• Journal of the Korean Electrochemical Society
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• v.8 no.1
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• pp.6-11
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• 2005

Direct borohydrides fuel cell (DBFC) was emerged to complement the problem of DMFC's low performance and methanol crossover to the cathode and to apply the fuel cell to portable and mobile devices. In this study, the characteristics of novel catalysts was tested to establish the electrode preparation process of DBFC. Pt black and carbon supported-Pt by paste method were used as the cathode catalysts. Pt black, carbon supported-Au and $AB_5$ alloy were used as the anode catalysts. The characteristics of the electrodes were analyzed by XRD, SEM, EDS. The performance test of single cell using the electrodes were carried out in order to evaluate the electrode performance. In the result, the maximum power output was obtained as 366 mW/mg when using Pt/C as anode and cathode catalysts.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2001.06a
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• pp.11-13
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• 2001

본 연구진은 비교적 청정한 공기질을 유지하는 것으로 알려진 강화도 하리지역을 중심으로 2001년 3월 봄철의 일주일 (3/20∼3/27) 기간동안 미량기체의 교환량을 측정하기 위한 공동연구사업을 수행하였다. 본 연구에서는 수은, VOC, 메탄, 비메탄계 탄화수소를 위시한 가스상 성분은 물론 입자상성분을 대표할 수 있는 PM 10의 농도를 지면상부 1m와 5m 고도에서 관측하였다.(중략)

• Journal of the Korean Institute of Gas
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• v.9 no.2 s.27
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• pp.1-7
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• 2005

The thermochemical parameters for safe handling, storage, transport, operation and process design of flammable substances are explosive limit, flash point, autoignition temperature, minimum oxygen concentration, heat of combustion etc.. Explosive limit and autoignition temperature are the major physical properties used to determine the fire and explosion hazards of the flammable substances. Explosive limit and autoignition temperature of methane fur LNG process safety were investigated. By using the literatures data, the lower and upper explosive limits of methane recommended 4.8 vol$\%$ and 16 vol$\%$, respectively. Also autoignition temperatures of methane with ignition sources recommended $540^{\circ}C$ at the electrically heated cruicible furnace (the whole surface heating) and recommended about $1000^{\circ}C$ in the local hot surface. The new equations for predicting the temperature dependence and the pressure dependence of the lower explosive limits for methane are proposed. The values calculated by the proposed equations were a good agreement with the literature data.

• Journal of the Korea Convergence Society
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• v.10 no.10
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• pp.7-13
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• 2019

The natural gas (NG), mostly methane leaks into the air, it is a big problem for the climate. detected NG leaks under U.S. city streets and collected data. In this paper, we introduced a Deep Neural Network (DNN) classification of prediction for a level of NS leak. The proposed method is OrdinalEncoder(OE) based K-means clustering and Multilayer Perceptron(MLP) for predicting NG leak. The 15 features are the input neurons and the using backpropagation. In this paper, we propose the OE method for labeling target data using k-means clustering and compared normalization methods performance for NG leak prediction. There five normalization methods used. We have shown that our proposed OE based MLP method is accuracy 97.7%, F1-score 96.4%, which is relatively higher than the other methods. The system has implemented SPSS and Python, including its performance, is tested on real open data.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.2
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• pp.183-190
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• 1995

Various factors such as sampling height in the chamber, sampling interval, sampling time at daytime and the effects of pedoturbation on methane emission during chamber installation were evaluated using a simplified closed static chamber method to measure methane flux in paddy soils. Sampling height of the chamber for representative samples was 65cm. An additional DC fan was required to attain an even methane gradient in the chamber. Considering the change of methane concentration and air temperature in the chamber, sampling is recommended to finish within 30 minutes after starting sampling. The aim of setting DC fan in the chamber was to get the thermal equilibrium in the chamber as well as the representative samples. Suitable time to collect the gas samples representing the day's methane flux was 0900~1200 hours. Gas sampling was possible even after installation of small chambers if the elapsed time was more than 6 hours and supporting stand would be to be added to minimize pedoturbation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.285-291
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• 2012

A lot of research on the stability of nonpremixed flames has focused on the fuel-nozzle and quarl geometries. Of the work carried out, only a small amount has focused on the stability of the nonpremixed flame according to the recession distance and air-nozzle geometry. Therefore, in this study, a coaxial-diffusion-type gas burner with a swirler is designed for the systematic investigation of the combustion characteristics of a $CH_4$ flame depending on the recession distance and secondary air-nozzle geometry. 1st air is flowed through the swirler, and 2nd air is flowed through each nozzle. It is shown that the secondary air velocity greatly influences the flame length and shape. There is an optimum recession distance for each nozzle for the best combustion efficiency. In this study, it is shown that the optimized recession distance is nearly half the outer diameter of the air-supply nozzle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1999.04a
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• pp.25-25
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• 1999

안정화 화염으로 수소 확산 화염을 이용한 메탄/공기 난류 예혼합 화염의 미연가스 영역의 난류 특성을 측정하였다. 측정은 동일한 위치에 대해서 화염이 존재할 때와 존재하지 않을 때에 대해 수행되었다. 버너 출구 레이놀즈 수 7000에서 당량비 0.6과 1.0의 경우에 대해 실험이 수행되었다. 난류 유동장은 2색 레이저 유속계에 의해 측정되었다. 21개의 위치에 대해서 반복적으로 측정이 수행되었다.

• Journal of the Korean Society of Combustion
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• v.10 no.2
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• pp.35-41
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• 2005

Behaviors of lean premixed flame of propane/air and methane/air flame anchored by a pilot flame in a tube were investigated experimentally varying the mean velocity from 10 to 140 cm/s and the equivalence ratio from 0.45 to 0.8. Behaviors of both flames are divided into five regions of stable, flash-back, tail-out, flickering and vibrating. General characteristics of each region and Le number effect are investigated. Two main instabilities, flickering and vibration, are both unstable but the instability mechanism, the frequency and the amplitude of pressure fluctuation are different. In the edge of the vibrating region, pressure fluctuation repeats generation and extinction. Repeated growth and decrease of the amplitude of pressure fluctuation are explained by Rayleigh#s index.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2012.04a
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• pp.58-61
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• 2012

엔진나셀 화재를 둔각물체에서 분사된 연료제트 화염으로 모사하여 화염안정화 및 소화특성을 조사하기 위해 실험과 수치해석을 수행하였다. 연료제트는 공기유동에 동측류인 경우와 대향류인 경우에 사각의 둔각물체에서 분사하였고, 소화약제는 이산화탄소와 질소를 사용하여 공기유동에 희석시켜주었으며 연료로는 메탄을 사용하였다. 본 실험의 결과를 해석하고 보충하기 위하여 LES(Large Eddy Simulation)을 기반으로 하는 FDS(Fire Dynamics Simulator)를 이용하여 비반응 유동장에서의 혼합특성과 둔각물체 후류의 유동특성을 살펴보았다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.167-175
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• 2018

Natural gas is a clean fuel that discharges almost no air-contaminating substances. This study examined the simultaneous reduction of $CH_4$ and NOx of NGOC/LNT catalysts for CNG buses related to the improvement of the $de-CH_4/NOx$ performance, focusing mainly on identifying the additive catalysts, loading of the washcoat, stirring time, and types of substrates. The 3wt. % Ni-loaded NGOC generally exhibited superior $CH_4$ reduction performance through $CH_4$ conversion, because Ni is an alkaline, toxic oxide, and exerts a reducing effect on $CH_4$. A excessively small loading resulted in insufficient adsorption capacity of harmful gases, whereasa too high loading of washcoat caused clogging of the substrate cells. In addition, with the economic feasibility of catalysts considered, the appropriate amount of catalyst washcoat loading was estimated to be 124g/L. The NOx conversion rate of the NGOC/LNT catalysts stirred from $200^{\circ}C$ to $550^{\circ}C$ for 5 hours showed 10-15% better performance than the NGOC/LNT catalysts mixed for 2 hours over the entire temperature range. The NGOC/LNT catalysts exhibitedapproximately 20% higher $de-CH_4$ performance on the ceramic substrates than on the metal substrates.