• Proceedings of the KSR Conference
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• 2009.05b
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• pp.527-532
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• 2009

Recently, Interior Permanent Magnet Machine(IPM) is widely used for traction motor in the high speed train. Due to the high efficiency and high power density of the IPM, it has lots of heat sources such as iron loss and copper loss. These heat sources can cause the demagnetization of permanent magnet, losses in output power and even irreversible defect of the IPM. To prevent the power loss caused by heat sources, the accurate thermal analysis has to be carried out. For the thermal analysis of the IPM, the thermal network is designed for this traction motor. The thermal analysis has executed at rated speed operation. The result of thermal network analysis can be used for the IPM design process.

• Journal of the Korean Society for Railway
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• v.11 no.4
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• pp.410-416
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• 2008

The inter-industrial inducement effects of the korean railway services on the output, value-added, imports of the 403 industrial sectors of the korean economy have been computed by the input-output analysis technique utilizing the 2003 Input-Output Tables, which was published most recently in April 2007 by the Bank of Korea. The korean railway service industry produced \2,766 billion worth of passenger and freight railroad services in the 2003 year, and it has induced \1,701 billion worth of output, \781 billion worth of value-added, and \580 billion worth of imports of the korean industry as a whole. The energy sector industries such as diesel fuel, thermal power generation, nuclear power generation, crude oil, liquid natural gas, bituminous coal, liquid propane gas have been most affected by the korean railway services. Other industries mainly affected by the korean railway services include railroad car manufacturing, cleaning and decontamination, medical and health service, machinery equipment and rental, construction and maintenance, transportation related services, business R&D, property insurance, and telecommunication.

• Journal of the Korean Solar Energy Society
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• v.27 no.3
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• pp.23-28
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• 2007

In this study, we analyzed the maximum output power characteristics of crystalline silicon photovoltaic module by change of environmental effects. The electrical, optical and thermal property of PV modules were investigated during outdoor test period about 70 days. There was a fluctuation in maximum output power by change in transmittance caused by environment effects like rain, snow and dust. The effects of external environmental change were analyzed using climate data. Also local thermal temperature variation and transmittance imbalance on surface of PV module which might lead degradation of constituent material were detected using infrared camera. The further analysis is describe in the following paper.

• Nuclear Engineering and Technology
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• v.35 no.5
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• pp.399-411
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• 2003

A model predictive control method is applied to design an automatic controller for thermal power control in a reactor core. The basic concept of the model predictive control is to solve an optimization problem for a finite future at current time and to implement as the current control input only the first optimal control input among the solutions of the finite time steps. At the next time step, the second optimal control input is not implemented and the procedure to solve the optimization problem is then repeated. The objectives of the proposed model predictive controller are to minimize the difference between the output and the desired output and the variation of the control rod position. The nonlinear PWR plant model (a nonlinear point kinetics equation with six delayed neutron groups and the lumped thermal-hydraulic balance equations) is used to verify the proposed controller of reactor power. And a controller design model used for designing the model predictive controller is obtained by applying a parameter estimation algorithm at an initial stage. From results of numerical simulation to check the controllability of the proposed controller at the $5\%/min$ ramp increase or decrease of a desired load and its $10\%$ step increase or decrease which are design requirements, the performances of this controller are proved to be excellent.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.8
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• pp.51-59
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• 2013

High temperature fuel cell system, such as molten carbonate fuel cells(MCFC) and solid oxide fuel cells(SOFC), are capable of operating at MW rated power output. The power output change of high temperature fuel cell imposes the thermal and mechanical stresses on the fuel cell stack. To minimize the thermal-mechanical stresses on the stack, increases in the power output of high temperature fuel cell typically must be made at a slow rate. So, the short time interruption of high temperature fuel cell causes considerable generated energy losses. Because of the characteristic of high temperature fuel cell, we analyzed the impact of electrical fault in the fuel cell plant on other fuel cell generators in the same plant site. A various grounding configuration and voltage sag are analyzed. Finally, we presented the solution to minimize the effect of fault on other fuel cell generators.

• Korean Journal of Optics and Photonics
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• v.17 no.2
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• pp.198-202
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• 2006

Resonator stability condition, $M^2$ beam quality factor, and laser output power are analyzed for two types of two-rod Nd:YAC lasers with rod-end curvatures. Two laser rods with rod-end curvatures are positioned closely to each other or placed separately near each resonator mirror. Experimentally, the output powers and $M^2$ beam quality factors of those lasers are measured with and without thermal birefringence compensation, and compared to numerical analyses.

• Journal of Energy Engineering
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• v.12 no.3
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• pp.190-196
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• 2003

A study of the performance effect of Indolene-Methanol Plus High Alcolhols (MPHA) has been completed. The study invested the measurement of performance parameters. The performance parameters measured are minimum advance for best torque (MBT) spark timing, power output and thermal efficiency. The alcohol concentration was varied from 0 to 100 percent by volume in clear Indolene. The performance parameters were measured using a single cylinder spark ignition engine at different compression ratios. The results of the performance measurements indicated that Indolene-MPHA blends have a higher MBT spark advance, similar power output and lower thermal efficiencies than Indolene-Methanol blends.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.22.2-22.2
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• 2011

Reliability and degradation mechanism of conventional phosphor-converted white GaN-based light-emitting diodes (LEDs) were investigated. Under electro-thermal stress condition, the optical output degraded rapidly at the initial stress time accompanied by the change of chromatic properties. This could be attributed to the optical degradation of packaged materials, in particular, the browning of encapsulants and the darkening of reflective packages. At longer stress times, the optical output gradually decreased according to the degree of the reverse leakage currents, namely, the generation ofnonradiative recombination defects. This indicates that the optical degradation of white LEDs are dominated by the darkening of packaged materials and the generation of defects depending on the injection current and ambient temperatures. Using analyses of electroluminescence spectra, optical microscopy, electrical, optical, and thermal properties, optical degradations of white LEDs are discussed.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.265-271
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• 2003

This study is for the stable optical source in order to get the precision measurement, which contributes to help the laser frequency and the output to be settled. The laser optical frequency is changed by the length of resonance cavity. The length variation of the laser resonance amplitude is affected by the thermal expansion of that system. So, we try not only to adjust the temperature of the laser tube using the heater for fine length of resonance cavity, but also to maintain the fixed temperature of the resonance cavity for outputting the safe laser optical frequency. Therefore, we must take materials with the thermal expansion of the supporting system, which is closer to it of the laser resonance cavity. Using the materials, we can promote to stabilize the temperature of it. In advance, we also plan to get the settlement of the laser frequency and the output in the long km, optimizing and stabilizing the system.

• The KSFM Journal of Fluid Machinery
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• v.19 no.2
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• pp.43-48
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• 2016

This study proves successes of Energy Service Company (ESCO) business by heat pump performance test. The purpose of ESCO business is recover investment costs through saving energy from installation of energy reduction facility. The most important technology assessment items are heat recovery and generator output. Experimental result shows that increase quality of heat recovery (11.52Gcal/h), while decrease generator output (0.234kw). In its final analysis, the ESCO business is successful according to our data.