• Title/Summary/Keyword: heat-resistant

검색결과 613건 처리시간 0.029초

CrW 전율고용체 첨가 내열 알루미늄 합금에 관한 연구 (The Study of Heat Resistant Aluminum Alloy with CrW Homogeneous Solid Solution)

  • 김진평;성시영;한범석;김상호
    • 한국주조공학회지
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    • 제33권3호
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    • pp.122-126
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    • 2013
  • Recently, heat-resistant aluminum alloy has been re-focused as a downsizing materials for the internal combustion engines. Heat-resistant Al alloy development and many researches are still ongoing for the purpose of improving thermal stability, high-temperature mechanical strength and fatigue properties. The conventional principle of heat-resistant Al alloy is the precipitation of intermetallic compounds by adding a variety of elements is generally used to improve the mechanical properties of Al alloys. Heat resistant aluminum alloys have been produced by CrW homogeneous solid solution to overcome the limit of conventional heat resistant aluminum alloy. From EPMA, it is found that CrW homogeneous soild solution phases with the size of $50-100{\mu}m$ have been dispersed uniformly, and there is no reaction between aluminum and CrW alloy. In addition, after maintaining at high temperature of 573 K, there is no growth of hardening phase, nor desolved, but CrW still exists as a homogeneous solid solution.

시스플라틴 내성세포주에서 열충격에 의한 세포사멸에 관한 연구 (Heat Shock Induces Necrosis in Cisplatin-resistant Gastric Cancer Cells through Suppressing JNK1/2 Activation and HSP27 Induction)

  • 임성철;최철희;한송이
    • 생명과학회지
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    • 제19권12호
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    • pp.1705-1711
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    • 2009
  • 항암제 내성을 획득한 암세포는 많은 경우 다양한 세포 독성 물질에 대해 교차 내성을 나타낸다. 그러나 온열 치료가 내성 획득 종양에 적용 될 때의 종양 세포의 사멸 효과는 알려져 있지 않다. 본 연구는 시스플라틴에 내성을 갖는 위암 세포 주, SNU601/Cis2이 열충격에 반응하는 민감도와 세포 사멸 방식을 조사함으로써 약물 내성 종양의 온열 치료 효과를 예측하고자 하였다. 정상 위암 세포 주 SNU601/WT은 열충격에 매우 민감하게 반응하며 apoptosis로 사멸하지만, 내성 위암 세포 주 SNU601/Cis2는 미열충격에 내성을 나타내었으며 고열충격에 노출되자 necrosis로 사멸하였다. 또한 SNU601/Cis2에서 necrosis의 발생은 열충격에 의한 JNK1/2의 활성화와 HSP27의 발현저하 현상과 관련되어 있었다. Necrosis의 유도는 세포막 파괴에 의해 세포 내부 물질의 방출로 인한 주변 조직의 염증반응을 수반하는데, 이러한 염증 반응은 암의 성장을 촉진하고 암의 성상을 심화시키는 것으로 보고되고 있다. 이러한 관점에서, 온열 치료가 약물 치료와 병행 될 경우에는 교차 내성과 necrosis로 인한 역효과를 방지하기 위하여, 그 적용이 주의 깊게 이루어져야 할 것으로 판단된다.

오스테나이트계 내열 스테인리스강의 용접성 평가에 관한 연구 (The Study on Evaluation of Weldability of Austenitic Heat Resistant Stainless Steel)

  • 변경일;지병하;정호신
    • 한국해양공학회:학술대회논문집
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    • 한국해양공학회 2000년도 추계학술대회 논문집
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    • pp.236-239
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    • 2000
  • It is important to evaluate austenitic heat resistant stainless steel because of low weldability of austenitic heat resistant stainless steel containing high Si. This study took varestraint test for evaluation of solidification cracking sensitivity and Erichsen test for evaluation of weld metal ductility. As a result of tests, solidification crack sensitivity increased with adding $N_2$ to shielding gas, and W had detrimental effect on crack resistance, but Ce had beneficial effect on crack resistance. Under same heat input, ductility of weld metal increased with welding speed.

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시판 식물성 식품의 오염지표세균 분포 및 저장온도, 기간별 오염지표세균의 변화 (Distribution of Indicator Organisms and Influence of Storage Temperature and Period in Commercial Plant Food)

  • 이용욱;박석기
    • 한국식품위생안전성학회지
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    • 제14권1호
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    • pp.1-8
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    • 1999
  • There were few data for the distribution of the indicator organisms in the commercial plant foods, and for the normal flora and for the foodborne agents within the country. First of all it must be investigated the distribution of the indicator organisms. And also it is very important to prepare the sanitation criteria for the plant foods through the microbiological examination and the investigation of tendency to change of the indicator organisms according to the storage temperature and period. The average number of total viable counts for grains was 2.9$\times$105/g, psychrophilic bacteria 2.9$\times$105/g, heterotrophic bacteria 3.1$\times$105/g, heat-resistant bacteria 2.1$\times$103/g, Pseudomonas aeruginosa 23/g. That for beans was 6.3$\times$102/g, psychrophile 34/g, heterotroph 1.7$\times$102/g. That for sesames was 1.4$\times$105/g, coliform 350/g, psychrophile 7.4$\times$104/g, heterotroph 5.8$\times$104/g, Pseud. aeruginosa 2.3$\times$103/g. heat-resistant bacteria 150/g. That for potatoes was 2.0$\times$107/g, coliform 5.0$\times$104/g, psychrophile 1.8$\times$107, heterotroph 1.4$\times$107/g, heat-resistant bacteria 3.3$\times$104/, Staphylococcus 2.7$\times$105/g, fecal streptococcus 4.5$\times$103/g, Pseud. aeruginosa 7.0$\times$103/g. That for mushrooms was 1.2$\times$108/g, psychrophile 9.4$\times$107/g, heterotroph 1.0$\times$109/g, heat-resistant bacteria 1.6$\times$105/g, Pseud. aeruginosa 1.3$\times$103/g. That for vegetables was 5.9$\times$1011/g, coliform 1.8$\times$106g/, Staphylococcus 1.1$\times$1012/g, heterotroph 8.4$\times$1011/g, heat-resistant bacteria 7.6$\times$106/g, Staphylococcus 1.1$\times$107/g, fecal streptococcus 1.1$\times$104/g, Pseud. aerugniosa 5.2$\times$104/g. That for nuts 3.9$\times$104/g, coliform 3.9$\times$103/g, psychrophile 4.0$\times$104/g, heterotroph 3.2$\times$104/g, heat-resistant bacteria 400/g. In commercial grains and beans, SPC, psychrophile, heterotroph and heat-resistant bacteria stored at 1$0^{\circ}C$, 2$0^{\circ}C$, 3$0^{\circ}C$ were constant. Staphylococcus, coliform, Pseud. aeruginosa were decreased a little n grains, but were not detected in beans. In mushrooms, all indicator organisms were increased as time goes on and were increased rapidly at 2$0^{\circ}C$. In sesames, coliform was not detected at all temperature. psychrophile was increased for 7 days, the others were constant. In potatoes, SPC, psychrophile, heat-resistant bacteria, heterotroph had a tendency to increase and the others were constant. In vegetables, indicator organisms were had a tendency to increase, psychrophile, heterotroph were rapidly increased after 7 days. In nuts, SPC, coliform, psychrophile heterotroph, heat-resistant bacteria, Pseud. aeruginosa were constant, staphylococcus and fecal streptococcus were not detected.

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산청고령토와 장수곱돌 슬러지를 사용한 내열소지 개발 (Development of heat resistant body using Sanchung Kaolin and Jangsu gobdol sludge)

  • 김상곤
    • 한국결정성장학회지
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    • 제30권1호
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    • pp.27-32
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    • 2020
  • 점토, 규석, 장석을 사용하여 만든 전통생활도자기는 주 결정상이 mullite와 cristobalite이다. Mullite 결정은 제품의 강도를 좋게 하지만 열팽창계수가 5.3 × 10-6/℃로 비교적 커서 내열 도자기로는 사용할 수 없다. 본 연구에서는 산청토와 장수곱돌 sludge를 사용하여 도자기 내에 mullite 결정 대신 열팽창 계수가 2.6 × 10-6/℃인 cordierite 결정이 생성되게 함으로써 가벼운 내열 도자기를 개발하고자 하였다. 그 결과 산청토 80 wt%, 장수곱돌 sludge 20 wt%를 사용하여 만든 도자기가 내열성이 좋고 강도와 하중연화도 우수하였으며, 부피비중도 1.7 8로 기존의 분청사기보다 가벼웠다.

알루미늄 함량에 따른 알루미늄 주철의 내산화성에 관한 연구 (A Study on the Oxidation Resistance of Aluminum Cast Iron by Aluminum Content)

  • 김동혁
    • 한국주조공학회지
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    • 제40권6호
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    • pp.135-145
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    • 2020
  • Aluminum cast iron has excellent oxidation resistance, sulfurization resistance, and corrosion resistance. However, the ductility at room temperature is insufficient, and at temperatures above 600?, the strength drops sharply and practicality is limited. In the case of heat-resistant cast iron, high-temperature materials containing Cr and Ni account for 30 to 50% or more. However, these high-temperature materials are expensive. Aluminum heat-resistant cast iron is considered as a substitute for expensive heat-resistant materials. Oxidation due to the aging temperature and holding time conditions increases more in 0 wt.% Al-cast iron than in 2 and 4 wt.% Al-cast iron according to oxidized weight and gravimetric oxide layer thickness measurements. As a result of observing the cross-section of the oxide layer, it was found to contain 0 wt.% of Al-cast iron silicon oxide-containing SiO2 or Fe2SiO4 oxide film. In cast iron containing aluminum, the thickness of the internal oxide layer due to aluminum increases as the aging temperature and retention time increase, and the amount of the iron oxide layer generated on the surface decreases.

고온 이산화황 환경 내 내열 크롬강에 대한 부식특성 연구 (High Temperature Corrosion Properties of Heat Resistant Chrome Steels in SO2 Atmosphere)

  • 이한상;정진성;김의현
    • 대한금속재료학회지
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    • 제47권2호
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    • pp.99-106
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    • 2009
  • The high temperature corrosion properties of heat resistant steels were investigated in oxidation atmosphere including sulfur dioxide. The heat resistant steels of T22, T92, T122, T347HFG and T304H were evaluated at 620, $670^{\circ}C$ for 400 hours. The corrosion rates showed a decreasing tendency while chrome contents of those steels increased from 2 mass.% to 19 mass.%. The in crease in temperature increasement has an more effect on the corrosion rates of low chrome steels than high chrome steels. The weight gains of T22, T92, T304H at $670^{\circ}C$ were 3.7, 1.65, 1.23 times compared with those at $620^{\circ}C$. The external scale formed on T22 was composed of hematite, magnetite and Fe-Cr spinel and internal layer including iron oxide mixed with sulfide. The scales formed on T92, T122, T304H consisted of an outer layer of hematite and inner layer of chrome oxide and hematite. The proportion of chrome oxide at inner layer was increased when the chrome contents in heat resistant steels were increased.

비행체 추진기관용 내열 복합재의 특성 및 개발 동향 (Characteristics and Development Trends of Heat-Resistant Composites for Flight Propulsion System)

  • 황기영;박종규
    • 한국항공우주학회지
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    • 제47권9호
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    • pp.629-641
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    • 2019
  • 고온, 고압의 연소가스에 의해 유입되는 많은 열을 효과적으로 차단하여 고체 로켓 노즐의 공력형상을 최대한 유지하면서 구조물의 온도 상승을 일정수준 이하로 제한하기 위해 연소가스와 접하는 위치에 내삭마성이 우수한 C/C 복합재 등의 내열재를, 그 배면에는 열확산계수가 낮은 단열재를 적용한다. 내산화성이 우수한 SiC/SiC 복합재는 가스터빈 엔진에 적용되고 있으며, 경량화와 내열성 향상으로 인해 엔진 성능 증가에 기여하고 있다. 극초음속으로 비행하는 스크램제트는 흡입 공기 온도가 매우 높아서 흡열 연료를 냉각제로 사용하는 C/SiC 구조물 개발 연구가 수행되고 있다. 본 논문에서는 고체 로켓 노즐, 가스터빈 엔진 및 램제트/스크램제트 추진기관에 사용되는 다양한 내열 복합재의 특성, 적용사례 및 개발 동향을 고찰하였다.

XRD 분석을 이용한 고온가열 무기계 내화 접착제의 성분검토 (Examination of Ingredients of High Temperature Heat Resistant Inorganic Fire-Resistant Adhesive Using XRD Analysis)

  • 조현서;지우람;신기돈;이건철
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2018년도 추계 학술논문 발표대회
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    • pp.81-82
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    • 2018
  • The structure of the RC structure is actively reinforcing the structure of the building which has suffered from aging, artificial and natural damage of the building. Among various reinforcement methods, epoxy adhesive is used to attach FRP in FRP reinforcement method which is reinforcing by attaching FRP to the structural part. At this time, the epoxy adhesive having a low critical temperature has a sudden adhesive failure upon exposure to heat, and thus, the development of an inorganic fireproof adhesive having a high critical temperature has progressed. Therefore, in this study, the compositional change of inorganic fire - resistant adhesive exposed to high temperature heat was analyzed by XRD.

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A Study on Heat Resistance of High Temperature Resistant Coating

  • Zhang, Liping;Wang, Xueying;Zhang, Qibin;Qin, Yanlong;Lin, Zhu
    • Corrosion Science and Technology
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    • 제4권2호
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    • pp.60-63
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    • 2005
  • A high temperature resistant coating has been developed, which is mainly for heavy oil production pipes deserved the serious corrosion. The coating has excellent physical and mechanical performance and corrosion resistance at room and high temperature. In order to simulate the underground working condition of heavy oil pipes, the heat resistance of the high temperature resistant coating has been studied. The development and a study on the heat resistance of the DHT high temperature resistance coating have been introduced in this paper.