• 전기전자학회논문지
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• 제13권2호
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• pp.220-223
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• 2009

A simple measurement system is built to estimate the dual-antenna diversity gain at 2.4GHz easily in open lab environment. To obtain multipath fading propagation channel, the system consists of two transmission horn that placed on opposite direction and a rotating stage mechanically changing the position of test dual-antenna with time over distance greater than one wavelength. Estimated diversity is nearly same as theoretical value such that measured diversity gain of 30mm separated is about 6dB similar to theoretical value of 5.7dB and increases monotonically with the increasing separation distance as predicted by the theory. Proposed measurement system that is simple enough to fit in a small space can evaluate the performance of various dual-antennas with a reasonable accuracy with lower 5% difference between the ten sets of measured waveform distribution and theoretical Rayleigh cumulative distribution.

• 디지털융복합연구
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• 제11권11호
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• pp.219-231
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• 2013

기업은 불확실한 환경 하에서 지속적인 성장을 하기 위해 성과측정시스템(performance measurement systems, 이하 'PMS'라 함)을 구축 및 활용하고 있다. 대부분의 PMS에 관한 실증연구들은 조직차원에서 많은 연구가 이루어져 왔다. 성과측정지표의 다양성이 조직구성원들의 행동에 미치는 영향에 관한 연구는 많이 부족하며, 조직수준의 분석이 아닌 개인행동에 대한 세부적인 조사를 수행하는 연구는 의미가 있을 것이다. 따라서 본 연구는 성과측정지표의 다양성과 관리적 성과간의 관계에서 공정성과 조직시민행동의 매개역할을 연구하였다. 연구결과, 성과측정지표의 다양성과 관리적성과 간의 관계에서 공정성의 매개역할과 공정성과 관리적성과 간의 관계에서 조직시민행동의 매개역할을 발견하였다.

• ETRI Journal
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• 제36권2호
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• pp.188-196
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• 2014

This paper describes a simple delay diversity technique for terrestrial digital multimedia broadcasting (T-DMB) and digital audio broadcasting in a single-frequency network (SFN). For the diversity technique, a delay diversity scheme is adopted. In the delay diversity scheme, a non-delayed signal is transmitted in the first antenna, and delayed versions of the signal are transmitted in each additional antenna. For an SFN environment with multiple transmitters, delay diversity can be executed by controlling the emission times of the transmitters. This SFN delay diversity scheme does not require any hardware changes in either the transmitter or receiver, and perfect backward compatibility can be acquired. To evaluate the performance improvement, laboratory tests are executed with various types of commercial T-DMB receivers as well as a measurement receiver. The improvement in the bit error rate performance is evaluated using a measurement receiver, and an improvement of the threshold of visibility value is evaluated for commercial receivers. Test results show that the T-DMB system can obtain diversity gain using the described technique.

• Asian Journal for Public Opinion Research
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• 제1권2호
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• pp.103-127
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• 2014

This study reviews existing research on the measurement of and the relationship between political diversity and political participation. It addresses the inconsistency in the arguments of existing studies researching the influence of political diversity on political participation. It attempts to find the cause in the variety of approaches to conceptualize and operationalize the two variables. As the measure of political diversity, political network heterogeneity and network attributes are discussed in detail in specific relation to political participation. As for political participation, an in-depth analysis of various ways to understand different forms of political involvement is presented. Implications for public opinion research are discussed.

• Journal of Communications and Networks
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• 제13권3호
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• pp.240-249
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• 2011

Cooperative diversity protocols have attracted a great deal of attention since they are thought to be capable of providing diversity multiplexing tradeoff among single antenna wireless devices. In the high signal-to-noise ratio (SNR) region, cooperation is rarely required; hence, the spectral efficiency of the cooperative protocol can be improved by applying a proper cooperation selection technique. In this paper, we present a simple "cooperation selection" technique based on instantaneous channel measurement to improve the spectral efficiency of cooperative protocols. We show that the same instantaneous channel measurement can also be used for relay selection. In this paper two protocols are proposed-proactive and reactive; the selection of one of these protocols depends on whether the decision of cooperation selection is made before or after the transmission of the source. These protocols can successfully select cooperation along with the best relay from a set of available M relays. If the instantaneous source-to-destination channel is strong enough to support the system requirements, then the source simply transmits to the destination as a noncooperative direct transmission; otherwise, a cooperative transmission with the help of the selected best relay is chosen by the system. Analysis and simulation results show that these protocols can achieve higher order diversity with improved spectral efficiency, i.e., a higher diversity-multiplexing tradeoff in a slow-fading environment.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.609-612
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• 2003

For combating multipath fading in wireless radio environment, diversity schemes is useful. In this paper, for performance improvement of polarization diversity system, we analyzed a two-branch polarization diversity at the receiving end of a mobile link when the transmitter emits a circularly polarized wave. And In order to calculate the correlation coefficient considering the XPD(cross polarization discrimination) between the received signals for the two diversity branches, a simple theoretical model of circular polarization diversity is adopted and calculate correlation coefficient. From the analysis results, it is seen that the correlation coefficient of circular polarization diversity evaluated by the XPD is less than that of vertical polarization diversity. And also, we designed and fabricated circular polarization diversity system with microstrip antenna. we analyzed data measured in indoor NLOS environment using fabricated circular polarization diversity system. From the measurement results, it is clearly seen that the diversity effect of circular polarization diversity system is higher 3dB than vertical polarization diversity system.

• 한국언론정보학보
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• 제51권
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• pp.136-155
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• 2010

미디어 다양성은 글로벌 시장에서의 경쟁이라는 '환상의 짝꿍'과 더불어 한국 미디어 정책을 규정하는 화두로 등장했다. 미국식 기능 행태주의가 주도하는 미디어 정책은 다양성을 시장경쟁, 소비주체의 자유로운 선택이라는 좁은 울타리에 가둔다. 이에 본 논문은 다양성 그 자체를 하나의 완결한 정책목표로 보는 시각에 근본적인 문제제기를 하고자 한다. 다양성이 미디어 정책 담론의 전면에 등장하는 계기를 한국의 중첩적 정치 경제 맥락 속에서 파악하면서, 본 논문은 기존 계량주의 다양성 연구를 비판적으로 분석한다. 나아가 미디어 다양성이 '측정의 과학'에 과도하게 집착해 탈정치화하는 경향을 주목하며 문화연구자들이 미디어 다양성을 보다 진보적으로 전취하기 위한 몇 가지 제안을 하고자 한다. 핵심적인 주장은 미디어 다양성은 시장의 경쟁과 미디어 상품의 다양화라는 신자유주의의 경제논리를 넘어서야 한다는 것이다. 비판적 문화연구자들은 미디어 다양성을 한국 민주주의의 심화라는 보다 큰 정치 프로젝트 속에서 미디어 공공성의 강화, 독립 대안 미디어에 대한 실질적 지원, 급진적 정체성의 정치학 등의 전략과 함께 고려해야 한다.

• 한국ITS학회 논문지
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• 제7권2호
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• pp.56-61
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• 2008

움직이는 차량 내에서 WiBro 서비스를 사용하기 위해서는 Multi-Fading 환경에 강한 Diversity 안테나 시스템이 필수적으로 요구된다. 일반적으로 Diversity System Gain을 올리기 위해서는 안테나간의 높은 격리도를 확보해야 한다. 본 논문에서는 안테나간의 격리도를 확보하기 위하여 안테나의 편파를 직교시키는 편파 다이버시티 안테나를 제안하였다. 또한 한정된 크기의 Ground를 공유한 상태에서 안테나 간의 편파특성을 개선하기 위한 HWLLA (Half Wave Length Loaded Antenna)구조를 설계 및 측정하였다. 결과적으로 두 Diversity 안테나 간의 격리도가 HWLLA 타입을 적용했을 때 PIFA Type보다 12 dB 이상 개선되었다.

• Asian Journal of Innovation and Policy
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• 제2권1호
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• pp.37-62
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• 2013

Many scholars have persevered in understanding the convergence process by developing a measurement that reflects the characteristics of the convergence phenomenon as a process. Recently a series of studies suggested a framework in terms of diversity and coherence. However, an index for coherence is required to reflect the vital features of the conceptual definition, and thus a new index for coherence is proposed in this paper. Technology Convergence Index combines diversity and coherence and indicates the degree of the convergence in information computer technology (ICT), biotechnology (BT) and nanotechnology (NT) sectors. The index can not only be used to track each technology field that consists of a major technology sector, but also to compare other leading countries. Based on a comparison study between the United States and South Korea, the degrees of technology convergence of Korea in ICT, BT, and NT sectors have ameliorated.

• Current Optics and Photonics
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• 제6권5호
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• pp.473-478
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• 2022

To overcome the capture-range problem in phase-diversity phase retrieval (PDPR), a geometrical-optics initial-estimate method is proposed to avoid a local minimum and to improve the accuracy of laser-wavefront measurement. We calculate the low-order aberrations through the geometrical-optics model, which is based on the two spot images in the propagation path of the laser, and provide it as a starting guess for the PDPR algorithm. Simulations show that this improves the accuracy of wavefront recovery by 62.17% compared to other initial values, and the iteration time with our method is reduced by 28.96%. That is, this approach can solve the capture-range problem.