• 대한기계학회논문집
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• 제19권1호
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• pp.79-86
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• 1995

The structural materials for cryogenic technology have been recently developed to support the many modern large-scale application from superconducting magnets for nuclear fusion reactor, magnetic levitation railway to LNG tankers. However it is pointed out that quenching phenomenon is one of the serious problems for the integrity of these applications, which is mainly attributed to the rapid temperature rising in the material due to some extrinsic factors of structures. From the viewpoint of fracture mechanics, it is therefore very important to clarify the mechanism of temperature rising of structural material due to cyclic loading at cryogenic temperature. From this purpose, fatigue test was carried out for high manganese steel at liquid helium temperature(4.2K) using triangular stress waveform to identify both the mechanism of temperature rising near crack tip and the effect of loading stress waveform on temperature rising near crack tip and the effect of loading stress waveforms on temperature rising. As the results, two types of temperature rising, that is, regular and burst types were observed. And a periodical temperature rising corresponding to the stress waveforms was also found. The peaks of the temperature rising were recorded near both the maximum and the minimum values of the applied stress. The sudden temperature rises, which indicated the higher values than those of periodical temperature rises under the repetition of stress, were observed at the final region of crack growth. It was shown that the peak values of the temperature rising increased with stress intensity factor range.

• 아시안잔디학회지
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• 제17권4호
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• pp.165-172
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• 2003

본 연구는 녹지의 배치와 식재형태가 기온저감효과에 미치는 영향을 파악한 결과 다음과 같은 점이 밝혀졌다. 1) 녹지의 기온분포도로부터 고온역은 주변시 가지에서, 저온역은 각 녹지내의 식재지주변과 소하천주변에서 확인되었다. 2) 녹지의 배치와 기온과의 관계를 보면, 저온역은 각 녹지와 거의 일치하고 녹지간 시가지 및 풍하쪽에도 저온역이 형성되었다. 3) 녹지간 시가지와 기온과의 관계를 보면 저온역은 풍하쪽 시가지뿐 아니라 녹지간 시가지에서도 나타났다. 또한, 풍상쪽에 녹지가 존재하지 않은 경우에도 녹지간 시가지는 주변 시가지 보다 낮은 기온이었다. 4) 토지피복비율과 기온에서 식재지, 초지 및 수면이 증가하면 모두 기온저감에 효과적이고, 나지의 증가는 기온상승에 효과적이다. 5) 교목, 소교목의 순으로 그 그루의 증가는 기온저감에 유효하게 관련되어 있는 것이 파악되었다.

• KIEAE Journal
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• 제15권3호
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• pp.5-14
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• 2015

Purpose: Recently, according to climate changes, human health is exposed to danger over the world and they influence all fields of human society. Due to these climate changes, humans can be exposed to more frequent and extreme scorching heat and cold wave than the present. As precautions against these urban higher temperature and dryness, diverse methods are being sought. Among them, as measures to form cold islands, the evaporative cooling effect realistic to social and economic conditions was examined. Method: This study was conducted to analyze effects of temperature reduction and cooling according to injection quantity of minute water particles by using a blast sprayer as one of alternatives of alleviation of urban climate changes in outside space in summer. For this, through temperature difference in accordance with the injection quantity per hour of a day, a time zone representing the value of the highest temperature change was analyzed. Also, by analyzing temperature difference according to the injection quantity per daytime insolation, relation of amounts of insolation and evaporation was investigated. Temperature difference in accordance with distances at the highest temperature with the highest value in temperature changes was analyzed. Result: At the study result, about temperature, as injection quantity increase, temperature reduction was significant statistically at the highest temperature with the most insolation. A factor with the highest influence was judged to be the increase of the injection quantity. According to the injection quantity, it was predicted that $3.1^{\circ}C$ temperature reduction of a daily average in case of 0.16L/min, $3.5^{\circ}C$ temperature reduction of a daily average in case of 0.32L/min, and $4.4^{\circ}C$ temperature reduction of a daily average in case of 0.48L/min.

• 한국지역사회생활과학회지
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• 제24권4호
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• pp.583-589
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• 2013

This study was to provide the information for optimum utilization of the air-conditioning system in the human health and energy saving perspective. Subjects were 17 male and female college students(7 males and 10 females) with normal weight. They wore a short sleeved shirt, knee length trousers, socks, and underwear(0.4clo). They were asked to choose the preferred temperature from different environmental temperatures($28^{\circ}C$, $25^{\circ}C$). The physiological responses were measured and the subjective sensation was voted during the step changes of environmental temperature, starting at $28^{\circ}C$ to $25^{\circ}C$ with $1^{\circ}C$ decrease every 20 minutes. The preferred temperature was $25.9{\pm}0.4^{\circ}C$ for males and $26.9{\pm}0.2^{\circ}C$ for females at $28^{\circ}C$ and $24.8{\pm}0.6^{\circ}C$ for males and $25.6{\pm}0.1^{\circ}C$ for females at $25^{\circ}C$. The preferred temperature decreased about $1.3^{\circ}C$ while the environmental temperature changed $3^{\circ}C$. During the environmental step changes, mean skin temperature decreased more in females while the oxygen uptake and rectal temperature were kept constant for both males and females. We found the preferred temperature was affected by the exposed temperature and the thermal sensation in the condition. Subjects preferred a lower environmental temperature when they were exposed to a lower temperature with cooler sensation. Therefore, in the perspective of human health and energy saving, it is recommended to start setting the air-conditioning temperature higher than the preferred temperature.

• 동력기계공학회지
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• 제19권6호
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• pp.47-53
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• 2015

Korea is the geographic location during the summer, the temperature rising to $35^{\circ}C$ and winter temperature is $-15^{\circ}C$ to reduce the air temperature changes, such as relatively large compared to other countries. This increase or decrease of the harmful exhaust gas discharged from automobile substantially inconvenience a significant impact on the active side of the car engine temperature and exhaust gas reducing device receives a large impact on the atmospheric temperature is regulation to be different. However, domestic vehicle emissions test temperature of $20{\sim}30^{\circ}C$ is it does not reflect this situation the actual test temperature to accurately measure the exhaust gas volume of the vehicle is difficult. In this study, domestic automobile exhaust gas test conditions of a test temperature $20{\sim}30^{\circ}C$ various temperatures, including (35, 25, 0, -7, -15, $-25^{\circ}C$) under the two vehicles (2.0L MPI, 2.4 L GDI) as was discussed with respect to the exhaust gas characteristics of the vehicle according to the ambient temperature gas. As a result, domestic emissions test temperature of $25^{\circ}C$ than average conditions were temperature decreases greenhouse gas emissions and increase overall increased by up to 15 times higher. Air temperature and the engine exhaust gas inconvenience a direct effect on the activation temperature required in the reduction unit is determined to be an increase of emissions and greenhouse gases, and also an increase in the variety of lubricants based lubricating and viscosity reduction, such as the engine oil due to the low temperature of these result It is considered that shows the.

• 지구물리와물리탐사
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• 제21권2호
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• pp.82-93
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• 2018

저수지 안전진단을 위하여 수행되는 전기비저항 모니터링 자료는 대기의 온도에 영향을 받는다. 특히 국내와 같이 사계절의 온도 변화가 큰 환경에서는 지중온도 변화에 의한 전기비저항의 변화를 무시하기 어렵다. 따라서 온도효과는 전기비저항 모니터링 자료의 정밀한 해석을 어렵게 한다. 이 연구에서는 저수지에서 획득된 다점온도 모니터링 자료를 분석하여 시공간적 지중온도를 추정하고, 이를 이용하여 역산 결과 얻어진 지하 전기비저항 모델에 대하여 온도보정을 수행하였다. 온도보정 결과, 계절변화에 의한 온도 효과는 주로 상부에 국한되며, 심부에서는 무시할 수 있는 것으로 해석되었다. 그러나 댐 제체의 온도 분포만을 가지고 온도 보정을 수행하면 그 효과를 완전히 제거할 수 없다. 이 문제를 극복하기 위해, 저수지 물의 온도 변화에 의한 효과는 대기온도 변화도 함께 포함되어야 할 것으로 보인다.

• 대한지리학회지
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• 제46권3호
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• pp.257-276
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• 2011

이 연구에서는 극한기온 지수의 변화 경향을 분석하여 도시화 효과가 극한기온의 변화에 미치는 영향을 규명하고자 하였다. 한국에서 60개 기상관측지점을 대상으로 극한기온과 관련된 16개의 지수를 분석하였다. 여름철 관련 극한기온 지수값은 대부분 증가하였고, 겨울철 관련 극한기온 지수값은 감소하였다. 여름철 지수 중 변동 임계치를 갖는 지수가 열대야와 같은 고정 임계치를 갖는 경우보다 증가 경향이 더 뚜렷하였다. 겨울철과 관련된 극한기온 지수값의 감소 경향이 여름철과 관련된 극한기온 지수의 증가 경향보다 뚜렷하였다. 이는 도시의 기온이 여름철보다 겨울철에 더 상승하는 것과 비슷한 결과이다. 일최고기온과 관련된 지수의 증가 경향보다 일최저기온과 관련된 지수의 감소 경향이 뚜렷하다. 이런 결과도 도시에서 최고기온보다 최저기온의 상승 경향이 더 뚜렷한 것과 비슷한 경향이다.

• Journal of the Korean Wood Science and Technology
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• 제25권4호
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• pp.99-107
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• 1997

This study was executed to test the possibility of replacement for domestic Japanese larch(Larix leptolepis) for hardwoods and to acquire the information about the effects of drying temperature on internal temperature, moisture content and drying defects. In high-temperature drying, internal temperature increased rapidly to boiling point, immediately after that point the internal temperature rising rate was reduced. In the case of drying at temperature of $125^{\circ}C$, internal temperature could reach at boiling point in a very short time. Moisture content in high-temperature drying showed constant drying rate period and first period of falling rate drying together in 4 hours since experiment begun. There was no strong correlation between initial moisture content and final moisture content. Average drying rate at $115^{\circ}C$, $120^{\circ}C$ and $125^{\circ}C$ was 1.42%/hr, 1.88%/hr and 2.02%/hr, respectively; the case of drying temperature of $125^{\circ}C$ showed most rapid drying rate. Drying rate of $125^{\circ}C$ was so rapid that it showed more severe shrinkage, bow, collapse, end check, and internal check development than in other drying conditions. The result of this study showed the strong possibility of high-temperature drying for Japanese larch, and to dry Japanese larch optimally, dry bulb temperature should not exceed $120^{\circ}C$.

• 산업식품공학
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• 제23권2호
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• pp.87-93
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• 2019

공기 주입식 스팀-에어 레토르트 내에서 스팀온도, 내부가압, CUT 등의 공정변수가 레토르트 내부의 온도 균일성에 미치는 영향을 평가하였다. 고온살균(121℃)이 저온살균(82℃) 보다 공정구간동안 온도분포가 더 균일하고 안정적이었다. 내부 가압이 클수록 저온살균조건의 공정에서는 온도분포가 안정적이었고, 이와 반대로 고온살균조건의 공정에서 온도분포가 더 불균일한 것으로 나타났다. 승온구간을 조절한 경우에는 레토르트 내의 온도분포에는 유의적인 차이를 나타내지 않았다. 공정구간동안 레토르트 내부에서 냉점은 수직방향 1층의 위로 확인되었고, 수평방향에서는 맨 뒤쪽 중앙 부분이 가장 높은 온도를 유지하여 공정 동안 이 위치들을 주의를 할 필요가 있었다. 또한 레토르트 내부의 양 옆 위치가 다른 위치에 비해 특히 온도분포가 불안정한 것으로 확인되었으므로 레토르트 가공 공정에서 주의해야 할 것으로 판단되었다.

• Journal of Mechanical Science and Technology
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• 제14권1호
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• pp.11-18
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• 2000

Fracture toughness JIC and KIC tests were performed on A516 Gr70 carbon steel plate at the temperature ranging from -$160^{\circ}C$ to $600^{\circ}C$, and test results were analyzed according to ASTM E 813 and ASTM E 399. Unloading compliance J-integral tests were performed on 1TCT specimens. The relation between the $J_{IC}$ value and the test temperature was obtained. It was concluded that the temperature ranging from $-15^{\circ}C$ to $600^{\circ}C$ is the upper shelf region of ductile-brittle transition temperature, and in this temperature range, fracture toughness $J_{IC}$ values decreased with increasing temperature. The ductile brittle transition temperature of the material may be around $-30^{\circ}C$. In the region near $-30^{\circ}C$, the tendency of $J_{IC}$ to decrease with decreasing temperature was significant.