• 설비공학논문집
• /
• 제13권9호
• /
• pp.914-921
• /
• 2001

The objective of this study is to evaluate the design parameters and to develop the cooling and heating load prediction equations of office buildings. The building load calculation simulation was carried out using the DOE-2.1E program. The results of the simulation was used as a data for ANOVA and multiple regression analysis which could develop the load prediction equations.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제21권6호
• /
• pp.114-127
• /
• 2016

An increase of groundwater flux in BHE system creates that ground temperature (locT) becomes lower in summer and higher in winter time. In other words, it improves significantly the performance of BHE system. The size of thermal plume made up by advection driven-flow under the balanced energy load is relatively small in contrast to the unbalanced energy load where groundwater flow causes considerable change in the size of thermal plume as well ground temperature. The ground temperatures of the up gradient and down gradient BHEs under conduction only heat transport are same due to no groundwater flow. But a significant difference of the ground temperature is observed between the down gradient and up gradient BHE as a result of groundwater flow-driven thermal interference took placed in BHE field. As many BHEs are designed under the obscure assumption of negligible groundwater flow, failure to account for advection can cause inefficiencies in system design and operation. Therefore including groundwater flow in the design procedure is considered to be essential for thermal and economic sustain ability of the BHE system.

• 한국구조물진단유지관리공학회 논문집
• /
• 제13권4호통권56호
• /
• pp.159-169
• /
• 2009

본 연구는 다단계 온도프리스트레싱 공법으로 보강된 합성보의 하중재하 실험 및 구조해석을 통하여 온도프리스트레싱 공법의 프리스트레스 도입효과와 단면증가효과를 평가하였다. 연구결과 온도프리스트레싱을 이용한 합성보의 보강공법은 온도프리스트레싱에 의한 프리스트레스 도입 뿐 아니라 커버플레이트의 설치에 의한 단면증가로 합성보의 처짐 또한 감소시킬 수 있으므로 합성보의 효율적인 보강공법으로 적용이 가능할 것이다.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2002년도 추계학술대회 논문집
• /
• pp.205-208
• /
• 2002

Thermal design is required with considering thermal stability to verify the reliability of electric power device with using IGBT. Numerical analysis is performed to analyzed the change in thermal resistance with respect to the various thermal density of heating element. Correlations between thermal resistance and heat generation density are established. With using these correlations, performance curve is composed with respect to the change in thermal resistance of cooling conditions for natural convection and forced convection. Thermal fatigue is occurred at the Inside and outside of IGBT by repeated heat load. The crack is occurred between base plate and ceramic substrate for the inside. When the crack length is 4mm, the failure is occurred. Therefore, Thermal design method considering thermal density, thermal fatigue resistance is presented on this study and it is expected to thermal design with considering life prediction.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집A
• /
• pp.243-249
• /
• 2001

In this study, the progressive inelastic deformation, so called, thermal ratchet phenomenon which can occur in high temperature liquid metal reactor was simulated with thermal ratchet structural test facility and 316L stainless steel test cylinder. The inelastic deformation of the reactor baffle cylinder can occur due to the moving temperature distribution along the axial direction as the hot free surface moves up and down under the cyclic heat-up and cool-down of reactor operations. The ratchet deformations were measured with the laser displacement sensor and LVDTs after cooling the structural specimen which experiences thermal load up to $550^{\circ}$ and the temperature differences of about $500^{\circ}C$. During structural thermal ratchet test, the temperature distribution of the test cylinder along the axial direction was measured from 28 channels of thermocouples and the temperatures were used for the ratchet analysis. The thermal ratchet deformation analysis was performed with the NONSTA code whose constitutive model is nonlinear combined kinematic and isotropic hardening model and the test results were compared with those of the analysis. Thermal ratchet test was carried out with respect to 9 cycles of thermal loading and the maximum residual displacements were measured to be 1.8mm. It was shown that thermal ratchet load can cause a progressive deformation to the reactor structure. The analysis results with the combined hardening model were in reasonable agreement with those of the tests.

• Nuclear Engineering and Technology
• /
• 제45권1호
• /
• pp.99-106
• /
• 2013

Thermal fatigue is a significant long-term degradation mechanism in nuclear power plants. In particular, as operating plants become older and life time extension activities are initiated, operators and regulators need screening criteria to exclude risks of thermal fatigue and methods to determine significant fatigue relevance. In general, the common thermal fatigue issues are well understood and controlled by plant instrumentation at fatigue susceptible locations. However, incidents indicate that certain piping system Tee connections are susceptible to turbulent temperature mixing effects that cannot be adequately monitored by common thermocouple instrumentations. Therefore, in this study thermal fatigue evaluation of piping system Tee-connections is performed using the fluid-structure interaction (FSI) analysis. From the thermal hydraulic analysis, the temperature distributions are determined and their results are applied to the structural model of the piping system to determine the thermal stress. Using the rain-flow method the fatigue analysis is performed to generate fatigue usage factors. The procedure for improved load thermal fatigue assessment using FSI analysis shown in this study will supply valuable information for establishing a methodology on thermal fatigue.

• 전기전자학회논문지
• /
• 제16권1호
• /
• pp.1-6
• /
• 2012

적절한 송전용량으로 전력공급을 안정하게 유지하기 위하여 노후 가공송전선의 열용량이나 수명 평가가 더욱 중요한 관심사가 되었다. 부하정격과 이도/이격거리 모두는 송전용량을 결정하는 중요한 요소들이다. 국내의 2회선 송전선로에 대한 열용량 및 도체수명을 평가하기 위하여, 전기설비기술기준은 물론 이도 및 지상고에 대한 설계기준들이 검토된다. 상정사고를 가정하여 도체온도와 이도를 계산하고 부하용량을 증대시키기 위한 방안이 모색되었다. 본 논문에서는 노후 도체에 대한 열용량과 한계이도를 적절히 평가함으로써, 기존 전력계통의 신뢰성을 보장하기 위한 개선 방안이 제시되었다.

• Composites Research
• /
• 제14권5호
• /
• pp.38-45
• /
• 2001

복합적층판에 반복 열부하사이클을 부여하여 열-음향방출(thermo-AE)신호의 카이저효과Kaiser effects)를 정량적으로 분석하고 이 거동을 음향방출의 발생원인과 관련시켜 해명하였다. 열부하사이클을 반복함에 따라 음향 방출의 총 링다운 카운트수 및 진폭이 급격히 감소하는 카이저 효과를 나타냈다. 이 카이저 효과는 총 링다운 카운트 수의 지수함수로 표현되었다. 열부하 사이클 시에 발생하는 AE는 균열진전에 의만 것이 아니라, 굴곡진 균열면간의 접촉에 의만 마모 및 2차적 미세손상의 발생과 관련되며, 2차 이후의 열부하 사이클 시에는 균열면간의 마찰적 미끄러짐으로 보다 약한 AE가 적은 사상수로 발생했던 것으로 추정되었다 이러한 열-음향방출 거동은 시험편의 종류 및 열부하 시의 최고온도에 따라 다른 특성을 보였다

• 한국태양에너지학회:학술대회논문집
• /
• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
• /
• pp.451-456
• /
• 2012

This study was carried out to evaluate thermal performance of the renewable hybrid heat supply system with solar thermal system and wood pellet boiler for Zero Carbon Green home of apartment houses. The hybrid heat supply system was set up at Korea Institute Energy Research in 2011. The system was comprised of the wood pellet boiler unit with heat capacity designed as 20,000 kacal/hr, a evacuated tubular solar collector 3.74 $m^2$ of aperture area at the $20^{\circ}$ install angle, a 0.3 $m^3$ hot water storage tank, a 0.15 $m^3$ hot water storage tank for space heating. Thermal performance tests for one-house of apartment house were carried out by hot water load and heating load in winter season through the hybrid heat supply system. As a result, hot water energy supplied by the hybrid heat supply system was 11kWh in a day. Solar thermal energy portion was 2.99kWh which is 27% of the total hot water energy supply. wood pellet boiler supply portion was 8.017kWh which is 73% of the total hot water energy supply.

• Journal of Welding and Joining
• /
• 제28권2호
• /
• pp.39-46
• /
• 2010

IIn this study, used is the equivalent loading method based on the inherent strain to predict the welding deformation of panel members. Equivalent loads are computed from the inherent strain distribution around weld line, and then applied for the linear finite element analysis. Thermal deformation of panel members can be, of course, carried out through the rigorous thermal elasto-plastic analysis procedure but it is not practical in applying to predicting the welding deformation of large structures such as blocks found in a ship structure from view of computing time. The present equivalent load approach has been applied to flat plate model to verify the present approach, and to several curved plate models having the curvature in the welding direction to investigate the effect of the longitudinal curvature upon the weld-induced deformation. The results are compared with those by thermal elasto-plastic analysis. As far as the present results are concerned, it can be said that the present approach shows good agreement with the results by welding experiment and the rigorous thermal elasto-plastic analysis. The present approach has been also applied to predict the welding deformation of panel block as for application illustration to practical model.