• 소성∙가공
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• 제16권1호
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• pp.54-60
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• 2007

Optimum injection molding condition for a box mold was searched by the Response Surface Analysis(RSA) with the aid of process monitoring system(PMS). Process variables on the control panel of the injection molding machine such as barrel temperatures, screw speed profile, holding pressures, etc. cannot guarantee the uniformity of the material variables directly related with the state of the product in the mold cavity. In order to make sure the state of the resin in the cavity, pressures and temperatures in the cavity, runner and nozzle were monitored in the experiment with the PMS. To accomplish the consistency of the molding process, dependent variables such as the switchover point and holding time were searched with the PMS. With a proper objective function about deflection of the box-type product, the optimum injection molding condition was obtained.

• 대한기계학회논문집
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• 제16권1호
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• pp.77-86
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• 1992

본 연구에서는 사이클은 터빈 출구로 부터 배출되는 폐열을 최대한 회수하여 얻은 증기를 연소기내에 분사시킴으로써 부가적인 압축기 및 비출력의 상향을 기할수 있다.아울러 폐열이용 암모니아 흡수기 냉동기를 구동하여 압축기 입구 온도를 낮 춤에 의해 열효율 및 비출력의 증대는 물론 대기온도 변화에 따른 기관 성능의 변동을 감소시킬 수 있다.

• International Journal of Precision Engineering and Manufacturing
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• 제7권2호
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• pp.8-11
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• 2006

Gas-assisted injection molding (GAIM) process reduces the required injection pressure during mold filling stage as well as the shrinkage and warpage of the part and cycle time. Despite of these advantages, this process needs new parameters and makes the application more difficult because gas and melt interact during the injection molding process. Important GAIM factors involved in this process are gas penetration design, locations of gas injection points, shot size, delay time to inject gas as well as common injection molding parameters. In this study, the experiments are conducted to investigate effects of GAIM process variables on the gas penetration for PP (Polypropylene) and ABS (Acrylonitrile Butadiene Styrene) moldings by changing the gas injection point. Taguchi method is used for the design of the experiments. When the gas is injected at a cavity's center, the most effective factor is the shot size. When the gas is injected at a cavity's end, the most effective factor is the melt temperature. The injection speed is also an effective factor in GAIM process.

• 대한기계학회논문집
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• 제13권1호
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• pp.140-152
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• 1989

본 논문에서는 소형 고속 디젤 분무의 반경 방향의 연류 농도 분포를 고려한 비균질 분무의 분무 선단 도달 거리에 대한 관계식을 유도하고, 비정상 분무인 디젤 분무의 분사 차압-시간 곡선을 입력시킴으로써, 분사 초기 뿐 아니라 전 분사 기간의 분무 선단 도달 거리를 예측할 수 있는 새로운 모델을 제안하여 실험치와 비교 분석하였다. 그리고 분사각과 분열장의 무차원 실험식을 도출하여 계산에 사용하였고 분무 선단 도달 거리의 천이점과 분열장에 대하여 고찰하였다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.333-334
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• 2002

Injection-compression molding parts are many cases with complicated boundary condition which is difficult to analysis of mold characteristics precisely. In this study, the effects of various process parameters such as multi-point gate location, initial charge volume, injection time and pressure have been investigated using finite element method to fomulate the melt front advancement during the mold filling process. A general governing equation for tracking the filling process during injection-compression molding is applied to volume of fluid method. To verify the results of present analysis, they are compared with those of the other paper. The results show a strong effect of processing conditions as a result of variations in the three-dimensional complex geometry model.

• Journal of Oral Medicine and Pain
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• 제42권3호
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• pp.53-61
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• 2017

Myogenous temporomandibular disorder is a collective term for pathologic conditions of the masticatory muscles, mainly characterized by pain and dysfunction associated with various pathophysiological processes. Among the subtypes of myogenous temporomandibular disorder, myofascial pain is one of the most common muscle disorders, characterized by the presence of trigger points (TrPs). Various modalities, such as ultrasound, manipulative therapy, spray-and-stretch technique, transcutaneous electrical nerve stimulation, injection/dry needling, and low-level laser therapy are used to inactivate TrPs. Needling/injection on the TrPs is one of the most common treatments for myofascial pain. Despite the evidence, there is continued controversy over defining the biological and clinical characteristics of TrPs and the efficacy of injection/dry needling. This review discusses the current concept of injection/needling to relieve TrPs.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
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• pp.21-26
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• 1999

Liquefied petroleum gas(LPG) has been used as motor fuel due to its low emissions and low cost. The fuel feeding system has been improved with stringent requirement for exhaust emissions. LPG carburation system was firstly introduced, then the system changed into a gas injection system controlled precisely, but those gas feeding system has a limitation on improving power output. In order to improve an engine performance, a multi-point port injection system was introduced recently, and a liquid direct injection system into a cylinder was suggested as a next generation system to maximize a fuel economy as well as a power. This study addresses the analysis of the LPG spray from diesel injectors. The spray images are visualized and compared with diesel sprays in a wide injection pressure range. The photographs show much wider dispersion of LPG sprays.

• 한국분무공학회지
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• 제8권4호
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• pp.31-38
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• 2003

Constant volume combustion chamber has been designed to investigate diesel spray characteristics with Common-Rail injection system to realize high pressure injection. In this study, two methods of measurements, Schlieren shadowgraphy and Mie scattering imaging method ate applied experimentally to study spray form and liquid phase zone in high pressure, high temperature conditions. Diesel fuel is injected at the point which ignited mixture gas is completely burned. The effect of injection pressure, injector hole diameter, ambient gas temperature and density are investigated experimentally.

• 한국산학기술학회논문지
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• 제14권11호
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• pp.5352-5356
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• 2013

최근 플라스틱 성형품은 기능적인 측면뿐만 아니라 디자인 및 광택과 같이 시각적으로 즉각 식별이 가능한 부분에 까지 많은 관심과 주의를 기울이고 있다. 이와 관련하여 성형품 광택의 제어를 위하여 성형조건이 광택에 미치는 영향에 대한 연구가 필요하지만 관련 연구는 아직 충분히 이루어지지 않고 있다. 따라서 본 연구는 플라스틱 성형품의 외관에 주로 사용되는 ABS (Acrylonitrile-Butadiene-Styrene) 플라스틱 성형품에 대하여 사출압력, 사출속도, 보압력, 수지온도, 금형온도 등의 사출조건의 변화가 성형품의 외관 광택에 미치는 영향에 대하여 사출실험을 통하여 연구하였다. 연구 결과에서 보압력이 가장 큰 영향을 미침을 알 수 있었다. 특히, 보압력 55 - 75MPa 범위에서는 광택도가 증가하지만 그 이상 증가하면 광택이 감소하는데, 그 원인은 SEM(Scanning Electron Microscope)을 통하여 수지 내부의 고무 입자의 변형에 기인한다고 유추할 수 있었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 금형가공 심포지엄
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• pp.125-131
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• 2002

Surface defects in injection molded parts are due to the unsteady flow of polymer melt which are related to the geometries of cavity and gate, the operational conditions of injection and the rheological properties of polymer. In this study we have examined jetting phenomena in injection molding process for three kinds of PCs which have different molecular weight and structure, PBT and PC/ABS alloy with several injection speeds. We have used various cavity shapes that are tensile, flexural and impact test specimens with various gate and cavity thicknesses. Through this study we have observed that the formation of surface defect associated with jetting during filling stage in injection molding is strongly related to die swell. This means that the jetting is strongly affected by the elastic property rather than the viscous property in viscoelastic characteristics of molten polymer. Large die swell would eliminate jetting however, the retardation of die swell would stimulate jetting. In the point of mold design, reducing the thickness ratio of cavity to gate can reduce or eliminate jetting and associated surface defects regardless of magnitude of elastic property. It also enlarges process window that can produce steady flow of polymer melt in injection molding.