• 오토저널
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• 제15권3호
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• pp.55-67
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• 1993

In this study, the thermal behavior characteristics of the cylinder block of a small 3-cylinder, 4-stroke gasoline engine were analyzed, using the 3-dimensional finite element method. Before numerical analyses were conducted, the performance test and the heat transfer experiment of the engine were carried out in order to prepare the input data for the computations. Engine cycle simulation was performed to obtain the heat transfer coefficient and the temperature of the gas and the mean heat transfer coefficient of coolant. Temperature fields as a result of steady-state heat transfer were obtained and compared with experimental results measured at specific points of the inner and the outer walls of the cylinder block. The thermal stress and deformation characteristics resulting from the nonuniform temperature distributions of the block were investigated. The effects of the thermal behaviors of the cylinder block on the engine operations and the unfavourable aspects of excessive thermal loading were examined on the basis of the calculated results.

• 오토저널
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• 제13권6호
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• pp.57-64
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• 1991

Spart-ignition engine knock is an abnormal combustion phenomenon originated from auto- ignition of a portion of or the entire end-gas during the later stage of combustion process. And engine knock is accompanied by a vibration of engine cylinder block and a high-pitched metallic noise. Engine knock is characterized in terms of its intensity, its occurrence crank angel and the percentage of engine knock cycles. To characterize engine knock, a precise measurements of cylinder pressure and a statistical analysis of cylinder pressure data are needed. The purpose of this study is to develope a technique to measure engine knock and its characteristics as a function of ignition timing change. A 4-cylinder spark-ignition engine and unleaded gasoline, whose octane number was 94, were used for experiments. To measure engine knock and to analyze engine knock characteristics, cylinder pressure data were sampled by a high speed data acquisition system which was developed in this study. Cylinder pressure data were sampled at each 0.1.deg. crank angle and the number of cycles continuously sampled was 80.

• Journal of Advanced Marine Engineering and Technology
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• 제28권1호
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• pp.75-82
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• 2004

In this research, a computer analysis has been developed for predicting the Pipe pressure of the intake and exhaust manifold in a small single cylinder engine. To get the boundary conditions for a numerical analysis one dimensional and unsteady gas dynamic calculation is performed by using the MOC(Method Of Characteristics). The main numerical parameters are engine revolutions. to calculate the Pulsating flow which the intake and exhaust valves are working. The distributions of the exhaust pipe pressures were influenced strongly to the cylinder pressures and the shapes of exhaust pressure variation were similar to the Inside of cylinder pressure As the engine revolutions are increased. the intake pressure was lower than ambient pressure. The amplitude of exhaust pressure had increased and the phase of cylinder pressure $P_c$ is delayed and the amplitude of cylinder pressure were increased.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.799-803
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• 2008

The possibility of manufacturing titanium hollow cylinder tank for ramjet engine was demonstrated with superplastic forming of subscale article. An innovative manufacturing method to produce complex configuration from titanium multi-sheets by low hydrostatic pressure was presented. Finite element analysis on superplastic blow forming process has been carried out in order to improve the forming process when manufacturing subscale hollow cylinder structure using Ti-6Al-4V multi-sheets. The simulation focused on the reduction of forming time and obtaining finally required shape throughout investigating the deformation mode of sheet according to the forming conditions and die geometry. From pre-sized titanium sheets, near net shape of hollow cylinder tank is obtained by superplastic blow forming conducted using gas pressure of 15bar at 1148K. The result shows that the manufacturing method with superplastic forming of multi-sheets of titanium alloy has been successful for near net shape forming of subscale hollow cylinder tank of ramjet engine.

• 한국가스학회지
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• 제25권5호
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• pp.19-29
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• 2021

기후변화에 대응하기 위해 세계적으로 이산화탄소 및 대기오염 물질 배출 규제가 점차 강화됨에 따라 내연 기관 자동차를 친환경 자동차로 전환하려는 추세이다. 이는 정부의 수소 에너지 활성화 정책에 따른 충전 인프라 구축, 충전 설비 핵심 부품의 국산화 지원으로 가속화되고 있다. 본 연구에서는 유한 요소 해석을 통해 수소 연료 전지 자동차 용기 밸브의 과류 방지 장치를 설계하고, 시험을 통해 성능을 평가하였다. 주요 시험 항목인 정수압, 연속 작동, 압력 임펄스, 누설, 작동 시험을 ISO 12619-2, ISO 12619-11의 시험 방법에 따라 수행한 결과 요구 조건을 만족함을 확인하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제28권7호
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• pp.1101-1110
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• 2004

An one-zone heat release analysis was applied to a 4 cylinder indirect injection diesel engine. The objective of the study is to calculate heat release accurately considering the effect of specific heat ratio. heat transfer and crevice model and to find out combustion characteristics of an indirect diesel engine considering the effect of the pressures in main and swirl chambers. Especially specific heat ratio indicating combustion characteristics is adapted. instead of that indicating matter properties, which has been used in former studies Moreover by adaption of blowby model, cylinder gas mass became accurately calculated. Therefore, with ideal gas equation, calculating cylinder gas temperature, it was found to affect heat transfer loss and heat release. Determining heat transfer constants $C_1$. $C_2$ as 0.6 respectively. the integrated gross heat release values were predicted well for the measured value at various engine speed, full load operating conditions. The curve of heat release rate was similar to SI engine rather than DI engine. That is originated from that swirl chamber reduce an instant combustion which occurs in DI engine due to ignition delay on early stage of combustion.

• 한국분무공학회지
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• 제15권3호
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• pp.131-139
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• 2010

Gas motion within the engine cylinder is one of the major factors controlling the fuel-air mixing and combustion processes in diesel engines. In this paper, a special swirl-chamber is designed and applied to a DI (direct injection) diesel engine to generate a strong swirl motion thus enhancing gas motion. Compression, combustion and expansion strokes of this DI diesel engine with the swirl-chamber have been simulated by CFD software. The simulation model was first validated through comparisons with experimental data and then applied to do the simulation of the spray and combustion process. The velocity and temperature field inside the cylinder showed the influences of the strong swirl motion to spray and combustion process in detail. Cylinder pressure, average temperature, heat release rate, total amount of heat release, indicated thermal efficiency, indicated fuel consumption rate and emissions of this DI diesel engine with swirl-chamber have been compared with that of the DI diesel engine with $\omega$-chamber. The conclusions show that the engine with swirlchamber has the characteristics of fast mixture formulation and quick diffusive combustion; its soot emission is 3 times less than that of a $\omega$-chamber engine; its NO emission is 3 times more than that of $\omega$-chamber engine. The results show that the DI diesel engine with the swirl-chamber has the potential to reduce emissions.

• 한국가스학회지
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• 제11권2호통권35호
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• pp.37-42
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• 2007

본 논문에서는 밸브몸체와 밸브스템 사이의 사각그루브에 설치한 두 개의 O-링에 대한 누설 안전성을 해석한 결과를 제시하고 있다. O-링시일의 누설 안전성에 대한 해석은 압축률과 LPG 가스압력의 변동에 따라 발생되는 누설 안전성을 유한요소해석 프로그램 MARC로 계산하였다. FEM 해석결과에 따르면, LP가스 충전압력 $8kg/cm^2$에서 안전변의 안전한 작동압력 상한치 $24.8kg/cm^2$에 이르기까지 압력하중을 압력용기 안전기준에 의거 계산한 결과는 안전한 것으로 나타났다. 다만, 두 개의 O-링의 안전성을 충분하게 확보하기 위해서는 O-링소재의 시효경화 효과를 고려하는 것이 바람직하다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.119-124
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• 2008

Recently, focus has been drawn on natural refrigerants due to increasing concern on global warming. As a consequence, CO2 systems such as a heat pump water heater using CO2 as a refrigerant are rapidly growing on the market. Currently, rolling piston rotary compressors are widely used for CO2 heating and/or refrigeration systems. There are several ways of realizing gas compression structure. They are single stage compression with single cylinder, single stage compression with two cylinders, and two stage compression with two cylinders. In this paper, computer simulation program which was validated for a single stage rotary compressor with one cylinder has been extended for a single stage, two cylinder rotary type. Numerical investigation has been made on optimal design for the cylinder configuration using the extended simulation program. For a single stage two cylinder rotary compressor having a displacement volume of 4 cc for each cylinder, compressor efficiency has been found to be maximum when the cylinder radius and height are 31mm and 10mm, respectively.

• 한국유체기계학회 논문집
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• 제19권3호
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• pp.53-56
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• 2016

In this study, experiments and finite element method analysis were used to determine the autofrettage pressure that is optimal and then maximizes the cycling life of Type3 composite cylinders used in self-contained breathing apparatus. For both approaches, the cylinders were pressurized at 100, 110, ${\ldots}$, 290 % of the test pressure, respectively. The stresses were computed by the FEM analysis; while the strains of cylinders were recorded and the failure modes were monitored during the cycling test. As a result, from the good agreements between the simulations and experiments, it was concluded that at least 70 % of the test pressure should be applied as the autofrettage pressure in order to takes visible effect on the cycling life, and 160 % of the test pressure induces the maximum cycling life and the desired failure mode.