• Journal of Surface Science and Engineering
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• v.50 no.6
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• pp.465-472
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• 2017

The ingot fabrication conditions related with the thermal shock bearing phase and microstructure have investigated for the rare earth zirconate ceramic material, lanthanum gadolinium zirconate, as a thermal barrier coating using electron beam evaporation method. The thermal shock resistance of the prepared ingot was evaluated by high energy electron beam irradiation. The rare earth zirconate ceramic powder was prepared by controlling the raw material powder composition of $La_2O_3$, $Gd_2O_3$ and $ZrO_2$ so as to have a composition of $(La_{0.3}Gd_{0.7})_2Zr_2O_7$ which was selected from the former study. Ingot samples were prepared under two conditions. The first condition is prepared by sintering the prepared powder mixture to form an ingot. The second condition is prepared by calcining the prepared powder mixture to form a composite phase and then sintering to form an ingot. X-ray diffraction(XRD) and Scanning Electron Microscope(SEM) were used to analyze phase forming behavior and microstructure of ingot samples. Nanoindentation method used to obtain elastic modulus and hardness of each ingot specimen. Also the stress distribution of ingot was simulated by using FEM method assuming the ingot surface was exposed to electron beam. As a results, in the case of an ingot having a network-shaped microstructure in which relatively coarse pores are included, it seems that the thermal shock resistance was higher than in the case of an ingot having a microstructure composed of relatively fine grains only or particles with the similar level size when the high energy electron beam irradiation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.4
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• pp.570-578
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• 1997

At design stage of new motor or when taking remedial action of old motor, a lot of information can be obtained from thermal parameters analysis. This study focused on the temperature rise of TEFC induction motor with respect to various thermal parameters. Frame heat transfer had the most important effect on coil temperature rise. But those of air gap and rotor fan had no effect. This fact shows fan action is more important than fin action in the case of rotor fan. Coil temperature can be more decreased by cooling near the heat sources than any other parts from the results of thermal conductivity and loss tests. Variation of cooling air flow rate and motor volume effects on coil temperature were also tested. These tests suggest that improvement of cooling fan performance is important in reducing the coil temperature rise. Thermal equivalent program was verified by comparison of some experimental results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.3
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• pp.457-472
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• 1997

We studied the temperature distribution and heat transfer characteristics of TEFC induction motor with thermal network program for more efficient design and better cooling performance of it. We knew the characteristics and the windage loss of outer cooling fan from fan test experiments. Frame axial and peripheral heat transfer coefficients and endwinding heat transfer coefficient were measured by various model experiments and then, compared with other experimental results. Frame was the main heat transfer surface, load-side and fan-side surface were not thermally symmetric from the heat flux distribution analysis. Steady and unsteady temperature distributions were measured by real motor experiments. From the results, we knew that rotor surface temperature was higher than coil temperature and the hottest spot in the coil was loadside endwinding outside surface. We compared the simulation results with those of real motor test and the two results showed a good agreement.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1727-1731
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• 2004

We propose an ART2 neural network-based fault diagnosis method to diagnose of sensor in the gas monitoring system. In the proposed method, using thermal modulation of operating temperature of sensor, the signal patterns are extracted from the voltage of load resistance. Also, fault classifier by ART2 NN (adaptive resonance theory 2 neural network) with uneven vigilance parameters is used for fault isolation. The performances of the proposed fault diagnosis method are shown by simulation results using real data obtained from the gas monitoring system.

• Journal of Electrical Engineering and Technology
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• v.3 no.1
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• pp.115-120
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• 2008

Use of the carbon nanotube is superior to general powder state materials of mechanical and electrical properties. Because its ratio of diameter and length (aspect ratio) is very large, it has been known as a type of ideal nano-reinforcement material. Based on this advantage, the existing carbon black of semiconductive shield materials used in power cables can acquire excellent properties by using a small amount of carbon nanotubes. Thus, we investigated the thermal properties of the carbon nanotube, such as thermal conductivity, specific heat, and DSC (Differential Scanning Calorimetry). We found that a high thermal resistance level is demonstrated by using a small amount of carbon nanotubes. As a result, this tendency confirms high cross-linking density in a new network in which the carbon nanotube between carbon black constitute molecules shows a bond by similar constructive properties.

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.1034-1040
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• 1997

Temperature distribution of battery module consists of 11 batteries of 90Ah rate is analyzed using commercial software NISA II. Equivalent thermal resistance network is used to reduce the number of element in calculating heat transfer through a medium composed of several different thermal conductivity layers. Orthotropic model is used to put different thermal conductivity values according to Cartesian coordinate. Aluminum cooling fins are inserted in the middle of batteries to reduce battery module temperature. The cooling fin at the end of the module does not necessary in reducing maximum temperature. Combined effect of front and side cooling fin is analyzed to reduce the temperature difference among batteries. The maximum temperature difference among batteries is reduced within $3^{\circ}C$ when 4 aluminum cooling tin of 1mm thickness is inserted in battery module.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.8
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• pp.798-804
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• 2009

A high-resolution electro-optical camera system, EOS-C, is under development in Satrec Initiative. This system is the mission payload of a 400-kg Earth observation satellite. We designed this system to give improved opto-mechanical and thermal performance compared with a similar camera system to be flown on the DubaiSat-1 system. The thermal control subsystem (TCS) of the EOS-C system uses heaters to meet the opto-mechanical requirements during in-orbit operation and it uses different thermal coating materials and multi-layer insulation (MLI) blankets to minimize the heater power consumption. We performed its thermal analysis for the mission orbit using a thermal analysis model and the result shows that its TCS satisfies the design requirements.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.2
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• pp.77-81
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• 2004

In this paper, multi-functional measurement module for RTD and 4-20mA Analog input is presented. As you know, In many industry field, RTD has been used for measuring a temperature. Although It have good properties such as wide measurement range, accuracy, the hardware or software compensation methods were applied to better linearity in many applications. According to this paper, a simply approximation method and various measuring technique are proposed to compensate large lead's resistance influence in RTD temperature measurements. As the experiment and simulation results, it is proved that the proposed method has good performance of measuring temperature. Additionally, with the CAN based communication, remote monitoring and parameter setting functions are realized.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.05a
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• pp.59-62
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• 1993

This Paper studies on thermal oxidation of alumina filled epoxy network polymer used in Extra-High voltage application. The thermal oxidation of surface has investigated by yellow index variation and various electrical properties which are surface resistivity, tracking resistance and AC dielectric strength are estimated by yellow index.

• Journal of Sensor Science and Technology
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• v.22 no.4
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• pp.302-307
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• 2013

The Sb-doped $SnO_2$ nanowire network sensors were prepared by thermal evaporation of the mixtures between tin and antimony powders. Pure $SnO_2$ nanowire networks showed high sensor resistance in air ($99M{\Omega}$), similar gas responses to 4 diffferent gases (5 ppm $C_2H_5OH$, CO, $H_2$, and trimethylamine), and very sluggish recovery speed (90% recovery time > 800 s). In contrast, 2 wt% Sb-doped $SnO_2$ showed the selective detection toward $C_2H_5OH$ and trimethylamine, relatively low resistance ($176k{\Omega}$) for facile measurement, and ultrafast recovery speed (90% recovery times: 6 - 18 s). The change of gas sensing charactersitics by Sb doping was discussed in relation to gas sensing mechanism.