• Title/Summary/Keyword: 열 안정성

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아지드화 나트륨과 여러 가지 고분자 물질의 혼합비에 따른 열 안정성에 관한 연구

  • 박근호;이기철;이경구
    • Proceedings of the Korean Institute of Industrial Safety Conference
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    • 2002.05a
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    • pp.213-216
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    • 2002
  • 산소가 없는 상태에서 비교적 낮은 온도에서의 열, 충격 등에 의해 용이하게 발화, 연소하는 불안정한 물질에 의한 사고는 이전부터 많이 알려져 있다. 최근에는 fine chemical 분야의 발전에 따라 그 위험성이 인식되지 않은 채 제조되는 불안정한 물질이 늘고 있다[1-2].(중략)

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Thermal Stability Analysis of 2-D Spacecraft Appendage (위성체 2-D 구조물의 열 안정성 해석)

  • 윤일성;송오섭;김규선
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2001.10a
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    • pp.99-104
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    • 2001
  • Thermally induced vibration response of solar array is investigated. The solar array model consists of composite thin walled beam and solar blanket, spreader bar. The composite thin walled beam incorporates a number of nonclassical effects of transverse shear, primary and secondary warping, rotary inertia and anisotropy of constituent materials. The solar blanket is a membrane subjected to uniform tension in the z direction. The spreader bar is a rigid member. A coupled thermal structure analysis that includes the effects of structural deformations on heating and temperature gradient is investigated. A stability criterion given in parameters for establishes the conditions for thermal flutter.

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Thermal Stability Analysis of Flexible Beam Spacecraft Appendage (위성체 유연 보 구조물의 열 안정성 해석)

  • 윤일성;송오섭
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.399-406
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    • 2001
  • Thermally induced vibration response of composite thin walled beams is investigated. The thin-walled beam model incorporates a number of nonclassical effects of transverse shear, primary and secondary warping, rotary inertia and anisotropy of constituent materials. Thermally induced vibration response characteristics of a composite thin walled beam exhibiting the circumferentially uniform system(CUS) configuration are exploited in connection with the structural bending-torsion coupling resulting from directional properties of fiber reinforced composite materials and from ply stacking sequence. A coupled thermal structure analysis that includes the effects of structural deformations on heating and temperature gradient is investigated.

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Effect Of Silica Concentration and Crosslinking Agent on Adhesion Properties and Thermal Stability Of UV Cured 2-EHA/AA PSAs (자외선 경화형 2-EHA/AA 점착제의 점착 물성 및 열 안정성에 미치는 실리카 함량 및 경화제 효과)

  • Kim, Ho-Gyum
    • Journal of Adhesion and Interface
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    • v.16 no.2
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    • pp.55-62
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    • 2015
  • It was investigated that the effect of surface modification and concentration of fumed silica on the adhesion properties and thermal stability of 2-EHA/AA pressure sensitive adhesive (PSAs) prepared by UV irradiation. The influence of repeating units of crosslinking agent on PSAs were also studied. From SEM analysis, PSAs synthesized with surface modified silica had finer dispersion of silica particles in polymer matrix due to the interfacial interaction. Results of the study showed that increase in tack and peel strength when under 0.3 wt% of silane treated silica were added in the reaction mixture. The addition of PEGDMA for crosslinking agent offers positive effect on adhesion properties in comparison with PSAs using EGDMA for crosslinker, which may be attributed to high mobility of ethylene oxide repeating units in PEGDMA. From the thermal degradation residue of PSAs, it was revealed that thermal stability was improved with silica addition due to the strong interfacial bonding between silane modified silica and polymer matrix, which may act as a thermal barriers into 2-EHA/AA PSAs.

Thermal Model Correlation and Heater Design Verification for LEO Satellite Optical Payload's Thermal Analysis Model Verification (저궤도 위성 광학탑재체의 열해석 모델 검증을 위한 열모델 보정 및 히터 설계)

  • Kim, Min-Jae;Huh, Hwan-Il;Kim, Sang-Ho;Chang, Su-Young;Lee, Deog-Gyu;Lee, Seung-Hoon;Choi, Hae-Jin
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.39 no.11
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    • pp.1069-1076
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    • 2011
  • All of the satellite components must be operated within the permissible temperature range during the mission in orbit. Therefore, thermal design is performed to develop verified thermal model and to secure thermal stability on the ground. In this study, thermal model correlation was performed to satisfy the criteria of correlation using ground thermal vacuum/thermal balance test results of LEO satellite optical payload. We also secured verified thermal model by controlling operating cycle of flight heaters. In addition, it was confirmed that all components are within the permissible temperature range through conducting orbit environment thermal analysis. We also secured thermal stability of the satellite.

The Development of Econometric Model for Air Transportation Demand Based on Stationarity in Time-series (시계열 자료의 안정성을 고려한 항공수요 계량경제모형 개발)

  • PARK, Jeasung;KIM, Byung Jong;KIM, Wonkyu;JANG, Eunhyuk
    • Journal of Korean Society of Transportation
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    • v.34 no.1
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    • pp.95-106
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    • 2016
  • Air transportation demand is consistently increasing in Korea due to economic growth and low cost carriers. For this reason, airport expansion plans are being discussed in Korea. Therefore, it is essential to forecast reliable air transportation demand with adequate methods. However, most of the air transportation demand models in Korea has been developed by simple regression analysis with several dummy variables. Simple regression analysis without considering stationarity of time-series data can bring spurious outputs when a direct causal relationship between explanatory variables and dependent variable does not exist. In this paper, econometric model were developed for air transportation demand based on stationarity in time-series data. Unit root test and co-integration test are used for testing hypothesis of stationarity.

A Study on Total Fire Risk Assessment of Wallpapers (벽지의 종합적 화재 위험성 평가에 관한 연구)

  • 박미라;김광일;김태구
    • Fire Science and Engineering
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    • v.17 no.1
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    • pp.33-39
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    • 2003
  • The purpose of this study is to evaluate flame retardant performance, thermal stability and toxicity of combustion gases for some commercial wallpapers. ID evaluate flame retardant performance 45 degree combustion experiment method was used and thermal stability was evaluated using DSC and TGA apparatus (OSC-50/Shimadzu, TGA2050/TA Instruments Inc) . Concentrations of CO, $CO_2$, HCN and HCI were measured with (GASTEC/Japan, MSA400 Gas Monitor/Infitron Inc) and toxicity indices using NIST N-Gas Model were applied to evaluate the toxicity of combustion gases. The evaluation produced the following results : First, paper cork and PVC wallpaper treated with flame retardants were found to be suitable for flame retardant performance standards. Second, paper, cork and PVC wallpaper non-treated with flame retardants were shown to be relatively more hazardous because they had greater calorific values and a faster decomposition time than the flame retardant treated wallpapers. Third, the toxicity indices of non-treated wallpapers were found to be higher than those of treated wallpapers, and the toxicity index of PVC wallpapers was higher than those of paper and cork wallpapers.

Heat Conduction in Rock Mass Around Underground Cold Storage Cavern and Estimation of Heat Loads (지하냉동저장공동 주위암반의 열전도 특성 및 열부하 평가)

  • Synn, Joong-Ho;Park, Chan;Park, Yeon-Jun;Kim, Ho-Yeong
    • Proceedings of the Korean Society for Rock Mechanics Conference
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    • 1999.03a
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    • pp.59-64
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    • 1999
  • 지하암반은 계절적 대기온도 변화의 영향을 거의 받지 않는 온도조건 및 뛰어난 단열성으로 인해 물류의 저온냉동저장이나 액화연료의 저장 등을 위한 좋은 대상으로 인식되고 있다. 이러한 분야에 있어서 암반의 열물성 및 열유동 특성은 매우 중요한 요소로서, 이는 장기적인 에너지절약 및 지하구조물의 열역학적 안정성의 정확한 평가와 직접적 연관이 된다. (중략)

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신.구 규격 PE배관 안정성 확보를 위한 식별표시

  • Korea Mechanical Construction Contractors Association
    • 월간 기계설비
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    • no.8 s.205
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    • pp.53-53
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    • 2007
  • 한국가스안전공사는 하반기부터 신 규격 PE배관은 4열 보조선(검정색) 표시 배관 사용을 원칙으로 하되, 4열 보조선이 없는 신 규격 PE배관을 사용할 경우 로케팅와이어를 따라 길이방향으로 100% 검정색 PE Tape를 1열로 부착할 것을 권고했다. 한국가스안전공사의 이같은 조치는 지난 2006년 12월 1일부터 PE배관 KS규격(KSM 3514)이 ISO규격을 인용한 신 KS규격으로 변경됨에 따라 신·구 규격 PE배관 상호 접합시 안전성 확보방안이 요구됨에 따른 것이다.

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