• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.203-206
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• 2008

O-tree 표현법을 이용한 기존의 플로어플랜 알고리즘은 결정적 기법에 기반한 것으로써, 회로의 각 모듈을 차례대로 삭제한 후 가장 좋은 다른 위치에 삽입하는 과정을 함으로써 해 공간을 검색해 간다. 이는 모듈을 처리하는 순서에 따라 결과가 결정되는 단점이 있다. 이런 단점을 해결하기 위해 본 논문에서는 Simulated Annealing 프레임을 이용하여 해 공간을 효과적으로 검색하는 방법을 제시한다. 이웃 해를 탐색하기 위한 플로어 플랜의 변형은 매우 단순하면서도 효과적인 두 가지 방법을 사용한다. 첫째 방법은 한 쌍의 모듈을 선택하여 상호위치를 맞바꾸는 방법이고, 둘째는 임의의 한 모듈을 선택하여 삭제한 후 삽입 가능한 모든 위치 중 임의의 한 곳에 삽입하는 연산을 사용한다. 실험 결과는 매우 고무적이다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.2
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• pp.123-128
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• 2009

In ubiquitous computing environments, service discovery to search for an available service is an important issue. In this paper, we propose an efficient service discovery scheme that is combined a node id-based clustering service discovery scheme and a P2P caching-based information spreading scheme. To search quickly a service, proposed scheme store key information in neighbor's local cache and search services using it's information. We do not use a central look up server and do not rely on flooding. Through simulation, we show that the proposed scheme improves the performance of response time and network load compared to other methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.9C
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• pp.761-770
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• 2010

In this paper, we propose a new Frame Rate Up-Conversion (FRUC) scheme to increase the frame rate from a lower number into a higher one and enhance the decoded video quality at the decoder. The proposed algorithm utilizes the preliminary frames of forward and backward direction using bilateral prediction. In the process of the preliminary frames, an additional interpolation is performed for the occlusion area because if the calculated value of the block with reference frame if larger than the predetermine thresholdn the block is selected as the occlusion area. In order to interpolate the occlusion area, we perform re-search to obtain the osiomal block considerhe osiomnumber of available ne block consblock. The experimental results show that performance of the proposed algorithm has better PSNR and visual quality than the conventional methods.

• Journal of KIISE:Software and Applications
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• v.31 no.9
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• pp.1142-1149
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• 2004

Motion Estimation(ME) has been developed to reduce temporal redundancy in digital video signals and increase data compression ratio. ME is an Important part of video encoding systems, since it can significantly affect the output quality of encoded sequences. However, ME requires high computational complexity, it is difficult to apply to real time video transmission. for this reason, motion estimation algorithms with low computational complexity are viable solutions. In this paper, we present an efficient method with low computational complexity based on spatial and temporal correlations of motion vectors. The proposed method uses temporally and spatially correlated motion information, the motion vector of the block with the same coordinate in the reference frame and the motion vectors of neighboring blocks around the current block in the current frame, to decide the search pattern and the location of search starting point adaptively. Experiments show that the image quality improvement of the proposed method over MVFAST (Motion Vector Field Adaptive Search Technique) and PMVFAST (Predictive Motion Vector Field Adaptive Search Technique) is 0.01～0.3(dB) better and the speedup improvement is about 1.12～l.33 times faster which resulted from lower computational complexity.

• The KIPS Transactions:PartC
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• v.11C no.7 s.96
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• pp.879-888
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• 2004

Ad Node transmits packets to a destination node using routing function of intermediate nodes on the path in Ad Hoc networks. When the link to a next hop node in a path is broken due to the next hop node's mobility, a new route search process is required for continuing packets transmission. The node which recognizes link fault starts a local route recovery or the source node starts a new route search in the on demand routing protocol AODV. In this case, the new route search or the local route search brings packet delays and bad QoSs by packet delay. We propose RPAODV that the node predicts a link fault selects a possible node in neighbor nodes as a new next hop node for the path. The proposed protocol can avoid path faults and improve QoS.

• The KIPS Transactions:PartC
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• v.15C no.3
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• pp.213-220
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• 2008

A MANET is an autonomous, infrastructureless system that consists of mobile nodes. In MANET, on-demand routing protocols are usually used because network topology changes frequently. The current approach in case of broken routes is to flag an error and re-initiate route discovery either at the source or at the intermediate node. Repairing these broken links is a costly affair in terms of routing overhead and delay involved. Therefore, this paper propose a NAODV(Neighbor-aware AODV) protocol that stands on the basis of an AODV. It sets up the route rapidly if it operates for setting the route directly by using sequence number of neighbor nodes without re-search the route when the route to destination node is broken. Also, it reduces loss of packets. We use NS-2 for the computer simulation and validate that the proposed scheme is better than general AODV in terms of packet delivery ratio and average end-to-end delay. Also, when the proposed protocol is applied to the large ad-hoc network with multiple nodes, the performance is more efficient.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.9 s.339
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• pp.11-18
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• 2005

In ad hoc networks, many applications use the broadcast service that is elementary operation to support various important functions such as route discovery procedure. This paper presents several adaptive probabilistic broadcast schemes base on local information to alleviate the broadcast storm problem for wireless ad hoc network. Our schemes dynamically determine the rebroadcast probability at each node based on the neighbor information within two-hop span. Simulation results are presented, which show our schemes have a better performance over the deterministic flooding approach.

• Journal of Intelligence and Information Systems
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• v.13 no.3
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• pp.63-82
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• 2007

In this paper, we propose an adaptive hybrid genetic algorithm (ahGA) approach for effectively solving multistage-based scheduling problems in flexible manufacturing system (FMS) environment. The proposed ahGA uses a neighborhood search technique for local search and an adaptive scheme for regulation of GA parameters in order to improve the solution of FMS scheduling problem and to enhance the performance of genetic search process, respectively. In numerical experiment, we present two types of multistage-based scheduling problems to compare the performances of the proposed ahGA with conventional competing algorithms. Experimental results show that the proposed ahGA outperforms the conventional algorithms.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.9
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• pp.1679-1684
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• 2006

DVB-H(Digital Video Broadcasting for Handhold) is a new standard, currently being developed, which defines mobile enhancements for the DVB-T (DVB-Terrestrial) standard. For the reception of service via mobile handheld devices, seamless mobility and power saving are essential requirements of DVB-H. For seamless handover, the receiver should monitor neighboring cells and it increases the power consumption. And so, power efficient handover scheme to support both mobility and power saving is required. In this paper, we propose power efficient handover scheme to reduce power consumption by reducing the number of frequency scanning during the handover. Through the numerical evaluation, we analyze the performance of handover schemes.

• The KIPS Transactions:PartB
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• v.12B no.4 s.100
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• pp.429-436
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• 2005

A simple stereo matching algorithm using population-based incremental learning(PBIL) is proposed in this paper to decrease the general problem of genetic algorithms, such as memory consumption and inefficiency of search. PBIL is a variation of genetic algorithms using stochastic search and competitive teaming based on a probability vector. The structure of PBIL is simpler than that of other genetic algorithm families, such as serial and parallel ones, due to the use of a probability vector. The PBIL strategy is simplified and adapted for stereo matching circumstances. Thus, gene pool, chromosome crossover, and gene mutation we removed, while the evolution rule, that fitter chromosomes should have higher survival probabilities, is preserved. As a result, memory space is decreased, matching rules are simplified and computation cost is reduced. In addition, a scheme controlling the distance of neighbors for disparity smoothness is inserted to obtain a wide-area consistency of disparities, like a result of coarse-to-fine matchers. Because of this scheme, the proposed algorithm can produce a stable disparity map with a small fixed-size window. Finally, an alterative version of the proposed algorithm without using probability vector is also presented for simpler set-ups.