• 한국정보통신학회논문지
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• 제17권8호
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• pp.1804-1810
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• 2013

본 논문에서는 듀얼 홉 중계 시스템에서의 협력 전송 방식과 비협력 전송 방식간의 효율적인 선택을 통하여 아웃티지 성능을 향상시키는 기회적 협력 방식에 대해 연구한다. 특히, 디코딩 후 전달 중계 시스템에서 부분 중계 노드 선택 기법을 이용한 기회적 협력 방식의 아웃티지 성능을 분석한다. 여기서, 독립적이고 균일 분포를 갖는 레일레이 페이딩 채널을 가정하여 정확한 아웃티지 확률 표현식과 점근적인 아웃티지 확률 표현식을 유도한다. 수치적 결과에서, 유도된 표현식들을 검증하고, 데이터율의 목표치와 중계 노드 수에 대한 아웃티지 성능을 분석한다. 또한, 기존의 협력 방식과 기회적 협력 방식의 아웃티지 성능을 비교한다.

• 품질경영학회지
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• 제50권1호
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• pp.63-76
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• 2022

Purpose: The purpose of this study is to analyze the effects of risk perception and opportunistic behavior on project performance and the moderating effect of cooperation in this relationship through literature review to identify factors affecting the performance of large-scale nuclear power plant construction projects. Methods: This study conducted a survey on nuclear power plant construction project participants and verified the hypothesis using statistical methods. Results: The results of this study are as follows; First, risk perception appeared to have a positive effect on opportunistic behavior, and it was confirmed that opportunistic behavior among participating companies could occur even in nuclear power plant construction projects. Second, it has been proven that risk perception has a negative effect on project performance as suggested in previous studies. Third, in the relationship between opportunistic behavior and project performance, it was found that opportunistic behavior had a negative effect on project performance. Finally, cooperation was found to have a moderating effect on the relationship between performance risk and project performance. Conclusion: This study is a case of empirical analysis targeting nuclear power plant construction project workers, and provided a basis for reference in future related academic research and project implementation.

• ETRI Journal
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• 제33권2호
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• pp.287-290
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• 2011

We consider a two-hop multiple-relay network implemented with opportunistic decode-and-forward cooperative strategy, where the first hop and second hop links experience different fading (Rayleigh and Rician). We derive the exact expressions of end-to-end outage probability and analyze the approximate results in high signal-to-noise ratio region. The analysis shows that the same diversity order can be achieved even in different mixed fading environments. Simulation results are provided to verify our analysis.

• 한국통신학회논문지
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• 제34권3A호
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• pp.244-257
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• 2009

본 연구에서는 우선 삼성 전자에서 제시한 MMR에서 기회적 패킷 스케줄링 방법을 분석 하고 시뮬레이션을 통해 효율성을 검증해 보았다. 아울러 제안된 방법 하에서 수율과 공평성 사이의 관계를 조사 하였다. 본 연구의 주된 목적은 MMR에서 사용자의 QoS 요구 조건을 고려한 기회적 패킷 스케줄링 방법을 제안 하는 것이다. 시뮬레이션을 사용하여 제안된 방법의 성능을 i) QoS 를 고려하지 않은 순수한 기회적 패킷 스케줄링 방법의 성능 그리고 ii) QoS 만을 고려하고 기회적 패킷 스케줄링은 활용하지 않는 패킷 스케줄링 방법의 성능과 비교 분석하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권1호
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• pp.152-171
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• 2019

In opportunistic networks, nodes may appear some selfishness while transmitting the message, however, most of the existing research works consider the individual selfishness or social selfishness respectively, and these two types of selfishness may coexist in opportunistic networks. In this paper, we propose an Incentive Aware Routing based on Game Theory for selfish OPPNETs, named IAR-GT, which uses Rubinstein-Stahl bargaining game model to incentivize selfish nodes cooperation in data forwarding. IAR-GT scheme not only considers the resources of nodes, but also uses a new method to calculate the social ties between them. Trace-driven simulations show that our incentive aware routing scheme achieves better performances than comparing schemes under two types of selfishness coexistence environments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권10호
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• pp.4662-4677
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• 2018

The dynamic opportunistic device-to-device (DO-D2D) network will frequently emerge in the fifth generation (5G) wireless communication due to high-density and fast-moving mobile devices. In order to improve the Quality of Experience (QoE) of users with different computing capacity devices in the DO-D2D network, in this paper, we focus on the study of how to reduce the packets retransmission delay and satisfy heterogeneous devices. To select as many devices as possible to transmit simultaneously without interference, the concurrent transmitters-selecting algorithm is firstly put forward. It jointly considers the number of packets successfully received by each device and the device's connectivity. Then, to satisfy different devices' demands while primarily ensuring the base-layer packets successfully received by all the devices, the layer-cooperation instantly decodable network coding is presented, which is used to select transmission packets combination for each transmitter. Simulation results illustrate that there is an appreciable retransmission delay gain especially in the poor channel quality network compared to the traditional base-station (BS) retransmission algorithm. In addition, our proposed algorithms perform well to satisfy the different demands of users with heterogeneous devices.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권4호
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• pp.973-988
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• 2012

Delay tolerant networks (DTNs) characterized by the lack of guaranteed end-to-end paths exploit opportunistic data forwarding mechanism, which depends on the hypothesis that nodes are willing to store, carry, and forward the in-transit messages in an opportunistic way. However, this hypothesis might easily be violated by the presence of selfish nodes constrained with energy, bandwidth, and processing power. To address this problem, we propose a practical reputation-based incentive scheme, named PRI, to stimulate honest forwarding and discipline selfish behavior. A novel concept of successful forwarding credential and an observation protocol are presented to cope with the detection of nodes' behavior, and a reputation model is proposed to determine egoistic individuals. The simulation results demonstrate the effectiveness and practicality of our proposal.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권3호
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• pp.1481-1501
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• 2019

In opportunistic network, the behavior of a node is autonomous and has social attributes such as selfishness.If a node wants to forward information to another node, it is bound to be limited by the node's own resources such as cache, power, and energy.Therefore, in the process of communication, some nodes do not help to forward information of other nodes because of their selfish behavior. This will lead to the inability to complete cooperation, greatly reduce the success rate of message transmission, increase network delay, and affect the overall network performance. This article proposes a hybrid incentive mechanism (Mim) based on the Reputation mechanism and the Credit mechanism.The selfishness model, energy model (The energy in the article exists in the form of electricity) and transaction model constitute our Mim mechanism. The Mim classifies the selfishness of nodes and constantly pay attention to changes in node energy, and manage the wealth of both sides of the node by introducing the Central Money Management Center. By calculating the selfishness of the node, the currency trading model is used to differentiate pricing of the node's services. Simulation results show that by using the Mim, the information delivery rate in the network and the fairness of node transactions are improved. At the same time, it also greatly increases the average life of the network.

• 한국전자파학회논문지
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• 제22권1호
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• pp.24-29
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• 2011

네트워크 부호화를 이용한 양 방향 중계 기법은 기존의 단 방향 중계 프로토콜보다 송신 시간을 줄임으로써 전송량을 높일 수 있는 장점을 가지며, 부호화 협력 프로토콜은 물리층에서 이루어지는 부호화를 적용한 알고리즘으로 프로토콜의 신뢰성을 높일 수 있는 장점을 가진다. 본 논문에서는 이러한 두 프로토콜의 장점을 결합한 양 방향 중계 네트워크에서의 부호화 협력 프로토콜을 제안하였다. 제안하는 프로토콜이 기존의 양 방향 증폭후 재전송 프로토콜보다 우수한 신뢰성과 전송량을 가지며, 기존의 양 방향 하이브리드 복호 후 재전송 프로토콜과 동일한 전송량을 가지면서 보다 우수한 신뢰성을 가짐을 시뮬레이션 결과를 통해 증명한다.

• 아태비즈니스연구
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• 제10권4호
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• pp.223-236
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• 2019

Governance can be defined as a concept that encompasses a series of processes including partner selection as well as control and coordination of collaboration to achieve common goals. The study examined efforts to mitigate the risks of opportunistic behaviors into partner selection, partner relationship, control mechanism, and conflict management. For cases that have achieved commercialization outputs with the participation of SMEs, data was collected and analyzed such as interviews with project managers and case records for seven months from October 2016. According to the analysis result, as the complexity increases, such as multilateral cooperation for the development of finished products, cooperation with a trusted partner rather than a partner who can perform a task well was preferred, and the process control was put ahead of the output control. Regarding the partner relationship, the relationship between the owner and the agent differed according to the point of view, and there was a lack of clear allocation of authority and responsibility as well as a reward for the result. In terms of the conflict management, most emphasis was on resolving conflicts or difficulties, and no attempt was made to utilize the positive aspects of the conflict. The structure of most industry-university-institute cooperation organizations is simply composed of the host and participating organizations, and the management regulations should be amended for companies, that put actual funds and use the outputs, to have the authority and responsibility as the owners, and be allowed to use the governance elements appropriately to take the lead as consumers.