• Journal of Mechanical Science and Technology
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• 제14권3호
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• pp.283-290
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• 2000

To maintain the specific volumetric efficiency of a heavy-duty diesel engine, an understanding of the behavior of each part of the valve train system is very important. The stiffness of the valve train system has a strong influence on the behavior of the valve train than valve clearance, heatresistance, or the durability of parts. In this study, a geometrical cam design profile using a finite element model of the valve train system is suggested. The results of the valve behavior according to the change in stiffness is analyzed for further tuning of the valve train system.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제28회 추계학술대회
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• pp.30-37
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• 1998

It is well known that reduction of friction loss due to the valve train system greatly affects on improvement of fuel economy in internal combustion engine. In order to investigate friction characteristics of valve train system we carried out friction force measurement using test rig developed by ourselves. From test results, we concluded that characteristics of lubrication and friction torque on the valve train system such as mixed and hydrodynamic was mainly governed the contact type between cam and tappet.

• 대한기계학회논문집B
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• 제26권10호
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• pp.1364-1369
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• 2002

This paper introduces the development of the analysis and design program of valve train system. In order to verify the stability of design and improve the performance of system efficiently, it is required that integrated and interactive simulation program. The presented program is developed in the base of the object-oriented, capsulation, modulization, OLE (objected linking and embedding) and various design theory. It contains the expandability and flexibility of the structure. In addition to that, it is programmed to make the convenient user interface by using the visualization programming. This program can support the modification of the valve element as well as the development of the valve train system in the beginning of design. It is expected to save the cost and time for the design of valve train system.

• 한국자동차공학회논문집
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• 제6권3호
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• pp.78-87
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• 1998

A dynamic model of direct-acting OHC valve train system has been used to determine the load conditions in the system. The modified equations for calculating the friction forces between cam and HLA, and at a camshaft bearing have been defined considering the lubrication conditions. Then, to understand the frictional characteristics in the system, a parameter study has been performed. As the results of the analysis, valve spring stiffness and preload have great effects on the friction in the system, but the effects of other parameters are negligible. So, how to design the valve train system with respect to the reduction of friction is to minimize the valve spring stiffness and preload in the limit of satisfying the dynamic constraints.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제31회 춘계학술대회
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• pp.258-262
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• 2000

This paper reports on the development of the analysis program of the valve train system, IV-TAP. It is essential to verify the stability of the design and to improve the performance of the system. In order to do that effi챠ently, it is required that integrated and interactive simulation analysis program. IV-TAP is developed in the base of the object-oriented, capsulation, modulization, OLE(objected linking and embedding) and variational design theory. So it contain the expandability and flexibility of the structure. In additon to that, it is programed to make the convenient user interface by using the visualization programming. It can support the modification of the valve element as well as the development of the valve system in the beginning. It is expected to reduce the money and effort for design the valve train system.

• Journal of Mechanical Science and Technology
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• 제16권6호
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• pp.776-784
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• 2002

We have performed experimental studies for the improvements of pneumatic brake systems of freight trains. Currently, most of the freight trains operated by the Korean National Railroad have either empty-load or diaphragm type brake systems. In this study, appropriate methods that the air pressure characteristics in both type of brake systems are in accordance with each other have been investigated. We have also performed running tests using a 30 car-train set to design optimum capacity of a quick release valve. The test results show that the quick release valve is considerably effective in shortening the release time of the diaphragm type brake system. In the case of a normal brake application, the diaphragm type brake system with the quick release valve reduces the release time to 34% of that of the system without the quick release valve. This release time is almost equivalent to that of the empty-load type brake system. Accordance of braking performance in different types of brake systems in a train set is expected to prevent wheel flats and to reduce maintenance costs.

• 대한기계학회논문집B
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• 제25권12호
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• pp.1739-1747
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• 2001

Experimental study has been conducted to clarify the pneumatic characteristics of brake system for freight train and enhance the performance of diaphragm valve. Empty-load and diaphragm valves are installed in pneumatic brake system for freight trains of KNR (Korean National Railroad). Experiments are conducted by using freight train and diesel locomotive in operation. From the experimental results. new quick release valve shortens release time after brake application. In case of normal brake application, the release time is shortened to 34% of the original diaphragm valve. Reducing the release time of pneumatic brake system will be helpful to assure brake-release application and save maintenance efforts like wheel grinding.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제30회 추계학술대회
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• pp.318-322
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• 1999

An analytical study about dynamic behavior of center pivot rocker arm type valve train system equipped with roller of diesel engine is developed. At first, a mathematical model for the dynamic analysis has been set up using the lumped parameter method. In that model, valve spring is divided as some mass elemehts so as to simulate spring surging, Then, how the design parameters, such as valve mass, rocker arm inertia, valve spring stiffness, and initial load on valve spring, affect valve dynamic behavior especially in the valve close area is scrutinized.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제27회 춘계학술대회
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• pp.286-291
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• 1998

The aim of this paper is to measure the tappet rotation in OHC valve train system. Tappet is eccentric from the cam center to rotate for preventing the partial wear. The experimental system is developed to measure the tappet rotation by using the laser beam and optical fiber. The characteristics of tappet rotation is presented for various operating conctitions. Specially, it is observed that tappet is rotated at the base circle.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제28회 추계학술대회
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• pp.75-81
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• 1998

It is very important to evaluate the friction force of valve train system in the aspect of reducing friction loss of engine. To this end, we have developed measuring system of friction force of engine valve train system. There were two major factors in the process of development of it. One was it had to accurately measure the friction force up to 3500 Crpm without any problems such as mechanical vibration, electrical noise and so on. The other was it also had to simulate real engine conditions such as Crpm, oil temperature, oil pressure and oil aeration including effect of belt drive system. In this paper we have introduced the process of development of it based on test results, and also analysis process of measured data.