• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.26 no.1
• /
• pp.114-121
• /
• 2022

In this paper, we consider a user centric clustering in order to guarantee the performance of the users in cell free multiple-input multiple-output (MIMO) network. In the user centric clustering scheme, by using large scale fading coefficients of the connected access points (APs), each user decides own cluster with the APs having the higher the large scale fading coefficients than threshold value compared to the highest large scale fading coefficient. In the determined user centric clusters, the APs design the beamformers and power allocations in the distributed manner and the APs cooperatively transmit data to users by using beamformers and power allocations. In the simulation results, we verify the performance of user centric clustering in terms of the spectral efficiency and we also find the optimal threshold value in the given configuration.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.27 no.2
• /
• pp.86-92
• /
• 2004

미국의 실리콘밸리와 대만의 신주공업단지는 종종 첨단 산업집적단지의 성공적 모델로 불리어진다. 이들 두 지역의 성공 및 경쟁력에 대한 지배적 설명은 전통적으로 경제활동의 공간적 집적이 가져다주는 경제적 이익을 제시하기 위해 사용된 "외부규모의 경제"에 이론적 기반을 두고 있다. 그러나, 외부경제란 개념만으로 이들 지역의 역동적 발전과 모방하기 힘든 경쟁력을 설명하기에는 부족함이 많았다. 본 논문은 이들 지역에서 역사적으로 전개되어진 기업과 외부 경제주체들과의 관계를 사회적 자본, 네트워크 기반 산업시스템 분석, 자원기반이론 등을 토대로 분석하여 이들 두 지역이 첨단집적단지로서의 성공요인과 경쟁우위에 대해서 살펴보고자 했다. 아울러 본 논문은 이들 두 지역에 있어서 발전적 협력관계를 분석함으로서 국내에서 이러한 첨단산업단지를 개발하고 발전시키기 위해 필요한 것이 무엇인지를 검토하고 이에 필요한 정책적 시사점을 몇 가지 제시했다.몇 가지 제시했다.

• Journal of Digital Contents Society
• /
• v.9 no.1
• /
• pp.33-39
• /
• 2008

Mobile Ad Hoc Network is easy to be attacked because nodes are distributed not network based infrastructure. Intrusion detection system perceives the trust values of neighboring nodes and receives inspection on local security of nodes and observation ability. This study applied clustering mechanism to reduce overhead in intrusion detection. And, in order to measure the trust values, it associates the trust information cluster head received from member nodes with its own value and evaluates the trust of neighboring nodes. Secure data transmission is received by proposed concept because the trust of nodes on network is achieved accurately.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2011.04a
• /
• pp.138-141
• /
• 2011

최근 유비쿼터스 컴퓨팅 시대로 진입하면서 센서 네트워크에 대한 관심이 증대되고 있다. 그 중에서 위치인식을 이용한 다양한 연구가 활발하게 진행되고 있다. 본 논문에서는 주파수의 회절 및 반사, 감쇄 현상을 최소화 하기 위해 모바일 노드가 속해 있는 클러스터부터 수신된 RSSI 값을 사용하여 위치 정보를 추출한다. 또한 가까운 라우터 노드에 더 높은 가중치를 주어 수신한 라우터노드들의 무게 중심을 노드의 위치로 판단하는 방법을 통하여 위치 정보를 추출하는 방법을 제안한다.

• Journal of the Korean association of regional geographers
• /
• v.20 no.3
• /
• pp.256-258
• /
• 2014

This paper aims at examining the role of university, industry and government, which constitute the triple-helix innovation system in hi-tech cluster, based on the case of the Research Triangle Park, North Carolina, USA. Firstly, the state government has played a catalytic role by building the horizontal governance of triple-helix actors. By doing so, the state government has made it possible for not only growing but also transforming the RTP as an high-tech cluster. Secondly, universities in the triangle area have played to some extent a limited role in sustaining the evolution of cluster. Thirdly, the RTP has long been dominated by a small group of large firms. However, the situation has been changed since 1990s, because new start-ups from universities and local large firms and the technology transfer activities between universities and firms have been increased in the RTP and its surrounding area. Finally, it argues that the continuous evolution of the RTP has been to some or large extent influenced by the transition from the exogenous development model to the endogenous development model.

• Journal of the Korea Society of Computer and Information
• /
• v.16 no.11
• /
• pp.17-24
• /
• 2011

Collaborative filtering system is the clustering about user is built and then based on that clustering results will recommend the preferred item to the user. However, building user clustering is time consuming and also once the users evaluate and give feedback about the film then rebuilding the system is not simple. In this paper, genre pattern of movie recommendation systems is being used and in order to simplify and reduce time of rebuilding user clustering. A Frequent pattern networks is used and then extracts user preference genre patterns and through that extracted patterns user clustering will be built. Through built the clustering for all neighboring users to collaborative filtering is applied and then recommends movies to the user. When receiving user information feedback, traditional collaborative filtering is to rebuild the clustering for all neighbouring users to research and do the clustering. However by using frequent pattern Networks, through user clustering based on genre pattern, collaborative filtering is applied and when rebuilding user clustering inquiry limited by search time can be reduced. After receiving user information feedback through proposed user clustering based on genre pattern, the time that need to spent on re-establishing user clustering can be reduced and also enable the possibility of traditional collaborative filtering systems and recommendation of a similar performance.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.8A
• /
• pp.791-800
• /
• 2010

Recently wireless sensor networks as a field of ubiquitous computing technology was in the limelight. To use and collect the necessary information, Sink node mobility is essential. TTDD(Two-Tier Data Dissemination) proposed most common technique associated with Mobile sink node in wireless sensor networks, but issues exist that the use of many control packet falls into the energy efficiency. The technique for solving problems is Cluster-Based Energy-efficient Routing protocol (CBPER). But CBPER does not transmit the data correctly to sink node or source node. In this paper, we propose An Energy-Efficient Routing Protocol based on Static Grid using mobile sink nodes in order to solve the data transmission failure and reduce the energy consumption in Wireless Sensor Networks. We have evaluated it with the NS-2 simulator. Our results show that the proposed protocol saves the energy consumption up to 34% in comparison with CBPER. We also prove that the proposed protocol can transmit more accurate data to the sink de than CBPER.

• Convergence Security Journal
• /
• v.13 no.4
• /
• pp.41-46
• /
• 2013

Routing protocol using in the existing wire network cannot be used as it is for efficient data transmission in MANET. Because it consists of only mobile nodes, network topology is changing dynamically. Therefore, each mobile node must perform router functions. Variety of routing attack like DoS in MANET is present owing to these characteristic. In this paper, we proposed cooperative-based detection method to improve detection performance of flooding attack which paralyzes network by consuming resource. Accurate attack detection is done as per calculated adaptively threshold value considered the amount of all network traffic and the number of nodes. All the mobile nodes used a table called NHT to perform collaborative detection and apply cluster structure to the center surveillance of traffic.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.11A
• /
• pp.903-911
• /
• 2011

In this paper we proposed an energy adaptive data aggregation and transmission mechanism to solve the problem of energy limitation in wireless sensor networks (WSNs). Hierarchical structure methods are wildly used in WSNs to improve the energy efficiency. LEACH and TEEN protocols are the typical techniques. In these methods, all nodes, including nodes who have sensed data to transmit and nodes who haven't, are set frame timeslots in every round. MNs (member nodes) without sensed data keep active all the time, too. These strategies caused energy waste. Furthermore, if data collection in MNs is same to the previous transmission, it increases energy consumption. Most hierarchical structure protocols are developed based on LEACH. To solve the above problems, this paper proposed a method in which only MNs with sensed data can obtain allocated frame to transmit data. Moreover, if the MNs have same sensed data with previous, MNs turn to sleep mode. By this way redundant data transmission is avoided and aggregation in CH is lightened, too.

• Convergence Security Journal
• /
• v.9 no.2
• /
• pp.71-78
• /
• 2009

It is very difficult to apply previous security protocols to WSNs(Wireless Sensor Networks) directly because WNSs have resource constrained characteristics such as a low computing ability, power, and a low communication band width. In order to overcome the problem, we proposes a secure group communication scheme applicable to WSNs. The proposed scheme is a combined form of the TEEN(Threshold sensitive Energy Efficient sensor Network protocol) clustering based hierarchical routing protocol and security mechanism, and we assume that WSNs are composed of sensor nodes, cluster headers, and base stations. We use both private key and public key cryptographic algorithms to achieve an enhanced security and an efficient key management. In addition, communications among sensor nodes, cluster headers, and base stations are accomplished by a hierarchical tree architecture to reduce power consumption. Therefore, the proposed scheme in this paper is well suited for WSNs since our design can provide not only a more enhanced security but also a lower power consumption in communications.