• The Korean Journal of Rheology
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• v.10 no.2
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• pp.113-120
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• 1998

사출성형공정은 대표적인 고분자 가공공정으로 그 복잡한 특성으로 인하여 공정변 수를 최적화하는 것을 주로 경험에 의존해 왔다. 본 연구에서는 사출성형공정의 보압과정 중에 보압의 이력을 최적화하여 제품각 부분의 부피수축율차이를 최소가 되게 하는 최적화 시스템을 개발하였다. 최적화 알고리즘으로는 GA방법을 사용하였으며 본 연구에서 제안한 최적화 시스템으로 보압과정의 최적화를 수행한 결과 부피수축율의 차이가 현저히 감소하는 것을 알수 있었다. 특히 SA방법을 사용하는 경우 초기의 최적화 속도가 GA를 사용하는 경 우에 비해서 뛰어남을 알수 있었다. 또한 충전과정과 보압과정을 함께 최적화하여 보압과정 만 최적화한 결과와 비교하여 보았다.

• Journal of the East Asian Society of Dietary Life
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• v.6 no.1
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• pp.85-92
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• 1996

The sensory and instrumental characteristics of Jeung-pyun made from various additives were investigated to improve the qualify of Jeung pyun and to know the effects of additives on Jeung-pyun preparation. In sensory evaluation of Jeung-pyun made from various additives, hardness was significantly lower by addition of soy bean flour, whole milk powder, and egg yolk. The cell uniformity of Jeung-pyun was significantly lower by addition of egg yolk and mugwort. And the dgree of bitterness Jeung-pyun containing soy bean flour and mugwort flour were significantly higher than that of control. Retrogradation of Jeung-pyun assessed from DSC thermogram and hardness measured by texturometer was delayed by addition of soy bean flour, and whole milk powder.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.5789-5794
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• 2015

Recently, thin and light-weight production technologies are needed in IT industry in accordance with increase of the smart phones and mobile PC products. In order to make light and high rigidity products, engineering plastic and aluminum materials are frequently used in products appearance and frame hat support structure. Especially aluminum extrusion and CNC Brick processes are widely used for high strength and high rigidity technology. But extrusion method has constraints to apply exterior design and CNC Brick process has relatively high production cost and low speed of manufacturing. In this research, a new process method is introduced in order to reduce material cost and to improve manufacturing speed dramatically. Plate forging process means basically that thickening of local wall area thickness after deform exterior shape by deep drawing and bending process. Therefore, it is possible to minimize the waste of material and the manufacturing time. In this study the process of plate forging is designed using finite element program AFDEX-2D and the thickness and the width of initial deformed blank. And it is verified as a sample which is a part of laptop developed through the proposed plate forging method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.7
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• pp.1340-1347
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• 2002

Finite element simulations are being widely used to increase the efficiency and effectiveness of design of bulk metal forming processes. In such simulations, proper consideration of friction condition is crucial in obtaining reliable results. For this purpose, tip test based on backward extrusion was proposed recently. In this lest, a cylindrical billet is positioned in a shallow groove of a counter punch for centering purpose and formation of a radial tip is induced on the extruded end of the workpiece. In this study, the effect of centering groove on tip test was investigated. The quantitative ratio of the shear friction factors between the punch and die was numerically determined depending on the shape of centering groove. Also, surface expansion and pressure distribution along the punch and die were considered in order to better understand the reason that friction condition at the punch compared to the one of die was more severe.

• Composites Research
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• v.23 no.6
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• pp.61-66
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• 2010

In this paper, the variation of mechanical properties of T800 carbon/epoxy composites according to the forming pressure, which was referred to previous studies on a filament winding process, were investigated. The specimens of all the tests were fabricated by an autoclave de-gassing molding process controlling forming pressure (absolute pressures of 0.1MPa, 0.3MPa, 0.7MPa including vacuum) and water jet cutting after fabricating composite laminates. Various tensile tests were performed for in-plane properties and interlaminar properties were also measured by using Iosipescu test jig. Fiber volume fraction was measured to correlate the property variation and the forming pressure. This properties are expected to be utilized in the design of Type III pressure vessel for hydrogen vehicles which uses the same carbon fiber (T800 carbon fiber) for the filament winding process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.395-399
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• 2017

The LPI fuel filter housings used in automobiles were made from conventional die castings but have recently been developed by cold forging to improve the weight and durability. On the other hand, a sink may develop at the core of the forged product due to the resulting T-shape, which not only reduces the aesthetics, but also increases the post-processing cost of the product. Therefore, this research focused on methods to predict and mitigate sink development and progression during the T-shape forging process. Finite element analysis of the forging process was first performed to determine the optimal initial workpiece devoid of burrs and underfills. An accurate sink prediction was then obtained via metal flow analysis, which was a result of the finite element simulation. Through finite element analysis, it was confirmed that sink development is a product of the differences in nodal velocities arising from the T-shaped forging process. Consequently, a pad was inserted beneath the sink to minimize these velocity differences. The results yielded significant improvement with regard to the sink defect. This method was practically applied to an industrial site to validate the sink improvement.

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.5
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• pp.525-533
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• 1992

To improve the food quality of traditional Jeung-pyun(Korean fermenfed rice cake), effect of mixed ingredients on the quality of protein enriched product was studied. Changes were evaluated in chemical and textural properties of protein enriched Jeung-pyun altered by fermentation time, temperature, and steaming time. The maximum volume wxpansion was noted in dough mixed with rice flour(100 g), soy flour(25 g), sucrose(20 g), Tak-ju(50 ml) and water(10 ml), and then fermented at $35^{\circ}C$ for 3 hours. Soy protein isolate(SPI) enriched rice dough had a maximum expanded volume when 15g(w/w) of SPI, 20g(w/w) of sucrose, 60ml(v/w) of Tak-ju and 50ml(v/w) of water added into 100g rice flour, and then fermented at $30^{\circ}C$ for 2 hours. Steaming after fermentation made the smaller volume of bulk $45^{\circ}C$-50% of the initial volume be showed just after fermentation. Protein enriched Jeung-pyun prepared under the maximal volume endowing conditions showed the best protein quality(protein digestibility and protein efficiency ratio) and starch structure which was susceptible towards enzyme reaction. The improved starch quality of protein enriched Jeung-pyun could be confirmed by reducing power, gelatinization degree and amylose content. Jeung-pyun riched with soy flour at 20% level or with SPI at 5% showed the best overall quality by sensory and textural property but it had a problem in browning.

• Composites Research
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• v.16 no.1
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• pp.1-12
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• 2003

This study developed SiC$_{p}$/A1$_2$O$_3$$_{f}$/Al composites for electronic packaging to which reinforcements were added with the volume fractions of 49%, 56% and 63% by the squeeze casting method. 0.8 wt. % of the inorganic binder as well as the A1$_2$O$_3$ fiber and SiC Particles with the volume fraction of 1:10 were added to the composites, which were produced in the newly designed mold. For the produced SiC/Al composites, the CTEs (coefficients of thermal expansion) were measured from 30 to 300 and compared with the FEM numerical simulation to analyze the temperature dependent properties. The experiment showed the CTEs of SiC$_{p}$/A1$_2$O$_3$$_{f}$/Al composites that were intermediate values of those of Rule of Mixture and Turner's Model. The CTEs were close to Turner's Model in the room temperature and approached the Rule of Mixture as the temperature increases. These properties analyzed from the difference of the average stress acting between the matrix and the reinforcements proposed in this study.

• Korean journal of food and cookery science
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• v.13 no.1
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• pp.64-69
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• 1997

The experiments of rice bread processing were carried out to compare the varietal difference in processing adaptability to rice bread between brown and milled rice flour, and to analyze the interrelations among chemical properties of rice grain and some characteristics relevant to rice bread processing and quality There was varietal difference in adaptability to rice bread processing in both brown and milled rice, but there was not significant adaptability difference between brown and milled rice flours to rice bread processing. However, there was remarkable adaptability difference between brown and milled rice flours to rice bread processing in some rice varieties. Three high-amylose rices AC 27, IR 44, Suweonjo showed high quality of milled rice bread among tested rice materials. Brown rice revealed better adaptability to rice bread processing compared with milled rice in all varieties except the above three varieties. Especially, the glutinous rice Hangangchalbyeo failed to normal formation of rice bread from milled rice flour, but it showed the successful formation of rice bread from brown rice flour. The interrelations among chemical components of rice grain and some characteristics relevant to rice bread processing and quality exhibited quite different tendency between brown and milled rices. In the case of rice bread processing by brown rice flour, the larger volume expansion of dough during fermentation made the more springy rice bread and the more moist rice bread showed the more soft and cohesive physical property. In the case of rice bread processing by milled rice flour, the lower protein of rice flour was closely associated with the more moistness of rice bread and the higher lipid led to the more uniformal air pore distribution, the smaller pore size and the lower springiness of rice bread. Also, the larger volume expansion of dough during fermentation made the better loaf formation and the larger pore size of rice bread. The better loaf formation of rice bread revealed the softer hardness and the lower chewiness, and the lower springiness was closely correlated with the more uniformal size distribution of air pore and the smaller pore size in rice bread.

• Journal of the Korean Institute of Gas
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• v.8 no.2 s.23
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• pp.15-27
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• 2004

The purpose of this paper is to improve the performance of Polymer electrolyte fuel cell(PEMFC) by studying the channel dimension of bipolar plates using commercial CFD program 'Fluent'. Simulations are done ranging from 0.5 to 3.0mm for different size in order to find the channel size which shoves the highst hydrogen consumption. The results showed that the smaller channel width, land width, channel depth, the higher hydrogen consumption in anode. When channel width is increased, the pressure drop in channel is decreased because total channel length Is decreased, and when land width is increased, the net hydrogen consumption is decreased because hydrogen is diffused under the land width. It is also found that the influence of hydrogen consumption is larger at different channel width than it at different land width. The change of hydrogen consumption with different channel depth isn't as large as it with different channel width, but channel depth has to be small as can as it does because it has influence on the volume of bipolar plates. however the hydrogen utilization among the channel sizes more than 1.0mm which can be machined in reality is the most at channel width 1.0, land width 1.0, channel depth 0.5mm and considered as optimum channel size. The fuel cell combined with 2cm${\times}$2cm diagonal or serpentine type flow field and MEA(Membrane Electrode Assembly) is tested using 100W PEMFC test station to confirm that the channel size studied in simulation. The results showed that diagonal and serpentine flow field have similarly high OCV and current density of diagonal (low field is higher($2-40mA/m^2$) than that of serpentine flow field under 0.6 voltage, but the current density of serpentine type has higher performance($5-10mA/m^2$) than that of diagonal flow field under 0.7-0.8 voltage.