• Journal of environmental and Sanitary engineering
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• v.16 no.1
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• pp.47-52
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• 2001

In this study, we focused on typically problematic sulfide compounds Gas samples were captured at Unjung-ding landfill site in Metropolitan Kwangju with flux chamber and floating chamber, and analyzed for the amount of hydrogen sulfide($H_2S$), dimethyl sulfide $((CH_3)_2S)$ and dimethyl disulfide$((CH_3)_2S_2)$. From the gas pipe, landfill surface and leachate treatment plant, estimated total amount of $H_2S$ emission are 12.6ton/yr, 0.01ton/yr and 1.04ton/yr; estimated total amount of $((CH_3)_2S)$ 30.7ton/yr, 0.08ton/yr and 1.72ton/yr; and estimated total amount of ($((CH_3)_2S_2)$ 2.2tom/yr, 0.02ton/yr and 1.03ton/yr, respectively. Further in-depth study on co-relation between age, packing characteristics, temperature and humidity of landfill site and gas emission characteristics is needed.

• Proceedings of the KAIS Fall Conference
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• 2008.11a
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• pp.358-361
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• 2008

본 논문에서는 열화상촬영기 및 온도분포 해석 프로그램을 이용하여 금형가열온도와 실제 금형온도의 온도편차를 비교하여 금형가열 시 Stamper 표면의 온도분포를 해석하였다. 또한 전열가열방식(E-MOLD)을 이용하여 복합기능 도광판(Prismless LGP)을 제조하였고, 금형온도에 따른 복합기능 도광판(Prismless LGP)의 광특성 평가를 하였다. 그 결과 금형온도가 증가할수록 패턴 전사성 향상으로 인해 휘도 또한 증가하였고, 특히 유리전이온도($140^{\circ}C$) 이상에서 크게 상승하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.234-237
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• 2008

분류층 가스화기에서 가스화기 운전 온도는 슬래그의 원활한 배출과 가스화기 성능 등에 영향을 미친다. 가스화기 운전온도는 또한, 석탄 및 산소 소비량에도 영향을 미쳐 궁극적으로는 가스화 플랜트의 주요 설비 용량을 결정하는 주요 요인중의 하나이다. 가스화기 운전 온도가 일정수준 이상으로 증가할 경우 냉가스 효율이 저하되고 가스화 성능에 약 영향을 미친다. 본 논문에서는 Coal 및 Flux 공급장치, 슬래그 배출장치 당의 구성을 설명하고 Flux 투입량에 따른 슬래그 Tcv, 가스화기 성능 등을 예측하였다. 또한, 300MW IGCC 실증 가스화플랜트 엔지니어링을 위한 예비단계로 석회석 투입에 따른 Flux 공급장치를 포함한 Feeding 설비 용량, 슬래그처리설비 용량, 가스화기 내부 및 출구 적정온도를 예측하였다.

• International Journal of Automotive Technology
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• v.3 no.2
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• pp.57-62
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• 2002

It is well known that the entrained air in oil causes appreciable reduction in the stiffness of hydraulic systems. It makes the response delay of the systems and sometimes destroys the stability. Because the hydraulic systems of automatic transmissions are operated in relatively low pressure and high temperature, it is very important to analyze the effects of the air included in automatic transmission fluid. However, it is difficult to derive the generalized model to describe the effective bulk modulus theoretically or measure it in actual operating conditions of automatic transmissions. This paper reviews previous studies of the air effects in hydraulic systems and the measurement techniques of the effective bulk modulus in operating conditions. Based on this work, the theoretical model with moderate complexity and the measurement technique of the effective bulk modulus considering entrained air effect at real operating conditions are suggested. Our paper also shows that the quantity of the entrained air in the automatic transmission fluid can be estimated from the experimental results.

• Proceedings of the Korean Reliability Society Conference
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• 2004.07a
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• pp.129-137
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• 2004

This paper presents an accelerated life test for burnout of tungsten filament of incandescent lamp. From failure analyses of field samples, it is shown that their root causes are local heating or hot sports in the filament caused by tungsten evaporation and wire sag. Finite element analysis is performed to evaluate the effect of vibration and impact for burnout, but any points of stress concentration or structural weakness are not found in the sample. To estimate the burnout life of lamp, an accelerated life test is planned by using quality function deployment and fractional factorial design, where voltage, vibration, and temperature are selected as accelerating variables. We assumed that Weibull lifetime distribution and a generalized linear model of life-stress relationship hold through goodness of fit test and test for common shape parameter of the distribution. Using accelerated life testing software, we estimated the common shape parameter of Weibull distribution, life-stress relationship, and accelerating factor.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.130-131
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• 2018

The compressive strength of concrete is determined by various influencing factors. However, the conventional method for estimating the compressive strength of concrete has been suggested by considering only 1 to 3 specific influential factors as variables. In this study, nine influential factors (W/B ratio, Water, Cement, Aggregate(Coarse, Fine), Fly ash, Blast furnace slag, Curing temperature, and humidity) of papers opened for 10 years were collected at 4 conferences in order to know the various correlations among data and the tendency of data. The selected mixture and compressive strength data were learned using the Deep Learning Algorithm to derive an estimated function model. The purpose of this study is to investigate the effect of the number of hidden layers on the prediction performance in the process of estimating the compressive strength for an arbitrary combination.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.78.2-78.2
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• 2011

We utilize Sloan Digital Sky Survey DR7 spectroscopy of ~600 emission line galaxies (ELGs) in the Virgo and Ursa Major clusters to investigate their chemical properties depending on the environments. We derived chemical abundances of galaxies using either a direct estimation of the electron temperature or empirical calibrations. We also estimated star formation rates (SFRs) using H alpha and GALEX ultraviolet (UV) luminosities. We see no significant difference of UV colors and SFRs of ELGs between the Virgo and Ursa Major, indicating weak dependence of their star formation activity on global cluster environment. We also discuss the segregation of gas-phase element abundances in cluster environment.

• Nuclear Engineering and Technology
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• v.30 no.3
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• pp.222-234
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• 1998

The Westinghouse OT$\Delta$T DNB protection logic heavily restricts the operation region by applying the same logic for a full range of operating pressure in order to maintain its simplicity. In this work, a fuzzy neural network method is used to estimate the DNB protection limit using the measured average temperature and pressure of a reactor core. Fuzzy system parameters are optimized by a hybrid learning method. This algorithm uses a gradient descent algorithm to optimize the antecedent parameters and a least-squares algorithm to solve the consequent parameters. The proposed method is applied to Yonggwang 3&4 nuclear power plants and the proposed method has 5.99 percent larger thermal margin than the conventional OT$\Delta$T trip logic. This simple algorithm provides a good information for the nuclear power plant operation and diagnosis by estimating the DNB protection limit each time step.

• Nuclear Engineering and Technology
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• v.29 no.3
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• pp.251-259
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• 1997

This paper describes experimental investigations of helium-air exchange flows through partitioned opening and too-opening. Such exchange flows may occur following rupture accident of stand pipe in high temperature engineering test reactor. A test vessel with the too types of small opening on top of test cylinder is used for experiments. An estimation method of mass increment is developed to measure the exchange now rate. Upward flow of the helium and downward flow of the air in partitioned opening system interact out of entrance and exit of the opening. Therefore, an experiment with too-opening system is made to investigate effect of the fluids interaction of partitioned opening system. As a result of comparison of the exchange flow rates between too types of the opening system, it is demonstrated that the exchange flow rate of the two-opening system is larger than that of the partitioned opening system because of absence of the effect of fluids interaction.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.643-649
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• 2008

The purpose of this study is to establish a standard for unit cooling load in central control type apartment applied district cooling. The model of unit household was selected. And the standard of coefficient of overall heat transmission, location of unit household, indoor air temperature, solar radiation & thermal conduction at window and interior load was selected, and region, expansion or non-expansion of balcony, pyeong type, azimuth, rate of window area was applied as parameter. And then cooling load simulation was performed. Based on the result of simulation, the synthetic district cooling load was presented for selecting heat source of apartment applied district cooling, and unit cooling load was analyzed according to design parameter.