• 동력기계공학회지
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• 제6권2호
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• pp.54-59
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• 2002

The principle of the FDM(fused deposition modeling) process is based on the layer by layer manufacturing technology, like other RP(rapid prototyping) process. In the FDM process, each layer may have different shape. Therefore, the built model may have stairs shape on its surface. This stairs shape is one of the serious problems in the FDM process. Thus in this study, cube models and spherical models were fabricated by FDM process to investigate the influence of injection amount on surface roughness. Models with various road width were also built to investigate the influence of road width on surface roughness. Surface roughness of the models was measured and analyzed. The result obtained in this study are expected to help selecting the part build orientation for optimum surface roughness.

• 한국분무공학회지
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• 제5권3호
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• pp.9-16
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• 2000

In a SI engine, three-way catalyst converter has the best efficiency when A/F ratio is near the stoichiometry. The feedback control using oxygen sensors in the commercial engine has limits caused by the system delays. So it is necessary to control fuel quantity in accordance with intake air amount in order to reduce exhaust emission and improve the specific fuel consumption. Precise A/F ratio control requires measurement of air amount with respect to the cylinder and injection fuel according to the air amount In this paper, we applied nonlinear fuel injection model and developed the algorithm of A/F ratio control. This algorithm includes the methods of measurement of transient air mass flowing into each cylinder, of calculation of injection pulse width for measured air mass, and the method of feedback and engine control by using lambda sensor. Also we developed control program for IBM-PC by using C++ Builder, and tested it in the commercial engine.

• 한국자동차공학회논문집
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• 제6권1호
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• pp.27-35
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• 1998

This study describes the influence of combustion parameters on the nitric oxide emission, such as injection timing, air flow rate, injected amount of fuel, and compression ratio of engine. In order to determine the influence factors on the nitric oxide emission, the experiment were investigated with various parameters of engine cycle. According to the results of this study, the retardation of injection timing and the increases of airflow rate, and the decreases of fuel injection amount reduce the nitric oxide concentration in the exhaust emissions. Also, the increases of compression ration of engine increase in the concentration of nitric oxide formation in the combustion chamber. The results of this study give a guideline to decrease the nitric oxide formation by using the simulation program.

• 한국자동차공학회논문집
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• 제17권4호
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• pp.79-85
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• 2009

Low temperature combustion regime for the simultaneous reduction of nitrogen oxides ($NO_x$) and paticulate matter (PM) is demonstrated in single cylinder engine at various operating parameters, such as EGR rate, injection timing, EGR temperature, amount of fuel and swirl rate. Low temperature combustion is accomplished by high exhaust gas recirculation (EGR) rate in this study. Generally, the emission of $NO_x$ almost completely disappears and PM significantly increases in the first decreasing regime of oxygen concentration but after peaking about 10~12% oxygen concentration, PM then decreases regardless of fuel injection quantity. Low temperature combustion regime was extended by low EGR temperature, high injection pressure and low amount of fuel.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1114-1119
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• 2004

In a foaming process of microcellular plastics (MCPs) with a injection molding, research on the viscosity change that occurs when the gas is injected to the polymer has received little attention despite its importance. The purpose of this paper is to provide the basic data required to determine the processing condition by measuring viscosity changes against the gas injection rates of the blowing agent, and to verify the influence of the viscosity change on the flow condition of polymer inside the mold at the injection process.

• 한국가스학회지
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• 제22권5호
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• pp.18-23
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• 2018

본 연구에서는 CNG자동차 인젝터의 외부 환경온도에 따른 인젝터의 분사량을 분석하고자 한다. 특히 냉간 시동시와 같은 조건에서 분사량의 변화를 측정하여 저온환경이 가스인젝터 성능에 미치는 영향을 파악하고자 하며, 가스 인젝터 내부의 스프링 특성을 다르게 하여 실험을 진행 하였다. 실험 장치는 연료 공급부, 유량 측정부, 온도 챔버와 인젝터 제어부로 구성하였다. 실험결과를 통해 저온환경일수록 가스인젝터의 초기 분사량이 증가하였으며, 스프링길이 증가에 따른 니들의 열리는 시간(무효분사시간)이 지연됨을 확인하였다.

• 한국환경보건학회지
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• 제8권1호
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• pp.55-60
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• 1982

This study was carried out in order to clarify the combined effect of cadmium and lead on rat bones when exposed to single metal (1 mg cd/kg body weight) and cambined metals (1 mg cd + 4 mg pb/kg body weight). Seventy five mature rats of Sprague-Dawley species were divided into a control group and a treatment group that were administered by daily peritoneum injection for 7 to 9 weeds, and their body weights were measured every week. The results were summarized as follows 1. Body weight gains of the combined injection group and the single injection groups were lower than that of the control group. 2. In case of the combined injection group, the amount of cadmium accumulated in femur was more than that of the cadmium group. These amounts of cadmium accumulated showed an increasing trend. 3. The lead amount in bone tissue of the combined injection group presented also an increasing trend. In this case, the additive action of cadmium to the lead accumulation in bone tissue was conspicuous. 4. The amounts of calcium and phosphorus in femur showed clear a decreasing trend in the cadmium group and combined administration group. The ratio of calcium and phosphorus (ca/p) in the cadmium group was not different from that of the control group, but in the combined injection group the ratio was a little lower.

• 수도
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• 제24권1호통권82호
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• pp.55-56
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• 1997

• 한국분무공학회지
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• 제23권1호
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• pp.36-41
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• 2018

Fuel wall film effects power output and cycle deviation by changing the amount of fuel flowing into cylinder in PFI gasoline engines. Reduction of wall film can reduce fuel consumption and improve combustion stability. In this research, the effects of injection strategies including injection pressure and dual injection system is investigated for reducing wall film formation. The CONVERGE software is used for numerical analysis tool and O'Rourke film splash model was used for wall film prediction model. Compared with the reference case wall film decreased with increase of injection pressures, and the film formation reduced when the dual injection system was used.

• 한국자동차공학회논문집
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• 제21권5호
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• pp.15-24
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• 2013

Numerical studies were conducted to investigate the internal flow field and combustion characteristics of DISI engine with methanol blended in gasoline. Dual injection was applied and the characteristics were compared to single injection strategy. The amount of the fuel injection was corresponded to air-fuel ratio of each fuel for complete combustion. The preforming model in this study, software STAR-CD was employed for both modeling and solving. The operating speed condition were at 4000 rpm/WOT (Wide open throttle) where the engine was fully warmed. The results of single injection with M28 showed that the uniformity, equivalence ratio, in-cylinder pressure and temperature increased comparing to gasoline (M0). When dual injection was applied, there was no significant change in uniformity and equivalence ratio but the in-cylinder pressure and temperature increased. When M28 fuel and single injection was applied, the CO (Carbon monoxide) and NO (Nitrogen oxides) emission inside the combustion chamber increased approximately 36%, 9% comparing with benchmarking case in cylinder prior to TWC (Three Way Catalytic converter). When dual stage injection was applied, both CO and NO emission amount increased.