• 한국결정학회지
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• 제14권1호
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• pp.7-12
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• 2003

화합물, SrAl₂(BO₃)₂O는 매우 효과적으로 열적 수축성을 나타내는 격자를 가지고 있다. 우리는 세라믹 시험편의 열팽창 계수측정법과 X-선 회절 분광법을 이용하여 제한된 온도 범위에서 열적 수축을 각각 측정하였다. 알루미늄 보레이트 화합물에 있어서, 열적 수축성은 23∼215℃ 온도 범위에서 c 축에 대한 열팽창 계수 -1.64×10/sup -4/ Å/℃를 보였으며, 20㎜ 세라믹 시험편에 대한 길이의 변화측정 결과는 110∼170℃ 온도 범위에서 최대 -1.75㎛까지 수축하였다.

• International Journal of Concrete Structures and Materials
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• 제18권3E호
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• pp.145-150
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• 2006

An experiment with the objective of providing guidelines for joint depth determination and timing of contraction joint sawcutting to avert uncontrolled cement concrete pavement cracking has been conducted. Theoretical analysis and laboratory tests were performed to help in understanding and analyzing the field observation. Using two-dimensional elastic fracture mechanics, the influence of several parameters on crack propagation was delineated by a parametric study, involving initial notch ratio, joint spacing, Young's modulus and thermal expansion coefficient of concrete, temperature gradient, and modulus of subgrade reaction. Bimaterials made of rock plus cement mortar and rock plus polymer mortar were applied to the concrete in a field test section, and they were subjected to fracture tests. These tests have shown that fracture mechanics is a powerful tool not only in judging the quality of the jointed cement concrete pavement but also in providing a criterion for crack propagation and delamination. Based on fracture mechanics, a method is proposed to determine the joint depth, sawcut timing, and spacing of the jointed cement concrete pavement. This method has successfully been applied to a test section in Seohaean expressway. This study also summarizes the research results obtained from a field test for jointed plain concrete pavement, which was also carried out on the Seohaean expressway.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전기설비전문위원
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• pp.199-202
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• 2008

In this paper, we studied a accuracy for CT using elastic epoxy. According to industry development, the quality where also the electric material is various is demanded. Insulation material is widely used because epoxy is superior to electrical and mechanical property. Until now, the possibility where the crack will occur is high because epoxy used to electrical products had high hardness. If thermal expansion is different of two material, contraction of epoxy heavily transformed turns ratio of CT Elastic epoxy absorbed in expansion and contraction of substance material by temperature. So we could design more exacted CT We had elastic test of elastic epoxy and made CT using elastic epoxy. At the result, We obtained turns ratio of within 4% superior to existing CT.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.150.2-150.2
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• 2011

Unlike non-ionic clathrate hydrates stably formed by van der Waals interaction between a guest molecule and a surrounding host framework, ionic clathrate hydrates are stabilized by ionic interaction between an ionic guest molecule and the host water-framework. Here, we firstly described the stable entrapment of the superoxide ions in ${\gamma}$-irradiated $Me_4NOH+O_2$ hydrate. Owing to peculiar direct guest-guest ionic interaction, the lattice structure of ${\gamma}$-irradiated $Me_4NOH+O_2$ hydrate shows significant change of lattice contraction behavior even at relatively high temperature(120K). Particularly, we note that ionic-induced dimensional change is much greater than thermal-induced change. Such findings are expected to provide useful information for a better understanding of unrevealed nature of clathrate hydrate fields.

• KSTLE International Journal
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• 제1권2호
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• pp.76-82
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• 2000

Turbulence in journal bearing operation is examined and the thermal variability is studied for isothermal, convective and adiabatic conditions on the walls under aligned and misaligned conditions. Also, the effects of a contraction ratio at the cavitation region and the mixing between re-circulating oil and inlet oil on the fluid field of oil film are included. An algorithm for the solution of the coupled turbulent Reynolds and energy equations is used to examine the effects of the various factors. Heat convection is found to play only a small role in determining friction and load under no mixing condition. However, under realistic mixing condition, the heat convection cannot be ignored. The wall temperature and heat transfer have been found to be of secondary important factors to the mixing effectiveness at the groove and the final mixture temperature.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기물성,응용부문
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• pp.197-199
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• 2004

In this paper, we studied a accuracy for CT using elastic epoxy. According to industry development, the quality where also the electric material is various is demanded. Insulation material is widely used because epoxy is superior to electrical and mechanical property. Until now, the possibility where the crack will occur is high because epoxy used to electrical products had high hardness. If thermal expansion is different of two material, contraction of epoxy heavily transformed turns ratio of CT. Elastic epoxy absorbed in expansion and contraction of substance material by temperature. So we could design more exacted CT. We had elastic test of elastic epoxy and made CT using elastic epoxy. At the result, We obtained turns ratio of within 4% superior to existing CT.

• 한국도로학회논문집
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• 제4권3호
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• pp.35-42
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• 2002

본 연구는 동절기에 많이 발생하는 포장의 저온균열에 대한 폴리머 개질 아스팔트 혼합물의 저항 특성을 알아보기 위하여 수행하였다. 저온에서의 간접인장강도를 측정 분석한 결과 혼합물들이 $-10^{\circ}C의 저온 대에서 최대 인장강도를 나타냈다. 최대 인장강도를 보이는 온도 이하에서는 시차열 응력이 인장강도 이상으로 발생하여 내부에 손상이 발생하기 때문에 나타나는 인장강도 저하현상을 ITS 시험으로 증명하여 보였다. 저온의 시험 결과는 폴리머 개질 아스팔트 혼합물이 일반 아스팔트 혼합물에 비하여 보다 낮은 온도에서까지도 강도가 높게 나타나 폴리머 개질에 따른 효과를 보였으며, 바인더가 저온균열에 대한 저항에 큰 영향을 미치는 것으로 나타났다. 따라서 추운 지역에서는 저온균열을 예방하기 위하여 폴리머 개질 아스팔트의 사용이 추천된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.238-241
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• 2006

The needs for strengthening and rehabilitation of the concrete bridges are a growing concern in many countries and has been emphasized in various researches and papers. Traditional external post-tensioning method using either steel bars or tendons is commonly used as a strengthening method. However, the method has some disadvantages such as stress concentration at the anchorages. Multi-stepwise thermal prestressing method is a newly proposed method for strengthening and rehabilitation of concrete girder bridges. Founded on a simple concept of thermal expansion and contraction of steel, the method is a hybrid method of external post-tensioning and steel plate bonding, combining the merits of two methods. In this paper, basic concepts on strengthening and rehabilitation of concrete girder are presented and an illustrative experiment is introduced.

• 대한가정학회지
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• 제40권5호
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• pp.15-24
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• 2002

The following research conclusions were made, relative to the experiments of the textiles of fire fighters Protective Clothing. 1. When the body protection efficiency such as the thickness, the strength and heat resistance are considered, Nomex(N) is tuned out the best outer shelf, Gore-tex(KG) the best moisture barrier, and Wool-felt(WC) the best thermal barrier. 2. In the hygienic and sanitary efficiency also, N is turned out the best outer shelf, KG the best moisture barrier, and WC the best thermal barrier in its degree of water resistance, water vapour permeability, and air permeability. 3. In the washing and maintenance efficiency, too. N is turned out the best outer shell, KG the best moisture barrier, and WC the best thermal barrier, being considered the material's rate of contraction, the changing rate of frame resistance, water resistance, and water vapour permeability. 4. When considered the frame resistance against the reflection tape and reflection efficiency, O is the best material for it marks the highest score in the frame resistance and reflective effect.

• 한국디지털건축인테리어학회논문집
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• 제11권1호
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• pp.33-42
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• 2011

As the development of construction technology and new materials, building requirements has been varied gadually. Comfortable environment and serviceability of production activity and energy conservation are being dealt with very seriously. Recently localization of engineering technology of Power Plant, however, construction materials and domestic technology are being developed forcingly. According to above topics this thes is going to study roof waterproofing, thermal insulation and evaluate adiabatic performance and evaluation of properties of waterproofing materials and energy conservation. The results of studying and evaluating of roof waterproofing, thermal insulation and adiabatic performance of Power Plant are as follows. 1. Sheet waterproofing method is better than that of asphalt waterproofing method in that adaptability of wearhertight, thermal resistant, contraction and expansion. 2. It is required to replace polyurethane or ethylene used as thermal insulation with rock wool which is noncombustible materials. 3. It is recommended to usd outer insulation method than inner insulation method due to superioty of outer insulation method. Efficiency of insulation materials used in power plant is generally good except perlite mortar used in the power plant(YGN 1-2, GRI 1-2).