• Proceedings of the KIEE Conference
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• 2007.04b
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• pp.88-90
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• 2007

본 논문에서는 배선용 차단기 단자와 전선간의 접속결함에 의한 아크발생 및 화재위험성을 분석하였다. 실험 및 분석에 사용된 배선용 차단기는 단상 2선식의 국내외 제품으로 외형분석결과 단자구조는 제품마다 상이하였으며, 단자와 전선간의 접촉저항 측정결과 국내 제품은 접속방식에 따라 접촉저항의 편차가 컸다. 배선용 차단기 단자와 전선간 접속결함에 의한 접촉불량 발생시 단자구조에 따른 아크 및 화염의 특성 실험의 부하조건으로는 저항부하를 사용하였으며, 가진기의 축에 배선용차단기를 설치하여 진동에 의한 영향을 받도록 하였다. 인가시간은 10[분]으로 하였으며, 접촉불량이 진전됨에 따라 배선용 차단기 단자에 아크가 지속적으로 발생하였다. 대략 수분이 경과한 후 차단기가 차단되는 경우도 있었으며, 차단되지 않는 경우도 있었다. 또한 4개사의 제품 중 1개사의 제품은 접속단자 주변 절연재료로 아크에 의한 화염전이가 용이하였다.

• Journal of the Korea Concrete Institute
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• v.18 no.4 s.94
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• pp.559-568
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• 2006

The purpose of this study is to evaluate the mechanical performance and fire resistance of wet-mixed high strength sprayed polymer-modified mortar in order to protect tunnel lining system which are in the event of fire disaster. Since the current commercial fire-resistant materials reproduce the low strength issue of mortar, this study aims to provide an enhanced fire-resistant mortar with a proper strength. Normally, a large temperature gradient phenomenon arise in the vicinity of free surfaces which are fully exposed in the event of persistent flame. Thereby, the determination of optimal cover depth of wet-mixed high strength sprayed polymer-mortar(WHSPM) is important for fire-resistance of tunnel lining system. With comparison of current commercial fire-resistance materials and WHSPM, the experimental result of WHSPM shows the better fire-resistant performance than the others. In addition, the cover limitation should be controlled by minimum 4cm depth in order to avoid fire-induced damage.

• Fire Science and Engineering
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• v.19 no.2 s.58
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• pp.75-80
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• 2005

This dissertation is about the development of PTC(Positive Temperature Coefficient) thermistor by composition method. A multilayer-type PTC samples were fabricated under optimal conditions after setting the experimental composition equation as $(0.90Ba+0.05Sr+0.05Ca)TiO_3+0.01TiO_3+0.01SiO_2+0.0008MnO_2+0.0018Nb_2O_5$ and their testing results were analyzed. The fabrication method of SMD(Surface Mounted Device) multilayer -type sample based on the composition ratio has the advantages in lowering its resistivity at room temperature, considerably, and increasing maximum current level, as needed. Although there is a disadvantage of peak resistivity drop by the multilayer, causing the increasement of thermal capacity. and thereby, increasing the switching delay time, a high applying voltage can increase the peak resistivity and shorten the switching delay time. The voltage-current characteristic showed that the more multilayers increased the initial maximum current and the transition voltage that increased the resistivity abruptly according to the curie point. The element it could be applied with the sensor for the fire detector.

• Fire Science and Engineering
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• v.16 no.4
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• pp.15-19
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• 2002

This dissertation is about the development of $BaTiO_3$-type PTC(Positive Temperature Coefficient) thermistor by composition method. A multilayer-type PTC samples were fabricated under optimal conditions after setting the experimental composition equation as ($Ba_{0.95-x}$S $r_{0.05}$$Ca_{x}$ )$TiO_3$-$0.01TiO_2$-$0.01SiO_2$-$\alpha$$MnCO_3$-$\beta$N $b_2$ $O_{5}$.) and their testing results were analyzed. The optimal sin-tering and cooling temperatures were 13$50^{\circ}C$ for two hours and $100^{\circ}C$/h for an hour, respectively; By composing Ca and Mn, dopants to lower the resistivity at room temperature, and Nb, a dopant to raise peak resistivity(Ca:5 mol%, Mn:0.08 mol%, Nb:0.18 mol%), appropriately, a PTC thermistor, having the characteristics of relatively low resistivity at room temperature and high peak resistivity and a good temperature coefficient, has been developed. And we find that it is possible of application for fire detection sensor.r.r.

• Tunnel and Underground Space
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• v.32 no.6
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• pp.363-372
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• 2022

Precast concrete is an effective method to increase the construction quality and construction speed by optimizing and making the manufacturing conditions similar. In order to more effectively produce a fireproof material-integrated precast duct slab, the purpose of this study was to determine whether the fire resistance performance of the fireproof layer is maintained when a method of increasing the curing rate using a hardening accelerator is used. As a result of performing a fire resistance performance test on specimens classified according to whether or not the hardening accelerator was included, increase of temperature inside the specimen was high in the specimens using the hardening accelerator, and the section loss of the fireproof layer occurred locally on the surface exposed to fire heating. In conclusion, it is judged that the fireproof layer in the case where the strength at 3th day of age is gained within 1 day curing age using a hardening accelerator does not guarantee sufficient fire resistance performance in the conditions used in this study.

• Fire Science and Engineering
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• v.21 no.4
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• pp.65-71
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• 2007

This paper is studied on a protective control system for electrical fire and electrical faults by using electrical and thermal characteristics of PTC thermistor. The PTC thermistor has characteristic or positive resistivity temperature coefficient according to the temperature variation, which is construction of a regular square and cube demarcation with $BaTiO_3$ Ceramics of positive temperature coefficient. Also PTC thermistor shows the phenomenon which is rapidly increased in the resistivity if the temperature is increased over Curie temperature point. This paper is proposed on a protective control system used PTC thermistor which is protected from electrical fire due to electric short circuit faults or overload faults. Some experimental results of the proposed electric safety control apparatus are confirmed to the validity of the analytical results.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2013.04a
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• pp.56-57
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• 2013

Plug-In MCCB는 전원부의 연결 단자가 없으며, 차단기 후면에 설치된 하우징 형태(housing type)의 플러그 유닛으로 부스바에 원터치(one touch) 설치 및 분리 등이 가능하다. 그러므로 차단기의 교체 시간이 짧고, 전원 복구가 신속하여 설비의 효율적 운용에 기여할 수 있다. 차단기의 후면에 있는 플러그 유닛이 동 부스바에 연결되었을 때 저항 특성을 초저항측정기(Resistance Tester)로 분석하였다. 3상 3선식 플러그인 배선용차단기를 동 부스바에 설치했을 때 R-phase과 플러그 단자 사이의 접촉 저항은 $0.51m{\Omega}$으로 확인되었다. 즉, 개발된 Plug-In MCCB를 이용하여 부스바에 설치할 때 접촉(속)부의 전기적 특성이 우수한 것을 확인할 수 있었다.

• Proceedings of the KIEE Conference
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• 2009.04a
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• pp.198-199
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• 2009

산업이 발달함에 따라 전기는 우리 일상 생활에 있어 없어서는 안 될 중요한 요소이나 그 사용에 따른 화재 위험성 또한 날로 증가하는 추세이다. 특히 전기 화재의 경우 전기용품 사용에 있어 그 사고를 미리 감지하기 어려워 사고 위험성에 대하여 무방비 상태가 된다. 특히 우리나라의 경우 전체 화재 건수 중 전기 화재가 차지하는 비율은 30%이상으로 일본, 미국 등 선진국에 비해 높아 화재 원으로서 전기 화재 예방에 대한 그 중요성 대두된다 본 논문에서는 전기화재 발화 원인 중 단자대 접촉부 접촉 불량으로 야기된 과열에 의한 화재를 예방하기 위하여 접촉부 접촉 저항을 검출 하는 시스템에 대하여 알고리즘 개발 및 설계 하였다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.2086-2087
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• 2007

산업이 발달함에 따라 전기는 우리 일상 생활에 있어 없어서는 않 될 중요한 요소이나 그 사용에 따른 화재 위험성 또한 날로 증가하는 추세이다. 특히 전기 화재의 경우 전기는 시각적인 흐름을 볼 수가 없어 전기용품 사용에 있어 그 사고를 미리 감지하기 어려워 사고 위험성에 대하여 무방비 상태가 된다. 특히 우리나라의 경우 전체 화재 건수 중 전기 화재가 차지하는 비율은 30%이상으로 일본, 미국등 선진국에 비해 높아 화재원으로서 전기 화재예방에 대한 그 중요성 대두된다. 본 논문에서는 전기화재 발화 원인 중 단자대 접촉부 접촉 불량으로 야기된 과열에 의한 화재를 예방하기 위하여 접촉부 접촉 저항을 검출 하는 시스템에 대하여 알고리즘 개발 및 설계 하였다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.3
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• pp.301-310
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• 2013

Jet fans are installed in road tunnels in order to maintain critical velocity when fire occurs. Generally the number of jet fans against fire are calculated by considering critical velocity and flow resistance by wall friction, vehicle drag force, thermal buoyance force and natural wind. In domestic case, thermal buoyance force is not considered in estimating the number of jet fans. So, in this study, we investigated the pressure loss due to the thermal buoyance force induced by tunnel air temperature rise and the impact of thermal buoyance force on the number of jet fans by the numerical fire simulation for the tunnel length(500, 750, 1000, 1500, 2000, 3500m) and grade (-1.0, -1.5, -2.0%). Considering the thermal buoyance force, number of jet fans have to be increased. Especially in the case of 100MW of heat release rate, the pressure loss due to thermal buoyance force exceed the maximum pressure loss due to vehicle drag resistance, so it is analyzed that number of 2~11 jet fans are needed additionally than current design criteria. Thus, in case of estimating the number of jet fans, it must be considered of thermal buoyance force induced tunnel air temperature rise by fire.