• 화약ㆍ발파
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• 제27권2호
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• pp.56-60
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• 2009

물리학적 측면에서 에너지의 개념은 일하는 능력으로 정의된다. 기존의 석탄 석유등 화석연료를 대체하기 위해 1980년 이후부터 천연가스 원자력 등의 사용이 증가하였으나 환경오염문제로 태양열 풍력 조력 지열 등 대체에너지로의 전환을 촉진하고 있다. 그러나 에너지 이용효율 측면에서는 원자력 에너지와 화약 가스 등 화학에너지와는 비교가 되지 않는다. 본 논문에서는 환경(대체)에너지의 한계점을 뛰어 넘을 수 있는 방안을 연구하기 위하여 그린에너지의 현황을 조사하였으며, 고효율 에너지원에 대한 청정화와 응용 및 개발방향에 대해 검토, 연구 하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집
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• pp.175-179
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• 2005

The main objective of this paper is to module design and pressure relief test a new type of polymer gapless surge arrester for power distribution line. Metal oxide surge arrester for most electric power system applications, power distribution line and electric train are now being used extensively to protect overvoltage due to lightning. Surge arresters with porcelain housing must not have explosive breakage of the housing to minimize damage to other equipment when subjected to internal high short circuit current. When breakdown of gapless elements in a surge arrester occurs due to flashover, fault short current flows through the arrester and internal pressure of the arrester rises. The pressure rise can usually be limited by fitting a pressure relief diaphragm and transferring the arc from the inside to the outside of the housing. However, there is possibility of porcelain fragmentation caused by the thermal shock, pressure rise, etc. Non-fragmenting of the housing is the most desired way to prevent damage to other equipment. The pressure change which is occurred by flashover become discharge energy. This discharge energy raises to damage arrester housing and arrester housing is dispersed as small fragment. Therefore, the pressure relief design is requested to obstruct housing dispersion.

• 한국인터넷방송통신학회논문지
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• 제14권5호
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• pp.111-115
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• 2014

전력선 통신은 전기를 사용할 수 있는 어느 곳에서든지 데이터 전송 네트워크를 구축하기 위해 사용할 수 있다. 이러한 종류의 통신 시스템은 스마트 그리드와 홈 네트워크를 포함한 다양한 적용 분야에서 네트워크 구축을 위한 기반으로 제공된다. 반면에 전력선 통신은 다양한 종류의 간섭과 잡음에 취약하다. 또한 네트워크에 연결된 전기적 부하의 양과 종류에 따라 전력선 통신 채널의 특성이 지속적으로 변화한다. 특히 일상생활에서 스마트 기기의 폭발적인 증가에 의한 직류전원 공급장치의 사용이 증가함에 따라 전력선 통신 채널의 간섭 영향이 증가한다. 본 논문에서는 실험을 통하여 직류전원 공급장치의 동작에 따른 전력선 통신 채널의 영향과 데이터 전송 성능을 분석한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 유기절연재료 방전 플라즈마연구회
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• pp.108-111
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• 2003

The main objective of this paper is to module design and pressure relief test a new type of polymer gapless surge arrester for power distribution line. Metal oxide surge arrester for most electric power system applications, power distribution line and electric train are now being used extensively to protect overvoltage due to lightning. Surge arresters with porcelain housing must not have explosive breakage of the housing to minimize damage to other equipment when subjected to internal high short circuit current. When breakdown of gapless elements in a surge arrester occurs due to flashover, fault short current flows through the arrester and internal pressure of the arrester rises. The pressure rise can usually be limited by fitting a pressure relief diaphragm and transferring the arc from the inside to the outside of the housing. However, there is possibility of porcelain fragmentation caused by the thermal shock, pressure rise, etc. Non-fragmenting of the housing is the most desired way to prevent damage to other equipment. The pressure change which is occurred by flashover become discharge energy. This discharge energy raises to damage arrester housing and arrester housing is dispersed as small fragment. Therefore, the pressure relief design is requested to obstruct housing dispersion.

• 한국안전학회지
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• 제27권4호
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• pp.26-32
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• 2012

With a progress of electrical and electronic technology, radio-frequency including high frequency components are widely to various industrial installations. Some of them are used in hazardous locations where explosive or flammable gases exist. As a result, ignition of such gases may be induced by a spark discharge when the radio frequency circuits are switched on or off. The purpose of this study is to investigate the ignition hazards of some kind of flammable mixtures based on the IEC 60079-11 publication. In this experiment, we used a high frequency resistive circuit which consists of a co-axial cable, a 20 ${\Omega}$, 30 ${\Omega}$, 40 ${\Omega}$ and 50 ${\Omega}$ resistor and two kind of power amplifier with frequency range up to almost 1 MHz and 50 MHz. Experimental results show that the ignition of the acetyleneair, ethylene-air mixtures and methane-air mixtures due to spark discharge depends primarily on the frequency of the power source in the resistive circuit the minimum ignition voltage increases gradually with the increase of the frequency.

• Tribology and Lubricants
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• 제24권1호
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• pp.21-26
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• 2008

A pin bush bearing is one of the most important element in the piston engine which is joined a piston to a connecting rod. A pin bush is suffered by heat and changeable repeat loads, which are come from the explosive gas heat and pressures during a reciprocating stroke. Therefore, a tribological behavior of pin bush bearings is very severe compared to other parts of a piston assembly. To keep a stable operation of pin bush bearings effectively, it would be satisfied with proper oil film strength for severe operating conditions and durability, which are strongly related to the oil film thickness, oil film pressure, and a friction loss power. The computed results show that the viscosity of engine oils slightly affects to the minimum oil film thickness and oil film pressure distribution, but is an influential parameter on a total friction loss power. Thus the low viscosity engine oils for an increased operation condition should select a high level of base oil and add a viscosity index improver as an oil film additive.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 1995년도 제4회 학술강연회논문집
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• pp.171-175
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• 1995

Semiconductor diode lasers that can generate one watt or more of optical energy for tens of milliseconds (quasi continuous wave) are now readily available. Several researchers have demonstrated that this power level, when properly coupled, can reliably initiate pyrotechnic mixtures. This means that the initiator containing the pyrotechnic can be protected against inadvertent initiation from electromagnetic radiation or electrostatic discharge by a conducting Faraday cage surrounding the explosive. Only a small dielectric window penetrates the housing of the initiator, thereby eliminating the conductors necessitated by a bridgewire electroexplosive device. The diode laser itself, however, functions at a low voltage (typically 3 volts) and hence is susceptible to inadvertent function from power supply short circuits, electrostatic discharge or induced RF energy. The rocket motor arm-fire device de-scribed in this paper uses a diode laser, but protects it from unintentional function with a Radio Frequency Attenuating Coupler (RFAC).The RFAC, invented by ML Aviation, a UK company, transfers power into a Faraday cage via magnetic flux, thereby protecting the diode, its drive circuit and the pyrotechnic from all electromagnetic and electrostatic hazards. The first production application of a diode laser and RFAC device was by the Korean Agency for Defense Development.

• 방사성폐기물학회지
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• 제20권1호
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• pp.99-110
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• 2022

In decommissioning a nuclear power plant, numerous concrete structures need to be demolished and decontaminated. Although concrete decontamination technologies have been developed globally, concrete cutting remains problematic due to the secondary waste production and dispersion risk from concrete scabbling. To minimize workers' radiation exposure and secondary waste in dismantling and decontaminating concrete structures, the following conceptual designs were developed. A micro-blast type scabbling technology using explosive materials and a multi-dimensional contamination measurement and artificial intelligence (AI) mapping technology capable of identifying the contamination status of concrete surfaces. Trials revealed that this technology has several merits, including nuclide identification of more than 5 nuclides, radioactivity measurement capability of 0.1-10⁷ Bq·g^-1, 1.5 kg robot weight for easy handling, 10 cm robot self-running capability, 100% detonator performance, decontamination factor (DF) of 100 and 8,000 cm²·hr^-1 decontamination speed, better than that of TWI (7,500 cm²·hr^-1). Hence, the micro-blast type scabbling technology is a suitable method for concrete decontamination. As the Korean explosives industry is well developed and robot and mapping systems are supported by government research and development, this scabbling technology can efficiently aid the Korean decommissioning industry.

• 한국화재소방학회논문지
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• 제14권2호
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• pp.33-38
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• 2000

전자산업의 공정에서 PCB기판납땜은 괼수적이며 이에 사용하는 Flux내 용제인 IPA(Iso--propyl alcohol)와 메탄올은 인화성과 폭발성이 강한 물질로 화재위험성이 대단히 높다. 또한 메탄올은 유독성물질로 지정되어 있으며, 환경법상 VOC(Volatile Organic Compound : 휘발성유기화합물)규제물질로 지정되어 있어 대체물질 개발이 절실히 요구된다. 이에 기존 Flux특성을 가지고 있으면서 화재위험성은 없고, 휘발성유기화합물 규제물질에는 해당되지 않는 디클로로프로판(Dichloropropane, DCP)를 주성분으로 하여 Flux 특성에 맞는 안정제 및 첨가제를 적정 조성비로 조합하여 용제를 개발하였다. 그 결과 200ppm의 작업환경허용농도를 470 ppm으로 완화시킬 수 있었으며 납땜불량율은 0.083%에서 0%로, 퍼짐성은 85%에서 87%로, 전연저항은 1.0$\times$$10^{12}$$\Omega$에서 6.9$\times$$10^{12}$/$\Omega$으로 기존 Flux보다 우수하였다. 그러므로 Flux의 안정성은 물론 환경안전측면과 품질, 생산성도 향상이 가능함을 확인하였고, 품질 특성시험 및 제품 신뢰성 시험 결과 만족할 만한 곁과를 얻었다.

• 설비공학논문집
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• 제16권11호
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• pp.1051-1059
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• 2004

Two phase thermosyphone loop for electronics cooling are designed and manufactured to test its performance under the partial load and low environment temperature conditions. The thermosyphone device has six evaporators connected parallel for the purpose of cooling six power amplifier units (PAU) independently. The heater modules for simulating PAUs are adhered with thermal pad to the evaporator plates to reduce the contact resistance. There are unbalanced distributions of liquid refrigerant in the differently heated evaporators due to the vapor pressure difference. To reduce the vapor pressure differences caused by partial heating, two evaporators are connected each other using the copper tube. The pressure regulation tube successfully reduces these unbalances and it is good candidates for a field distributed systems. Under the low environment temperature operating condition, such as $-30^{\circ}C$, there may be unexpected subcooling in condenser. It leads the very low saturation pressure, and under this condition there exists explosive boiling in evaporator. The abrupt pressure rise due to the explosive boiling inhibits the supplement of liquid refrigerant to the evaporator for continuous cooling. Finally the cooling cycle will be broken. For the normal circulation of refrigerant there may be an optimum cooling air flow rate in condenser to adjust the given heat load.