• Korean Journal of Environmental Biology
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• v.25 no.2
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• pp.124-138
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• 2007

In order to characterize the current status and distribution of reptiles currently inhabiting the Republic of Korea, the results of survey data were analyzed in this study. The results of this analysis showed that the reptiles were distributed into two orders, seven families, and 21 species, with the exception of six marine reptiles, including Dermochelys coriacea schlegelii, Chelonia mydas japonica, Caretta caretta, Hydrophis melanocephalus, Hydrophis cyanocinctus, and Pelamis platrrus. Also, the taxonomic revisions of several species were suggested, although this would be ill-advised before further studies can be conducted regarding the current status of marine reptiles in the region.

• Journal of Power Electronics
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• v.15 no.4
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• pp.964-973
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• 2015

This paper presents a simple approach for the selective harmonic elimination (SHE) of multilevel inverter based on the transistor-clamped H-bridge (TCHB) family. The SHE modulation is derived from the sinusoidal voltage-angle equal criteria corresponding to the optimized switching angles. The switching angles are computed offline by solving transcendental non-linear equations characterizing the harmonic contents using the Newton-Raphson method to produce an optimum stepped output. Simulation and experimental tests are conducted for verification of the analytical solutions. An Altera DE2 field-programmable gate array (FPGA) board is used as the digital controller device in order to verify the proposed SHE modulation in real-time applications. An analysis of the voltage total harmonic distortion (THD) has been obtained for multiple output voltage cases. In terms of the THD, the results showed that the higher the number of output levels, the lower the THD due to an increase number of harmonic orders being eliminated.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.385-387
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• 1994

Optical interconnections are more attractive than electronic interconnections because of their higher speed, freedom from planar constraints, immunity to electromagnetic interference effects and higher interconnection capacity. Volume hologram is one of the best way to implement optical interconnections. Diffraction efficiency and crosstalk effect are very important things for ensuring independent interconnections. Recently, a general systematic method that can handle a large number of superposed volume gratings in anisotropic host material is presented. In this study for numerical analysis of diffraction, above method is programmed in general form near Bragg angle. Diffraction orders for variation of grating strength are determined by comparing with the coupled-mode method. The effects of parameter variation are considered. Parameters include vertical and azimuthal incident angle, wavelength and interaction length. Diffraction analyses are also performed for intra-mode and inter-mode diffractions.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.167-170
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• 2009

Currently, unlike domestic market It is trend that world construction market scale is increasing continuously but Experts who need in International Construction Market are insufficient absolutely. Despite the amount of orders received continuously increased, Experts who needed for overseas construction market are lacking. And we need to examine that Experts who needed for overseas construction market an supplied to the country. It is time to make decision how can we supply them to the country. Consequently, this project will study Educational programs of the past for Training International Construction Experts, provide the solutions breeding International Construction Experts.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.42-45
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• 1995

This paper describes the flux density in air gap, harmonic torques occurring by inadequate slot combination of induction motor using the fourier series. The analysis uses DFT(Discrete Fourier transform) to analyze harmonic orders of flux density. It is certified that the harmonic flux density has the same result using Fourier series and FEM.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1553-1562
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• 2017

For the purpose of enhancing the performance of the shunt active power filter (APF), this paper presents a novel Fast Weighted Compound Control (FWCC) strategy based on the synchronous frame. In this control strategy, the proposed new repetitive controller can work faster and more stably by reducing the internal model cycle and introducing a damping coefficient. In addition, the harmonic detector can be removed to simplify the structure of the APF owing to the improvements. Furthermore, a proportional-integral (PI) controller is added to work in parallel with the repetitive controller by using a weighted ratio. Then, a convergence speed analysis and design algorithm are given in detail. Simulation and experimental results show that the harmonic distortion is reduced from 2.91% to 1.89%. In addition, the content for each of the characteristic harmonic orders has decreased by more than three times.

• Journal of Aerospace System Engineering
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• v.15 no.6
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• pp.26-32
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• 2021

The global aircraft-manufacturing industry ecosystem is characterized by the international division of labor through the worldwide supply chain and by the concentration of value added at the top of the supply chain. As a result, the competition for entry into the top supply chain and for order expansion is becoming increasingly intensive. To increase their orders, domestic aircraft manufacturing enterprises need to enhance their competitiveness by evaluating and analyzing it. However, most domestic aircraft manufacturing companies are unaware of the need to quantitatively evaluate their competitiveness. It is challenging to perform such an evaluation, and there are few research cases. In this study, we quantitatively evaluated and analyzed the competitiveness of domestic aircraft manufacturers by using data mining techniques. Thereby, implications for enhancing their competitiveness could be identified.

• ETRI Journal
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• v.44 no.3
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• pp.504-511
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• 2022

Monte Carlo simulations show that, as temperature increases, the average kinetic energy of channel electrons in a GaN transistor first decreases and then increases. According to the calculations, the relative energy change reaches 40%. This change leads to a reduced barrier height due to quantum coupling among the three-dimensional motions of channel electrons. Thus, an analysis and physical model of the gate leakage current that includes drift velocity is proposed. Numerical calculations show that the negative and positive temperature dependence of gate leakage currents decreases across the barrier as the field increases. They also demonstrate that source-drain voltage can have an effect of 1 to 2 orders of magnitude on the gate leakage current. The proposed model agrees well with the experimental results.

• Journal of Species Research
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• v.10 no.2
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• pp.134-141
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• 2021

During a survey of indigenous prokaryotic species diversity of the upstream Nakdong River, South Korea, 12 bacterial strains were isolated for further analysis. These bacterial strains were identified showing at least 98.7% 16S rRNA gene sequence similarity with known bacterial species that were previously unreported in South Korea. The 12 bacterial strains were phylogenetically diverse and assigned to four classes, eight orders, nine families, and ten different genera. The isolates were identified as Leucobacter holotrichiae (99.1%), Leucobacter tardus (99.9%), Rhodococcus rhodochrous (99.9%), Tessaracoccus oleiagri (100%), and Paeniglutamicibacter cryotolerans (99.3%), of the class Actinobacteria; Bacillus coagulans (99.7%) and Bacillus wudalianchiensis (99.1%) of the class Bacilli; Ochrobactrum pseudogrignonense (99.2%) and Paracoccus thiocyanatus (100%) of the class Alphaproteobacteria; and Ideonella azotifigens (99.0%), Polaromonas glacialis(99.3%), and Herbaspirillum seropedicae (99.5%) of the class Betaproteobacteria. The cellular and colonial morphology, biochemical properties, and phylogenetic position of these isolates were examined, and species descriptions are provided.

• International conference on construction engineering and project management
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• 2007.03a
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• pp.249-258
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• 2007

Recently orders of projects in the field of oil and gas plants have increased due to rising oil prices and consumption. The markets of oil and gas plants are expanding into the Middle East area and all over the world. Because the oil and gas markets have a lot of overseas construction operations, competition among advanced companies is more important. However, companies in the period of growth have not had enough competitive powers of license in the design phase. Therefore, they are faced with difficulty of adopting the technology which is maximizing the effect of investments, and scheduling of a long-range plan. In order to achieve adequate technology management and competitive power, this study considers a long-range plan through an analysis of an appropriate introduction and the strategic planning process of technology management.