• Composites Research
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• v.34 no.5
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• pp.269-276
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• 2021

PCM (Prepreg Compression Molding) process is a high-speed molding technology that can manufacture high-quality CFRP (Carbon Fiber Reinforced Plastic) parts. Compared to the autoclave process, it generates less waste and can significantly reduce cycle time, so various studies are being conducted in the aerospace and automobile industries. In this study, in order to improve the quality of the PCM process, a molding method was developed to increase the compression pressure of the press step by step according to the curing behavior of the prepreg. It was confirmed that this multi-stage compression molding technology is a good means to produce high-quality CFRP products and shorten cycle times. And, the laminated prepreg at room temperature was immediately put into the mold and preheated and molded at the same time, so that it could be molded without a separate preheating process. In addition, as a result of applying the same process conditions optimized for flat plate molding to three-dimensional shapes, a product similar to a flat plate in appearance could be made without the process of establishing process conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.703-704
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1121-1122
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.183-184
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• 2009

• The Magazine for Energy Service Companies
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• s.21
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• pp.20-23
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• 2003

목포 대불공단에 위치한 케이씨㈜(구, 한국화학)는 작년 10월부터,올 1월까지 응축수회수시스템, 감압 및 트랩개선, 보일러 공기예열기 설치 등 공정개선 ESCO사업을 시행해 연간 약 3억9천만원에 달하는 에너지비용을 절약하고 있다. 자금력과 전문인력확보가 어려운 중소기업에 있어서 ESCO사업은 자금부담을 크게 줄일 수 있을 뿐 아니라 ESCO의 우수한 맨파워를 활용함으로써 전문기술력을 제공받는 효과가 기대된다.

• Korean Journal of Agricultural Science
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• v.7 no.2
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• pp.103-108
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• 1980

In order to elucidate the source of bacterial contamination during processing U. H. T. milk and to ensure its hygienic control, bacterial numbers were determined each step of the processes on the milks, water, tanks and pipe lines, and environments. The results obtained were as follows. 1. The viable numbers of mesophilic bacteria were $1.2{\sim}1.9{\times}10^7/ml$ of milk in the storage tank and in pipe line connected to the preheater. These were decreased to $7.0{\times}10cells{\sim}3.4{\times}10^2cells/ml$ after preheating and homogenization, and to $1.0{\times}10cells/ml$ after sterilization, then increased up to $1.2{\times}10^2cells/ml$ after packing. 2. The numbers of thermophilic bacteria were $5.0{\times}10cells{\sim}1.0{\times}10^2cells/ml$ of milk before preheating ; $3.0{\sim}5.0{\times}10cells/ml$ after homogenization ; none in the sterilizer and surge tank ; and $1.0{\sim}8.0{\times}10cells/ml$ after packing. 3. The levels of psychrophilic bacteria were $1.0{\sim}3.7{\times}10^6cells/ml$ of milk before preheating ; $1.0{\sim}4.0{\times}10cells/ml$ after homogenization ; $1.0{\times}10cells/ml$ after sterilization ; and $2.0{\times}10cells{\sim}2.5{\times}10^2cells/ml$ after packing. 4. No coliform bacteria were detected after sterilization, while the level before preheating was $2.1{\times}10^4cells{\sim}6.5{\times}10^5cells/ml$ of milk. 5. The level of mesophiles was $3.0{\times}10cells{\sim}7.4{\times}10^2cells$ in the environmental air, water supply, and unfilled packs and bottles ; that of thermophiles $1.0{\sim}3.0{\times}10cells$ in the air and water ; that of psychrophiles $1.0{\times}10cells{\sim}1.0{\times}10^2cells$ in the air, water, packs and bottles ; however no coliform was detected.

• Journal of Convergence for Information Technology
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• v.10 no.2
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• pp.82-88
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• 2020

The purpose of this study is to obtain basic data on the optimization of firing process conditions for enamel coating in chemical heat exchanger. The method of increasing the firing temperature in order to apply enamel coating to shell & tube type heat exchanger was examined. The temperature distribution of the heat exchanger in the firing kiln was numerically calculated using a commercial CFD program. The structural safety of the heat exchanger was confirmed by thermal stress analysis using the FSI method. Numerical analysis and experimental results show that there is a problem of safety due to temperature difference when the heat exchanger at room temperature is directly put into a firing kiln at 860℃. Therefore, a preheating process is need to reduce the temperature difference. As in Case2 with fewer firing steps, the first stage preheating temperature of 445℃and the second stage firing temperature of 860 ℃are considered to be most suitable.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.267-267
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• 2006

전력에 큰 손실을 초래하는 고장전류를 차단하기 위한 한류기(FCL) 소재로서 고온 초전도체인 BSCCO 2212가 사용된다. 고온에서 용융된 BSCCO 2212 분말은 원심성형법에 의해 한류기용 튜브로 제조되었다. BSCCO 튜브의 기계적 특성을 높이고 용융온도를 낮추기 위해 $SrSO_4$(10wt-%)를 첨가하였다. 용탕은 $1200^{\circ}C$에서 완전히 용융되어 금속 몰드로 주입되었고 원심성형에 사용되는 금속 몰드는 $550^{\circ}C$ 온도로 2시간 예열 후 1020 ~ 2520 RPM으로 회전시켰다. 원심력에 의해 성형된 BSCCO 튜브는 약 48시간 동안 로에서 서냉 후 금속 몰드로부터 분리하였다. 튜브의 용이한 분리를 위해 이형제로서 BSCCO 2212 powder를 사용하였고 임계전류측정을 고려하여 Ag tape 단자를 튜브 끝단에 부착하였다. BSCCO 제조 공정에 있어서 몰드의 예열온도, 용융온도, 몰드 회전속도 등의 변수를 조절하여 최적의 조건을 확립하였다. 제조한 BSCCO 튜브의 임계전류($I_c$)와 임계전류밀도($J_c$)는 77K에서 536A와 $205A/cm^2$ 이었다. 본 연구에서는 BSCCO 2212 튜브를 제조하는 공정조건 변화와 각 조건에서 제조된 BSCCO 2212 튜브의 전기적 특성 및 그에 따른 분석에 대해 기술하였다.

• Korean Journal of Food Science and Technology
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• v.22 no.6
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• pp.659-667
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• 1990

Starch acetates were prepared by conventional method, preheat treatment, and extrusion process through acetylation of corn starch with acetic anhydride and their physicochemical properties were investigated. The optimal conditions of the acetylation of starch by conventional method(CSA) was found that starch concentration was 30%, reaction temperature $35^{\circ}C$ and pH 8.5. With increasing the molar ratio of acetic anhydride to anhydrous glucose unit from 0.03 to 0.20, DS(Degree of substitution) value of corn starch acetate prepared at the optimum condition was increased from 0.019 to 0.080, while the acetylation efficiency was decreased from 31.6% to 20.5%. In the case of the preheated (gelatinized), then acetylated starch(PSA), DS value was increased from 0.027 to 0.04 at the fixed molar ratio of the acetic anhydride with increasing preheating temperature from $60^{\circ}C\;to\;90^{\circ}C$. The DS was low as 0.02 in the case of starch acetate prepared by extrusion process(WESA). The CSA and PSA showed lowering gelatinization temperature and enthalpy than raw corn starch with increasing DS. All of starch acetates showed the increased degree of transparency, the decreased lightness and the increased yellowness as compared to the raw corn starch. WESA showed lower apparent viscosity and more close to the characteristic of the Newtonian fluid than CSA and PSA. Intrinsic viscosity was reduced in CSA and WESA, although PSA has a slightly higher one than raw corn starch. The rate of retrogradation of the gels was retarded in all starch acetates.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2003.05a
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• pp.365-369
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• 2003

이산화탄소 규제 대응 전략으로, 배출되는 온실가스를 분리, 회수, 처리하는 연구가 지속적으로 진행되고 있다. 현재 이산화탄소 저감 연구는 공정개발 초기부터 이산화탄소 배출을 방지하거나 분리하기 쉬운 형태로 설계하는 방식으로 전환되고 있다. 그 예로 고온 순산소 연소 시스템이 제안되었다. 이는 $CO_2$를 가장 효과적으로 저감시키는 방법 중의 하나로 연소에 사용되는 산화제로 순산소를 사용하여 원료를 절감할 수 있고 산소를 사용하기 때문에 배가스 중에 질소분율이 감소하여 배가스에 의한 현열손실을 줄일 수 있으며 또한 배가스 현열을 회수하여 산소를 고온으로 예열시켜 에너지를 추가적으로 절감할 수 있다. 이를 위해 산소를 선택적으로 투과시켜 고순도 산소를 제조할 수 있을 뿐만 아니라 산소제조 장치비를 절감할 수 있는 ITM (Ion Transport Membrane) 신소재 및 산소 투과 공정을 개발하고자 한다.