• 비파괴검사학회지
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• 제27권6호
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• pp.556-562
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• 2007

This paper presents the use of a novel fiber optic accelerometer system to monitor ambient vibration (both wind-induced one and vehicle-induced) of a real bridge structure. This sensor system integrates the $Moir\'{e}$ fringe phenomenon with fiber optics to achieve accurate and reliable measurements. A low-cost signal processing unit implements unique algorithms to further enhance the resolution and increase the dynamic bandwidth of the sensors. The fiber optic accelerometer has two major benefits in using this fiber optic accelerometer system for monitoring civil engineering structures. One is its immunity to electromagnetic (EM) interference making it suitable for difficult applications in such environments involving strong EM fields, electrical spark-induced explosion risks, and cabling problems, prohibiting the use of conventional electromagnetic accelerometers. The other is its ability to measure both low- and high-amplitude vibrations with a constantly high resolution without pre-setting a gain level, as usually required in a conventional accelerometer. The second benefit makes the sensor system particularly useful for real-time measurement of both ambient vibration (that is often used for structural health monitoring) and strong motion such as earthquake. Especially, the semi-strong motion and the small ambient one are successfully simulated and measured by using the new fiber optic accelerometer in the experiment of the structural health monitoring of a real bridge.

• 한국추진공학회지
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• 제23권2호
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• pp.87-94
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• 2019

액체로켓 추진기관 시험설비는 시험대상체가 상위 시스템에 장착되었을 때의 인터페이스 조건을 모사하여야 하며, 시험 시 파손이 발생할 수 있는 개발품의 특성상, 안전하게 시험이 이루어질 수 있게 구축되어야 한다. 이를 위해 추진기관 시험설비 기반시설은 안정적인 연소가 이루어지고 사고 시에도 안전이 보장되도록 구축되어야 한다. 본 논문에서는 액체로켓 엔진 추진기관 시험설비 기반시설의 구축 및 운영 시 고려해야 할 사항에 대해, 토목/건축, 시험 스탠드, 설비의 배치, 타 설비와의 운영 조합 및 공동구, 소화설비, 전력설비 측면에서 고찰하였다.

• 한국가스학회지
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• 제24권6호
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• pp.83-90
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• 2020

본 연구는 국제공동 연구로 만들어진 HyKoRAM 프로그램을 이용하여 위험성평가를 진행하였다. 수소충전소 내 압축기, 저장탱크, 수소 배관 등 주요 시설 및 구성품의 설계 사양, 실증 단지 주변의 환경 조건 등을 반영한 대안의 사고 시나리오와 시설에서 발생할 수 있는 최악의 시나리오에 기반하여 위험성 평가를 실시하였다. 수소충전소의 잠재 위험을 확인하여 수소 저장 탱크, 처리 시설, 저장 시설 등에서 발생 가능한 최악의 누출, 화재, 폭발, 사고 시나리오를 도출하고, 사고 발생 가능성과 인체, 주변 시설 피해 영향 분석을 하여 안전성을 검토하고자 한다.

• Journal of Ceramic Processing Research
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• 제13권spc2호
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• pp.308-311
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• 2012

A wide range of possible hazards existing in thermal batteries are mainly caused by thermal runaway, which results in overheating or explosion in extreme case. Battery separators ensure the separation between two electrodes and the retention of ion-conductive electrolytes. Thermal runaways in thermal batteries can be significantly reduced by the adoption of these separators. The high operating temperature and the violent reactivity in thermal batteries, however, have limited the introduction of conventional separators. As a substitute for separators, MgO powders have been mostly used as a binder to hold molten salt electrolyte. During recent decades the fabrication technology of ceramic fiber, which has excellent mechanical strength and chemical stability, has undergone significant improvement. In this study we adopted wet-laid nonwoven paper making method instead of the electrospinning method which is costly and troublesome to produce in volume. Polymeric precursor can readily be coated on the surface of wet-laid ceramic paper, and be formed into ceramic film after heat treatment. The mechanical strength and the thermo-chemical stability as well as the wetting behaviors of ceramic separators with various molten salts were investigated to be applicable to thermal batteries. Due to their excellent chemical, mechanical, and electrical properties, wet-laid nonwoven separators made from ceramic fibers have revealed positive possibility as new separators for thermal batteries which operate at high temperature with no conspicuous sign of a short circuit and corrosion.

• 에너지공학
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• 제25권1호
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• pp.145-152
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• 2016

가스사고 연감에 의하면 최근 가연성 및 독성 가스로 인한 사고가 끊임없이 발생하고 있다. 이러한 사고를 예방하기 위하여 위험지역에서도 안전하게 가스 누출여부를 검사할 수 있는 검지기를 개발하고자 한다. 따라서 본 논문에서는 적외선 가스센서의 응답특성에 근사하는 방정식을 선형회귀를 이용하여 도출하였다. 선형회귀방정식을 통해 도출된 결과를 Neville 반복 보간법을 활용하여 알고리즘을 제안하였다. 또한, 제안한 알고리즘을 시판중인 가연성 가스누출검지기와 한국가스안전공사에서 제조한 7종의 표준가스를 이용하여 시험을 한 결과 성능이 향상될 수 있음을 확인하였다. 향후 경년변화, 온 습도 조건에 따른 성능변화를 분석하고, 방폭구조를 적용한 회로를 적용함으로서 신뢰성과 안정성을 향상시키고자 한다.

• 전기학회논문지
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• 제60권6호
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• pp.1163-1168
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• 2011

Most transformers use insulating and cooling fluids derived from petroleum crude oil, but mineral oil has some possibility of environmental pollution and fire with explosion. vegetable oil fluids extracted from seed has superior biodegradation and fire-resistant properties including an exceptionally high fire point enhancing fire safety. In this study, it is aimed at the practicality of substituting natural ester dielectric fluid for mineral oil in liquid insulation system of transformers. As a rise in coil winding temperature has a direct influence on transformer life time, it is important to evaluate the temperature rise of coil winding in vegetable oil in comparison with mineral oil. Four transformers for the test are designed with 10KVA, 13.2KV, one phase unit. The temperature are directly measured in insulating oil of these transformers with the two sorts of natural ester and mineral oil dielectric fluid respectively. Experiment for aging carry out two means. First means remained $120^{\circ}C$ that transformer of mineral oil were operated at 185% load. Second means is that insulating oils of two natural ester and mineral oil were aged by thermal cycles repeating from $30^{\circ}C$ to $120^{\circ}C$. For the heating, Transformers were operated at 185% load. For the cooling, cooling system was operated in the chamber. Samples were analyzed at 42, 63, 93, 143, 190, 240 300cycles. Analysis contents are dielectric strength, total acid value. Mineral oils compared results of first means with results of second means. And compared two sort natural esters respectively with mineral oil in second means.

• 전기학회논문지P
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• 제65권1호
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• pp.31-40
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• 2016

The purpose of this study is to dimensionally examine the factors of policy changes by applying the ACMS model to KEPCO's structural reorganization privatization policies and study its implications. As a result of the analysis, among the external variables that affect as a financial source or restriction to advocates, all areas except for the difference in opinion of the people as well as policy decision and effects of other subordinate systems were shown to be in an advantageous condition acting as a financial source to advocates of structural reorganization privatization. On the other hand, advocates affected by the external variables share a certain belief system in which the advocates of privatization share the justification of profitability while the advocates of collectivization share the justification of publicness. In these flows, the announcement of the privatization plan of public enterprises of the committee of planning and budgeting acts as a matter of contact which opens the windows for policy changes, and this window goes through ignition, explosion, and fixation which causes fierce interactions among advocates of both sides. Eventually, in accordance with the contents of excluding electricity(KEPCO) from the list for privatization the window for policy changes has closed and things have changed to a transitional KEPCO privatization policy. Based on this, the first implication is that non-official participants such as the people, social organizations, labor unions, etc. influence policy changes more than they did before. Secondly, in the process of policy changes, there is an order of boundary even in the fierce interactions between each advocate. Thirdly, specific variables can play various roles in complex policy phenomenon. Fourthly, a logical analysis using the ACMS model is possible in Korea as well. Fifthly, as a result of analyzing the change process of the KEPCO structural reorganization privatization policy through the ACMS model, not all matched with the main research results implied by the ACMS model.

• 한국전기전자재료학회논문지
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• 제29권10호
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• pp.652-658
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• 2016

Thermal batteries use inorganic salt as electrolyte, which is inactive at room temperature. As soon as heat pellets are fired by an igniter, all the solid electrolytes are instantly melted into excellent ionic conductors. However, the abnormal heat generation by the igniter flame or heat pellets causes the thermal decomposition of the electrode and the melting of the anode, eventually leading to a thermal runaway, which results in overheating or explosion. The thermal runaway can be significantly reduced by the adoption of $Zr/BaCrO_4$ heat papers. In this study, the heat papers with various ratios of fuel (Zr) and oxidizer ($BaCrO_4$) were prepared by the paper-making process. We have investigated the calorimetric value, burning rate, and ignition sensitivity. The ignition test of heat pellets and the discharge test of thermal batteries were also carried out. At the composition of 40 wt.% of Zr, the heat papers showed the highest specific calorimetric value and burning rate. As a result, $Zr/BaCrO_4$ heat paper made by the paper-making process has shown the applicability for thermal batteries.

• 한국가스학회지
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• 제20권6호
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• pp.89-94
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• 2016

국내 캠핑문화의 확산과 국민 여가문화의 선진화에 따라 야영인구 및 야영장의 수가 급속히 증가하고 있다. 야영인구 및 야영장 수의 빠른 증가로 인하여 안전사고 또한 급격히 증가하고 있어서 효율적인 안전관리 대책이 필요하다. 특히, 과열에 의한 부탄캔의 폭발, 밀폐된 공간에서 연소기 사용에 의한 CO 중독 등의 가스사고가 증가하고 있으므로 사고를 예방하는데 집중할 필요가 있다. 본 연구에서는 취사장, 샤워장 등 야영장 시설에서 사용되는 액화석유가스 시설과 주요 캠핑용품의 사용실태 및 위험요소를 분석하고 효과적인 안전관리 방안 도출을 위한 방향을 제시하고자 하였다. 본 연구의 결과를 통해 국내 야영장 내 액화석유가스 사용 상 안전 관리 효율성 증대에 도움이 될 수 있을 것으로 기대한다.

• 융합신호처리학회논문지
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• 제25권1호
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• pp.46-51
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• 2024

드론은 최초 군사용으로 사용되었으나 최근들어 사용범위가 확대됨에 따라 농업, 서비스, 물류, 레져용 등 다양한 산업분야에서 폭넓게 사용되어지고 있는 추세이다. 리튬폴리머 배터리는 경량이면서 효율이 우수하여 드론의 전원공급 장치로 주로 사용되고 있다. 이에따라 드론에 안정적인 전원공급을 위하여 경량이면서 에너지 밀도가 높은 리튬폴리머 배터리의 필요성이 커지게 되었다. 그러나 리튬폴리머 배터리는 과충전, 과방전, 단락 등의 이유로 발화 및 폭발로 이어질 수 있어 반드시 보호회로를 탑제하여 사용해야한다. 보호회로는 리튬폴리머 배터리의 전압을 모니터링하는 제어IC인 보호 IC와 과방전시 스위치 역할을 하는 듀얼 N-channel MOSFET 등으로 구성되어있다. 따라서 본 논문은 배터리 보호 IC와 스위치 역학을 하는 MOSFET의 반도체 Die Chip을 이용하여 원칩 패키지 IC형태로 구현하였다. 원칩 패키지 IC로 구현하면 기존 부품 대비 최소 67%의 절감효과를 갖게된다.