• Journal of computational fluids engineering
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• v.12 no.3
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• pp.62-68
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• 2007

A conceptual thermal design is performed for the optical payload system of a geostationary satellite. The optical payload considered in this paper is GOCI(Geostationary Ocean Color Imager) of COMS of Korea. The radiative thermal control system is employed in order to expect a small thermal gradient in the telescope structure of GOCl. Two design margins are applied to the dedicated radiator dimensioning, and three kinds of configuration to the heater power sizing. A Monte-Carlo ray tracing method and a network analysis method are utilized to calculate radiative couplings and thermal responses respectively. At the level of conceptual design, sizing thresholds are presented for the radiator and heater on the purpose of determining the mass and power budget of the spacecraft.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.96.4-96
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• 2002

Thermal infrared imaging is a highly promising technology for condition monitoring and predictive maintenance of electronic, electrical and mechanical elements in nuclear power plants. However, conventional low-cost infrared imaging systems suffer from poor spatial resolution compared to commercial CCD cameras. This paper describes an approach to enhance inspection performances for calandria reactor area of Wolsung nuclear power plant through the technique of superimposing thermal infrared image into real CCD image. In the occurrence of thermal abnormalities on observation points and areas of calandria reactor area, unusual hot image taken from thermal infrared camera is mapped upon re...

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.2
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• pp.276-287
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• 1990

In this paper research result of transient thermal stress analysis of power plant turbine rotors for life prediction under severs operating conditions is presented. Galerkin's recurrence scheme is used for numerical solution of discretized FEM equation of transient heat conduction equation. Boundary conditions for the equation and operating conditions are intensively investigated for accurate life prediction of turbine rotors in operation. A computer program for on-site application is developed and tested. Distribution of thermal stress in turbine rotors during various operating condition is analyzed with the program and it is found that the peak thermal stress appears during cold stage conditions at the first stage of high pressure rotors.

• Journal of Power System Engineering
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• v.15 no.6
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• pp.5-10
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• 2011

A turbocharger is subjected to rapid temperature changes during thermal cyclic loads. In order to predict the thermo-mechanical failures, it's very important to estimate temperature distributions under the thermal shock test. This paper suggest the finite element techniques with the temperature histories, a constitutive material model and the mechanical constraints to calculate the thermal stresses and plastic strain distributions for the turbine housing. The first step was to develop a simple coupon approach to represent the failure mechanism of the classical design shapes and secondly applied the actual turbocharger to predict and validate the weak locations under the physical engine test.

• Advances in materials Research
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• v.7 no.1
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• pp.1-16
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• 2018

Thermal bifurcation buckling behavior of fully clamped Euler-Bernoulli nanobeam built of a through thickness functionally graded material is explored for the first time in the present paper. The variation of material properties of the FG nanobeam are graded along the thickness by a power-law form. Temperature dependency of the material constituents is also taken into consideration. Eringen's nonlocal elasticity model is employed to define the small-scale effects and long-range connections between the particles. The stability equations of the thermally induced FG nanobeam are derived via the principal of the minimum total potential energy and solved analytically for clamped boundary conditions, which lead for more accurate results. Moreover, the obtained buckling loads of FG nanobeam are validated with those existing works. Parametric studies are performed to examine the influences of various parameters such as power-law exponent, small scale effects and beam thickness on the critical thermal buckling load of the temperature-dependent FG nanobeams.

• Transactions of Materials Processing
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• v.17 no.5
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• pp.356-363
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• 2008

An evaluation system of the thermal properties of exothermic & insulating materials was developed. By measuring the power supply of the induction furnace, the thermal property of exothermic & insulating materials could be evaluated with high reproducibility at elevated temperature of molten steel. The thermal properties of exothermic & insulating materials were affected by mixing condition of raw materials. The effect of main components of exothermic & insulating materials such as metallic aluminum and $Fe_2O_3$ powder on the exothermic and insulating properties was examined. It could be expected to design and develop various exothermic & insulating materials by means of the evaluation system of the thermal properties.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.435-440
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• 2006

In order to understand changes of water temperature for thermal discharge of Hadong power plant in Gwangyang and Jinju Bay, it was analyzed for temperature data of representative season by MEM(Maximum entropy method) that is one of the spectral analysises. And due to understand effect of thermal discharge at each point, analyzed spectral data showed reactive energy rate of reference point by calculating energy from 24 time period to height frequency zone. As a result of spectral analysis, it showed that there were 9 points which are largely effected, 7 points which will be estimated, 6 points which is difficult to estimate, 14 points which rarely effected by thermal discharge.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.4
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• pp.377-385
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• 2015

This paper presents a thermodynamic performance analysis of regenerative organic Rankine cycle (ORC) using turbine bleeding to utilize low-grade finite thermal energy. Refrigerant R245fa was selected as the working fluid. Special attention is paid to the effects of the turbine bleeding pressure and the turbine bleed fraction on the thermodynamic performance of the system such as net power production and thermal efficiency. Results show that the thermal efficiency has an optimum value with respect to the turbine bleeding pressure and the net power production is lower than the basic ORC while the thermal efficiency is higher.

• Journal of Power System Engineering
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• v.3 no.3
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• pp.14-21
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• 1999

The wave nature of heat conduction has been developed in situations involving extreme thermal gradients, very short times, or temperatures near absolute zero. Under the excitation of a periodic surface heating in a finite medium, the hyperbolic and parabolic heat conduction equations and the damped wave equations in heat flux are presented for comparative analysis by using the Green's function with the integral transform technique. The Kummer transformation is also utilized to accelerate the rate of convergence of these solutions. On the other hand, the temperature distributions are obtained through integration of the energy conservation law with respect to time. For hyperbolic heat conduction, the heat flux distribution does not exist throughout all the region in a finite medium within the range of very short times(${\xi}<{\eta}_l$). It is shown that due to the thermal relaxation time, the hyperbolic heat conduction equation has thermal wave characteristics as the damped wave equation has wave nature.

• Journal of Power System Engineering
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• v.20 no.2
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• pp.79-84
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• 2016

The thermodynamic performance of ocean thermal energy conversion with 1 kg/s geothermal water flow rate as a heat source was evaluated to obtain the basic data for the optimal design of cycle with respect to the classification of the working fluid. The basic thermodynamic model for cycle is rankine cycle and the geothermal water and deep seawater were adapted for the heat source of evaporator and condenser, respectively. R245fa, R134a are better to use as a working fluid than others in view of the use of geothermal water. It is important to select the proper working fluid to operate the ocean thermal energy conversion. So, this paper can be used as the basic data for the design of ocean thermal energy conversion with geothermal water and deep seawater.