• The KIPS Transactions:PartC
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• v.12C no.2 s.98
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• pp.157-168
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• 2005

Group key agreement protocols are designed to provide a group of parties securely communicating over a public network with a session key. The mobile computing architecture is asymmetric in the sense of computational capabilities of participants. That is, the protocol participants consist of the stationary server(application servers) with sufficient computational Power and a cluster of mobile devices(clients) with limited computational resources. It is desirable to minimize the amount of computation performed by each group member in a group involving low-power mobile devices such as smart cards or personal digital assistants(PDAs). Furthermore we are required to update the group key with low computational costs when the members need to be excluded from the group or multiple new members need to be brought into an existing group. In this paper, we propose a dynamic group key protocol which offers computational efficiency to the clients with low-power mobile devices. We compare the total communicative and computational costs of our protocol with others and prove its suity against a passive adversary in the random oracle model.

• Journal of Internet Computing and Services
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• v.4 no.4
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• pp.53-64
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• 2003

To perform the certificate validation on the user-side application induces the very considerable overhead on the user-side system because of the complex and time-consuming characteristic of the validation processing. Most of the time spend for performing the validation processing is required for the digital signature verification, since the verification accompanies with the cryptographic calculation over each certificate on the certificate path. In this paper, we propose a new certificate validation scheme using DSVP(Delegated Signature Validation Protocol) which can reduce the overhead for the user-side certificate validation processing. It is achieved by delegating the digital signature verification to CAs of the PKI domain. As the proposed DSVP is the protocol performed between a user and CAs, it is applied to the hierarchical PKI efficiently and used for delegating the digital signature verification reliably and safely, our proposed scheme can not only reduces the overhead for the validation processing by decreasing the cryptographic calculation but also improves the utilization of CAs by employing them to the validation processing.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.05b
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• pp.628-634
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• 2003

In existing internet, e-mail protocols including POP3 and IMAP4, provide e-mail services for exchanging messages with texts, hypertext and images as well. For the e-mail services in wireless mobile network, mobile e-mail service Providers have to install a mobile exclusive e-mail server or have to convert e-mail to mobile exclusive e-mail with wireless application format in case of POP3 protocol. In the e-mail service of IMAP4 case known as web-mail, It is difficult to view e-mail directly from server without IMAP4 mobile client because e-mail is stored in mail server side with remote file server. In either case, it also has the problems of viewing the e-mail of hypertext and image information at mobile, This Paper Provides e-mail extraction engine with image and hypertext conversion facilities that can be applied in wireless mobile internet and it is optimized In mobile communication environments such as a small display, small size of memory with web-mail protocol based on IMAP4 as well as POP3 mail protocol.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.11
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• pp.5179-5202
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• 2018

Transmission Control Protocol (TCP) is the most widely used protocol in the cloud data centers today. However, cloud data centers using TCP experience many issues as TCP was designed based on the assumption that it would primarily be used in Wide Area Networks (WANs). One of the major issues with TCP in the cloud data centers is the Incast issue. This issue arises because of the many-to-one communication pattern that commonly exists in the modern cloud data centers. In many-to-one communication pattern, multiple senders simultaneously send data to a single receiver. This causes packet loss at the switch buffer which results in TCP throughput collapse that leads to high Flow Completion Time (FCT). Recently, Software-Defined Networking (SDN) has been used by many researchers to mitigate the Incast issue. In this paper, a detailed survey of various SDN based solutions to the Incast issue is carried out. In this survey, various SDN based solutions are classified into four categories i.e. TCP Receive Window based solutions, Tuning TCP Parameters based solutions, Quick Recovery based solutions and Application Layer based solutions. All the solutions are critically evaluated in terms of their principles, advantages, and shortcomings. Another important feature of this survey is to compare various SDN based solutions with respect to different performance metrics e.g. maximum number of concurrent senders supported, calculation of delay at the controller etc. These performance metrics are important for deployment of any SDN based solution in modern cloud data centers. In addition, future research directions are also discussed in this survey that can be explored to design and develop better SDN based solutions to the Incast issue.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.3
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• pp.109-120
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• 2008

VoIP utilizes the Internet for the services, and therefore it is vulnerable to intrusions and attacks. Because provided services deal with information related to privacy of users, it requires high level security including authentication and the confidentiality/integrity of signaling messages and media streams. However, when such a protocol is implemented in a VoIP phone, the implementation can have limitations due to the limited resources. The present study purposed to implement VoIP security protocols and to evaluate their performance in terms of connection quality and voice quality by applying them to SIP proxy and UA (User Agent). In the result of performance evaluation, the application of the security protocols did not lower voice quality, but connection quality was high in the DTLS based security protocol. As the protocol was applicable to signaling and media paths based on DTLS, we found that it can be a solution for the limited resources of VoIP phone.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.5
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• pp.45-57
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• 2009

In this paper, we implemented the conference system based on DTLS for saving securely the VoIP, which is served sprightly in the latest, securely and tested (and also analyzed) the system. As VoIP technology development, demand of conference system is increased and the related technologies are growed. But Security protocol to protect conference service is getting late than conference technology. In this paper, we studied based on DTLS protocol that can provide function of signaling, channel security, media channel security and application of group key and apply to VoIP conference system based UDP unchanged. In this paper, we searched suggested security protocols based on DTLS can apply to conference system and implement and apply the protocol to conference system. And we tested (and also alayzed) overhead of encryption and key management mechanism.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.10
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• pp.1432-1440
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• 2022

Recently, as Virtual Desktop Infrastructure(VDI) is widely used not only in office work environments but also in workloads that use high-spec multi-core-based applications, the requirements for real-time and stability of VDI are increasing. Accordingly, the display protocol used for remote access in VDI and performance optimization of virtual machines have also become more important. In this paper, we propose two ways to configure desktop virtualization for multi-core-based application operation. First, we propose a codec configuration of a display protocol with optimal performance in a high load situation due to multi-processing. Second, we propose a virtual CPU scheduling optimization method to reduce scheduling delay in case of CPU contention between virtual machines. As a result of the test, it was confirmed that the H.264 codec of Blast Extreme showed the best and stable frame, and the scheduling performance of the virtual CPU was improved through scheduling optimization.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.10
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• pp.1525-1530
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• 2022

BGP(Border Gateway Protocol) is a routing protocol that is actively used in inter-AS routing on the Internet. However, BGP routing protocol is vulnerable to BGP hijacking attacks that hijack the network by impersonating normal BGP sessions. BGP Hijacking attacks can lead to causing intercept IP traffic or interference with the normal service operation. Recently, BGP hijacking attacks, which have often occurred overseas, have also occurred in Korea. It means threatening the security of the Internet. In this paper, we analyze the overall process of attack through representative attack cases and virtual scenarios of BGP hijacking and based on the results of analyzing the application status of security technology to prevent BGP hijacking attacks by Korea and global major ISPs. It covers the technical proposal of ISPs and autonomous system operators should take to defend against BGP hijacking attacks.

• Journal of Korean Medicine Rehabilitation
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• v.34 no.3
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• pp.65-74
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• 2024

Objectives This study aims to establish a protocol for a systematic review to evaluate the effectiveness and safety of manual therapy (MT) for obstructive sleep apnea (OSA). Methods We will conduct a search for relevant randomized controlled trials using seven databases, including MEDLINE/PubMed, Embase, and the Cochrane Central Register of Controlled Trials. The study includes patients with OSA treated with MT. Comparators include all other treatments excluding MT. The primary outcome is the apnea-hypopnea index; secondary outcomes include mean peripheral oxygen saturation, snoring index, quality of sleep, quality of life, peak nasal inspiratory flow, and adverse events. Results Two independent researchers will select studies based on inclusion criteria and extract necessary data. Risk of bias (RoB) will be assessed using the Cochrane RoB 2.0 tool. Meta-analysis will be conducted if there are two or more studies with the same outcome measure; otherwise, a qualitative analysis will be performed. Subgroup analysis will be conducted based on the type of MT, and evidence certainty will be evaluated using the Grading of Recommendations Assessment, Development, and Evaluation approach. Conclusions This study will evaluate the effect of MT on OSA. By systematically reviewing various MTs, it aims to refine application methods in clinical practice and provide a foundation for future research.

• Journal of Korean Medicine Rehabilitation
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• v.34 no.3
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• pp.107-117
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• 2024

The objective of this study is to report the clinical effects of applying an integrated rehabilitation protocol to four patients with traumatic cervical spinal cord injuries. The treatments applied included acupuncture, cupping and moxibustion, chuna manual therapy, functional electrical stimulation, and other physical therapies. The evaluation methods included American Spinal Injury Association Impairment Scale, functional independence measure (FIM), modified Barthel index (MBI), numeric rating scale (NRS) and other scales. All patients presented marked improvements in FIM, MBI, NRS and other scales, along with increased muscle strength in the manual muscle test. The application of our protocol resulted in clear clinical benefits and enhanced the recovery and quality of life for the patients in this study.