• Title/Summary/Keyword: heat-damage

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Post-Fire Damage and Structural Performance Assessment of a Steel-Concrete Composite Bridge Superstructure Using Fluid-Structure Interaction Fire Analysis (FSI 화재해석을 이용한 강합성 교량 상부구조의 화재 후 손상 및 구조성능 평가)

  • Yun, Sung-Hwan;Gil, Heungbae
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.41 no.6
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    • pp.627-635
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    • 2021
  • The fire damage and structural performance of a steel-concrete composite superstructure under a highway bridge exposed to fire loading was evaluated. To enhance the accuracy and efficiency of the numerical analysis, a proposed fluid-structure interaction fire analysis method was implemented in Ansys Fluent and Ansys Mechanical. The temperature distribution and performance evaluation of the steel-concrete composite superstructure according to the vertical distance from the fire source to the bottom flange were evaluated using the proposed analysis method. From the analysis, the temperature of the concrete slab and the bottom flange of the steel-concrete composite superstructure exceeded the critical temperature. Also, when the vertical distance from the fire source was 13 m or greater, the fire damage of the steel-concrete composite superstructure was found to within a safe limit.

The Daily Dose and Uses of Pinellia Tuber, Vinegar and Eggshell of Goju-tang in Treatise on Cold Damage Diseases (《상한론(傷寒論)》고주탕(苦酒湯)의 반하(半夏)와 고주(苦酒), 계자각(鷄子殼) 용량과 용도)

  • Ku, Tae-Hun;Kim, In-Rak
    • The Korea Journal of Herbology
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    • v.36 no.3
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    • pp.9-14
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    • 2021
  • Objectives : The purpose of this study was to clarify the daily dose and uses of Goju-tang in Treatise on Cold Damage Diseases. Methods : We compared major editions of Treatise on Cold Damage Diseases with the original text of Supplement to the Essential Prescriptions Worth a Thousand Gold and chose the most appropriate text. If none of the existing texts seemed reasonable, We compared texts item by item. When there is nothing adequate even item by item, it was newly modified. These results were compared with currently distributed Pinellia Tuber and standards of eggs. Results : Goju-tang consisted of Goju(vinegar), Pinellia Tuber and an eggshell. Generally, a daily dose was extracted at once and taken 3 times a day, but in Goju-tang, 4 pieces of Pinellia Tuber and one-third Sheong of Goju(solvent) were used, which were one third of average volume. Pinellia Tuber was used cut in small pieces. And it was boiled gradually by low heat. Goju was mainly to reduce the pungency of Pinellia Tuber by cutting raphides of calcium oxalate. The Pot preparing medicines was eggshell which was chosen by its small size, because the volume of Pinellia Tuber and Goju was one-third of average volume. Since an egg shell is consisted of protein, it didn't react with vinegar(Goju). Conclusions : The 4 pieces of Pinellia Tuber and one-third Sheong of Goju(Vinegar) in the Goju-tang were one-third of average dose, and the eggshell was Pot preparing medicines.

Strength Properties and Elastic Waves Characteristics of Silicon Carbide with Damage-Healing Ability (손상치유 능력을 가지는 탄화규소의 강도 특성과 탄성파 특성)

  • KIM MI-KYUNG;AHN BYUNG-GUN;KIM JIN-WOOK;PARK IN-DUCK;AHN SEOK-HWAN;NAM KI-Woo
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2004.05a
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    • pp.337-341
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    • 2004
  • Engineering ceramics have superior heat resistance, corrosion resistance, and wear resistance. Consequently, these art significant candidates for hot-section structural components of heat engine and the inner containment of nuclear fusion reactor. Besides, some of them have the ability to heal cracks and great benefit can be anticipated with great benefit the structural engineering field. Especially, law fracture toughness of ceramics supplement with self-healing ability. In the present study, we have been noticed some practically important points for the healing behavior of silicon nitride, alumina, mullite with SiC particle and whisker. The presence of silicon carbide (SiC) in ceramic compound is very important for crack-healing behavior. However, self-healing of SiC has not been investigated well in detail yet. In this study, commercial SiC was selected as sample, which can be anticipated in the excellent crack healing ability. The specimens were produced three-point bending specimen with a critical semi-circular crack of which size that is about $50-700{\mu}m$. Three-point bending test and static fatigue test were performed cracked and healed SiC specimens. A monotonic bending load was applied to cracked specimens by three-point loading at different temperature. The purpose of this paper is to report Strength Properties and Elastic Waves Characteristics of Silicon Carbide with Crack Healing Ability.

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A Study on the Damaged Pattern of Dryvit by External Flame (외부화염에 의한 드라이비트의 소손패턴 연구)

  • Park, Young Ju;Hong, Yi Pyo;Lee, Hae Pyeong
    • Journal of the Korean Society of Safety
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    • v.30 no.6
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    • pp.40-47
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    • 2015
  • In this study, temperature characteristics and fire damage form were analyzed to investigate flame spreading form and fire probability from ignition sources subject to drivit component materials which is finishing material in architecture. Ignition sources were limited to a gas torch and exterior panel board fire, and the size of the sample was manufacture in 30 cm length ${\times}$ 50 cm height ${\times}$ 5cm thickness size. Marble (inner wall) + 3 mm drivit (outer wall), marble (inner wall) + 4 mm plaster stone (outer wall), sandwich panel + 3 mm driver bit (outer wall), sandwich panel + 3 mm driver bit + insulation (outer wall), and gypsum board (inner wall) + 3 mm drivit (outer wall) were prepared for the sample. As result of the research for temperature characteristics, large temperature difference by each material was shown in $218^{\circ}C{\sim}995^{\circ}C$ at 30 seconds and $501^{\circ}C{\sim}1078^{\circ}C$ at 300 seconds. Especially when the inner wall was a plaster board, lowest temperature of $501^{\circ}C$ was shown at 300 seconds and marble inner wall showed the following lowest temperature of $900^{\circ}C$. Temperature rising over $1000^{\circ}C$ was shown in other materials. Regarding fire damage form, drivit or gypsum board outer wall parts exposed to fire showed combustion and carbonization to show calcination(breaking phenomenon) and influence of heat exposure was higher as calcination became more severe.

The Evaluation of the thermal degradation and the degree of cure of glass/epoxy composite by ultrasonic technique (복합재료의 열화도 및 경화도에 따른 초음파 특성 연구)

  • 강길호;최원종;박상윤
    • Composites Research
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    • v.16 no.6
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    • pp.33-40
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    • 2003
  • The initial thermal degradation of polymer matrix composite is not observed easily. At the beginning of thermal degradation of polymer matrix composites, phase transformation such as chain scission, oxidation occur, and then micro delamination is produced in matrix and interface between matrix and fiber before blistering. Initial heat damage deteriorate mechanical properties of composites. We presented the detection method of the initial heat damage of composites conveniently using ultrasonic technique. Absorption coefficient and material velocity was measured with thermal degradation and degree of cure. The more thermal degradation was progressed, the more absorption coefficient was increased. When the cure temperature is more high, the absorption coefficient of cured composite is increased and material velocity is decreased. We concluded that cure temperature is more high, the defects such as void is increased and molecular structure cured at high temperature has cross-linking structure which is more absorb the ultrasonic waves.

A Philological Study on the Pathology, Acupuncture and Moxibustion of Alopecia (탈발(脫髮)의 병인병기(病因病機) 및 침구치료(鍼灸治療)에 관한 문헌고찰)

  • Lee, Sang Hyun;Cho, Myoung Rae
    • Journal of Acupuncture Research
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    • v.32 no.2
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    • pp.35-57
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    • 2015
  • Objectives : The purpose of this study is to analyze literature on oriental medicine to investigate the pathology, acupuncture, and moxibustion therapy applicable to alopecia Methods : We searched for the causes of alopecia in the bibliographic data from 41 sources of literature and the acupunctural treatments for alopecia in the bibliographic data from 49 sources of Chinese and Korean literature and from the journals of the acupunctural treatments for alopecia which have been published since 2000. Results : 1. The main causes of alopecia are blood deficiency, blood heat, static blood, depletion of kidney's water, wind excess, seven emotional damage, dietary damage, etc. 2. The acupuncture points frequently used are $GV_{20}$, $GB_{20}$, $ST_{36}$, $SP_6$, $SP_{10}$, $BL_{17}$, $BL_{18}$, $BL_{23}$, $GV_{23}$, $GV_{14}$, $CV_6$, $ST_8$, $KI_3$, $LR_3$, $HT_7$, $LI_{11}$, EX-$HN_1$, and ouch point. 3. New acupuncture therapies, including herbal acupuncture therapy, ear acupuncture therapy, dermal needle therapy, needle-embedding therapy and scalp acupuncture therapy are frequently used to treat alopecia. Conclusions : The acupuncture points frequently used for treating alopecia have characteristics such as tonifying blood, tonifying the liver and kidney, extinguishing wind, activating blood, clearing heat and draining dampness, so they are highly associated with the causes and the mechanisms of alopecia.

Experimental Study on Internal Temperature Change Induced by Heating Element Attached to Tunnel Lining Surface (터널 라이닝 표면에 부착된 발열체로 인한 내부 온도 변화의 실험적 연구)

  • Jin, Hyunwoo;Hwang, Youngcheol
    • Journal of the Korean GEO-environmental Society
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    • v.18 no.11
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    • pp.35-40
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    • 2017
  • The rearside of concrete lining of tunnels constructed in cold region might experience on freezing due to the low temperature. This causes damage of concrete lining resulting in adverse affect on the durability as well as integrity of tunnel structure by causing damage to the concrete lining. In order to prevent the rearside of tunnel lining from freeing, the temperature change inside the concrete lining was measured by attaching a heating element to the tunnel lining surface and generating heat for a certain period of time. A special freezing chamber was developed to conduct the experiments considering in-situ environment. The carbone nanotube (CNT) was used as a heating element in this study. The temperature distribution of the concrete lining was measured by applying the heat to the heating element. The effect of the outside temperature and heating duration were analyzed.

Analysis of the Damage Patterns and Metal Structure of 3 Phase Mold Transformers to which Interlayer Short-circuits have Occurred (층간 단락된 3상 몰드변압기의 소손 패턴 및 금속 조직 해석)

  • Choi, Chung-Seog
    • Journal of the Korean Society of Safety
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    • v.25 no.6
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    • pp.86-91
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    • 2010
  • The purpose of this study is to analyze the damage patterns and metal structure of 3 phase mold transformers collected from places where accidents have occurred. Compared to an oil-immersed transformer, a mold transformer has the advantage of requiring a smaller installation area and can be kept clean, while its disadvantages include the fact that abnormal symptoms of an accident are difficult to discover and its repair is impossible. The capacity of the mold transformers collected from places where accidents have occurred was 200kVA with primary voltages being F23,900V, R22,900V, 21,900V, 20,900V, 19,900V, etc., as well as secondary voltages being 380V, 220V, etc. It was found from the analysis on the diffusion of combustion in the damaged mold transformers that fire occurred first inside the U-phase primary winding and that carbonization and heat were diffused to V-phase and W-phase in V-pattern. In addition, from the analysis on the cross-sectional structure of the metal of the melted high voltage winding using a metallurgical microscope, it was found that the boundary surface, voids, and columnar structure were formed when an interlayer short-circuit had occurred Therefore, even though it is not possible to find the cause for the occurrence of an interlayer short-circuit at the inner side of the primary winding, it is thought that, due to the thermal energy generated when the short-circuit occurred, the heat source was diffused to the upper side and outside, causing a secondary accident.

A Study on the Leakage Evaluation for Power Plant Valve Using Infrared Thermography Method (적외선열화상에 의한 발전용 밸브 누설명가 연구)

  • Lee, Sang-Guk
    • Journal of the Korean Society for Nondestructive Testing
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    • v.30 no.2
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    • pp.110-115
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    • 2010
  • This study was conducted to estimate the feasibility using thermal image measurement that is applicable to internal leak diagnosis for the power plant valve. Abnormal heating of valve surface associated with high temperature steam f10w toward valve outlet side in the condition of low temperature is a primary indicator of leakage problems in high temperature and pressure valves. Thermal imaging enables to see the invisible thermal radiation that may portend impending damage before their condition becomes critical. When steam flow in valve outlet side in the condition of low temperature is converted into heat transmitted through the valve body due to the internal leakage in valve. The existence of abnormally increasable leakage rate in the valve will result in abnormally high levels of heat to be generated that can be quickly identified with a thermal image avoiding energy loss or damage of valve component. From the experimental results, it was suggested that the thermal image measurement could be an effective way to precisely diagnose and evaluate internal leak situation of valve.

Understanding the Phenomenon of "Clear Qi Below, Turbid Qi Above" with Reference to Symptom Patterns of the Sanghallon (Treatise on Cold Damage 傷寒論) ("청기재하(淸氣在下), 탁기재상(濁氣在上)"에 대한 고찰(考察) - 『상한론(傷寒論)』 병증(病症)과의 비교 -)

  • Park, Sang-Kyun;Bang, Jung-Kyun
    • The Journal of Korean Medical History
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    • v.32 no.1
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    • pp.33-42
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    • 2019
  • Objective : Describe the phenomenon of "clear qi below, turbid qi above" as found in the Somun Eumyangeungsangdaelon (Major Essay on Yinyang Resonances and Appearances 素問 陰陽應象大論) and compare this pattern with water-grain dysentery and flatulence symptom patterns in the Sanghallon (Treatise on Cold Damage). Method : Study the annotation of the Hwangjenaegyeong (Yellow Emperor's Internal Classic 黃帝內經) and compare the results with the Sanghallon's water-grain dysentery and flatulence. Conclusions and Results : The causes of water-grain dysentery and flatulence are associated with the ascending and descending properties of Yin and Yang. Additionally, these symptoms can also be caused by pathogenic heat, turbid pathogenic factors, and interruption of the movement of clear and turbid qi. Aspects of water-grain dysentery resemble several patterns found in the Sanghallon. If caused by a weakness of yang qi, it resembles Sayeoktang (四逆湯) syndrome. Weakness of spleen qi resembles Ijungtang (理中湯) syndrome. Flatulence is similar to fullness in the chest syndrome, which in the Sanghallon is caused by an obstruction of cold qi. If there is excessive cold, water-grain dysentery is similar to the syndrome of Gyeolhyung (結胸). If the qi is not scattered, deficiency syndrome is similar to Gyejigejagyaktang (桂枝去芍藥湯) syndrome and excess syndrome is similar to Mahwangtang (麻黃湯) syndrome. When flatulence is caused by fever in chest, it is similar to Chijasitang (梔子?湯) syndrome. When caused by heat and phlegm build up in chest, it is similar to Sipjotang (十棗湯) syndrome.