• Elastomers and Composites
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• 제47권4호
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• pp.341-346
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• 2012

사출성형은 고분자성형법 중에서 가장 광범위하게 활용되고 있다. 사출성형은 전형적인 사출성형 외에 가스사출, 물사출, 그리고 사출압축성형 등과 같이 특수한 사출성형방법들이 쓰인다. 사출압축성형은 사출과 압축공정이 합쳐진 것으로 균일한 물성 및 성형의 정밀도를 향상시키기 위하여 사용된다. 또한 사출압축은 잔류응력을 줄이는데도 효과적으로 사용되고 있다. 본 연구에서는 성형품의 형상에 따라 다양하게 나타나는 사출압축성형의 특성에 대해서 컴퓨터 해석을 통해 분석하였다. 성형품에 벽이 있는 제품은 벽의 두께가 압축의 방향과 직각이므로 압축효과가 작게 나타났다. 사출압축성형을 일반사출성형과 비교하였을 때 수축의 균일성 및 수축량 또는 성형수축률이 작게 나타나서 정밀성형에 유리하게 나타났다. 실험계획법을 통해 실제로 제작되고 있는 렌즈에 대해서 최적 사출압축조건을 구하고 이의 결과를 사출성형의 결과와 비교분석하였다.

• 융복합기술연구소 논문집
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• 제1권1호
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• pp.1-4
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• 2011

The object of this experimental study is to investigate the effect on frost prevention and delay by the method of alternating the function of outdoor coil rows under the frost conditions ($2^{\circ}C/1^{\circ}C$). The heat pump system with the new method can make frost delay time longer and eliminate frost effectively. It is withstand over 280 minutes without a conventional defrosting method. Maximum COP in case of adopting new method is 13% higher than that in case of reverse cycle defrosting method. Also in case of moving air injection duct faster, the frost delay time is lengthened and its COP is enhanced more.

• 오토저널
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• 제5권1호
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• pp.89-93
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• 1983

This paper describes on experimental investigation into the heat dissipation of Diesel engine, placing emphasis on the variations of compression ratio and cooling water temperature. The engine used for this test was a vertical single-cylinder four-cycle type, having a direct injection. Engine performance and heat transfer rates was tested under the compression ratio 14.3 and 17.4. In this study, the results showed that output and transfer rates of engine decrease in accordance with the decrease of compression ratio. The effect of cooling water temperature and injection delay of fuel on the heat dissipation brings about the decrease of heat transfer rates from cylinder to cooling water.

• 소성∙가공
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• 제14권5호
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• pp.452-459
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• 2005

Gas assisted injection molding (GAIM) is an innovative low-pressure injection molding technique that can provide numerous benefits such as reduced part warpage, excellent surface quality without sink marks, low injection pressure and greater design flexibility. However, adoptions of GAIM may cause unexpected defects since it requires many subtle design factors such as resin shot size, delay time and gas injection pressure, which wouldn't be considered in conventional injection molding process. Therefore, experiences applying GAIM should be collected and examined in order to establish design rules of the new technique. The purpose of this paper is to summarize developing cases of three automotive interior parts such as instrument panel, map pocket folding and center facia side panel so that possibilities and limitations of GAIM were examined. As a result, it is necessary to consider characteristics of GAIM at the initial stage of part design in order to obtain various advantages of the GAIM process without occurring severe defects, which would increase time and cost required to the part development.

• 대한임상독성학회지
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• 제9권2호
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• pp.101-104
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• 2011

Nicolau syndrome is a rare adverse reaction at the site of an intramuscular injection, and is characterized by severe pain immediately after the injection and rapid development of distinct skin lesions. As this syndrome is rare, it may be overlooked at the early clinical phase and subsequently, clinical outcomes may be worse due to delay in treatment. We report on a female who developed Nicolau syndrome following intramuscular diclofenac injection, which required surgical reconstruction. Understanding the characteristics of Nicolau syndrome and careful surveillance for relevant clinical features may help physicians to more quickly diagnose and treat this condition.

• 한국분무공학회지
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• 제8권3호
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• pp.33-40
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• 2003

The low-emission and high-performance diesel combustion is an important issue in the combustion research community, In order to understand the detailed diesel flame involving the complex physical processes, it is quite desirable to diesel spray dynamics, auto-ignition and spray flame propagation. Dynamics of fuel spray is a crucial element for air-fuel mixture formation, flame stabilization and pollutant formation, In the present study, the diesel RCM (Rapid Compression Machine) and the Electric Control injection system have been designed and developed to investigate the effects of injection pressure, injection timing, and intake air temperature on spray dynamics and diesel combustion processes, In terms of the macroscopic spray combustion characteristics, it is observed that the fuel jet atomization and the droplet breakup processes become much faster by increasing the injection pressure and the spray angle, With increasing the cylinder pressure, there is a tendency that the of spray pattern in the downstream region tends to be spherical due to the increase of air density and the corresponding drag force, Effects of intake temperature and injection pressure on auto-ignition is experimently analysed and discussed in detail.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.447-452
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• 2000

The low-emission and high-performance diesel combustion is an important issue in the combustion research community. In order to understand the detailed diesel flame field involving the complex Physical Processes, It Is quite desirable to study diesel spray dynamics, auto-ignition and spray flame propagation. Dynamics of fuel spray is a crucial element for air-fuel mixture formation flame stabilization and pollutant formation. In the present study, the diesel RCM (Rapid Compression Machine) and the Electric Control injection system have been designed and developed to investigate the effects of injection Pressure, injection timing, and intake air temperature on spray dynamics and diesel combustion processes. In terms of the macroscopic spray combustion characteristics it is observed that the fuel jet atomization and the droplet breakup processes become much faster by increasing the injection pressure and the spray angle. With increasing the cylinder pressure there is a tendency that the shape of spray pattern in the downstream region tends to be spherical due to the increase of air density and the corresponding drag force. Effects of intake temperature and injection pressure on auto-ignition is experimently analysed and discussed in detail.

• 한국자동차공학회논문집
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• 제12권4호
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• pp.24-30
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• 2004

As the environmental pollution becomes serious global problem, the regulation of emission exhausted from automobiles is strengthened. Therefore, it is very important to know how to reduce the NOx and PM simultaneously in diesel engines, which has lot of merits such as high thermal efficiency, low fuel consumption and durability. By this reason, the new concept called as Homogeneous Charge Compression Ignition(HCCI) engines are spotlighted because this concept reduced NOx and P.M. simultaneously. However, there is trade off between output and NOx in a HCCI engine. In this study, output and emission characteristics for a gasoline direct injection type HCCI engine were investigated to clarify the effects of intake air temperature, injection time and mixture formation. From these experiments, we found that the smoke was not produced when the fuel was injected earlier than BTDC 90$^{\circ}$. In addition, the output was increased because of delay of ignition time and NOx emission was decreased because of homogeneous charge of first injection in case of split injection.

• 한국자동차공학회논문집
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• 제14권1호
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• pp.17-24
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• 2006

This study was performed to figure out spray behavior and fuel atomization characteristics of a piezo-driven injector and a solenoid-driven injector in the common-rail injection system under the same design parameters and test conditions. The process of spray injection was visualized by using the spray visualization system composed of a Nd:YAG laser and an ICCD camera. The atomization characteristics were investigated in terms of axial mean velocity, Sauter mean diameter(SMD) and droplet distributions obtained from a phase Doppler particle analyzer system. Compared with solenoid-driven injector, the piezo-driven injector has short injection delay and reaches quickly to the maximum injection value. Spray tip penetration shows some difference, however, spray angle of piezo-driven injector is wider than that of solenoid-driven injector. Sauter mean diameter of piezo-driven type injector is smaller than that of solenoid-driven type.

• 한국분무공학회지
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• 제17권1호
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• pp.1-8
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• 2012

This study described the effect of the multiple injections and diesel-ethanol on the NVH, combustion and emission characteristics of 4 cylinder common rail diesel engine. In order to investigate the influence of diesel-ethanol blended fuel in a light-duty common rail diesel engine, the injection strategy was varied with pilot injection, double pilot injections, and one main injection at various operating conditions. The results showed that diesel-ethanol blended fuel had longer ignition delay than that of the ultra low diesel fuel(ULSD). Also, in the case of multiple injections, the combustion pressure is increased smoothly near the TDC and the NVH are decreased. In the emission characteristics, diesel-ethanol blended fuel produced lower indicated specific nitrogen oxides(IS-NOX) and indicated specific Soot(IS-soot) emissions, however, indicated specific unburned hydrocarbon(IS-HC) and indicated specific carbon monoxide(IS-CO) emissions are slightly increased.