• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.485-490
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• 2005

With the historical opening of the express rail, Korea has joined the league of France, Japan, Germany and Spain and entered into the super high-speed train era. Opening of the express rail will not only bring about enormous changes to the lives of Koreans, but it will also have a huge influence on the economic, social and cultural aspects of the country. With construction of the Seoul - Busan KTX line, railway passenger transportation capacity and freight transportation capacity will increase. Fast, safe, convenient and environmentally friendly, the express rail is a product of the latest technology and will secure its position as the newest and most preferred method of transportation for the next generation. As the traffic noise, train noise from KTX will become a social problems with the acceleration of speed and increase in the lines. In order to predict the train noise propagation from KTX, this paper presents the sound source system, the calculation model and the scale model experiment. Noise level unit patterns of a KTX that take the rolling noise, the motor noise and aerodynamic noise into consideration are simulated by the scale model experiment and numerical analysis.

• 에너지공학
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• 제12권2호
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• pp.124-130
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• 2003

본 연구에서는 정적연소실을 이용하여 차량용 대체연료로써 메탄 및 수소첨가 메탄의 연소특성을 수소첨가율, 점화위치 및 점화방법에 따라 고찰하였다. 그 결과 연소효율, 최고연소압력 등과 같은 연소특성을 악화시키지 않고 희박 혼합기 조건하에서도 MSCDI 장치 사용에 의해 전 연소시간과 NO 농도를 저감시킬 수 있었다. 또한, 수소를 천연가스의 주 성분인 메탄에 혼합함에 따라 전 연소시간은 순수 메탄만을 사용할 때에 비해 단축되었으며, 이와 동시에 연소촉진율도 순수 메탄만을 사용하였을 때에 비해 상당히 향상되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1774-1777
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• 1996

In this paper, applicability of SI-PD(switching impulse - partial discharge) testing method was put on an attempt as a newly proposed diagnostic method for the underground distribution power cable system in Korea. For this purpose, SI-PD testing equipment was designed, and tests were performed using artificial needle-type defects integrated into the 22.9 kV CN/CV cables in drder to prove its reliability. As a result, arc noises, generated from spark gap, were considerably decreased by use of a pneumatic switch immersed into oil, and artificial needle-type defects were well detected with impulse voltage level under $2U_0$. These results imply that it is likely possible to apply SI-PD measurement method as a the nondistructive test for the 22.9 kV CN/CV cable system in Korea.

• 대한기계학회논문집B
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• 제24권6호
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• pp.753-759
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• 2000

Photoelectric charging is a very efficient way of charging small particles. This method can be applied to combustion measurement, electrostatic precipitator, metal separation and control of micro-contamination. To understand the photoelectric charging mechanism, particle charging of silver by exposure to ultraviolet is investigated in this study. Average charges and charge distributions are measured at various conditions, using two differential mobility analyzers, a condensation nucleus counter, and an aerosol electrometer. The silver particles are generated in a spark discharge aerosol generator. After that process, the generated particles are charged in the photoelectric charger using low-pressure mercury lamp that emits ultraviolet having wavelength 253.7 nm. The results show that ultra-fine particles are highly charged by the photoelectric charging. The average charges linearly increase with increasing particle size and the charge distribution change with particle size. These results are discussed by comparison with previous experiments and proposed equations. It is assumed that the coefficient of electron emission probability is affected by initial charge. The results also show that the charge distribution of a particle is dependent on initial charge. Single changed particle, uncharged particle and neutralized particle are compared. The differences of charge distribution in each case increase with increasing particle size.

• 대한기계학회논문집B
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• 제24권6호
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• pp.760-768
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• 2000

Filter efficiency of electrically charged particle in uncharged fibrous filter was measured. In previous studies, the effect of charged particle on filter efficiency was investigated but there was difficulty in measuring of image effect that is appeared at the charged small particle. We could easily measure the image effect with charging small particles by photoelectric charging. The spark discharge aerosol generator and a differential mobility analyzer (DMA) were used to generate sub-micron monodisperse particles (${\leq}200$ nm). The generated particles were charged in photoelectric charging process using ultraviolet lamp and electric field. The filter efficiency of the charged particles, classified by another DMA, was measured in filter tester using a condensation nucleus counter (CNC) as function of particle diameter, particle charge and airflow velocity. It is shown that the filter efficiency increases with increasing charge number of the particle and is affected by particle size and flow velocity. Single fiber filter efficiency mainly depends on image force parameter and peclet number. The peclet number was not considered at previous other papers. We propose a modi fied experimental correlation as function of image force parameter and peclet number.

• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.280-285
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• 2014

In order to evaluate the insulation deterioration in the stator windings of five gas turbine generators(137 MVA, 13.8 kV) which has been operated for more than 13 years, diagnostic test and AC dielectric breakdown test were performed at phases A, B and C. These tests included measurements of AC current, dissipation factor, partial discharge (PD) magnitude and capacitance. ${\Delta}I$ and ${\Delta}tan{\delta}$ in all three phases (A, B and C) of No. 1 generator stator windings showed that they were in good condition but PD magnitude indicated marginally serviceable and bad level to the insulation condition. Overall analysis of the results suggested that the generator stator windings were indicated serious insulation deterioration and patterns of the PD in all three phases were analyzed to be internal, slot and spark discharges. After the diagnostic test, an AC overvoltage test was performed by gradually increasing the voltage applied to the generator stator windings until electrical insulation failure occurred, in order to determine the breakdown voltage. The breakdown voltage at phases A, B and C of No. 1 generator stator windings failed at 28.0 kV, 17.9 kV, and 21.3 kV, respectively. The breakdown voltage was lower than that expected for good-quality windings (28.6 kV) in a 13.8kV class generator. In the AC dielectric breakdown and diagnostic tests, there was a strong correlation between the breakdown voltage and the voltage at which charging current increases abruptly ($P_{i1}$, $P_{i2}$).

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권4호
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• pp.253-260
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• 1999

In this paper, the impedance characteristic of wire-plate pulsed plasma reactor was investigated by experiment. The experiment have carried out under the several conditions of voltage, wire length and wire-plate distance. The impedance of reactor wad decreased with increasing voltage and wire length. The nature of discharge in reactor was changed from streamer corona to spark with increasing incident energy, from which we understood the critical energy density between the two discharges. Fromthis experiment, we proposed the method for the impedance matching between pulse generator and pulsed plasma reactor. Additionally, we succeeded in the analysis ofstray inductance of 0.5MW reactor using EMTP (ElectroMagnetic Transients Program). This means that EMTP is also useful for the analysis of inevitable stray inductance of forthcoming a large scale reactor.

• 한국자동차공학회논문집
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• 제16권6호
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• pp.176-183
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• 2008

Performance of electrostatic diesel PM filtration systems (E-DPS) with different types has been tested using the carbon particles generated by spark discharge in laboratory. Among the five electrostatic precipitators, the multiple wires cylindrical E-DPS with the highest collection efficiency and relatively lower differential pressure at the flow rate of $1\;m^3$/min, as an applicable device to diesel engine as an after treatment system, has been combined with another collection cylinder to improve the collection efficiency of diesel particulate matters generated from diesel engines. The multiple wires cylindrical E-DPS combined with the cylindrical collector showed the collection efficiency of more than 60% at the engine speed of 2,000 rpm with the engine loads of 25 and 50%.

• 한국재료학회지
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• 제12권5호
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• pp.353-358
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• 2002

The microstructure and growth behaviors of anodic oxide layers on titanium were investigated. $TiO_2$ oxide films were prepared by anodizing at constant voltages of 180 and 200V in sulfuric acid electrolyte. The anodic $TiO_2$ layer formed at 200V showed a cell structure with more irregular pore shapes around the interface between the anodic oxide layer and the substrate titanium compared with that formed at 180V. Irregular shape of pores at the initial stage of anodization seemed to be attributed to spark discharge phenomena which heavily occurred during increasing voltages. The thickness of the anodic oxide film increased linearly at a rate of $1.9{\times}10^{ -1}\mu\textrm{m}$/min. The oxide layers formed at 180 and 200V were composed mainly of anatase structure, and the anodizing process could be suggested as one of fabrication methods of photocatalytic $TiO_2$.

• 조명전기설비학회논문지
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• 제23권6호
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• pp.72-77
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• 2009

2006년 우리나라에서 발생된 전기화재 중 63.2[%]는 전기배선에서 단락에 의해 발생되었다. 따라서 전기배선에 의한 화재가능성에 대한 연구가 필요하다. 이에 본 연구에서는 통전중인 도선이 주변 조영재와 접촉할 가능성 및 접촉에 의한 화재가능성에 대하여 연구하였다. 그 결과 도선에 흐르는 전류가 클수록 주변의 조영재와 접촉할 가능성이 높고 특히, 도선의 온도가 도선피복의 발화점을 넘는 경우 도선과 주변 조영재 간에 불꽃을 동반하는 방전이 발생됨으로써, 전기화재 가능성이 더욱 커지는 것을 실험적으로 알 수 있었다.