• Proceedings of the Korea Society for Simulation Conference
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• 2005.11a
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• pp.108-112
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• 2005

유비쿼터스 컴퓨팅의 기반 설비인 센서 네트워크는 많은 수의 센서 노드들로 구성되며, 각 센서 노드의 하드웨어는 매우 작은 규모이다. 또한 센서 네트워크는 구축 목적에 따라 네트워크 토폴로지 및 라우팅 방식이 결정되어야 하고, 이와 더불어 센서 노드의 하드웨어와 소프트웨어도 필요에 따라 다양하게 변경되어야 한다. 따라서 센서 네트워크가 구현되기 전에 시스템 동작과 성능을 예측할 수 있는 센서 네트워크 시뮬레이터가 필요하다. 기존의 센서 네트워크 시뮬레이터들은 특별한 응용을 위한 특정 기반의 하드웨어와 운영체제에 국한되어 개발되었기 때문에 다양한 센서 네트워크 환경을 지원하기에는 한계가 있으며, 센서 네트워크 설계상의 주요 요소인 전력소모량과 실행 시간에 대한 분석이 포함되지 않았다. 따라서 본 연구에서는 특정한 응용이나 운영체제에 제한을 받지 않으면서 다양하게 센서 네트워크 환경을 설계 및 검증할 수 있고, 더불어 전력소모량과 실행시간 추정도 가능한 시뮬레이터를 개발하는 것을 목표로 하였다. 이를 위해 본 연구에서 개발한 시뮬레이터는 기계명령어-레벨(machine instruction-level)의 이산-사건 시뮬레이션(discrete-event simulation) 기법을 이용함으로써 실제 센서 노드의 프로그램 실행 및 관련 동작들을 세부적으로 예측하는 데 사용될 수 있도록 하였다. 시뮬레이션의 작업부하(workload)인 명령어 트레이스(instruction trace)로는 ATmega128L 마이크로컨트롤러용으로 크로스 컴파일된 인텔 핵스-레코드(.hex) 형식을 사용한다.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.6
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• pp.643-656
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• 2000

MPOA proposed and standardized by the ATM Forum is a protocol tllat provides effective bridging and routing for ATM networks in a diverse network environment. Its plimary goal is to transfer unicast data effectively among the subnets. In this paper, MPOA components are implemented using the SDL(Specification and Description Language) which the ITU has standardized for the development of communication systems. In addition, MPOA procedures for various operations such as address translation for packets from upper layers, Ingress/Egress cache management and shortcut configuration, are examined with tlle help of the SDT(SDL Design Too]) simulator.

• The KIPS Transactions:PartC
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• v.9C no.6
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• pp.945-952
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• 2002

For a successful inter-system handoff, several important issues must be handled and additional new features must be considered. This paper focuses on the cellular structure of small cells which are required for the high density of population and a handoff scheme designed between two heterogenous networks. Incase of inter-system handoff (ISHO), the time required to complete the handoff can vary and depends on the structure of networks. And also the transmission of additional signals can increase the probability of failure for ISHO. Here we propose the sub-boundary cell base station (Sub-BBS) to alleviate the role of the BBS. The Sub-BBS is adjacent to BBS in the same regional mobile network. 쪼en the mobile terminal enters Sub-BBS, the network starts finding a new route and after entering BBS, it initiates the transformation process. The proposed scheme significantly reduces the ISHO failure rate compared to the existing one which is the most recent and known as efficient.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.361-364
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• 2008

The Application Model in Wireless Sensor Networks(WSNs) consist of wireless sensor network based on sensor hardwares which is combined the micro-controller, chipset for wireless communication and sensors, middleware for dealing with data processing and user application for common service. Applications in WSN have been applied for environmental monitoring, smart factory and have concentrated the services based on remote monitoring applications which is difficult to watch the situation by human. In this paper, we described the construction model for applying for the Ubiquitous disaster prevention system and deal with its conformity. The proposed system includes the selecting the wireless sensor hardware, routing technique for u-Disaster Prevention, composition of middleware and web-interface for application services.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.4
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• pp.389-405
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• 1999

본 논문에서는 상호 연결망의 노드를 행렬로 표현하고 행렬연산을 이용하여 에지를 정의한 새로운 상호 연결망으로 행렬-스타 그래프를 제안한다. 행렬-스타 그래프는 널리 알려진 스타 그래프를 일반화한 그래프이다. 먼저, 행렬-스타 그래프의 노드를 2 $\times$ n 행렬로 표현한 행렬-스타 그래프 MS2,n 에 대하여 주요 망 척도인 분지수, 연결도, 확장성, 대칭성, 리우팅 ,지름 방송등을 분석한다. 다음으로, 행렬-스타 그래프 MS2,n의 노드를 2차원과 3차원으로 일반화한 행렬-스타 그래크 MSk,n과 MS k,n,p를 정의하고 행렬-스타그래프 MSk,n,p 의 라우팅 알고리즘과 지름을 분석한다. 상호연결망의 중요 망 척도중 하나는 망 비용이고 상호연결망의 망 비용은 그 연결망의 분지수와 지름의 곱으로 정의된다. star 그래프는 다른 상호 연결망보다 작은 망 비용을 갖는다. 최근에 제안된 Macro-Star 그래픈 star 그래프에 비해 상대적으로 망 비용이 작은 값을 갖는 연결망이다. (n2)!개의 노드를 갖는 행렬-스타 그래프 MSk,k,k(k={{{{ `^{ 3} SQRT { n$^2$} }}}} )와 ((n-1)2 + 1)!개의 노드를 갖는 Macro-Star 그래프 MS(n-1, n-1)의 망 비용은 행렬-스타그래프 MSk,k,k(k={{{{ `^{ 3} SQRT { n$^2$} }}}})는 O(n2,7)이고, Macro-Star 그래프 MS(n-1 , n-1)은 O(n3) 이다. 이는 행렬-스타 그래프가 스타 그래프와 Macro-Star 그래프보다 망비용이 우수함을 의미한다.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.8
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• pp.586-590
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• 2009

The objective of this paper describes the design of MapReduce over Peer-to-Peer network for dynamic environments applications. MapReduce is a software framework used for Cloud Computing which processing large data sets in a highly-parallel way. Based on the Peer-to-Peer network character which node failures will happen anytime, we focus on using a DHT routing protocol which named Pastry to handle the problem of node failures. Our results are very promising and indicate that the framework could have a wide application in P2P network systems while maintaining good computational efficiency and scalability. We believe that, P2P networks and parallel computing emerge as very hot research and development topics in industry and academia for many years to come.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.5
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• pp.429-432
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• 2004

In this paper, we propose a new sorting algorithm for ATM switch with a shared buffer which has a sequencer architecture with single queue. The proposed switch performs a sorting procedure of ATM cell based on the output port number of ATM cell with hardware implementation. The proposed architecture has a single buffer physically but logically it has function of multi-queue which is designed at most to control the conflicts in output port. In the future, this architecture will take various applications for routing switch and has flexibility for the extension of system structure. therefore, this structure is expected on good structure in effective transmission.

• Journal of IKEEE
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• v.23 no.2
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• pp.659-666
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• 2019

MANET can be applied to various applications as it can autonomously configure the network with only mobile nodes. However, the network can be vulnerable to cyber attacks because it is organized in a distributed environment without central control or management. In this paper, we propose a simulation-based network security vulnerability analysis and verification method. Using this method, we simulated the routing message modification attack, Sybil node attack, and TLV message modification attack that may frequently occur in MANET, and confirmed that similar vulnerabilities can be occurred in the real system. Therefore, the proposed method can be used to improve the accuracy of the protocol design by verifying possible security vulnerabilities through simulation during the protocol design procedure.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.125-128
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• 2022

As the number of online systems based on the internet gradually increases, cyber-scale attacks that interfere with the normal operation of web services are also on the rise. In particular, distributed denial-of-service attacks (DDoS) that interfere with normal web service operations are also increasing. Therefore, this paper presents an efficient DDoS attack defense technique utilizing Equal Cost Multi-Path (BGP ECMP) routing techniques in networks of Anycast type by operating PoP basis of major attack sources and describes how high-availability web services can be operated.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.2
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• pp.129-137
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• 2020

Currently, The autonomous vehicle market is researching and developing four-level autonomous vehicles beyond the commercialization of three-level autonomous vehicles. Because unlike the level 3, the level 4 autonomous vehicle has to deal with an emergency directly, the most important aspect of a four-level autonomous vehicle is its stability. In this paper, we propose an Optimized Vehicle Routing System (OVRS) that determines the route with the lowest probability of an accident at the destination of the vehicle rather than an immediate response in an emergency. The OVRS analyzes road and surrounding vehicle information collected by The RSU communication to predict road hazards, and sets the route for the safer and faster road. The OVRS can improve the stability of the vehicle by executing the route guidance according to the road situation through the RSU on the road like the network routing method. As a result, the RPNN of the ASICM, one of the OVRS modules, was about 17% better than the CNN and 40% better than the LSTM. However, because the study was conducted in a virtual environment using a PC, the possibility of accident of the VPDM was not actually verified. Therefore, in the future, experiments with high accuracy on VPDM due to the collection of accident data and actual roads should be conducted in real vehicles and RSUs.