• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
• /
• pp.497-500
• /
• 2000

This paper describes the procedures to estimate for the design thermal loads on prestressed concrete box girder bridges on th basis of the extreme analysis of the temperature data obtained from long-term thermal analyses. Long-term thermal analyses using the environmental data for three years were conducted, and the extreme distributions of th thermal loads are then determined by the tail-equivalence method, and the thermal loads corresponding to selected return period are calculated. Finally, the results are compared to the specifications suggested in a current design code for thermal loads.

• Journal of Astronomy and Space Sciences
• /
• 제23권1호
• /
• pp.39-54
• /
• 2006

HAUSAT-2는 한국항공대학교 우주시스템 연구실에서 개발하고 있는 25kg급의 소형위성 이다. 위성의 시스템과 부품의 안정적인 작동을 확인하기 위하여 위성의 시스템과 박스모듈 그리고 전장보드 수준에서 열해석을 수행하였다. 시스템과 박스-레벨 열해석에 적용한 열 모델링은 HAUSAT-2 구조-열 모델의 열진공/균형 시험을 통하여 검증 및 보정되었다. 본 연구에서는 주요 소자를 직접 모델링하는 방법의 보드-레벨 열해석 방법론을 제안하고, 그에 따른 결과 분석 및 타당성을 제시하였다.

• 전기학회논문지
• /
• 제60권12호
• /
• pp.2311-2317
• /
• 2011

In this paper, we study the temperature change of a ${\mu}$-bolometer focal plane array with a capacitive transimpedance amplifier bias cancellation circuit. Thermal analysis is essential to understand the performance of a ${\mu}$-bolometer focal plane array, and to improve the temperature stability of a focal plane array characteristics. In this study, the thermal analyses of a ${\mu}$-bolometer and its two reference detectors are carried out as a function of time. The analyses are done with the $30{\mu}m$ pitch $320{\times}240$ focal plane array operating of 60 Hz frame rate and having a columnwise readout. From the results, the temperature increase of a ${\mu}$-bolometer in FPA by an incident IR is estimated as $0.689^{\circ}C$, while the temperature increase by a pulsed bias as $7.1^{\circ}C$, which is about 10 times larger than by IR. The temperature increase of a reference detector by a train of bias pulses may be increased much higher than that of an active ${\mu}$-bolometer. The suppression of temperature increase in a reference bolometer can be done by increasing the thermal conductivity of the reference bolometer, in which the selection of thermal conductivity also determines the range of CTIA output voltage.

• 기술사
• /
• 제32권6호
• /
• pp.60-67
• /
• 1999

299 chemical analyses are used to study the characteristics of mineral and thermal waters in South Korea. Even though the concentration of chemical components in thermal waters are generally very low, mineral waters having components more than 1,000 ppm of dissolved total solid(TDS) are reached up to 19% total analyses data, In Germany, Japan or some other countries, mineral and thermal waters are detined not only by water temperature, but also by chemical components. The principle of Law in Japan in also almost same with the German regulations. However, the Law for thermal spring In Korea permit thermal water to be qualifiled only by water temperature. For including chemical characters into the regulations or Law of thermal spring, the limit values of TDS and other 9 micro components related to mineral and thermal waters was selected through this study.

• 기술사
• /
• 제33권1호
• /
• pp.75-82
• /
• 2000

299 chemical analyses are used to study the characteristics of mineral and thermal waters in South Korea. Even though the concentration of chemical components in thermal waters are generally very low, mineral waters having components more than 1,000 ppm of dissolved total solid(TDS) are reached up to 1975 of total analyses data, In Germany, Japan or some other countries, mineral and thermal waters are defined not only by water temperature, but also by chemical components. The principle of Law in Japan is also almost same with the German regulations. However, the Law for thermal spring In Korea permit thermal water to be qualifiled only by water temperature. For including chemical characters into the regulations or Law of thermal spring, the limit values of TDS and other 9 micro components related to mineral and thermal waters was selected through this study.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2005년도 추계학술발표대회 논문집
• /
• pp.161-164
• /
• 2005

This paper finds the optimal staking sequence of the satellite composite structures to minimize severe thermal deformations during their orbital operation using GAs and finite element analyses. Then, the optimal design is reinforced to endure the launch loads like high inertia and vibratory loads that are, usually, smaller than orbital loads induced by space environments. The thermal deformation of sandwich panels was minimized at the staking sequence of [$0_2$/90]s and that of composite strut was lowest at the angle of [0/${\pm}45$]s Also there was no buckling in the compressive loading. By vibration analysis, the natural frequencies of the composite components are much higher than aluminum structures and the expected stiffness condition is satisfied. Then, a composite optical bench was fabricated for tests and all analyses results were verified by structural testing. There were good correlations between two results.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
• /
• pp.343-350
• /
• 2002

The structural stability of pressure housing of SMART CEDM forming pressure boundary must be evaluated. In this paper, the stress and thermal analyses of the upper pressure housing of CEDM are performed for design pressure, hydraulic test pressure and thermal loading. Finite element and boundary condition were generated from the model which is made by I-DEAS program and the stress and thermal analyses were performed by ANSYS Program. The upper Pressure housing was analysed using 2D axisymmetric model because it is symmetry about an axis. The stress values obtained by analysis were compared with the stress intensity limit of ASME and KEPIC MNB standard.

• 대한기계학회논문집A
• /
• 제33권9호
• /
• pp.949-956
• /
• 2009

The C(t)-integral describes amplitude of stress and strain rate field near a tip of stationary crack under transient creep condition. Thus the C(t)-integral is a key parameter for the high-temperature crack assessment. Estimation formulae for C(t)-integral of the cracked component operating under mechanical load alone have been provided for decades. However, high temperature structures usually work under combined mechanical and thermal load. And no investigation has provided quantitative estimates for the C(t)-integral under combined mechanical and thermal load. In this study, 3-dimensional finite element analyses were conducted to calculate the C(t)-integral of elastic-creep material under combined mechanical and thermal load. As a result, redistribution time for the crack under combined mechanical and thermal load is re-defined through FE analyses to quantify the C(t)-integral. Estimates of C(t)-integral using this proposed redistribution time agree well with FE analyses results.

• 한국유체기계학회 논문집
• /
• 제8권6호
• /
• pp.40-46
• /
• 2005

Because of design and manufacturing costs, it is important to predict an expected life of bellows with component stresses of bellows as its design factors and material characteristics. In this study, numerical analyses are carried out to elucidate the thermal and flow characteristics of the bellows-seal gate and globe valves for high temperature (max. $600^{\circ}C$) and for high pressure (max. $104 kgf/cm^2$) conditions. Using commercial codes, FLUENT, which uses FVM and SIMPLE algorithm, and ANSYS, which uses FEM, the pressure and temperature fields are graphically depicted. In addition, when bellows have an axial displacement, thermal stress affecting bellows life is studied. The pressure and temperature values obtained from the flow analyses are adopted as the boundary conditions for thermal stress analyses. As the result of this study, we got the reasonable coefficients for valve and thermal stress for bellows, compared with existing coefficients and calculated values.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2002년도 춘계학술대회 논문집
• /
• pp.39-43
• /
• 2002

A new model for heat transfer and thermal deformation analysis according to strip mm in coiling process has been proposed. Finite difference analyses for heat transfer of cold rolled coil have been carried out under various coiling tensions and strip crown using the equivalent thermal conductivity for the radial direction of cold rolled coil which is a function of strip thickness, surface characteristics and compressive pressure. The compressive pressure is calculated from a equation expressed as a function of hoop stress and coil tension considering strip mm obtained by experiment. Finite element method for thermal deformation of cold rolled coil has been performed to investigate the effects of the strip crown, the coil tension and temperature. From these analyses, it is found that the axial inhomogeneity of thermal deformation is increased as the strip crown, compressive pressure, and temperature drop in cold coiled strip increase.