• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.7
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• pp.845-851
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• 2019

We design, implement, and evaluate a user-level ad hoc network routing protocol on the COTS (commercial off-the-shelf) mobile devices. In situations such as disaster recovery, emergency communication between mobile devices is necessary. For wide deployability and usability of such a system, we design and implement the networking protocols on the user level instead of modifying the kernel of mobile devices. In order to support reliable data transfer in high mobility scenarios, we selected to implement AODV (Ad Hoc On-Demand Distance Vector) as the routing protocol and TCP as the transport layer protocol. With our implementation of ad hoc networking stack on COTS smartphones, we conducted experiments in various networking environments. Our experimental results show that ad hoc networking is possible in up to 12 hops in a line topology and 5 concurrent devices in a star topology.

• Journal of Communications and Networks
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• v.9 no.3
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• pp.296-311
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• 2007

Mobile multi-robot teams are useful in many critical applications such as search and rescue. Explicit communication among robots in such mobile multi-robot teams is useful for the coordination of such teams as well as exchanging data. Since many applications for mobile robots involve scenarios in which communication infrastructure may be damaged or unavailable, mobile robot teams frequently need to communicate with each other via ad hoc networking. In such scenarios, low-overhead and energy-efficient routing protocols for delivering messages among robots are a key requirement. Two important primitives for communication are essential for enabling a wide variety of mobile robot applications. First, unicast communication (between two robots) needs to be provided to enable coordination and data exchange. Second, in many applications, group communication is required for flexible control, organization, and management of the mobile robots. Multicast provides a bandwidth-efficient communication method between a source and a group of robots. In this paper, we first propose and evaluate two unicast routing protocols tailored for use in ad hoc networks formed by mobile multi-robot teams: Mobile robot distance vector (MRDV) and mobile robot source routing (MRSR). Both protocols exploit the unique mobility characteristics of mobile robot networks to perform efficient routing. Our simulation study show that both MRDV and MRSR incur lower overhead while operating in mobile robot networks when compared to traditional mobile ad hoc network routing protocols such as DSR and AODV. We then propose and evaluate an efficient multicast protocol mobile robot mesh multicast (MRMM) for deployment in mobile robot networks. MRMM exploits the fact that mobile robots know what velocity they are instructed to move at and for what distance in building a long lifetime sparse mesh for group communication that is more efficient. Our results show that MRMM provides an efficient group communication mechanism that can potentially be used in many mobile robot application scenarios.

• Korean Institute of Interior Design Journal
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• no.28
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• pp.44-50
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• 2001

This study propose the new concept of residence by analyzing the change of residence through the characteristic of popularity and degree of development of technology on home network information appliance for intelligent home. Accordingly, Cyber village represented as home automation and extend to information of society. it encourage need of information and multimedia of home. It expect home information infrastructure for accepting informations, which make smart home to linked home-working home-learning home-treatment. home-shopping and home-banking. The system of intelligent home is the intelligence of human-biology in the side of environmental friendly and multi-function. it distinguish the system of security, controlling system of inside environment, supporting system of house-working, automatic controlling, house working. Future house require to meet demand of young generation, such as small residental space, the multi-functional space, the flexible space, making mood for dual income couple and of single as intelligent home. Accordingly, basic purpose which are pleasantness, the safe and the convenience the mobile multi-function as well as networking with controlling of temperature, security, health-test, home-entertainment, home-office and consider environment together.

• ETRI Journal
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• v.37 no.2
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• pp.369-379
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• 2015

Fault management of virtualized network environments using user-driven network provisioning systems (NPSs) is crucial for guaranteeing seamless virtual network services irrespective of physical infrastructure impairment. The network service interface (NSI) of the Open Grid Forum reflects the need for a common standard management API for the reservation and provisioning of user-driven virtual circuits (VCs) across global networks. NSI-based NPSs (that is, network service agents) can be used to compose user-driven VCs for mission-critical applications in a dynamic multi-domain. In this article, we first attempt to outline the design issues and challenges faced when attempting to provide mission-critical applications using dynamic VCs with a protection that is both user-driven and trustworthy in a dynamic multi-domain environment, to motivate work in this area of research. We also survey representative works that address inter-domain VC protection and qualitatively evaluate them and current NSI against the issues and challenges.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.230-232
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• 2010

최근 무선 멀티 인터페이스를 이용한 동시 접속 기술에 관한 연구가 활발히 진행 중이다. 이와 관련된 연구 중 하나인 Proxy MIPv6 환경에서 멀티호밍 지원에 관한 연구가 IETF Netext WG에서 진행 중이다. 기존 Proxy MIPv6 프로토콜은 멀티인터페이스 제공 시 독립된 HNP 할당을 통해 동시 접속 서비스를 제공하고 있다. 하지만 이 방법은 이동 노드의 세션 연결성을 유지하지 못하는 문제점을 가지고 있다. 본 논문에서는 이런 문제점을 해결하기 위해 멀티호밍 되어 있는 이동 단말 내부에 가상 인터페이스 모델의 필요성과 기능에 대해서 정의하며 또한 가상 인터페이스를 통해 기존 연결성을 유지 할 수 있도록 방법을 제안하고 이에 관해 논한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.485-487
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• 2009

최근 무선 멀티 인터페이스를 이용한 동시 접속 기술에 관한 연구가 활발히 진행 중이다. 이와 관련된 연구로 IETF Netext WG에서 Proxy Mobile IPv6 (PMIPv6) 기반 멀티인터페이스 지원 기술에 대해서 표준 기술이 논의 중에 있으며 IETF MIF(Multiple InterFace) WG에서도 멀티인터페이스 노드 관점와 네트워크 관점에서 멀티 네트워크 인터페이스 지원 시 발생하는 문제점을 정의하고 이를 해결하기 위한 기존 기술 분석을 진행 중이다. 본 논문에서는 Proxy MIPv6 도메인에서 멀티 호밍 지원 기술을 가진 Proxy MIPv6 프로토콜을 이용한 멀티인터페이스 동시접속과 인터페이스 사이의 inter handoff 지원 기술 시 발생하는 문제점들을 정의하고 가능한 해결 시나리오에 대해서 논의한다.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.8
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• pp.261-270
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• 2014

As Internet traffic increases recently, much effort has been put on improving the performance of a web server. In addition to hardware side solutions such as replacement by high-end hardware or expansion of the number of servers, there are software side solutions to improve performance. Recent studies on these software side solutions have been actively performed. In this paper, we identify performance degradation problems occurring in a conventional TCP networking reception process and propose a way to solve them. We improve performance by combining three kinds of existing methods for Linux Networking Performance Improvement and two kinds of newly proposed methods in this paper. The three existing methods include 1) an allocation method of a packet flow to a core in a multi-core environment, 2) ITR(Interrupt Throttle Rate) method to control excessive interrupt requests, and 3) sk_buff data structure recycling. The two newly proposed methods are fd data structure recycling and epoll_event data structure recycling. Through experiments in a web server environment, we verify the effect of our two proposed methods and its combination with the three existing methods for performance improvement, respectively. We use three kinds of web servers: a simple web server, Lighttpd generally used in Linux, and Apache. In a simple web server environment, fd data structure recycling and epoll_event data structure recycling bring out performance improvement by about 7 % and 6%, respectively. If they are combined with the three existing methods, performance is improved by up to 40% in total. In a Lighttpd and an Apache web server environment, the combination of five methods brings out performance improvement by up to 36% and 20% in total, respectively.

• Journal of KIISE:Information Networking
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• v.37 no.5
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• pp.374-385
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• 2010

Wireless mesh networks can be deployed for various networks from home networking to last-mile broadband Internet access. Wireless mesh networks are composed of mesh routers and mesh clients. In these networks, static nodes form a multi-hop backbone of a large wireless access network that provides connectivity to end-users' mobile terminals. The network nodes cooperate with each other to relay data traffic to its destinations. In order to increase connectivity and better performance, researchers are getting interested in multi-channel and multi-interface wireless mesh networks. In these networks, non-overlapping multiple frequency channels are used simultaneously to increase the aggregate bandwidth available to end-users. Recently, researches have focused on finding suitable channel assignments for wireless network interfaces, equiped in a mesh node, together with efficient routing to improve overall system throughput in wireless mesh networks. This goal can be achieved by minimize channel interference. Less interference among using channels in a network guarantees more aggregated channel capacity and better connectivity of the networks. In this thesis, we propose interference aware channel assignment and routing algorithms for multi-channel multi-hop wireless mesh networks. We propose Channel Assignment and Routing algorithms using Traffic Profiles(CARTP) and Routing algorithms allowing detour routing(CARTP+2). Finally, we evaluate the performance of proposed algorithms in comparison to results from previous methods using ns-2 simulations. The simulation results show that our proposed algorithms can enhance the overall network performance in wireless mesh networks.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.111-113
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• 2013

멀티 코어 시스템의 보급으로 일반 시스템에서도 프로그램의 병렬 실행이 가능해지고 있다. 본 연구에서는 멀티 코어를 사용하는 단일 시스템에서 분자 동역학 코드인 LAMMPS를 대상으로 병렬 수행 성능을 확인하고 분석하여 효과적인 실행 조건을 살펴보았다. LAMMPS의 구조적인 특징과 공간 분할 방식의 사용으로 인하여 단일 시스템에서도 메시지 전달 방식에 의한 병렬 수행이 보다 효율적임을 확인할 수 있었다.

• Journal of KIISE:Information Networking
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• v.34 no.1
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• pp.27-32
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• 2007

Next-generation wireless networks are expected to support a wide range of services, including high-rate data applications, Various service types request differentiated QoSs(Qualities of Service) such as minimum data rate, accuracy, fairness and so on. Although resources of radio systems are limited, for many applications, it is important that certain QoS targets are required to be met. In this paper, we propose a QoS based scheduling algorithm for next generation systems, based on analyzing previous researches, and we develop the proposed QoS algorithm only for MIMO(multi-Input Multi-Output) systems. Moreover, we subsequently prove that the proposed algorithm optimize throughput relative to prespecified target values and converge to certain throughput.