• Journal of KIISE:Information Networking
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• v.32 no.1
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• pp.89-99
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• 2005

Advances of Internet and rC accelerate distribution and sharing of information, which make P2P(Peer-to-Peer) computing paradigm appear P2P computing Paradigm is the computing paradigm that shares computing resources and services between users directly. A fundamental problem that confronts Peer-to-Peer applications is the efficient location of the node that stoles a desired item. P2P systems treat the majority of their components as equivalent. This purist philosophy is useful from an academic standpoint, since it simplifies algorithmic analysis. In reality, however, some peers are more equal than others. We propose the P2P protocol considering differences of capabilities of computers, which is ignored in previous researches. And we examine the possibility and applications of the protocol. Simulating the Magic Square, we estimate the performances of the protocol with the number of hop and network round time. Finally, we analyze the performance of the protocol with the numerical formula. We call our p2p protocol the Magic Square. Although the numbers that magic square contains have no meaning, the sum of the numbers in magic square is same in each row, column, and main diagonal. The design goals of our p2p protocol are similar query response time and query path length between request peer and response peer, although the network information stored in each peer is not important.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8B
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• pp.1197-1203
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• 2010

A strength of BitTorrent, which is widely used for file sharing today, is due to its peer selection mechanism which is designed to encourage peers to contribute data. In the peer selection phase in BitTorrent, peers to upload the file in a swarm are selected by determining which peers upload the most to themselves. However, the number of peers to upload (i.e., number of unchoked peers) is fixed to four in its peer selection mechanism of BitTorrent, which yields inefficiency because the situation of the swarm may vary frequently (e.g., number of peers in the swarm, download rates, and upload rates). In this paper, we analyze the swarming system performance when the number of unchoked in BitTorrents is not static, but dynamic. For empirical investigation, we established a testbed in Seoul National University by modifying an open-source BitTorrent client, which is popular. Through our experiments, we show that an adaptive mechanism to adjust the number of unchoked peers considering the situation of the swarm is needed to improve the performance of BitTorrent.

• The KIPS Transactions:PartA
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• v.13A no.4 s.101
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• pp.371-380
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• 2006

This paper utilizing model picture of finished clothes in fashion design field various material (textile fabrics) doing Draping directly can invent new design, and do not produce direction sample or poetic theme width and confirm clothes work to simulation. Also, construct database about model and material image and embodied system that can confirm Mapping result by real time. And propose clothes simulation system to dress to 3D human body model of imagination because using several cloth pieces first by process to do so that can do simulation dressing abstracted poetic theme width to 3D model here. Proposed system creates 3D model who put clothes by physical simulation that do fetters to mass-spring model after read 3D human body model file and 2D foundation pattern file. System of this treatise examines collision between triangle that compose human body model for realistic simulation and triangle that compose clothes and achieved reaction processing. Because number of triangle to compose human body is very much, this collision examination and reaction processing need much times. To solve this problem, treatise that see could create realistic picture by method to diminish collision public prosecutor and reaction processing number, and could dress clothes to imagination human body model within water plant taking advantage of Octree space sharing techniques.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.6
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• pp.445-452
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• 2019

In this study, parallel processing codes of k-means clustering algorithm were developed and implemented in a PC-cluster for unsupervised classification of large satellite images. We implemented intra-node code using multicores of CPU (Central Processing Unit) based on OpenMP (Open Multi-Processing), inter-nodes code using a PC-cluster based on message passing interface, and hybrid code using both. The PC-cluster consists of one master node and eight slave nodes, and each node is equipped with eight multicores. Two operating systems, Microsoft Windows and Canonical Ubuntu, were installed in the PC-cluster in turn and tested to compare parallel processing performance. Two multispectral satellite images were tested, which are a medium-capacity LANDSAT 8 OLI (Operational Land Imager) image and a high-capacity Sentinel 2A image. To evaluate the performance of parallel processing, speedup and efficiency were measured. Overall, the speedup was over N / 2 and the efficiency was over 0.5. From the comparison of the two operating systems, the Ubuntu system showed two to three times faster performance. To confirm that the results of the sequential and parallel processing coincide with the other, the center value of each band and the number of classified pixels were compared, and result images were examined by pixel to pixel comparison. It was found that care should be taken to avoid false sharing of OpenMP in intra-node implementation. To process large satellite images in a PC-cluster, code and hardware should be designed to reduce performance degradation caused by file I / O. Also, it was found that performance can differ depending on the operating system installed in a PC-cluster.

• Journal of KIISE:Information Networking
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• v.34 no.6
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• pp.514-524
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• 2007

Recent advances in the speed of multi-rate wireless local area networks (WLANs) and the proliferation of WLAN devices have made rate adaptive, opportunistic scheduling critical for throughput optimization. As WLAN traffic evolves to be more symmetric due to the emerging new applications such as VoWLAN, collaborative download, and peer-to-peer file sharing, opportunistic scheduling at the downlink becomes insufficient for optimized utilization of the single shared wireless channel. However, opportunistic scheduling on the uplink of a WLAN is challenging because wireless channel condition is dynamic and asymmetric. Each transmitting client has to probe the access point to maintain the updated channel conditions at the access point. Moreover, the scheduling decisions must be coordinated at all clients for consistency. This paper presents JUDS, a joint uplink/downlink opportunistic scheduling for WLANs. Through synergistic integration of both the uplink and the downlink scheduling, JUDS maximizes channel diversity at significantly reduced scheduling overhead. It also enforces fair channel sharing between the downlink and uplink traffic. Through extensive QualNet simulations, we show that JUDS improves the overall throughput by up to 127% and achieves close-to-perfect fairness between uplink and downlink traffic.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.32 no.1
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• pp.443-467
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• 2021

The purpose of this study was to conduct interviews with librarians who have experience in establishing local authority data by participating in the national authority sharing system of the National Library of Korea and to understand librarians' recognition and support for the joint utilization of national authority data. For this purpose, a total of 10 librarians who participated in the national authority sharing system project were interviewed by telephone using semi-structured questionnaires. Through this, it was possible to investigate the benefits, difficulties, utilization plans, revision plans of headings, and opinions on necessary support. The results of this study showed that the participants recognized that the joint utilization of national authority data provides the basis for the authority work of the local library and brings about the efficiency of the authority work, but they recognized the difficulty of modifying, selecting, creating new data, lacking knowledge, and lacking support system. The necessary support for the joint utilization of national authority data was provided with education and manuals related to authority, provision of rules related to authority that fully consider the position of the institution, budget and manpower support for system development and maintenance, establishment of communication channel and council, system and data advancement, and incentive to participating libraries. Based on the results of the study, the method and direction for the future operation of the joint utilization of national authority data were presented.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.1
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• pp.5-25
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• 2009

In recent years the popularity of multi-hop wireless networks has been growing. Its flexible topology and abundant routing path enables many types of applications. However, the lack of a centralized controller often makes it difficult to design a reliable service in multi-hop wireless networks. While packet routing has been the center of attention for decades, recent research focuses on data discovery such as file sharing in multi-hop wireless networks. Although there are many peer-to-peer lookup (P2P-lookup) schemes for wired networks, they have inherent limitations for multi-hop wireless networks. First, a wired P2P-lookup builds a search structure on the overlay network and disregards the underlying topology. Second, the performance guarantee often relies on specific topology models such as random graphs, which do not apply to multi-hop wireless networks. Past studies on wireless P2P-lookup either combined existing solutions with known routing algorithms or proposed tree-based routing, which is prone to traffic congestion. In this paper, we present two wireless P2P-lookup schemes that strictly build a topology-dependent structure. We first propose the Ring Interval Graph Search (RIGS) that constructs a DHT only through direct connections between the nodes. We then propose the ValleyWalk, a loosely-structured scheme that requires simple local hints for query routing. Packet-level simulations showed that RIGS can find the target with near-shortest search length and ValleyWalk can find the target with near-shortest search length when there is at least 5% object replication. We also provide an analytic bound on the search length of ValleyWalk.

• The Transactions of the Korea Information Processing Society
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• v.4 no.4
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• pp.908-922
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• 1997

In this paper,we present an dffcient way to describe the commplex meaning embedded in video data for the cintent-based retrival in a video database.Intead of viewing the data stored in a file as continuous bit stream,we associate the desired interval in the stream with a set of atteibute and value pairs which describe its meaning.Since the meaning of video data can be cimplex and can change dyamically. It is necessary to com-bine the fixed schema of attributes used in the traditional database systrm with a description method through a set of attribute and value pairs that can be defined dynamically.As the cintent of viedo data can be expressed differently according to the view point of a user,it is important ot maintain the meaning of the attribute and value pairs cinsistently for different users.This paper proposes the dffctive way to manage the set of attri-bute and value pairs.In addition,it also describes a way to define a new video presentation by separating a video stream phsycally or by sharing the portion of a bit stream,and the new method can minimize the required storage space.

• Journal of Digital Convergence
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• v.12 no.1
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• pp.13-21
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• 2014

The problem of the cases of Soribada and Winny is their duplexity that they could be used legally and illegally. The issue called 'The crime of aiding through the neutral behavior' is about whether the program developer who shared the file sharing program letting unspecified public infringe the copyright could be punished or not. Many theories about limiting the traditional scope of punishment of aider have been maintained. However, it is questionable whether it is possible to limit the scope of punishment following the former cases and theories even for the action that is causal and facilitates the principal's criminal conduct, like the aid through the neutral action which is hard to perceive as illegal aid because of its characteristics. Therefore, using the case of Soribada in Korea and the case of Winny in Japan as the examples of illegal aid through neutral behavior case, this paper examines the characteristics and problems of aid through existing theories and cases, and suggests new scope of punishment limitation standard through the elaboration of the action of aid and judgment of degree.

• Journal of radiological science and technology
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• v.30 no.1
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• pp.47-51
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• 2007

Development of hospital information system and Picture Archiving Communication System is not new in the medical field, and the development of internet and information technology are also universal. In the course of such development, however, it is hard to share medical information without a refined standard format. Especially in the department of radiology, the role of PACS has become very important in interchanging information with other disparate hospital information systems. A specific system needs to be developed that radiological reports are archived into a database efficiently. This includes sharing of medical images. A model is suggested in this study in which an internal system is developed where radiologists store necessary images and transmit them in the standard international clinical format, Clinical Document Architecture, and share the information with hospitals. CDA document generator was made to generate a new file format and separate the existing storage system from the new system. This was to ensure the access to required data in XML documents. The model presented in this study added a process where crucial images in reading are inserted in the CDA radiological report generator. Therefore, this study suggests a storage and transmission model for CDA documents, which is different from the existing DICOM SR. Radiological reports could be better shared, when the application function for inserting images and the analysis of standard clinical terms are completed.