• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.573-578
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• 1997

기존 냉각수 주입 계통의 안전성 및 신뢰도를 높이려는 노력에서 미국, 일본, 이태리 등 여러 나라에서는 증기 주입기에 대한 분석 기법 개발과 실험을 통한 연구가 활발하게 진행되고 있다. 이들이 이상 유동 현상이 일어나는 혼합 노즐을 해석하기 위해 사용한 방법은 제어체적 분석기법으로, 이 분석 방법에서는 응축 메커니즘을 고려할 수 없다. 본 연구에서는 이러한 사항을 개선하기 위해 혼합 노즐 해석시 one dimensional two fluid model을 적용하여 상간의 운동량 및 에너지 전달을 고려함으로써 비교적 정확하게 해석 모델 및 코드를 개발하였고, 출력 변수인 방출 압력과 방출 온도를 계산하였으며, 개발한 해석 코드를 검증 및 분석을 하기 위해 ANL 실험자료를 근거로 하였다. 개발한 코드에 의해 계산된 방출 압력은 ALN 실험치에 비해 높은 경향을 보여 주었지만 ANL에서 제어 체적 분석 기법을 적용하여 이론식으로 계산한 값보다는 비교적 정확한 경향을 보여 주었다.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.9
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• pp.733-739
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• 1989

Fixed boundary MHD static equilibrium for the axisymmetric toroidal plasma is analyzed numerically. The Grad-Shafranov equation is solved using finite element method. The toroidal current term is expressed by plasma pressure and toroidal field function. The numerical results are compared to the Solovev analytic equilibrium for the verification of the solution. For SNUT-79 tokamak device in Seoul National University, the flux surfaces, the toroidal current profiles, the safety factor q and average beta values are obtained when the p and g profiles are varied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.5
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• pp.373-377
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• 2005

In this paper the gas leakage controller in processing chamber for semiconductor manufacturing is proposed. A pressure sensor is connected between the final valve and the numeric valve. A pressure sensor signal and a numeric valve signal are controlled by a proposed digital circuit module. Gas leakage condition, producing by 2nd plasticity in semiconductor process, display at LED. The proposed controller module is useful for monitoring the gas flow for preventing the critical process gas leakage.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.15 no.1
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• pp.1-7
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• 2019

In this paper, the regulations and technical standards related to qualification of safety grade equipment in nuclear power plants are critically reviewed with the qualification procedure in terms of structures, systems, and equipment in nuclear power plants. These facilities should be designed and constructed to protect from natural conditions or disasters and to perform their safety functions even in case of postulated accidents. Equipment Qualification is to demonstrate that the safety related equipment is designed and constructed to perform their safety functions under normal and accident conditions. It is classified into environmental qualification and seismic qualification.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2022.10a
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• pp.215-216
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• 2022

유입된 공기가 배출될 때 중앙코어형 건축물이나 지하층처럼 밀폐된 공간의 경우 옥내에 부압이 형성되며 제연구역과 과도한 압력차이로 출입문 개방에 필요한 힘을 초과하는 등 많은 문제들을 야기할 수 있다. 유입공기 배출댐퍼가 적용된 ◯◯오피스텔을 사례로 실제 TAB(Testing, Aejuwting, Balancing)를 수행하여 유입공기 배출에 따른 영향과 제연성능의 개선방안을 알아보고자 하였다. 유입공기 배출댐퍼를 순차적으로 개방해 가며 차압 및 방연풍속 등의 변화를 기록한 결과 밀폐된 복도에서 유입 공기 배출댐퍼가 개방되면 복도에 부압이 형성되고 제연구역에 과도한 압력이 발생하여 출입문 개방에 필요한 힘을 초과하였다. 유입공기 배출댐퍼 개방 층수를 증가시켜 TAB를 수행한 결과 3개층 까지 개방하여도 방연풍속이 확보되었다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.517-534
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• 2021

Hydrogen fuel is emerging as an new energy source to replace fossil fuels in that it can solve environmental pollution problems and reduce energy imbalance and cost. Since hydrogen is eco-friendly but highly explosive, there is a high concern about fire and explosion accidents of hydrogen fueled vehicles. In particular, in semi-enclosed spaces such as tunnels, the risk is predicted to increase. Therefore, this study was conducted on the applicability of the equivalent TNT model and the numerical analysis method to evaluate the hydrogen explosion pressure in the tunnel. In comparison and review of the explosion pressure of 6 equivalent TNT models and Weyandt's experimental results, the Henrych equation was found to be the closest with a deviation of 13.6%. As a result of examining the effect of hydrogen tank capacity (52, 72, 156 L) and tunnel cross-section (40.5, 54, 72, 95 m²) on the explosion pressure using numerical analysis, the explosion pressure wave in the tunnel initially it propagates in a hemispherical shape as in open space. Furthermore, when it passes the certain distance it is transformed a plane wave and propagates at a very gradual decay rate. The Henrych equation agrees well with the numerical analysis results in the section where the explosion pressure is rapidly decreasing, but it is significantly underestimated after the explosion pressure wave is transformed into a plane wave. In case of same hydrogen tank capacity, an explosion pressure decreases as the tunnel cross-sectional area increases, and in case of the same cross-sectional area, the explosion pressure increases by about 2.5 times if the hydrogen tank capacity increases from 52 L to 156 L. As a result of the evaluation of the limiting distance affecting the human body, when a 52 L hydrogen tank explodes, the limiting distance to death was estimated to be about 3 m, and the limiting distance to serious injury was estimated to be 28.5~35.8 m.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2003.10a
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• pp.335-338
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• 2003

최근의 통계에 따르면 국내의 인터넷 인용율은 2000년도에 44.7%, 2001년도에 56.6%, 2002년도에는 55.2%로 아이슬랜드(60.8%), 스웨덴(57.3%)에 이어 세계에서 세번째로 높은 것으로 나타났다. 또한 인구 100명당 PC보급율 또한 미국(62.5대), 덴마크(57.68대)에 이어 한국(55.58대)이 세계3위를 기록해 명실상부한 정보화 선진국임이 입증되고 있다. 따라서 잘 발달된 infrastructure을 이용하는 기술개발은 초고속정보이용을 가능케하고 있다. 근래에 들어 인터넷을 기반으로 기본적인 활용인 문자, 음성 및 영상 전송 등의 데이터 전송뿐만 아니라, 근래에는 인터넷을 통한 remote control 및 monitoring system에 대한 연구가 활발히 진행되고 있다. 기존의 증류공정은 DCS(Dispersion Control System)로써 공정상태(온도, 압력, 유량, 레벨, 순도등)를 Control room까지 선로를 통하여 신호전달이 이루어지고 있다. 따라서, 제한된 지역에서만 I/O(Input/output)이 이루어지고 있다. 이로 인해 안전감시시스템의 효율성이 떨어지고 있는 게 사실이다. 본 연구에서는 PC기반의 프로그램을 바탕으로 인터넷을 이용한 remote control 및 monitoring system을 개발함으로써 close Network에서 Open Network으로 발전시켰다. 여기서 local plant의 안전시스템 알고리즘은 그대로 Server system에 도입하였으며 사용자의 실정에 맞게 손쉽게 설정을 할 수 있도록 확장성을 높였다. 이는 PC기반의 시스템을 구축함으로써 가능하게 된 것이다. 또한, 웹 상에서의 무차별적 접근으로부터 보호하기 위하여 감시 대상의 성질에 따라 프로그램상에서 차별적 접근형식을 택할 수 있으며, control room의 indicator들과 controller를 프로그램상에 그대로 이식시킴으로써 감시자에게 충분한 정보제공 및 원격제어가 가능하도록 하고있다.

• Journal of the Korean Society for Railway
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• v.15 no.3
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• pp.266-271
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• 2012

This study was carried out for the purpose of improving driving safety and comfort of the railways quickly becoming popular. To conducted gas pressure welding to ensure the strength safety of continuous welded rail and rotating bending test tensile test was conducted. The element to determine the tensile strength of gas pressure welds at experiments be attributed to more upsetting length than pressure, according to increases of upsetting length, from brittle fracture to ductile fracture was observed. Through the biopsy of the fracture surface, according to the presence of brittle fracture could be evaluated to strength safety. In addition, mechanical strength of gas pressure welding depending on changes in upsetting length was different. Rotary bending test results were obtained to the infinite life according to exhibited higher fatigue limit of 373MPa at upsetting length 25mm.

• Korean Chemical Engineering Research
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• v.61 no.1
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• pp.80-88
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• 2023

Ensuring safety in the designing of manufacturing and handling facilities for low-density polyethylene (LDPE) is difficult because there are no standards for the dust explosion characteristics of LDPE. In this study, a dust explosion test was performed on two dust samples collected from a bag filter (LDPE 1) during the LDPE manufacturing process and sedimentary dust (LDPE 2) leaked outside a facility such as a silo, and the LDPE 2 explosion test results were summarized. Particle size analysis showed that the volume-based particle diameter (median) was 95.04 ㎛ and the number density was 0-1 ㎛. The maximum explosion pressure (P_max) was 6.6 bar, and the maximum rate of explosion pressure rise was 366 [bar/s] at 1500 g/m³. Accordingly, the dust explosion index (K_st) was 99.4 bar·m/s, which was confirmed as ST-1 grade. Moreover, the minimum ignition energy and minimum ignition temperature was 10 mJ and 450 ℃, respectively. Currently, manufacturing and handling design is based on the characteristic values of high-density polyethylene (HDPE). However, as the test results show that LDPE 2 dust has a higher risk than HDPE (particle diameter 61.6 ㎛), caution is required when using the HDPE design criteria in the LDPE manufacturing process.

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.307-312
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• 2023

In this study, a catalytic oxidation-heat recovery system was designed that can remove unreacted with a concentration of about 1% to 6% in the exhaust gas of hydrogen fuel cells and recover heat to ensure safety in the hydrogen economy. The safety system was devised by filling hydrogen oxidation catalysts at room temperature that can remove unreacted hydrogen without any energy source, and an exhaust-heat recovery device was integrated to efficiently recover the heat released from the oxidation reaction. Through CFD analysis, variations in pressure and fluid within the system were shown depending on the filling conditions of the hydrogen oxidation system. In addition, it was found that waste heat could be recovered by optimizing the temperature of the exhaust gas, flow rate, and pressure conditions within the heat recovery system and securing hot water above 40 ℃ by utilizing the exhaust gas oxidation heat source above 300 ℃. Through this study, it was possible to confirm the potential of utilizing hydrogen processes, which are applied in small to medium-sized systems such as hydrogen fuel cells, as a safety system by evaluating them at a pilot scale. Additionally, it could be a safety guideline for responding to unexpected hydrogen safety accidents through further pilot-scale studies.