• 한국분무공학회지
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• 제9권4호
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• pp.46-52
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• 2004

An LPG engine (KL6i) for heavy duty vehicle has been developed using liquid phase LPG injection (LPLi) system, which has regarded as one of next generation LPG fuel supply systems. For the KL6i engine, lean burn technology was introduced to minimize the thermal loading and NOx emissions due to an increase of the engine power. In this work, injection timing and piston bowl shape were investigated for the stabilization of lean burn characteristics. Experimental results reveals that fuel stratification induced by these parameters is most effective strategy to extend lean combustion limit in the LPLi system.

• 한국정밀공학회지
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• 제13권4호
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• pp.152-162
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• 1996

The purpose of this study is the development of a lathe which can cut any pistons of oval shape with high speed, accuracy and precision by CNC (Computer Numerical Control) method. Y axis which is the position determinating mechanism with high speed response was added to the CNC lathe and the ovality and profile was cut under the control of C-Y-Z axes at same time. In the case of ovality of .phi. 0.2mm, the productivity can be improved up to 2500rpm(Y axis:83Hz) by high speed cutting than modeling method. Since a personal computer is used, it is easy to change the shape of pistion and can be applied promptly to many types of piston shppe by only changing data files.

• International Journal of Automotive Technology
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• 제7권5호
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• pp.585-593
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• 2006

The effect of the shape of the side wall on vaporization and fuel mixture were investigated for the impinging spray of a direct injection(DI) gasoline engine under a variety of conditions using the LIEF technique. The characteristics of the impinging spray were investigated under various configurations of piston cavities. To simulate the effect of piston cavity configurations and injection timing in an actual DI gasoline engine, the parameters were horizontal distance from the spray axis to side wall and vertical distance from nozzle tip to impingement plate. Prior to investigating the side wall effect, experiments on free and impinging sprays for flat plates were conducted and these results were compared with those of the side wall impinging spray. For each condition, the impingement plate was located at three different vertical distances(Z=46.7, 58.4, and 70 mm) below the injector tip and the rectangular side wall was installed at three different radial distances(R=15, 20, and 25 mm) from the spray axis. Radial propagation velocity from spray axis along impinging plate became higher with increasing ambient temperature. When the ambient pressure was increased, propagation speed reduced. High ambient pressures tended to prevent the impinging spray from the propagating radially and kept the fuel concentration higher near the spray axis. Regardless of ambient pressure and temperature fully developed vortices were generated near the side wall with nearly identical distributions, however there were discrepancies in the early development process. A relationship between the impingement distance(Z) and the distance from the side wall to the spray axis(R) was demonstrated in this study when R=20 and 25 mm and Z=46.7 and 58.4 mm. Fuel recirculation was achieved by adequate side wall distance. Fuel mixture stratification, an adequate piston cavity with a shorter impingement distance from the injector tip to the piston head should be required in the central direct injection system.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2006년도 PARALLEL CFD 2006
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• pp.268-270
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• 2006

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.409-410
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• 2002

In order to measure the oil-film pressure in sliding surface of machinery, we have developed a piezo-resistive type thin-film pressure sensor. To reduce the measurement error due to temperature and strain, the constituent of the pressure sensitive alloy was optimized and a new sensor shape was devised. In this study, we present the measurement results of the oil-film pressure distribution in engine connecting rod big-end bearing and piston pin- bosses with 3 different pin-boss shapes using the newly developed thin-film pressure sensor.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.769-772
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• 2009

Diaphragm compressors are used for a hydrogen compression because it can achieve high gas pressure with high purity. But diaphragm's lifetime may depend on the shape of the cavity and deflection from fluctuation the pressure change, which is necessary to monitored. In this study, the gas and hydraulic oil pressure in the cavity were measured as piston speed varies for diaphragm compressor. The results show pressure change quantities were reduced and maximum pressure points are delayed as the piston moves faster. And the hydraulic pressure were elevated as gas pressure elevated. And the compression period was more faster than expansion period.

• 한국산업융합학회 논문집
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• 제7권2호
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• pp.153-159
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• 2004

The purpose of this research is to investigate the performance of swirl combustion chamber diesel engine by changing the jet passage area, the depth and shape of the piston top cavity (main chamber). The performance of diesel engine with newly changed swirl combustion chamber was tested through the experimental conditions as engine speed, load and injection timing etc. The test results were compared and analyzed. And another purpose of this research is to make a new diesel engine that is satisfied fuel consumption and regulation value of exhaust gas. 1. The rate of fuel consumption was affected significantly by the jet passage area at the high speed and load than low speed and low load. The influence of jet passage large area was proven to decrease the rate of fuel consumption. 2. Smoke was affected significantly by the depth of the piston top cavity, but exhaust temperature and the rate of fuel consumption wasn't affected. The rate of fuel consumption was affected by changing injection timing. 3. The rate of fuel consumption, exhaust temperature and Smoke were affected significantly by the shape of the piston top cavity from rectangular to trapezoid. That is we have all high value. The exhaust smoke density and exhaust gas temperature depended sensitively on variation of the injection timing rather than the shape of the combustion chamber within the experimental conditions. 4. We made a new diesel engine that is satisfied design target values(sfc=190 g/hr, NOx + THC=6.0 g/KWh, PM=0.3 KWh), the rate of fuel consumption and emission standard etc., through changing injection timing at the maximum torque point and rated power point. Although we have a little high NOx value.

• Journal of Advanced Marine Engineering and Technology
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• 제19권2호
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• pp.47-55
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• 1995

When the low heavy oil is using as fuel oil to the diesel engine, some problems such as corrosion resistance, wear resistance and heat resistance are happened in diesel engine's internal material, especially the adhesive wear of piston ring groove was occurred as a important problem. Therefore to prevent adhesive wear of its groove, the surface of its groove used to be electroplated with Chrominum and for its Chromium electroplating, Fe anode is being used until nowadays because of its Special shape. However in case of using Fe anode, there were some problems such as deterioation of solution, property of Chromium film, and condition of coation. In this paper Pb anode electroplated withPb to the steel plate was investigated for its Chromium electroplating for Pb's high corrosion resistance in acid solution, and Pb anode is not dissolved compared with Fe anode and deterioration degree of solution in case of Pb anode is smaller than that of Fe anode and also property of Chromium film was better than that of Fe anode. Moreover it was known that the optimum cathodic current density for Pb electroplating to steel plate as insoluable anode for Chromium coating of piston ring groove is 30mA/$cm^2$ by experimental results obtained.

• International Journal of Ocean System Engineering
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• 제3권4호
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• pp.175-187
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• 2013

Moonpools are vertical wells in a floating body used onboard many types of vessels like Exploration and drilling vessels, Production barges, Cable-laying vessels, Rock dumping vessels, Research and offshore support vessels. Moonpool gives passage to underwater activities for different types of ships as per their mission requirements. It is observed that inside a moonpool considerable relative motions may occur, depending on shape, depth of the moonpool and on the frequency range of the waves to which the ship is exposed. The vessel responses are entirely different in zero and non-zero Froude number. Former situation is paid attention in this study as the mission requirement of the platform is to be in the particular location for long period of operation. It is well known that there are two modes of responses depending on the shape of the moonpool viz., piston mode for square shape and sloshing mode for rectangular shapes with different aspect ratios of opening like 1:1.5 and 1:2 ratios. Circular shaped moonpool is also tested for measuring the responses. The vessel moored using heavy lines are modelled and tested in the wave basin. The pretensions of the lines are varied by altering the touchdown points and the dynamic tensions on the lines are measured. The different modes of oscillations of water column are measured using wave gauge and the vessel response at a particular situation is determined. RAOs calculated for various situations provide better insight to the designer.

• Ocean Systems Engineering
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• 제3권2호
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• pp.137-147
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• 2013

Moonpools are vertical wells in a floating body used onboard many types of vessels like cable-laying vessels and offshore support vessels. Moonpool gives passage to underwater activities for different types of ships as per their mission requirements. It is observed that inside a moonpool considerable relative motions may occur, depending on shape, depth of the moonpool and on the frequency range of the waves to which the ship is exposed. The vessel responses are entirely different in zero and non-zero Froude number. Former situation is paid attention in this study as the mission requirement of the platform is to be in the particular location for long period of operation. It is well known that there are two modes of responses depending on the shape of the moonpool viz., piston mode for square shape and sloshing mode for rectangular shapes with different aspect ratios of opening like 1:1.5 and 1:2 ratios. Circular shaped moonpool is also tested for measuring the responses. The vessel moored using heavy lines are modeled and tested in the wave basin. The moored lines are provided with pre-tension and the dynamic tensions on the lines are measured. The different modes of oscillations of water column are measured using wave gauge and the vessel response at a particular situation is determined. RAOs determined for various situations provide better insight to the designer. The experiments done in the wave basin may also be compared with a software package meant for handling moored floating bodies.