• 대한기계학회논문집B
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• 제28권10호
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• pp.1172-1177
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• 2004

The emission control of automobile has been intensified as a part of the countermeasure to decrease air pollution in the world. As the cars with an alternative fuel starts to get into the spotlight, the cars with low emission has been introduced and exhaust gas regulation forced in this country. These days, LPG vehicles, which infrastructure of fuel was already built up, and CNG vehicles are recognized for alternative fuel cars in this country. In this study, the constant volume combustion chamber was manufactured and used for experiments to obtain the combustion characteristics of propane mixture. The combustion characteristics was analyzed, with the change of supply conditions of propane fuel. Inside the combustion chamber, the maximum temperature increase with the initial pressure is going up. The burning velocity also seems to have the same characteristic as the temperature. However, the heat flux do not change much according to the theoretical correct mixture but it changes with the various initial temperature of the combustion chamber.

• 대한기계학회논문집B
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• 제29권2호
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• pp.180-188
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• 2005

It is well known that a lean burn engine caused by stratified mixture formation has many kinds of advantages to combustion characteristics, such as higher thermal efficiency and lower CO, NOx levels than conventional homogeneous mixture combustion. Although this combustion can achieve low fuel consumption technology, it produces much unburned hydrocarbon and soot because of heterogeneous equivalence ratio in the combustion chamber. Therefore, the stratified mixture formation technology is very important to obtain the stable lean combustion. In this paper, fundamental studies for stratified combustion were carried out using a constant volume combustion chamber. The local effect of mixture formation according to control air-fuel distribution in the chamber was examined experimentally. In addition, the effect of turbulence on stratified charge combustion process was observed by schlieren photography. From this study, we found that the flame propagation speed increase with swirl flow and the swirl promotes the formation of fuel and air mixture.

• International Journal of Automotive Technology
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• 제6권4호
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• pp.305-314
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• 2005

Injection rate shape control is one feature of a diesel fuel injection system that is strongly desired at this time. In the conventional common rail system, it is difficult to control the injection rate since the fuel pressure is constant during the injection period, resulting in a nearly rectangular rate shape. In order to look into possible injection modulations, injectors equipped with standard and geometrically modified control valves were investigated in detail by means of computer modelling and simulation. Experiments were carried out to validate the feasibility of such a shaping. The results of this study show a noteworthy dependence of the fuel rate on geometrical modifications in the piloting stage of the injector.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.170.1-170
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• 2001

This paper developed the model for electro hydraulic force control system by identification method via ARMAX model. Implementation of Identification is performed on Pin-On-Disk type tribotester. The wear mechanism is an important mechanic property to select a material´s life and a optimum work condition. Pin-on-disk type tribotester is popular wear analysis experimental equipment and its mechanism is that adding a force on a rotating disk to simplify two surface contact´s wear experimental condition. Material´s rotating velocity and eccentricity rotation makes disturbance and it affects adding constant force. To get a high performance of force adding part, DDV(Direct Drive Valve) which has pressure control loop is used. To obtain a tribotester´ s ARMAX model, prediction error method(PEM) is used in case force adding part and rotating part is ...

• Bulletin of the Korean Chemical Society
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• 제27권9호
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• pp.1429-1432
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• 2006

Polyaromatic hydrocarbons were separated by a capillary supercritical fluid chromatographic (SFC) column and detected by a UV detector at the wavelength of 280 $\mu$m. The temperature-controlled restrictor was designed for UV detection. The temperature-controlled restrictor is a 20 cm length of deactivated fused silica of 7 mm i.d. which is held right after UV detector of the capillary SFC. The temperature of the restrictor will control the flow rate of the supercritical carbon dioxide mobile phase through the capillary column in SFC. Thus as the pressure in the column is increased from 1500 psi to 4000 psi during a pressure program, the temperature of 7 $\mu$m fused-silica tube can be varied from 100 to 350 ${^{\circ}C}$ to maintain a constant flow rate.

• International Journal of Air-Conditioning and Refrigeration
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• 제9권2호
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• pp.51-61
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• 2001

A numerical study has been conducted to characterize the transient pressure in a simple water supply pipe system with an air chamber by utilizing a commercial code that employs the method of characteristics. Some results produced for validation in the study agree quite well with the previously reported. Several parameters are than varied. Among them are the valve closure time, the wave speed, the static pressure, the polytropic exponent, the air chamber volume, the diameter and the shape of orifice in the air chamber, etc, while the water temperature and velocity are kept constant at $20^\circ{C}$ and 0.8m/s, respectively. Results reported in this parametric study may be useful to understand the unsteady behavior of the system.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.245-250
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• 2003

In order to control indoor air quality and save energy, it is needed to install a suitable ventilation system equipped with heat exchanger for heat recovery. The purpose of this research is to find the performance of paper heat exchanger for exhaust heat recovery, which exchanges latent heat as well as sensible heat. Experimental apparatus comprises heat exchanger model, constant temperature and humidity chamber, fan and measurement systems for temperature, pressure and flow rate. Thermal performance and pressure loss of the paper heat exchanger are measured and compared at various air velocities and outdoor conditions. Experimental results show that paper heat exchanger can recover $50{\sim}70%$ of the enthalpy difference between supply and exhaust air.

• 한국추진공학회지
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• 제18권5호
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• pp.19-28
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• 2014

핀틀 노즐 기술을 적용한 고체 추진기관의 지상 연소시험을 수행하여 내탄도 성능 해석과 비교하였다. Baffle이 없는 핀틀-노즐 추진기관 시험 결과 초기 압력은 내탄도 성능 해석 결과와 유사하였으나 점진적으로 압력이 증가하는 현상이 나타났다. 또한, 핀틀 주변으로 공급되는 유동을 균일하게 형성하기 위하여 baffle을 추가하여 시험을 수행하였다. 시험 결과 예측되는 압력보다 40% 높은 압력이 측정되었으며 CFD 유동해석을 통하여 baffle에 의한 전압력 손실이 발생하며 10%의 전압력 손실을 고려하여 예측된 연소실 압력이 측정 압력과 유사함을 확인하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제30권3호
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• pp.351-358
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• 2006

The capability of high pressure injection with small fuel quantify at all engine operating conditions is one of the main feature in common rail fuel injection system, which is used in small and light-duty Diesel engine. The key parameter for the better atomized fuel sprays and multiple injections of this common rail fuel injection control, that can be freely selected irrespective of the engine speed and load is the mechanism controlling the needle energizing and movement in high pressure Diesel injector. In the electro-hydraulic injector, the injection nozzle is being opened and closed by movement of the injector's needle which is balanced by pressure between the nozzle seat and the needle control chamber. This study describes the macroscopic spray structure characteristics of the common rail Diesel injectors with different electric driving method i.e. the solenoid-driven and piezo-driven type. The macroscopic spray characteristics such as spray tip speed. spray tip penetration and spray cone angle were investigated by the high speed spray, which is measured by the back diffusion light illumination method with optical system for the high speed temporal photography in a constant volume chamber pressurized by nitrogen gas. As the results, the prototype piezo-driven injector system was designed and fabricated for the first time in domestic case and the effect of injector's needle response driven by different drive type was compared between the solenoid and piezo-driven injector It was found therefore. that the piezo-driven injector showed faster needle response and had better needle control capability by altering the electric input value than the solenoid-driven injector.

• Journal of Chest Surgery
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• 제31권9호
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• pp.845-854
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• 1998

Background: S-2-(3 aminoprophlamino) ethylphosphorothioic acid(WR-2721) is one of the radical scavenging thiols. We tested its protective effects in the reperfused heart. Material and Method: The experimental setup was the constant pressure Langendorffs perfusion system. We investigated the radical scavenging properties of this compound in isolated rat hearts which were exposed to 20 minutes ischemia and 20 minutes reperfusion. Four experimental groups were used:group I, control, Amifostine 50 mg(1 mL) peritoneal injection 30 minutes before ischemia(group II), Amifostine 10 mg(0.2 mL) injection during ischemia through coronary artery(group III),and Amifostine 50 mg(1 mL) peritoneal injection 2 hrs before ischemia(group IV). The experimental parameters were the levels of latate, CK-MB, and adenosine deaminase(ADA) in frozen myocardium, the quantity of coronary flow,and left ventricular developed pressure, and it's dp/dt. Statistical analysis was performed using repeated measured analysis of variance and student t-test. Result: The coronary flow of group II and IV were less than group I and III at equilibrium state but recovery of coronary flow at reperfusion state of group II, III, and IV were more increased compared with group I. The change of systolic left ventricular devoloping pressure of group II and IV were less than control group at equilibrium state, which seemed to be the influence of the pharmacological hypotensive effect of amifostine. But it was higher compared with group I at reperfusion state. The lactic acid contents of group II were less than control group in frozen myocardium.(Group I was 0.20 0.29 mM/g vs Group II, which was 0.10 0.11 mM/g). The quantity of CK-MB in myocardial tissue was highest in group IV (P=0.026 I: 120.0 97.8 U/L vs IV: 242.2 79.15 U/L). The adenosine deaminase contents in the coronary flow and frozen myocardium were not significantly different among each group. Conclusion: Amifostine seemed to have significant cardioprotective effect during ischemia and reperfusion injuries of myocardium.