• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.9
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• pp.838-844
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• 2004

In a long road tunnel, a tunnel ventilation system may be used in order to reduce the pollution below the required level. To develop control algorithms for a tunnel ventilation system, a dynamic simulation program may be used to predict the pollution level in a tunnel. Research was carried out to develop better pollution models for a tunnel ventilation control system. A neural network structure was adopted and compared by using actual poilution data. Simulation results showed that the dynamic model developed by a neural network may be effective for the development of tunnel ventilation control algorithms.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.121-124
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• 2001

Dynamic Source Route(DSR) protocol is a simple and efficient routing protocol designed specially for use of the multi-hop Ad Hoc Network. DSR allows the network to be completely self-organized and self-configured without the need for any existing infrastructure or administration. DSR protocol consists of the two mechanisms of Router discovery and Router Maintenance, works entirely On-demand in all aspects. In this paper, we will present the performance of DSR protocol on the multi-hop wireless Ad Hoc Networks, illustrate it with simulation, and then analysis the algorism of DSR.

• Convergence Security Journal
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• v.11 no.1
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• pp.3-10
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• 2011

This paper proposes DPA(Dynamic Priority Assignment) MAC protocol to improve the traffic QoS on the HFC-CATV(Hybrid Fiber Coax CAble TeleVision) network. In results, DPA MAC protocol is the best performance compare with to IEEE 802.14a MAC in mean request delay, mean access delay. Also, the paper prove a reliability of proposed protocol through comparison between performance analysis and simulation result of DAP MAC protocol.

• Journal of Information Processing Systems
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• v.6 no.4
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• pp.501-510
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• 2010

Wireless sensor networks consist of sensor nodes which are expected to be battery-powered and are hard to replace or recharge. Thus, reducing the energy consumption of sensor nodes is an important design consideration in wireless sensor networks. For the implementation of an energy-efficient MAC protocol, a Sensor-MAC based on the IEEE 802.11 protocol, which has energy efficient scheduling, has been proposed. In this paper, we propose a Dynamic S-MAC that adapts dynamically to the network-traffic state. The dynamic S-MAC protocol improves the energy consumption of the S-MAC by changing the frame length according to the network-traffic state. Using an NS-2 Simulator, we compare the performance of the Dynamic S-MAC with that of the S-MAC protocol.

• Proceedings of the KOR-KST Conference
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• 2002.02a
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• pp.97-139
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• 2002

The aim of the present study is to find a good quality user equilibrium assignments under time varying condition. For this purpose, this study introduces a dynamic network loading method that can maintain correct flow propagation as well as flow conservation, and it develops a novel solution algorithm that does not need evaluation of the objective function by modifying the Schittenhelm (1990)'s algorithm. This novel algorithm turns out to be efficient and convenient compared to the conventional Frank-Wolfe (1956) algorithm because the former finds solutions based on routes rather than links so that it can maintain correct flow propagation intrinsically in the time-varying network conditions. The application of dynamic user equilibrium (DUE) assignment model with this novel solution algorithm to test networks including medium-sized one shows that the present DUE assignment model gives rise to high quality discrete time solutions when we adopt the deterministic queuing model for a link performance function, and we associate flows and costs in a proper way.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.693-694
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• 2014

This paper proposes a new pipelined dynamic bandwidth allocation algorithm for XG-PON (10-Gbps-capable passive optical network) passive optical networks) system. The pipelined algorithm is used when a dynamic bandwidth allocation algorithm cannot finished in an unit time. In the proposed mechanism, the request is immediately transferred to each pipeline block to improve performance.

• International Journal of Computer Science & Network Security
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• v.24 no.4
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• pp.192-196
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• 2024

The memory coherence problem occurs while mapping shared virtual memory in a loosely coupled multiprocessors setup. Memory is considered coherent if a read operation provides same data written in the last write operation. The problem is addressed in the literature using different algorithms. The big question is on the correctness of such a distributed algorithm. Formal verification is the principal term for a group of techniques that routinely use an analysis that is established on mathematical transformations to conclude the rightness of hardware or software behavior in divergence to dynamic verification techniques. This paper uses UPPAAL model checker to model the dynamic distributed algorithm for shared virtual memory given by K.Li and P.Hudak. We analyse the mechanism to keep the coherence of memory in every read and write operation by using a dynamic distributed algorithm. Our results show that the dynamic distributed algorithm for shared virtual memory partially fulfils its functional requirements.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2001.01a
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• pp.50-58
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• 2001

Modern day networks are increasingly moving towards peer to peer architecture where routing tasks will not be limited to some dedicated routers, but instead all computers in a network will take part in some routing task. Since there are no specialized routers, each node performs some routing tasks and information passes from one neighbouring node to another, not in the form of dumb data, but as intelligent virtual agents or active code that performs some tasks by executing at intermediate nodes in its itinerary. The mobile agents can run, and they are free to d other tasks as the agent will take care of the routing tasks. The mobile agents because of their inherent 'intelligence'are better able to execute complex routing tasks and handle unexpected situations as compared to traditional routing techniques. In a modern day dynamic network users get connected frequently, change neighbours and disconnect at a rapid pace. There can be unexpected link failure as well. The mobile agent based routing system should be able to react to these situations in a fact and efficient manner so that information regarding change in topology propagates quickly and at the same time the network should not get burdened with traffic. We intend to build such a system.

• Journal of Korea Multimedia Society
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• v.21 no.10
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• pp.1182-1194
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• 2018

The Dynamic Adaptive Streaming over HTTP(DASH) is envisioned to evolve to meet an increasing demand on providing seamless video streaming services in the near future. The DASH performance heavily depends on the client's adaptive quality selection algorithm that is not included in the standard. The existing conventional algorithms are basically based on a procedural algorithm that is not easy to capture and reflect all variations of dynamic network and traffic conditions in a variety of network environments. To solve this problem, this paper proposes a novel quality selection mechanism based on the Deep Q-Network(DQN) model, the DQN-based DASH Adaptive Bitrate(ABR) mechanism. The proposed mechanism adopts a new reward calculation method based on five major performance metrics to reflect the current conditions of networks and devices in real time. In addition, the size of the consecutive video segment to be downloaded is also considered as a major learning metric to reflect a variety of video encodings. Experimental results show that the proposed mechanism quickly selects a suitable video quality even in high error rate environments, significantly reducing frequency of quality changes compared to the existing algorithm and simultaneously improving average video quality during video playback.

• The KIPS Transactions:PartA
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• v.16A no.6
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• pp.489-500
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• 2009

Robots have limited computing resources and robot services have different requirement such as sensors, actuators, computational capabilities and timeliness. In this paper, we propose a dynamic management method of service execution contexts to perform various services efficiently and to meet the time constraint of service in network-based robots. The proposed method is tested in the real network-based robot system. The results show that the real-time requirement for services is satisfied and the resource utilization is improved. The proposed method provides the extendability and flexibility of sensors and services by aptly modifying service execution contexts and increases the reusability of service.