• International Journal of Computer Science & Network Security
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• 제24권2호
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• pp.95-100
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• 2024

Cyclic Delay Diversity (CDD) is a diversity scheme used in OFDM-based telecommunication systems, transforming spatial diversity into frequency diversity and thus avoiding intersymbol interference without entailing the receiver to be aware of the transmission strategy making the signal more reliable achieving full diversity gain in cooperative systems. Here the analyzation of the influence of CDD-SC scheme in Cognitive Radio Network (CRN) is done with the challenge of overcoming the complication called channel estimation along with overhead in CNR. More specifically, the closed-form expressions for outage probability and symbol error rate are divided under different frequencies among independent and identically distributed (i.i.d.) frequency selective fading channel model i.e., the signal is divided into different frequencies and transmitted among several narrow band channels of different characteristics. It is useful in the reduction of interference and crosstalk. The results reveal the diversity order of the proposed system to be mainly affected by the number of multipath components that are available in the CNR.

• Journal of Communications and Networks
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• 제12권1호
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• pp.11-18
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• 2010

Diversity-multiplexing tradeoff (DMT) is an efficient tool to measure the performance of multiple-input and multiple-output (MIMO) systems and cooperative systems. Recently, cooperative multicast system with wireless network coding stretched tremendous interesting due to that it can drastically enhance the throughput of the wireless networks. It is desirable to apply DMT to the performance analysis on the multicast system with wireless network coding. In this paper, DMT is performed at the three proposed wireless network coding protocols, i.e., non-regenerative network coding (NRNC), regenerative complex field network coding (RCNC) and regenerative Galois field network coding (RGNC). The DMT analysis shows that under the same system performance, i.e., the same diversity gain, all the three network coding protocols outperform the traditional transmission scheme without network coding in terms of multiplexing gain. Our DMT analysis also exhibits the trends of the three network coding protocols' performance when multiplexing gain is changing from the lower region to the higher region. Monte-Carlo simulations verify the prediction of DMT.

• 산업경영시스템학회지
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• 제40권1호
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• pp.144-149
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• 2017

This study empirically analyzes the effect of IT SME ventures' external information network diversity on their production period reduction and productivity improvement generated from technology development. This research constructs a mediating model based on the open innovation perspective and tests it with the 138 samples of South Korean IT SME ventures based on the ordinary least squares regression. This research is expected to make a good contribution by shedding a new light on the following three points about the critical role of IT SME ventures' external information network diversity in increasing their production period reduction and productivity improvement generated from technology development which has scarcely been illuminated in the extant studies in the field of the management of technology for SMEs. First, IT SME ventures' external information network diversity positively influences their production period reduction. Second, the external information network diversity positively influences IT SMEs' ventures' productivity improvement. Third, IT SME ventures' production period reduction partially mediates the influence of IT SME ventures' external network diversity on their productivity improvement. These three fresh points are expected to provide useful theoretical and practical implications. Related to the theoretical implication, this research provides a fresh implication that IT SME ventures' external information network diversity positively influences not only their production period reduction but also productivity improvement generated from technology development. Concerning the practical implication, this study suggests that the CEOs in IT SME ventures make strategic efforts to use more diverse external information sources in order to increase their production period reduction and productivity improvement generated from technology development.

• 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.

• 기업가정신과 벤처연구
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• 제21권1호
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• pp.43-59
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• 2018

본 연구는 벤처캐피탈 신디케이트의 다양성과 그 신디케이트가 지원하는 벤처 기업의 IPO 사이의 관계에 대해 조사하였다. 구체적으로는 Harrison and Klein의 다양성에 대한 세 가지 분류(Separation, Variety, and Disparity)를 기반으로 하여, 벤처캐피탈 신디케이트에 적용되는 세 가지 종류의 다양성(Capacity diversity, Expertise diversity, Network diversity)을 제시한 뒤, 각 다양성이 성과에 미치는 효과를 분석하였다. 이를 검증하기 위하여 6,268개의 벤처캐피탈에 의한 1,127건의 벤처캐피탈 신디케이트 투자를 2단계 최소 자승법을 통하여 분석 한 결과, 제시된 가설 모두를 유의미하게 지지하는 것으로 나타났다. 세 다양성 중에서, Capacity다양성의 경우 성과를 감소시키지만, Expertise 다양성과 Network 다양성은 성과를 향상시키는 것으로 드러났다.

• 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.

• Journal of Information Technology Applications and Management
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• 제22권3호
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• pp.129-141
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• 2015

The purpose of this study is to provide an explanation for the association between the characteristics of a network and the type of innovation by considering the effect of absorptive capacity. To do so, this study examined the moderating effects of absorptive capacity on the characteristics of network-innovation relationship in a technical-driven venture company. In order to obtain a better understanding about consequences caused by interfirm network, information was obtained from 169 Korean IT venture companies. Results confirmed that the network diversity is positively associated with exploration. Our results also suggested that the network strength is positively associated with exploitation. Finally, we found a positive two-way interaction between absorptive capacity and the network diversity-exploration relationship. Then, we discussed implications and directions for future research.

• 방송공학회논문지
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• 제17권1호
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• pp.95-107
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• 2012

네트워크 코딩은 멀티캐스트 네트워크에서 전송량을 증가시키기 위해 제안된 기법으로 최근에는 다수의 사용자가 성능 향상을 위해서로의 자원을 공유하는 협력통신에 네트워크 코딩을 적용하는 연구가 활발히 진행 중이다. 네트워크 코딩 기반의 협력통신에서 사용자는 자기 자신의 데이터와 다른 사용자의 데이터를 네트워크 코딩 연산을 통해 결합하여 전송한다. 기존의 연구에서는 네트워크 코딩을 기반으로 한 적응형 복호 후 전송(Network-Coding-based Adaptive Decode-and-Forward, NC-ADF) 방식이 다이버시티(diversity) 이득과 추가적인 전송량 증대를 가져올 수 있음을 보였다. 본 논문에서는 기존 프로토콜의 성능 증대와 네트워크 코딩의 이득을 극대화 하기 위해 사용자간 채널의 상태에 따라 증폭 후 전송(Amplify-and-Forward, AF) 방식과 복호 후 전송(Decode-and-Forward, DF) 방식을 적응적으로 적용한 새로운 네트워크 코딩 기반의 협력통신 기법을 제안하였다. 또한 제안한 기법의 아웃티지 확률을 구하고 높은 SNR 영역에서 최대 다이버시티 차수(full diversity order)를 가짐을 보였다. 나아가 추가적인 성능 향상을 위해 본 논문에서 제안된 기법에 의한 아웃티지 확률을 기반으로 최적의 전송 파워 비율을 구하였다.

• 한국정보과학회논문지:데이타베이스
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• 제37권4호
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• pp.209-219
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• 2010

최근 빠르게 확산되고 있는 온라인 소셜 네트워크 서비스는 수많은 데이터를 저장하고 이를 분석하여 여러 연구 분야에 활용하고 있다. 정보의 효율성을 높이기 위해 기업이나 공공기관은 자신들이 가진 데이터를 배포하고, 배포된 데이터를 이용하여 여러 목적에 사용한다. 그러나 배포되는 소셜 네트워크에는 개인과 관련된 정보가 포함되어 있으므로 개인 프라이버시가 노출될 수 있는 문제가 있다. 배포되는 소셜 네트워크에서 단순히 이름 등의 식별자를 지우는 것으로는 개인 프라이버시 보호에 충분하지 않으며, 소셜 네트워크가 가진 구조적 정보에 의해서도 개인 프라이버시가 노출될 수 있다. 본 논문에서는 내용 정보를 포함하고 있는 소셜 네트워크 배포 시 개인 프라이버시 노출에 이용되는 복합된 공격법을 제시하고 이를 방지할 수 있는 새로운 모델인 $\ell$-차수 다양성($\ell$-degree diversity)을 제안한다. $\ell$-차수 다양성은 소셜 네트워크 데이터 배포에서 $\ell$-다양성을 최초로 적용한 모델이며 높은 정보 보존율을 가짐을 실험을 통해 볼 수 있다.

• Asia pacific journal of information systems
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• 제26권4호
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• pp.477-488
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• 2016

New technology development capability plays a key role in making small- and medium-sized enterprises (SMEs) increase their innovation performance, such as in product or process innovation. To examine the influencing factors of SMEs' new technology development capability, this study empirically analyzes the mediating effects of SMEs' process design capability and product interior design capability on the positive association between their external information network diversity and new technology development capability. This study performs the ordinary least squares regression on a sample of 2,000 South Korean SMEs. Results reveal that SMEs' process design capability fully mediates, and product interior design capability partially mediates the positive association between the external information network diversity and new technology development capability.