• 한국가스학회지
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• 제3권3호
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• pp.45-50
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• 1999

도심지내에 위치한 부천 LPG충전소 사고 조사를 통하여 가장 피해효과가 큰 탱크로리 폭발에 따른 결과를 분석하였다. 분석범위는 BLEVE 현상에 의한 방출열과 과압이 충전소주변에 위치한 구조물이나 인체에 미치는 영향을 대상으로, 실제 현장조사를 통하여 수집된 피해결과와 이론적인 모델(PHAST-Process Hazad Analysis Sortware Tools) 분석 결과를 비교하였다. 부천 LPG 충전소 폭발 사고의 피해효과는 방출열의 경우 두 가지 모두 큰 차이를 보이지 않았으나, 과압의 경우, 실제 피해는 이론적 모델분석결과의 약 $15\%$정도에 해당하는 축소된 거리에서 나타났다. 또한, 충전소 인근에 위치한 구조물에 대한 피해효과는 부분적으로 과압에 의한 균열 및 붕괴 현상보다는 열 효과에 의한 콘크리트 강도 저하와 성상변화가 크게 나타났다.

• Journal of Mechanical Science and Technology
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• 제15권1호
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• pp.88-97
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• 2001

The present study numerically investigates the fuel-air mixing characteristics, flame structure, and pollutant emission inside a double-swirler combustor. A PSR(Perfectly Stirred Reactor) based microstructural model is employed to account for the effects of finite rate chemistry on the flame structure and NO formation. The turbulent combustion model is extended to nonadiabatic flame condition with radiation by introducing an enthalpy variable, and the radiative heat loss is calculated by a local, geometry-independent model. The effects of turbulent fluctuation are taken into account by the joint assumed PDFs. Numerical model is based on the non-orthogonal body-fitted coordinate system and the pressure/velocity coupling is handled by PISO algorithm in context with the finite volume formulation. The present PSR-based turbulent combustion model has been applied to analyze the highly intense turbulent nonpremixed flame field in the double swirler combustor. The detailed discussions were made for the flow structure, combustion effects on flow structure, flame structure, and emission characteristics in the highly intense turbulent swirling flame of the double swirler burner.

• 천문학회지
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• 제37권5호
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• pp.343-347
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• 2004

The energy injection of galactic black holes (BH) into the intergalactic medium via extragalactic radio source jets and lobes is sufficient to magnetize the IGM in the filaments and walls of Large Scale Structure at < [B] > ${\~}0.l{\mu}G$ or more. It appears that this process of galaxy-IGM feedback is the primary source of IGM cosmic rays(CR) and magnetic field energy. Large scale gravitational infall energy serves to re-heat the intergalactic magnetoplasma in localities of space and time, maintaining or amplifying the IGM magnetic field, but this can be thought of as a secondary process. I briefly review observations that confirm IGM fields around this level, describe further Faraday rotation measurements in progress, and also the observational evidence that magnetic fields in galaxy systems around z=2 were approximately as strong then, ${\~}$10 Gyr ago, as now.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1493-1498
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• 2004

WSGGM with gray gas regrouping is successfully applied to study the flame structure of counter flow flames including effect of radiative transfer. The statistical narrow band model is used to obtain the benchmark solutions. Results obtained by using the optically thin model are shown to overestimate the emission and to predict the flame structures inadequately especially for optically thick and low stretch rate flames. Computed results by using the WSGGM with 10 gray gases and SNB model show reasonable agreements with each other, and the required calculation time for the WSGGM is acceptable for engineering applications.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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• pp.260-268
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• 1997

The safety of LPG vessel storage has been simply designed and controled with blast wave barrier structure concept regardless of its quantity or hazardous situation. The limit of regal controls on LPG vessel storage need to be identified in terms of safety buffer distance from LPG explosion. The level of overpressure effect and heat radiation In the safety structure and neighbouring human activity required to be estimated to find the gap between existing controls on such storage. To this content the paper discuss the issues on the approach In the blast wave barrier and safety separation distances.

• 한국항공우주학회지
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• 제45권10호
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• pp.898-906
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• 2017

본 논문은 우주선의 우주궤도 상에서 받는 외부 열원을 효과적이고 정확하게 계산할 수 있는 방법에 대해 논한다. 우주 외부 열원은 크게 태양직사광, 지구반사광, 지구복사열 세가지로 구분할 수 있다. 본 논문은 지구반사광과 지구복사열이 확산반사 및 방사를 따른다고 가정하고 지구표면을 다수의 구역들로 분할하여 이들과 인공위성 표면과의 반사/복사열을 계산하여 합산하였다. 본 연구에는 이들의 엄밀 적분식을 적용하여 수렴성을 극대화하였으며 많은 경우 정확한 결과를 가져올 수 있음을 알 수 있다. 그리고 외부 열원과 위성 표면 사이의 광선 차폐를 판단하기 위해 KD Tree Ray Tracing을 적용한 인공위성 궤도 열하중 계산 알고리즘을 개발하였다.

• 한국대기환경학회지
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• 제30권6호
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• pp.600-618
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• 2014

The metadata for urban meteorological observation is standardized through comparison with those established at the World Meteorological Organization and the Korea Meteorological Administration to understand the surrounding environment around the sites exactly and maintain the networks and sites efficiently. It categorizes into metadata for an observational network and observational sites. The latter is again divided into the metadata for station general information, local scale information, micro scale information, and visual information in order to explain urban environment in detail. The metadata also contains the static information such as urban structure, surface cover, metabolism, communication, building density, roof type, moisture/heat sources, and traffic as well as the update information on the environment change, maintenance, replacement, and/or calibration of sensors. The standardized metadata for urban meteorological observation is applied to the Weather Information Service Engine (WISE) integrated meteorological sensor network and sites installed at Incheon area. It will be very useful for site manager as well as researchers in fields of urban meteorology, radiation, surface energy balance, anthropogenic heat, turbulence, heat storage, and boundary layer processes.

• 대기
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• 제25권2호
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• pp.193-203
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• 2015

A large aperture scintillometer (LAS) was deployed with an optical path length of 2.1 km to estimate turbulent sensible heat flux (${\mathcal{Q}}_H$) over a highly heterogeneous urban area. Scintillation measurements were conducted during cold season in November and December 2013, and the daytime data of 14 days were used in the analysis after quality control processes. The LAS-derived ${\mathcal{Q}}_H$ show reasonable temporal variation ranging $20{\sim}160W\;m^{-2}$ in unstable atmospheric conditions, and well compare with the measured net radiation. The LAS footprint analysis suggests that ${\mathcal{Q}}_H$ can be relatively high when the newly built-up urban area has high source contribution of the turbulent flux in the study area ('northwesterly winds'). Sensitivity tests show that the LAS-derived ${\mathcal{Q}}_H$ are highly sensitive to non-dimensional similarity function for temperature structure function parameter, but relatively less sensitive to surface aerodynamic parameters and meteorological variables (temperature and wind speed). A lower Bowen ratio also has a significant influence on the flux estimation. Overall uncertainty of the estimated daytime ${\mathcal{Q}}_H$ is expected within about 20% at an upper limit for the analysis data. It is also found that stable atmospheric conditions can be poorly determined when the scintillometry technique is applied over the highly heterogeneous urban area.

• 대한기계학회논문집
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• 제16권2호
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• pp.207-225
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• 1992

The study is concerned with the thermo-viscoplastic finite element analysis of axisymmetric forward hot extrusion through square dies. The problem is treated as a nonsteady state problem because the distribution of temperature and material properties are continuously changing with the punch travel. In square die extrusion, difficulties arise from the severe distortion and die interference of elements at the aperture rim of the die even with a small punch travel. And finite element computation is impossible without intermittent remeshing. Accordingly, an automatic remeshing technique is proposed by employing specially designed mesh structure near the aperture rim. The analysis of temperature distribution includes heat conduction through material interfaces, heat convection and radiation to the atmosphere and is carried out by decoupling the heat analysis from the analysis of the deformation. The extrusion load and the distributions of strain rate and temperature are computed for the given cases rendering reasonable results. Computed grid distortions are found to be in good agreement with the experimental results. It has been thus shown that the proposed method of analysis can be effectively applied to the axisymmetric hot extrusion through square dies.

• 한국방재학회지
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• 제2권4호
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• pp.40-47
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• 2002

Since it is important to understand the bio-climatic change in Seoul for ecological city planning in the future, this paper gives an overview on bio-climate analysis of urban environments at Seoul. We analyzed its characteristics in recent years using the observations of 24 of Automatic Weather Station (AWS) by Korea Meteorological Administration (KMA). In urbanization, Seoul metropolitan area is densely populated and is concentrated with high buildings. This urban activity changes land covering, which modifies the local circulation of radiation, heat and moisture, precipitation and creating a specific climate. Urban climate is evidently manifested in the phenomena of the increase of the air temperature, called urban heat Island and in addition urban sqall line of heavy rain. Since a city has its different land cover and street structure, these form their own climate character such as climate comfort zone. The thermal fold in urban area such as the heat island is produced by the change of land use and the air pollution that provide the bio-climate change of urban eco-system. The urban wind flow is the most important climate element on dispersion of air pollution, thermal effects and heavy shower. Numerical modeling indicates that the bio-climatic transition of wind wake in urban area and the dispersion of the air pollution by the simulations of the wind variation depend on the urban land cover change. The winds are separately simulated on small and micro-scale at Seoul with two kinds of kinetic model, Witrak and MUKLIMO.