• ETRI Journal
• /
• v.35 no.4
• /
• pp.687-696
• /
• 2013

The development of proxy caching is essential in the area of video-on-demand (VoD) to meet users' expectations. VoD requires high bandwidth and creates high traffic due to the nature of media. Many researchers have developed proxy caching models to reduce bandwidth consumption and traffic. Proxy caching keeps part of a media object to meet the viewing expectations of users without delay and provides interactive playback. If the caching is done continuously, the entire cache space will be exhausted at one stage. Hence, the proxy server must apply cache replacement policies to replace existing objects and allocate the cache space for the incoming objects. Researchers have developed many cache replacement policies by considering several parameters, such as recency, access frequency, cost of retrieval, and size of the object. In this paper, the Weighted-Rank Cache replacement Policy (WRCP) is proposed. This policy uses such parameters as access frequency, aging, and mean access gap ratio and such functions as size and cost of retrieval. The WRCP applies our previously developed proxy caching model, Hot-Point Proxy, at four levels of replacement, depending on the cache requirement. Simulation results show that the WRCP outperforms our earlier model, the Dual Cache Replacement Policy.

• Journal of Information Processing Systems
• /
• v.12 no.2
• /
• pp.249-262
• /
• 2016

In 2004, Yang et al. proposed a threshold proxy signature scheme that efficiently reduced the computational complexity of previous schemes. In 2009, Hu and Zhang presented some security leakages of Yang's scheme and proposed an improvement to eliminate the security leakages that had been pointed out. In this paper, we will point out that both Yang and Hu's schemes still have some security weaknesses, which cannot resist warrant attacks where an adversary can forge valid proxy signatures by changing the warrant $m_w$. We also propose two secure improvements for these schemes.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.1C
• /
• pp.93-101
• /
• 2006

Proxy signature schemes based on delegation of warrant are frequently studied in these days. Proxy signature schemes that used in these days have some problems about the security. Especially, it is difficult to prevent misuse of certification and private key. In this thesis, we propose the more stronger security structure by turning the point from original signer with proxy signer to original signer with verifier, and the proposed protocol is more stronger than previous scheme and can be applied to various PKI based application.

• The KIPS Transactions:PartC
• /
• v.9C no.1
• /
• pp.79-88
• /
• 2002

Transcoding proxy strategy has been widely used as a means to reduce the delay in retrieving Web pages over wireless mobile data service networks. However, this strategy has the serious drawbacks of being a potential point of failure or a bottleneck of the service. We developed a distributed proxy server system in which multiple proxy servers are installed at geographically dispersed locations and share the workloads among them by serving mobile hosts only within assigned regions. A new handoff message protocol to enable handoffs between proxies as the mobile hosts move between regions is proposed. According to the proxy server handoff protocol, a client agent at the mobile horst requests a proxy server to start handoff processing by which two proxy servers synchronize distilled data belonging to a HTTP session that must be maintained across the handoff. Also, we introduce the architecture of the proxy server and the client agent that handles the proxy server handoff. Finally, we evaluate the proposed system through performance test.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.22 no.1
• /
• pp.11-24
• /
• 2012

Without a proper protection mechanism for the signaling messages to be used for the mobility support in the Proxy Mobile IPv6 (PMIPv6), it is also vulnerable to several security attacks such as redirect attack, MITM (Man-In-The-Middle) attack, replay attack and DoS (Denial of Service) attack as in Mobile IPv6. In this paper, we point out some problems of previous authentication mechanisms associated with PMIPv6, and also propose a new fast and secure authentication mechanism applicable to PMIPv6. In addition, it is also shown that the proposed one is more efficient and secure than the previous ones.

• Asia-Pacific Journal of Business
• /
• v.10 no.4
• /
• pp.65-75
• /
• 2019

We point out the limitations of Bloomberg Adjustment beta, shows that long-term beta does not converge with 1 and suggests an alternative to using proxy beta as beta's long-term forecast. We analyze whether the beta produced in the manner proposed by Bloomberg beta or proxy beta meets the purpose of calculating capital costs, for example, for the evaluation of corporate value. In particular, We apply in impairment valuations of assets and some analysis of how it affects. The proposal of the article applied in cases of analysis results are as follows : First, unlike the Bloomberg approach, long-term beta does not converge with market beta and therefore is not suitable as market forecast by beta. Second, estimating the suggested proxy beta as beta's predictive value resulted in Bloomberg beta and other adjustment Beta in the case categories, and the gap was large. Third, applying proxy beta results in a more appropriate valuation of the impairment loss on assets.

• Journal of Korean Academy of Nursing
• /
• v.51 no.1
• /
• pp.15-26
• /
• 2021

Purpose: This study aimed to distinguish and describe the types of perceptions of do not resuscitate (DNR) proxy decisions among families of elderly patients in a long-term care facility. Methods: This exploratory study applied Q-methodology, which focuses on individual subjectivity. Thirty-four Q-statements were selected from 130 Q-populations formed based on the results of in-depth interviews and literature reviews. The P-samples were 34 families of elderly patients in a long-term care hospital in Busan, Korea. They categorized the Q-statements using a 9-point scale. Using the PC-QUANL program, factor analysis was performed with the P-samples along an axis. Results: The families' perceptions of the DNR proxy decision were categorized into three types. Type I, rational acceptance, valued consensus among family members based on comprehensive support from medical staff. Type II, psychological burden, involved hesitance in making a DNR proxy decision because of negative emotions and psychological conflict. Type III, discreet decisions, valued the patients' right to self-determination and desire for a legitimate proxy decision. Type I included 18 participants, which was the most common type, and types II and III each included eight participants. Conclusion: Families' perceptions of DNR proxy decisions vary, requiring tailored care and intervention. We suggest developing and providing interventions that may psychologically support families.

• Proceedings of the KIEE Conference
• /
• 2007.04a
• /
• pp.442-444
• /
• 2007

This paper presents an architecture of UPnP Bridge that allows controlling Non-iP devices from UPnP control point, without modification to Non-IP device or UPnP control point implementations. UPnP devices must provide SSDP discovery, SOAP control and GENA event processes. To represent Non-IP devices to UPnP devices, UPnP Bridge provides these functionalities on behalf of Non-IP devices. We provides two method to interoperability between UPnP and Non-IP devices, Message Field Description, Non-UPnP Proxy devices. And solution to integrate heterogeneous networking standards(RS232C, CAN, IEEE1394, USB) is provided.

• Journal of Communications and Networks
• /
• v.7 no.2
• /
• pp.144-156
• /
• 2005

Video streaming over wireless networks is challenging due to node mobility and high channel error rate. In this paper, we propose a multi-source video streaming (MUVIS) system to support high quality video streaming service over IEEE 802.1l-based wireless networks. We begin by collocating a streaming proxy with the wireless access point to help leverage both the media server and peers in the WLAN. By tracking the peer mobility patterns and performing content discovery among peers, we construct a multi-source sender group and stream video using a rate-distortion optimized scheme. We formulate such a multi-source streaming scenario as a combinatorial packet scheduling problem and introduce the concept of asynchronous clocks to decouple the problem into three steps. First, we decide the membership of the multisource sender group based on the mobility pattern tracking, available video content in each peer and the bandwidth each peer allocates to the multi-source streaming service. Then, we select one sender from the sender group in each optimization instance using asynchronous clocks. Finally, we apply the point-to-point rate-distortion optimization framework between the selected sender-receiver pair. In addition, we implement two different caching strategies, simple caching simple fetching (SCSF) and distortion minimized smart caching (DMSC), in the proxy to investigate the effect of caching on the streaming performance. To design more realistic simulation models, we use the empirical results from corporate wireless networks to generate node mobility. Simulation results show that our proposed multi-source streaming scheme has better performance than the traditional server-only streaming scheme and that proxy-based caching can potentially improve video streaming performance.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.17 no.3
• /
• pp.17-25
• /
• 2007

Delegation of signing capability is a common practice in various applications. Mambo et al. proposed a proxy signatures as a solutions for delegation of signing capability. Proxy signatures allow a designated proxy signer to sign on behalf of an original signer. After the concept of proxy signature scheme is proposed, many variants are proposed to support more general delegation setting. To capture all possible delegation structures, the concept of delegation network was proposed by Aura. ID-based cryptography, which is suited for flexible environment, is desirable to construct a delegation network. Chow et al proposed an ID-based delegation network. In the computational point of view, their solution requires E pairing operations and N elliptic curve scalar multiplications where E and N are the number of edges and nodes in a delegation structure, respectively. In this paper, we proposed an efficient ID-based delegation network which requires only E pairing operations. Moreover, we can design a modified delegation network that requires only N pairing operations.