• Title/Summary/Keyword: thermal design

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Design of a tumable Alexandrite laser resonator considering thermal lensing effect (Thermal lensing 효과를 고려한 tunable Alexandrite laser의 공진기 설계)

  • 윤태현
    • Proceedings of the Optical Society of Korea Conference
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    • 1989.02a
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    • pp.1-4
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    • 1989
  • The Alexandrite (Cr:BeAl2O4) laser is one of the promising tunable (vibronic) solid state laser developed recently in the near infrared region (700~800nm) of the spectrum. The thermal lensing effect of rod may effect stable mode osicillation of the solid state laser. A design procedure of the Alexandrite laser resonator considering rod thermal lensing effect and misaligment sensitivity of the resonator will be presented.

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An Experimental Study on the Thermal Efficiency of the Ondol House Beating System (온돌의 열효율에 관한 실험적 연구)

  • Bae soonhoon;Kang Shin-Hyoung
    • The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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    • v.4 no.3
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    • pp.183-190
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    • 1975
  • Most Korean houses are heated by the Ondol heating system. There has been, however, no reasonable design procedure availabe yet for the system. The conventional design should be improved to have auniform floor surface. temperature distribution and to have a high thermal efficiency. Thermal efficiencies of the ondol were defined and the method of experimentation was studied. An experiment, using a life-size model which was well insulated, was performed to observe the variation in thermal efficiency as the length of fuel burning time was varied.

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THERMAL BALANCE MODELLING AND PREDICTION FOR A GEOSTATIONARY SATELLITE (정지궤도 위성의 열평형 시험 모델링 및 예비 예측)

  • Jun, Hyoung-Yoll;Kim, Jung-Hoon
    • 한국전산유체공학회:학술대회논문집
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    • 2009.04a
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    • pp.142-147
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    • 2009
  • COMS (Communication, Ocean and Meteorological Satellite) is a geostationary satellite and has been developing by KARI for communication, ocean and meteorological observations. It will be tested under vacuum condition and very low temperature in order to verify thermal design of COMS. The test will be performed by using KARI large thermal vacuum chamber, which was developed by KARI, and the COMS will be the first flight satellite tested in this chamber. The purposes of thermal balance test are to correlate analytical model used for design evaluation and predicting temperatures, and to verify and adjust thermal control concept. KARI has plan to use heating plates to simulate space hot condition especially for radiator panels such as north and south panels. They will be controlled from 90K to 273K by circulating GN2 and LN2 alternatively according to the test phases, while the shroud of the vacuum chamber will be under constant temperature, 90K, during all thermal balance test. This paper presents thermal modelling including test chamber, heating plates and the satellite without solar array wing and Ka-band reflectors and discusses temperature prediction during thermal balance test.

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Thermal Stress at the Junction of Skirt to Head in Hot Pressure Vessel (고온 수직형 압력용기 Skirt 부의 열응력에 관한 연구)

  • 한명수;한종만;조용관
    • Journal of Welding and Joining
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    • v.16 no.2
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    • pp.111-121
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    • 1998
  • It is well recognized that a excessive temperature gradient from the junction of head to skirt in axial direction in a hot pressure vessel can cause unpredicted high thermal stress at the junction and/or in axial direction of a skirt. this thermal stress resulting from axial thermal gradient may be a major cause of unsoundness of structural integrity. In case of cyclic operation of hot pressure vessels, the thermal stress becomes one of the primary design consideration because of the possibility of fracture as a result of cyclic thermal fatigue and progressively incremental plastic deformation. To perform thermal stress analysis of the junction and cylindrical skirt of a vessel, or, at least, to inspect quantitatively the magnitude and effect of thermal stress, the temperature profile of the vessel and skirt must be known. This paper demonstrated the temperature distribution and thermal stress analysis for the junction of skirt to head using F.E. analysis. Effect of air pocket in crotch space was quantitatively investigated to minimize the temperature gradient causing the thermal stress in axial direction. Effect of the skirt height on thermal stresses was also studied. Analysis results were compared with theoretical formulas to verify th applicability to the strength calculation in design field.

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Design and Performance Test of a Cryogenic Blower for Space Thermal Environment Simulation (우주 열환경 모사용 소형 극저온 블로워 설계 및 성능평가)

  • Seo, Heejun;Ahn, Sungmin;Huh, Hwanil
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.41 no.10
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    • pp.833-839
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    • 2013
  • Thermal vacuum test should be performed prior to launch to verify satellites' functionality in a harsh space environment which is represented by extremely cold temperatures and vacuum conditions. A thermal vacuum chamber which consists of a vacuum vessel, a pumping system, and a thermal control system are used to perform thermal vacuum tests of a satellite system and its components. A cryogenic blower is a core component of the closed loop thermal control system for thermal vacuum chambers. This paper describes the fan design of the cryogenic blower, the design of the thermal protection interface between the driving part and the fluid part, which were verified by thermal and structural analyses. The performance of the cryogenic blower is confirmed by similarity test on the test bench.

Thermal Dissipation Study of IT Module Simulation (IT 모듈에서의 열전달 해석과 방열 특성 연구)

  • Kim, Won-Jong
    • Journal of the Korean Society of Industry Convergence
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    • v.23 no.3
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    • pp.427-431
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    • 2020
  • In this Study, as the structure of IT module for smart phone display becomes thin to catch up with slim product trend, the reliability of display module is on the rise as a issue for product design. Especially, almost part of cellular phone should undergo thermal dissipation test. thus many manufacturers have considered design guide line using CAE and simulation for more effective usage of limited resources on the market. This test simulates the case when cellular phone slips through user's fingers while he is talking on the phone. This paper studies a thermal simulation of display module in smart phone. This design for reliability improvements are suggested on the basis of the results of FVM Analysis and display of IT module and smart phone design.

Design Optimization of Plate-Fin Type Heat Sink for Thermal Stability (열적안정성을 위한 평판-휜형 방열판 최적설계)

  • Park, Kyoung-Woo;Choi, Dong-Hoon;Lee, Kwan-Soo;Kim, Yang-Hyun
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.43-48
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    • 2003
  • In this study the optimization of plate-fin type heat sink for the thermal stability is performed numerically. The optimum design variables are obtained when the temperature rise and the pressure drop are minimized simultaneously. The flow and thermal fields are predicted using the finite volume method and the optimization is carried out by using the sequential quadratic programming (SQP) method which is widely used in the constrained nonlinear optimization problem. The results show that when the temperature rise is less than 34.6 K, the optimal design variables are as follows; $B_{1}$ = 2.468 mm, $B_{2}$ = 1.365 mm, and t = 10.962 mm. The Pareto optimal solutions are also presented for the pressure drop and the temperature rise.

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A Study on Improvement of Electic Motor Thermal Performance Using CFD (CFD를 이용한 전동기 냉각성능 개선에 관한 연구)

  • Yang, Pan-Seok;Lee, Ho-Jun;Jung, Won-Bong
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.261-265
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    • 2003
  • As motor performance enhancement by improving electric design has reached its limit and downsizing issue has risen, the importance of thermal design is increasing. In this study, the flow and temperature distribution were reviewed with the help of CFD analysis and this result was compared with the experimental results. Furthermore, parametric analysis with thermal design structure showed that axial duct width but fan capacity is a critical factor to lower the hot spot temperature in electric motor.

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THERMAL CONTROL DESIGN FOR COMS (COMS 특별세션)

  • Jun, Hyoung-Yoll;Kim, Jung-Hoon;Kim, Sung-Hoon;Yang, Koon-Ho
    • Proceedings of the KSRS Conference
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    • 2007.10a
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    • pp.199-202
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    • 2007
  • COMS (Communication, Ocean and Meteorological Satellite) is a geostationary satellite and has been developing by KARI for communication, ocean observation and meteorological observation. Conventional thermal control design, using MLI (Multi Layer Insulation), OSR (Optical Solar Reflector), heater and heat pipe, is utilized. Ka-band components are installed on South wall, while other equipment for sensors are installed on the opposite side, North wall. High dissipating communication units are located on external (surface) heat pipe and are covered by internal insulation blankets to decouple them from the rest of the satellite. External satellite walls are covered by MLI or OSR for insulation from space and for rejection internal heat to space. The ocean and meteorological sensors are installed on optical benches on the top floor to decouple thermally from the satellite. Single solar array wing is adopted in order to secure clear field of view of radiant cooler of IR meteorological sensor. This paper presents principles of thermal control design for the COMS.

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Experimental and finite element parametric investigations of the thermal behavior of CBGB

  • Numan, Hesham A.;Taysi, Nildim;Ozakca, Mustafa
    • Steel and Composite Structures
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    • v.20 no.4
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    • pp.813-832
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    • 2016
  • This research deals with the behavior of Composite Box Girder Bridges (CBGBs) subjected to environmental effects such as solar radiation, atmospheric temperature, and wind speed. It is based on temperature and thermal stress results, which were recorded hourly from a full-scale experimental CBGB segment and Finite Element (FE) thermal analysis. The Hemi-cube method was adopted to achieve the accuracy in temperature distributions and variations in a composition system during the daily environmental variations. Analytical findings were compared with the experimental measurements, and a good agreement was found. On the other hand, parametric investigations are carried out to investigate the effect of the cross-section geometry and orientation of the longitudinal axis of CBGB on the thermal response and stress distributions. Based upon individual parametric investigations, some remarks related to the thermal loading parameters were submitted. Additionally, some observations about the CBGB configurations were identified, which must be taken into account in the design process. Finally, this research indicates that the design temperature distribution with a uniform differential between the concrete slab and the steel girder is inappropriate for describing the thermal impacts in design objective.