• Title/Summary/Keyword: Thermal Test

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A STUDY ON THE THERMAL FATIGUE TEST AND ANALYSIS METHOD FOR THE DEVELOPMENT OF BRAKE DISK MATERIALS

  • Lim, Choong-Hwan;Goo, Byeong-Choon
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.127-131
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    • 2008
  • In the disk braking of the railway trains, kinetic energy of the vehicles is converted into thermal energy by friction between a brake disk and the pad materials. This can be cause of the iterative thermal shock and generates thermal cracks on the brake disk surface. In this study, we show the comparative thermal fatigue test procedures and thermal crack analysis process to evaluate the thermal fatigue characteristics of candidate materials designed for development of heat-resistant brake disk material. We carried out tests on the conventional brake disk materials used for Saemaul and Mugunghwa trains, then we comparatively analyzed the thermal crack initiation and propagation on the surface of a specimen. A thermal fatigue test procedure and a crack analysis process were suggested to evaluate the heat resistance of the developed materials at later studies.

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THERMAL MODEL CORRELATION OF A GEOSTATIONARY SATELLITE (지구 정지궤도 위성의 열해석 모델 보정)

  • Jun, H.Y.;Kim, J.H.
    • Journal of computational fluids engineering
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    • v.16 no.3
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    • pp.59-65
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    • 2011
  • COMS (Communication, Ocean and Meteorological Satellite) is a geostationary satellite and was developed by KARI for communication, ocean and meteorological observations. COMS was tested under vacuum and very low temperature conditions in order to correlate thermal model and to verify thermal design. The test was performed by using KARI large thermal vacuum chamber. The COMS S/C thermal model was successfully correlated versus the 2 thermal balance test phases. After model correlation, temperatures deviation of all individual units were less than $5^{\circ}C$ and global deviation and standard deviation also satisfied the requirements, less than $2^{\circ}C$ and $3^{\circ}C$. The final flight prediction was performed by using the correlated thermal model.

Development and Design Verification of Thermal Control Subsystem for EOS-C Ver.3.0 Flight Model (EOS-C Ver.3.0 비행모델의 열제어계 개발 및 설계 검증)

  • Chang, Jin-Soo;Yang, Seung-Uk;Kim, Ee-Eul
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.40 no.10
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    • pp.872-881
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    • 2012
  • The Flight Model (FM) of a high-resolution electro-optical camera (EOS-C Ver.3.0), the mission payload of an Earth observation satellite, was successfully developed by Satrec Initiative. We designed it to give improved thermal representatives compared with the Structural-Thermal Model (STM) by optimizing the thermal characteristics based on the STM thermal vacuum test results. We developed the FM and verified the workmanship by performing the acceptance level thermal vacuum test. We also conducted the verification of its Thermal Mathematical Model (TMM) by the thermal balance test. As the result, it was confirmed that TMM faithfully represents the thermal characteristics of the EOS-C Ver.3.0 FM.

A Study on the Fracture Mode Characteristics of Automotive Application Component Lead-free Solder Joints (자동차 전장부품 무연솔더 접합부의 파괴모드 특성에 관한 연구)

  • Jeon, Yu-Jae;Kim, Do-Seok;Shin, Young-Eui
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.6
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    • pp.90-96
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    • 2011
  • In this study, the characteristic of fractured portion and shape on solder joints were investigated according to the thermal shock test for Automotive Application Component using Sn-3.0Ag-0.5Cu solder, which has a outstanding property as Lead-free solder. The value of pull and shear strength was decreased in principle after 432 cycles thermal shock test. In addition, fracture mode was verified by using EDS and SEM to observe fractured shape on the solder joints before and after thermal shock. In before thermal shock test, the fracture mode revealed typically solder layer's fracture mode. In after thermal shock test, we identified multiple fracture mode of the ductile and brittle fracture. Even though same composition of solder was used to experimental for estimating. the fracture mode varied on the fracture portion's height and the directional angles of shear strength. In conclusion, we identified that mechanical strength was affected on the solder layer's fracture mode.

A Study of Thermal Shock Characteristics on the Joints of Automotive Application Component using Sn-3Ag-0.5Cu Solder (Sn-3Ag-0.5Cu계 솔더를 이용한 자동차 전장 부품 접합부의 열충격 특성에 관한 연구)

  • Jeon, Yu-Jae;Son, Sun-Ik;Kim, Do-Seok;Shin, Young-Eui
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.8
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    • pp.611-616
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    • 2010
  • This study investigated the characteristics of fracture behavior and mode on solder joints before and after thermal shock test for automotive application component using Sn-3.0Ag-0.5Cu solder, which has a outstanding property as lead-free solder. The shear strength was decreased with thermal cycle number, after 432 cycles of thermal shock test. In addition, fracture mode was verified to ductile, brittle fracture and base materials fracture such as different kind fractured mode using SEM and EDS. Before the thermal shock, the fractured mode was found to typical ductile fracture in solder layer. After thermal shock test, especially, Ag was found on fractured portion as roughest surface. Moreover, it occurred delamination between a PCB and a Cu land. Before thermal shock test, most of fractured mode in solder layer has dimples by ductile fracture. However, after thermal shock test, the fractured mode became a combination of ductile and brittle fracture, and it also could find that the fracture behavior varied including delamination between substrate and Cu land.

A Study on the Standardization of Test Method of Flat-Plate Liquid-heating Solar Collectors (액체식 평판형 태양열 집열기 성능 실험의 표준화에 관한 연구)

  • 윤석범
    • Journal of the Korean Society of Safety
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    • v.5 no.3
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    • pp.27-32
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    • 1990
  • Standardization of solar collector test method is desirable for improvement solar collector quality and Valuation of collector thermal performance. In the present work, test loop proposed by Chun, is modified for convenience of test and obtained accurate collector thermal performance. An experimental investigation hat been carried out with a modified collector test loop under a real sun condition in order to confirm the utility of modified test loop and study the effect of variation of flow rate on thermal efficiency, the range of optimum flow rate and critical incident angle.

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Thermal Vacuum Test of the Phase Change Material Thermal Control Unit Loaded on the Satellite Flight Model and Thermal Model Correlation with Test Results (위성에 탑재된 상변화물질 열제어장치 비행모델의 열진공시험 및 이를 통한 열해석 모델 보정)

  • Cho, Yeon;Kim, Taig Young;Seo, Joung-Ki;Jang, Tae Seong;Park, Hong-Young
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.50 no.10
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    • pp.729-737
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    • 2022
  • Melting and icing process of the PCMTCU(Phase Change Material Thermal Control Unit) installed on the NEXTSat-2, which is scheduled to be launched in the second half, was investigated through the results of satellite-level TVT(Thermal Vacuum Test). As a result of the test, it was confirmed that the latent heat of PCM contributes to the temperature stabilization of the heating components. The thermal model for numerical analysis of the PCMTCU was correlated to acquire a reasonable degree of accuracy using the collected temperature measurements during TVT. The periodic temperature variation of the PCMTCU in normal on-orbit operation was predicted with the correlated thermal model, and the quantitative contribution of the PCM on the thermal energy management was evaluated with the liquid fraction. It will receive flight telemetry from the NEXTSat-2 after the launch, and complete the space verification of the PCMTCU.

Clinical Study of Bell's Palsy with DITI and Nerve Conduction Test(EN0G and EMG) (DITI 및 전기신경전도검사(EN0G 및 EMG)를 이용한 구안와사(Bell's palsy) 환자에 대한 임상적 고찰)

  • Kim, Jin-man;Hong, Chul-hee;Du, In-sun;Hwang, Chung-yeon;Kim, Nam-kwen;Park, Min-chul;Lee, Sang-kwan;Jung, Sang-su;Yoon, Jun-chul
    • The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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    • v.16 no.2
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    • pp.189-211
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    • 2003
  • The clinical data and thermographic imaging were analyzed on the 38 cases of Bell's palsy who were treated admission in the Oriental Medicine Hospital of Wonkwang University from January 2002 to May 2003. 38 patients with Bell's palsy were within one week after the onset of the paralysis, and thermal type in the DITI were hypo or hyper generally. Nerve conduction test(ENOG and EMG) examined in two weeks after onset. We studied interaction effect between thermal type and paralysis grade on admission day. We studied each main effect ; paralysis grade on admission day - nerve conduction test, nerve conduction test - thermal type, thermal type - paralysis grade after 4 weeks, paralysis grade on admission day - paralysis grade after 4 weeks, sasang constitution - nerve conduction test. The following results were obtained that interaction effect between thermal type and paralysis grade on admission day showed no significance, each main effect ; paralysis grade on admission day - nerve conduction test, paralysis grade on admission day - paralysis grade after 4 weeks, showed significance, each main effect ; nerve conduction test - thermal type, thermal type - paralysis grade after 4 weeks, sasang constitution - nerve conduction test, showed no significance.

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Limitations and improvement of the in situ measurements of ground thermal conductivity in Korea (국내 지중열전도도 측정 방법의 한계 및 개선 방향)

  • Shim, Byoung Ohan
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.05a
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    • pp.195.2-195.2
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    • 2011
  • The borehole heat exchanger of Geothermal Heat Pump (GHP) system should be sustainable and cost effective for long term operation. To guaranty the performance of the system thermal Response Tests (TRTs) with simple recommended procedures have been applied in many countries. Korea government developed a standard TRT procedure in order to control the quality on GHP projects. In the TRT procedure interpretation method has a rule that data set has to be interpreted by the line source model(LSM). The LSM employes some assumptions that surrounding medium is homogeneous and the line source is infinite and constant heat flux, however real ground condition is unisotropic and heterogeneous, and showing regional or local ground water flows in many cases. We need to develope improved evaluation models to estimate accurate ground thermal conductivity with respect to geological and influence of ground water because current TRT standard test procedure has limitations to be applied for every locations and system. This study surveyed the uncertainty of the thermal parameters from the interpretation method considering different evaluation period. The interpretation of 208 TRT data sets represents limitations of LSM application that some obtained ground thermal conductivities are statistically unstable and convergence time of ground thermal conductivity over test period shows trends responding the length of test period. This evaluation study will be helpful to provide some effective procedure for the thermal parameter estimation and to complement current TRT standard procedure.

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Evaluation of performance of closed-loop vertical ground heat exchanger by In-situ thermal response test (현장 열응답 시험을 통한 수직 밀폐형 지중열교환기의 성능 평가)

  • Lee, Chul-Ho;Park, Moon-Seo;Kwak, Tae-Hoon;Choi, Hang-Seok
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.03a
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    • pp.229-239
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    • 2010
  • Performing a series of in-situ thermal response tests, the effective thermal conductivity of six vertical closed-loop ground heat exchangers was experimentally evaluated and compared each other, which were constructed in a test bed in Wonju. To compare thermal efficiency of the ground heat exchangers in field, the six boreholes were constructed with different construction conditions: grouting materials (cement vs. bentonite), different additives (silica sand vs. graphite) and the shape of pipe-sections (general U-loop type vs. 3 pipe-type). From the test results, it can be concluded that cement grouting has a higher effective thermal conductivity than that of bentonite grouting, and the efficiency of graphite better performs over silica sand as a thermally-enhancing addictive. In addition, a new 3 pipe-type heat exchanger provides less thermal interference between the inlet and outlet pipe than the conventional U-loop type heat exchanger, which results in superior thermal performance.

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