• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1022-1027
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• 2008

This paper represents a study on the conceptual design of new automatic bicycle transmission. The gear change in a commercial bicycle is carried out by moving the chain between sprockets. By the use of a multiple sprocket for speed change the power loss and transmission shock may occur. To solve the problem of bicycle transmission, the improved solution was derived by the technical contradiction matrix of TRIZ. The conceptual solution is one sprocket which replaces the function of multiple sprockets and adapts actively to the pitch of chain. And it was confirmed to be an adequate design through the Independence Axiom of design axiom.

• 한국자동차공학회논문집
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• 제5권3호
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• pp.172-181
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• 1997

The dynamic characteristics during gear ratio change including the disturbance of output torque has been one of the most important issues in the study of automatic transmissions of passenger cars. In this paper, to investigate the dynamic characteristics of a passenger car automatic transmission during gear ratio change, a dynamic model of the driveline of a passenger car focused on the automatic transmission is proposed and the dynamic simulation program is developed. The results of the simulation show good agreements with the experimental data, which process the use fullness of the dynamic model and the simulation of the driveline.

• 한국자동차공학회논문집
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• 제5권6호
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• pp.36-43
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• 1997

To cope with quest to improve the fuel economy and vehicle performance, Continuously Variable Transmission with Changing the speed ratio between minimum and maximum ratio by infinite step, is more efficient than conventional multi-ratio transmission. In this paper, to investigate a specific CVT shift ratio diagram and CVT shift characteristics, CVT vehicle was tested on the proving ground and chassis dynamometer. The test results are as follows; CVT can obtain the excellent vehicle performance and fuel economy changing the shift ratio by infinite step, without rapid change of engine revolution and driving force. And CVT can set up a special shift range that obtains not only the engine brake effect but also the maximum speed driving.

• 한국자동차공학회논문집
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• 제3권6호
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• pp.212-223
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• 1995

To improve the efficiency of a power transmission system with slip elements, power split/circulation system is applied. The performance of a power split/circulation system varies widely by the change of the followings; the layout of system, the type and gear ratio of planetary gear, the performance of slip element, etc. Therefore, when one designs such a power transmission system or when one determines the economic/power mode of system, a certain performance prediction method is needed. In this study, the internal power flow pattern of a power split/circulation system is theoretically analyzed on several transmission systems. And an effective performance prediction method(so called performance locus diagram) is presented. By this method, the effects of design factors can be easily understood and the qualitative performances of system can be clearly evaluated.

• 한국자동차공학회논문집
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• 제12권6호
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• pp.175-181
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• 2004

This paper presents the main method to analyze the dynamic characteristics of power transmission system using the multi-body dynamics, which is based on the concept of subsystem equation, subsystem assembling, and the self-determination technique for the system degree of freedom. We can model the mechanical components of power transmission system easily with the advantage of multi-body dynamics. Based on the theory, a dynamic simulation program was developed to analyze system performances, transient phenomena, and other dynamic problems. The driving performance of automatic transmission was simulated with using the multi-body dynamics and Newtonian method, and the validity of program was proved by comparing the two kinds of result.

• International Journal of Automotive Technology
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• 제8권5호
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• pp.593-598
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• 2007

A new continuously variable transmission for bicycles(B-CVT) is developed by using a traction drive mechanism having inner and outer spherical rotors. The B-CVT has high power efficiency, large torque capacity, improved drivability and good packageability. The ratio change mechanism for the B-CVT is very simple, in contrast with other traction drive CVTs. After completing a conceptual design, a performance analysis and a detail design, a prototype of the B-CVT has been manufactured. The prototype has rated power of 100 watts, pedal speed of 6 rad/s and an overall speed ratio of 1.0-4.0. A bench test and an actual bicycle test have been performed to verify the practicability of the B-CVT.

• International Journal of Automotive Technology
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• 제6권5호
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• pp.467-473
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• 2005

A continuously variable transmission (CVT) with an inner spherical traction drive was conceptually designed for bicycle usage. The range of the overall speed ratio is from 1.0 to 4.5. The rated power and pedal speed are 100 Watts and 6 rad/s, respectively. The peculiar packageability, high-level power efficiency and high torque capacity were considered in the design process. A compact CVT that can be installed within a $244\times125\times160mm^3$ space and is above 0.9 in efficiency for the rated values was numerically designed. The distribution of efficiency according to the input torque and input speed were calculated. Gradeability in the prescribed operation mode was simulated.

• 한국자동차공학회논문집
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• 제9권6호
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• pp.143-151
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• 2001

During the past several years, the major interests of car manufacturers in development of automatic transmission were in durability and shift quality. However, a large number of researches for improving shift quality that are based on dynamic characteristics of shifting mechanism have been rarely adopted in the developing process because it is quite difficult to predict the shifting performance from the dynamics simulation. One of the important reasons for the difference between simulation results and experiments arises from the automatic transmission hydraulic system that consists of many valves with high order model and shows a lot different dynamics to temperature variation. In this work, hardware-in-the-loop simulation system for automatic transmission was developed f3r improving the accuracy of simulated result by combining the real-time simulation model with the real hydraulic system. The real-time simulation for automatic transmission model excluding hydraulic system is executed with TI's TMS320C31 DSP and the interfacing board which includes 12bit A/D, PWM signal generator and driver, serial driver ,etc is designed for acquiring the simulation data and signal interface with hydraulic system. We verified the proper operation and correctness of shifting result by comparing the off-line simulation result with that of HILS and experimental result which was performed on transmission dynamometer driven by electric motor.

• 한국자동차공학회논문집
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• 제14권1호
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• pp.176-182
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• 2006

In this paper, we have measured the power of the electro-magnetic waves in the cabin of automobiles with automatic transmission or manual transmission. Measured frequency ranges are $815\~865MHz\;and\;900\~950MHz$. Experimental studies are conducted by measuring the radiated power of the frequency spectrum for above frequency bands. The $\lambda/2$ dipoles used for measurement are fabricated to comply with the COMMISSION DIRECTIVE 95/54/EC. Experimental results confirm that the level of radiated power in the cabin of automobile with automatic transmission is higher than that with manual transmission. The measured values are less than -85dBm for the manual transmission vehicles, but more than -79dBm for the automatic transmission vehicles.

• 한국자동차공학회논문집
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• 제25권2호
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• pp.250-256
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• 2017

Automatic transmission(A/T) is one of a car's core components. The durability of A/T has an effect on the durability of the car. The input shaft of A/T passes the power directly from the engine, so the durability of the input shaft for A/T is likewise vital. In this study, the test method of the input shaft is considered and the load spectrum of A/T is analyzed to secure durability of the input shaft. The shape parameter, T-N curve of the input shaft torsional fatigue test are obtained for life evaluation and analysis. Results of this study can be used to get the basic background of the durability test for A/T components.