• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.222-224
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• 2002

In proton and heavy ion radiotherapy, compensators are required to modify the energy of heavy ion, to compensate the local difference of tumor depth. Conventional compensators have to be created, exchanged, and stored for each patient and for each irradiation directions. A Cylinder Type Liquid Variable Compensator is and is under development. Hexagonal cylinders will be arranged in honeycomb structure. In which air and fluid are divided by hexagonal pistons. The position of each piston will be changed in each cylinder for adjusting the thickness of fluid for variable compensator. The location of each hexagonal piston is determined by each controlling cylinder connected to the hexagonal cylinder by inlet pipes of fluid. Each controlling cylinder includes controlling a piston, which is moved mechanically. Each controlling cylinder is to be moved by a motor driven by a computer.

• 한국자동차공학회논문집
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• 제7권8호
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• pp.17-23
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• 1999

This paper presents the characteristics of the gas flow in the engine cylinder under various intake flow conditins. The particle tracking velovimetry(PTV) was used to anlayze the gas flow pattern and flow field in the cylinder. Effects of tumble intensifying valve(TIV), swirl intensifying valve(SIV) and one-valve deactivated condition on in-cylinder flow patterns were compared with the baseline engine udner 600rpm motoring condition. In addtion, tumbel ration was estimated rwith results of in -cylinder flow fields. Base on experimental results, the tumble ration of in-cylinder flow field has the maximum value at the bottom dead center for the different four inlet conditions. In TIV condition, the tumble ration is 1.35 times larger than that of baseline engine and 1 intake valve deactivated condition is effective to improve in-cylinder swirl motion.

• 센서학회지
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• 제18권3호
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• pp.197-201
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• 2009

This paper studies on the noncontact displacement sensor system to detect the displacement of the cylinder rod. For an inexpensive and a simple process, magnetic scales are printed on the cylinder rod, and magnetized by the specially designed magnetizer that has an yoke through the alternation of N and S pole. Noncontact displacement sensor system consists of cylinder with magnetic scales, Hall sensor, linear guide, controller and display. The system can detect the displacement of moving cylinder with 5 cm/sec in the case of 1 mm magnetic scale. It shows a possibility of position detection of hydraulic cylinder and air cylinder.

• 한국진공학회지
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• 제13권3호
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• pp.132-138
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• 2004

대기압의 공기 중에서 코로나 방전 플라스마에 대한 특성을 연구하기 위해 wire-cylinder 형태의 반응로에서 FCT(flux-corrected transport) 알고리즘과 FEM(finite element method) 방법을 적용한 자체 모순이 없는 1차원 수치적 모델을 사용하였다. 코로나 방전 반응로에 펄스 전압과 직류 전압을 인가하였을 때, 플라스마 밀도의 분포를 계산하여 전압의 변화에 따른 플라스마 특성의 변화를 연구하였으며, 또한 반응로의 크기 변화에 따른 플라스마의 특성 변화를 연구하였다. 이 결과로 얻어지는 활동 반경(active radius)의 변화를 Peek의 실험값과 비교해 보았다. 이와 같은 코로나 방전 플라스마에 대한 수치적 계산 결과는 방전 과정에서 일어나는 물리적 특성을 잘 설명하여 환경오염 물질 제거를 위한 반응로의 최적 설계를 위해 유용하게 쓰일 수 있을 것이다.

• 설비공학논문집
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• 제7권4호
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• pp.556-565
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• 1995

The physical model of interest is based upon the concentric cylinder, where the outside cylinder is filled with optically thick and high temperature phase change material(PCM). The fluid is flowing through the inside cylinder to transfer the appropriate energy. The fluid is flowing through the inside cylinder to transfer the appropriate energy. The governing equations for the phase change material including internal thermal radiation and for the turbulent transfer fluid have been employed and numerically solved. The optically thick phase change justifies the P-l spherical harmonics approximation, which is believed to be appropriate choice particularly for the much coupled problem like in this study. The solid/liquid interface, temperature distribution within the PCM and the heat flux from the PCM to the transfer fluid have been obtained and compared with those of laminar transfer fluid. The numerical results show that the turbulent transfer fluid accelerates the solid/liquid interface and results in the increase of heat transfer rate from the PCM. The internal thermal radiation within the PCM, however, does not always playa role to increase the heat transfer rate throughout the inside cylinder. It is believed that the combined heat flux has been picked up more in the inflowing area than in the pure conductive phase change material.

• 한국자동차공학회논문집
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• 제1권2호
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• pp.27-33
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• 1993

Using the solenoid driven gas injection valve, Hydrogen fuel supply system was made. It was attached to a single cylinder research engine and intake port injection type hydrogen fueled S.I. engine was constructed. Engine performance, emission characteristics, and abnormal combustion were studied through the engine test performed with the variations of fuel-air equivalence ratio and spark timing. Compared with gasoline, hydrogen burns so fast that cylinder peak pressure and temperature are higher and NO is emitted more at full load condition. IN the case of intake port injection type engine, COVimep becomes lower due to the well-mixing of air and fuel, and engine output is lower owing to the low volumetric efficiency. As fuel-air equivalence ratio goes up, the combustion speed increases, and COVimep decreases. NO emission peaks slightly lean of stoichiometric. As spark timing advances and fuel-air equivalence ratio goes up, the cylinder peak pressure and temperature become higher, so abnormal combustions take place easily.

• 대한기계학회논문집
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• 제18권9호
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• pp.2477-2485
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• 1994

Air damper has a great advantage that is independent of temperature change. This paper presents an analysis approach and an application for designing nonviscous air damper with a piston and a cylinder. The objective functions for optimum design is damping coefficient and is maximized by changing two design variables that are length between piston and cylinder and orifice diameter. A digital computer program was developed which determines optimal air damper configuration for maximum damping coefficients. The results were applied to the automatic washer and are confirmed to be valid for the range of operating conditions.

• 대한기계학회논문집B
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• 제24권4호
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• pp.512-518
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• 2000

A wall fuel-film flow model is developed to predict the effect of a wall-fuel-film on air-fuel ratio in an SI engine in transient conditions. Fuel redistribution in the intake port resulting from charge backflow and a simple liquid fuel behavior in the cylinder are included in this model. Liquid fuel film flow is calculated of every crank angle degree using the instantaneous air flow rate. The model is validated by comparing the calculated results and corresponding engine experiment results of a commercial 4 cylinder DOHC engine. The predicted results match well with the experimental results. To maintain the constant air-fuel ratio during transient operation. the fuel injection rate control can be obtained from the simulation result.

• Journal of Advanced Marine Engineering and Technology
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• 제24권4호
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• pp.421-426
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• 2000

A study on the combustion and exhaust emissions characteristics of diesel engine with various suction air humidity is performed experimentally. In this paper, suction air humidity is changed from RH 50% to RH 90%, the experiments are performed at engine speed 1800rpm, and main measured parameters are cylinder pressure, fuel consumption rate, CO, HC, NOx and Soot emissions etc. Increase of suction air humidity from RH 50% to RH 90% does not effect specific fuel consumption, decreases maximum pressure in cylinder, ratio of maximum pressure rise and net heat release, and delays ignition timing. Also, that increases CO and HC emissions, decreases NOx emissions, but does not constant in changing tendency on emission.

• 동력기계공학회지
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• 제12권4호
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• pp.64-71
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• 2008

This study is on pedestrian protection device using pneumatic cylinder and simple link mechanism when vehicle collide with pedestrian. This study ensured the safety space between engine and hood after it applies to simple link mechanism and pneumatic cylinder. It can absorb the damage which measure the specific device if vehicle collide with pedestrian. Combination of simple link mechanism and pneumatic cylinder was more superior than the present pedestrian protection device. Simple link mechanism could confirm superior height and survival probability than when only cylinder operated. It also ensured enough space between engine and hood. And if a cylinder is not working because of old cylinder, poor repair or damage of accident vertical cylinder would be difficult to execute because there exists the irregular space between engine and hood. If simple link mechanism operates with only one cylinder it could ensure the regular space because simple link mechanism set up at the middle of hood. So this device could confirm high safety for pedestrian.