• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.459-461
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• 2010

Ad-Hoc VoIP system is an important IP phone technique used in MANET networks. In small-scale networks, VoIP system could be built easily while keeping the Qos on a acceptable level. Although Ad-Hoc VoIP system is designed as 'Client-Server' model, due to the property of MANETs that no Base Stations working as servers, we have the SIP Server with promary funtions worked on mobile terminals instead. In this paper, we explored how to build VoIP systems in MANETs and achieved the construction from within linux.

• Journal of Internet Computing and Services
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• v.14 no.5
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• pp.11-26
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• 2013

In the wireless Internet, it is so restrictive to use the IPSec. The MIPv4 IPSec's path cannot include wireless links. That is, the IPSec of the wireless Internet cannot protect an entire path of Host-to-Host connection. Also wireless circumstance keeps a path static during the shorter time, nevertheless, the IKE for IPSec SA agreement requires relatively long delay. The certificate management of IPSec PKI security needs too much burden. This means that IPSec of the wireless Internet is so disadvantageous. Our paper is to construct the Mobile IPSec proper to the wireless Internet which provides the host-to-host transport mode service to protect even wireless links as applying excellent WP-IBE scheme. For this, Mobile IPSec requires a dynamic routing over a path with wireless links. FA Forwarding is a routing method for FA to extend the path to a newly formed wireless link. The FA IPSec SA for FA Forwarding is updated to comply the dynamically extended path using Source Routing based Bind Update. To improve the performance of IPSec, we apply efficient and strong future Identity based Weil Pairing Bilinear Elliptic Curve Cryptography called as WP-IBE scheme. Our paper proposes the modified protocols to apply 6 security-related algorithms of WP-IBE into the Mobile IPSec. Particularly we focus on the protocols to be applied to construct ESP Datagram.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.1
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• pp.7-14
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• 2014

The rapid increase of mobile devices such as smart phone and smart pad have raised the needs for seamless multimedia services during moving at anytime and anywhere. Current 4G mobile devices are equipped with both 4G (LTE) and WLAN (WiFi) interfaces, and mobile services operators provide wireless Internet services using 4G network with a wider coverage and WiFi zone. Generally users prefer to use the Internet services through WLAN rather than LTE in the coverage of WLAN. However, since WLAN has a long L2 handover latency, it is difficult to support seamless services during a handover. In this paper, we proposed an efficient handover scheme based on flow mobility for WLANs to support a seamless service during handovers by using the overlaid 4G network with a wider coverage. Also, we showed the outperformance of the proposed scheme on a testbed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.4
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• pp.131-140
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• 2011

Proxy Mobile IPv6 (PMIPv6) is designed to provide a network-based localized mobility management protocol, but it does not handle the global mobility of hosts. In this paper, we propose a location management scheme based on Domain Name System (DNS) for PMIPv6. In this proposed scheme, DNS as a location manager provides PMIPv6 for global mobility. In addition, a paging extension scheme is introduced to PMIPv6 in order to support large numbers of mobile terminals and enhance network scalability. To evaluate the proposed location management scheme, we establish an analytical model, formulate the location update and the paging cost, and analyse the influence of the different factors on the total signalling cost. The performance results show how the total signal cost changes under various parameters.

• Journal of KIISE:Information Networking
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• v.34 no.5
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• pp.348-359
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• 2007

The conventional mobile VPN services assumed the mobile communications occur between the MN in foreign networks and the CN in the home network. However, if a MN wants to communicate with another MN in a foreign network, it could degrade the performance of the mobile VPN service because of the triangular routing problem. In this paper, we propose a route optimization mechanism based on the mobile VPN using an x-HA allocated by diameter MIP in order to support the efficient communication between the mobile VPN users in foreign networks. The i-HA maintains the VPN-TIA as well as the x-HoA as the CoAs to solve the security problem and to provide an efficient route optimization simultaneously. Moreover, we proposed revised IPSec tunnel configuration to reduce the IPSec tunnel overheads at a MN when the MN communicates with several MNs in the foreign networks at the same time. The VPN server, a security management entity in the home network, notifies an additional IPSec tunnel establishment between the x-HAs where the communication peers are registered. The simulation result showed that the proposed scheme decreases the end-to-end packet delay time and improves the throughput after the handoff compared to the existing mechanism.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.4
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• pp.677-685
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• 2012

Recently, wireless multi-networking technology has been studied for supporting multi-interface in mobile node. As the related work, in the IETF NetExt WG, the extension of Proxy Mobile IPv6 protocol for supporting flow mobility is actively on going in discussion. PMIPv6 protocol supports simultaneous access through the multi-interface in a mobile node and inter-technology handover between multiple interfaces. However, this protocol can not support flow mobility. Thus, in this paper, when a mobile node connects to PMIPv6 domain through multi-interface, as a way to support flow mobility, the design of logical interface and Home Network Prefix change scheme based on logical interface are proposed, We show that the proposed scheme can perform flow mobility service without end-to-end disconnection in PMIPv6 domain.

• International Commerce and Information Review
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• v.18 no.2
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• pp.27-51
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• 2016

The purpose of this paper is to examine correlations between the facilitating factors of the B2C e-commerce and the online shopping and the overseas direct purchase for the purpose of suggesting the successful logistics operational strategies for the domestic parcel delivery service companies. This paper conducts wide literature reviews and empirical analyses on relationships between the facilitating factors of B2C e-commerce and the online shopping and the overseas direct purchase in B2C e-commerce. We built two regression equations that dependable variables are the turnover of online shopping and the amount of imports by international postal logistics services respectively. The former equation's estimation results show that all the independable variables are affecting the dependable variable in the long-term jointly. And, the results show that the change of the turnover of online shopping is affected not only by the change of the usage count of a credit card and the real GDP, but also by the change of the error-correction variable. The latter equation's estimation results show that all the independable variables are affecting the dependable variable in the long-term jointly. Futhermore, the results show that the change of the amount of imports by international postal logistics services is affected not only by the change of the usage count of a credit card, the exchange rate and the internet protocol IPv4, but also by the change of the error-correction variable. Based on these research results, a high advanced strategic approach for optimum parcel delivery services is highly required.

• Journal of Advanced Navigation Technology
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• v.14 no.4
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• pp.537-544
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• 2010

The PMIPv6 is a network controlled mobility management protocol in which mobile nodes never participate in IP mobility protocol signaling. One issue in using PMIPv6 for multicast service is that a new component should be added as the mobility management functions are located not on the device but on the network. Currently, standardization activities for providing muticast services with PMIPv6 have been actively in progress. This paper addresses some issues about the on-going standardization works for providing efficient real-time multicast services with PMIPv6, and proposes a scheme for minimizing hand over delays and packet losses by using a new neighbor cell reporting method. The proposed scheme has been verified to outperform the existing scheme in hand over delay and packet loss perfonnrmces by using computer simulations.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2006.06a
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• pp.46-66
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• 2006

새로운 지능기반사회(ubiquitous society) 패러다임이란 전제 아래 미국을 비롯해 일본, 유럽 등 세계 각국에서는 모바일, 브로드밴드, 극소형 컴퓨터, IPv6의 기술이 창출해 내는 컴퓨팅 혁명의 실체를 유비궈터스 IT로 파악하고 각 국의 걸부, 기업, 연구소들이 주도권을 잡기 위해 많은 노력을 기울이고 있다. 현재 유비쿼터스 IT를 활용한 u-비즈니스를 활성화하고 관련 시장을 선점하기 위한 전 세계적인 경쟁은 매우 치열한 양상을 보이고 있다. 주요 국가들은 서로 지향하는 영역은 다르지만 궁극적으로 지능기반사회 구현이라는 대명제 아래 독자적인 산업 구축을 위해 노력하고 있다. 이러한 이유는 기본적으로 지능기반사회로의 이행과정에서 발생하는 경제적 파급효과, 예컨대 디지털 가전, 이동통신기기, 전자의료기기, 디스플레이, 2차 전지, 보안 등 관련 산업에 미치는 영향 및 새로운 시장 창출의 기회가 있기 때문이다. 기존의 많은 연구 및 문헌에서는 아직도 유비쿼터스 IT에 대한 개념적인 논의에 치중되어 있고 시장 중심적 또는 수요자 중심적 사고의 논의가 부족하다. 성공적으로 유비쿼터스 산업을 육성하기 위해서는 유비쿼터스 IT자체기술 개발사업(tangible service) 뿐만 아니라 비가시적(intangible) 서비스, 그리고 컨버전스(convergence) 서비스에 대한 상용화 모델과 성공적 사업 전개 방법론에 대한 깊은 연구가 수행되어야 한다. 본 연구에서는 먼저 유비쿼터스 IT의 기술동향과 시장 동향 및 산업 규모에 대한 문헌연구를 통해 u-비즈니스의 가능성을 고찰해보고, u-비즈니스 추진 전략을 탐색적으로 제시하고자 한다.되었다. SPME-GC/MS에 의한 휘발성분 분석 결과, 기능성 유지에서 홍국쌀 에탄올 추출물로부터 기인되는 특유의 휘발성분은 관찰되지 않았으나, RT=12.1 min인 hexanal의 함량이 control에 비하여 유의적인 감소 경향을 나타내는 것이 확인되었다(p<0.05).히지 못하여, 이의 기전을 밝히기 위한 추후 연구가 필요하다./TEX>로서 p<0.01 수준에서 현저히 증가하였다. 혈청의 인지질과 콜레스테롤 에스테르의 지방산 조성에서 vitamin C를 혼합 투여한 3,5,7군에서 PUFA 함량이 증가한 반면, SFA 함량은 감소하여 P/S 비율, n-3P/n-6P 비율은 증가하는 경향이었으며 이는 간장의 인지질, 콜레스테롤 에스테르, 총 지질의 지방산조성에서도 같은 경향을 볼 수 있었다.X>$(C_{18:2})$와 n-3계 linolenic acid$(C_{18:3})$가 대부분을 차지하였다. 야생 돌복숭아 과육 중의 지방산 조성은 포화지방산이 16.74%, 단불포화지방산 17.51% 및 다불포화지방산이 65.73%의 함유 비율을 보였는데, 이 중 다불포화지방산인 n-6계 linoleic acid$(C_{18:2})$와 n-3계 linolenic acid$(C_{18:3})$가 지질 구성 총 지방산의 대부분을 차지하는 함유 비율을 나타내었다.했다. 하강하는 약 4일간의 기상변화가 자발성 기흉 발생에 영향을 미친다고 추론할 수 있었다. 향후 본 연구에서 추론된 기상변화와 기흉 발생과의 인과관계를 확인하고 좀 더 구체화하기 위한 연구가 필요할 것이다.게 이루어질 수 있을 것