• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.1
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• pp.133-142
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• 2001

Investigation on ignition and flame propagation of pyrolyzing fuel in a cylindrical enclosure is accomplished. The pyrolyzing fuel of cylindrical shape is located in an outer cylinder sustained at high-temperature. Due to gravity, the buoyancy motion is inevitably incurred in the enclosure and this affects the flame initiation and propagation behavior. The radiative heat transfer plays an important role since a high temperature difference is involved in the problem. Therefore in all cases presented here, the intrinsic radiation effects are considered. Numerical studies have been performed over various governing parameters, such as Grashof number, overheat ratio, and vertical fuel eccentricity. Depending on the Grashof number, the flame behavior is found to be totally different: a separated visible flame appears as the Grashof number reaches 10(sup)7. The location of flame onset is also affected by the vertical eccentricity of inner pyrolyzing fuel as well as thermal conditions applied.

• Steel and Composite Structures
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• v.34 no.6
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• pp.819-835
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• 2020

The effects of atmospheric thermal loads on the response of structural elements that are exposed to open environments have been recognized by research works and design specifications. The main source of atmospheric heat is solar radiation, which dominates the variation of the temperature of air, earth surface and all exposed objects. The temperature distribution along the depth of steel members may differ with the geometry configuration, which means that the different-configuration steel members may suffer different thermally induced strains and stresses. In this research, an experimental steel beam was instrumented with many thermocouples in addition to other sensors. Surface temperatures, air temperature, solar radiation and wind speed measurements were recorded continuously for 21 summer days. Based on a finite element thermal analysis, which was verified using the experimental records, several parametric studies were directed to investigate the effect of the geometrical parameters of AISC standard steel sections on their thermal response. The results showed that the overall size of the beam, its depth and the thickness of its elements are of significant effect on vertical temperature distributions and temperature differences.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.9
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• pp.2916-2923
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• 1996

A numerical analysis of the moving bed heat exchanger of solid particles inside the vertical pipe was performed using finite difference method. Also, the theoretical solutions were obtained for comparison when the wall heat flux or the wall temperature was assumed constant. The comparison showed that their results agreed well each other. The moving bed heat exchanger was classified as countercurrent-flow, parallel-flow, and cross-flow types according to the gas flow direction. For each type, the thermal efficiency of heat exchanger was calculated as a function of non-dimensional parameters such as the characteristic length of heat exchanger, Biot number and the ratio of thermal capacities of gas and solid particles.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3164-3169
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• 2013

In this study, a series of CFD analysis was performed in order to predict the leaving water temperature and the slope of in-situ thermal response tests of the vertical-type geothermal heat exchangers. The geothermal heat exchanger and surrounding ground formation were modeled using GAMBIT and simulation was used by utilizing FLUENT which is commercial CFD code. Comparing with the results of CFD and in-situ thermal response tests, the results of CFD was presented good agreement with $0.5^{\circ}C$ difference of Leaving Water Temperature and with 1.6% difference of the Slope.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.9
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• pp.810-816
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• 2000

Thermal comfort plays an important role in modern office buildings. Four major factors affecting thermal comfort are air temperature, velocity, humidity and radiation temperature. Distribution of these thermal factors in indoor space depends largely on the air flow which is related to the method of supplying and extracting air. In this study, an experimental analysis on indoor thermal comfort is conducted to study the difference between a ceiling supply cooling system and a floor supply one. The two cooling systems are applied to an office space during summer season and the distributions of temperature, velocity, radiation temperature and PMV are measured. Results show that the floor supply cooling system is superior in terms of thermal comfort and energy saving. Studies need to be done, however, to reduce the vertical temperature difference of a floor supply air conditioning system.

• Journal of Environmental Science International
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• v.19 no.2
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• pp.171-184
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• 2010

Accurate simulation of the meteorological field is very important to assess the wind resources. Some researchers showed that sea surface temperature (SST) plays a leading role on the local meterological simulation. New Generation Sea Surface Temperature (NGSST), Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA), and Real-Time Global Sea Surface Temperature (RTG SST) have different spatial distribution near the coast and OSTIA shows the best accuracy compared with buoy data in the southeastern coast of the Korean Peninsula. Those SST products are used to initialize the Weather Research and Forecasting (WRF) Model for November 13-23 2008. The simulation of OSTIA shows better result in comparison with NGSST and RTG SST. NGSST shows a large difference with OSTIA in horizontal and vertical wind fields during the weak synoptic condition, but wind power density shows a large difference during strong synoptic condition. RTG SST shows the similar patterns but smaller the magnitude and the extent.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.685-691
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• 2022

This study was based on the steel composite concrete box structure (Transfer girder) which was installed to support the skyscrapers directly above the subway line. In this study, it was analytically proved that the cause of cracks on the steel composite concrete box structure were the shrinkage cracks by comparing the results of crack investigation and numerical analysis. As the results, it was found that the internal temperature difference between concrete and steel members occurred according to the shape of the steel frame embedded in concrete, the location of vertical stiffener, and the closed section area. The narrower spacing of vertical stiffener was occurred the internal temperature concentration of the structure and the temperature difference increased. And the location of higher thermal strain and temperature were similar to the location of actual cracks by the visual inspection. Therefore, the internal temperature concentration parts were formed according to the presence and spacing of the vertical stiffeners and the inspection passage in the central part of the structure. The shrinkage cracks were occurred by the restrained of temperature expansion and contraction of the concrete. As the results of this study, it was important to separate and manage the non-structural cracks caused by shrinkage and the structural cracks in the maintenance of serviced steel-composite concrete structures.

• Journal of Wetlands Research
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• v.13 no.2
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• pp.265-273
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• 2011

Hyporheic zone, where groundwater-stream water mixing occurs, sensitively responds to heat of groundwater and stream water temperature. Variation of stream water temperature has short time period and time dependent, because stream water temperature is influenced by daily fluctuation and seasonal air temperature. On the other hand, groundwater temperature is insignificant. In this study, we conducted 1-dimensional heat transfer analysis. The results show that there are differences of temperature distribution between gaining stream and losing stream with flux in hyporheic zone. Especially, variations of hyporheic water temperature show a significant difference in adjacent streambed, Also, the results shows that distribution of temperature was more affected by groundwater direction than intensity of flux.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.648-653
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• 2001

This study represents the numerical analysis of natural convection of a microenvironments with a air permeability in the clothing air-layer. The clothing air layer of shoulder and arm was used for numerical analysis model. As a numerical analysis method, we adopted a finite volume method for two-dimensional laminar flow, and analyzed the flow and thermal characteristics of velocity, temperature and concentration in the air layer between body and clothing. As a temperature boundary conditions, we considered that a body skin has a high temperature with $34^{\circ}C$ the environmental temperatures are $5,\;15\;and\;25^{\circ}C$ for various permeability coefficients. The distributions of concentration, temperature and velocity were showed that two large cells were. formed at horizontal and vertical air layer, respectively. As the temperature difference between body skin and environment decrease, the heat transfer was decreased rapidly.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.12
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• pp.1282-1287
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• 2001

This study presents the numerical analysis of natural convection of a micro- environments with air permeability in the clothing air-layer. As a numerical model the clothing air layer of shoulder and arm were adopted. Finite volume method for two-dimensional laminar flow was used for the analysis of flow and thermal characteristics of velocity, temperature and concentration in the air layer between body and clothing. As temperature boundary conditions, a body skin has a high temperature with $34^{\circ}C$ and the environmental temperatures are 5, 15 and $25^{\circ}C$ for various permeability coefficients. The distributions of concentration, temperature and velocity are shown that two large cells form at horizontal and vertical air layer, respectively. As the temperature difference between body skin and environment decreases, the heat transfer is decreased rapidly.