• Journal of the Korean Institute of Gas
• /
• v.15 no.3
• /
• pp.58-66
• /
• 2011

This study presents the behavior characteristics of buried three-layered pipeline subjected to pile driving loads. The analysis considered the driving energy caused by 7 tonf of ram weight and 1.2m of stroke. Also the distance from vibration resource to pipeline varies in 5m to 30m. The vibration velocity and stress are investigated at the center of pipeline in longitudinal direction. In the same cover depth, attenuation ratio of vibration velocity and von Mises stresses for distance increment has shown a decreasing trend. The maximum stress occurs at the top and bottom for the inner pipe, however, an irregular stress distribution is found for the outer pipe.

• Journal of the Korean Institute of Gas
• /
• v.15 no.4
• /
• pp.15-20
• /
• 2011

This study presents the behavior characteristics of buried three-layered pipeline subjected to pile driving loads corresponding to its cover depth. The analysis considered the driving energy caused by 7 tonf of ram weight and 1.2m of stroke with 20m distance from buried pipeline for all the analysis cases. A cover depth of pipe is varied 0.6m to 3.8m for this research. Vibration Velocity and stress are investigated at the center section in longitudinal direction. With same distance from pile, attenuation ratio of vibration velocity for increment of cover depth has shown an increasing trend. Also, Stress attenuation ratio of inner pipe is increased with cover depth.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.23 no.4
• /
• pp.152-158
• /
• 2019

Measure the type and content of VOCs for A-company epoxy coating and B-company floor coating(Type A, B), which are used as flooring materials for parking lots. Than the VOCs used gas detectors to measure gas emissions, assuming the worst environment to reduce errors in external environments in the formaldehyde, toluene and xylene harmful to workers and tenants. As a result, A-company epoxy coating has the largest amount of VOCs, and compared to A-company epoxy coating, B-company floor coating of A type represented about 79% less and B type about 96% less. In addition, A-company epoxy coating was also the highest in gas emission measurement for formaldehyde, toluene and xylene using gas detector after 1 hour and 8 hours in closed environment conditions. B-company floor coating A type was less than A-company epoxy coating, which was about 42.3% less measured. And type B satisfied all TWA even in closed environment conditions.

• KOREAN ASSOCIATION OF OCCUPATIONAL HEALTH NURSES
• /
• v.8 no.2 s.28
• /
• pp.10-18
• /
• 2001

우리나라 대기오염의 수준은 지난 90년대 초반 이후 아황산가스와 총부유분진의 농도가 감소하고, 대신 오존과 이산화질소의 농도가 증가하면서 점차 다른 선진국에서 경험하는 대기오염현황을 보이고 있다. 한편 PM10과 PM2.5와 같은 미세분진의 경우 그 측정기간이 짧고 자료가 제한적이지만, 일부 지역에서 증가추세를 보이고 있으며, 그 수준을 비교하였을 때 현재 선진국에서 책정한 미세분진의 규제농도를 훨씬 상회하는 것으로 판단된다. 대기오염으로 인한 건강영향으로는 급성으로 고농도에 수 시간에서 수 일 동안 노출되는 경우 폐기능의 저하, 심박동의 변화, 그리고 신체내 염증물질의 증가 등 인체 기능의 변화가 보고되고 있으며, 기존에 폐장질환이나 심혈관질환을 앓고 있는 사람들의 경우 증세의 악화와 의료이용의 증가 등을 경험하거나 더 나아가 사망에 이르러 수명이 단축되는 것이 보고되고 있다. 급성노출의 경우 미세분진 PM10 10 $\mu$m/m3 당 전체 사망률이 0.5-1$\%$ 가량 증가하는 것으로 보고되며, 만성노출을 조사한 코호트 연구에 근거하는 경우 대기오염에 노출되는 전체 인구에 있어 PM2.5 1 $\mu$m/m3 당 1개월의 수명이 단축되는 것으로 추정되고 있다. 아직 대기오염으로 인한 건강영향의 기전이 전부 밝혀진 것은 아니지만, 일부 연구에서 대기오염물질 중에서 전이금속의 역할이 보고되고 있으며, 대기오염에 노출되면서 기관지, 폐포 및 혈액 등에서 염증매개물질의 분비 및 확산 그리고 심장을 비롯한 각 장기 기능의 변화가 보고되고 있다. 한편 이러한 변화들이 증세와 건강상의 비가역적 변화를 야기하는데 있어 대기오염 수준의 역치는 없는 것으로 판단되고 있다. 이러한 대기오염의 영향에 대한 개인수준의 해결책으로서는 자동차 사용의 절제 및 개인적인 쓰레기 소각의 자제 등 오염원 발생의 감소와 함께 대기오염 수준에 따른 증세 및 투약의 적절한 조절과 신체 활동의 조절을 통하여 오염원을 회피하는 것이 강조되어야 하며, 또한 흡연 특히 실내흡연의 금지와 실내 주방기구 및 난방기구의 관리 등이 구체적으로 제시될 수 있다. 마지막으로 대기오염물질들이 신체에 들어와 산화제로 작용하는 만큼, 식품을 통한 항산화제의 섭취가 일반적인 건강관리 수준에서라도 반드시 강조되어야 할 것이다.

• Fire Science and Engineering
• /
• v.15 no.3
• /
• pp.7-13
• /
• 2001

In this paper, we had analyzed comsbustion gases according to pyrolysis $600^{\circ}c$, $800^{\circ}c$ and $1000^{\circ}c$ for polymeric material using a GASTEC colorimetric gas detector tube in order to combustion gases toxicity evaluation for flame retardant untreated ply wood, flame retardant treated ply wood, flexible polyvinyl chloride and flexible polyurethane foam of polymeric material. As a result, comsbustion gases producted from small specimens of polymeric material had reached fatal to man at a 30 minute exposure time that had possesed toxicity index. Toxicity index at pyrolysis $800^{\circ}c$ of flexible polyvinyl chloride was 31.74. Flexible polyvinyl chloride was the highest toxicity index of flame retardant untreated ply wood, flame retardant treated ply wood, flexible polyvinyl chloride and flexible polyurethane foam. The comsbustion gases producted commonly no concern with pyrolysis temperature had analyzed carbon dioxide($CO_2$) and carbon monoxide(CO). Toxicity index had investigated differently according to pyrolysis temperature even a similar materal.

• Journal of Energy Engineering
• /
• v.22 no.4
• /
• pp.413-419
• /
• 2013

The present study used the MILD combustor, which has coaxial cylindrical tube. The outside tube of the MILD combustor corresponds to the exhaust gas passage and the inner side tube is the furnace passage. A numerical analysis was accomplished to elucidate the characteristics of exhaust gas entrainment toward the inner furnace with the changes of venturi nozzle geometrical parameters, nozzle position, nozzle gap between high pressure air nozzle and venturi nozzle, and with the change of high pressure nozzle inlet velocity. The entrainment flow rate for the case with the high pressure air nozzle attached at the exhaust gas wall has relatively small change with the change of nozzle gap. That for the case with the high pressure air nozzle exposed to the exhaust gas has monotonically increase with the change of nozzle gap. The flow rate ratio of entrainment flow rate has considerably increase tendency with relatively lower air inlet velocity, on the other hand, that with relatively higher air inlet velocity could be seen relatively small increase.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1995.05a
• /
• pp.525-530
• /
• 1995

최적 열수력 전산 코드인 CATHARE2 Vl.3u 코드를 이용하여 영광 3/4호기 midloop 운전중 잔열제거(RHR) 기능 상실사고를 해석하였다. 본 연구의 주된 목적은 사고시 계통에서 발생하는 열수력 현상의 이해 향상 및 증기발생기 열제거 능력 평가에 있다. 사고 복구 절차 관점에서 노심 비등, 노출 시점 및 계통압력 등이 중요한 인자이다. 본 계산 수행시 사용한 가정은 다음과 같다. 가) 초기 계통 수위는 고온관 중간에 위치하며 그 윗 부분은 질소 가스로 차 있다. 나) 3/4 인치 크기의 방출 밸브가 원자로 용기 상부 및 가압기 상부에 각각 설치되어 있으며, RHR 흡입구에 수위지시계가 설치되어 있다. 다) 증기발생기의 이차측은 U-튜브가 잠기도록 물로 차있다. 라) 두 증기발생기의 대기 방출 밸브(ADV)는 항상 열려 있어 사고시 이차측 압력을 대기압으로 유지하기에 충분하다. 사고는 원자로 정지 2일 후 발생하였다고 가정한다. 이와 같은 조건하에서 사고시 주된 계통 열제거 수단은 증기발생기 U-튜브내의 응축 작용이며 이는 전체 열제거량의 94%로 나타났다. 노심 비등 시점온 사고후∼300초 이후이며, 계통압력은 10,800초 이후에 최고 압력인 0.25MPa에 도달한 후 그 값을 계속 유지하고 있다. RHR 배관에 연결된 수위지 시계를 통해 10,200초 이후부터 냉각수가 방출되었다. 2개의 방출밸브 및 수위지시계를 통하여 방출된 유량에 근거하여 원자로 용기 냉각재 수위가 고온관 바닦까지 낮아지는 시점을 계산하면 사고 약 6.4 시간 이후가 된다.

• Journal of the Society of Disaster Information
• /
• v.10 no.3
• /
• pp.420-430
• /
• 2014

Firefighters performing disaster response activities such as Fire Suppression Rescue First Aid in fire are being exposed in various adverse factors, heat, smoke, toxic gases, emotional stress, biological toxic factors and physical overload by unnatural ergonomic posture required for firefighters. But so far, there is the study for this problem only separately. There is no study about comprehesive analysis of exposed adverse factors in fire-related disaster response activities and countermeasures. The purpose of this study is to contiribute to solving the health problems and prevention of accidents of firefighters by extracting hazardous agents in disaster such as fire and by proposing countermeasures. After analyzing circumstances such as fire-suppression, rescue first aid and life-environment, exposure factors of fire are derived and exposure status is suggested according to physical chemical biological psychological aspects. The countermeasure against the noise of the physical exposure factors are proposed. The countermeasures such as protective equipment and clean room in chemical factors, infection prevention education, vaccination and periodic check system in biological factors, PTSD alleviation booth and mentoring in psychological factors are proposed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.26 no.1
• /
• pp.39-46
• /
• 2015

In this paper, a gas sensor using a modified $90^{\circ}$ hybrid coupler structure with conducting polymer which operates at 2.4 GHz is represented. Conducting polymers are used to the gas sensing material in proposed sensors. The conducting polymer varies its electrical property, such as work function and conductivity corresponding to the certain gas. To verify this variation of electrical property of conducting polymer at microwave frequencies, the conducting polymer is incorporated with the $90^{\circ}$ hybrid coupler structure, and this proposed sensor operates as reflection type variable attenuator and variable phase shifter. The conducting polymer is employed as impedence-variable transmission lines that cause a impedance mismatching between the general transmission line and conducting polymer. The experiment was conducted with 100 ppm ethanol gas at temperature of $28^{\circ}C$ and relative humidity of 85 %. As a result, the amplitude deviation of $S_{21}$ is 0.13 dB and the frequency satisfying ${\angle}S_{21}=360^{\circ}$ is shifted about 2.875 MHz.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2009.10a
• /
• pp.339-341
• /
• 2009

Surge Protective Device(SPD) is installed by increasing information and communication equipments and home network equipments by individual home, and the amount of SPD used is increasing by revision industry regulations and strengthening equipotential grounding system. Parts of SPD installed in residential distribution board has ZnO varistor, voltage constraint type devices, but it is exposed to Temporary Overvoltage Characteristic. This thesis analyzes products through Thermal Stability test for SPD for general house and suggests the better method. As results of analysis, Gas Discharge Tube(GDT) to cut off from a leakage current and more than two kinds of safety devices to protect Thermal Runaway were needed.