• The Journal of the Korea Contents Association
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• v.8 no.8
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• pp.57-64
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• 2008

In this paper, to resolve the problem caused by a network state information inaccuracy the slow delay time that conclusion of network state of one way delay time which accuracy delay time information, according to network state changes on the based TFRC flow control, and suggest that flow control mechanism to adjust transfer rate fit of real time multimedia data. In simulation, to measure of netowork state information that on the average about 12% difference of compared RTT and $OWD{\times}2$. When used RTT, used fair bandwidth TFRC much better than TCP about 32%, when used OWD, difference about 3% used fair bandwidth. Thus, conclusion of accuracy network state that used fair bandwidth according to network state changes on the based TFRC, users can support service of high quality that flow control mechanism to adjust transfer rate fit of real time data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.107-110
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• 2015

In this paper, we propose a coalitonal game theoritic approach to the power control problem in resource-constrained wireless sensor networks, where the objective is to enhance power efficiency of individual sensors while providing the QoS requirements. We model this problem as two-sided one-to-one matching game and deploly deferred acceptance procedure that produces a single matching in the core. Furthermore, we show that, by applying the procedure repeatedly, a certain stable state is achieved where no sensor can anticipate improvements in their power efficiency as far as all of them are subject to their own QoS constraints. We evaluate our proposal by comparing them with cluster-based and the local optimal solution obtained by maximizing the total system energy efficiency, where the objective function is non-convex.

• The KIPS Transactions:PartC
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• v.11C no.3
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• pp.353-360
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• 2004

In this Paper, We propose an efficient iteration decoding control method with variable iteration decoding of iteration codes decoding using Cyclic Redundancy Check. As the number of iterations increases, the bit error rate and frame error rate of the decoder decrease and the incremental improvement gradually diminishes. However, when the iteration decoding number is increased, it require much delay and amount of processing time for decoding. Also, It can be observed the error nor that the performance cannot be improved even though increasing of the number of iterations and SNR. So, Suitable number of iterations for stopping criterion is required. we propose variable iteration control method to adapt variation of channel using Frame Error-Check indicator. Therefore, the amount of computation and the number of iterations required for iteration decoding with CRC method can be reduced without sacrificing performance.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.10
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• pp.2616-2628
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• 1994

Recently the Time Delay Control(TDC) method has been proposed as a promising technique in the robust control area, where the plant has unknown dynamics with parameter variations and substantial disturbances are present. When TDC is applied to the plant with saturation nonlinearity, however, the so called windup phenomena are observed to arise, causing excessive overshoot and instability. In order to solve this problem, we have proposed an anti-windup method for TDC. The stability of the overall system has been analyzed for a class of LTI MIMO system. The effectiveness for the proposed method has been shown with simulation and experiment results.

• Proceedings of the Korea Information Processing Society Conference
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• 2024.05a
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• pp.137-140
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• 2024

가상 및 증강현실(VR/AR), 원격 제어, 산업 자동화를 위한 실시간 애플리케이션이 증가함에 따라 무선 통신 네트워크의 처리량과 지연시간 성능이 중요해졌다. 이에 따라 Wi-Fi 8 에서는 초고신뢰 (Ultra-High Reliable, UHR)을 목표로 표준화가 진행 중이며 다수의 AP가 협력하여 데이터를 전송하는 다중 AP 협력 기법이 핵심 기술로 논의되고 있다. 하지만 기존의 다중 AP 협력 환경에서 협력 전송을 위한 제어 정보로 인한 간섭 증가와 OBSS(Overlapped Basic Service Set) 간섭 문제를 고려하지 못하고 있다. 따라서 본 논문에서는 효율적인 다중 AP 협력 전송을 위한 단순화된 채널 관리 방법(Simplified Channel Management Mechanism, SCMM)을 제안한다. 실험 결과에 따르면, SCMM 이 종래모델 대비 처리량은 평균 21.23% 증가했고, 지연시간은 평균 51.02% 감소했다.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11b
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• pp.705-708
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• 2003

본 논문에서는 무선 센서 네트워크의 특성을 고려한 미디어제어 프로토콜의 설계에 있어서의 고려사항 및 설계기법에 대해서 제안하고 있다. 무선 센서 네트워크는 제한된 에너지를 가지는 배터리를 에너지원으로 사용하는 센싱 디바이스들로 구성되어 있으며, 이러한 디바이스들로 구성된 네트워크는 하나 혹은 그 이상의 공통의 작업을 수행하는데 그 목적이 있다. 일반적으로 무선 센서네트워크는 ad hoc 헝태의 구조를 가지며, 각각의 노드들은 장시간동안 비활성화 상태에 머무르게 되며, 센싱을 하기 위한 특정 이벤트가 발생하였을 때만 활성 상태로 전이하게 된다. 이와 같은 센서 네트워크의 특성은 IEEE802.11 과 같은 기존의 무선 미디어 제어 프로토콜과는 차별성을 띄게 된다. 센서 네트워크는 노드별 미디어 접근 공정성이나 시간지연보다는 에너지절약과 위상자동설정에 더 중점을 두고 있기 때문에 이에 적합한 미디어 제어 기술이 필요한 것이다. 본 고에서는 에너지 소모를 최소화하고 위상 자동 설정을 지원하기 위한 3 가지의 기법들에 대해서 제안하고자 한다. 첫째로 이벤트 발생 여부에 따른 노드의 신호감지 및 Sleep 상태 전이 및 이웃 노드들과의 가상동기화기법을 이용한 에너지 절약 기법에 대해서 제안하고, 충돌회피 기법에 대해서 살펴보도록 하겠다.

• Journal of KIISE
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• v.43 no.5
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• pp.606-612
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• 2016

The multi-view video service based on the DASH(Dynamic Adaptive Streaming over HTTP) switches the viewpoint or object which is selected by the user among the multiple video streams captured by multiple cameras. However, the problem is that the conventional DASH-based multi-view video service takes a long time to switch the viewpoint. The reason is that the conventional scheme switches to the new video stream after consuming all buffered segments of the previous video stream. In this paper, we propose a video streaming scheme for minimizing the viewpoint switching delay in the DASH-based multi-view video service. In order to minimize the viewpoint switching delay, the proposed scheme configures the video streams by controlling the GoP (Group of Pictures) size and controls the client buffer based on bandwidth estimation and playback buffer occupancy. Through the experimental results, we prove that the proposed scheme reduces the viewpoint switching delay.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.10
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• pp.2554-2566
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• 1994

Robot position/force control has been a difficult task owing to the interaction between a robot and an environment with a rather high stiffness. In addition to the dynamic instability, the interaction causes the following problem : 1) chattering at steady-state, 2) dynamic coupling effect of robot, and 3) performance degradation due to a titled environment. To solve the problem, the Time Delay Control(TDC), which has been known to be quiet robust to plant uncertainties and disturbances, has been applied. In conjunction to TDC, the following three ideas were also used : 1) To reduce the amplitude of the chattering at the steady state, a novel scheme was adopted to enhance the resolution type solution of A/D conversion for the force sensor. 2) To reduce the dynamic coupling, a trajectory type position command was tried on a comparative basis to the step command, as well as a more accurate mass matrix was used instead of the constant mass matrix. 3) And finally to improve the performance in the tilted environment, force derivatives instead of position derivatives were used in the TDC law. Computer simulations and experiments resulted in obvious improvements on the quality of the hybrid control, thereby clearly demonstrating the effectiveness of TDC with the proposed ideas.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.176-179
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• 2011

본 논문은 IEEE 802.11기반 무선 멀티홉 환경에서 은닉 노드가 존재할 때 전체 시스템의 효율 저하를 최소화 하면서도 평균 시간 지연 요구를 만족할 수 있는 경쟁 윈도우 제어 알고리즘을 제안한다. 이에 적용되는 최소 경쟁 윈도우 기준값을 주어진 topology에 따라 도출하고 각 트래픽 플로어의 QoS 요구조건 만족과 은닉노드가 존재할 경우에 성능개선을 위한 경쟁 윈도우 제어 패턴을 조절한다. 제안하는 경쟁 윈도우 제어 기법을 ns-2 시뮬레이션을 통해 검증하고, 모든 QoS 요구를 수용하면서 전체 성능 개선을 보이는 결과를 구하였다.

• Journal of Advanced Navigation Technology
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• v.15 no.3
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• pp.364-371
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• 2011

In P2P distribution mobile networks, QoS of streaming media services are under heavy influence from overheads such as congestion, latency, and interference. The problem is further complicated by the fact that the popularity of media objects changes over time. This paper proposes a new FSMS+ (Fuzzy Similarity-based Multi-level Streaming Scheme) which minimizes performance degradation of streaming services due to overhead. We then utilize fuzzy similarity-based relevance that can dynamically stream the streaming media object with minimum overhead. The simulation result showed that the proposed scheme has better performance in retransmission rate, congestion control rate and latency rate than the other existing methods of distance method, DC (disk caching) method, and prefix method.