• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.298-307
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• 2006

TEE Forming process for HDPE(High Density PolyEthylen) pipe has been analyzed by using rigid plastic finite element code, DEFORM-3D. TEE of HDPE pipes is necessary to connect main pipe with branch pipe and change the flow direction of hot water. A HDPE pipe is used as a insulator to maintain the temperature of hot water A butt welding process through TEE forming for a HDPE pipe is a updated process improving the strength of welding part compared to conventional extrusion welding process. The Experiment of Hot and Cold Forming have been performed. The design parameters such as a initial hole shape have been obtained through rigid-plastic finite element analysis, which is applied to the actual manufacturing process.

• Korean Journal of Food Science and Technology
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• v.27 no.2
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• pp.164-169
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• 1995

Fictitious experiment to control extrusion process was carried out using the fuzzy theory. Algorithm of the fuzzy logic controller(FLC) was made based on the general principles of extrusion. In the simulation, at first, thickness of extrudate was measured as feedback input variable. Secondly, a set point of screw speed was determined as output variable of extruder operating condition through FLC. Finally, the thickness of extrudate was controlled as a given set point. Barrel heater was simply controlled as on/off state, which was not fuzzy controlled.

• Journal of the Korean Ceramic Society
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• v.37 no.11
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• pp.1114-1118
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• 2000

Ti 및 C 입자로 이루어진 다공질 성형체에 용융 Si의 침윤 및 반응으로 새로운 Ti$_3$SiC$_2$합성공정이 개발되었다. 용융 Si 침윤에 의한 Ti$_3$SiC$_2$합성공정에서는 이제까지 연구된 합성방법 보다 넓은 조성 범위에서 Ti$_3$SiC$_2$의 합성이 이루어졌다. 용융 Si을 활성 매질로 사용한 Ti$_3$SiC$_2$의 합성에서는 성형체 조성, 원료 입자 크기 및 침윤되는 용융 Si의 양에 따라 합성되는 상 및 각 합성상의 양이 다르게 나타났다. Ti:Si:C=3:1:6 조성을 제외한 모든 조성의 시편에서 Ti$_3$SiC$_2$상이 합성되었으며, 일부 조성을 제외한 모든 조성의 시편에서 Ti$_3$SiC$_2$, TiC 및 SiC가 함께 합성되었다. 작은 Ti 입자로 이루어진 성형체를 사용하여 합성한 시편에서 Ti$_3$SiC$_2$상의 합성이 용이하게 이루어졌으며, 성형체 조성 및 침윤되는 Si의 양이 화학양론적으로 Ti$_3$SiC$_2$에 근접한 조성을 갖는 시편에서 Ti$_3$SiC$_2$를 높은 수율로 합성할 수 있었다.

• Korean Journal of Food Science and Technology
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• v.37 no.5
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• pp.757-762
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• 2005

Characteristics of cereals prepared by extrusion-cooking and freeze-drying were compared. Parameters used were water solubility index (WSI), water absorption index (WAI), paste viscosity, and sterilization. Variables for extrusion process were barrel temperature at die section (70, 90, and $110^{\circ}C$) and moisture content (25 and 30%). WAI and WSI of extruded cereals were higher, whereas trough, breakdown, and final viscosity were lower than those of raw and freeze-dried cereals. Plate counting revealed no microbes in extruded cereals, whereas microbe colony was observed in freeze-dried cereals. Extrusion-cooking at low temperature resulted in better sterilization of microbes than freeze-drying for preparation of instant cereal drinks.

• 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.

• Composites Research
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• v.35 no.2
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• pp.93-97
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• 2022

The application of infrared heating in the hot press forming of the thermoplastic composites is conducive to productivity with high-speed heating. However, high energy, high forming temperature, and high-speed heating derived from infrared heating can cause material degradation and deteriorate properties such as re-melting performance. Therefore, this study was conducted to optimize the process conditions of the hot press forming suitable for carbon fiber reinforced polyetherketoneketone(CF/PEKK) composites that are actively researched and developed as high-performance aviation materials. Specifically, the degradation mechanisms and properties that may occur in infrared high-speed heating were evaluated through morphological and thermal characteristics analysis and mechanical performance tests. The degradation mechanism was analyzed through morphological investigation of the crystal structure of PEKK. As a result, the size of the spherulite decreased as the degradation progressed, and finally, the spherulite disappeared. In thermal characteristics, the melting temperature, crystallization temperature and heat of crystallization tend to decrease as degradation progresses, and the crystal structure disappeared under long-term exposure at 460℃. In addition, the low bonding strength was observed on the degraded surface, and the bonding surfaces of PEKK did not melt intermittently. In conclusion, it was confirmed that the CF/PEKK composite material degraded at 420℃ in the infrared high-speed heating. Furthermore, the spherulite experienced morphological changes and the re-melting properties of thermoplastic materials were degraded.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.11
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• pp.1327-1335
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• 2017

This study was carried out to determine the effect of cacao bean addition on the physicochemical properties of extruded rice flour. Rice-based cacao beans (0, 20, 40, 60%) were extruded at a die temperature of $130^{\circ}C$, screw speed of 200 rpm, and moisture content of 25%. As the content of cacao beans increased from 20% to 60%, expansion index decreased, while piece density and specific length increased. The water soluble index and water absorption index of the extrudate increased through extrusion cooking. Lightness decreased as cacao bean content increased while redness increased. As the content of cacao beans increased, paste viscosity decreased. Cold peak viscosity was observed in all extrudates of raw roasted cacao beans. ${\alpha},{\alpha}$-Diphenyl-${\beta}$-picrylhydrazyl (DPPH) radical-scavenging activity increased upon extrusion and cacao bean addition. As content of cacao beans increased, non-roasted cacao beans had higher total phenolic contents than roasted cacao beans. This study showed that addition of cacao beans to extruded rice snack improved antioxidant activity.

• Composites Research
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• v.16 no.3
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• pp.1-8
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• 2003

Densification occurs by the inelastic flow of the matrix materials during the consolidation processes at high temperature for MMCs, and the results depend on many process conditions such as applied pressure, temperature and volume fraction of fiber and matrix materials. This is particularly important in titanium matrix composites since material failure may occur by either the applied conditions or microstructural parameters through the processes, and thus a generic model based on micro-mechanical approaches enabling the evolution of density over time to be predicted has been developed. The mode developed is then implemented into FEM so that practical process simulation has been carried out. Further the experimental investigation of the consolidation behavior of SiC/Ti-6Al-4V composites using vacuum hot pressing has been performed, and the results obtained are compared with the model predictions.

• 기계와재료
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• v.23 no.3
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• pp.82-95
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• 2011

다결정압연판재는 열가공공정을 거쳐서 생산되므로 공정의 특성을 반영하는 미세조직/집합조직 특성을 가지게 된다. 결정립들은 특정방향으로 배향하고 결정립의 형상과 크기도 변화한다. 이러한 변화는 거시적으로 다결정판재의 이방성으로 귀결이 되는데, 근본적으로 판재를 구성하는 단결정들의 기계적 물성이 각각의 방향별로 이방성을 띄기 때문이다. 본 자료에서는 압연공정시 다결정판재의 수직/평면이방성의 발생원인을 집합조직과 결정소성학을 이용하여 제시하고자 하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.35-35
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• 2015

AZ31B 마그네슘 합금 판재를 이용하여 자동차 부품을 가공하는 경우에는 판재를 성형하고 이를 접합하여 복잡한 형태의 부품을 만들게 되는데, 대부분의 경우에서 전착도장 공정을 필수로 거치게 된다. 그리고 전착도장 공정은 기존의 자동차 생산 공정에 사용되는 도료 및 공정을 그대로 이용하여야 하며, 현재까지 연구된 결과에 의하면 마그네슘 소재의 전착도장은 전착도장 공정 전에 행해지는 화성처리 공정이 적절하게 처리되었다면 공정상 별다른 문제를 발생시키지 않는다. 즉 마그네슘의 화성처리는 전착도장 공정과 전착도장된 제품의 내식성에 매우 중요한 요소이다. 이러한 화성처리 공정은 화성처리 공정 전단계의 표면 전처리 공정에 크게 영향을 받게 되는데, 본 연구에서는 AZ31B 마그네슘 함금 판재의 전처리-화성처리-전착도장으로 구성되는 마그네슘 표면처리에 있어서 전처리 공정중 산에칭 공정이 화성처리-전착도장의 최종 물성에 미치는 영향에 관하여 조사하였다.