• 기술사
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• 제31권5호
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• pp.110-120
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• 1998

The effect of heat treatment and the order of antioxidants treatment toward the thermally oxidized palm oil which has been stored at 60 $^{\circ}C$ was studied. The summerized results of this study are as follows; 1. In the accelerated autoxidation condition, tocopherol showed no distinct effect on the changes of peroxide of value between added tocopherol samples pre-and post treatment by heating. But, rosemary extract showed opposite result. It was supposed that rosemary extract had lower thermostability then tocopherol, because rosemary extract lost it's antioxidative activity during heating process. 2. The changes of acid value and anisidine value were more affected by heat treatment than the order of antioxidant treatment. 3. The oxidative stability measured by OSI showed same tendency as peroxide value. That is, the antioxidative activity of tocopherol in palm oil was more dependent on addition of antioxidants than heat treatment, but the rosemary extract had opposite character for antioxidative action in palm oil.

• 대한의용생체공학회:의공학회지
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• 제11권2호
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• pp.295-304
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• 1990

In order to use for artificial dental tooth (dental crowens) , new glass-ceramics material has been studied. Its basic composition and the condition of heat treatment for crystalization, mechanical and chemical properties were investigated. Adding of the LAS system composition in the basic glass, time and temperature for crystalization were shortened. Fracture toughness (kic)of samples heat treated at 90$0^{\circ}C$ for 2 hours is 2.5-2.6MN/m3/2, the optimum condition of heat treatment for artificial tooth is A and B samples heating to 75$0^{\circ}C$ for 2 hours, raising to 90$0^{\circ}C$ and maintaining at 90$0^{\circ}C$ for 2 hours and C sample heating to 75$0^{\circ}C$ maintaining at 75$0^{\circ}C$ for 2 hours. In acid and'alkali solution, chemical durability is excellent.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 고액공존금속의 성형기술 심포지엄
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• pp.16-27
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• 1997

A semi-solid forming has a lot of advantages compared to the die casting, squeeze costing and convenctional forging, therefore, semi-solid forming process are now becoming of industial interest for the production of metal components and metal matrix composites. However, the material behaviour in the semi-solid temperature range is not sufficiently known although it controls the whole process through forces and geometry evolutions bcause the behaviour of metal slurries is complex. The semi-solid materials(SSM) fabricated under electric-magnetic stirring condition is necessary to be applicate in forming process. A reheating conditions were studied with the reheating time, holing time and reheating temperatures. The microstructure of SSM (which specimen size:d 40${\times}$i60) on condition of heating time 10min and heating temperature 590$^{\circ}C$ is most globular and finest one. The microstructure of SSM(specimen size:d75${\times}$i60) reheated under the three step reheating conditions is most globular and finest.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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• pp.59-60
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• 2015

In this study, stress-strain, thermal expansion strain, total strain and high temperature creep strain of ultra-high-strength concrete with compressive strengths of 80, 130, and 180MPa were experimentally evaluated considering elevated temperature and loading condition. Also, transient creep strain has been calculated by using the results of experiment. Experimental coefficient K was proposed with application of non-steady state creep model. It is considered that the experimental results of this study could be baseline data for deformation behavior analysis of ultra-high-strength concrete.

• 한국기계가공학회지
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• 제11권6호
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• pp.75-81
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• 2012

Dissimilar material friction welding such as STD11 and SCM440, we are considering of such things as strength and tenacity of welding interface, which consist of friction welding rotation frequency, friction heating pressure, upset forging-pressure, friction heating time, and upset forging-pressure time. From the study, obtaining the interrelationship between welding condition and quality(toughness, tenacity), we can set the best range of welding condition. while performing acoustic emission examination for the nondestructive evaluation, we can deduce the interrelationship among total acoustic emission counts, friction welding variable, and quality during friction welding, which can solve the manufacturing difficulty and enhance the economic value.

• 대한기계학회논문집A
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• 제34권5호
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• pp.575-582
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• 2010

최근 박육사출성형이나 마이크로 사출성형에서의 성형성을 높이기 위해 급속 금형가열 기술이 사용되고 있다. 고주파 유도가열은 전자기 유도현상을 이용하여 금형 표면만을 효율적으로 가열할 수 있어 급속 금형가열 기술로서 활용되고 있다. 본 연구에서는 고주파 유도가열 적용 사출성형 과정의 수치적 모사를 위해 전자기장 해석, 열전달 해석, 사출성형 유동해석을 연계한 통합적 전산모사 기법에 관한 연구를 수행하였다. 본 연구에서 제안된 통합적 전산모사 기법을 유도가열 적용 박육 사출성형의 해석에 적용하여 실험결과와 비교하였고, 특히 금형온도 경계조건의 부여방식에 따른 해석의 신뢰성에 대한 고찰이 이루어졌다.

• KIEAE Journal
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• 제14권2호
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• pp.11-19
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• 2014

Building energy consumption takes up almost 25% of the total energy consumption. Therefore, diversified ways, such as improving wall and window insulation, have been considered to reduce building energy consumption. Recently, green roof system has been explored as an effective alternative for dealing with reducing heating and cooling energy, thermal island effect and improving water quality. However, recent studies regarding a green roof system have only focused on building energy reduction without considering the applied usage, location, and story of the green roof system. Therefore, this study pays attention to the heating and cooling energy in relation to the applied usage, location, and story of a green roof system for investigating its impact on energy reduction. The result of simulations show that the reduction in heating energy consumption is higher when applied to Cherwon-gun province which has a continental climate condition, compared to the city of Busan that is distinguished by its warm climate. Cooling energy saving turns out to be higher when the green roof system is applied to Busan in comparison with Cherwon. As for the applied usage or function of the building, residential space acquires the highest heating and cooling energy saving effect rather than commerce, educational or office space because of HVAC's running time based on usage. When it comes to the story of the green roof, both heating and cooling energy saving become the highest when the green roof is applied to single-storied buildings. The reason is that single story building is affected by the ground largely. Generally, the variations of heating energy consumption are larger than the cooling energy consumption. The outcome of the simulations, when a green roof system is applied, indicates that the energy consumption reduction rate is dynamically responding to the applied usage, location, and story. Therefore, these factors should be counted closely for maximizing the reduction of energy consumption through green roof systems.

• 생태와환경
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• 제38권3호통권113호
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• pp.334-340
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• 2005

The chemical forms of Cd, Cu, Pb, and Zn were analysed by sequential extraction technique to evaluate the effects of drying and heating of dredged sediments from Lake Chungcho. The most abundant fraction of Cd, Cu, and Zn in the wet and untreated sediment was organic/sulfidic fraction that is state in reducing environment such as the bottom condition of Lake Chungcho, while Pb dominated in residual fraction. This means that the source of Cd, Cu, and Zn in the Chungcho lake sediment is related to the organic degradation and Pb to the erosion from surrounding rocks. With drying and oxidation by dredging, heating treatment, and disposal of the lake sediment, the chemical forms of studied metals changed greatly from organic/sulfidic fraction to adsorbed and reducible fractions which are more labile in oxygenated environment. Organic/sulfidic fraction of Cd, Cu and Pb in the wet sediment was transformed with drying and heating treatments to the labile ones like adsorbed and reducible fraction, but Zn to carbonate and reducible fraction. Heating of the sediment at $320^{\circ}C$ greatly increased the labile fraction of Cd and Cu, while that at $105^{\circ}C$ for Pb and Zn. It is believed that the increase in labile forms of heavy metals in the sediments by drying and heating is caused by the contact with oxygen during drying and heating and by the increase of pH of the pore water at the expense of organic/sulfidic fraction. It is concluded that the drying and oxidation currently used in the treatment of dredged sediment can increase labile forms of heavy metals in the sediment, and the potential of the metal availability from the sediment.

• 한국강구조학회 논문집
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• 제23권5호
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• pp.569-579
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• 2011

지역난방 시스템의 주요 구성요소의 하나인 열배관은 크게 공급관과 회수관으로 구분되며, 지역난방에서의 열수송 배관은 난방수의 온도변화에 따른 열응력을 받게 되므로 공용년수 증가에 따라 열응력에 의한 피로현상이 발생하게 된다. 한편 지역난방 열배관은 사용자배관의 공용조건에 따라 다양한 특성을 나타내며 이러한 불규칙한 온도변화는 열배관의 피로에 악영향을 미치게 된다. 따라서 본 연구에서는 기 매설된 공용중인 지역별 열배관에 대해 현장계측을 실시하고 각 지역의 데이터를 분석하였다. 또한 사이클기반 피로평가법 및 응력기반 피로평가법을 통하여 지역난방 열배관의 피로안전성을 평가하였다.

• 한국식품영양과학회지
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• 제32권8호
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• pp.1193-1199
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• 2003

아밀로오스 함량이 22%인 일반 옥수수전분과 아밀로오스 함량이 46%인 고아밀로오스 옥수수 전분을 이용하여 난소화성 전분의 제조과정 중 가열온도, 수분함량, 저장온도 및 가열-냉각회수 인자들이 난소화성 전분생성율에 미치는 영향을 반응표면분석법으로 분석한 결과 고아밀로오스 옥수수 전분이 옥수수 전분에 비하여 높은 난소화성 전분의 생성율을 나타내었다. 본 실험조건에서 고아밀로오스 옥수수 전분의 난소화성 전분 생성 최적 제조조건은 6회의 가열-냉각, 2$0^{\circ}C$의 저장온도, 108$^{\circ}C$의 가열온도 및 57%의 수분함량이었으며 생성율은25%수준이었다. 난소화성 전분의 제조시 영향을 미치는 순서는 가열-냉각회 수, 수분함량, 가열온도, 저장(냉각)온도 순이었다. 난소화성 전분의 제조과정에서 전분입자의 파괴 및 다공성 망상구조를 보였으며 비표면적의 증가와 평균직경의 감소현상이 나타났고 열처리에 의하여 색깔은 어두워지고 노란색상의 증가를 보였다. 가열-냉각 과정에서 옥수수 전분의 경도, 응집성, 탄력성 및 점성의 감소현상이 두드러졌다.