• Title/Summary/Keyword: Explosive hazard

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Investigation of the effect of internal curing as a novel method for improvement of post-fire properties of high-performance concrete

  • Moein Mousavi;Habib Akbarzadeh Bengar
    • Computers and Concrete
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    • v.33 no.3
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    • pp.309-324
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    • 2024
  • Internal curing, a widely used method for mitigating early-age shrinkage in concrete, also offers notable advantages for concrete durability. This paper explores the potential of internal curing by partial replacement of sand with fine lightweight aggregate for enhancing the behavior of high-performance concrete at elevated temperatures. Such a technique may prove economical and safe for the construction of skyscrapers, where explosive spalling of high-performance concrete in fire is a potential hazard. To reach this aim, the physico-mechanical features of internally cured high-strength concrete specimens, including mass loss, compressive strength, strain at peak stress, modulus of elasticity, stress-strain curve, toughness, and flexural strength, were investigated under different temperature exposures; and to predict some of these mechanical properties, a number of equations were proposed. Based on the experimental results, an advanced stress-strain model was proposed for internally cured high-performance concrete at different temperature levels, the results of which agreed well with the test data. It was observed that the replacement of 10% of sand with pre-wetted fine lightweight expanded clay aggregate (LECA) not only did not reduce the compressive strength at ambient temperature, but also prevented explosive spalling and could retain 20% of its ambient compressive strength after heating up to 800℃. It was then concluded that internal curing is an excellent method to enhance the performance of high-strength concrete at elevated temperatures.

A Study on Workers' Risk-Aware Smart Bands System in Explosive Areas (폭발위험지역 근로자 위험 인지형 스마트밴드시스템에 대한 연구)

  • Lee, Byong-Kwon
    • Journal of Internet of Things and Convergence
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    • v.5 no.2
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    • pp.73-79
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    • 2019
  • Research is underway on services and systems that provide real-time alerts for suffocating gases and potentially explosive materials, but currently smart bend type services are lacking. This study supports real-time identification of explosion hazards due to static electricity in the workplace and immediate elimination of accident occurrence factors, real-time monitoring of worker status and workplace hazards (oxygen, hazardous chemical concentration), and immediate warning and data in case of danger. We propose a method of establishing an accident prevention system through analysis. In this way, various accidents that may occur in industrial sites are monitored using IoT-based intelligent sensor nodes, wireless network technology, data processing middleware, and integrated control system, and real-time risk information at the industrial sites is prevented and accidents are prevented. By supporting a safe working environment, the company can significantly reduce costs compared to post-procurement costs.

Hazard Evaluation on Fire and Explosion Characteristics of Resorcinol (레조르시놀의 화재·폭발 위험성 평가)

  • Lee, Keun Won;Choi, Yi Rac;Song, Se Wook
    • Journal of the Korean Institute of Gas
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    • v.17 no.4
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    • pp.45-50
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    • 2013
  • Resorcinol is widely used as a wood, tire adhesives, and a raw material of synthetic dye. This material with white crystals at room temperature, the particulates in the air can form explosive mixtures. It is known to be an explosion hazard when exposed to heat in a confined space. The study was evaluated fire and explosion characteristics of the resorcinol through thermal analysis, thermal stability, dust explosion characteristics, and the minimum ignition energy. From this study, it can be used to provide a safety information in the using and handling process of the resorcinol.

Risk-based Security Impact Evaluation of Bridges for Terrorism (Security and Risk를 기반으로 한 교량구조물의 재난 안전성 평가)

  • Kang, Sang-Hyeok;Choi, Hyun-Ho;Seo, Jong-Won
    • 한국방재학회:학술대회논문집
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    • 2008.02a
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    • pp.629-632
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    • 2008
  • Risk-based security impact evaluation may be affected by various factors according to numerous combinations of explosive devices, cutting devices, impact vehicles, and specific attack location to consider. Presently, in planning and design phases, designers are still often uncertain of their responsibility, lack of information and training of security. Therefore, designers are still failing to exploit the potential to reduce threats on site. In this study, the concept of security impact assessment is introduced in order to derive the performing design for safety in design phase. For this purpose, a framework for security impact assessment model using risk-based approach for bridge structures is suggested. The suggested model includes of information survey, classification of terror threats, and quantitative estimation of severity and occurrence.

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Technical/Systemic Approach to Safety Assesment of Thermoprocessing Equipment Consuming LNG for Classification of Hazardous Area (LNG를 사용하는 설비에서의 폭발위험장소 적용 및 구분에 대한 제도/기술적 접근방안)

  • Choi, Sang-Won
    • Journal of the Korean Society of Safety
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    • v.26 no.5
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    • pp.33-40
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    • 2011
  • In the hazardous areas where explosive liquids, vapors and gases exist, electrical apparatus/equipment should have explosion-proof construction. The consuming of liquefied natural gas(LNG) has markedly increased in the industrial field, especially in aspect of some thermoprocessing equipment, boiler, dryer, furnace, annealer, kiln, regenerative thermal oxidizer(RTO) and so on. Because it has many merits, clean fuel, safety, no transportation/storage facility and so on. It is strongly recommend that the classification of hazards has to be decided to prevent and protect explosion which may occur in thermoprocessing equipment. In this paper, the operated thermoprocessing equipments in industrial area investigated and explosion risk assessment about LNG leakage from its facilities was performed through numerical calculation and computer simulation. Finally, we suggest the systemic/technical approach for safety assessments of thermoprocessing equipments consumed LNG fuel which are specially subjected to classification of hazardous area.

A Study on Developing of Soldering Flux (납땜 플럭스 개발에 관한 연구)

  • 이통영
    • Fire Science and Engineering
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    • v.14 no.2
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    • pp.33-38
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    • 2000
  • Flux, essentially used in soldering process of PCB (Printed Circuit Board) in electronics industry, contains IPA (Isopropyl alcohol) and methanol, which are highly inflammable and explosive. Hazard Chemical Controlling Law classified methanol as toxic material and Environmental Law classified methanol as VOC (Volatile Organic Compound). So there have been pressing needs of developing substitutes for the existing Flux. New solvent which is non-flammable and main component is DCP having same specific character of the existing Flux. It's been combirated with proper composition ratio adding stabilizer. As a result, it relieved working Environment Allowance thickness 200 ppm to 470 ppm, chance of not been soldered 0.083% to 0%, spread 85% to 87%, power saving resistance 1.0$\times$$10^{12}$$\Omega$ to 6.9$\times$$10^{12}$$\Omega$, which means a lot better than the existing Flux. Therefore, Flux confirmed the chance of improving productivity, safety, environment safety and quality. Also, Flux got a satisfied result after product quality test and product reliability test.

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Explosion Characteristics and Flame Velocity of Suspended Plastic Powders (플라스틱 부유 분진의 폭발특성과 화염전파속도)

  • Han, Ou Sup;Lee, Keun Won
    • Korean Chemical Engineering Research
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    • v.54 no.3
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    • pp.367-373
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    • 2016
  • Many of plastic powders handled in industry are combustible and have the hazard of dust fire and explosion accidents. However poor information about the safe handling has been presented in the production works. The aim of this research is investigated experimentally on explosive characteristics of various plastic powders used in industry and to provide additional data with safety informations. The explosibility parameters investigated using standard dust explosibility test equipment of Siwek 20-L explosion chamber. As the results, the dust explosion index ($K_{st}$) of ABS ($209.8{\mu}m$), PE ($81.8{\mu}m$), PBT ($21.3{\mu}m$), MBS ($26.7{\mu}m$) and PMMA ($14.3{\mu}m$) are 62.4, 59.4, 70.3, 303 and 203.6[$bar{\cdot}m/s$], respectively. And flame propagation velocity during plastic dust explosions for prediction of explosive damage was estimated using a flame propagation model based on the time to peak pressure and flame arrival time in dust explosion pressure assuming the constant burning velocity.

A Study on the Application of Criteria for the Classification of Explosive Hazardous Areas in Flammable Liquid Handling Laboratories (인화성액체 취급 연구실의 폭발위험장소 구분에 관한 기준 적용 연구)

  • Min-Ho, Kim;Jun-Seo, Lee;Eun-Hee, Kim;Byung-Chol, Ma
    • Journal of the Korean Institute of Gas
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    • v.26 no.6
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    • pp.1-8
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    • 2022
  • With the development of the chemical industry, related accidents frequently occur, and fire and explosion accidents account for a large proportion. In order to prevent fire and explosion accidents, places that handle flammable liquids are classified according to the Korean Industrial Standards (KSC IEC60079-10-1) in accordance with the relevant laws. The same applies to laboratories dealing with flammable liquids. This paper verified the applicability of the procedure for classifying explosion hazard areas according to the Korean Industrial Standards when flammable liquid release from the laboratory to form an evaporative pool, and also verified the effect of a change in ventilation speed on the release characteristics. Through this, it was found that it was difficult to apply the criteria for the classification of places at risk of explosion according to the Korean Industrial Standards, and special safety measures should be prepared.

Study on The Heat Transfer and Mechanical Modeling of Fiber-Mixed High Strength Concrete (섬유혼입 고강도 콘크리트의 열전달 및 역학적 거동 해석모델에 대한 연구)

  • Shin, Young-Sub;Han, Tong-Seok;Youm, Kwang-Soo;Jeon, Hyun-Kyu
    • Journal of the Korean Society of Hazard Mitigation
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    • v.11 no.2
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    • pp.45-52
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    • 2011
  • To improve fire-resistance of a high strength concrete against spalling under elevated temperature, fibers can be mixed to provide flow paths of evaporated water to the surface of concrete when heated. In this study, the experiment of a column under fire and mechanical loads is conducted and the material model for predicting temperature of reinforcement steel bar and mechanical behavior of fiber-mixed high strength concrete is suggested. The material model in previous studies is modified by incorporating physical behavior of internal concrete and thermal characteristics of concrete at the elevated temperature. Thermo-mechanical analysis of the fiber-mixed high strength concrete column is conducted using the calibrated material model. The performance of the proposed material model is confirmed by comparing thermo-mechanical analysis results with the experiment of a column under fire and mechanical loads.

A Study on the Ignition Hazard of Flammable Mixtures by Radio-Frequency Spark (고주파 스파크에 의한 가연성 혼합가스의 점화위험성에 관한 연구)

  • Choi, Sang-Won;Lee, Gwan-Hyung;Moon, Jung-Gi
    • Proceedings of the KIEE Conference
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    • 1996.07c
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    • pp.1913-1916
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    • 1996
  • With a progress of electrical and electronic technology, radio-frequency circuits including high frequency components are widely applied to various industrial installations. Some of them are used in hazardous locations where explosive or flammable gases exist. As a result, ignition of such gases may be induced by a spark discharge when the radio frequency circuits are switched on or off. The purpose of this study is to investigate the ignition hazards of acetylene-air and ethylen-air mixtures experimentally based on the IEC 79-3 publication. In this experiment, we used a high frequency resistive circuit which consists of a co-axial cable, a $10{\Omega}$, $20{\Omega}$, $30{\Omega}$, $40{\Omega}$ or $50{\Omega}$ resistor and a power amplifier with frequency range up to almost 1 MHz. Experimental results show that the ignition of the acetylene-air and ethylen-air mixtures due to spark discharge depends primarily on the frequency of the power source in the resistive circuit: the minimum ignition voltage increases gradually with the increase of the frequency.

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