• 한국정밀공학회지
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• 제22권12호
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• pp.100-107
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• 2005

The present work covers a new ray tracing scheme of an injection-molded plastic lens linked with finite element analysis fur injection molding processes. The traditional ray tracing schemes have been based on the assumption that optical property of the lens is homogeneous throughout the entire volume. However, this assumption is quite unrealistic for injection-molded plastic lenses since material properties vary at every point due to injection molding effects. In order to consider non-homogeneous property of a lens, a modified ray tracing method is proposed in connection with finite element analysis of injection molding. Through the analysis of the injection molding process, the distribution of refractive indices can be obtained. This information is then utilized in the proposed ray tracing scheme based on finite element meshes so as to take into account variation of the refractive indices. The effect of mold temperature is also investigated through finite element analysis, and the relevant optical quality is evaluated through the proposed ray tracing simulation.

• 대한치과보철학회지
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• 제33권1호
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• pp.13-23
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• 1995

The purpose of this study is to inquire about the effects of individual tray design and impression method on the border extension and contour of denture. 10 students at the dentistry college who have normal occlusion and symmetric facial form and normal facial muscle activity were selected. The tray was designed three types (large, medium, small tray). After border molding was done by dentist and operator, final impression was taken. The length of impression body and width of border were measured by a vernier caliper on the cast. The obtained results were as follows : 1. As the tray border was shortened, the length of impression body and width of border was short (P<0.01). 2. When the impression was taken with the small tray, the length of impression body was short in passive border molding than active border molding. 3. When the medium tray was used, the width of impression body was short in passive border molding than active border molding.

• 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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.1135-1138
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• 2003

The transformer is major equipment in power receiving and substation facilities. Necessary conditions required for the transformer are compactness, lightness, high reliability, economic advantages, and easy maintenance. The pole-mount transformer installed in distribution system is acting direct role in supply of electric power and it is electric power device should drive for long term. Most of modem transformer are oil-filled transformer and accident is happening considerable. The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and low loss. One body molding transformer needs some cooling method because heat radiation between each winding is difficult. In this paper, The thermal analysis of pole mount mold transformer with one body molding by duct condition is investigated and the test result of temperature rise is compared with simulation data.

• Design & Manufacturing
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• 제17권2호
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• pp.62-69
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• 2023

In this study, we conducted a study on the optimization of injection molding conditions to minimize deformation of plastic product. The charging management system housing of the vehicle was selected as the research subject. Melting temperature, cooling temperature, packing time, and packing pressure were selected as the main factors expected to affect the deformation of molded products. Each main factor was divided into 5 levels. Optimization of injection molding conditions to minimize deformation was performed using the Taguchi Method. We performed an analysis of variance (ANOVA) to identify significant factors affecting the deformation of plastic product. In order to select injection molding conditions that minimize deformation of plastic products, injection molding analysis was additionally performed for insignificant factors. We then compared the deformation of the molded part before and after optimization. As a result of comparing the injection analysis results of the basic conditions and the injection analysis results of the optimal conditions, it was confirmed that the amount of deformation after optimization was improved by about 10.9%.

• 대한기계학회논문집A
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• 제21권11호
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• pp.1773-1785
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• 1997

The cooling stage is the very critical and most time consuming stage of the injection molding process, thus it cleary affects both the productivity and the part quality. Even through there are several commercialized package programs available in the injection molding industry to analyze the cooling performance of the injection molding coling stage, optimization of the cooling system has npt yet been accomplished in the literature due to the difficulty in the sensitivity analysis. However, it would be greatly desirable for the mold cooling system designers to have a computer aided design system for the cooling stage. With this in mind, the present study has successfully developed an interated computer aided design system for the injection molding cooling system. The CAD system utilizes the sensitivity analysis via a Boundary Element Method, which we recently developed, and the well-known CONMIN alforuthm as an optimization technique to minimize a weighted combination (objective function) of the temperature non-uniformity over the part surface and the cooling time related to the productivity with side constranits for the design reality. In the proposed objective function , the weighting parameter between the temperature non-uniiformity abd the cooling time can be adjusted according to user's interest. In this cooling system optimization, various design variable are considered as follows : (i) (design variables related to processing conditions) inlet coolant bulk temperature and volumetric flow rate of each cooling channel, and (ii) (design variables related to mold cooling system design) radius and location of each cooling channel. For this optimum design problem, three different radius and location of each cooling channel. For this optimum design problem, three different strategies are suffested based upon the nature of design variables. Three sample problems were successfully solved to demonstrated the efficiency and the usefulness of the CAD system.

• 한국전산유체공학회지
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• 제18권3호
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• pp.20-25
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• 2013

In various manufacturing industries, an in-mold decoration (IMD) process for plastic objects is widely utilized because a film forming and an injection molding processes run simultaneously. In the present study, the deformation of polymer film and filling of resin in the IMD process were numerically investigated to evaluate the quality of the plastic object formed by the IMD process, which consists of thermoforming and injection molding processes. To obtain the initial shape of the polymer film during the injection molding process, the deformation of the polymer film in the thermoforming process was pre-formed using the vacuum conditions to attach the film to a cavity. Since the properties and deformation of polymer film are greatly affected by the behavior of polymer resin being injected into a mold cavity, numerical simulations for the injection molding and film forming were performed with one-way coupling method. The results showed that the injected resin could lead to the tearing of the polymer film in local regions near the corners. In order to verify the proposed numerical methodology, the numerical results of the deformation patterns printed on the initial polymer film were compared with the experimental data. The proposed methodology to couple film forming analysis with injection molding analysis can be used to predict the deformation of film in IMD process.

• 폴리머
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• 제38권6호
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• pp.708-713
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• 2014

대부분의 플라스틱 제품은 사출성형을 통해 생산된다. 사출성형에서 성형수축은 피할 수 없으며 이는 제품에 휨이나 뒤틀림을 유발하여 제품의 치수정밀도를 떨어뜨리는 요인으로 작용한다. 사출성형 시 발생하는 휨이나 뒤틀림은 성형조건이나 제품의 형상에도 영향을 받지만 수지의 물성에 따라서도 다양하게 나타난다. 본 연구에서는 제품의 휨을 제어하기 위해 폴리카보네이트를 유리섬유로 보강하여 물성을 예측하였으며, 이를 이용하여 사출성형해석을 실시하였다. 사출성형해석을 통해 유리섬유로 보강된 수지에서 제품의 휨이 감소하는 것을 확인할 수 있었다. 본 연구방법의 타당성과 신뢰성을 검증하기 위하여 사출실험을 실시하여 수지의 물성에 따른 휨 값을 분석하였으며 해석과 실험에서 유사한 경향의 휨이 발생하는 것을 관찰할 수 있었다. 결론적으로 본 연구에서 수행한 바와 같이 해석 프로그램을 통해 수지의 물성을 설계하고 이를 통한 휨의 제어가 가능함을 확인할 수 있었다.

• Transactions on Electrical and Electronic Materials
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• 제9권6호
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• pp.237-242
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• 2008

The effects of the process parameters in the molding of aspheric glass lenses for camera phone modules have been investigated experimentally. The molding conditions were optimized with respect to the form accuracy (PV) (the response variable) of the molded lens. The experimental conditions were obtained by employing a factorial design method. From the analysis of variance (ANOVA) and P-value (significance level), the slow cooling rate was found to affect the response variable most significantly. The lens molded under the optimum molding condition showed a transcription ratio of 93.4%.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 The Korea-Japan Plastics Processing Joint Seminar
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• pp.27-32
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• 2003

The wavelike flow mark phenomenon is one of the surface defects that can arise during the injection stage of the injection molding process. We have performed a numerical analysis using a finite element method for the injection molding to verify the validity of 'Go-over' hypothesis. Also, we have compared the results of numerical analysis with available experimental data. Numerical analysis results of the flow marks are qualitatively in good agreement with experimental data of reference, but are quantitatively deviated from experimental data in a consistent manner. A parametric study has been performed to examine the correlative effects of various injection molding processing parameters and material properties on the flow mark size.