• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1751-1754
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• 2003

CCD Camera System으로 capture 한 image를 표준 display장치로 재현할 때 capture 할 당시의 원 피사체의 모습을 그대로 재현하여야만 한다. 그러나 일반 consumer 용 camera system의 CCD channel spectral sensitivity 특성이 인간의 spectral sensitivity(1(λ), m(λ), 5(λ)) 특성과 일치하지 않고, linear transform의 관계도 성립하지 않음으로써 capturing시 근본적인 color error가 발생하게 된다. 기존의 CCD Camera System 에서는 CCD sensor 의 color 정보와 display 장치의 color 정보와의 단순한 산술적인 관계로 color를 재구성하는 방법을 사용하고 있어 원 피사체의 color 를 그대로 재현할 수가 없다. 본 논문에서 제시하는 알고리즘은 CCD 의 channel spectral sensitivity특성 과 CIE-color matching function과의 관계를 고려하여 color를 재구성함으로써 color error를 줄이도록 하였다 제시된 알고리즘의 color error를 검증하기 위하여 물체의 고유반사율을 알고 있는 AGFA IT8.7-2 test chart(283 spectra), Dupont Paint Chips(120 spectra), Mcbeth Color Checker(64 spectra) 및 Natural Objects(170 spectra) 등 다양한 objects spectra(637 spectra) [1][2]를 이용하여 기존 방법의 알고리즘과 비교하여 보았다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.244-245
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• 2005

This paper presents the performance of BALUN embedded in the LTCC substrate of ZigBee system which is one of the kind of wireless communication. The BALUN is used to make two signal which have 180$^{\circ}$ phase difference and 3dB power from one input signal. Therefore, this is 3-port network circuit. At the center frequency(915MHz), insertion losses were 3.1dB and 3.4dB, respectively. Also, the phase difference was 182$^{\circ}$. Its size is 2.1$\times$3.6mm. The Used materials were dupont9599 LTCC ceramic and daejuo086 Ag.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.163-166
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• 2005

Multilayer LTCC technology enables RF modules to be reduced dramatically by taking advantage of the three dimension flexibility. Compared to a conventional two dimensional PCB, LTCC allows higher density, reduced size, and lower cost. In this research, BPF based on LTCC for 900MHz ZigBee application was implemented which can replace SAW filter with using the material of the Dupont9599's dielectric constant 7.8. And distributed baud pass filter for 900MHz ZigBee system applications is presented. Using resonator stripline and capacitance, 2nd order band pass filter was designed. Adjusting resonator's length and capacitance is easy to tune at accurate center frequency by shifting band because ZigBee system is using narrow bandwidth, $902MHz^{\sim}928MHz$. Also resonator has no limitation in space, so reducing size is possibile. Designed filter had I.L. 2.8dB at 915MHz and attenuation at 815MHz, 1015MHz was 16dB, 15dB, respectively. Therefore, the sharpe cut-off and good insertion loss for ZigBee system application.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.1
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• pp.86-98
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• 2014

This study examined a long-standing issue with its perverse results in the Korean capital markets, such as any variant financial profiles over time, affecting capital structure for the firms belonging to the chaebols. It may be of interest to identify these components from the perspectives of international investors and domestic policy makers to implement their contingent strategies on the target leverage, since the U.S. financial turmoils in the late 2000s. Regarding the evidence from the three hypothesis tests on the firms in the chaebols, this research found that the control variabels measuring profitability, business risk, and non-debt tax shields, showed their statistically significant relationships with the different types of a debt ratio. While FCFF(free cash flow to the firm) showed its significant influence to discriminate between the firms in the chaebols and their counterparts, not belonging to the chaebols, BDRELY as the ratio of liabilities to total assets, comprising the enhanced 'Dupont' system, only showed its statistically significant effect on leverage in the context of the parametric and nonparametric tests. In line with the results obtained from the present research, one may expect that a firm in the Korean chaebol, may control or restructure its present level of capital structure to revert to its target optimal capital structure towards maximizing the shareholders' wealth.

• The Journal of the Korea Contents Association
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• v.14 no.6
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• pp.367-384
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• 2014

This study addresses an empirical issue which has been received little attention in the contemporary finance literature: To identify any financial determinants of the profitability indices for the firms belonging to the Korean chaebol. Three hypotheses of concern were postulated and tested for the sample firms covering the periods of the pre-and post-financial global crises. Regarding the results on the 1st hypothesis test of characterizing any financial profiles for the firms (belonging to the chaebols) by estimating a legitimate panel data model: the present study found the statistically significant relationships of the explanatory variables (BVLEVl, MVLEVl, MV/BV, RISK, FCFF and FOS) with the book-value based profitability ratio: while the market-valued profitability index was explained only by BVLEV2. Regarding the 2nd hypothesis test for the profitability of the sample firms at the industry level: the chaebol firms in the chemical and the food industries overall positioned themselves into the top ranks in order, which was tested by the ANCOVA and the Tukey multiple comparison procedure. Finally: on the 3rd hypothesis test for the 'adjusted' Dupont system, only two such as the 'operating margin' and the 'asset turnover' showed their significant effects between the chaebol firms and their counterparts in both the (parametric) independent samples t-test and the (nonparametric) Wilcoxon-Mann-Whitney statistics.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5476-5487
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• 2013

From foreign and/or domestic investors' perspectives, it may be interesting to find any financial attributes or profile of the firms headquartered in 'Chungcheong' province concerning profitability, given that this subject so far drew less attention in the previous literature. This study performed three hypothesis tests on the profitability indicator by utilizing the models such as the 'panel data' one and the 'logistic' regression one, applying a modified 'Dupont' system. With respect to the major findings, the results identified that the proxies measuring leverage across the book-value(BVLEV1) and the market-value(MVLEV1) bases, were statistically significant constituents determining profitability. Another explanatory variable, SIZE, with its positive and statistically significant relationship to the indicator, represented that the firms in the province were smaller than their counterparts in the other regional areas in Korea. DRELY applying a modified 'Dupont' system, found to be the only statistically significant discriminating factor between these comparison groups. As one of the primary contributions of this study, the outcomes may be used by the financial institutions operated across the regions including Seoul Metropolitan area, when implementing their lending practices to provide funds for potential borrowers such as the firms belonging to 'Chungcheong' province.

• Journal of the Korean Solar Energy Society
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• v.38 no.6
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• pp.51-63
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• 2018

Nowadays the bifacial PV system market and its applications are increasing rapidly. The performance of the bifacial PV system take advantage of its rear surface irradiance. Also, the ground albedo, PV module tilt and azimuth, PV module installation height, shading effect and module temperature are factors of bifacial PV system performance. This paper investigates how the performance of bifacial PV system is influenced by above factors. First, we analyzed the energy yield depending on PV module installation by simulation. Secondly, we compare energy performance evaluation of monofacial and bifacial module on different weather condition by experiment. Thirdly, we tested the albedo effect and checked operating characteristics using Dupont Tyvek material for the bifacial PV module. Fourthly, we check the shading effect of bifacial PV module on bypass diode operating. Finally, we applied the bifacial PV module in the nearby subway station for the noise reduction barrier using a qualified simulation program. In summary, we confirm that the energy performance superiority of the bifacial PV module has a lot of application use including road. Also, we have confirmed the bifacial module and inverter design should be considered by rear surface irradiance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.10a
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• pp.65-70
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• 1996

엔진소음을 소음특성에 따라 분류하면 공력소음(Aerodynamic Noise), 연소소음(Combustion Noise), 기계적인 소음(Mechanical Noise)으로 나눌 수 있으며 소음원의 종류에 따라 분류하면 배기계소음(Exhaust System Noise)으로 나눌 수 있으며 소음원의 종류에 따라 분류하면 배기계소음(Exhaust System Noise), 흡기계소음(Intake System Noise), 냉각계소음(Cooling System Noise), 엔진표면소음(Engine System Noise)등으로 분류할 수 있다. 이러한 여러소음중 엔진 내부의 유동에 의한 흡배기계통으로의 소음방출은 자동차 실 내외 소음의 중요한 문제로 대두되는데, 이를 줄이기 위해 그 동안 소음기 등의 서브시스템의 형태와 그 위치조정에 관한 연구가 수행되어 왔다. 그러나 이것이 비용 또는 성능에 영향을 미치므로 본질적인 소음원을 규명해 내는 것이 필요하게 되었다. 흡배기계의 소음은 엔진의 흡입, 배기행 정시 피스톤의 운동에 의해 팽창 및 압축파 형태의 압력파(pressure wave)로 발생하게 되고, 밸브근방에서는 유동의 박리(separation)에 의해 발생하게 된다. 소음기 등의 서브시스템에서도 유동의 박리에 의해 발생하게 되며 특히 배기행정시 발생하는 압력파는 비선형영역에 있게된다. 흡기소음은 배기에 비해 그 크기가 작아서 그동안 등한시 되어왔으나 이것이 소비자의 불평요인으로 작용하므로써 이에 대한 연구도 활발히 수행되어야 한다. Bender, Bramer[1]는 흡배기계 소음의 외부 방사에 관하여 전반적으로 기술하였고 Sierens등[2]은 흡기계에서 1차원 MOC(Method of Characteristics)방법으로 비정상 유동해석을 하고 실험결과와 비교하였다. J.S.Lamancusa 등[3]은 흡기 소음원을 실험을 통해 예측하였고, 흡기소음도 비선형 거동을 보인다고 밝혔다. Yositaka Nishio 등[4]은 새로운 흡기실험장치를 고안하여 공명기(resonator)의 위치 변화에 의한 저소음 흡기계를 설계 초기단계에서부터 적용하려 하였다. 일반적으로 흡배기계의 복잡한 형상 때문에 대부분 실험을 통해 문제를 해결하려 하였고, 수치해석은 피스톤의 운동을 배제한 단순화한 흡배기계의 정상상태 유동해석이 주를 이루어왔다. Taghaui and Dupont 등[5]은 KIVA코드를 사용하여 흡기포트와 연소실 그리고 밸브의 움직임을 동시에 고려한 수치해석을 도입하였다. 하지만 이들이 밸브의 운동을 고려하기 위해 사용한 이동격자는 격자점은 시간에 따라 변화하지만 그 격자의 수가 일정하게 유지되어 있어서 밸브의 완전개폐를 해석할 수가 없다. 강희정[6]은 단일 실린더와 단일 배기밸브를 갖는 문제로 단순화하여 피스톤과 밸브의 움직임을 고려하므로써 배기행정 후 소음이 어떻게 전파해 나가는가를 연구하였다. 본 연구에서도 최소밸브간격과 최대밸브간격 사이에서만 계산이 가능하나 흡기의 경우는 밸브가 닫힐 때 생기는 압력파가 중요하므로 실린더와 밸브사이에 벽면조건을 주어 밸브의 개폐를 모사하였다.