• Title/Summary/Keyword: Thermal deterioration

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Shrinkage rate and Structure analysis of IV according to Thermal deterioration (열열화 온도에 따른 IV의 수축률 및 조직분석)

  • Choi, Chung-Seog;Kim, Hyung-Rae;Song, Kil-Mok;Kim, Hyang-Kon;Kim, Dong-Ook;Kim, Dong-Woo
    • Proceedings of the KIEE Conference
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    • 2002.07c
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    • pp.1416-1418
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    • 2002
  • In order to examine the thermal properties of the wire materials, we analyzed the shrinkage, the expansion and the form transformation, the surface structure according to the thermal deterioration temperature through the testing method for a heating shrinkage of Korean Industrial Standard(KS C 3004). For IV(600V grade polyvinyl chloride insulated wires), we measured the shrinkage and the expansion rate, analyzed the surface structure using SEM(Scanning Electron Microscope). In the result of this experiment, the shrinkage rate of IV 2.0mm covering was high in comparison with other wires. As the deterioration temperature rises gradually, the covering is molten and harden.

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Anthocyanin Content and Color Stability in Black Rice According to Different Extract Conditions and Selected Stabilizers (흑미의 추출조건에 따른 안토시아닌 함량과 첨가물에 따른 색소 안전성)

  • Lee, Hye-Jeong;Jang, Jae-Seon;Choi, Eun-Young;Kim, Yong-Ho
    • The Korean Journal of Food And Nutrition
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    • v.21 no.2
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    • pp.127-134
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    • 2008
  • The purpose of this study was to analyze the anthocyanin content of black rice crude extract according to different extraction methods, as well as to compare the effects of stabilizers(${\beta}$-cyclodextrin, maltodextrin) and sugars(sucrose, maltose) on anthocyanin color deterioration, which was examined at $100^{\circ}C$ for $120{\sim}180$ min. In the water extract, C3G (cyanidin-3-glucoside) was detected, 3.22 ppm and 3.29 ppm of C3G respectively. In the $60^{\circ}C$ water extract, anthocyanin color deterioration was retarded by 10% sucrose and 1% maltose and the thermal color deterioration was retarded by the additions of 1% maltodextrin and 1% ${\beta}$-cyclodextrin.

Estimation of Deterioration Depth of Rock Slope due to Freezing-thawing (동결융해에 의한 암반사면의 열화심도 산정)

  • Baek Yong;Seo Yong-Seok;Jeong Ja-Hyea;Kwon O-Ii
    • The Journal of Engineering Geology
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    • v.15 no.3
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    • pp.325-335
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    • 2005
  • Deterioration depths of rock slope due to freezing-thawing were calculated using the 1-D heat conductivity equation. The temperature distribution analysis was carried out using temperature distribution data for last two years of the five major cities such as Seoul, Daejeon, Pohang, Gwangju and Cangneung. The analysis was performed based on three different types of rocks, sandstone, granite and gneiss. This study has found that the deterioration depths tend to be greater with the increase of the thermal conductivity coefficient in Seoul, Daejeon and Pohang where showing relatively greater temperature deviations. Regarding the influence of rock types, deterioration depths turned out to be greater in Gwangju and Gangneung where show relatively smaller temperature deviations among the five cities, assuming these cities are on the granite with thermal conductivity of $55,200\;cal/m\timesday\times^{\circ}C$. In contrast, for the other rock types, cities of relatively geater temperature deviations show deeper deterioration depth than the others. Deterioration depths of rock slope in Korea due to freezing-thawing fumed out to be around 8.4 m to 10.7 m.

The Standardized Methods for Improvement of Maintenance Deterioration caused by Fire damage (국제 표준화를 위한 화재이후의 유지관리 시스템 개발)

  • Kwon, Young-Jin;Koo, In-Hyuk;Kim, Dong-Eun;Seo, Dong-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2013.11a
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    • pp.230-231
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    • 2013
  • A fire outbreak in a reinforcement concrete structure looses the organism by different contraction and expansion of hardened cement pastes and aggregate, and causes cracks by thermal stress, leading to the deterioration of the durability. So, concrete reinforcement structure is damaged partial or whole structure system. Therefore accurate diagnosis of deterioration is needed based on mechanism of fire deterioration in general concrete structures. Fundamental information and data on the properties of concrete exposed to high temperature are necessary for accurate diagnosis of deterioration. In this study, consider case of investigation methods and repair work in fire damaged structure concrete.

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The Standardized Methods for Improvement of Maintenance and Performance Construction of Deterioration caused by Fire damage (화재피해 콘크리트의 유지관리 및 시공성능 향상을 위한 표준화방안)

  • Seo, Dong-Goo;Kim, Dong-Eun;Kim, Bong-Chan;Kwon, Young-Jin
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2013.05a
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    • pp.16-18
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    • 2013
  • A fire outbreak in a reinforcement concrete structure looses the organism by different contraction and expansion of hardened cement pastes and aggregate, and causes cracks by thermal stress, leading to the deterioration of the durability. So, concrete reinforcement structure is damaged partial or whole structure system. Therefore accurate diagnosis of deterioration is needed based on mechanism of fire deterioration in general concrete structures. Fundamental information and data on the properties of concrete exposed to high temperature are necessary for accurate diagnosis of deterioration. In this study, consider case of investigation methods and repair work in fire damaged structure concrete.

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Measurement of the construction structure of hot-heated cement using nitrogen adsorption method (질소흡착법을 사용한 고온 가열 시멘트의 세공구조 측정)

  • Kim, Min-Hyouck;Lee, Gun-Cheol
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2020.06a
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    • pp.140-141
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    • 2020
  • Concrete has a lower thermal conductivity or thermal diffusion coefficient compared to other building materials, so it is widely used as fireproof compartment material or refractory material for structures. However, in the event of thermal damage such as fire, cement curing agents and aggregates act differently, resulting in heat generation or deterioration of tissue due to dehydration, resulting in deterioration of physical properties and fire resistance. Therefore, in this study, the processing structure of cement paste is measured through nitrogen absorption method. The test specimen is a cement paste of 40% W/C and is set at 1000 ℃ under heating temperature conditions. As the temperature rose, the micro-pore mass below was reduced based on about 0.01 감소m, but the air gap above that was increased.Thus, in the range of pores measured in nitrogen adsorption, the air mass tended to decrease under high temperature conditions.

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An Experimental Study on the Engineering Properties of Deteriorated Concrete by Fire Damage According to Curing Conditions (화재피해를 입은 콘크리트의 폭력에 대한 양생조건의 영향성 검토에 관한 연구)

  • Na, Chul-Sung;Kim, Young-Sun;Kim, Jae-Hwan;Kwon, Yung-Jin;Kim, Gyu-Yong;Kim, Moo-Han
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05b
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    • pp.557-560
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    • 2006
  • In the existed study, a fire outbreak in a reinforced concrete structure looses the organism by the different contraction and expansion of hardened cement pastes and aggregate, and causes cracks by thermal stress, leading to the deterioration of the durability. So accurate diagnosis of deterioration is needed based on mechanism of fire deterioration in general concrete structures. Fundamental information and data on the properties of concrete exposed to high temperature are necessary for accurate diagnosis of deterioration. Therefore, this study is willing to propose fundamental data for accurate diagnosis of deteriorated concrete structure by fire damage with experiment according to the curing conditions.

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An Experimental Study on the Engineering Properties of Deteriorated Concrete by Fire Damage According to Design Compressive Strength (화재피해를 입은 콘크리트의 폭렬에 대한 설계기준강도의 영향성 검토에 관한 연구)

  • Na, Chul-Sung;Cho, Bong-Suk;Kim, Jae-Hwan;Kwon, Yung-Jin;Kim, Gyu-Yong;Kim, Moo-Han
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05b
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    • pp.465-468
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    • 2006
  • In the existed study, a fire outbreak in a reinforced concrete structure looses the organism by the different contraction and expansion of hardened cement pastes and aggregate, and causes cracks by thermal stress, leading to the deterioration of the durability. So accurate diagnosis of deterioration is needed based on mechanism of fire deterioration in general concrete structures. Fundamental information and data on the properties of concrete exposed to high temperature are necessary for accurate diagnosis of deterioration. Therefore, this study is willing to propose fundamental data for quick and accurate diagnosis of deteriorated concrete structure by fire damage with experiment according to the design compressive strength.

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A Study on the Condition Diagnosis for A Gas-insulated Transformer using Decomposition Gas Analysis (가스분해 분석기법을 활용한 가스 전열 변압기의 상태 진단 연구)

  • Ah-Reum, Kim;Byeong Sub, Kwak;Tae-Hyun, Jun;Hyun-joo, Park
    • KEPCO Journal on Electric Power and Energy
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    • v.8 no.2
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    • pp.119-126
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    • 2022
  • A growing number of gas-insulated transformers in underground power substations in urban areas are approaching 20 years of operation, the time when failures begin to occur. It is thus essential to prevent failure through accurate condition diagnosis of the given facility. Various solid insulation materials exist inside of the transformers, and the generated decomposition gas may differ for each gas-insulated equipment. In this study, a simulation system was designed to analyze the deterioration characteristics of SF6 decomposition gas and insulation materials under the conditions of partial discharge and thermal fault for diagnosis of gas-insulated transformers. Degradation characteristics of the insulation materials was determined using an automatic viscometer and FT-IR. The analysis results showed that the pattern of decomposition gas generation under partial discharge and thermal fault was different. In particular, acetaldehyde was detected under a thermal fault in all types of insulation, but not under partial discharge or an arc condition. In addition, in the case of insulation materials, deterioration of the insulation itself rapidly progressed as the experimental temperature increased. It was confirmed that it was possible to diagnose the internal discharge or thermal fault occurrence of the transformer through the ratio and type of decomposition gas generated in the gas-insulated transformer.

Calculation of Deterioration Depth of Major Rock Type Slopes caused by Freezing-Thawing in Korea (국내 주요 암종별 사면의 동결-융해에 의한 열화심도 계산)

  • Kwon, O-Il;Baek, Yong;Yim, Sung-Bin;Seo, Yong-Seok
    • The Journal of Engineering Geology
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    • v.17 no.3
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    • pp.359-365
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    • 2007
  • Freezing and thawing cycle is one of the major weathering-induced factors in the mechanical weathering of the rock mass. This natural process accelerates rock weathering process by breaking down the parent rock materials and makes soil or weathered rock formation in a rock slope surface zone. It can also cause reduction of the shear strength in slopes. It is important to calculate the deterioration depth caused by freezing-thawing for a slope stability analysis. In this study, deterioration depths of rock slope due to freezing-thawing were calculated using the 1-D heat conductivity equation. The temperature distribution analysis was also carried out using collected temperature distribution data for last five years of several major cities in Korea. The analysis was performed based on the distributed rock types in study areas. Thermal conductivities, specific heats and densities of the calculation rocks are tested in the laboratory. They are thermal properties of rocks as input parameters for calculating deterioration depths. Finally, the paper is showing the calculated deterioration depths of each rock type slopes in several major cities of Korea.