• Journal of the Korean Institute of Rural Architecture
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• v.16 no.1
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• pp.35-42
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• 2014

Due to the development of civilization, the humans is privileged the rich of technologies for housing thermal environment. But, this kind of technological development caused enough trouble of energy excessive consumption. For solve this problem, many researchers strive to exploit the low energy sustainable techniques. For such a reason, the eco-friendly techniques of vernacular house are resurfacing. These traditional techniques are applied to a development of eco-friendly modern housing. They are no longer recognized as outdated products. On this context, this study proposes an scientific analysis on the thermal environment characteristics of Neolithic thatched-roof dugout hut(Um house). So far the several studies have been carried out in viewpoint of the history and structural compositions of the Um house which has been used as the normal housing for about 1000 years in the Neolithic era, however the thermal characteristics analysis of the Um house has never been studied. Um house is not a housing which has been composed by the scientific analysis or architectural design technology, but evolved empirically over a long period. This study on the thermal environment characteristics of Um house would provide basic information for the development of korean eco-friendly rural housing by korean climate characteristics. In this study, the thermal environmental characteristics of the Um house in the Neolithic era was analysed experimentally. The results of this study could be summarized as follows: 1. When the solar insolation and the ambient temperature in the daytime were $420W/m^2$ and $17^{\circ}C$ respectively, the surface temperature of the Um house roof covered with the rice straw was $37^{\circ}C$ and that in the roof $32^{\circ}C$, and in the conditions above the air temperature in the room was $15^{\circ}C$. 2. When the ambient relative humidity was 40%, that in the room of the Um house 50%, and at the ambient relative humidity of 90~100%, that in the room was 60%. 3. Through the experimental analysis, it was verified that the enthalpy and relative humidity is in an inverse relationship. 4. In general the comfort degree in the living space is changed with the seasonal climate, also in this study, the comfort degree in the room of the Um house in October and November was higher than that in May and June.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.11-15
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• 2002

This paper presents the thermal characteristic analysis of a high-speed HMC with spindle speed of 50,000rpm. The spindle is supported by two radial and axial magnetic bearings. and the built-in motor is located between the axial and rear radial magnetic bearings. The X-axis and Y-axis feeding systems are composed of linear motor and linear motion guides, and the Z-axis feeding system is composed of servo-motor, ballscrew and linear motion guide. The thermal analysis model of high-speed HMC is constructed by the finite element method, and the thermal characteristics in the design stage are estimated based on the temperature distribution and thermal deformation under the conditions related to the heat generation of built-in motor, magnetic bearings, linear motors, servo-motor, ballscrew, and so on.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.1023-1027
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• 2000

In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. This paper models of the thermal errors for error analysis and develops on-the-machine measurement system by which the volumetric error are measured and compensated. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses, a designed spherical ball artifact, and five gap sensors. In order to analyze the thermal characteristics under several operating conditions, experiments performed with the touch probe unit and five gap sensors on the vertical and horizontal machining centers.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.1
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• pp.51-60
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• 2012

Optimization procedures of performance analysis for ORC(Organic Rankine Cycle) system are established to the characteristics of low temperature heat sources such as open-type and closed-type. Effective heat recovery and heat extraction related to maximum power of the cycle as well as heat quality and thermal efficiency must be considered in the case of the open-type low temperature heat source. On the other hand, in the case of the closed-type low temperature heat source, only thermal efficiency is important due to constant heat input. In this study, thermal efficiency and exergy efficiency representing a level of close to Carnot cycle are studied, as useful index for the optimization of the ORC system. To validate the results of cycle analysis, those are compared with appropriate experimental data of ORC system as a thermal efficiency point of view.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.2
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• pp.141-147
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• 2015

This paper deals with thermal characteristic analysis of induction motors for machine tool spindle for motion error prediction. Firstly, the inverse design of general induction motors for machine tool spindle has been performed by design principles. Characteristics considering VVVF inverter of induction motors were analyzed. Secondary, power loss and thermal characteristics of induction motors analyzed by equivalent thermal resistance model from Motor-CAD S/W. To develop a second-order fitted power-loss distribution model for the constant-torque operating range of the induction motor, we employed the design of experiment and response surface methodology techniques. Finally, the analysis results were experimentally verified, and the validity of the proposed analysis method was confirmed.

• Design & Manufacturing
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• v.16 no.2
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• pp.46-52
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• 2022

As the consumer market in the eco-friendly vehicle industry grows, the demand for water pump in a electric car parts market. This study intend to propose a mathematical model that can verify the effect of improving thermal properties when a non-conductive cooling filler liquid is introduced into an electric vehicle water pump. Also, the pros and cons of the immersion cooling method and future development way were suggested by analyzing the cooling characteristics using on the derived analysis solution. Thermal characteristics analysis of electric water pump applied with non-conductive filler liquid was carried out, and the diffusion boundary condition in the motor body and the boundary condition the inside pump were expressed as a geometric model. As a result of analyzing the temperature change for the heat source of the natural convection method and the heat conduction method, the natural convection method has difficulty in dissipating heat because no decrease in temperature due to heat release was found even after 300 sec. Also, it can be seen that the heat dissipation effect was obtained even though the non-conductive filling liquid was applied at the 120 sec and 180 sec in the heat conduction method. It has proposed to minimize thermal embrittlement and lower motor torque by injecting a non-conductive filler liquid into the motor body and designing a partition wall thickness of 2.5 mm or less.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.6
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• pp.59-71
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• 2019

The numerical analysis of ablative thermal protection systems (TPS) for solid rockets has been carried out with various in-house codes since the 1960s. However, the application scope of commercial codes has been expanded by adding subroutines and user-defined functions (UDF) to codes such as Fluent, Marc, and ABAQUS. In the past, the flow, thermal response and structural analysis of TPS have been performed using separate approaches. Recently, research has been conducted to interrelate them. In this paper, the thermal response characteristics of thermal protection materials, the in-house codes for thermal response analysis, and the research trends of flow-thermal-structure analysis of TPS using commercial codes were reviewed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.12
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• pp.34-41
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• 2011

In order to understand the thermal performance of each LED chips in multi-chip LED package, a quantitative parametric analysis of the temperature evolution was investigated by thermal transient analysis. TSP (Temperature Sensitive Parameter) value was measured and the junction temperature was predicted. Thermal resistance between the p-n junction and the ambient was obtained from the structure function with the junction temperature evolution during the cooling period of LED. The results showed that, the thermal resistance of the each LED chips in 4 chip-LED package was higher than that of single chip- LED package.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.396-400
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• 2003

This paper has studied thermal characteristics of machine tool to develope high speed spindle and optimum design condidering the thermal deformation. Comparing the test data of temperature measurement and structural analysis data using FEM, we verifiedthe test validity and predicted thermal deformation, influence of spindle generation of heat, and established cooling system to prevent the thermal deformation. 1) The temperature rise of spindle system depends on increasing number of rotation and shows sudden doubling increment of number of rotation over 7,000rpm. 2) Oil jacket cooling can be effective cooling method below 8,000rpm but, over 8,000rpm, it shows the decrement of cooling effect. 3) Comparing FEM analysis results and revolution test results, we can confirmn approximate temperature change consequently, it is possible to simulate temperature rise and thermal distribution on the inside of spindle system. 4) We can confirm that simulated approach by FEM analysis can be effective method in thermal-appropriate design..

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.498-503
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• 2002

This paper has studied thermal characteristics of machine tool to develope high speed spindle and optimum design considering the thermal deformation. Comparing the test data of temperature measurement and structural analysis data using FEM, we verified the test validity and predicted thermal deformation, influence of spindle generation of heat, and established cooling system to prevent the thermal deformation. 1) The temperature rise of spindle system depends on increasing number of rotation and shows sudden doubling increment of number of rotation over 7,000rpm. 2) Oil jacket cooling can be effective cooling method below 8,000rpm but, over 8,000rpm, it shows the decrement of cooling effect. 3) Comparing FEM analysis results and revolution test results, we can confirmn approximate temperature change consequently, it is possible to simulate temperature rise and thermal distribution on the inside of spindle system. 4) We can confirm that simulated approach by FEM analysis can be effective mettled in thermal-appropriate design.