• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.556-559
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• 2012

CTC(Connected Target Coverage) 문제는 주어진 전체 타겟을 관측하고 관측한 데이터를 싱크노드까지 전송하는데 관여하는 센서집합의 개수를 최대화하여 네트워크 수명을 최대화하는 문제이다. 본 논문은 확률 센싱 및 연결성 모델을 기반으로 CTC문제에 접근한다. CTC문제를 해결하기 위해 휴리스틱 알고리즘인 CWGC-PM 알고리즘을 제안하고 시뮬레이션을 통해 알고리즘이 CTC문제를 해결하기에 적합함을 보인다. 또한 확률모델이 다양한 커버리지 및 연결성 요구조건에 적용될 수 있음을 보인다.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.564-566
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• 2012

무선 센서 네트워크에서 관심지역이 배치된 센서들에 의하여 모두 관측되고 이의 데이터가 싱크노드까지 전달되는 동시에 네트워크의 수명을 최대화하도록 센서들을 배치하는 연구는 중요하다. 본 논문에서는 센서 에너지 소모의 균등화를 통해 네트워크 수명의 최대화를 이루기 위해 불균등 분포를 따르면서 네트워크의 기능이 올바르게 동작할 수 있도록 하는 센서의 배치 패턴을 제시한다.

• IEMEK Journal of Embedded Systems and Applications
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• v.14 no.4
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• pp.219-226
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• 2019

One of the most widely studied protocols for tactical ad-hoc networks is Optimized Link State Routing Protocol (OLSR). As for OLSR research, most research work focus on reducing control traffic overhead and choosing relay point. In addition, because OLSR is mostly dependent on link detection and propagation, dynamic Hello timer become research challenges. However, different timer interval causes imbalance of link validity time by affecting link lifetime. To solve this problem, we propose a weighted topology graph model for constructing a robust network topology based on the link validity time. In order to calculate the link validity time, we use control message timer, which is set for each node. The simulation results show that the proposed mechanism is able to achieve high end-to-end reliability and low end-to-end delay in small networks.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.556-559
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• 2011

CTC(Connected Target Coverage)문제는 주어진 전체 타겟을 관측하고 관측한 데이터를 싱크노드까지 전송하는데 관여하는 센서집합의 개수를 최대화하여 네트워크 수명을 최대화하는 문제이다. 본 논문은 센서가 타겟을 관측할 확률이 타겟과의 거리에 영향을 받는다고 가정하는 확률 커버리지 모델을 기반으로 CTC문제에 접근한다. CTC문제를 해결하기 위해 휴리스틱 알고리즘인 CWGC-PM 알고리즘을 제안하고 시뮬레이션을 통해 알고리즘이 CTC문제를 해결하기에 적합함을 보인다.

• ETRI Journal
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• v.46 no.2
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• pp.205-217
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• 2024

We propose a bandwidth prediction approach based on deep learning. The approach is intended to accurately predict the bandwidth of various types of mobile networks. We first use a machine learning technique, namely, the gradient boosting algorithm, to recognize the connected mobile network. Second, we apply a handover detection algorithm based on network recognition to account for vertical handover that causes the bandwidth variance. Third, as the communication performance offered by 3G, 4G, and 5G networks varies, we suggest a bidirectional long short-term memory model with time distribution for bandwidth prediction per network. To increase the prediction accuracy, pretraining and fine-tuning are applied for each type of network. We use a dataset collected at University College Cork for network recognition, handover detection, and bandwidth prediction. The performance evaluation indicates that the handover detection algorithm achieves 88.5% accuracy, and the bandwidth prediction model achieves a high accuracy, with a root-mean-square error of only 2.12%.

• Journal of the Korean Geographical Society
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• v.37 no.2
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• pp.111-130
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• 2002

Major purposes of this stud? are to analyze Korean firms'innovation networks and sources of knowledge for innovation and to understand their spatial dimensions. In the innovation networks, parent firms are most important for subcontracting firms, while suppliers, customers and competitors are relatively important for independent firms. However, in the future innovation networks, it is expected that government-sponsored research institutions and university wilt become more important on the one hand, networks with foreign firms will become more important on the other hand. Regarding the process of innovation, distance does not matter for the acquisition of codified knowledge. Spatial proximity is, however, critical for the acquisition of tacit knowledge because discussions and researches in a research division within a firm, personal networks of CEO and workers who are responsible for innovation activity, and inter-firm relations with suppliers and customer in a region are regarded important as sources of tacit knowledge. Overall, the innovation networks are different between the Capital Region and non-Capital Region as well as between the industrial complex and non-industrial complex, suggesting that different regional innovation strategies and policies should be established and implemented by considering such regional specificities. Finally, based on the results of this study several policy implications are suggested.

• The Journal of Korean Academic Society of Nursing Education
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• v.30 no.2
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• pp.182-191
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• 2024

Purpose: The purpose of this study was to explore the characteristics of social networks among registered nurses in acute nursing care units. Methods: This study used a survey design. Four nursing units from two acute hospitals were selected using a convenience method, and 83 nurses from those nursing units participated in the study in July 2022. The positive influences among nurses included friendship, collaboration, advice, and referent networks, and the negative influences included avoidance and bullying networks. Using the NetMiner program, the k-means clustering technique was applied to create groups of nodes with similar characteristics. The general characteristics of the participants were analyzed by mean, standard deviation, frequency, and ANOVA or chi-squared test. Results: As a result of dividing the 83 nurse participants into four clusters, positive influencers, silent peers, unwelcome peers, and active bullies were identified. Positive influence group nurses were frequently mentioned in the friendship, collaboration, advice, and referent networks. On the other hand, nurses in the unwelcome group and the active bullying group were frequently mentioned in the avoidance and bullying networks. Conclusion: Social networks that have a positive or negative impact on nursing performance are created through different relationships between nurses. Nurse managers can use the findings to create a more supportive and collaborative environment. Further research is needed to develop intervention programs to improve interactions and relationships between fellow nurses.

• ETRI Journal
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• v.25 no.6
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• pp.437-444
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• 2003

We derive a new joint power and rate control rule with which we can minimize the mean transmission delay in CDMA networks for a given mean transmission power. We show that it is optimal to respectively control the power inverse-linearly and the rate linearly to the square root of channel gain while maintaining the signal-to-interference ratio at a constant. We also show that the proposed joint power/rate control rule achieves excellent performance results in terms of the probability of the instantaneous delay being within a target delay against one-dimensional control schemes.

• ETRI Journal
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• v.30 no.2
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• pp.341-343
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• 2008

This letter presents an angular minimum spanning tree (AMST) algorithm for topology control in multi-hop wireless ad hoc networks. The AMST algorithm builds up an MST for every angular sector of a given degree around each node to determine optimal transmission power for connecting to its neighbors. We demonstrate that AMST preserves both local and network-wide connectivity. It also improves robustness to link failure and mitigates transmission power waste.

• Journal of Korea Technology Innovation Society
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• v.16 no.3
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• pp.861-882
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• 2013

This study analyses interorganizational innovation networks empirically in the Korean biotechnology industry, based on systems of innovation approach. Empirical findings of this study are as follows. Innovation networks have not been well developed in the Korean biotechnology industry. Main agents who participate in innovation networks are workers at venture firms, university professors, researchers at government-sponsored research institutions. They all recognize the positive effects of innovation networks. The enhancement of participation willingness and competency of agents, the enrichment of trust and control among agents, and the effective acquisition of the useful technology and resources in innovation networks will largely contribute to development of innovation networks in the Korean biotechnology industry.