• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.5
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• pp.794-804
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• 2018

Various applications running in computers exchange information in the form of packets through the network. Most packets are formatted into UDP/IP or TCP/IP standard. Network management administrators of enterprises and organizations should be able to monitor and manage packets transmitted over the network for Internet traffic measurement & monitoring, network security, and so on. The goal of this paper is to analyze the performance of several algorithms which closely examine and analyze payloads in a DPI(Deep Packet Inspection) system. The main procedure of packet payload analysis is to quickly search for a specific pattern in a payload. In this paper, we introduce several algorithms which detect a specific pattern in payloads, analyze the performance of them from three perspectives, and suggest an application method suitable for requirements of a given DPI system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.8
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• pp.33-41
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• 2007

The IEEE 802.11 DCF channel access function allows single transmission inside two-hop network in order to avoid collisions and eliminate the hidden and exposed terminal problems. Singular transmission capability causes data frames waiting for the entire roundtrip time in the transmitter neighborhood, and results in increased frame latency and lower network throughput. Real-time and pervasive applications are severely affected for the lower medium utilization; especially with high network traffic. This work proposes a new scheme with the help of Frame Aggregation technique in IEEE802.11n and overcomes the single transmission barrier maintaining the basic DCF functionality. Proposed scheme allows parallel transmissions in non-interfering synchronized slots. Parallel transmissions bypass the conventional physical carrier sense and random Backoff time for several cases and reduce the frame latency and increase the medium utilization and network capacity.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.6
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• pp.61-72
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• 2014

We implemented ecological linkage assessment, through the connection components of the urban forests, rivers and parks, for the ecological connection of the urban parks which are standing out as the core of the urban green networks, so as to suggest basic data to compare, evaluate and improve urban green networks, as a basic study for the evaluation of the ecological connectabilities between the cities. For the ecological linkage assessment, we analyzed to see if the urban parks of Goyang, Ansan and Yongin, which are the subject cities, are actually ecologically connected with forests and rivers, using distance and roads, which are physical connection elements, in consideration of the mobility of the wild animals, and greening ratios and impervious pavement ratios, which are ecological connectabilities in consideration of the ecological values. The overall result of the ecological linkage assessment the physical connection elements and the ecological connection elements shows that the ecological green network ratio through direct connection states is 36.62% in Goyang, 42.55% in Ansan and 64.00% in Yongin, respectively, giving the ecological connectability ratio of less than half, with the average urban ecological green network ration of 47.72%. The comparison result of the ecological connectabilities between the object cities employing the connection elements indicates that when you set up green networks, you should consider together the physical connection elements, such as the roads, which will lower the ecological connectabilities - rather than do it simply based on areas and distances - while the ecological connection elements with the forests and the streams should be reinforced, so that the ecological connectabilities of the urban parks may be enhanced.

• Journal of the Economic Geographical Society of Korea
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• v.24 no.3
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• pp.243-258
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• 2021

By using the trade in value-added(TiVA) database and employing social network analysis, this paper analyzes changes in global trade to be triggered by the Belt and Road Initiative (BRI) and the US-China trade war. The main results are summarized as follows. First, the BRI will help maintain China's core position as the world's manufacturing hub, and will strengthen Europe's service industry capabilities within the global value chain(GVC) network. Second, the US R&D industry, US wholesale and retail industries, and Germany's automobile industry were considered the most influential industries in the GVC network during the 1995-2011 period, and will retain their status until 2049, when the US-China trade war and the BRI are reflected. Third, the increase of the number of communities shows that the BRI might spur fragmentation of the production process. Finally, community structures of inter-industry trade relations, including China's electronics industry, Germany's automobile industry, and US R&D, show important features that are related to the competiveness of each country's service industries.

• Annual Conference of KIPS
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• 2006.05a
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• pp.43-46
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• 2006

최근 센서네트워크에 관련된 많은 연구가 진행되고 있다. 특히, 센서의 전력 보전을 위한 많은 기술들이 개발되고 있는데, 본 논문에서는 센서 네트워크의 불필요한 전력 소비를 줄이는 다중 연속질의 최적화에 관련된 방법을 제시한다. 우리는 센서 네트워크에서 전송되는 데이터의 횟수나 전송량의 원천적 문제가 되는 다중 연속 질의의 중복성 문제를 해결하는 분할 알고리즘을 제안한다. 분할 알고리즘은 새롭게 생성된 사용자 질의와 기존의 질의 들 사이에 질의 중첩 질의 영역을 제거하기 위해, QR-트리 기반의 질의 인덱스를 통해 하나의 질의를 둘 이상의 질의로 분할하는 알고리즘이다. QR-트리는 효율적인 질의 분할을 위해, $R^*$-트리를 본 논문의 구조에 맞게 개량한 것이다.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.217-222
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• 2006

VANET은 인프라의 도움 없이 차량 간 무선 에드 혹 네트워크를 구축하는 기술이다. VANET은 MANET과는 달리 고속의 이동성, 높은 차량 밀도, 잦은 토폴로지 변화등의 특징으로 인해 잦은 네트워크 단절과 네트워크 부하 증가 등의 문제들을 가진다. 특히 네트워크 단절은 VANET에서 응급메세지 전파 시간 지연 및 네트워크 연결성 저하의 주요 요인이다. 본 논문에서는 이러한 네트워크 단절을 해결하기 위해 적응형 전달노드 검색(ARNS : Adaptive Relay Node Search) 브로드캐스팅 알고리즘을 제안한다. ARNS는 네트워크 단절 발생 시에만 선택적으로 위험지역 외의 영역에서 노드를 재 검색함으로 낮은 네트워크 부하와 낮은 네트워크 단절율을 가진다. 또한 ARNS은 짧은 전송거리와 낮은 차량밀도에도 네트워크 단절에 강한 특성을 지닌다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04b
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• pp.193-195
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• 2002

최근 근자상거래와 같은 웹 기반 응용프로그램에서는 높은 가용성과 확장성을 가지며 빠른 응답시간을 갖는 데이터베이스에 대한 필요성이 대두되고 있다. 이러한 요구에 대한 해결책의 하나로 비공유 구조의 클러스터 시스템을 구성하고 분활과 복제정책을 사용한다. 즉, 해쉬함수나 범위값에 의해 분할하여 여러 노드에 분산 시키고 서로 다른 노드에 마스터와 백업을 두어 가용성을 높이고 있다. 그러나 기존의 방법은 하나의 갱신 질의에 대해서 마스터와 백업에 각각 질의를 보내주어야 하고 온라인 확장시에는 모든 마스터와 백업의 데이터가 재구성되어야 하므로 네트워크 비용이 크다는 문제점이 있다. 따라서, 본 논문에서는 이러한 네트워크 비용을 줄이기 위한 변형된 분활 기법을 제안한다. 제안된 기법에서 마스터는 기존의 기법과 동일한 방법으로 저장하나 백업은 네트워크를 통해 지정된 노드로 포워딩을 하지 않고 질의를 받은 서버에 그대로 저장함으로써 클러스터를 구성하는 노드 사이에 통신 비용을 줄인다. 또한 온라인 확장에서는 기존의 기법과 달리 백업데이터는 같은 서버의 마스터데이터와 중복되는 것만 이동시킴으로써 데이터 이동비용을 줄이며, 전체 트랜잭션 처리량을 높인다.

• International Journal of Control, Automation, and Systems
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• v.3 no.1
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• pp.122-129
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• 2005

We describe the MiniWeb[7] TCP/IP stack (mIP), which is an extremely small implementation of the TCP/IP protocol suite running 8 or 32-bit micro controllers intended for embedded control systems, and satisfying the subset of RFC1122 requirements needed for host­to-host interoperability over different platforms. Our TCP/IP implementation does sacrifice some of TCP's mechanisms such as fragmentation, urgent data, retransmission, or congestion control. Our implementation is applicable to web based controllers. The network protocols are tested in operational networks using CommView and Dummynet where the various operational parameters such as bandwidth, delay, and queue sizes can be set and controlled.

• Journal of Communications and Networks
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• v.18 no.4
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• pp.658-669
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• 2016

The tremendous increase in mobile data traffic coupled with fierce competition in wireless industry brings about spectrum scarcity and bandwidth fragmentation. This inevitably results in asymmetric-valued long term evolution (LTE) spectrum allocation that stems from different timing for twice improvement in capacity between competing operators, given spectrum allocations today. This motivates us to study the economic effects of asymmetric-valued LTE spectrum allocation. In this paper, we formulate the interactions between operators and users as a hierarchical dynamic game framework, where two spiteful operators simultaneously make spectrum acquisition decisions in the upper-level first-price sealed-bid auction game, and dynamic pricing decisions in the lower-level differential game, taking into account user subscription dynamics. Using backward induction, we derive the equilibrium of the entire game under mild conditions. Through analytical and numerical results, we verify our studies by comparing the latest result of LTE spectrum auction in South Korea, which serves as the benchmark of asymmetric-valued LTE spectrum auction designs.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.7
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• pp.3533-3549
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• 2019

A big database utilizes the establishing network technology, and it became an emerging trend in the computing field. Therefore, there is a necessity for an optimal and effective data distribution approach to deal with this trend. This research presents the practical perspective of designing and implementing distributed database features. The proposed system has been establishing the satisfying, reliable, scalable, and standardized use of information. Furthermore, the proposed scheme reduces the vast and recurring efforts for designing an individual system for each university, as well as it is effectively participating in solving the course equivalence problem. The empirical finding in this study shows the superiority of the distributed system performance based on the average response time and the average waiting time than the centralized system. The system throughput also overcomes the centralized system because of data distribution and replication. Therefore, the analyzed data shows that the centralized system thrashes when the workload exceeds 60%, while the distributed system becomes thrashes after 81% workload.