• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.1919-1920
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• 2006

This paper deals with the design review of a power converter topologies for CEDMCS (Control Element Drive Mechanism Control System). The CEDMCS provides the control signals and motive power to operate the CEDMS. The CEDM's raise and lower the CEAs (Control Element Assemblies) in the reactor core. The CEAs are constructed with the Boron-10 isotope which has a high microscopic cross section of absorption for thermal neutrons. This characteristic causes the addition of negative reactivity when a CEA is inserted and positive reactivity when it is withdrawn from the reactor core.

• Journal of Advanced Marine Engineering and Technology
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• v.15 no.3
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• pp.31-38
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• 1991

Due to the structural complexity and the mutual interference of "water columns", the estimations of absorption power for a large wave energy conversion devices of flosting type in ocean could not achieve the desired results. Thus, in this paper the authors will propose a new methodology based on the three dimensional source ditribution method. We distributed the source to the device and the thin & light plate in "water column", And from the behaviour of this plated, the power and the pressure in water column are calculated. But, yet method should be proved to be valid by experiment.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.208-211
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• 2009

To reduce the peak demand the promotion of gas cooling(absorption chillers and GHPs) is required. In this study the effect of electric power peak-cut has been analyzed using two methods. One is based on monthly LNG consumption data and the other is using the gas cooling capacity installed. Both methods agreed well with each other within the uncertainty of 20%. It was found that the gas cooling had the peak cut effect of 1,500-2,000 MW for recent 5 years (2003 - 2007). The ratio of gas cooling to the whole cooling demand was 12-15%, which is needed to be increased.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.6
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• pp.647-653
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• 1988

A rapid thermal annealing system using tungsten halogen lamp has been designed and assembled. A control scheme where the temperature control is executed with calculated wafer temperature by considering the thermocouple delay rather than measured thermocouple temperature,is proposed. This control scheme gives more accurate control of the wafer temperature. In addition, the distribution of transmitted light power to the wafer in the system has been simulated, and lamp interval modification has been able to give more uniform light power distribution. Considering incident light spectrum, absorption, reflection, radiation of silicon, etc., temperature profile has been simulated. When the light power uniformity on the 3" wafer is below 1%, the temperature uniformity is about 2%.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.452-459
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• 1997

For computer aided design and construction of low noisy power plants, indoor and outdoor noise prediction program has been developed. The program utilizes the predefined data of noise sources and building materials and has the faculty to estimate the source level using the empirical formula in case of the measured data not being available. In the noise prediction, the mutual noise propagation between indoor and outdoor sites are considered. The outdoor noise source in the calculation of geometric divergence effects is modelled as the omni-directional finite line or planar source according to the source geometry and the receiving points. Outdoor noise prediction is carried out to consider the diffraction effect due to plant structures as well as the attenuation effect due to atmospheric absorption and soft ground. The results of indoor and outdoor noise prediction for a recently constructed diesel engine power plant show good agreement with the measured.

• Journal of Power System Engineering
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• v.17 no.5
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• pp.44-51
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• 2013

This paper proposes and analyzes recycling of optical phonons emitted by nonradiative decay, which is a major thermal management concern for high-power light emitting diodes (LED), by introducing an integrated, heterogeneous barrier cooling layer. The cooling is proportional to the number of phonons absorbed per electron overcoming the potential barrier, while the multi-phonon absorption rate is inversely proportional to this number. We address the theoretical treatment of photon-electron-phonon interaction/transport kinetics for optimal number of phonons (i.e., barrier height). We consider a GaN/InGaN LED with a metal/AlGaAs/GaAs/metal potential barrier and discuss the energy conversion rates. We find that significant amount of heat can be recycled by the barrier transition cooling layer.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.6
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• pp.538-541
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• 2016

This paper proposes an LCL-filter design for space vector pulse width modulation (SVM) in grid-connected three-phase inverter systems. Although there are a several studies in progress, the existing methods are erroneous because they do not focus on the other switching methods. This paper presents the design methodology for an LCL-filter that is optimized for SVM switching operations. The design procedure for the LCL-filter is presented step-by-step. The inverter-side inductor was determined by an analysis of the ripple components, mathematically. Based on the reactive power absorption ratio, the filter capacitor was determined. The grid-side inductor was determined by the ripple attenuation factor of the output current. Experimental results verify the validity of the design method for the LCL-filter.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.235-240
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• 2008

The recent development of efficient thermal prime movers for distributed generation id changing the focus of the production of electricity from large centralized power plants to local generation units scattered over the territory. The scientific communality is addressing the analysis and planning of the distributed energy resources(der) with wide spread approaches, taking into account technical, environmental, economical and social issues. The coupling of cogeneration system to absorption/electric chillers or heat pumps as well as the interactions with renewable sources, allow for setting up multi-generation systems for building cooling heating and power(BCHP) systems of different energy vectors such as electricity, heat(at different enthalpy levels), cooling power, hydrogen, various chemical substances and so forth. Adoption of the composite multi-generation systems may lead to significant benefits in term of higher efficiency, reduced $CO_2$ emissions and enhanced economy. This paper outlines the main aspects of the BCHP system framework, illistrating its characteristics and summarizing the relevant distributed multi-generation structures.

• Korean Journal of Optics and Photonics
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• v.12 no.6
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• pp.489-495
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• 2001

We developed a design code for a diode side-pumped Nd:YAG laser with a diffusive reflector to investigate the optimum design conditions resulting in homogeneous absorption distribution and efficient laser output power. By including the thermal tensing effect in the calculation of the laser output power, the calculated output powers were in fairly good agreement with the experimental results within the stable resonator condition. The calculation method can be used effectively for a diode side-pumped Nd:YAG laser in choosing the optimum design parameters and in predicting the laser output power.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.220-220
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• 2013

Surface-normal transmission electro-absorption modulator (EAM) are attractive for high-definition (HD) three-dimensional (3D) imaging application due to its features such as small system volume and simple epitaxial structure [1,2]. However, EAM in order to be used for HD 3D imaging system requires uniform modulation performance over large area. To achieve highly uniform modulation performance of EAM at the operating wavelength of 850 nm, it is extremely important to remove the GaAs substrate over large area since GaAs material has high absorption coefficient below 870 nm which corresponds to band-edge energy of GaAs (1.424 eV). In this study, we propose and experimentally demonstrate a transmission EAM in which highly selective backside etching methods which include lapping, dry etching and wet etching is carried out to remove the GaAs substrate for achieving highly uniform modulation performance. First, lapping process on GaAs substrate was carried out for different lapping speeds (5 rpm, 7 rpm, 10 rpm) and the thickness was measured over different areas of surface. For a lapping speed of 5 rpm, a highly uniform surface over a large area ($2{\times}1\;mm^2$) was obtained. Second, optimization of inductive coupled plasma-reactive ion etching (ICP-RIE) was carried out to achieve anisotropy and high etch rate. The dry etching carried out using a gas mixture of SiCl4 and Ar, each having a flow rate of 10 sccm and 40 sccm, respectively with an RF power of 50 W, ICP power of 400 W and chamber pressure of 2 mTorr was the optimum etching condition. Last, the rest of GaAs substrate was successfully removed by highly selective backside wet etching with pH adjusted solution of citric acid and hydrogen peroxide. Citric acid/hydrogen peroxide etching solution having a volume ratio of 5:1 was the best etching condition which provides not only high selectivity of 235:1 between GaAs and AlAs but also good etching profile [3]. The fabricated transmission EAM array have an amplitude modulation of more than 50% at the bias voltage of -9 V and maintains high uniformity of >90% over large area ($2{\times}1\;mm^2$). These results show that the fabricated transmission EAM with substrate removed is an excellent candidate to be used as an optical shutter for HD 3D imaging application.