• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.380-383
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• 2006

수소는 미래의 청정에너지원이다. 수소를 생산하는 효과적인 방법으로는 탄소계촉매를 이용하여 부탄을 분해하는 것이다. 촉매는 카본블랙이 사용되었으며, $500{\sim}1100^{\circ}C$의 온도 범위에서 열분해 반응과 촉매분해반응이 수행되었다. 열분해의 경우 온도가 증가함에 따라 전화율이 증가하여 $800^{\circ}C$에서 98.9%로 부탄이 거의 분해되었으며, $900^{\circ}C$ 이상의 온도에서는 전화율이 100%까지 도달하였다. 부탄 분해반응에서 기대되는 생성물은 메탄, 에틸렌, 에탄, 프로필렌, 프로판 등이다. $1000^{\circ}C$이상의 온도에서는 부탄 촉매 분해반응에서 거의 대부분 수소와 메탄만이 관찰되었다. 특히 $500-1100^{\circ}C$까지 온도가 증가하였을 때 수소의 생성율은 꾸준히 증가하는 것으로 확인되었고 촉매분해반응이 촉매를 사용하지 않은 열분해반응보다 온도가 증가함에 따라 수소의 선택도를 더욱 향상시켜 보다 많은 수소가 생성되었으며, 반응성 실험이 진행되는 동안 촉매의 비활성화는 관찰되지 않았다. 반응전후의 촉매의 특성을 분석하기 위해 TEM 및 SEM 분석을 하였다. 반응전의 촉매는 매끈한 모양이었으나 $1000-1100^{\circ}C$에서 반응후에는 표면에 돌기모양을 형성하는 것을 관찰할 수 있었다.

• Journal of the Korea Computer Industry Society
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• v.9 no.3
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• pp.99-104
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• 2008

The thermal stresses due to hydration heat in massive concrete structures are affected by ambient temperature and placing concrete temperature. It is needed to predict the thermal stresses considering ambient temperature and placing concrete temperature. In this study, hydration heat analyses of coping were carried out. After the maximum tensile stress was occurred at 2,75 days the crack index was increased. Therefore the possibility of crack occurrence was rare. The possibility of crack occurrence can be reduced by placing concrete temperature drop. Therefore some method to drop the placing concrete temperature may be effective to reduce the possibility of crack occurrence.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.243.1-243.1
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• 2013

본 연구에서는 산소 분압과 열처리 온도에 따른 ITZO 박막 트랜지스터의 전기적 특성 향상을 목적으로 실험을 진행하였다. 1) ITZO 박막 증착 시 산소 분압 가변($O_2/(Ar+O_2)$ 30~40%), 열처리 온도 고정($350^{\circ}C$)과 2) ITZO 박막 증착 시 산소 분압 고정(30%), 열처리 온도($200{\sim}400^{\circ}C$)를 가변하여 실험을 진행하였다. 두 실험 모두 특성향상을 위해 산소 분위기에서 열처리를 진행하였다. 산소의 분압이 증가할수록 산소 빈자리를 채우면서 전자 농도가 감소하여 채널 전도 효과가 줄어들면서 Hump 현상이 발생하였고, 스윙이 증가, 문턱 전압이 음의 방향으로 이동하였다. 이에 $O_2/(Ar+O_2)$)의 30%에서 30%일때, 문턱전압은 1.98 V, 전계 효과 이동도는 28.97 $cm2/V{\cdot}s$, sub-threshold swing은 280 mv/dec, on-off 비율은 ~107로 가장 우수한 전기적 특성을 보였다. 또한 열처리 온도 가변 시 $400^{\circ}C$에서 전계 효과 이동도는 28.97 $cm^2/V{\cdot}s$로 $200^{\circ}C$의 전계 효과 이동도는 11.59 $cm^2/V{\cdot}s$에 비해 약 3배 증가하였고, 소자의 스위칭 척도인 sub-threshold swing은 약 180 mv/dec 감소하였다. 문턱 전압은 0.97V, on-off ratio는 약 107을 보였다. 동일한 산소 분압의 분위기에서 $400^{\circ}C$ 열처리 시 가장 우수한 전기적 특성을 보였고, 저온 공정으로 인한 플렉서블 디스플레이 투명 디스플레이 적용 가능성을 확인하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.5
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• pp.1706-1716
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• 1991

본 연구에서는 혼합대류하는 연직원통휜 열전달에 미치는 복사효과에 Rossel- and 근사해법을 도입한 층류 경계층방정식과 휜 전도방정식을 동시에 해석하여 복사 -전도매개변수(radiation-conduction parameter) M, 대류-전도 매개변수(convectionc- onduction parameter) N$_{c}$, 부력매개변수(buoyancy force parameter) R$_{i}$ 그 리고 횡곡률 매개변수(transverse curvature parameter) .lambda.를 계산 파라미터로 하여 휜 최적설계의 기본이 되는 총열전단률, 무차원 국소등가열전달계수, 무차원 국소열플 럭스 및 휜온도분포를 계산할 수 있는 일반성있는 algorithm을 개발하고 휜 성능에 관 한 결과들을 제공함으로써, 좀 더 완전한 복사 열플럭스를 도입한, 다음 연구를 위한 범용의 기초자료를 얻는데 본 연구의 목적이 있다.

• Korean Journal of Materials Research
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• v.7 no.7
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• pp.547-558
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• 1997

Pb(Mg$_{1}$3/Nb$_{2}$3)O$_{3}$[PMN]-PbTiO$_{3}$[PT]계 고용체의 상경계조성(MPB)영역에 대해 La을 첨가하여 변성시킨 La변성 (1-x)PMN-xPT(x=0.35) 고용체를 만들어 온도-유전율 특성, 전계유기 분극특성 및 변위특성을 조사하였다. PMN-PT의 상경영역의 조성인 x=0.35에 대해 La함량을 0-10at%까지 변화시켰다. PMN-PT계 고용체에서 PT 의 함량이 증가함에 따라 전계유기변위 및 히스테리시스 특성이 모두 증가하였다. 전계유기변위 값 $\varepsilon$ 는 능면정과 정방정의 공존영역인 MPB(x=0.35)조성에서 가장 높은 값($\varepsilon$ = 2 x $10^{-3}$)을 보여 주었다. MPB조성에 대해 La을 첨가한 계의 전계유기변위를 조사한 결과 La의 첨가량이 적을 때 (La=0-5at%)는 La의 함량이 증가함에 따라 히스테리시스 특성이 감소하였고 $\varepsilon$ 은 증가하여 고성능의 액튜에이터 재료에 적합한 조성물로 기대된다.

• Journal of The Korean Society of Grassland and Forage Science
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• v.12 no.2
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• pp.77-84
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• 1992

This experiment was designed to gain information on factors affecting stubble death of orchardgrass (Dactylis glomerata L.) during the first rainy season. According to the experimental plan, the effects of sowing methods, drainages and cutting dates on the stubble carbohydrate content of orchardgrass, available soil moisture content of experimental plots, temperatures at the ground level and in the soil, and relative light intensity and humidity at the base of orchardgrass canopy were measured during the rainy season. The carbohydrate content of orchardgrass was sharply decreased to 2.9 % at 3rd day after cutting in the plots cut before rainy season and a gradural recovery was noted following the sharp reduction, but in the plots cut after rainy season, orchardgrass showed 5.5% of carbohydrate content before cutting and 3.0% at the 3rd day after cutting. The same pattern in both carbohydrate reduction and recovery was found between two cutting treatments. The available soil moisture content in the plots cut before rainy season was slightly higher than that in the plots cut after rainy season. But after the rainy season, the available soil moisture content in the plots cut after rainy season was higher than that in the plots cut before rainy season. Soil temperature at lOcm depths in the plots cut before rainy season was higher than that in the plots cut after rainy season. Daily maximum air temperature at the ground level in the plots cut before rainy season was higher than that in the plots cut after rainy season and changeable. Relative humidity at the ground level was below 70% in the plots cut before rainy season, but 75 to 90 % was observed in the plots cut after rainy season. Relative light intensity at the ground level in the plots cut before rainy season was much higher, recorded 50 to 90 %, than that in the plots cut after rainy season showing less than 10%. The results of this study suggest that the stubble death of orchardgrass during the rainy season is due to plant diseases influenced by a decrease of light penetration and increase of relative humidity at the base of the grass canopy.

• Journal of the Korean Ceramic Society
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• v.41 no.8
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• pp.593-598
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• 2004

To make the all-solid-state lithium thin film battery having less than 1 fm in thickness, LiCoO$_2$ thin films were deposited on Pt/TiO$_2$/SiO$_2$/Si substrate as a function of Li/Co mole ratio and the deposition temperature by Pulsed Laser Deposition (PLD). Especially, LiCoO$_2$ thin films deposited at 50$0^{\circ}C$ with target of Li/Co=1.2 mole ratio show an initial discharge capacity of 53 $\mu$Ah/cm$^2$-$\mu$m and capacity retention of 67.6％. The microstructural and electrochemical properies of (Li, La)TiO3 thin films grown on LiCoO$_2$Pt/TiO$_2$/SiO$_2$/Si structures by Pulsed Laser Deposition (PLD) were investigated at various deposition temperatures. The thin films grown at 10$0^{\circ}C$ show an initial discharge capacity of approximately 51 $\mu$Ah/cm$^2$-$\mu$m and moreover show excellent discharge capacity retention of 90％ after 100 cycles. An amorphous (Li, La)TiO$_3$ solid electrolyte is possible for application to solid electrolyte for all-solid-state lithium thin film battery below 1 $\mu$m.

• Korean journal of food and cookery science
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• v.14 no.2
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• pp.182-187
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• 1998

The changes in weight, reducing sugar content, sugar composition and enzyme activities (${\beta}$-amylase and invertase) of sweet potato were studied with three kinds of cooking methods, microwave oven, gas oven, and steaming. The weights of sweet potato cooked by microwave oven and gas oven were decreased with increasing cooking time, whereas that of steaming was increased with cooking time. Reducing sugar content of sweet potato cooked by microwave oven was increased till 40 seconds, but decreased thereafter. In the cooking methods using gas oven and steaming, reducing sugar content were increased with cooking time. And reducing sugar content were 334.60 mg/g and 381.29 mg/g, respectively at 100$^{\circ}C$ of cold point in sweet potato cooked by gas oven and steaming. Raw sweet potato consisted of fructose (1.56 mg/g), glucose (1.79 mg/g), sucrose (5.58 mg/g), and maltose (2.22 mg/g). The contents of fructose, glucose, and sucrose were decreased during cooking process. But maltose content was increased with cooking time. Especially, maltose contents were 24.81 mg/g and 28.10 mg/g at 100$^{\circ}C$ of cold point in sweet potato cooked by gas oven and steaming. The activities of ${\beta}$-amylase and invertase were decreased with cooking time. Microwave oven-cooked sweet potato did not show on invertase activity.

• Journal of the Society of Naval Architects of Korea
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• v.39 no.2
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• pp.52-60
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• 2002

Line heating is a forming process which makes the curved surface with the residual strain created by applying heat source of high temperature to steel plate. in order to control the residual strain, it is necessary to understand not only conductive heat transfer between heat source and steel plate, but also temperature distribution of steel plate. In this paper we attempted to analyze is temperature distribution of steel plate by simplifying a line heating process to collision-effusive flux of high temperature and high velocity, and conductive heat transfer phenomenon. To analyze this, combustion in the torch is simplified to collision effusive phenomenon before analyzing turbulent heat flux. The distribution of temperature field between the torch and steel plate is computed through turbulent heat flux analysis, and the convective heat transfer coefficient between effusive flux and steel plate is calculated using approximate empirical Nusselt formula. The velocity of heat flux into steel plate is computed using the temperature distribution and convective heat transfer coefficient, and temperature field in the steel plate is obtained through conductive heat transfer analysis in which the traction is induced by velocity of heat flux. In this study, Finite Element Method is used to accomplish turbulent heat flux analysis and conductive heat transfer analysis. FEA results are compared with empirical data to verify results.

• Journal of Oral Medicine and Pain
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• v.30 no.4
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• pp.401-410
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• 2005

The purpose of this study was to assess the effect of heat therapy on cutaneous blood flow and skin temperature at pre-auricular region. Moist heat therapy and ultrasound therapy were applied to 20 healthy subjects(male: 10, female: 10). Cutaneous blood flow and skin temperature before and after heat therapy were measured with laser doppler flowmetry and thermocouple. The results were as follows ; 1. Cutaneous blood flow and skin temperature were significantly increased after moist heat therapy and ultrasound therapy. 2. In application of moist heat therapy, cutaneous blood flow and skin temperature were more increased and maintained longer than in ultrasound therapy. 3. Before heat therapy, cutaneous blood flow and skin temperature were higher in male. 4. There was no significant gender difference in changes of cutaneous blood flow and skin temperature after heat therapy. In conclusion, both moist heat therapy and ultrasound therapy increased cutaneous blood flow and skin temperature significantly, and moist heat therapy was more effective to increase cutaneous blood flow and skin temperature and to maintain increased cutaneous blood flow and skin temperature. There was no significant gender difference in the effect of heat therapy on cutaneous blood flow and skin temperature.