• Composites Research
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• v.31 no.1
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• pp.12-16
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• 2018

Composite material and mold steel can be expanded differently with the temperature gradients during the forming process because their coefficients of thermal expansions are not the same. Therefore, in order to manufacture the product with accuracy, it is necessary to verify that the forming pressure on the surface of the composite material is maintained to the required level from the material supplier. In this paper, the pressure between the composite material and mold due to the temperature difference was predicted by finite element analysis and the accuracy of predicted value was verified by measuring the thermal expansions of mold steel by the ruler. The predicted value by finite element analysis is closely in agreement with one by the experiment within the required tolerance value of ${\pm}0.05mm$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.3
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• pp.348-352
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• 2004

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 ow loss, but it needs some cooling method because heat radiation between each winding is difficult. The life of transformer is significantly dependent on the thermal behavior in windings. Many transformer designers have calculated temperature distribution and hot spot point by finite element method(FEM) to analyze winding temperature rise. 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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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.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.12
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• pp.8-15
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• 2021

Cold forging is a method in which molding is performed at room temperature. It has a high material recovery rate and dimensional precision and produces excellent surface quality, and it is mainly used for the production of bolted or housing products. The lifespan of cold forging molds is generally determined by the wear of the mold, plastic deformation of the mold, and fatigue strength. Cold forging molds are frequently damaged due to fatigue destruction rather than wear and plastic deformation in a high-temperature environment as it is molded at room temperature without preheating the raw material and mold. Based on the results analyzed through FEM, an effective mold structure design method was proposed by analyzing the changes in tensile and compressive stresses on molds according to the number of molds and reinforcement rings and comparing the product geometry and mold stress using three existing mold models.

• Design & Manufacturing
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• v.9 no.3
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• pp.9-13
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• 2015

Plastic material has been applied to many automobile parts with the automotive lightweighting trend. In this study, a passenger air bag(PAB) housing which is produced by steel material in the present were molded using a plastics material. Before design and making of a mold for the PAB housing molding, it was carried out injection molding analysis. By analyzing the deformation results, the correction dimension for mold designing was determined. The design and manufacturing the mold applied the correction dimension were conducted. It was performed actual injection molding. The warpage value of the PAB housing was similar to the warpage of the injection molding analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.6
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• pp.481-487
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• 2008

Rapid mold heating has been recent issue to enable the injection molding of thin-walled parts or micro/nano structures. Induction heating is an efficient way to heat material by means of an electric current that is caused to flow through the material or its container by electromagnetic induction. It has various applications such as heat treatment, brazing, welding, melting, and mold heating. The present study covers an experimental investigation of induction heating in order to rapidly raise the mold temperature. It is observed that the mold surface temperature is raised up to $200^{\circ}C$ in 2 seconds. This induction heating is applied to injection molding of a flexspline for a plastic harmonic drive, which has difficulty in cavity filling because its minimum thickness is only 0.35 mm. The induction heating is then successfully implemented on this ultra-thin wall molding by raising the mold surface temperature around the glass-transition temperature of the molding material.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.15-16
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• 2016

Ways to efficiently manufacture gloss exposed mass concrete at an inexpensive price, in other words, ways to paste transparent transfer paper onto the surface of a combined mold has been designated as New Technology Article 191 by the Ministry of Land, Infrastructure and Transport. But if the difference in the coefficient of linear expansion between the mold's and transfer paper's material causes temperature to rise or fall, a wrinkly surface can appear. Therefore this study, by experimentally comparing the deformation characteristics between the mold material and transfer paper material upon changes in temperature, seeks to serve as a basic reference point for selecting the optimal transfer paper for different mold types. Study results revealed that for molds, polyester resin transfer paper is optimal, and for aluminum molds, acrylic resin transfer paper is.

• Journal of Power System Engineering
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• v.20 no.5
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• pp.5-13
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• 2016

This study is on wear damage of the material for a molding machine that be used at finally cutting of metal beam made in roll forming process of vehicle bump beam process line. SKD11 steel was used with the material for cutting mold jig. In the cutting mold jig, Ti diffusion heat treatment after vacuum heat treatment was carried out for upgrade of surface hardness and anti-wear. Also, the heat treatments by various methods were performed to compare the wear damage degree against above the existing heat treatment. Wear loss and friction coefficient were obtained from wear test. And, micro Vickers hardness values were compared with damaged parts or not of cutting mold jig. Micro Vickers hardness value appeared higher at the undamaged part by Ti diffusion heat treatment. The micro Vickers hardness well followed a two-parameter Weibull probability distribution.

• Korean Journal of Metals and Materials
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• v.48 no.6
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• pp.551-556
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• 2010

In this report, we describe mold materials that were used to produce movable metal type by the investment casting method during the Joseon dynasty period in Korea. Samples were obtained from the Wibuinja collection, which is held by the National Museum of Korea. Most of the mold material remnants were found in the depressed areas of the movable type specimens, and we therefore performed non-destructive analyses including XRF, EDS, and XRD. Through these analyses, we were able to identify the mold remnants as hydrocerussite [trilead dihydroxide dicarbonate, $Pb_3(CO_3)_2(OH)_2$] formed in platy hexagonal crystallites. Hydrocerussite was first used to make white pigments and cosmetics in ancient Greece, but this is the first report of hydrocerussite used as mold material applied around a disposable pattern for investment casting. The results of this study will further the understanding of the production process for early movable metal type and ancient casting technologies.

• Transactions of Materials Processing
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• v.20 no.1
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• pp.29-35
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• 2011

In the design of the injection molding process, various parameters including mold design parameters and molding conditions should be investigated to improve part quality. The mold temperature is one of important processing parameters that affect the flow characteristics, surface appearance, part deformation, mechanical properties, etc. Numerical analyses have been used to predict the temperature distribution of the mold under the given cooling or heating conditions. However, conventional analyses have been performed by assuming that the mold material is a single solid even though a number of plates are assembled to construct an injection mold. In the present study, a numerical approach considering the thermal contact resistance is proposed to provide more reliable prediction of the mold temperature distribution by reflecting the heat-resistance between assembled mold plates.