• 한국가스학회지
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• 제22권6호
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• pp.8-15
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• 2018

플랜트 내 위험지역의 안전을 위해 작업자 중심의 안전관리가 필요하다. 최근 5년간 가스 사고의 원인은 시설 노후 및 장비고장 뿐만 아니라, 사용자의 취급부주의나 고의사고, 공급자 취급부주의 등 작업자의 행동에 밀접한 관련이 있다. 이와 같은 사고를 미연에 방지하기 위해서, 플랜트 내 위험지역에 대한 실시간 모니터링이 필요로 하다. 하지만 실시간 모니터링을 위해서 작업(근로)공간에 카메라 설치 시, 인권침해와 같은 문제가 발생한다. 이를 방지하기 위해서 작업자의 신원 노출이 적은 저해상도의 Infrared 카메라를 이용한다. 또한 실시간 모니터링 시, 사람이 아닌 CNN알고리즘을 이용하여 이미지 분석을 통하여 인권침해 문제를 예방한다.

• Tribology and Lubricants
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• 제36권6호
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• pp.307-314
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• 2020

In this paper, studies on application cases of machine condition monitoring using oil sensors are reviewed. Owing to rapid industrial advancements, maintenance strategies play a crucial role in reducing the cost of downtime and improving system reliability. Consequently, machine condition monitoring plays an important role in maintaining operation stability and extending the period of usage for various machines. Machine condition monitoring through oil analysis is an effective method for assessing a machine's condition and providing early warnings regarding a machine's breakdown or failure. Among the three prevalent methods, the online analysis method is predominantly employed because this method incorporates oil sensors in real-time and has several advantages (such as prevention of human errors). Wear debris sensors are widely employed for implementing machine condition monitoring through oil sensors. Furthermore, various types of oil sensors are used in different machines and systems. Integrated oil sensors that can measure various oil attributes by incorporating a single sensor are becoming popular. By monitoring wear debris, machine condition monitoring using oil sensors is implemented for engines, automotive transmission, tanks, armored vehicles, and construction equipment. Additionally, such monitoring systems are incorporated in aircrafts such as passenger airplanes, fighter airplanes, and helicopters. Such monitoring systems are also employed in chemical plants and power plants for managing overall safety. Furthermore, widespread application of oil condition diagnosis requires the development of diagnostic programs.

• KEPCO Journal on Electric Power and Energy
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• 제8권2호
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• pp.119-126
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• 2022

A growing number of gas-insulated transformers in underground power substations in urban areas are approaching 20 years of operation, the time when failures begin to occur. It is thus essential to prevent failure through accurate condition diagnosis of the given facility. Various solid insulation materials exist inside of the transformers, and the generated decomposition gas may differ for each gas-insulated equipment. In this study, a simulation system was designed to analyze the deterioration characteristics of SF₆ decomposition gas and insulation materials under the conditions of partial discharge and thermal fault for diagnosis of gas-insulated transformers. Degradation characteristics of the insulation materials was determined using an automatic viscometer and FT-IR. The analysis results showed that the pattern of decomposition gas generation under partial discharge and thermal fault was different. In particular, acetaldehyde was detected under a thermal fault in all types of insulation, but not under partial discharge or an arc condition. In addition, in the case of insulation materials, deterioration of the insulation itself rapidly progressed as the experimental temperature increased. It was confirmed that it was possible to diagnose the internal discharge or thermal fault occurrence of the transformer through the ratio and type of decomposition gas generated in the gas-insulated transformer.

• 한국초전도ㆍ저온공학회논문지
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• 제25권1호
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• pp.6-10
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• 2023

2 K superfluid helium cryogenic system is the crucial component of many large accelerators. When the cryogenic system is operating at 2K@3129Pa, many room-temperature parts are connected to superfluid helium via tubes. Air Leakage in these connections may lead to air contamination of the cryogenic system. Air contamination may cause equipment failure in cryogenic systems and, in extreme cases, render the entire accelerator system inoperable. Helium guard is a technique that guards against air contamination of these sub-atmospheric pressure connections in 2 K superfluid helium cryogenic system. This paper introduces a typical 2 K cryogenic distribution design for large accelerators, and make risk analysis of air contamination. Finally, the analysis of specific leakage points and detailed engineering design are presented, which may be used as a reference when designing of a 2 K superfluid helium cryogenic distribution system.

• 지질공학
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• 제21권3호
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• pp.221-230
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• 2011

암반비탈면의 활동에 의해 전방 도로부에 융기현상이 발생되었다. 국내의 대다수 비탈면은 암반으로 구성되어 있으므로 연구지역과 같이 암반비탈면 활동에 의한 도로 융기현상을 관찰하기는 쉽지 않다. 본 연구를 통해 구성암 풍화와 지질학적 약대 형성이 진행된 암반비탈면은 불연속면을 따른 기하학적인 붕괴보다는 전체 구성암의 원호활동 지배를 더 크게 받을 수 있음을 파악하였다. 또한, 수치해석을 통해 편암 등 이방성이 강한 암석이나 특정 방향의 불연속면이 비탈면의 안정성에 영향을 미칠 경우에는 연속체 해석에 편재절리모델을 혼합하여 해석을 수행하는 것이 암반비탈면의 연속체 해석 수행에 매우 유용함을 확인하였다. 현장조사와 안정해석 결과를 근거로 본 비탈면의 안정화를 위해 계단식옹벽과 앵커공법을 제안하였으며, 보강 완료 후에는 계측기를 설치하여 실시간 모니터링을 통해 적용 대책공법의 효과를 검증하였다.

• 한국항행학회논문지
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• 제22권3호
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• pp.179-188
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• 2018

항공전자 시스템의 개발할 때 항공 사고를 예방하기 위해서 SAE ARP4761 (민간 항공 시스템 및 장비 안전성 평가 프로세스 수행 방법 및 지침) 규격에 명시된 안전성 분석 및 평가를 수행한다. 안전성 분석은 시스템의 정상상태가 아닌 비정상상태에 대한 지식과 다른 규격들 간의 상호 연관성에 대한 지식이 요구된다. 때문에, 안전인증규격의 준수를 입증하는 자료를 자동으로 출력하는 도구가 필요하다. 본 연구는 규격의 안전성 분석 절차를 도식화하고, 안전 분석 CAD 도구들을 개별 절차에 적용하는 방법을 연구하였다. 예시 연구로서, ARP4761 부록의 여객기용 휠 제동 시스템 (WBS; wheel brake system)을 대상으로 ARP4761분석을 수행하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제38권1호
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• pp.86-91
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• 2014

조선해양 및 플랜트 분야에서의 전력계통 구성은 분산 배치된 각각의 발전모선을 전기적으로 연결하여 사용한다. 이러한 방식은 다중화 된 모선이라기보다는 육상에서의 계통 연계와 동일한 개념으로 인식하는 것이 적합할 것이다. 이는 발전모선의 추가로 인하여 모선의 단락용량 또한 비례적으로 증대되기 때문이다. 단락용량의 증가는 관련 제반 비용의 상승을 초래하고 전기적 고장 발생 시에 물리적으로 연결된 모선들이 일시에 대정전(Blackout)을 발생시킬 가능성도 높아진다. 이러한 문제점을 해결하기 위하여 본 논문에서는 한류 리액터가 적용된 조선해양 전력계통에서 발전모선을 위상구조(Bus Topology)에 따라 분류하고 고장 종류 별로 단락전류 해석을 수행하였으며 그 결과를 상호 비교하여 장단점을 제시하였다.

• Corrosion Science and Technology
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• 제15권4호
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• pp.182-188
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• 2016

Significant piping wall thinning caused by Flow-Accelerated Corrosion (FAC) and Erosion-Corrosion (EC) continues to occur, even after the Mihama Power Station unit 3 secondary pipe rupture in 2004, in which workers were seriously injured or died. Nuclear power plants in many countries have experienced FAC and EC-related cases in steam cycle piping systems. Korea has also experienced piping wall thinning cases including thinning in the downstream straight pipe of a check valve in a feedwater pump line, the downstream elbow of a control valve in a feedwater flow control line, and failure of the straight pipe downstream of an orifice in an auxiliary steam return line. Cause analyses were performed by reviewing thickness data using Ultrasonic Techniques (UT) and, Scanning Electron Microscope (SEM) images for the failed pipe, and numerical simulation results for FAC and EC cases in Korea Nuclear Power Plants. It was concluded that the main cause of wall thinning for the downstream pipe of a check valve is FAC caused by water vortex flow due to the internal flow shape of a check valve, the main cause of wall thinning for the downstream elbow of a control valve is FAC caused by a thickness difference with the upstream pipe, and the main cause of wall thinning for the downstream pipe of an orifice is FAC and EC caused by liquid droplets and vortex flow. In order to investigate more cases, additional analyses were performed with the review of a lot of thickness data for inspected pipes. The results showed that pipe wall thinning was also affected by the operating condition of upstream equipment. Management of FAC and EC based on these cases will focus on the downstream piping of abnormal or unusual operated equipment.

• 한국재료학회지
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• 제15권8호
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• pp.536-542
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• 2005

Recently European Council(EU) published the RoHS(restriction of the use of certain hazardous substances in electrical and electronic equipment) which is prohibit the use of Pb, Hg, Cd, $Cr^{+6}$, PBB or PBDE in the electrical and electronic equipments. So EU member States shall ensure that, from 1 July 2006, new electrical and electronic equipment put on the market does not contain 6 hazardous substances. The one of the most important in electronics manufacturing process is soldering. Soldering process use the chemical substances which are applied in fluxing and cleaning processes and it can generate the malfunction of electronics caused by corrosion in the fields conditions. Therefore this study researched on the polarization and Tafel properties of Sn40Pb and Sn3.0Ag0.5Cu(SAC) solder based on the electrochemical theory. We prepared SnPb specimens which was aged in $150^{\circ}C,\;180^{\circ}C$ for 15 minutes ana Sn3.0Ag0.5Cu specimens that was aged in $180^{\circ}C,\;220^{\circ}C$ for 10 minutes. Experimental polarization curves were measured in distilled ionized water and $3.5 wt\%$, 1 mole NaCl electrolyte of $40^{\circ}C$, pH 7.5. Ag/AgCl and graphite were utilized by reference and counter electrode, respectively. To observe the electrochemical reaction, polarization test was conducted from -250 mV to +250 mV. From the polarization curves that were composed of anodic and cathodic curves, we obtained Tafel slop, reversible electrode potential(Ecorr) and exchange current density(Icorr). In these results, corrosion rate for two specimen were compared Sn3.0Ag0.5Cu with SnPb solders

• 한국안전학회지
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• 제27권3호
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• pp.49-56
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• 2012

The purpose of this paper is to present a model for operating an emergency power system(EPS) that can secure a sufficient power supply used in case of a fire by analyzing the status of power supplies for emergency and firefighting operations. Investigations on the one of the causes of the operational failure of firefighting systems show evidence of EPS. Generally, when power to a building is interrupted, EPS supplies the emergency load(excepted firefighting load) first. When a power outage and a fire occur simultaneously, the EPS must be able to supply both the emergency load and the firefighting load, especially the firefighting load to the end. However, in order to save construction costs, emergency power generators in apartment, commercial, and business buildings can satisfy only one of the required loads. In cases like this, when a power outage and a fire occur simultaneously, there is a danger of firefighting equipment not operating due to insufficient power supply from the emergency generator. Therefore, an EPS must have a reserved firefighting power that can supply both the firefighting and the emergency load. Such EPS, when faced with a danger of an overload, will shut down the supply to all or part of the emergency load, thus securing a continuous power supply to the firefighting equipment. The generator power system with reserved firefighting power (RFP) will also have an indicator to show that the selective control is being used. General power generation systems for emergency load and firefighting load were found to have a demand factor of 50-60% with a lump. However, when installing an EPS, the builders must choose the higher demand factor suggested according to the official approval demand factor of the building.