• Journal of the Economic Geographical Society of Korea
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• v.22 no.4
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• pp.576-591
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• 2019

This study attempts to analyze the effects of distance-accessibility to the complex shopping mall of 'Lotte Mall-Suwon', located at the old central and catchment district of the Suwon station in the Province of Gyeonngi, on the prices of its neighboring apartments within the Gwonseon-gu of Suwon City by using the hierarchical and linear-difference in difference regression method. The results of the analysis are as follows. First, before construction the effects of distance-accessibility show the U-shaped pattern, suggesting that the negative external effects of noise and traffic congestion around the Suwon Station affected the prices of its neighboring apartments within the Gwonseon-gu of Suwon City. Second, the effects of distance-accessibility at different times, such as the construction period and after the opening, are statistically significant only in the latter, indicating the reverse U-shaped pattern unlike before the opening. This means that after the opening of the complex shopping mall its external effects as a leisure and convenience space have a positive effect on the prices of its neighboring apartments within the Gwonseon-gu of Suwon City. Third, the effects of distance-accessibility is at an inflection point around 1.6-1.7 kilometers, which means that the U-shaped distance-decay pattern before construction, while the reverse U-shaped pattern is shown after the opening of opening. The latter implies that apartments that are very close to the mall within the Gwonseon-gu of Suwon City enjoy relatively small positive externalities. Therefore, they are exposed to some negative external effects of noise and traffic congestion, but apartments with some distance apart within the Gwonseon-gu of Suwon City maximize those positive externalities. These results suggest that the effects to distance-accessibility are different from location to location.

• International Area Studies Review
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• v.13 no.3
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• pp.527-549
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• 2009

This paper investigates the relation of invert U-shape between the M/B ratio and leverage ratio by market, firm size, and a level of technology of firm. Our sample consists of 510 manufacturing firms continually listed on the Korea Securities Market and Kosdaq Market from January 1, 2001 to December 31, 2008. The total sample consists of the Korea Securities Market(large firms, high technology industry) sample of 2,248(1,816, 1,704) observations and the Kosdaq Market(small and medium firms, high technology industry) sample of 1,632(2,264, 2,376) observations. The empirical results show that the relation of invert U shape appears on the sample of the Kosdaq Market, small and medium firms, and high technology industry. However, the relation doesn't appear on the sample of the Korea Securities Market, large firms, and low technology industry. These mutually different results may be caused by the relatively low M/B ratio of the latter.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.839-840
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• 2015

IPM(Interior Permanent Magnet) 모터는 마그네틱 토크와 릴럭턴스 토크를 이용하는 모터이다. 이런 IPM 모터에 쓰이는 영구 자석 중 희토류 자석은 온도에 취약한 특성이 있어 낮은 온도에 비해 높은 온도에서 더 쉽게 불가역감자가 발생할 수 있다. 또한 페라이트자석에 비해 상대적으로 가격이 비싸 희토류 저감 IPM 모터 개발이 지속적으로 진행되고 있다. 따라서 본 논문에서는 희토류 저감 IPM 동기모터의 영구자석 위치를 변화한 3가지 U자형 2층 IPM 모터 모델을 선정하여 회전자 전류의 크기 및 위상 그리고 약자속 제어를 고려한 불가역 감자 특성을 비교 및 분석하였다. 이렇게 분석한 결과를 바탕으로 IPM 설계 시 불가역감자에 강인한 설계 방법에 대하여 고찰하였다.

• Environmental and Resource Economics Review
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• v.23 no.4
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• pp.667-688
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• 2014

This research tested the EKC (Environment Kuznets Curve) Hypothesis using the $CO_2$ Emissions by region and GRDP. We built the panel data set on the 15 local government region from 1990 to 2010 for this analysis. GRDP, population and total factor productivity was considered as the factors influencing on the regional $CO_2$ Emissions. Analysis method in this research is panel GLS model as Lantz and Feng (2006). The results show that the EKC hypothesis did not hold in Korea but there is inverted U relationship between the $CO_2$ Emissions and total factor productivity. As the total factor productivity grows, the $CO_2$ increased but decreased after a certain level.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.8
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• pp.745-753
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• 2011

In this paper, the planar monopole antenna for multi-band service is proposed. The proposed antenna, which is a rectangular patch antenna with a U-shaped slit based on a monopole antenna for wide bandwidth characteristic, is designed and analyzed. The antenna size has been miniaturized by using the U-shaped slit. The frequency characteristics are modified and optimized by varying specific parameters. To obtain desired frequency bands, the U-shaped slit and patch lines have been applied. Whole antenna dimensions including the ground plane are $35{\times}50{\times}1\;mm^3$, and the antenna part size is $35{\times}27\;mm^2$. It is fabricated on the FR-4 substrate(${\epsilon}_r=4.4$) using a microstrip line of $50{\Omega}$ for impedance matching. For the measured results, the impedance bandwidth below a VSWR of 2 is 790~916 MHz, 1.74~2.14 GHz, and 2.36~3.13 GHz. The fabricated antenna is satisfied with the aimed impedance bandwidth in GSM/DCS/US-PCS/UMTS/Bluetooth/S-DMB applications.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.19 no.1
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• pp.51-56
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• 1983

In the stability problem of the U-grooved plate, it has a circular hole, the site of the hole determines some different deformation mode when it was loaded. To determine the optimal position of the circular hole-center which not to get large distortion of the hole itself, in this paper, we studied the distributions of stresses in the neck area between hole and U-groove and the distortion mode of the deformed hole by B.E.M(Boundary Element Method) and compared with experimental results in four cases. For a distributed load, according to the center of the hole moves closer to the U-groove center (c.-c. line), the shape of the circular hole was transformed to the elliptical one(it's major axis perpendicular to the c.-c. line). In this problem, the results by Boundary Element Method was well accorded with Experiments.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.5
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• pp.33-39
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• 2021

In this study, we tried to find the correlation of the parameters and dual resonance of U-slot microstrip patch antenna with L-shaped Inset-feed structure and design broadband antenna using them. In the first step, we classified cases where dual resonance occurs through changes in antenna parameters that affect antenna performance. In the second step, we correlated each antenna parameter to the location and intensity of the resonance point, and 3 dB bandwidth. Next, antenna simulation confirmed the process of designing to have wide bandwidth using the correlation in the second step previously presented in the U-slot antenna case with narrow bandwidth. Finally, we fabricated a designed antenna and demonstrated the validity of antenna bandwidth broadening through the correlation analysis.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.8 s.99
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• pp.803-809
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• 2005

This paper presents a novel method of mutual coupling suppression between antenna elements for performance improvement in planar array antenna system. Two miniature patch antenna elements satisfied IEEE 802.1 la($5.75\~5.35\;GHz,\;5.75\~5.85\;GHz$) are used for this research, they are arrayed by half wave length interval. It is observed about -20 dB mutual coupling between each antenna element at center frequency. To suppress mutual coupling, the arrayed antennas with a reversed 'U' structure are observed below -30 dB mutual coupling at IEEE 802.1la band.

• Journal of Korea Technology Innovation Society
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• v.21 no.1
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• pp.454-490
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• 2018

This paper examined the nonlinear relationships between external knowledge sources and the innovation performance of SMEs (small and medium-sized enterprises). Using 3,218 firm-year panel data in South Korea, this study found that increasing the number of external knowledge channels out of the value chain increases radical innovation. Meanwhile, increasing the number of external knowledge channels within the value chain increases the incremental innovation. Further, the external sources of knowledge both out of and in the value chain had inverted U-shaped relationships on radical and incremental innovation respectively. This finding implies that a mechanism of diminishing returns works in the relationship between the external sources of knowledge and innovation. The study also identified the synergistic effects between the external sources of knowledge out of the value chain and within the value chain, and confirmed that the synergistic effects strengthen the linear mechanism between the external sources of knowledge and innovation. In addition, this study found that the sources of knowledge both out of and within the value chain positively moderate the relationships between R&D investment and radical innovation of SMEs.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.9
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• pp.60-66
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• 2008

In this paper, the CPW-fed Ultra-wideband antenna is designed and fabricated for UWB communications. To achieve ultra-wide bandwidth of the antenna, we propose the mutual coupling of two planar monopole antennas. The mutual coupling of monopole pair of the proposed antenna is optimized by adjusting the parameters, the widths of the planar monopoles and the space between two monopoles. Two UWB antennas with different horizontal sections of the CPW-fed monopole antenna are fabricated and measured to examine the mutual coupling effects on the monopole pair antenna. The measured result show that two antennas are satisfied with UWB communication band(3.1$\sim$10.6Ghz).