• Journal of the Korean Physical Society
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• 제73권10호
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• pp.1541-1545
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• 2018

We study lattice thermal conductivity of $Sb_2Te_3$ using molecular dynamics simulations. The interatomic potentials are fitted to reproduce total energy and elastic constants, and phonon properties calculated using the potentials are in reasonable agreement with first-principles calculations and experimental data. Our calculated lattice thermal conductivities of $Sb_2Te_3$ decrease with temperature from 150 K to 500 K. The in-plane lattice thermal conductivity of $Sb_2Te_3$ is higher than cross-plane lattice thermal conductivity of $Sb_2Te_3$, as in the case of $Bi_2Te_3$, which is consistent with the anisotropy of the elastic constants.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.932-939
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• 2011

This paper deal with technique of tension length calculation for 350km/h high speed catenary system. Tension length affects in facility investment. Possibility of overlap increasing a tension length and the equipment investor decreases in order to decrease. Considers the parameter which specifies and the grudge which is possible long the fact that decides a tension length is the aim which is important plans overhead contact line. The element which decides a tension length with next following; (i) Operating range of tension device, (ii) Change of the horizontal tension which affects possibility of the effect which operates to the line and span, (iii) Tension of wire material the tensile force which is relation, (iv) Wire thermal expantion which relates with a standard temperature, (v) Curve radius, (vi) Wind velocity, (vii) Thermal range of overhead contact wire and mechanical design of tension mechanism etc.

• 전력전자학회논문지
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• 제21권5호
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• pp.442-448
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• 2016

This paper presents electromagnetic force effect of the conductor and insulator in the HVDC valve hall. This paper is based on IEC 60865, which is applicable to the mechanical and thermal effects of short-circuit currents. The paper contains procedures for the calculation of the electromagnetic effect on HVDC conductors and flexible conductors, as well as the thermal effect on HVDC conductors. The results are applied to the Godeok -Dangjin HVDC system.

• Nuclear Engineering and Technology
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• 제37권5호
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• pp.469-478
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• 2005

The subchannel analysis capability of MARS, a multi-dimensional thermal-hydraulic system code, has been enhanced. In particular, the turbulent mixing and void drift models for the flow-mixing phenomena in rod bundles were improved. Then, the subchannel analysis feature was combined with the existing coupled system thermal-hydraulics (T/H) and 3D reactor kinetics calculation capability of MARS. These features allow for more realistic simulations of both the hot channel behavior and the global system T/H behavior. Using the coupled features of MARS, a coupled analysis of a main steam line break (MSLB) is carried out for demonstration purposes. The results of the calculations are very reasonable and promising.

• KEPCO Journal on Electric Power and Energy
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• 제3권2호
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• pp.119-125
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• 2017

Regarding the implementation of ROMM project (Rehabilitation, Operation, Maintenance & Management), which is one of overseas development projects, it is very important to diagnose the exact current status of aged thermal power plant. However, when people visit the power plant for the purpose of prediagnosis to implement the ROMM project, most target power plants for diagnosis, in general, are under operation. This can be a big interference factor to diagnose the exact current status of power plants. Therefore, in order to solve such interference factor, based on the 30 years of know-how in the field, the present study has developed a regression curve for a simple life time assessment and the calculation of rehabilitation cost that may be used as a reference relatively for the quantitative diagnosis on the status of a relevant power plant even during the operation of the power plant.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.446-447
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• 2008

In this paper, a calculation method of the short-time emergency by considering a initial load level and overload time is presented. short-time emergency analyze transient thermal rating and Long-time emergency analyze steady-state thermal rating. Using the suggested method in the paper, increasing the short-term allowable current.

• 대한기계학회논문집B
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• 제22권7호
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• pp.905-914
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• 1998

View factor determination is very important in thermal analysis problems with surface radiation but it is very difficult to determine view factors for complex geometries. Exact calculation of view factors for crystal growth furnace is essential due to not only its high surface temperature but the radiation shield, complicated heating system. In this study, view factor calculation algorithm is introduced and applied to cylindrical crystal growth furnace. This algorithm is based on the Hemi-Cube Algorithm and the results obtained with this algorithm show good agreements with those of analytical solution. As an application of this algorithm, temperature profiles and heating value distributions for various furnaces are calculated and the shape criteria for better furnace are suggested.

• International Journal of Aeronautical and Space Sciences
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• 제1권2호
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• pp.22-29
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• 2000

A method to simulate the gas turbine transient behavior is developed. The basic principles of the method and main input data required are described. Calculation results are presented in terms of whole operating regime of the engine. The influence of initial parameters such as starting engine power, moment of inertia of the rotor, fuel schedule on performance characteristics of gas turbine during transient operation is shown. In addition, the effect of bleeding air on transient behavior is also considered. For validation of the developed computer code, a comparative analysis with experimental data obtained from a heavy duty gas turbine is made. Calculation results agree well with the experimental data for the range of operating regime studied and proved applicability of the developed technique to initial design stage of control system.

• 소성∙가공
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• 제25권4호
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• pp.242-247
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• 2016

CFD simulation with FlowVision^® is used to evaluate the capability of cooling channel in hot press forming dies. Two different types of cooling channels, dry drilled and pocket types are considered for comparison. Two different approaches for simulating cooling channel are considered. One is single-phase velocity calculation for coolant only and the other is multiphase thermal and velocity calculation for die, blank and coolant all together. Both approaches show better cooling performance in pocket type cooling channel. Also both approaches show their own effectiveness in designing cooling channel of hot press forming dies.

• 한국의류학회지
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• 제21권7호
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• pp.1153-1161
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• 1997

The insulation provided by clothing system is usually expressed in terms of a coo units and its distribution of the body, directly affect convective, conductive, and radiant heat loss from the skin to the environment Evaporated heat loss is dependent upon fabric permeability, the amount of body surface area covered by clothing, and the pumping of air between the body and garment layers. Persons at low to medium activity levels, dressed in conventional apparel in door environments, usually do not lose a large amount of heat through evaporation. Thermal manikin technology is used to measure the resistance to heat transfer provided by clothing systems. The reciprocal of this value, 6.45 W/m2.$^{\circ}C$ is often used in calculations for convenience. The purpose of this study was to implement a research program for calculation the insulation value (clo), body surface area and basal metabolic rate of selected clothing system. The project provided for the building of an insulation data base for use in evaluating and comparing new and improved garments.