• Journal of Communications and Networks
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• v.1 no.2
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• pp.89-98
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• 1999

In a synchronization (sync) $network^1$containing N nodes, it is shown (Theorem 1c) that an arbitrarily connected sync network & is the union of a countable set of isolated connecting sync networks${&_i,i= 1,2,.., L}, I.E., & = \bigcup_{I=1}^L&_i$ It is shown(Theorem 2e) that aconnecting sync network is the union of a set of disjoint irreducible subnetworks having one or more nodes. It is further shown(Theorem 3a) that there exists at least one closed irreducible subnetwork in $&_i$. It is further demonstrated that a con-necting sync network is the union of both a master group and a slave group of nodes. The master group is the union of closed irreducible subnetworks in $&_i$. The slave group is the union of non-colsed irre-ducible subnetworks in $&_i$. The relationships between master-slave(MS), mutual synchronous (MUS) and hierarchical MS/MUS ent-works are clearly manifested [1]. Additionally, Theorem 5 shows that each node in the slave group is accessible by at least on node in the master group. This allows one to conclude that the synchro-nization information avilable in the master group can be reliably transported to each node in the slave group. Counting and combinatorial arguments are used to develop a recursive algorithm which counts the number $A_N$ of arbitrarily connected sync network architectures in an N-nodal sync network and the number $C_N$ of isolated connecting sync network in &. EXamples for N=2,3,4,5 and 6 are provided. Finally, network examples are presented which illustrate the results offered by the theorems. The notation used and symbol definitions are listed in Appendix A.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.189-190
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• 2016

요즘 사이버 공격이 많이 발생함에 따라 기존의 디지털 포렌식 뿐만 아니라 네트워크 트래픽을 수집해서 사이버 공격을 분석하는 네트워크 포렌식에 대한 연구가 많이 수행되고 있다. 그러나 네트워크 포렌식을 수행하기 위해서는 여러가지 어려움이 존재한다. 이러한 문제를 해결하기 위하여 우리는 이 논문에서 네트워크 악성행위를 분석하기 위한 시스템 및 방법을 제안한다.

• ETRI Journal
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• v.43 no.5
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• pp.932-940
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• 2021

Currently, research on network functions virtualization focuses on using microservices in cloud environments. Previous studies primarily focused on communication between nodes in physical infrastructure. Until now, there is no sufficient research on group key management in virtual environments. The service is composed of microservices that change dynamically according to the virtual service. There are dependencies for microservices on changing the group membership of the service. There is also a high possibility that various security threats, such as data leakage, communication surveillance, and privacy exposure, may occur in interactive communication with microservices. In this study, we propose an ID-based group key exchange (idGKE) mechanism between microservices as one group. idGKE defines the microservices' schemes: group key gen, join group, leave group, and multiple group join. We experiment in a real environment to evaluate the performance of the proposed mechanism. The proposed mechanism ensures an essential requirement for group key management such as secrecy, sustainability, and performance, improving virtual environment security.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.351-355
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• 2004

A multibeam switching satellite system technology have started localized development to overcome the limitation of the frequency resource and geostationary orbit existing relay type satellite transponder and the required performance of the spot beam, and looked around the configuration and functions of the multibeam switching satellite communication system. This paper proposed that operation scheme and network control features for service definition, network architecture, transmission method of the natural disaster service network and public communication service network using this system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.541-542
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• 2021

In this paper, we consider the straggled network treatment in multiple sensor groups. During the moving or the implement of mission, the departed network should be handled. The loss of network group affects the mission implement of overall sensor networks, and it also requests the immediate treatment. In urgent mission environments, the network management of mobile sink should be considered to the group damage.

• Journal of Information Processing Systems
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• v.13 no.2
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• pp.236-255
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• 2017

The rapid growth of smart devices demands an enhanced throughput for network connection sustainability during mobility. However, traditional wireless network architecture suffers from mobility management issues. In order to resolve the traditional mobility management issues, we propose a novel architecture for future wireless access network based on software-defined network (SDN) by using the advantage of network function virtualization (NFV). In this paper, network selection approach (NSA) has been introduced for mobility management that comprises of acquiring the information of the underlying networking devices through the OpenFlow controller, percepts the current network behavior and later the selection of an appropriate action or network. Furthermore, mobility-related scenarios and use cases to analyze the implementation aspects of the proposed architecture are provided. The simulation results confirm that the proposed scenarios have obtained a seamless mobility with enhanced throughput at minimum packet loss as compared to the existing IEEE 802.11 wireless network.

• Korean Journal of Psychosomatic Medicine
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• v.4 no.2
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• pp.226-244
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• 1996

This study was designed to evaluate the social support network of schizophrenic patients. 64 schizophrenic patients being treated as out-door patient were compared with 30 neurotic control patients. Schizophrenics were divided into positive, subpositive, subnegative and negative subgroups by present symptom and social network of both schizophrenics and control group were evaluated. The results are as follows: 1) Social network of schizophrenics was smaller than that of control group. Size of social network of schizophrenics was 10.6 and that of control group was 23.5. 2) In both kin and nonkin, social network of schizophrenics was smaller than that of control group. Of the kin, schizophrenics were more supported by wife or husband, father, and mother, but were less supported by brother, son and other relatives. 3) There was no difference in the kin or nonkin or total supporters between the four subgroups of schizophrenics. But, subgroup of schizophrenics which was divided as having negative symptom had smaller network than control group in active formal and informal supporters. 4) When divided into 4 support areas, schizophrenics was remarkably less supported in emotional, instrumental and appraisal support area than control group, but there was no difference in the informational support areas. 5) Compared with control group, schizophrenics more often mentioned parent and ten often mentioned nonkin supporter as the one that is most important to him. 6) Schizophrenics had smaller cluster and less leisure activity than control group. Subgroup of schizophrenics who was divided as having negative symptom had less frequency of leisure activity than other subgroups.

• Korean Journal of Health Education and Promotion
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• v.22 no.2
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• pp.173-193
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• 2005

Objectives: The purpose of this study is to analyze the peer group factor related to adolescent smoking in the social structure(network) of adolescent groups, by applying the theory of social network. Methods: The data was collected from boy students of one high school located in Gun-Po city of Kyonggi Province. The total number of the sample was 605(223 first grade, 198 second grade, 184 third grade). The survey using the questionnaire was carried out in April 2005. Social position is finally classified as clique member, liaison, isolate group by using the NetMiner II 2.5 version. Results: The current smoking rate was 15.0%, and the life-time smoking rate was 34.9%. The smoking rate increased significantly, as the grade went up. And it was significantly high among the group having smoking friends. The logistic regression analysis showed that the odds ratio of the smoking friends group was about 4 times higher than the no smoking friends group in experience of smoking. But the smoking rate was higher significantly in the isolate group within the network composed of 2. person's social-link. The odds ratio of the isolate group was about 4.5 times higher than the clique member. However, this pattern was not found in the network composed of 3 person's social-link. Therefore, the hypothesis that clique member would have a correlation with smoking was rejected. In reality, the isolate group had a tendency of smoking more frequently. Conclusions: The result of this study suggests that the role of the peer group in smoking is to be considered in the prevention program. More attentions should be paid for the isolate group.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.2011-2012
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• 2006

전력선 채널의 특성을 대표하는 배경 잡음과 전기기기에서 발생하는 충격잡음은 실증 시험을 통해 측정되거나 매체 자체의 특징을 수학적 기법을 통해 모델링하는 두 가지의 방법이 있다. 여타의 통신 시스템과 마찬가지로 채널에 대한 정확한 정보제공이 수신기의 성능 분석 및 향상을 가능케 한다. 최근 전력선 채널의 배경잡음이 무선통신 채널의 Nakagami-m 분포를 따른다는 측정결과가 발표되었다. 본 논문에서는 Nakagami-m 분포를 배경잡음으로 전력선 채널 모델링한 경우 평균값 등의 통계적 특성을 제공함으로서 수신기의 성능 분석 및 향상에 기여하고자 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.11a
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• pp.392-394
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• 2014

요즘 인터넷을 통하여 많은 사이버 공격이 일어나고 있다. 이에 대응하기 위하여 우리는 네트워크 패킷을 저장할 수 있는 사이버 블랙박스 시스템을 개발하고 사이버 블랙박스 시스템에서 수집한 많은 네트워크 패킷을 분석할 수 있는 효율적인 공격 원인 분석 알고리즘을 제안한다. 공격원인 분석 알고리즘을 통하여 우리는 사이버 공격에 발생했을 때 공격의 유입점이 어디이고 어떤 경로를 통해서 공격이 이루어졌는지 알 수 있다. 그 뿐만 아니라 숨겨진 피해자 발견 알고리즘을 통하여 알려진 피해자뿐만 아니라 알려지지 않은 다른 피해자를 찾을 수 있다.