• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.2
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• pp.178-188
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• 2016

The traffic in the wired and wireless networks has increased exponentially because of increase of smart phone and improvement of PC performance. Multimedia services and file transmission such as Facebook, Youtube occupy a large part of the traffic. CDN is a technique that duplicates the contents on a remote web server of content provider to local CDN servers near clients and chooses the optimal CDN server for providing the content to the client in the event of a content request. In this paper, the content request message between CDN servers and the client used the SCRP algorithm utilizing the MST algorithm and the traffic throughput was optimized. The average response time for the content request is reduced by employing HC_LRU cache algorithm that improves the cache hit ratio. The proposed SCRP and HC_LRU algorithm may build a scalable content delivery network system that efficiently utilizes network resources, achieves traffic localization and prevents bottlenecks.

• The KIPS Transactions:PartD
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• v.14D no.7
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• pp.783-790
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• 2007

One of the particulars to be considered for providing wireless web service with PC web page is the hardware environment between PC and mobile device. It is because time cost is required in producing mobile contents to suit environment of the connected terminal. Therefore, server side should take account of response time and disk capacity of server. Response time is delayed by content conversion and disk capacity need to store various versions about one content. This paper suggests a pre-service and post-transcoding method to provide faster response time for a mobile terminal. The pre-service is to minimize response time by placing the top priority in servicing contents saved in cache as much as possible even if the quality of contents serviced to mobile terminal may be low. After pre-service is provided, the mobile content is transcoded for the terminal later. Performance level of method proposed was compared through experiment and the result of analysis was described.

• The KIPS Transactions:PartA
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• v.16A no.5
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• pp.339-346
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• 2009

In order to connect web services, clients generally should use heavy frameworks such as .Net framework and Java run-time environment, which require high performance hardware resources like a personal computer. Therefore, it is impossible for sensor nodes to handle web services due to their limited resources. In this paper, a client agent framework is proposed for dynamically connecting web services in the client node with limited resources. A client agent, which is managed by the framework in other server, has full capability for connecting web services, while a real client has a simple connection module with the client agent. In this framework, a client agent is dynamically generated using the WSDL in the web service server. By using the framework, sensor nodes or mobile devices can enhance their functionalities and services by accessing web services with minimum resources.

• The KIPS Transactions:PartC
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• v.9C no.5
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• pp.709-718
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• 2002

Cluster based VOD systems require elaborate load balancing and buffer management techniques in order to ensure real-time display for multiuser concurrently. In this paper, we propose a new load balancing technique based on the dynamic buffer partitioning in cluster based VOD servers. The proposed technique evenly distribute the user requests into each service node according to its available buffer capacity and disk access rate. In each node, the dynamic buffer partitioning technique dynamically partitions the buffer to minimize the average waiting time for the requests that access the same continuous media. The simulation results show that our proposed technique decreases the average waiting time by evenly distributing the user requests compared with the exiting techniques and then increases the throughput in each node. Particularly under the overloaded condition in the cluster server, the simulation probes that the performance of the proposed technique is better two times than the Generalized Interval Caching based technique.

• The Journal of Information Technology
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• v.3 no.3
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• pp.117-134
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• 2000

Client-server DBMS based on a data-skipping model can exploit client resources effectively by allowing inter-transaction caching. However, inter-transaction caching raises the need of transactional cache consistency maintenance(TCCM) protocol, since each client is able to cache a portion of the database dynamically. Detection-based TCCM schemes can reduce the message overhead required for cache consistency if they validate clients replica asynchronously, and thus they cm show high throughput rates. However, they tend to show high ratios of transaction abort since transactions can access invalid replica. For coping with this drawback, this paper develops a new notion of shadow transaction, which is a backup-purpose one that is kept ready to replace an aborted transaction. This paper proposes a new detection-based TCCM scheme named DL-ST on the basis of the notion of shadow transaction. Using a simulation model, this paper evaluates the effect of shadow transaction in terms of transaction through rate and abort ratio.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.1
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• pp.82-92
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• 2000

This paper introduces an implementation of the diagnosis software for CC-NUMA systems. The CC-NUMA architecture is composed of two or more SMP nodes installed with the specialized hardware to provide cache-coherent operation and the high-speed interconnection network to connect each node, it enables both the high performance and the high scalability. While the CC-NUMA system provides the single system image in the operating system aspect, it should be considered the multiple systems by the diagnostic software. Thus it is difficult to diagnose and manage CC-NUMA system using commercial administration software due to characteristics of the complicated architecture. The remote diagnosis and management are also required with a view to reduce Total Cost of Ownership. In this paper, we design diagnostic software to manage CC-NUMA server system, and propose its mechanism in client-server manner to support remote administration. Additionally, we use the Java-based user interface to enlarge an administrator's accessibility.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.411-413
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• 2010

Now, smart phone markets are grows quickly. So it is needed research of CDN(Contents Delivery Network) technology for contents transmission in mobile networks. Especially the services of smart phone are focused on open platform model. So P2P(Peer to Peer) protocols will be used for mobile network because it is a distributed network architecture composed of participants that make a portion of their resources directly available to other network participants, without the need for a central server. Current research of P2P protocols for mobile network are not activated. The reason is appropriate in the mobile P2P network simulation environment, since it is not provided. So, in this paper we design a mobile P2P simulation system for CDN based on mobile P2P.

• Journal of KIBIM
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• v.11 no.3
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• pp.45-54
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• 2021

The augmented reality (AR) has recently became an attractive technology in construction industry, which can play a critical role in realizing smart construction concepts. The AR has a great potential to help construction workers access digitalized information about design and construction more flexibly and efficiently. Though several AR applications have been introduced for on-site made to enhance on-site and off-site tasks, few are utilized in actual construction fields. This paper proposes a new AR framework that provides on-site managers with an opportunity to easily access the information about construction resources such as workers and equipment. The framework records videos with the camera installed on a wearable AR device and streams the video in a server equipped with high-performance processors, which runs an object detection algorithm on the streamed video in real time. The detection results are sent back to the AR device so that menu buttons are visualized on the detected objects in the user's view. A user is allowed to access the information about a worker or equipment appeared in one's view, by touching the menu button visualized on the resource. This paper details implementing parts of the framework, which requires the data transmission between the AR device and the server. It also discusses thoroughly about accompanied issues and the feasibility of the proposed framework.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.3
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• pp.224-230
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• 2019

In this paper, a new multiple servers conference service system using media control channel/distributed conference manipulation architecture has been presented. This conference service system can handle loads effectively from many conference participants. In this suggested architecture, media control channels are established between conference server, and distributed conference manipulation messages for distributing system loads are exchanged through this channels. These messages are transported between servers using media control channel created after stable transport sessions, and can be used to process server loads according to participants effectively. So this method can be used to implement large scale conference service system. For these purposes, formats of distributed conference manipulation messages which transmitted through media control channels are designed. and messages exchange procedures between conference servers are also presented. The performance of the proposed conference service system has been analysed by experiments, and the results show that the performances are improved according to participants.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.2
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• pp.303-308
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• 2019

Spring framework is widely used as a base technology for e-government frameworks and to the extent it is a standard for web service development tools of Korean public institutions. However, recently, a remote code execution vulnerability(CVE-2018-1270) was found in an application using a spring framework. This paper proposes a method of analyzing the vulnerability experiment using a hacking scenario, Proof Of Concept(POC), in which the spring framework is a hazard to the server. We propose the patch to version 4.3.16 and version 5.0.5 or later as an ultimate response. It is also expected that the proposed experiment analysis on vulnerability of hacking scenario will be used as a data for improving performance of security programs and establishing a new authentication system.