• E2M - 전기 전자와 첨단 소재
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• 제8권3호
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• pp.278-284
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• 1995

Thin fihn SnO$_{2}$ Gas Sensor was fabricated by electron-beam evaporation system and the target made by general firing method for the purpose of detecting gas components in air, especially methane gas. SnO$_{2}$ thin film was prepared on the polished alumina substrate which Pt interdigital electrode was precoated. The effects of annealing temperature and substrate temperature on the structural properties of SnO$_{2}$ thin film on glass were investigated using the X-ray diffraction. The good crystalline structure is formed when substrate temperature is 150[.deg. C] and annealing condition is 550[.deg. C], 1[hour]. And the sensing properties at various thickness of the SnO$_{2}$ thin film and the effects of PdCI$_{2}$ addition were also investigated. The good result is showed when the thickness is below 1000[.angs.] and the quantity of PdCI$_{2}$ addition is 4[wt%]. The thickness of SnO$_{2}$ thin film was measured by .alpha.-step and Elliopsometer.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권4호
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• pp.197-203
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• 2001

Recently, the construction of gas insulated substation(GIS)s has been increased in Korea. But, the whole quantity of the VTs which were used in GIS has been imported. Under the circumstance that $SF_6$ gas power apparatus are being developed up to 800kV rating in Korea, the development of EＨＶ　$SF_6$ gas VT is essential for localizing the power apparatus. As for EHV VT, destructive ferroresonance can be generated due to the combination of capacitiances between poles of circuit breaker, ground capacitance of bus and nonlinear excitation property of VT core. But the theoretical analysis about ferroresonance has not been fully achieved in Korea. Therefore, in this paper the authors would like to contribute for localizing EHV $SF_6$ gas VT by developing the diagram of ferroresonance zone according to the parameters of the circuit and the saturable reactor.

• 한국자동차공학회논문집
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• 제23권4호
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• pp.444-453
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• 2015

In the previous study, several problems were observed in a NG conversion vehicle, which were fail of air-fuel ratio closed loop control, aggravated fuel economy, increased harmful emission and declined roadability. It was provisionally supposed that the mismatch of injection system with the engine caused these performance deterioration. In this context, the characteristics of fuel injection system of commercial conversion kit for NG were investigated experimentally varying the engine speed, fuel rail pressure and volume. The results are as follows; The injection quantity decreases as the engine speed increases due to the extremely small rail volume of the presenting system and flow rate of No. 2 injector are always lower than that of the other ones regardless of the speed under the dynamic operation condition. Furthermore the existing system does not meet the required fuel quantity for the normal engine operation over 3000 RPM. On the other hands, the large rail volume systems ease and/or eliminate the difference of injection quantity between the injectors according to the speed variation, however, these systems decrease injection flow rate and still cannot supply sufficient fuel. Finally, suitable combination of the higher rail pressure and the larger rail volume might be a solution about these problems.

• Environmental Analysis Health and Toxicology
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• 제27권
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• pp.12.1-12.8
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• 2012

Objectives: The aim of this study was to identify the health and environmental risk factors of air contaminants that influence environmental and respiratory diseases in Gyeongju, Pohang and Ulsan in South Korea, with a focus on volatile organic compounds (VOCs). Methods: Samples were collected by instantaneous negative pressure by opening the injection valve in the canister at a fixed height of 1 to 1.5 m. The sample that was condensed in $-150^{\circ}C$ was heated to $180^{\circ}C$ in sample pre-concentration trap using a 6-port switching valve and it was injected to a gas chromatography column. The injection quantity of samples was precisely controlled using an electronic flow controller equipped in the gas chromatography-mass spectrometer. Results: The quantity of the VOC emissions in the industrial area was 1.5 to 2 times higher than that in the non-industrial area. With regards to the aromatic hydrocarbons, toluene was detected at the highest level of 22.01 ppb in Ulsan, and chloroform was the halogenated hydrocarbons with the highest level of 10.19 ppb in Pohang. The emission of toluene was shown to be very important, as it accounted for more than 30% of the total aromatic hydrocarbon concentration. Conclusions: It was considered that benzene in terms of the cancer-causing grade standard, toluene in terms of the emission quantity, and chloroform and styrene in terms of their grades and emission quantities should be selected for priority measurement substances.

• 전기학회논문지
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• 제58권8호
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• pp.1496-1503
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• 2009

The United Nations Framework Convention on Climate Change (UNFCCC) is an international environmental treaty to stabilize greenhouse gas concentrations in the atmosphere. In order to fulfil the commitments of the countries in an economically efficient way, the UNFCCC adapted the emission trading scheme in the Kyoto Protocol. If the UNFCCC's scheme is enforced in the country, considerable changes in electric power industry are expected due to the imposed greenhouse gas emission reduction. This paper proposes a game theoretic model of the case when generation companies participate in both competitive electricity market and emission market simultaneously. The model is designed such that generation companies select strategically between power quantity and greenhouse gas reduction to maximize their profits in both markets. Demand function and Environmental Welfare of emission trading market is proposed in this model. From the simulation results using the proposed model the impact of the emission trading on generation companies seems very severe in case that the emission prices are significantly high.

• 한국분무공학회지
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• 제18권4호
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• pp.196-201
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• 2013

SCR(Selective Catalytic Reduction) is a major after-treatment solution to reduce NOx emission in recent diesel engines. In this study, a metal foam is applied as an alternative SCR substrate and tested in a commercial diesel engine to compared with a conventional ceramic SCR system. Basic engine test from ND-13 mode shows that a metal foam catalyst has lower NOx conversion efficiency than a ceramic catalyst especially over $350^{\circ}C$. A metal foam catalyst has characteristics of high exhaust gas pressure before a SCR catalyst and high heat transfer rate due to its material and structure. NOx conversion efficiency of a metal foam catalyst shows an increasing tendency along with the increase of exhaust gas temperature by $500^{\circ}C$. The effect of urea injection quantity variation is also remarkable only at high exhaust gas temperature.

• 한국대기환경학회지
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• 제20권3호
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• pp.303-315
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• 2004

The change of land use such as the construction of way in mountainous area and tunnel leads to the quantitative change of the greenhouse gas. This study tried to clarify the effect of the change of land use around Miryang Ice Valley on thermal environment of micro-meteorological scale by numerical experiment. We carried out several numerical experiment under different atmospheric conditions with different amount of greenhouse gases. Heating rate increased by the greenhouse gas in the ground level is average of 0.0073 K/day. And the increasing rate if smaller than the daily average heat crossing quantity.

• 한국정밀공학회지
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• 제6권1호
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• pp.75-84
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• 1989

This paper deals with the effect of $N_2$ and $H_2$gas mixture ratio and ion-nitriding time in the corrosion fatigue fracture behavior of ion-nitrided SCM4 steel with notch subject to rotary bending stress. The specimens were treated rapid water cooling after ion-nitriding at $500^{\circ}C$ Torr for 1 hour and 3 hours in gas mixtures of 80% $N_2$and 50% $N_2$. The fatigue limit and the fracture strength of corrosion fatigue depended on $N_2$gas quantity and ion-nitriding time. The ion-nitrided specimens showed about 88 .approx. 158% increase in the fracture strength of corrosion fatigue in $10^6$ cycles than non-nitrided specimens. The corrosion failure is due to corrosion pitting of the surface, and the propargation of cracks started at the surface into the core.

• 한국응용과학기술학회지
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• 제33권1호
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• pp.213-223
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• 2016

The validity of landfill gas models is an important problem considering that they are frequently used for landfill-site-related policy making and energy recovery planning. In this study, the Monte Carlo method was applied to an landfill gas generation model in order to enhance conformity. Results show that the relative mean deviation between measured data and modeled results (MD) decreased from 19.8% to 11.7% after applying the uncertainty range of Intergovernmental Panel on Climate Change (IPCC) to the methane-generation potential and reaction constants. Additionally, when let reaction constant adjust derived errors from all other modeling components, such as model logic, gauging waste, and measured methane data, MD decreased to 6.6% and the disparity in total methane generation quantity to 2.1%.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.748-751
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• 2009

This paper provides a novel scheme to enhance luminous efficiency within Plasma Display Panels (PDPs). The He-Xe or Ne-Xe mixtures are mainly used in conventional PDP cells, where their discharge characteristics exemplify different behavior. Significantly, the excitation efficiency in He-Xe is lower than that of the Ne-Xe mixture. This paper demonstrates that by adding a small quantity of Ar or Kr gas in Ne-Xe mixture increases cell efficiency, while for the He-Xe mixtures their cell efficiency is reduced.