• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.435-439
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• 2002

In the pneumatic system, pneumatic cylinder is wildly used to factory automation. In general, Pneumatic cylinder problems are occured with colliding to stroke end part at which piston collide to end-cap, head cap and tube when piston is loading. This appearances have a short life of cylinder and is due to system destruction. This study examines the dynamic characteristics of pneumatic cushioning cylinder and cushion sleeve design. At head part cushion chamber for the vertical experimental, The decisions of cushioning effect and the results of the experimental research are obtained to the followings: i) The cushioning effects could acqure to the reserch, if the compressible energy is more than kinetic ones. ii) The collision of piston and head cover could acqure to the research, if the kinetic energy is more than compressible iii) If the load increase to the rolling car, the cushion region pressures would increase and the dynamic force.

• 한국자동차공학회논문집
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• 제14권1호
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• pp.92-99
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• 2006

The swirl ratio of a charge in the cylinder was estimated by calculating the ratio of the rotary speed of charge which could be simulated from the rotary speed of paddle in the swirl measurement apparatus, to the engine speed which could be calculated by measuring intake air flow rate. The automation of the swirl ratio measurement for cylinder head was achieved by controling both valve lift in cylinder head and a suction pressure of surge tank using two step-motors. The number of measurement position for calculating mean swirl ratio was varied by adjusting the interval of valve lift. The mean swirl ratio with varying the number of measurement position showed nearly constant value. Two measurement methods for measuring the swirl ratio were compared, one was to control the suction pressure of the surge tank with PID (proportional, integral, differential) mode with by-pass valve controlled by the step motor and the other did not control the surge tank pressure by fixing the by-pass valve. The difference of the mean swirl ratio between the two measurement methods showed nearly constant value with varying the number of measurement position. This means that the w/o PID control method could be preferred to the PID control method which has been used, due to the simpleness of the swirl measurement.

• Corrosion Science and Technology
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• 제14권6호
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• pp.288-295
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• 2015

The present work addresses crevice and galvanic corrosion processes occurring at the cylinder head gasket/cylinder head interface and cylinder head gasket/cylinder liner interface of four-stroke medium-speed diesel engines for marine applications. The contact between these systems and the marine environment can promote formation of demanding corrosion conditions, therefore influencing the lifetime of the engine components. The electrochemical behavior of various metals and alloys used as head gasket materials (both ferrous alloys and copper alloys) was investigated. The efficacy of corrosion inhibitors was determined by comparing electrochemical behavior with and without inhibitors. In particular, crevice corrosion has been investigated by electrochemical tests using an experimental set-up developed starting from the requirements of the ASTM G-192-08, with adaptation of the test to the conditions peculiar to this application. In addition to the crevice corrosion resistance, the possible problems of galvanic coupling, as well as corrosive reactivity, were evaluated using electrochemical tests, such as potentiodynamic measurements. It was possible to quantify, in several cases, the corrosion resistance of the various coupled materials, and in particular the resistance to crevice corrosion, providing a basis for the selection of materials for this specific application.

• International Journal of Automotive Technology
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• 제7권1호
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• pp.109-114
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• 2006

Half-beads of multi-layer-steel cylinder head gaskets take charge of sealing of lubrication oil and coolant between the cylinder head and the block. Since the head lifts off periodically due to the combustion gas pressure, both the dynamic sealing performance and the fatigue durability are essential for the gasket. A finite element model of the halfbead has been developed and verified with experimental data. The half-bead forming process was included in the model to consider the residual stress effects. The model is employed to assess the dependence of the sealing performance and the fatigue durability on the design parameters of half-bead such as the width and height of bead and the flat region length. The assessment results show that the sealing performance can be enhanced without significant deterioration of the fatigue durability in a certain range of the half-bead width. In the other cases the improvement of sealing performance is accompanied by the loss of the fatigue durability. Among three parameters, the bead width has the strongest influence.

• 한국자동차공학회논문집
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• 제11권1호
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• pp.32-41
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• 2003

For the countermeasure of expected higher thermal load in miller cycle engine, coolant flows in the cylinder head of base engine with several coolant flow methods and drilled hole passages were measured by using PIV technique. And the cooling effect was evaluated by measurements of wall temperatures according to each coolant flow method. It was found that the series flow system was most suitable among the discussed 3 types of coolant flow methods since it had the best cooling effect in cylinder head by the fastest coolant flow velocity It was also found that for drilled water passage to decrease the large thermal load in exhaust valve bridge, nozzle type is more effective compared with round type of water passage, and its size has to be determined according to the coolant flow pattern and velocity in each cylinder.

• 한국자동차공학회논문집
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• 제7권5호
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• pp.89-95
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• 1999

In this study, the corrosion resistance of the aluminum casting commercial materials used in the automotive engine parts with respect to the anti-freeze coolant environment has been tested by the potentio dynamic method. especially, the effect of borax additive in engine coolant on the corrosion resistance of the aluminum casting materials has been evaluated. It was found that the borax in commercial engine coolant, used to prevent the corrosion in cast iron engine, causes a pit corrosion of aluminum casting materials at high temperature. During the engine endurance test with the coolant containing borax, the aluminum cylinder head was failed by the pitting corrosion near the exhaust port. Conclusively, it was suggested that the use of borax in the anti-freeze coolant be restricted for the automotive with aluminum cylinder head.

• 한국자동차공학회논문집
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• 제6권1호
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• pp.59-72
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• 1998

This experimental study was carried out to investigate the characteristics of the in-cylinder eccentricity swirl flow generated by a 4 valve cylinder head with a tangential and a helical intake port. the measurements of the in-cylinder velocity field have been made by a two-channel LDA system. The mean flow coefficient(Cf(meam)), swirl ratio(Rs) and mass flowrate with valve eccentricity ratios and an intake port partition between the two intake ports were measured in the steady flow test fig using the ISM(impulse swirl meter). The experimental results indicated that the mass flowrate through the tangential intake port was 19% and 7.7% more than that of the helical intake port in case of with and without intake port partition respectively. There was a tendency to be a single rotation flow in swirl flow fields formed by a 4 valve cylinder head because of the interaction between the two intake ports. As the intake port partition was not set between flow coefficient(Cf(mean)) was 7.35%.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1996년도 추계학술대회 논문
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• pp.126-132
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• 1996

This study is pre-research to evaluate the reasonability of convertion aluminum alloy cylinder head cover into plastic cylinder head cover using finite element analysis. The basedata which are needed in design are shown. On processing the study size of mesh and kind of elements are varied and adaptiv method is used.

• 한국자동차공학회논문집
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• 제6권3호
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• pp.1-10
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• 1998

In this paper, we investigated the improvement of characteristics of knock, emission and fuel consumption rate by optimizing the location and size of water transfer holes in cylinder head gasket without change of engine water jacket design itself. The cooling system was modified in the direction of reducing the metal temperature in the head and increasing the metal temperature in the block. The optimization of water transfer holes in cylinder head gasket was obtained by "flow visualization test". The water transfer holes were concentrated in front side of the engine in order to reduce thermal boundary layer in the water jacket of No. 2 and No. 3 combustion changer in the cylinder head, which would have a large knock intensity, and increase thermal boundary layer in the water jacket of the cylinder block. When the modified coolant flow pattern was applied as proposed in this paper, the knock characteristic was improved. The spark timing was advanced up to 2$^{\circ}$ in low and middle speed range at a full load. In addition, HC emission at MBT was reduced by 5.2%, and the fuel consumption rate was decreased up to 1% in the driving condition of 2400 rpm and 250 KPa. However, since this coolant flow pattern mentioned in this paper might deteriorate the performance of vehicle cooling system due to the coolant flow rate reduction, a properly optimized point should be obtained. obtained.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.321-325
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• 2000

Gasket of vehicle engine maintains airtight between cylinder head and engine block under high temperature and pressure, and plays important role in heat conduction of engine. And the characterization of the nonlinear behavior of metal gasket fer various bead shapes is very important as basic research for estimation of gasket durability. But it is very difficult to analyze the behavior of gasket In real experiment. In this paper, to analysis effects of the bead shape on the nonlinear behavior of cylinder head gasket under uniform pressure, the virtual experiment using the nonlinear finite element method was performed. Results are analyzed with residual deformation and the sealing pressure. With the increase of the height and the width of bead, the residual deformation and the sealing pressure increase. And if the height is very high and the width is very narrow, the wrinkles are occurred in the gasket while working.