• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.220-221
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• 2017

In this study, the thermal strain of high strength concrete with the compressive strength of 70, 80, 100MPa were measured under 33% of compressive strength loading condition. As results, it is considered that shrinkage strain of high strength concrete become grater at the elevated temperatures.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.235-238
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• 2005

In this study, it is investigated that the effect of material properties such as strength coefficient and strain hardening exponent on formability of AZ31 alloy sheet in square cup deep drawing process. Mechanical properties of AZ31 alloy sheet at elevated temperature $250^{\circ}C$ are obtained from uniaxial tensile tests and based on these results, a series of square cup deep drawing tests at the same temperature condition are carried out. Also, the possibilities of necking initiation is predicted by the FEM and FLD and compared with experimental results.

• 한국압력기기공학회 논문집
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• 제12권1호
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• pp.107-114
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• 2016

Four cylindrically shaped IHXs(Intermediate Heat Exchangers) are installed in the PHTS(Primary Heat Transfer System) of the PGSFR(Prototype Gen IV Sodium cooled Fast Reactor). As for the IHX, the temperature difference of structure is inevitable result caused by heat transfer between primary coolant sodium and IHTS(Intermediate Heat Transport System) sodium. It is necessary to evaluate the high temperature structural integrity of IHXs which operate at the elevated temperature condition over the creep temperature. In this paper, the high temperature structural integrity of IHX under assumed loading conditions has been reviewed according to ASME code.

• 한국환경과학회지
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• 제23권6호
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• pp.1003-1012
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• 2014

We examined the combined impacts of future increases of $CO_2$ and temperature on the growth of four marine diatoms (Skeletonema costatum, Chaetoceros debilis, Chaetoceros didymus, Thalassiosira nordenskioeldii). The four strains were incubated under four different conditions: present ($pCO_2$: 400ppm, temperature: $20^{\circ}C$), acidification ($pCO_2$: 1000ppm, temperature: $20^{\circ}C$), global warming ($pCO_2$: 400ppm, temperature: $25^{\circ}C$), and greenhouse ($pCO_2$: 1000ppm, temperature: $25^{\circ}C$) conditions. Under the condition of higher temperatures, growth of S. costatum was suppressed, while C. debilis showed enhanced growth. Both C. didymus and T. nodenskioldii showed similar growth rates under current and elevated temperature. None of the four species appeared affected in their cell growth by elevated $CO_2$ concentrations. Chetoceros spp. showed increase of pH per unit fluorescence under elevated $CO_2$ concentrations, but no difference in pH from that under current conditions was observed for either S. costatum or T. nodenskioeldii, implying that Chetoceros spp. can take up more $CO_2$ per cell than the other two diatoms. Our results of cell growth and pH change per unit fluorescence suggest that both C. debilis and C. didymus are better adapted to future oceanic conditions of rising water temperature and $CO_2$ than are S. costatum and T. nodenskioeldii.

• Composites Research
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• 제33권5호
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• pp.275-281
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• 2020

본 논문에서는 항공기 팬 블레이드에 적용되는 복합재와 금속 간의 접합 구조물에 대한 온도, 습도에 따른 접착제의 물성 변화에 관해 연구하였다. 항공기 운용 시 노출되는 환경 조건을 고려하여 상온 건조(Room Temperature Dry, RTD), 고온 흡습(Evaluated Temperature Wet, ETW), 저온 건조(Cold Temperature Dry, CTD) 세가지 환경에서 강도 시험을 수행하였다. 접착전단강도 시험은 ASTM D3528을 기준으로 수행하였고, 파손 영역에 대한 마이크로 구조 특성을 SEM이미지를 통해 분석하였다. 연구 결과에 따르면 RTD 환경에서의 전단강도 대비하여 ETW 환경에서 72.8% 저하되었으며, CTD 환경에서는 56.5% 증가되었다. 이는 고온 및 수분 흡습이 접착제의 기계적 특성에 큰 영향을 미치는 것을 확인했고, 저온 환경에서는 모재와 접착제 모두 취성의 증가로 인해 접착 전단 강도가 향상된 것으로 분석되었다.

• Steel and Composite Structures
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• 제15권6호
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• pp.705-724
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• 2013

The behaviour of steel column at elevated temperature is significantly different than that at ambient temperature due to its changes in the mechanical properties with temperature. Reported literature suggests that steel column may become vulnerable when exposed to fire condition, since its strength and capacity decrease rapidly with temperature. The present study aims at investigating the lateral load resistance of non-insulated steel columns under fire exposure through finite element analysis. The studied parameters include moment-rotation behaviour, lateral load-deflection behaviour, stiffness and ductility of columns at different axial load levels. It was observed that when the temperature of the column was increased, there was a significant reduction in the lateral load and moment capacity of the non-insulated steel columns. Moreover, it was noted that the stiffness and ductility of steel columns decreased sharply with the increase in temperature, especially for temperatures above $400^{\circ}C$. In addition, the lateral load capacity and the moment capacity of columns were plotted against fire exposure time, which revealed that in fire conditions, the non-insulated steel columns experience substantial reduction in lateral load resistance within 15 minutes of fire exposure.

• 환경생물
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• 제32권2호
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• pp.95-101
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• 2014

한반도의 낙엽성 참나무인 졸참나무(Quercus serrata)의 생태적 지위폭이 $CO_2$ 농도와 온도가 상승하였을 때 광, 수분 그리고 영양소 구배에서 어떻게 변화하는지 알아보고자 유리온실에서 대조구와 온난화처리구로 구분하여 재배한 후, 유식물의 20가지 형질을 측정하고 생태적 지위폭을 계산하였다. 그 결과, 생태적 지위폭은 광구배에서 대조구보다 온난화처리구가 넓어졌고, 수분과 영양소 구배에서는 대조구보다 온난화처리구가 좁아졌다. 이것은 지구온난화 진행 시 졸참나무는 광 환경에 대한 내성이 증가되고, 수분과 영양소 환경에 대한 내성이 감소될 것으로 예측할 수 있다. 주성분분석(PCA) 결과, 각 환경 구배에서 요인 1과 요인 2에 의해 대조구와 온난화처리구가 구분되었다. 생태학적 반응은 다양한 형질이 종합적으로 관여하며, 그 중에서 식물의 생산량을 나타내는 형질이 많은 부분 관여하는 것으로 판단된다.

• 한국항공우주학회지
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• 제38권11호
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• pp.1115-1122
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• 2010

본 논문에서는 샌드위치-적층판 단일겹침 접착 조인트의 정적강도를 시험을 통해 연구하였다. 접착제의 두께(3종류 : 0.2, 2, 4 mm)와 환경조건(2가지 : 상온, 고온흡습)을 변화시키면서 총 38개의 시편을 제작하여 시험을 수행하였다. 시험 결과, 접착제의 두께가 0.2mm에서 2 mm 와 4 mm로 증가함에 따라 체결부의 파손강도가 각각 16% 와 30% 정도 감소하는 것으로 나타났다. 반면 고온흡습 환경에서의 파손강도는, 접착제의 두께가 0.2mm인 경우를 제외하면, 접착제의 열화현상이 적층판과 샌드위치 면재의 층간분리 혹은 층내분리 파손을 지연시켜, 상온건조 환경에 비해 약 12% 가량 높게 나타났다. 접착제의 두께가 얇은 0.2 mm의 경우 시험환경의 효과는 나타나지 않았다.

• 한국연초학회지
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• 제7권2호
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• pp.129-139
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• 1985

cent was carried out to study on the effect of temperature and humidity to chemical tobacco leaves during the yellowing stage. The results were follows : In the condition of high humidity and low temperature, yellowing time was delayed ; leaf color appeared lack clearness. In the higher temperature and the lower humidity during the yellowing stage : total sugar, reducing sugar and malic acid content were increased. Decomposition of nitrogenous components elevated in $38^{\circ}C$, 85%RH. Changes of total nitrogen content correlated with total curing time. Adecrease of linolenic acid with a corresponding increase of chlorogenic acid proceeded in the condition of low temperature and high humidity. In a view of tobacco quality by chemical components, the low temperature and high humidity during the yellowing stage decreased quality of tobacco leaves. It is considered to control of the proper condition of temperature and humidity during the yellowing.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 춘계학술대회 논문집
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• pp.301-306
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• 2001

In this paper, friction welding optimization for 1Cr0.5Mo to STS304 and AE applications for the weld quality evaluation were investigated The important results of this study are as follows : 1. The techiques for dissimilar friction welding optimization if the elevated temperature materials 1Cr0.5Mo and STS304 and its real-time weld quality evaluation by AE were developed, considering on both strength and toughness. 2. Quantitative relationship was identified among welding condition, weld quality and cumulative AE counts.