• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.5
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• pp.199-203
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• 2009

Recently, Massively Multiplayer Online Role-Playing Games (MMORPGs) has become increasingly popular, which continue to increase the number of game player. The volume of the game world also has been extended on a large scale. Existing Map-based distributed server architecture divides the game world into the rectangular regions and allocates the registered player in each region to the server responsible for that region. Players tend to concentrate in certain regions of the game world, which makes some special server overloaded. This paper proposes to change the boundary between servers to solve such a unbalanced load problem. Our proposed method first finds the overloaded server and then searches for its neighboring lightest loaded server to share with the overload evenly. Finally we implemented performance evaluation to demonstrate the efficiency of this approach.

• Convergence Security Journal
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• v.4 no.3
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• pp.1-8
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• 2004

Large distributed systems such as computational and data grids require that a substantial amount of monitoring data be collected for various tasks such as fault detection, performance analysis, performance tuning, performance prediction, security analysis and scheduling. to cope with this problem, they are needed network monitoring architecture which can collect various network characteristic and analyze network security state. In this paper, we suggest network performance and security analysis system based on network monitoring. The System suggest that users can see distance network state with tuning network parameters.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4794-4800
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• 2012

Many researches have been performed to resist buffer overflow attacks. However, the attack still poses one of the most important issue in system security field. It is because programmers are using library functions containing security hole and once buffer overflow vulnerability has been found, the security patches are distributed after the attacks are widely spreaded. In this paper, we propose a new cache level return address stack architecture for resisting buffer overflow attack. We implemented our hardware onto SimpleScalar simulator and verified its functionality. Our circuit can overcome the various disadvantages of previous works with small overhead.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1539-1543
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• 2004

This paper describes platform overview, system integration and dynamic walking control of the humanoid robot, KHR-2 (KAIST Humanoid Robot - 2). We have developed KHR-2 since 2003. KHR-2 has totally 41 DOF (Degree Of Freedom). Each arm including a hand has 11 DOF and each leg has 6 DOF. Head and trunk also has 6 DOF and 1 DOF respectively. In head, two CCD cameras are used for eye. In order to control all joints, distributed control architecture is adopted to reduce the computation burden of the main controller and to expand the devices easily. The main controller attached its back communicates with sub-controllers in real-time by using CAN (Controller Area Network) protocol. We used Windows XP as its OS (Operating System) for fast development of main control program and easy extension of peripheral devices. And RTX, HAL(Hardware Abstraction Layer) extension program, is used to realize the real-time control in Windows XP environment. We present about real-time control of KHR-2 in Windows XP with RTX and basic walking control algorithm. Details of the KHR-2 are described in this paper.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.9
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• pp.3870-3884
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• 2020

The proposed framework of Four Layer Robust Storage in Cloud (FLRSC) architecture involves host server, local host and edge devices in addition to Virtual Machine Monitoring (VMM). The goal is to protect the privacy of stored data at edge devices. The computational intelligence (CI) part of our algorithm distributes blocks of data to three different layers by partially encoded and forwarded for decoding to the next layer using hash and greed Solomon algorithms. VMM monitoring uses snapshot algorithm to detect intrusion. The proposed system is compared with Tiang Wang method to validate efficiency of data transfer with security. Hence, security is proven against the indexed efficiency. It is an important study to integrate communication between local host software and nearer edge devices through different channels by verifying snapshot using lamport mechanism to ensure integrity and security at software level thereby reducing the latency. It also provides thorough knowledge and understanding about data communication at software level with VMM. The performance evaluation and feasibility study of security in FLRSC against three-layered approach is proven over 2³² blocks of data with 98% accuracy. Practical implications and contributions to the growing knowledge base are highlighted along with directions for further research.

• Bulletin of the Korean Chemical Society
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• v.31 no.7
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• pp.1981-1987
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• 2010

A novel composite (Ag-CNT/$TiO_2$) of silver treated carbon nanotubes (Ag-CNT) and $TiO_2$ was synthesized via wet chemistry followed by a heat treatment. The dispersion and structure of the silver in the synthesized composites determined by X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy(TEM). XRD patterns of the composites showed that the composites contained a mixing anatase and rutile phase. The EDX spectra showed the presence of C, O, Ti and Ag peaks. The $TiO_2$ particles were distributed uniformly in the CNT network, and silver particles were virtually fixed on the surface of the tube. The photocatalysis degraded behaviors of the Ag-CNT/$TiO_2$ composites of the methylene blue, which increased with an increase of the silver component. The Ag-CNT/$TiO_2$ composites have excellent antibacterial activities against Escherichia coli (E. Coli), Pseudomonas aeruginosa (P. Aeru) and Bacillus subtilis (B. Sub) under visible light.

• Journal of Korea Multimedia Society
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• v.20 no.8
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• pp.1369-1378
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• 2017

Pub/Sub (Publish/Subscribe) paradigm is a simple and easy to use model for interconnecting applications in a distributed environment. In general, subscribers register their interests in a topic or a pattern of events and then asynchronously receive events matching their interest, regardless of the events' publisher. In order to build a low latency lightweight pub/sub system for Internet of Things (IoT) services, we propose a GQSFPS (Group Quorum System-based Fog Pub/Sub) system that is a core component in the event-driven service oriented architecture framework for IoT services. The GQSFPS organizes multiple installed pub/sub brokers in the fog servers into a group quorum based P2P (peer-to-peer) topology for the efficient searching and the low latency accessing of events. Therefore, the events of IoT are cached on the basis of group quorum, and the delay-sensitive IoT applications of edge devices can effectively access the cached events from group quorum fog servers in low latency. The performance of the proposed GQSFPS is evaluated through an analytical model, and is compared to the GQPS (grid quorum-based pud/sub system).

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.3
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• pp.1074-1086
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• 2015

We Relay-assisted cellular network architecture has been developed to cover cell-edge users and to improve capacity. However, the deployment of relay stations (RSs) in cellular networks may increase the total energy consumption. Though energy efficiency has become a major concern in cellular networks, little work has studied the energy efficiency of relay-assisted cellular networks by sleep scheduling. In this paper, a distributed base stations (BSs) sleep scheduling scheme in relay-assisted cellular networks is proposed. The goal is to maximize the energy efficiency under the spectral efficiency constraint. Firstly, whether the BSs should be sleeping or active is determined by the traffic profile. Then, the transmission powers of the active BSs are optimized within the game-theoretic framework, by using an interior-point method, so as to maximize the energy efficiency. Simulation results demonstrate that the effectiveness of the proposed scheme is superior to that turning on all the BSs without sleep scheduling.

• Journal of the Korean housing association
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• v.27 no.6
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• pp.19-29
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• 2016

As a lifeway and social change, the neighborhood build up around elementary school based on Perry's Neighbourhood Unit becomes change. Elementary School does not function as a center of residents' activity or community any longer. Activities occurred near the school move to the community streets that many facilities are distributed to, while utilization of facilities near schools becomes lower. On the bases of the current states, this study aims to draw a practical neighborhood center of residential areas by case study. The research is being mainly about low-rise residential areas in Seoul which includes one elementary school at least. In order to deduct the center of neighborhood, the survey takes two steps. At the preliminary survey, conduct the observation and do an interview to investigate awareness and actual status. Also to analyze practical center, do a main survey about land value, pedestrian volume, distribution of public transit and facility density. The research result shows that there is another activated center street not nearby elementary school in every case. This study assumes that the neighborhood center is not limited around elementary school and could variously build up by circumstances. It has significance that we present a question about the traditional theory and also could be references of the future city maintenance in the long term.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.4 s.142
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• pp.411-420
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• 2005

World leading company and research centers have invested much cost and effort into a PLM and digital manufacturing field to obtain their own competitiveness. We have been trying to apply a digital manufacturing, especially simulation to ship production process as a part of PLM implementation for a shipyard. A shipbuilding production system and processes have a complexity and a peculiarity different from other kinds of production systems. So, new analysis and modeling methodology is required to implement digital shipyard. which is a digital manufacturing system for a shipbuilding company. This paper suggests an analysis and simulation modeling methodologies for an implementation of a digital shipyard. New methodologies such as a database-merged simulation, a distributed simulation, a modular simulation with a model library and a 3-tire simulation framework are developed.