. As the channel diameter decreases, the viscous force is dominant and the volume fraction of air decrease in the channel after merged. Also, we simulate the fluid mixing cases with 0.01㎛ channel size using Molecular Dynamics(MD) software, Large-scale Atomic/molecular Massively Parallel Simulator (LAMMS). The MD results are compared with the CFD results.
자동 정속 주행 차량의 변속 패턴 보정 기법 소프트웨어 개발
이현섭(Hyunsub Lee),신창우(Changwoo Shin),임원식(Wonsik Lim),차석원(Sukwon Cha),이용달(Yongdal Lee),김정욱(Jeongwook Kim) 한국자동차공학회 2013 한국자동차공학회 부문종합 학술대회 Vol.2013 No.5
Shift pattern in automatic vehicles is usually revised by actual vehicle driving which includes some information such as traction force, driving cycle, throttle opening. In order to adopt appropriate shift pattern to object vehicle, base map of shift pattern should be fixed by various road environment. However, too much time and money will be spent in utilizing handmade procedure. In this study, tuning software of auto-cruise shift pattern can calculate base map of shift pattern prior to actual or vehicle calibration. Velocity samples, cruise signals, incline values are selected from driving cycle. Then, shift patterns nearing samples can be updated by tuning logic. Appropriate driving sample can change one of shift patterns which are up or down-shift pattern.
토크 컨버터 영향을 고려한 변속 맵 결정 방법에 관한 연구
이현섭(Hyunsub Lee),신창우(Changwoo Shin),임원식(Wonsik Lim),차석원(Sukwon Cha) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5
Shift-scheduling has been developed by vehicle speed, throttle valve opening. It was supposed to be revised manually. It takes much time to do for engineers of an automotive industry. In addition, power-train components such as engine, transmission should be considered to create shifting pattern. It is important to consider characteristics of torque converter fluid. In this study, shifting schedules were selected from an engine map and a turbine map. Engine map is able to be converted to turbine map considering capacity factors of torque converter. This study is dealing with some different things between shifting schedules from both maps. Then it will discuss several effects of shift patterns, especially focusing on a turbine map.
이현섭(Hyunsub Lee),서호원(Howon Seo),임원식(Wonsik Lim),차석원(Sukwon Cha) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
When a clutch disk of 4-wheel drive vehicle get severe friction forces from transmission, slip phenomenon where friction plate is worn out will happen. This phenomenon let the clutch have a lower efficiency, and has a harmful effect for vehicle users. However, the problem we need to note is an increase of temperature related to decreasing friction coefficient which let output torque of the clutch decreased. So, it needs to be modeled for estimating increase of the clutch as 3steps. There are dynamic model, thermodynamic model, friction coefficient model. In this paper, only dynamic model is dealt with in detail. This model contains loads, mechanical factors such as any shaft, ramp, rollers, a solenoid, primary and secondary clutch to calculate how much heat generated. It is based on Matlab & Simulink program to simulate the operation of whole parts of the clutch.
전동식 조향장치의 진동특성 분석을 위한 볼-스크류 시스템의 동역학적 해석 모델 개발
이현섭(Hyunsub Lee),정춘화(Chunhua Zheng),유민우(Minwoo Ryu),임원식(Wonsik Lim),차석원(Sukwon Cha) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
Electronic power steering(EPS) uses auxillary power of electric motor when steering wheel is rotated and has several advantages compared to hydraulic power steering. It is lighter than hydraulic power steering and has the effect of fuel saving. It also can make vehicle engine not to generate much heat. However, electronic power steering has a problem with noise, oscillation in ball-screw system. Ball-screw system generates much noise when collision occurs between a ball and a ball saver. In this paper, it figures out the trace of a ball of spiral movment and initial velocity before entering into ball saver. Then, it analyzes how to generate much noise, oscillation and how much to be generated.
이현섭(Hyunsub Lee),신창우(Changwoo Shin),임원식(Wonsik Lim),차석원(Sukwon Cha) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
Shift pattern in automatic vehicles is usually revised by handmade procedure which includes some information such as traction force, driving cycle, throttle opening. In order to adopt appropriate shift pattern to object vehicle, base map of shift pattern should be fixed by various road environment. However, time and money can be wasted too much utilizing handmade procedure. In this study, automatic control logic is introduced to change base map of shift pattern instead of handmade procedure. Samples of constant velocity and increased velocity are selected from driving cycle. Then, shift patterns nearing samples are changed by control logic. One sample can change one of shift patterns which are up or down-shift pattern.