• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.211-217
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• 2008

Recently, there are many efforts to support seamless mobility in 802.11 WLANs using IP Layer mobility protocols. The IP layer mobility protocols are the most efficient mechanism to guarantee the service session continuity when IP subnet is changed during handover. Even if the IP layer mobility protocols are quite efficient, the feature of the protocols that had been designed to consider only L3 layer makes it difficult to improve the performance of hand over more and more. Nowadays, to overcome this limitation of IP mobility protocols, many researchers have worked on the mobility protocols integration of different layers (e.g., L2 layer). In this paper, we propose the enhanced Proxy MIPv4 to minimize the latency of handover using MIH protocol in 802.11 WLANs. The proposed mechanism minimizes the latency of authentication by exchanging security keys between Access Routers during handover. Moreover, it also minimizes packet losses by Inter-AP Tunneling and data forwarding.

• Journal of KIISE:Information Networking
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• v.29 no.4
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• pp.428-436
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• 2002

Providing a mobile host with its required QoS is highly influenced by its mobility. The resource ReSerVation Protocol(RSVP) establishes and maintains a reservation state to ensure a given QoS level along the path from the sender to the receiver. However, RSVP is designed for use in fixed networks and thus it is inadequate in the mobile networking environment where a host changes its point of attachment. In this paper, we propose a new resource reservation protocol, RSVP-RA(RSVP by RSVP Agent) for mobile hosts. Our protocol assumes IETF Mobile IP as a mobility support mechanism. The proposed protocol introduce a new protocol entity - RSVP agent - to manage reservations in a mobile host's current visiting network. RSVP Agent is located in a local network and makes resource reservations in neighboring cells that the mobile host is expected to visit in the future. Thus, the proposed Protocol can provide a seamless QoS to the mobile host and significantly improve the scalability problem of RSVP by reducing the end-to-end signalling messages acrossing the backbone networks. The proposed protocols reduce packet delay, bandwidth overhead and the number of RSVP messages to maintain reservation states. We compared the performance of our proposed protocol with other proposed protocols in terms of signalling overhead, packet delay by simulation.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.2
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• pp.176-183
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• 2014

Acoustic emission testing (AET) of cylinders is advantageous in that it can be directly conducted on cylinders installed in a car, without needing to dissemble them on a real-time basis. Therefore, users prefer AET over other nondestructive testing methods. Owing to these advantages of AET, it has been approved by the Department of Transportation of the U.S. as a safety evaluation method for pressure containers or as an alternative to the hydroproof testing method. This paper presents a study of the quantitative evaluation criteria for a container having ultrasonic testing defects and also for Type 1 and Type 2 gas cylinders, which are defective seamless pressure containers provided by NK, a manufacturer of pressure containers. For the Type 1 cylinder, the process from crack growth to leak was observed in a repetitive fatigue test using a 113 L container according to ASTM E 1419-02. Further, for the Type 2 cylinder, integrity was evaluated using a 119 L sound container and a container damaged by hydraulic pressure, by the slow-fill method according to ASTM E 2191-02. Based on the AET results of the Type 1 and Type 2 cylinders, quantitative evaluation criteria were established for a defective and non-defective container.

• Journal of Internet Computing and Services
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• v.10 no.2
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• pp.171-177
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• 2009

Optical packet switching(OPS) is a strong candidate for the next-generation internet, since it has a fine switching granularity at the packet level for providing flexible bandwidth, and provides seamless integration between WDM layer and IP layer. Optical packet switching have been studied in two categories: OPS in synchronous and OPS in asynchronous networks. In this article we are focused on contention resolution of OPS in asynchronous networks. The hybrid buffer have been addressed, to reduce packet loss further as one of the alternative buffer structures for contention resolution of asynchronous and variable length packets, which consists of the FDL buffer and the electronic buffer. The OPS design issue for the limited number of TWCs and internal wavelengths is important in the aspect of switch cost and resource efficiency. Therefore, an hybrid buffer structured optical packet switch and its scheduling algorithm is presented for considering the limited number of TWCs and internal wavelengths, for contention resolution of asynchronous and variable length packets. The proposed algorithm could lead to the packet loss improvement compared to the legacy LAUC-VF algorithm with only the FDL buffer.

• Journal of Internet Computing and Services
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• v.17 no.6
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• pp.1-8
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• 2016

Current indoor intrusion detection and location tracking methods have the weakness in seamless operations in tracking the objective because the object must possess a communicating device and the limitation of the single cell size (approximate $100cm{\times}100cm$) exits. Also, the utilization of CCTV technologies show the shortcomings in tracking when the object disappear the area where the CCTV is not installed or illumination is not enough for capturing the scene (e.g. where the context-awarded system is not installed or low illumination presents). Therefore, in this paper we present an improved in-door tracking system based on sensor networks. Such system is built on a simulated scenario and enables us to detect and extend the area of surveillance as well as actively responding the emergency situation. Through simulated studies, we have demonstrated that the proposed system is capable of supplementing the shortcomings of signal cutting, and of estimating the location of the moving object. We expect the study will improve the better analysis of the intruder behavior, the more effective prevention and flexible response to various emergency situations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.694-699
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• 2017

In accordance with the development of information and communications technology, a network user has to be able to use quality of service (QoS)-based multimedia services easily. Thus, information and communications operators began to focus on a technique for providing multimedia services. The IP Multimedia Subsystem (IMS) is a platform based on Internet Protocol (IP) as a technology for providing multimedia services and application services. The emerging 5G networks are described as having massive capacity and connectivity, adaptability, seamless heterogeneity, and great flexibility. The explosive growth in network services and devices for 5G will cause excessive traffic loads. In this paper, software-defined networking (SDN) is applied as a kind of virtualization technology for the network in order to minimize the traffic load, and Simple Network Management Protocol (SNMP) is used to provide more efficient network management. To accomplish these purposes, we suggest the design of a dynamic routing algorithm to be utilized in the IMS network using SDN and an SNMP private management information base (MIB). The proposal in this paper gives information and communications operators the ability to supply more efficient network resources.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.191-200
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• 2017

Smart work is an alternative form to enable seamless business collaboration without time and space limitations using ICT. However, smart work implementation has not produced tangible achievements and sometimes has resulted in failure. This study examined users' resistance against smart work, which is regarded as one of the most important elements for the successful implementation of smart work. The study classified elements which cause users' resistance into the work's innovative characteristics and the user characteristics based on the model of innovation resistance. It also set the degree of freedom in spatial and temporal dimension as moderating factors. This empirical research results showed that low work efficiency, unfavorable evaluation methods, and high degree of satisfaction in the way of working affected smart work users' resistance. In addition, temporal freedom had a moderating effect on the relationship between users' characteristics and their resistance. On the contrary, spatial freedom affected the relationship between their works' innovative characteristics and their resistance. The study results suggest that organizations need to set up business processes and evaluation methods first to adopt Smart work successfully.

• Journal of KIISE:Software and Applications
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• v.33 no.6
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• pp.550-563
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• 2006

Software product line engineering is a method that prepares for the future reuse and supports to seamless reuse in application development process. Commonality and variability play central roles in all product line development processes. Reusable assets will become core assets by explicitly representing C&V. Indeed, the variabilities that art identified at each phase of core assets development have different levels of abstraction. In the past, these variabilities have been handled in an implicit manner and without distinguishing the characteristics of each core assets. In addition, previous approaches have depended on the experience and intuition of a domain expert to recognize commonality and variability. In this paper, we suggest a 2-dimensional analyzing method that analyzes the variabilities of core assets in software product line. In horizontal analysis process, the variation types are analyzed in requirements, architecture, and component that are produced at each phase of development process. In vertical analysis process, variations are analyzed in different abstract levels, in which the region of commonality is identified and the variation points are refined. By this method, the traceability of variations between core assets will be possible and core assets can be reused seamlessly.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.11
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• pp.1966-1975
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• 2008

NEMO Basic Support Protocol standardized in IETF provides the seamless communication environment to all nodes within the mobile network regardless of the network movement while the network is moving. According to the standard, when the mobile network moves outside of its home network the network can make use of the binding update message or dynamic routing protocol in order to register the mobility information into the Home Agent(HA). But because these two methods don't consider the route optimization, all packets destined to Mobile Network Nodes(MNNs) attached into the Mobile Router(MR) have to go through HAs of MRs so that they bring on the transmission delay and the waste of the bandwidth. This situation is to be worse and causes the packet fragmentation problem if MRs within the mobile network are nested. Even though there have been some researches about the route optimization to recover the problems, they have problems in the packet transmission performance side. In this paper, we propose a new scheme to improve the network performance by using a dynamic routing protocol and minimizing the number of HAs on the end-to-end path. Various performance evaluations show that the proposed mechanism gives better performance in view of the packet transmission compared to the existing schemes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.754-762
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• 2021

Seamless wireless communication network access technology enables users to guarantee service continuity. Hence, it is necessary for disaster situations in which network service may be interrupted. The Multi-path router is a technology to improve network stability and strengthen field operability, particularly in a disaster environment where network failure can occur by providing high-performance data transmission using multi-communication networks and network security by VPN-based wireless IP. In this paper, a prototype system for an MPR-based wireless communication network was proposed to improve the operation performance for disaster field investigation applications. A comparative experiment was performed on various data transmission performances with the existing single wireless communication network. In addition, another experiment was conducted by measuring the data packet transmission and receiving performance in the existing/new wireless communication system first and then assessing the UDP transmission performance in a single router environment to understand the transmission capability of the new MPR. The experimental results showed that the sending and receiving performance was improved by approximately double that of the existing single wireless communication system. The proposed prototype system is expected to allow users to share and disseminate collected on-site data more quickly and efficiently during a disaster site investigation.