• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 1995년도 추계학술발표회논문집(2)
• /
• pp.636-643
• /
• 1995

The accurate determination of the fuel-cladding gap conductance as functions of rod burnup and power level may be a key to the design and safety analysis of a reactor. The incorporation of a sophisticated gap conductance model into nuclear design code for computing thermal hydraulic feedback effect has not been implemented mainly because of computational inefficiency due to complicated behavior of gap conductance. To avoid the time-consuming iteration scheme, simplification of the gap conductance model is done for the current design model. The simplified model considers only the heat conductance contribution to the gap conductance. The simplification is made possible by direct consideration of the gas conductivity depending on the composition of constituent gases in the gap and the fuel-cladding gap size from computer simulation of representative power histories. The simplified gap conductance model is applied to the various fuel power histories and the predicted gap conductances are found to agree well with the results of the design model.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2011년도 정기 학술대회
• /
• pp.112-115
• /
• 2011

본 연구는 분자동역학 전산모사를 통하여 나일론 6 고분자재료 및 나이론 6 고분자재료를 기지재료로 사용하는 나노복합재에 대하여 인장하중을 부여하고, 인장에 의하여 발생하는 구조적 변화 및 물질의 구조적 특성과 열전도 특성 사이의 상관관계를 규명하였다. 나노복합재의 열전도특성을 변화시키는 주요 인자로는 나노입자, 인장에 의한 고분자 사슬의 배열 변화, 자유부피(free volume)의 변화이다. 고분자 사슬이 열전달 방향으로 배열될 경우 음양자(phonon)의 흐름을 가속화하여 열전도특성이 증가하며, 반면 자유부피의 증가는 음양자의 산란을 증가시켜 열전도특성이 저하된다. 따라서 서로 상반작용을 하는 두 인자가 복합적으로 작용하여 열전도 특성을 결정한다. 인장 하중이 부여됨에 따라 시스템의 열전도특성이 증가하며, 각 시스템의 증가 정도는 시스템의 구조적 특성에 따라 서로 다르다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2009년도 춘계학술대회 논문집
• /
• pp.1963-1969
• /
• 2009

This paper introduces method to estimate pollutant negative influence to polymer type insulator according to the international standard. To accomplish this goal, effective sample collecting method was surface was collected directly with the same dimension. Distilled Through this method pollute is easily and accurately collected. The second step is pollutant analysis. Several analyze item is selected such as quantity, conductivity, contact angle, Optical Microscope(OM), IR spectrometer(FT-IR), Equivalent Salt Deposit Density(ESDD), Thermal Analyzer(TA) and ICP-AES. The third step, best represent tunnel was selected considering location, length and natural surroundings. Also to consider the difference at inside the tunnel, several bracket insulators were selected along to the location. To make the result precise, above procedure was repeated several times at the same target. Finally relation among type of train, numbers of movement, surroundings, length will be considered in combination with the pollution. With this result pollute map for KORAIL could be accomplished and inspect period will be optimized case by case.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 1994년도 특별강연 및 춘계학술발표 개요집
• /
• pp.222-225
• /
• 1994

The weldability of aluminum is excel lent but weld metal is subject to include weld defects such as porosities, crack, incomplete penetration and incomplete fusion because of improper welding parameters. Especially, the porosities are main weld defects because the difference of hydrogen solubility change in melt ins and solidification state with temperature changing. Deformation of aluminum is larger than mi Id steel due to higher thermal conductivity. It is reported that porosities in deposited metal affect tensile strength and elongation. Therefore, the effect of groove angle on porosities and mechanical properties of weld metal were researched in this report where Al-5083 plate was used with 5356 filler metal that are excellent anti corrosion and strength.

• 한국막학회:학술대회논문집
• /
• 한국막학회 2004년도 춘계 총회 및 학술발표회
• /
• pp.57-60
• /
• 2004

Polymer electrolyte membranes have been studied widely in chloro-alkali electrolysis, cationic exchange resins, and fuel cell applications. Especially, sulfonated polyimide membranes have been suggested as a potential polymer electrolyte in PEMFC due to their excellent thermal stability and high proton conductivity.(omitted)

• 한국막학회:학술대회논문집
• /
• 한국막학회 2004년도 춘계 총회 및 학술발표회
• /
• pp.65-68
• /
• 2004

Proton-exchange membranes have attracted much attention in the past few decades due to their important application in fuel cell systems. The mainly used proton-exchange membranes are perfluoropolymers such as DuPont's Nafion$^{(R)}$ and Asahi Chemical's Aciplex$^{(R)}$ because of their high performance including high proton conductivity ＆ mechanical strength, and excellent thermal ＆ chemical stability.(omitted)ted)

• 한국태양에너지학회 논문집
• /
• 제23권4호
• /
• pp.63-70
• /
• 2003

It is very important to improve the insulation performance of curtain wall anchoring unit since it is composed of materials with high thermal conductivity, such as aluminium, steel and so on. This study aims to evaluate the heating energy performance and economical efficiency of various alternatives which are different in position and material of insulation. As results, alternative of inserting the urethane washer & pad and coating the anchoring unit with urethane foam can improve the heating energy performance and L.C.C(Life Cycle Cost) by 6.33% and 0.95%, respectively, as compared with the existing case.

• 한국태양에너지학회 논문집
• /
• 제36권3호
• /
• pp.87-94
• /
• 2016

Earth tube system can be installed in many ways. However, performance data on earth tube system is still insufficient. Therefore, in this study seven design parameters of earth tube systems were chosen such as underground earth tube length, depth, tube thermal conductivity, thickness, radius, soil conditions, and fan type. And the change effects in the values of the seven parameters on earth tube exit temperatures and heat transfer rate were examined through Energyplus simulations.

• 반도체디스플레이기술학회지
• /
• 제3권4호
• /
• pp.29-32
• /
• 2004

Fully depleted Silicon-on-Insulator (FD-SOI) devices lead to better electrical characteristics than bulk CMOS devices. However, the presence of a thin top silicon layer and a buried SiO2 layer causes self-heating due to the low thermal conductivity of the buried oxide. The electrical characteristics of FDSOI devices strongly depend on the path of heat dissipation. In this paper, we present a new three-dimensional (3-D) analysis technique for the self-heating effect of the finger-type and bar-type transistors. The 3-D analysis results show that the drain current of the finger-type transistor is 14.7% smaller than that of the bar-type transistor due to the 3-D self-heating effect. We have learned that the rate of current degradation increases significantly when the width of a transistor is smaller that a critical value in a finger-type layout. The current degradation fro the 3-D structures of the finger-type and bar-type transistors is investigated and the design issues are also discussed.

• 한국방재학회:학술대회논문집
• /
• 한국방재학회 2010년도 정기 학술발표대회
• /
• pp.91.1-91.1
• /
• 2010

본 연구에서는 수직 밀폐형 지중 열교환기를 현장 시험시공하고 현장 열응답 시험을 수행하여 보어홀과 지반의 유효열전도도를 측정하였다. 뒤채움용 그라우트재는 벤토나이트와 시멘트가 고려되었으며 첨가제로는 천연규사와 흑연을 사용하고, 지중 열교환기 파이프 단면은 일반적으로 시공되는 U-loop 파이프 단면과 파이프 사이의 열간섭 효과를 최소화 한 3공형 파이프 단면이 착용되었다. 시멘트-천연규사 그라우트재가 벤토나이트-천연규사 그라우트재 보다 큰 유효열전도도를 보이고 흑연을 첨가한 그라우트는 시멘트와 벤토나이트 모두에서 천연규사만 첨가하였을 때 보다 유효열전도도가 높게 나타났다. 3공형 파이프 단면의 경우 단면에 따른 영향을 비교하기 위해 그라우트는 시멘트-천연규사와 벤토나이트-천연규사를 사용하였으며 유효 열전도도 측정결과 각각 3.65 W/mK, 3.40 W/mK으로 일반 U-loop 파이프 단면을 사용하였을 때 보다 높게 나타났다.