• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문발표회
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• pp.77-82
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• 2003

The purpose of this study is development of technique to use cementitious powder as recycle cement produced from deteriorated Concrete waste which has a large quantity of calcium carbonate. Therefore, after having theoretical consideration based on the properties of hish-heated concrete and concerning about neutralization of Concrete, we analysis chemical properties of ingredients of cementitious powder After making origin cement paste, then processing the accelerated carbonation, we consider the properties of hydration and chemical properties of cementitious powder under various temperature conditions As a result of the thermal analysis, the CacO3 content of cementitious powder would affect decision of heat temperature to recover its hydrated ability because CacO3 content is increased when neutraliTation is preBlessed. And as a result of XRD analysis. in case of origin powder of non-neutralized paste, CaO peak is found at $700^{\circ}C$. but, heat temperature to generate CaO would increase when the content of neutralized ingredients is increased. Finally, recycle cement heated at $700^{\circ}C$ shows the best compressive strength when the content of neutralized ingredients in recycle cement is less then 50%. However, it would be quite difficult to manage quality of recycle cement according to recycling points of various concrete waste.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기물성,응용부문
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• pp.24-25
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• 2006

In this paper, ZnO thin films were prepared on p-Si(100) by RF magnetron sputtering. Before the depostion, the substrates were pre-heated to 500, 400, 300, $200^{\circ}C$ or not. During the deposition, the substrates were cooled down naturally or kept and then the films were investigated by XRD(X-ray diffraction) and SEM (scanning micro scope). It is showed the most outstanding result that the film was prepared on the substrate were cooled from $400^{\circ}C$. When the substrate was cooled from a certain temperature during deposition, it could be improve the c-axis orientation and useful for application of SAW(surface acoustic wave) filter and FBAR(film bulk acoustic wave resonator) device.

• 한국연소학회지
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• 제19권2호
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• pp.1-7
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• 2014

In this study, the variation of the flow field in Hydro-reactive engine combustor was numerically studied through 2-dimensional axisymmetric model with aluminum and heated water vapor. For calculating all velocity fields, compressible Navier-Stokes equation was used with Pre-conditioning. AUSM+up(p) method was used to exactly calculate mass flow in the control volume. As using SST model that is a turbulent model, the result had high accuracy for free stream and the flow near the wall. The effects of the temperature, variation of the flow field and distribution of chemical products on inject angle of heated water vapor were studied.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 디스플레이 광소자분야
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• pp.155-159
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• 2003

The preparation and luminescence characterization of yttrium oxide doped with trivalent europium phosphors by sol-gel method have been investigated. Aqueous metal nitrate solution was mixed with EDTA which was chosen by the most suitable material of sol-gel formation one of appled various chelating agents. we noticed that the samples when are heated with EDTA at a temperature of $100^{\circ}C$ for 1hrs, produced brownish and crisp powders due to condensation reaction on decomposition, dehydration and formation of sol-gel. Hence, when the powder pre-heated was then heated at $1200^{\circ}C$ for 3hrs in atmosphere, the luminescence characterization of resultant $Y_{2}O_{3}:Eu^{3+}$ phosphor was enhanced upto maximum 30% significantly than conventional method through increasing porous region and decreasing particle sizes.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 디스플레이 광소자분야
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• pp.151-154
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• 2003

The synthesis and luminescent properties of trivalent europium activated gadolinium oxide red phosphors by sol-gel process have been investigated. Aqueous metal nitrate solution was mixed with EDTA which was chosen by the most suitable material of sol-gel formation as chelating agents. We noticed that the samples when are heated with EDTA at a temperature of $100^{\circ}C$ for lhrs, produced brownish and crisp powders due to condensation reaction on decomposition, dehydration and formation of sol-gel. Hence, when the powder pre-heated at about $100^{\circ}C$ was then heated at $1200^{\circ}C$ for 3hrs in atmosphere, the luminescence properties of resultant $Gd_{2}O_{3}:Eu^{3+}$ phosphor was measured by SEM, FT-IT and brightness intensity was shown 20% higher than those prepared by conventional method and by other chelating agent.

• Design & Manufacturing
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• 제11권1호
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• pp.7-13
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• 2017

The aim of this study is to develop the dies oven for energy-saving during the pre-heated process of extrusion dies. Applying high-efficiency near-infrared heater, single cell type dies oven was developed as a substitute for traditional chest type oven. Therefore the dies is individually heated uniformly to operation temperature so rapidly. By using the developed dies oven, electric-energy consumption of preheating extrusion dies reduced up to 30% and the waiting time in the oven also minimized up to 90min. In addition, the results have shown that it is possible to accurately control the dies temperature for improving the quality of extruded profile and to minimize die bearing oxidation and nitride layer degradation responsible for surface defects on the profile and shorter die life.

• 한국연소학회지
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• 제15권4호
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• pp.1-8
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• 2010

Mild combustion is considered as a promising combustion technology for energy saving and low emission of combustion product gases. In this paper, the controllability of reaction region in mild combustion is examined by using co-axial air nozzle. For this purpose, numerical approach is carried out. Propane is considered for fuel and air is considered for oxidizer and the temperature of air is assumed 900K slightly higher than auto ignition temperature of propane. But unlike main air, the atmospheric condition of co-axial air is considered. Various cases are conducted to verify the characteristics of Co-Axial air burner configuration. The use of coaxial air can affect reaction region. These modification help the mixing between fuel and oxidizer. Then, reaction region is reduced compare to normal burner configuration. The enhancement of main air momentum also affects on temperature uniformity and reaction region. The eddy dissipation concept turbulence/chemistry interaction model is used with two step of global chemical reaction model.

• Journal of Advanced Marine Engineering and Technology
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• 제39권1호
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• pp.81-85
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• 2015

본 연구에서는 Poly (3-hexylthiophene-2,5-diyl) (P3HT):[6,6]-Phenyl C61 butyric acid methyl ester (PCBM)과 GaN를 이용하여 유무기 하이브리드 광전변환소자를 제작함에 있어서, P3HT:PCBM 활성층의 열처리가 소자의 단락전류밀도에 미치는 영향을 알아보았으며 이때 유기물의 농도와 혼합비율을 달리 하였다. 유기물 각각의 층을 코팅하여 층을 만들 때마다 열처리 한 경우, 즉 pre-annealing샘플과 pre-annealing 과정을 거쳐 제작된 소자 전체를 한 번 더 열처리하여 즉 post-annealing까지 행한 샘플을 비교하였다. 그 결과 post-annealing한 샘플이 더 높은 단락전류밀도의 값을 가졌고 이때 P3HT와 PCBM은 1wt%와 1:1 혼합비율에서 좋은 열처리 효과를 나타내었다.

• 한국식품과학회지
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• 제31권6호
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• pp.1583-1588
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• 1999

마늘의 향미를 조절하기 위하여 박피하지 않은 마늘쪽을 $60^{\circ}C{\sim}90^{\circ}C$의 범위에서 30분간 예열처리한 경우와 전자레인지로 10초간 가열한 경우에 마늘의 향미성분변화를 조사한 결과는 다음과 같다. 마늘의 향기성분은 예열처리 온도가 상승함에 따라 감소하였고, $70^{\circ}C,\;80^{\circ}C$ 및 $90^{\circ}C$에서 30분간 예열처리하면 대조구에 비하여 각각 20%, 31% 및 49% 감소하였다. 전자레인지로 10초간 가열한 경우에는 열풍건조기에서 $70^{\circ}C{\sim}80^{\circ}C$에서 가열한 것과 유사한 경향을 보였다. 열풍건조기로 예열처리하면 glucose, fructose 및 fructooligosaccharide가 감소하였으며, 이런 감소는 온도가 높을수록 컸으며 fructooligosaccharide 보다는 단당류인 glucose와 fructose에서 더욱 컸다. 전자레인지로 가열처리한 경우에는 열풍건조기로 예열처리한 경우에 비하여 유리당의 변화가 현저히 적었다. Alliin의 분해산물로 알려진 pyruvic acid는 예열처리 온도가 증가할수록 감소하는 경향을 나타내었고, 그 밖의 유기산은 유의적 변화가 없었다. 마늘의 주요 아미노산인 arginine은 열풍에 의한 예열처리시 감소하였으나 전자레인지로 가열한 경우에는 감소하지 않았고, glutamic acid와 tyrosine은 모든 처리구에서 감소하였다.

• Structural Engineering and Mechanics
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• 제57권3호
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• pp.543-567
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• 2016

This study attempts to address the buckling and free vibration characteristics of an isotropic cylindrical panel subjected to non-uniform temperature rise using numerical approach. Finite element analysis has been used in the present study. The approach involves three parts, in the first part non-uniform temperature field is obtained using heat transfer analysis, in the second part, the stress field is computed under the thermal load using static condition and, the last part, the buckling and pre-stressed modal analysis are carried out to compute critical buckling temperature as well as natural frequencies and associated mode shapes. In the present study, the effect of non-uniform temperature field, heat sink temperatures and in-plane boundary constraints are considered. The relation between buckling temperature under uniform and non-uniform temperature fields has been established. Results revealed that decrease (Case (ii)) type temperature variation field influences the fundamental buckling mode shape significantly. Further, it is observed that natural frequencies under free vibration state, decreases as temperature increases. However, the reduction is significantly higher for the lowest natural frequency. It is also found that, with an increase in temperature, nodal and anti-nodal positions of free vibration mode shapes is shifting towards the location where the intensity of the heat source is high and structural stiffness is low.