• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.577-580
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• 2002

본 논문에서는 $\Sigma\Delta$ 변조된 입력신호를 갖는 적응필터의 수렴특성 및 연산량을 향상시키는 방안을 제시하였다. 하드웨어측면에서 효율적인 해상도를 내는 $\Sigma\Delta$ 변조기는 중저파 대역의 신호를 처리하는데 널리 사용되고 있다. $\Sigma\Delta$ 변조신호는 항상 $\pm$1의 값만을 갖기 때문에, 사인알고리즘을 사용하는 적용필터와 효율적으로 결합될 수 있다. 하지만 PCM 신호에 비하여 $\Sigma\Delta$ 변조신호의 상대적인 길이가 길어 이를 처리하는 적응필터의 길이가 증가하고 이에 따른 연산량도 증가하고, 아울러 사인 알고리즘 자체가 갖는 수렴속도의 문제점 때문에 이러한 결합은 불안정한 수렴 특성을 보이게 된다. 본 연구에서는 $\Sigma\Delta$ 변조된 입력신호에 대하여 웨이블릿 변환을 적용한 변환영역 적응필터를 설계하였으며, 필터계수의 일부분만을 주기적으로 갱신함으로써 연산량을 줄이는 방안과 수렴속도의 향상됨을 시스템 식별의 응용 예를 통하여 검증하였다.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2586-2588
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• 2002

본 논문에서는 $\Sigma\Delta$ 변조된 입력신호를 갖는 적응필터의 수렴특성을 연구하여 향상 방안을 제시하였다. 하드웨어적인 측면에서 효율적인 해상도를 내는 $\Sigma\Delta$ 변조기는 중저주파 대역의 신호를 처리하는데 널리 사용되고 있다. $\Sigma\Delta$ 변조신호는 항상 $\pm1$의 값만을 갖기 때문에, 사인 알고리즘을 사용하는 적응필터와 효율적으로 결합될 수 있다. 하지만, PCM 신호에 대비하여 $\Sigma\Delta$ 변조 신호의 상대적인 길이가 길어 이를 처리하는 적응필터의 길이가 증가하고, 아울러 사인 알고리즘 자체가 갖는 수렴속도의 문제점 때문에 이러한 결합은 불안정한 수렴 특성을 보이게 된다. 본 연구에서는 $\Sigma\Delta$ 변조된 입력신호에 대하여 웨이블릿 변환을 적용한 변환영역 적응필터를 설계하였으며, 수렴속도가 향상됨을 시스템 식별의 응용예를 통하여 검증하였다.

• Environmental and Resource Economics Review
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• v.28 no.1
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• pp.1-37
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• 2019

This study investigates the convergence in per capita $CO_2$ emission by income group for an unbalanced panel of 152 countries from 1980 to 2013 using beta and sigma convergence model. Absolute beta and sigma convergence differed by $CO_2$ emission reduction policies in each countries. Conditional beta convergence shows that per capita income has a negative effect on growth in per capita $CO_2$ emission. In particular, better-quality institutions and technology accelerated the negative effect of per capita income on the speed of convergence of per capita $CO_2$ emission in high-income countries. For middle-income countries, the growth of income affected the convergence of $CO_2$ emission per capita, but institutional quality has an insignificant impact. On the other hand, improvements in the level of technology have a mitigating effect on the negative impact of income in middle-income and low-income countries, contributing to the increase in $CO_2$ emission.

• The Journal of the Korea Contents Association
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• v.13 no.2
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• pp.475-487
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• 2013

The aim of this study is to examine an existence of mutual interdependency in terms of military expenditure and arms imports between Northeast Asian countries such as South Korea, North Korea, China, Japan, and U.S. Recently, the mood of post cold war and intensified globalization lead to be disarmament in pursuing a policy on national defence in many countries. Since potential menace to national security has been receiving more concern rather than a direct armed clash, mutual interdependency on military spending should be fully understood. For a methodological tools, ${\beta}$ and ${\sigma}$-convergences, convergence with rational expectation, and Granger causality test are employed. Empirical evidence shows that the convergences which are evaluated by ${\beta}$, ${\sigma}$, and by a model based on rational expectation are in general revealed, and differences are more sensitive to a military decision making procedures. Granger causality, however, is not being existed. To this end, it would be concluded that the Northeast Asian countries are going with a trend in the world than forming their own tendency in this region.

• Journal of Astronomy and Space Sciences
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• v.12 no.1
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• pp.133-142
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• 1995

We studied the nonlinear estimation problem of extended Kalman filter and appled this method to LEO satellite system. Through this method the performance of extended Kalman filter was analyzed. There were certain presumption taken; J2 and atmospheric drag were simply considered in the dynamic model of LEO satellite and the system noise error of $\sigma_r$=150m, $\sigma_r$=10m/s was presumed in the observation data. As results of this simulation, the overall state estimation errors of extended Kalman filter were within the presumed error range and also the ability of performance was maximized when the condition was the state process noise Q has the 1/10 level of covariance matrix Po.

• Korea Trade Review
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• v.43 no.1
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• pp.47-67
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• 2018

This study analyzed whether the poverty level among Asian countries has converged, by using data for the 'globalization period'. In particular, we analyzed the impact of trade on convergence by quantitative analysis using two indices; the head count ratio (H) and the human development index (HDI). The σ-convergence measurement and β-convergence measurement method, commonly used in the field of economic growth, are used for the analysis method. Results show that poverty rates have declined on average during the analysis period and there has been an increase in HDI. It seems that there has been improvement regarding poverty. However, this trend is only an indication of the average trend of Asian countries as a whole. As for the convergence between countries, which is the focus of this study, the HDI index shows the converges among countries while the H index does not show significant convergence among countries. It is also difficult to determine that trade has a statistically significant impact on the poverty rate convergence. However, in the case of HDI convergence, trade has contributed to increasing the convergence rates. This results might show that globalization does not guarantee the convergence among countries, and thus, we need to have additional policy in order to reduce the poverty.

• Annual Conference of KIPS
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• 2005.11a
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• pp.1019-1022
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• 2005

본 연구는 기업이 경영혁신 방침으로 Six Sigma 추진시 정보보호영역에서의 과제선정에 대한 기준을 제시한다. 기업은 윤리경영을 기초로 사업과 서비스를 통한 수익창출을 목적으로 한다. 기업은 안정적인 사업, 서비스의 정보환경을 확보,유지하기 위해 지속적인 보안활동을 통하여 Risk 를 줄이는 작업을 해오고 있다. 기업의 정보보호 활동과 패턴은 초기의 정보보호 기본기능을 도입, 구축하는 단계에서 탈피하여, 점진적으로 종합적인 관리체계로 수렴되고 있으며 산출되는 관련 정보와 Data 의 정규화를 기초로 정량적으로 관리가 이루어 지는 시점에 와 있다. 그러나, 정보보호 침해사고 예방 및 대응활동, 예측 불허한 상황에서 발생되는 보안사고, 책임문제의 발생, 정성적으로 관리되는 상황 등은 정보보호 영역의 Six Sigma 추진시 과제선정의 어려움으로 작용한다. 정보보호 영역에서 Six Sigma 과제 선정은 일반적인 Six Sigma 과제 선정과는 다르게 정보보호 특성을 고려하여 선정하여 추진하는 것이 바람직하다. 정보보호 활동에 대한 기업의 투자효과도 비재무적 성과외에 경제적 가치요소를 기초로 재무적 성과를 산출하고, 관리하여야 한다. 국내 기업들이 Six Sigma 를 경영혁신 기법으로 확대 적용하고 있는 상황에서 정보보호 영역의 Six Sigma 과제선정에 대한 제안을 통하여 정량적 목표수준 관리에 의한 성공적인 Six Sigma 성과를 달성할 수 있도록 함에 있다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.19 no.2
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• pp.147-154
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• 2001

The development of equipments which are for the collection and processing of digital images in digital photogrammetry is actively performed at the research about practical use. The close-range digital photogrammetry is widely using to determine accurate position, feature, and size of objects. The goal of this study is to judge the precise surveying possibility of a streamline object, like a vehicle, using digital close-range photogrammetry. The standard deviation of the calculated coordinates is respectively ${\sigma}_x$=0.434mm, ${\sigma}_y$=0.619mm, ${\sigma}_z$=0.387mm. The result values is enough to converge an accuracy required for the field of an automobile design. Therefor we suggest that the digital close-range photogrammetry could be use for the majority of industries.

• Environmental and Resource Economics Review
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• v.23 no.1
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• pp.67-89
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• 2014

This paper uses patent data of OECD countries in order to investigate if there is converging tendency in renewable energy area. We used the concepts of sigma convergence and beta convergence to measure the convergence. GINI coefficient, HH index are also borrowed from other area of economics. The results show that technology level does not seem to have been converging in this area. Even though the number of patent in relatively less advanced countries has been increased a lot, we could find no evidence that there is the tendency that the gap among the countries have been narrowed. This is quite different from the results of IT industry or other industry since we could find the converging tendency in the data of those industries. Instead, it seems that there is the convergence club among most advance countries in renewable energy area.

• Journal of the Korea Convergence Society
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• v.7 no.4
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• pp.217-227
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• 2016

This paper analyzes whether social welfare services converge across the regions. We tested whether local social welfare services converge considering the congestion rate of local social welfare services during the 1985-2013 periods in Korea, using the sixteen higher level local governments panel data. The main findings are as follows. First, the absolute level of local social welfare services converge so that the -convergence exists. Second, the growth rate of local social welfare services increases as the intial level of local social welfare services is lower so that there exists -convergence. The policy implications of our findings are as follows. The local government had better consider the presence of local social welfare services in policy decision making. Also, fundamentally the social welfare policies had better be executed by the central government rather than local governments, since the national minimum welfare must be provided.