• Tunnel and Underground Space
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• v.17 no.4
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• pp.301-310
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• 2007

The prediction of temperature in the workings for the propriety examination for the development of a deep coal bed and the ventilation design is fairly important. It is quite demanding to obtain precise thermal conductivity of rock due to the variety and the complexity of the rock types contiguous to the coal bed. Therefore, to estimate the thermal conductivity corresponding to this geological situation and complex gallery conditions, a computing program which is TemPredict, is developed in this study. It employs Artificial Neural Network and calculates the climatic conditions in galleries. This advanced neural network is based upon the Back-Propagation Algorithm and composed of the input layers that are acceptant of the physical and geological factors of the coal bed and the hidden layers each of which has the 5 and 3 neurons. To verify TemPredict, the calculated result is compared with the measured one at the entrance of -300 ML 9X of Jang-sung production department, Jang-sung Coal Mine. The difference between the results calculated by TemPredict ($25.65^{\circ}C$) and measured ($25.7^{\circ}C$) is only $0.05^{\circ}C$, which is less than the allowable error 5%. The result has more than 95% of very high reliability. The temperature prediction for the main carriage gallery 9X in -425 ML under construction when it is completed is made. Its result is $28.2^{\circ}C$. In the future, it would contribute to the ventilation design for the mine and the underground structures.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.28-35
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• 2016

The in-situ thermal response test for the design of a ground heat exchanger of geothermal heat pumps have difficulty in predicting the outlet temperature according to the variation of conditions due to the expense and time. This paper suggests a 3-D CFD analysis method to predict the heat transfer performance of vertical type ground heat exchanger, which is mostly used in national, and the outlet temperature and the slope of two in-situ thermal response tests were compared to test the proposed CFD reliability. The results of CFD analysis showed that the outlet temperature was predicted to within $0.5^{\circ}C$ of the actual value and the slope was predicted to within 1.6%. The reliability of the CFD analysis method was confirmed using this process, and the outlet temperature prediction of the two in-situ thermal response tests was obtained by changing ${\pm}20%$ of the flow rate and the effective thermal conductivity conditions, respectively. The results of CFD analysis showed that the outlet temperature of Case 1 was 28.0 (-20%) and $29.6^{\circ}C$ (+20%) for the flow rate variation and $29.6^{\circ}C$ (-20%) and $28.0^{\circ}C$ (+20%) for the effective thermal conductivity variation, and the outlet temperature of Case 2 was 28.4 (-20%) and $29.8^{\circ}C$ (+20%) for the flow rate variation and $29.7^{\circ}C$(-20%) and $28.4^{\circ}C$(+20%) for the effective thermal conductivity variation.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.12 no.3
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• pp.159-169
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• 1983

The thermal Conductivities along the position of spherical shaped fruits, such as, apple, mandarine orange. citrus hagyul were predicted by the analysis of the cooling curves obtained by the hydrocooling procedure using ice water. The thermal conductivity was independent of temperature. The thermal conductivities along the position of the fruits were nearly constant, but their small deviations were inherited by the improper spherical shape and the heterogenous structural composition of the fruits. The thermal conductivities of apple, mandarine orange, and citrus hagyul were found to be 0.353, 0.430, and $0.397\;Kcal/mh^{\circ}C$, respectively.

• Journal of Biosystems Engineering
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• v.33 no.1
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• pp.21-29
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• 2008

In this study, the thermal properties of peeled chestnuts were measured, and the mathematical prediction model of freezing time was also developed for various interior positions from center to rind (surface). The measured thermal properties were showed that heat conductivity is $0.43W/m^{\circ}C$, specific heat is $2.7206J/m^3^{\circ}C$, latent heat is $216.9{\times}10^6J/m^3$ and freezing point is $-2.8^{\circ}C$. The entire process about reaching to the freezing time of peeled chestnuts was analyzed with its each regular depth position using the finite difference method (FDM) based on computer simulation. In case of regular freezing temperature, it was showed an that surface (rind) position is more rapidly reached into the freezing point rather than the center position, and also reaching time to the freezing point is more fast at the lower freezing temperature. Comparison results between simulation and experiments showed linear relationship. In regularly varying condition for freezing temperature, this method would give an information to predict a freezing time of the interior points for peeled chestnuts and more similar agricultural products.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.1
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• pp.59-65
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• 1993

In a spark ignition engine, in order to make research on flame propagation, attentive concentration should be paid on initial combustion stage about the formation and development of flame. In addition, the initial stage of combustion governs overall combustion period in a spark ignition engine. With the increase of the size of flame kernel, it could reach initial flame stage easily, and the mixture could proceed to the combustion of stabilized state. Therefore, we must study the theoretical calculation of minimum flame kernel radius which effects on the formation and development of kernel. To calculate the minimum flame kernel radius, we must know the thermal conductivity, flame temperature, laminar burning velocity and etc. The thermal conductivity is derived from the molecular kinetic theory, the flame temperature from the chemical reaction equations and the laminar burning velocity from the D.K.Kuehl's formula. In order to estimate the correctness of the theoretically calculated minimum flame kernel radius, the researcheres compared it with the RMaly's experimental values.

• The Korean Journal of Food And Nutrition
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• v.17 no.1
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• pp.32-40
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• 2004

This Study was conducted to predict temperature profile of Jangjorim (boiled beef in soy sauce) food during retorting using the commercial NISA (Numerical Integrated Elements for System Analysis) program. NISA program is a good tool to simulate the temperature profile of a specific material based upon the finite element method. The cold point of Jangjorim food located not at the geometrical center but at 26.9 mm backward in y plane because specific heat of soy sauce was 20% higher than that of boiled beef. The effects of heat transfer coefficients on heat transfer during retorting process of Jangjorim were analyzed by response surface methodology (RSM). Independent variables were thermal conductivity of soy sauce, thermal conductivity of boiled beef, and convection heat transfer coefficient and dependent variables were temperature error and lethality error. Thermal conductivity of soy sauce was the most significant contributor among those (P<0.01).

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.2
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• pp.99-112
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• 2015

In this study, laboratory test equipment was designed and installed to evaluate the thermal behavior of bentonite, which is used as a buffer in high-level waste disposal systems. The thermal analysis was conducted to verify the test results using ABAQUS, a finite element analysis code. In view of the seasonal changes seen during the test, the thermal behavior of bentonite with a temperature of outside air was evaluated. Of the cases examined, the results of the analysis model using stainless steel (Case 3) approximates to the test results, showing an error of about 1℃. The results of the thermal analysis into seasonal temperature distributions are consistent with trends seen in lab-test results. These analyses show that the effects of the thermal conductivity of the material surrounding the buffer and outside air temperature, are very important factors in the thermal behavior of bentonite. In the future, it is expected that a moisture saturation test of a bentonite buffer containing a heat source will be carried out. Therefore, the development of a numerical analysis model is required for the prediction and verification of the laboratory test results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.4
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• pp.347-355
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• 2014

Thermal problems that are directly related to the lifetime of an electronic device are becoming increasingly important owing to the miniaturization of electronic devices. To solve thermal problems, it is essential to study thermal stability through thermal diffusion and insulation. A honeycomb sandwich plate has anisotropic thermal conductivity. To analyze the thermal deformation and temperature distribution of a system that employs a honeycomb sandwich plate, the thermal and elastic properties need to be determined. In this study, the thermal and elastic properties of a honeycomb sandwich plate, such as thermal conductivity, coefficient of thermal expansion, elastic modulus, Poisson's ratio, and shear modulus, are predicted. The properties of a honeycomb sandwich plate vary according to the hexagon size, thickness, and material properties.

• Laser Solutions
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• v.11 no.4
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• pp.13-20
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• 2008

The damage threshold measurement of gold films is carried out with ultrashort-pulse laser. An enhanced two temperature model is developed to encounter the limitation of linear modeling during ultrashort pulse laser ablation. In which the electron heat capacity is calculated using a quantum mechanical approach based on a Fermi-Dirac distribution, temperature-dependent electron thermal conductivity valid beyond the Fermi temperature is adopted, and reflectivity and absorption coefficient are estimated by applying a temperature-dependent electron relaxation time. The predicted damage threshold using the proposed enhanced modelclosely agreed with experimental results, demonstrating the importance of considering transient thermal and optical properties in the modeling of ultrashort pulse laser ablation.

• Journal of the Korean Geotechnical Society
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• v.33 no.7
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• pp.55-64
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• 2017

A geological repository has been considered one of the most adequate options for the disposal of high-level radioactive waste. A geological repository will be constructed in a host rock at a depth of 500~1,000 meters below the ground surface. The geological repository system consists of a disposal canister with packed spent fuel, buffer material, backfill material, and intact rock. The buffer is very important to assure the disposal safety of high-level radioactive waste. It can restrain the release of radionuclide and protect the canister from the inflow of groundwater. High temperature in a disposal canister is released into the surrounding buffer material, and thus the thermal transfer behavior of the buffer material is very important to analyze the entire disposal safety. Therefore, this paper presents a thermal conductivity prediction model for the Kyungju compacted bentonite buffer material which is the only bentonite produced in Korea. Thermal conductivity of Kyungju bentonite was measured using a hot wire method according to various water contents and dry densities. With 39 data obtained by the hot wire method, a regression model to predict the thermal conductivity of Kyungju bentonite was suggested.