• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1269-1276
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• 2011

In the Proxy Mobile IPv6 (PMIPv6), the data transmission performance may be degraded when the two communicating hosts are located within the same mobile domain, since all the data packet shall be delivered by way of Local Mobility Anchor (LMA). In this paper we propose an extensional scheme of PMIPv6 using binding query. In the proposed Query-based PMIPv6 (Q-PMIPv6) scheme, the Mobile Access Gateway (NAG) of Correspondent Node (CN) sends a binding query to LMA to obtain the Proxy Care-of-Address of Mobile Node (MN). Since then, CN and MN can communicate with each other by using an optimized data path. For comparison, we performed the numerical analysis and the ns-2 simulations for the proposed Q-PMIPv6 scheme and the existing PMIPv6 and PMIPv6 Localized Routing (PMIPv6-LR). From the results, we can see that the proposed scheme outperforms the existing PMIPv6 and PMIPv6-LR schemes in terms of the signaling control and data delivery costs.

• Journal of the Korea Society of Computer and Information
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• v.15 no.10
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• pp.113-120
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• 2010

Video proxy server which is located near clients can store the frequently requested video data in storage space in order to minimize initial latency and network traffic significantly. However, due to the limited storage space in video proxy server, an appropriate video selection method is needed to store the videos which are frequently requested by users. Thus, we present a time constraint multiple access technique to efficiently store the video in video proxy server. If the video is requested by user, it is temporarily stored during the predefined interval and then, delivered to the user. A video which is stored is deleted or moved into the storage space of video proxy server depending on the request condition. In addition, we propose a video deletion method in video proxy server for newly stored video data. The simulation results show that the proposed method performs better than other methods in terms of the block hit rate and the number of block deletion.

• Journal of Internet Computing and Services
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• v.13 no.6
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• pp.55-62
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• 2012

Grid web applications by standard Web technology are increasingly used to provide grid service to users as normal Web user interface and service. It is however difficult to integrate a grid security system such as Grid Security Infrastructure (GSI) into Web applications because the delegation way of standard Web security is not the same as the one of Grid security. This can be solved by allowing Web applications to get a Grid credential by using an online credential repository system such as MyProxy. In this paper, we investigate the problem that occurs when MyProxy, which assumes mutual trust between a user and Grid web application, is adapted for achieving security integration between Web and Grid, and we propose a new Grid proxy delegation service to delegate a Grid credential to the Web without assuming mutual trust. In the service, the X.509 proxy delegation process is added to OAuth protocol for credential exchange, and authentication can be done by an external service such as OpenID. So, users can login onto the Grid web application in a single sign-on manner, and are allowed to securely delegate and retrieve multiple credentials for one or more Virtual Organizations.

• Journal of Internet Computing and Services
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• v.5 no.1
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• pp.51-57
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• 2004

Mobile Internet allows users to request critical information and receive swift responses at any places, but mobile users could suffer from unreliable and ill-timed services due to the characteristics of wireless media, One way that reduces possibility of the unsatisfactory services is data replication. Data Replica1ion, however, inevitably induces the overhead of maintaining replica consistency which requires more expensive synchronization mechanism. We propose a new replicated data management scheme in distributed mobile environment, In order to alleviate negative impact of synchronization message overhead in fault-prone mobile Internet environment, we devise a new replication control scheme called proxy quorum consensus (PQC), PQC minimizes the message overhead by coordinating quorum access activities by means of proxy mediated voting (PMV) which exploits reliable proxy hosts instead of unreliable mobile hosts in voting process, We also propose a simulation model to show the performance of PQC. Based on the results of the performance evaluation, we conclude that PQC scheme outperforms the traditional schemes.

• Journal of the Korea Society of Computer and Information
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• v.15 no.6
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• pp.57-64
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• 2010

Due to the limited storage space in video proxy server, it is often required to replace the old video data which is not serviced for long time with the newly requested video. This replacement causes the service delay and increase of network traffic. To circumvent this problem, we propose the an efficient replacement scheme in a video proxy server. In addition, we present a video data management technique for decreasing the number of replacement in video proxy server. For this purpose, we employ a memory in video proxy server. If the video segment which is loaded in memory is requested once again by a different user, this segment is resided in memory. The video in the memory is stored in the video proxy server depending on the consuming pattern by users. The simulation results show that the proposed algorithm performs better than other algorithms in terms of packet hit rate and number of packet replacement.

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

• Physical Therapy Korea
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• v.28 no.2
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• pp.146-153
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• 2021

Background: Researchers have previously commenced examining the degree of concordance between parent proxy and child self-reports on health-related quality of life (HRQOL) of many disease and impairment populations. Objects: To explore the differences between parent proxy and child self-reports on the HRQOL using Korean version of KIDSCREEN-10 questionnaires for applying to elementary school children and their parents who participated for a school-based wellness program. Methods: The focus groups were recruited for a school-based wellness program by implementing the following wellness services: 1) referring to a screening session for detecting potential posture-related musculoskeletal problems and 2) recommending home exercise programs. Before a primary field testing for the program, two focus groups were formed with a group of 9 parents and their 9 elementary school children aged 8-10 years of age. The parent proxy and child self-report versions of KIDSCREEN-10 questionnaires were administered to both groups after completion of the wellness program. Item level Rasch rating scale analysis was applied to compute logit scales of KIDSCREEN-10 questionnaire. Intraclass correlation coefficients (ICCs) and scatterplot of item difficulty between two reports were analyzed. Results: For fit statistics of parent proxy report, all items except 4 items (i.e., psychological well-being, mood/emotions, self-perception, parent relation) were found to be acceptable. For fit statistics of child self-report, all items except 3 items (i.e., psychological well-being, autonomy and home life) were acceptable. The relationship between two reports using ICCs were ranging from weak to very strong at p = 0.05 (i.e, ICCs = 0.011 to 0.905). Scatterplot analysis between two reports showed a major disparity on self-perception item at 95% confidence intervals. Conclusion: Both item level analyses and ICC comparisons provided a disparity between parent proxy and child self-reports of the HRQOL on self-perception item after competing a school-based wellness program. Therapist should consider the item as part of the HRQOL assessment.

• Journal of KIISE:Information Networking
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• v.28 no.4
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• pp.463-476
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• 2001

To support the mobility, mobile computers are generally equipped with lower capability than desktop PCs or workstations in terms of the size of a display, the processing power of CPU and so on. This may give a rise to limitation in mobile computers of supporting multimedia services such as World Wide Web which users would otherwise fully enjoy in desktop PCs. Approaches to reducing the limitations are distillating original multimedia data or converting them to text. Conventional proxy servers for mobile computer simply send distillated image files with the fixed size regardless of the display size of a target mobile computer. Since the cached data is kept separately for each user, they cannot be shared among users with the same display configuration and thus the proxy server could be overloaded. In this paper, we first classify various mobile computers based on their display capability in terms of display sizes and colors. We propose an enhanced proxy server called Class-based proxy that provides a mobile computer with distillated image files in proportion to its class display capacity. The proposed proxy server allows a mobile computer user to have a homepage view similar to that in PC or Workstation. Mobile computers with the same class share the cached image files, which are distillated appropriately for that class. This helps the proxy server to get higher cache hit ratio with improved efficiency and scalability.

• Journal of Oriental Neuropsychiatry
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• v.28 no.2
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• pp.49-59
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• 2017

Objectives: To measure the quality of life in patients according to virtual cerebral palsy severity by using the Korean version of EQ-5D-Y proxy, Visual Analogue Scale (VAS), and Time Trade-Off method (TTO). Methods: The study was conducted in parents of children and adolescents aged 4 to 15 years in Seoul. We analyzed the difference in the utility value according to five levels of cerebral palsy severity in the Gross Motor Function Classification System (GMFCS) and test-retest reliability. Results: 1. There were significant differences in VAS, TTO, and EQ-5D-Y proxy according to the cerebral palsy severity (p<.001). 2. VAS was significantly different according to the respondent's visit to the medical institution, the presence of disease in the respondent, a visit to the child's medical institution, the age of the child, and the sex of the child. The value of TTO was significantly different according to the respondent's visit to the medical institution, respondent's sex, and the age of the child. Also, EQ-5D-Y proxy was significantly different according to the age of the child. 3. Intraclass correlation coefficient values were more than 0.6 for both VAS and TTO at all stages. But for the EQ-5D-Y proxy, the value was less than 0.6 at all stages. Conclusions: The quality of life assessment using EQ-5D-Y proxy showed significant differences in the severity of cerebral palsy. However, large-scale studies using EQ-5D-Y proxy are needed because of low test-retest reliability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.8B
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• pp.521-528
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• 2007

This paper proposes a message authentication scheme to resist potential spam threats in SIP-based VoIP services. Our scheme applies the extended HTTP digest authentication mechanism between the inbound proxy and the UAS to verify that a service request is coming through the valid inbound proxy. The proposed scheme is simple and requires minimal modification the current SIP standards, and effective to filter invalid peer-to-peer spam calls. In this paper, an experimental spam attack using modified open source was tested on a commercial VoIP networks to exploit the possibility of spam attacks in real environment.