• 한국분말재료학회지
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• 제9권2호
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• pp.96-102
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• 2002

In the present study, equiatomic porous TiNi shape-memory alloys have been successfully prepared by self-propagating high-temperature synthesis (SHS) using elemental titanium and nickel powders. The porous TiNi alloys thus obtained have an open porous structure with about 64 vol.% porosity, and the pore size is about 1.8 mm. The effect of preheating temperature on the microstructure have been investigated. It is found that the pore size increases with increasing preheating temperature. Moreover, the preheating temperature was shown to have a significant effect on the microstructrue of the SHS-synthesized porous TiNi shape memory alloys.

• 대한치과기공학회지
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• 제6권1호
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• pp.11-14
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• 1984

The auther performed this experimental study on cervical margin distortion in preheating method during soldering. 1. In soldering methods, the method using the furnace has less distortion than the method using open-flame and longer the bridge spon, the larger the distortions. 2. Table Ⅰ Showed that buccal margin, lingual margin, mesial margin and distal margin had respectively 0.01mm, 0.02mm, 0.03mm, 0.03mm closer adaptation in 3 unit bridge than in 5 unit bridges. 3. Table II showed that buccal margin, lingual margin, mesial margin and distal margin had respectively 0.06mm, 0.07mm, 0.11mm, 0.05mm closer adaptation in 3 unit bridge than in 5 unit bridges.

• 한국세라믹학회지
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• 제33권2호
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• pp.235-241
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• 1996

Self-Propagating high temperature synthesis(SHS) technique was used to synthesize the spinel phase of MgAl2O from MgO and Al powder. Processing factors such as mixing time preheating temperature and ignition catalyst were varied to determine the optimum condition to form MgAl2O4 phase. The reaction products were heat treated at the temperature range of 120$0^{\circ}C$ and 150$0^{\circ}C$. to observe phase transformation of unreacted materials. Processing factors such as 48 hrs-mixing 80$0^{\circ}C$-preheating and 20wt% KNO3-ignition catalyst were effective of the formation of MgAl2O spinel. An activation energy 49.7kcal/mol. was calculated to form a MaAl2O4 spinel from unreacted materials.

• 한국정밀공학회지
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• 제28권12호
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• pp.1341-1346
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• 2011

Currently, many researches are carried out for laser assisted machining, which is one of the important fields in materials difficult to process. However, a prediction of heat source is difficult because of moving heat source. In this paper, a thermal analysis of laser assisted machining of plate by change of heat source size is performed, and preheating temperature by adjusting the feed rate is controlled. It was recognized that the maximum preheating temperature increases according to the decrease in heat source size, and feed rate need to adjust as high speed. The results of this analysis can be used as a reference for preheating temperature prediction in laser assisted milling.

• 한국산학기술학회논문지
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• 제19권5호
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• pp.570-576
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• 2018

철근콘크리트 구조물에서 철근의 이음은 철근을 겹쳐서 결속선으로 결속한 겹침이음과 커플러에 의한 기계적 이음이 일반적이다. 국내 설계기준(콘크리트구조기준)에서는 일반철근(비용접 철근)에 대해 용접 겹침이음을 제한하고 있으나, 해외기준(AWS D1.4)에서는 예열을 통한 일반철근의 용접 겹침이음을 허용하고 있다. 본 연구에서는 국내외 규격 및 설계기준을 조사하고, 건설현장에서 가장 많이 사용되는 SD400 강종의 일반철근을 대상으로 용접 겹침이음 인장실험을 수행하여 인장강도를 평가하였다. 용접 겹침이음 시험체의 용접길이는 KS규격(KS B ISO 17660-1)에 제시된 최소용접길이인 8d를 적용하고, 예열온도는 AWS D1.4에 따라 D19이하는 $150^{\circ}C$, D22이상은 $260^{\circ}C$로 설정하였다. 인장실험 결과, 용접 겹침이음된 일반철근은 콘크리트구조기준에서 요구하는 인장강도(항복강도의 125%)를 발현하였으며, 모두 철근 모재에서 파단이 발생되었다. 예열 유무에 따른 영향을 검토하기 위해, 일반철근을 예열한 후 용접한 것과 예열 등의 열처리하지 않은 것을 비교한 결과, 인장강도는 큰 차이를 보이지 않았다. 실험시 사용한 일반철근을 대상으로 화학성분을 분석하여 탄소당량(Ceq)을 확인한 결과, 0.45% 이하로 낮았다. AWS D1.4에 따르면, 탄소당량이 0.45% 이하면 예열이 필요하지 않은 조건이다. 결과적으로 예열의 영향이 미비한 것은 일반철근의 탄소당량이 낮았기 때문인 것으로 확인되었다.

• 한국식품영양과학회지
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• 제41권9호
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• pp.1310-1314
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• 2012

본 실험은 제초제 내성을 가지는 CP4EPSPS를 도입시킨 유전자재조합 콩을 이용하여 인공위액의 비율에 따른 도입 단백질의 소화특성을 평가하고, 열처리가 유전자재조합 콩의 도입단백질의 소화성에 미치는 영향을 살펴보았다. 유전자재조합 콩과 펩신의 비율에 따른 도입단백질 CP4EPSPS의 소화성은 인공위액 즉 펩신의 양에 따라 차이를 나타내 유전자재조합 식품의 도입단백질에 대한 소화성 평가에서 펩신의 양이 중요한 요인이 됨을 알 수 있었다. 또한 유전자 재조합 콩에 대한 예열처리가 도입단백질 CP4EPSPS의 펩신에 대한 내성을 많이 감소시켜 소화성을 높이는 것으로 나타났다. 따라서 앞으로 유전자재조합식품의 안전성을 평가하는 in vitro 소화평가 시험에서 생리학적 측면에 근거한 인공위액의 비율을 반영함으로써 보다 정확한 도입단백질의 소화성에 대한 평가가 필요하리라 사료되며, 또한 콩의 주요 섭취방법인 열처리에 따른 도입단백질의 소화특성을 평가함으로써 유전자재조합 콩의 안전성에 대한 신뢰도 제고를 위한 기초자료가 될 것으로 기대된다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2003년도 추계학술발표대회 개요집
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• pp.207-209
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• 2003

In FE analysis for residual stress of a casting, contact force between mould and casting material and gravity force must be considered for exact simulation. Preheating of a repair weldment had a little effects on the reduction of residual stress. However, preheating with hammer peening had a great deal of effects on the reduction of residual stress. A method for estimation of fatigue life for a repair weldment has been established.

• Journal of Welding and Joining
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• 제12권2호
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• pp.39-48
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• 1994

In comparison to the conventional brazing, laser welding of ceramics has advantages of direct bonding without filler material, which causes the thermal stress due to the differences of thermal expansion coefficients. In pulse-mode, laser welding of dispersion ceramic having high thermal resistance is possible at relatively low preheating temperature of $1300^{\circ}C$ In CW-mode, alumina can be welded at high preheating temperature $1500^{\circ}C$ under the condition of low feed rate of 500 mm/min, respectively. Further studies on developing mechanism of pores in the bead during laser welding of ceramics is required.

• 한국결정성장학회지
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• 제10권3호
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• pp.252-257
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• 2000

성장 전 GaAs기판의 열에칭 온도 변화에 따른 ZnS 에피층의 특성을 최초로 조사하기 위하여 450~$660^{\circ}C$로 열에칭한 기판 위에 hot wall epitaxy법으로 ZnS 에피층을 성장하였다. ZnS 에피층의 이중결정요동곡선의 반치폭은 기판의 열에칭 온도가 50$0^{\circ}C$와 $600^{\circ}C$일 때 가장 작았다. 그러나 ZnS 에피층의 photoluminescence(PL)특성은 기판의 열에칭 온도가 $500^{\circ}C$ 보다는 $600^{\circ}C$에서 더 양호하였다. 그러므로 고품질의 ZnS 에피층을 성장하기 위한 GaAs기판의 최적 열에칭 온도는 $600^{\circ}C$임을 알았다. 이러한 결과로부터 GaAs 기판의 열에칭은 $600^{\circ}C$에서 ZnS 에피층의 결정성과 PL특성에 좋은 영향을 주는 것으로 확인되었다.

• 한국축산식품학회지
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• 제36권5호
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• pp.671-678
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• 2016

Fractioning and/or preheating treatment on the rheological properties of myofibrillar protein (MP) gels induced by microbial transglutaminase (MTG) has been reported that they may improve the functional properties. However, the optimum condition was varied depending on the experimental factors. This study was to evaluate the effect of red bean protein isolate (RBPI) on the rheological properties of MP gels mediated by MTG as affected by modifications (fractioning: 7S-globulin of RBPI and/or preheat treatment (pre-heating; 95℃/30 min): pre-heating RBPI or pre-heating/7S-globulin). Cooking yields (CY, %) of MP gels was increased with RBPI (p<0.05), while 7S-globulin decreased the effect of RBPI (p<0.05); however, preheating treatments did not affect the CY (p>0.05). Gel strength of MP was decreased when RBPI or 7S-globulin added, while preheat treatments compensated for the negative effects of those in MP. This effect was entirely reversed by MTG treatment. Although the major band of RBPI disappeared, the preheated 7S globulin band was remained. In scanning electron microscopic (SEM) technique, the appearance of more cross-linked structures were observed when RBPI was prepared with preheating at 95℃ to improve the protein-protein interaction during gel setting of MP mixtures. Thus, the effects of RBPI and 7S-globulin as a substrate, and water and meat binder for MTG-mediated MP gels were confirmed to improve the rheological properties. However, preheat treatment of RBPI should be optimized.