• Journal of Sensor Science and Technology
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• v.10 no.2
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• pp.108-117
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• 2001

A sensor array with 10 discrete sensors integrated on a substrate w3s developed for discriminating the kinds and quantities of inflammable gases, like butane, propane, methane, LPG, carbon monoxide. The sensor array consisted of 10 metal oxide semiconductor gas sensors using the nano-sized $SnO_2$ as base material and had differentiated sensitivity patterns to specific gas. The sensor array was designed with uniform thermal distribution and had also high sensitivity and good reproductivity to low gas concentration through nano-sized sensing materials with different additives. By using the sensing patterns of the sensor array at $400^{\circ}C$, we could reliably discriminate the kinds and quantities of the tested inflammable gases under the lower explosion limit through the principal component analysis(PCA).

• Resources Recycling
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• v.24 no.2
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• pp.29-35
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• 2015

A feasibility test was carried out for upcycling of waste jelly-filled communication cables together with the development of environmentally friendly processes and equipments. High pressure water injection is proved to be an exceptionally environmentally friendly and highly efficient mechanical process. A batch-type cable barking equipment is designed and built on the basis of computational fluid dynamics modelling. It is optimized in terms of energy consumption and productivity with very high copper recovery of 99.5%. Copper nano-powder is prepared by an electrical wire explosion in ethanol media in order to improve the value of final products, and the preliminary economical assessment is also conducted.

• Journal of the Korean Institute of Gas
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• v.19 no.4
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• pp.15-21
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• 2015

Looking at the large and small fire, explosion, or release accidents that occurred recently, we can see that the accident of subcontractor workers has been increased in the contractor workplace while a harmful or dangerous maintenance works. In this study, the actual status of subcontractor's safety management was examined by using the questionnaire to the contractor who submitted the process safety report. In order to improve the safety management of subcontractors, the responsibility and rational role-sharing between the contractors and subcontractors were reviewed. Also, Providing safety and health information and worker protection measures during maintenance were investigated. The results of this study can be used to help strengthen and improvement safety management of the subcontractor at the time of a hazardous or dangerous works. In addition, it will be utilized to reduce industrial accidents and to build mutual cooperation relationship between contractor and subcontractor.

• Journal of Magnetics
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• v.16 no.1
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• pp.36-41
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• 2011

If gas is leaking out of gas pipelines, it could cause a huge explosion. Accordingly, it is important to ensure the integrity of gas pipelines. Traditionally, over the years, gas-operating companies have used the ILI system, which is based on axial magnetic flux leakage (MFL), to inspect the gas pipelines. Relatively, there is a low probability of detection (POD) for the axial defects with the axial MFL-based ILI. To prevent the buried pipeline from corrosion, it requires a protective coating. In addition to the potential damage to the coating by environmental factors and external forces, there could be defects on the damaged coating area. Thus, it is essential that nondestructive evaluation methods for detecting axial defects (axial cracks, axial groove) and damaged coating be developed. In this study, an electromagnetic acoustic transducer (EMAT) sensor was designed and fabricated for detecting axial defects and coating disbondment. In order to validate the performances of the developed EMAT sensor, experiments were performed with specimens from axial cracks, axial grooves, and coating disbondment. The experimental results showed that the developed EMAT sensor could detect not only the axial cracks (minimum 5% depth of wall thickness) and axial grooves (minimum 10% depth of wall thickness), but also the coating disbondment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.8
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• pp.996-1003
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• 2019

The undergrounding of diverse ground facilities has led to a decrease in issues, such as foul smell of water supply systems and wastewater, a fall of telephone poles, electromagnetic waves and breaking of wires caused by a railway work. On the other hand, there are new issues, including a fall accident, explosion affected by flammable gas, a choking accident by harmful gas and a lack of oxygen concentration, a fire coming from high-tension wire heating and flooding in the manhole. Besides, these issues damage the civil society and are an anxiety to public safety. Therefore, this paper is focused on a smart manhole device for stable communication environments inside and outside the manhole and wireless communication with various devices for managing facilities in the manhole, and aims to make a contribution to public safety by suggesting a direction of future underground facility management.

• Journal of Sensor Science and Technology
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• v.33 no.5
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• pp.259-264
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• 2024

The early detection of hydrogen gas leaks is crucial because of their high explosion risk. Current oxide-semiconductor-based hydrogen sensors are reliant on electrical circuits that may fail during accidents and require high temperatures, thereby raising safety concerns. Thus, there is an urgent need for the development of simpler and more intuitive sensors that can operate at room temperature. This study proposed a hydrogen sensor based on Pd-MoO₃ nanowires. The sensor exhibited a visible color change upon exposure to hydrogen at room temperature. The Pd-MoO₃ nanowires were synthesized by decorating the surface of hydrothermally produced MoO₃ nanowires with 1-5 wt.% Pd. Upon exposure to 5% hydrogen gas at room temperature, all Pd-MoO₃ nanowires exhibited distinct color changes (∆E). In particular, the MoO₃ nanowires with 3 wt.% Pd (3Pd-MoO₃) yielded an exceptionally high ∆E value of over 15 within 10 min. Further, the 3Pd-MoO₃ nanowires exhibited a noticeable color change (∆E > 1.6) within 2 min, demonstrating their potential for highly sensitive and rapid hydrogen detection. The outstanding color change of the 3Pd-MoO₃ nanowires was attributed to valence changes in both Mo (Mo⁶⁺ and Mo⁵⁺) and Pd (Pd²⁺ and Pd⁰) upon exposure to hydrogen.

• Journal of the Korean Institute of Gas
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• v.18 no.3
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• pp.38-43
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• 2014

This paper is to analyze and study the failure examples of fire by inflammables and electric contact faulty in interior of vehicle. The first example, the driver used to air freshener that remove the air conditioner bad smell. He get out of a car. And then, he put it on the crash pad. Before long, a fire breaks out because of explosion solar radiation. The second example, the driver used in room of a car. It certified the fire by disconnection phenomenon happened the electric overload. The third example, the driver install the heat rays to warm his body, In the initial stages, it didn't seek the dangerous of fire during using a car to 5,000km. This heat rays become to down durability so that produced the electric overload in an instant. The fourth example, after the man smoked the cigarette on riding with rear seat, he put it on seat in vehicle no extinguishing the burning cigarette. It knew the fact that burnt to ashes a car by on well combustible paper. Thus, the driver must consider a countermeasure for minimize the fire production when he use the inflammable and install adding electric system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.129-136
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• 2020

A Cut Out Switch (COS) is used for line protection and pole transformer protection in power systems. The COS used to protect the pole transformer is installed on the power side of the pole transformer to protect the electric equipment from fault currents. The COS is composed largely of a body and a fuse holder, and when the fault current is energized, the element of the fuse link in the fuse holder is melted to block the fault current. The arc generated when the COS fuse link is blown causes fire and noise, causing discomfort to residents in the surrounding area, and the arc flame can cause secondary damage to the peripheral device. In this study, a current-limiting COS fuse with improved overcurrent blocking performance rather than explosion type was developed to solve the arc and noise problems during COS operation. The overcurrent breaking performance of the current-limiting COS improves the reliability by developing a striker and COS fuse bracket. In addition, this study aimed to verify the performance of the developed current-limiting COS fuse through a test at an authorized institution.

• Journal of Preventive Medicine and Public Health
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• v.1 no.1
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• pp.43-49
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• 1968

Epidemiological and statistical observations were made of fire hazards that occurred during the past 18 years, 1948 to 1965. Injury and mortality rates for all ages were computed chronologically. For the years of 1955, 1961 and 1965, all fire accidents were epidemiologically analysed to draw characteristic patterns in relation to the seasonal and 24 hour distribution, causes and sites of accidents etc.. Fire hazards observed herein are the categorys E 916 of the International Classification of Causes of Death, 1955, and includes all accidents caused by fire and explosion of combustible materials. The following conclusion was made: 1. The average number of annual deaths due to fire was 183 and the number of the in jured due to the same cause was 335. The mortality rate per 100,000 population was 0.8 and the ratio of injuries per death was 1.83. 2. The casually rate including both the dead and injured was 5.0 per 100,000 in Seoul, the highest among the provinces and followed by 3.4 in Cheju -Do, 2.1 in Kangwon-Do, 1.7 in Kyunggi-Do accordingly. The other provinces had a range of 0.6 to 1.2. 3. The monthly distribution of fro accidents showed that the winter months, December through February, had more frequent accidents, while the summer season, June through August had less. The 24 hour distribution of accidents showed more cases from 12:00 to 18:00 and less from 4:00 to 10:00 hours. 4. The per cent distribution of causes of accidents showed; 90.0% for careless, 10.0% for arson. The cause of carelessness was further breakdown into; 15.0% for kitchen fire places, 13.8% for fire playing, 9,4% for electrical heating and wires, 8.3% for fuels, 6.3% for matches, 5.2% for ash dumps and the remaining for others. 5. The accidents as classified by place revealed that 56.8% of the total occurred at the common dwelling houses, 11.3 at various industrial workshops, 9.3% at the street shops and the remaining at the miscellaneous places.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2003.04a
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• pp.35-35
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• 2003

)를 금속와이어에 인가하면 저항발열에 의해 와이어가 미세한 입자나 금속증기상태로 폭발하는 현상을 이용한 것으로 기상합성법에 속한다고 할 수 있다. 선폭법은 다른 제조법에 비해 공정이 간단하여 생산비용이 저렴하며, 원재료의 조성을 갖는 분말의 합성과 금속간화합물, 융점차이가 나는 재료의 합금화 등이 가능하다. 인가에너지의 크기와 폭발 시 분위기를 제어함으로써 분말의 평균크기와 분포 제어 또한 가능하다. 본 연구는 러시아의 우수한 기초기술을 바탕으로 Pb-Sn계 합금은 전기폭발법으로 극미세분말을 제조하였으며, 분말의 형상, 상 화학조성의 변화를 조사하였다. 본 실험에 사용된 Sn-Pb계(All-Union State Standard 1499-70, 0.53mm)합금와이어는 자동시스템(1-0.6Hz)에 의해 챔버안으로 공급되었다. 이 때 임계폭발 와이어 길이는 50-80nm으로 실험을 행하였다. 챔버 압력은 1.4~2.0atm으로 유지하였다. 제조된 분말의 특성은 XRD, XRPES, SEM등을 이용하여 분말의 형상과 상, 화학조성, 표면분석을 행하였으며 DSC, TGA, BET분석을 통하여 온도변화에 따른 금속분말의 열량변화, 질량변화, 비표면적을 측정하였다. 제조된 Sn-Pb계 분말은 모두 평균 입도 117nm~220nm의 구형형상이었다. 이때 합금분말의 조성은 51.17~63.21 at%Sn, 35.47~46.37 at%Pb로 나타났다. 와이어에 인가되는 비에너지(W/Wc)가 감소된에 EK라 표면층의 Pb함량이 증가함을 보였다. 이는 와이어 내부 저항의 감소로 인한 공정시간의 지연과 Sn, Pb의 확산계수 차이에 의한 것으로 사료된다. 열분석 결과, Sn~Pb계 화합물의 융점은 167~$169^{\circ}C$로 관찰되었으며, $10^{\circ}C$/min로 $920^{\circ}C$까지 승은 하였을 때 17.1~18 wt%의 질량증가를 보였다.TEX>계 나노복합분말이 얻어짐을 알 수 있었다. 이 때 X션 회절피크의 line broadening으로부터 복합분말의 Fe 명균 결정립 크기는 24nm로 초미세 결정럽의 분말합금이었다. 포화자화값은 볼밀처리에 따라 점점 증가하여 MA 30시간에는 20.3emu/g로 포화됨을 알 수 있었다. 또한 보자력 Hc는 MA초기단계에 350e로 매우 낮으나 30시간 후에는 Hc값이 2600e로 매우 큰 값을 나타내었다. 이것은 환원반응결과 초기에 생성된 Fe의 결정립이 비교적 크고 결정결함이 적으나 볼밀처리를 30시간까지 행하면 Fe 결정렵의 미세화 빛 strain 증가로 magnetic hardening이 일어나기 때문인 것으로 사료된다.길이가 50, 30cm인 압출재를 제조하였다. 열간압출한 후의 미세조직을 광학현미경으로 압출방향에 평행한 방향과 수직방향으로 관찰하였고, 열간 압출재 이방성을 검토하기 위하여 X선 회절분석을 실실하여 결정방위를 확인하였다. 전기 비저항 및 Seebeck 계수 측정을 위하여 각각 2$\times$2$\times$10$mm^3$ 그리고 5$\times$5$\times$10TEX>$mm^3$ 크기의 시편을 준비하였다.준비하였다.전류를 구성하는 주요 입자의 에너지 영역(75~l13keV)에서 가장 높은(0.80) 상관계수를 기록했다. 넷째, 회복기 중에 일어나는 입자들의 유입은 자기폭풍의 지속시간을 연장시키는 경향을 보이며 큰 자기폭풍일수록 현저했다. 주상에서 관측된 이러한 특성은 서브스톰 확장기 활동이 자기폭풍의 발달과 밀접한 관계가 있음을 시사한다.se that were all low in two aspects, named "the Nonsignificant group". And the issues were high risk perception in general setting and lo