• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.5
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• pp.134-141
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• 2005

Semi-Spherical Continuously Variable Transmission(SS-CVT) is the CVT which transmits power by rolling friction between dry metals, and its outstanding advantage is the ability of realizations of neutral, forward and reverse states without relying on any other devices. A spherical shaped variator transmits power and also changes gear ratio where keeping contact with a output disk. The frictional direction to transmit power and the other direction to change gear ratio are perpendicular to each other, so we can describe that two dimensional rolling friction is occurred in the contact point between the variator and the disk. Since magnitudes or relations of the two forces are completely unknown, they were analyzed by the experiments in this study. We determined the variables related with the friction phenomena by the dimensional analysis, and manufactured the SS-CVT test bench which could measure the related variables. Finally, the empirical formula for evaluating the two friction forces was proposed based on the experimental results.

• Journal of the korean Society of Automotive Engineers
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• v.18 no.3
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• pp.8-16
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• 1996

차량의 주행저항에 대응하여 최소-최대변속비 사이를 연속적으로 무한대의 단계로 변속시킴으로써 우수한 동력성능과 연비를 얻을 수 있다는 장점을 지닌 무단변속기의 벨트-풀리 시스템에 대하여, 현재 개발에 성공한 벨트-풀리 시스템의 특징을 분석하고, 벨트 효율 및 적용한계를 조사분석한 결과, 내구성 및 소음측면에서 볼 때 금속푸시벨트가 가장 유리하며, 벨트의 동력손실을 최소화하기 위하여 금속푸시벨트의 구성부품인 블록과 링을 최적화하고, 풀리에 작용하는 축력을 최적으로 제어함으로서 전달효율이 향상된 벨트-풀리 시스템을 제공할 수 있다. 날로 엄격해지는 배기가스 규제와 전자 및 제어분야의 발달로 성능이 더욱 향상된 무단변속기의 개발 및 장착이 환산될 것으로 예상되며, 또한 효율, 소음측면 뿐만 아니라, 제작단가가 저렴한 CVT용 벨트의 개발이 잇따를 것으로 전망된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.2
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• pp.963-969
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• 2015

Bicycle is one of the most popular mode of transport due to the increase of interest in the well-being and environment pollution. Before fabricating a continuously variable transmission that is applied to the actual bicycle, for reducing the problems in the early stage, the reliable simulation program has been applied and the financial problem can be solved. In this paper, in order to confirm the design factor, the stress analysis has been applied. In all models, each link and the joint portion are assumed to be a major design factors, and impact of each link and joints received stress during the operation and it is confirmed by using the CAE. Also, for the analysis region, the special code has been developed to calculate pulsation phenomenon through appropriate mathematical modeling.

• Journal of Biosystems Engineering
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• v.38 no.3
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• pp.171-179
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• 2013

Purpose: A simulator for the design and performance evaluation of a tractor with a hydro-mechanical transmission (HMT) was developed. Methods: The HMT consists of a hydro-static unit (HSU), a swash plate control system, and a planetary gear. It was modeled considering the input/output relationship of the torque and speed, and efficiency of HSU. Furthermore, a dynamic model of a tractor was developed considering the traction force, running resistance, and PTO (power take off) output power, and a tractor performance simulator was developed in the co-simulation environment of AMESim and MATLAB/Simulink. Results: The behaviors of the design parameters of the HMT tractor in the working and driving modes were investigated as follows; For the stepwise change of the drawbar load in the working mode, the tractor and engine speeds were maintained at the desired values by the engine torque and HSU stroke control. In the driving mode, the tractor followed the desired speed through the control of the engine torque and HSU stroke. In this case, the engine operated near the OOL (optimal operating line) for the minimum fuel consumption within the shift range of HMT. Conclusions: A simulator for the HMT tractor was developed. The simulations were conducted under two operation conditions. It was found that the tractor speed and the engine speed are maintained at the desired values through the control of the engine torque and the HSU stroke.

• Advances in Automotive Engineering
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• v.1 no.1
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• pp.105-121
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• 2018

The hybrid electric powertrain is a robust solution that allows for major improvements in both fuel economy and emission reduction. In the present study, a through-the-road hybrid vehicle model with an electric motor driving the rear axle and an Internal Combustion Engine (ICE) driving the front axle has been constructed. We then present a systematic method for the determination of a real time applicable optimal Energy Management Strategy (EMS) for a hybrid road vehicle. More precisely, we compare the performance of rule-based EMS strategies to an optimization-based strategy, namely ECMS (Equivalent Consumption Minimization Strategy). The comparison is conducted in parallel with a parameterization of the size of the internal combustion engine and the implementation of a Continuously Variable Transmission (CVT) that allows following the line of best fuel economy. For the FTP-75 driving cycle, the constrained engine On-off control algorithm is shown to offer a 28% improvement potential of fuel consumption compared to the conventional internal combustion engine while the ECMS strategy achieves an improved potential of nearly 33%.