• Title/Summary/Keyword: fire safety evaluation

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Mechanical Characteristics of Ultra High Strength Concrete with Steel Fiber Under Uniaxial Compressive Stress (강섬유로 보강된 초고강도 콘크리트의 일축압축 상태에서의 기계적 특성)

  • Choi, Hyun-Ki;Bae, Baek-Il;Choi, Chang-Sik
    • Journal of the Korea Concrete Institute
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    • v.27 no.5
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    • pp.521-530
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    • 2015
  • Design of fiber reinforced ultra-high strength concrete members should be verified with analytical or experimental methods for safety. Members with compressive strength larger than limitation of current design code usually be designed with analytical verification using stress-strain relation of concrete and reinforcements. For this purpose, mechanical characteristics of steel fiber reinforced ultra-high strength concrete were defined under uniaxial compression. Mix proportions of test specimens were based on reactive powder concrete and straight steel fibers were mixed with different volume fraction. Compressive strength of matrix were distributed from 80 MPa to 200 MPa. Effect of fiber inclusion were investigated : increase of compressive strength of concrete, elastic modulus and strain corresponding to peak stress. For the wide range application of investigation, previously tested test specimens were collected and used for investigation and estimation equation. Based on the investigation and evaluation of previous research results and estimation equation of mechanical characteristics of concrete, regression equations were suggested.

Establishment of Mixing Ratio of Multigrain Rice for Adolescent and Aged People and Its Nutritional and Functional Estimation (청소년 및 고령층을 위한 잡곡밥의 혼합비율 설정 및 영양성, 기능성 평가)

  • Jang, Hye-Lim;Kim, Kun-Woo;Jeong, Yong-Jin;Youn, Kwang-Sup;Woo, Sang-Cheul;Yoon, Kyung-Young
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.42 no.1
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    • pp.53-61
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    • 2013
  • This study was conducted to determine the proper mixing ratio of multigrains-added cooked rice for adolescent and aged people and analyze the nutritional and functional properties. As a result of sensory evaluation according to mixing ratio of polish rice and grains, the palatable grain mixing ratio of mixed grain rice for adolescent and aged people was 40% and 30%, respectively. The ratio of general grains to specialized grains was 9:1 in mixed grain rice for adolescent (MGA) and 8:2 in multigrain rice for aged people (MGAP). The ratio of mung bean to BacTae was 2:1 in MGA, and the ratio of adlay to buckwheat was 1:1 in MGAP. MGA contained the highest amount of crude protein, crude fat and minerals among the samples. In contrast, MGAP showed higher amounts of polyphenols and antioxidant activity compared to polished rice and MGA.

Quality Changes in Pulp-containing Apple Juice upon Addition of Vitamin C (비타민 C 첨가에 따른 미세과육 함유 사과주스의 저장 중 품질변화)

  • Park, Nan-Young;Kim, Jae-Hhoa;Seo, Ji-Hyung;Woo, Sang-Cheul;Jeong, Yong-Jin
    • Food Science and Preservation
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    • v.17 no.4
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    • pp.451-456
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    • 2010
  • We investigated changes in the quality of pulp-containing apple juice, during storage, after addition of various amounts of vitamin C, which was stable over time. Neither sugar content nor acidity level varied when vitamin C was added. The pH was slightly lower (pH 4.29-4.30) in juice with added vitamin C than in unsupplemented juice (pH 4.40). The L and b color values fell as vitamin C content rose and the storage period was extended. In sensory evaluation tests, taste and overall acceptability were higher for juice to which vitamin C had been added to 0.02% (w/v) than for unsupplemented juice. Vitamin C levels fell less during storage at $4^{\circ}C$ than at higher temperatures. The alcohol-soluble color (ASC) value fell as the amount of added vitamin C rose, and tended to be lower when juice was stored at $4^{\circ}C$ compared to $37^{\circ}C$. In summary, apple juice containing pulp was optimally stored at $4^{\circ}C$ after addition of 0.02% (w/v) vitamin C

Quality Changes in Apple Juice Containing Pulp upon Sterilization by Hot Water (열수 살균 조건에 따른 과육 함유 사과주스의 품질 변화)

  • Park, Nan-Young;Kim, Jae-Whoa;Woo, Sang-Cheul;Jeong, Yong-Jin
    • Food Science and Preservation
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    • v.17 no.2
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    • pp.230-235
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    • 2010
  • We investigated the physicochemical quality characteristics of apple juice upon sterilization using hot water, and under various storage conditions. None of sugar content, acidity, or pH differed significantly among various sterilization conditions but chromaticity was considerably reduced in sterilized juice compared with control material. The chromaticity of non-sterilized juice decreased significantly after sterilization compared with material supplemented with vitamin C (0.1%, w/v). Fungi, yeast, and aerobic bacteria were detected in juice sterilized at $65^{\circ}C$ for 10 or 20 min, but no microorganisms were observed in juice sterilized by other procedures. Vitamin C content affected sterilization temperature to a greater extent than sterilization time. When juice was stored at $4^{\circ}C$ or $37^{\circ}C$ for 3 weeks after application of different sterilization conditions, almost no change in acidity, sugar content, or pH was observed, regardless of sterilization mode or storage period. However, chromaticity decreased with longer storage. Vitamin C levels were reduced by higher sterilization temperatures. However, longer storage periods had the greatest effect on reduction of vitamin C levels, which tended toward lower values regardless of differences in sterilization and storage conditions. In sensory evaluation tests, all of taste, color, and overall preference were highest for juice sterilized at $75^{\circ}C$ for 20 min. The ASC value was low at a storage temperature of $4^{\circ}C$ and at high sterilization temperatures, and a long storage period was associated with a greater ASC value. Thus, the quality of apple juice was excellent when juice was hot water-sterilized, with additional vitamin C, at $75^{\circ}C$ for 20 min, followed by storage at $4^{\circ}C$.

Evaluation of Field Application and Optimum Operational Condition for Heavy Metals Analysis Using Environment-Friendly Bismuth Film Electrode (친환경 비스무스 필름 전극을 이용한 중금속 분석 최적조건 도출 및 현장 적용성 평가)

  • Kim, So-Youn;Yang, Yong-Woon;Jeon, Sook-Lye
    • Journal of Korean Society of Environmental Engineers
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    • v.33 no.2
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    • pp.137-142
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    • 2011
  • This study was conducted to establish the optimal electrolyte and bismuth concentrations using bismuth film electrode in laboratory and to confirm the possibilities of using this operational condition for heavy metals monitoring in field. In lab test, heavy metal measurement was not accurate more than 600 ppb when heavy metal (Pb, Cd, Zn) range 100~1,000 ppb was measured with bismuth 2,000 ppb. So, bismuth and heavy metal was reacted about 1:1 with ASV method. In electrolyte test, 0.1 M acetate buffer (pH 4.5), 0.1 M chloroacetate buffer (pH 2.0), 0.1 M HCl (pH 2.0), 0.1 M $HNO_3$ (pH 2.0) was tested. As a results, 0.1 M acetate buffer was most suitable in ASV measurement with bismuth film electrode. In field application, Pb, Cd and Zn was measured respectively 36~45 ppb, 84~91 ppb, 90~98 ppb when heavy metal (Pb, Cd, Zn) 100 ppb was spiked in field sample. These results were identified of matrix effect in field sample, So relationship between heavy metal measurement and matrix effects will be studied.

A Study for Enhancing Disaster Operations Management at Seoul Emergency Operations Center - Focused on the Education and Training for Firefighters of Seoul (서울종합방재센터 상황실 재난상황관리능력 제고 방안 - 서울특별시 소방공무원 교육훈련을 중심으로)

  • Park, Soonil;Park, Chanseok
    • Journal of the Society of Disaster Information
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    • v.14 no.4
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    • pp.480-491
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    • 2018
  • Purpose : This study aims to suggest social support composed of organizational support and managerial support would be systematically managed to enhance Disaster Operations Management at Seoul Emergency Operations Center. Method : Emotional labor was used as an independent variable, and organizational commitment was used as a dependent variable to analyze the mediating effects of social support. Results : First, in the aspect of organizational support, the objective evaluation of disaster situation management, disaster situation management emotional labor reduction education and training program development, monitoring of disaster situation management, quality improvement and work imbalance mitigation of firefighters, and emergency coordination managers are needed for systematic work management for emotional labor settlement. Secondly, it is necessary to select competent firefighters in the level of managerial support, to prepare healing measures for structured phased emotional labor for firefighters, and to have counseling competency for managers for emotional labor firefighting officers. Conclusion : In order to improve disaster management ability, education and training programs should be developed to improve organizational commitment based on social support.

Study on the Consequence Effect Analysis & Process Hazard Review at Gas Release from Hydrogen Fluoride Storage Tank (최근 불산 저장탱크에서의 가스 누출시 공정위험 및 결과영향 분석)

  • Ko, JaeSun
    • Journal of the Society of Disaster Information
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    • v.9 no.4
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    • pp.449-461
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    • 2013
  • As the hydrofluoric acid leak in Gumi-si, Gyeongsangbuk-do or hydrochloric acid leak in Ulsan, Gyeongsangnam-do demonstrated, chemical related accidents are mostly caused by large amounts of volatile toxic substances leaking due to the damages of storage tank or pipe lines of transporter. Safety assessment is the most important concern because such toxic material accidents cause human and material damages to the environment and atmosphere of the surrounding area. Therefore, in this study, a hydrofluoric acid leaked from a storage tank was selected as the study example to simulate the leaked substance diffusing into the atmosphere and result analysis was performed through the numerical Analysis and diffusion simulation of ALOHA(Areal Location of Hazardous Atmospheres). the results of a qualitative evaluation of HAZOP (Hazard Operability)was looked at to find that the flange leak, operation delay due to leakage of the valve and the hose, and toxic gas leak were danger factors. Possibility of fire from temperature, pressure and corrosion, nitrogen supply overpressure and toxic leak from internal corrosion of tank or pipe joints were also found to be high. ALOHA resulting effects were a little different depending on the input data of Dense Gas Model, however, the wind direction and speed, rather than atmospheric stability, played bigger role. Higher wind speed affected the diffusion of contaminant. In term of the diffusion concentration, both liquid and gas leaks resulted in almost the same $LC_{50}$ and ALOHA AEGL-3(Acute Exposure Guidline Level) values. Each scenarios showed almost identical results in ALOHA model. Therefore, a buffer distance of toxic gas can be determined by comparing the numerical analysis and the diffusion concentration to the IDLH(Immediately Dangerous to Life and Health). Such study will help perform the risk assessment of toxic leak more efficiently and be utilized in establishing community emergency response system properly.

Performance Evaluation of Advance Warning System for Transporting Hazardous Materials (위험물 운송을 위한 조기경보시스뎀 성능평가)

  • Oh Sei-Chang;Cho Yong-Sung
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.4 no.1 s.6
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    • pp.15-29
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    • 2005
  • Truck Shipment Safety Information, which is a part of the development of NERIS is divided into Optimal Route Guidance System and Emergency Response System. This research is for establishing an advance warning system, which aims for preventing damages(fire, explosion, gas-escape etc.) and detecting incidents that are able to happen during transporting hazardous materials in advance through monitoring the position of moving vehicles and the state of hazardous materials in real-time. This research is peformed to confirm the practical possibility of application of the advance warning system that monitors whether the hazardous materials transport vehicles move the allowed routes, finds the time and the location of incidents of the vehicles promptly and develops the emergency system that is able to respond to the incidents as well by using the technologies of CPS, CDMA and CIS with testing the ability of performance. As the results of the test, communication accuracies are 99$\%$ in freeway, 96$\%$ in arterial, 97$\%$ in hilly sections, 99$\%$ in normal sections, 96$\%$ in local sections, 99$\%$ in urban sections and 98$\%$ in tunnels. According to those results, the system has been recorded a high success rate of communication that enough to apply to the real site. However, the weak point appeared through the testing is that the system has a limitation of communication that is caused in the rural areas and certain areas where are fewer antennas that make communication possible between on-board unit and management server. Consequently, for the practical use of this system, it is essential to develop the exclusive en-board unit for the vehicles and find the method that supplements the receiving limitation of the GPS coordinates inside tunnels. Additionally, this system can be used to regulate illegal acts automatically such as illegal negligence of hazardous materials. And the system can be applied to the study about an application scheme as a guideline for transporting hazardous materials because there is no certain management system and act of toxic substances in Korea.

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Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2014 (설비공학 분야의 최근 연구 동향: 2014년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.7
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    • pp.380-394
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    • 2015
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.

Bond Characteristics and Splitting Bond Stress on Steel Fiber Reinforced Reactive Powder Concrete (강섬유로 보강된 반응성 분체 콘크리트의 부착특성과 쪼갬인장강도)

  • Choi, Hyun-Ki;Bae, Baek-Il;Choi, Chang-Sik
    • Journal of the Korea Concrete Institute
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    • v.26 no.5
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    • pp.651-660
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    • 2014
  • Structural members using ultra high strength concrete which usually used with steel fiber is designed with guidelines based on several investigation of SF-RPC(steel fiber reinforced reactive powder concrete). However, there are not clear design method yet. Especially, SF-RPC member should be casted with steam(90 degree delicious) and members with SF-RPC usually used with precast members. Although the most important design parameter is development method between SF-RPC and steel reinforcement(rebar), there are no clear design method in the SF-RPC member design guidelines. There are many controversial problems on safety and economy. Therefore, in order to make design more optimum safe design, in this study, we investigated bond stress between steel rebar and SF-RPC according to test. Test results were compared with previously suggested analysis method. Test was carried out with direct pull out test using variables of compressive strength of concrete, concrete cover and inclusion ratio of steel fiber. According to test results, bond stress between steel rebar and SF-RPC increased with increase of compressive strength of concrete and concrete cover. Increasing rate of bond stress were decrease with increase of compressive strength of SF-RPC and concrete cover significantly. 1% volume fraction inclusion of steel fiber increase the bond stress between steel rebar and SF-RPC with two times but 2% volume fraction cannot affect the bond stress significantly. There are no exact or empirical equations for evaluation of SF-RPC bond stress. In order to make safe bond design of SF-RPC precast members, previously suggested analysis method for bond stress by Tepfers were evaluated. This method have shown good agreement with test results, especially for steel fiber reinforced RPC.