• 한국인터넷방송통신학회논문지
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• 제11권1호
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• pp.61-65
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• 2011

최근 액정디스플레이는 TV, Monitor, Note PC를 비롯한 모든 디스플레이영역에서 활발하게 사용되고 있다. 그러나, 액정디스플레이의 배경광원으로 사용하는 평판조명장치(백라이트)에서 주로 사용하는 광원인 CCFL(냉음극방전관)의 경우 수은 가스를 사용하기 때문에 저온 환경에서의 구동특성에 한계를 갖고 있다. 본 연구에서는 이러한 CCFL 광원이 갖고 있는 문제점을 해결하기 위해서, LED 광원을 사용한 백라이트 조명장치를 고안하고, -40도의 극저온환경에서의 동작특성을 CCFL 광원을 사용한 백라이트 조명장치와 비교분석하여, 저온환경에서의 LED 백라이트의 효용성에 대해서 연구하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 추계 학술논문 발표대회
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• pp.47-49
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• 2012

Under this study, the characteristics of concrete intensity condition following the curing method under the extremely low temperature environment have been contemplated, and as a result, in the event of insulation + heat cable curing, the intensity and accumulated temperature accomplishment period is required for two times of requiring initial frost damage prevention than the case of heating + heat insulation curing method due to the insufficient calories supplied in general.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2003년도 춘계학술발표대회 개요집
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• pp.32-33
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• 2003

The evaluation of HAZ toughness and cold crack susceptibility of 90mm thickness API 2W Grade 50 steel has been made in accordance with API RP 2Z as preproduction qualification test to be certified as il steel supplier from Shell International E & P. It was shown that the steel has superior HAZ toughness; CTOD value for CGHAZ more than 1.5mm at -10$^{\circ}C$, CVN absorbed energy more than 150J at -60$^{\circ}C$. Additionally, no generation of cold cracks was observed at 0.7kJ/mm even without preheating condition. These excellent results are due to the extremely low hardenability in HAZ of the steel.

• 대기
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• 제29권4호
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• pp.463-480
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• 2019

This study classified heavy rain types from K-means clustering for the hourly relationship between rainfall intensity and cloud top height over the Korean peninsula, and then examined their statistical characteristics for the period of June~August 2013~2018. Total rainfall amount of warm-type events was 2.65 times larger than that of the cold-type, whereas the lightning frequency divided by total rainfall for the warm-type was only 46% of the cold-type. Typical cold-type cases exhibited high cloud top height around 16 km, large reflectivity in the upper layer, and frequent lightning flashes under convectively unstable condition. Phenomenally, the cold-type cases corresponded to cloud cluster or multi-cell thunderstorms. However, two warm-type cases related to Changma and typhoon were characterized by heavy rainfall due to long duration, relatively low cloud top height and upper-level reflectivity, and the absence of lightning under the convectively neutral and extremely humid conditions. This study further confirmed that the forecast skill of rainfall could be improved by applying correction factor with the overestimation for cold-type and underestimation for warm-type cases in the Local Data Assimilation and Prediction System (LDAPS) operational model (e.g., BIAS score was improved by 5%).

• 한국수산과학회지
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• 제30권6호
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• pp.997-1004
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• 1997

The effect of the oceanic condition on variations of the catches of Alaska pollack (Theragra chalcogramma) in the East Sea (the Japan Sea) is examined using monthly catches data of this fish and temperature data during 1972 to 1991. Since 1973 the catches of Alaska pollack have gradually increased, showing a peak in 1981, and then rapidly decreased after 1986. A significant negative correlation was found between variations of the catches and the temperature at 50 m depth offshore Mukho. In 1981, the year of the highest catches in the study period, the water mass in the Eastern Korean Coastal Sea of the East Sea was extremely cold, while the year of poor catch, 1979, was much warmer than the annual mean temperature. The results show that the temperature variations around the Eastern Korean Coastal Sea play an important role in the variations of the catches of Alaska pollack, implying that the effect of the Tsushima Warm Current is also very important.

• 농약과학회지
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• 제13권4호
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• pp.262-266
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• 2009

유채 근권으로 부터 분리된 고활성 근권균 Burkholderia pyrrocinia 13-1는 유채의 생육을 촉진 시키며 특히 저온조건에서의 식물 생육이 우수하다. 이 균주의 유채 처리는 저온조건에서 뿌리의 발근을 좋게 하며 지상부 생육도 다른 대조 균주처리 보다 우수하다. 근권미생물이 가지는 유용 기능 중 식물의 영양 흡수와 병 저항성에 관여하는 시드로포어의 생성, 항균활성과 토양 중 불용화 인산인 칼슘포스페이트를 가용화시켜 식물의 흡수를 돕는 용해 능력이 우수하였다. 이와 같은 특성은 식물의 생육을 촉진시키는 근권세균의 활성기작으로 식물생육 촉진용으로 유채재배에 적용할 수 있을 것으로 기대된다.

• 설비공학논문집
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• 제23권8호
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• pp.571-579
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• 2011

Heat pump systems for commercial building with variable refrigerant flow(VRF) are expanding a market due to high energy efficiency, lower maintenance cost and easy installation comparing with the conventional heat pump with the constant refrigerant flow. In general, heat pump systems degrade the energy efficiency in the extremely low temperature regions. In this study, VRF heat pump system with refrigerant heating is experimentally investigated to overcome the low heating performance in the extremely low temperature regions. VRF heat pump system with refrigerant heating is found out the sufficient heating performance in the -25 degree temperature condition comparing with the conventional heat pump system and is obtained more than 2,500 kPa high pressure in the evaporator at low temperature.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 춘계 학술논문 발표대회
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• pp.75-77
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• 2013

In this study, the characteristics of temperature history was evaluated for three hot wires with different capacity installed in slab concrete which are relatively thin. Results can be summarized as follows. First, for the case of material using 5W hot wire, all decreased to below zero at or around 24 hours. Similarly, the material using 20W hot wire decreased to 2℃ below zero at or around 80 hours but satisfied the accumulative temperature of 45° D·D at 7 days of material age. On the other hand, the case of 30W hot wire, the biggest capacity, showed the high temperature history of 5℃ in average at all areas except the corners. Thus, the target accumulative temperature was secured at or around the 3 days of material age. Considering the above, the initial damage by freezing can be prevented only if 20W or higher hot wires are used for the slabs at -10℃ of extremely low temperature environment.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1236-1240
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• 2004

Thermal vacuum test for satellites should be performed before launch to verify the feasibility of satellites' operation in a harsh space environment which is represented as an extremely cold temperature and vacuum condition. A large space simulator(${\Phi}8m{\times}L10m$) has been demanded to accomplish the thermal vacuum test for the huge satellites designed in compliance with the national space program of Korea. In this paper, the design and calculation of thermal shroud which is the core part of large space simulator were discussed. The characteristics of the large space simulator being constructed at Korea Aerospace Research Institute(KARI) were depicted.

• 한국주조공학회지
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• 제22권4호
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• pp.155-159
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• 2002

Magnesium alloys have high strength to weight ratio and are extremely attractive for applications in transport industry. Most of structural magnesium alloys are manufactured by die casting process. The tensile properties of AZ91HP magnesium alloy were investigated after die casting under various die casting conditions. After die casting by using cold chamber machine, the volume porosity of specimens was examined with density method. With the increase of the volume porosity of specimens, both the tensile strength and elongation were significantly decreased, however the 0.2% offset strength was almost independent of the amount of porosity. With the increase of crystal pressure from 500 to 900 bar during die casting, the volume porosity was decreased, which resulted in the increase of the tensile strength. The mould temperature within the range of $150{\sim}250^{\circ}C$ has not influenced the microstructure with the eutectic phase and tensile properties of specimens. The tensile strength was the highest at 90m/sec of gate speed.