• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.1
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• pp.1-8
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• 2010

This paper presents global and optimal solution for weapon assignment problems using the Munkres assignment algorithm. We propose a new modeling method of weapon assignment problems concerning some constraints of weapon systems. In this paper, we compares the Munkres weapon assignment algorithm with two other algorithms employing a search tree model in terms of computational complexity and performance. One is an optimal algorithm using exhausted search and the other is a greedy algorithm which selects the first search result as a solution. The experiment results show that the Munkres weapon assignment algorithm has better performance and less computational complexity in comparison with the two other algorithms.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.11a
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• pp.361-364
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• 2006

최근에 제한된 데이터 셋보다 센서 데이터 처리, 웹 서버 로그나 전화 기록과 같은 다양한 트랜잭션 로그 분석 등과 관련된 데이터 스트림 처리에 더 많은 관심이 집중되고 있으며, 특히 데이터 스트림의 질의 처리에 대한 관심이 증가하고 있다. 본 논문에서는 질의 중에서 2 개 이상의 스트림을 조인하는 조인 연속 질의를 처리하는 방법과 성능에 대해서 연구한다. 각 조인의 비용을 스트림의 입력 속도와 조인 선택도를 이용한 조인 비용 모델로 정의하고 그리디 알고리즘을 이용하여 최적화하는 기법을 제안하고 실험을 통해 다양한 스트림 환경에서 최적화 알고리즘이 어떤 성능을 보이는 지를 알아본다.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.421-424
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• 2013

차량 애드 혹 네트워크는 도심 교차로에서 도로의 특성과 차량의 높은 이동성으로 인해 네트워크의 단절이 자주 일어난다. 향상된 지리기반 라우팅 프로토콜인 GBSR(Greedy Border Superiority Routing)은 V2V(Vehicle-to-Vehicle)에 적합하다. 그러나 탐욕모드에서 stale노드가 로컬최대에 직면하는 문제를 가지고 있다. EGBSR(Enhanced GBSR)은 반대 방향의 차량과 같은 방향의 차량에게 보내는 비콘 메시지와 도로 정보를 관리하는 테이블을 이용하여 경로를 탐색하고 설정된 경로를 통해 패킷을 보낸다. 이를 통해 소스노드가 목적지노드에 빠르고 안전하게 패킷을 전달할 수 있는 양방향 라우팅 기법 제안한다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.1
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• pp.76-90
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• 2010

Location Service is required in position-based routing for VANET to provide position information. We propose Grid-based Location service spot(GLSS) scheme for optimized routing path to improve accessibility and load balance in location service. Specific area is defined as Location service spot(LSS) on each grid in this scheme, and all nodes in the grid geocast its location update message and location request message to each LSS. Location request messages are flooded throughout LSSs, location reply messages establish optimized route from the source grid to the destination grid. We evaluated GLSS which establishes optimized route on the grid comparing GPSR in consideration of road condition and geographical features.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.10
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• pp.2252-2258
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• 2013

In this paper, parallel orthogonal matching pursuit (POMP) is proposed to supplement the simultaneous orthogonal matching pursuit (S-OMP) which has been widely used as a greedy algorithm for sparse signal recovery for multiple measurement vector (MMV) problem. The process of POMP is simple but effective: (1) multiple indexes maximally correlated with the observation vector are chosen at the first iteration, (2) the conventional S-OMP process is carried out in parallel for each selected index, (3) the index set which yields the minimum residual is selected for reconstructing the original sparse signal. Empirical simulations show that POMP for MMV outperforms than the conventional S-OMP both in terms of exact recovery ratio (ERR) and mean-squared error (MSE).

• Journal of KIISE:Information Networking
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• v.33 no.6
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• pp.438-450
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• 2006

Geographic routing protocols are very attractive choice for routing in wireless sensor networks because they have been shown to scale better than other alternatives. Under certain ideal conditions, geographic routing works correctly and efficiently. The most commonly used geographic routing protocols include greedy forwarding coupled with face routing. Existing face routing algorithms use planarization techniques that rely on the unit-graph assumption. In real world, many conditions violate the unit-graph assumption of network connectivity, such as location errors, communication voids and radio irregularity, cause failure in planarization and consequently face routing. In this paper, we propose the direction-based geographic routing, which enables energy efficient routing under realistic conditions without planarization techniques. Our proposed approach is for the case in which many sensors need to collect data and send it to a central node. Simulation results show that the protocol exhibits superior performances in terms of energy consumption, delivery success rate, and outperforms the compared protocols.

• Journal of the Korea Society for Simulation
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• v.32 no.1
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• pp.23-34
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• 2023

The purpose of this paper is to review global stochastic optimization algorithms(GSOA) in case binary response experimentation is used and to compare the performances of them. GSOAs utilise estimator of probability of success $\^p$ instead of population probability of success p, since p is unknown and only known by its estimator which has stochastic characteristics. Hill climbing algorithm algorithm, simple random search, random search with random restart, random optimization, simulated annealing and particle swarm algorithm as a population based algorithm are considered as global stochastic optimization algorithms. For the purpose of comparing the algorithms, two types of test functions(one is simple uni-modal the other is complex multi-modal) are proposed and Monte Carlo simulation study is done to measure the performances of the algorithms. All algorithms show similar performances for simple test function. Less greedy algorithms such as Random optimization with Random Restart and Simulated Annealing, Particle Swarm Optimization(PSO) based on population show much better performances for complex multi-modal function.

• Journal of KIISE:Software and Applications
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• v.26 no.9
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• pp.1085-1094
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• 1999

이동 분산 환경에서는 무선 데이타 전송 기법을 통하여 사용자들에게 다양한 정보들을 전달하게 된다. 본 논문은 균등 무선 데이타 방송 환경에서, 빠른 시간에 방송데이타를 접근할 수 있는 방법에 대하여 기술한다. 이를 위하여 무선 방송 데이타의 스케쥴링 문제를 정의하고, 어떤 질의가 접근하는 데이타들의 응집 정도를 나타내는 `질의 거리(Query Distance: QD)'라는 측정 기준을 제시한다. 제안한 질의 거리를 사용하여 각 질의의 우선 순위에 따라 해당 질의가 접근하는 데이타 집합을 방송 스케쥴에 추가하면서 스케쥴을 구성하는 데이타 스케쥴링 기법을 제시한다. 데이타 집합의 스케쥴 구성 과정에서 우선 순위가 높은 질의의 질의 거리를 최소화하면서 낮은 우선 순위 질의들의 질의 거리를 줄이는 스케쥴 확장 규칙들을 사용한다. 예를 이용하여 제안하는 방법에 대하여 설명한 후, 실험을 통해 제안한 방법의 성능을 평가한다.Abstract In mobile distributed systems the data on the air can be accessed by a lot of clients. This paper describes the way clients access the broadcast data in short latency in uniform wireless broadcasting environment. We define the problem of wireless data scheduling and propose a measure, named Query Distance(QD), which represents the coherence degree of data set accessed by a query. By using the measure, we give a data scheduling method that constructs the broadcast schedule by appending each query's data set in greedy way. When constructing the schedule, we use schedule expansion rules that reduce the QD's of lower-frequency queries while minimizing the QD's of the higher-frequency ones. With the use of examples we illustrate the mechanism of the proposed method and we test the performance of our method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.8
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• pp.1784-1789
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• 2013

In this paper, parallel orthogonal matching pursuit (POMP) is proposed to supplement the orthogonal matching pursuit (OMP) which has been widely used as a greedy algorithm for sparse signal recovery. The process of POMP is simple but effective: (1) multiple indexes maximally correlated with the observation vector are chosen at the firest iteration, (2) the conventional OMP process is carried out in parallel for each selected index, (3) the index set which yields the minimum residual is selected for reconstructing the original sparse signal. Empirical simulations show that POMP outperforms than the existing sparse signal recovery algorithms in terms of exact recovery ratio (ERR) for sparse pattern and mean-squared error (MSE) between the estimated signal and the original signal.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.5
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• pp.111-118
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• 2019

Recent graphic processing units (GPUs) provide high throughput by using powerful hardware resources. However, massive memory accesses cause GPU performance degradation due to cache inefficiency. Therefore, the performance of GPU can be improved by reducing thread parallelism when cache suffers memory contention. In this paper, we propose a dynamic warp scheduler which controls thread parallelism according to degree of cache contention. Usually, the greedy then oldest (GTO) policy for issuing warp shows lower parallelism than loose round robin (LRR) policy. Therefore, the proposed warp scheduler employs the LRR warp scheduling policy when Miss Status Holding Register(MSHR) utilization is low. On the other hand, the GTO policy is employed in order to reduce thread parallelism when MSHRs utilization is high. Our proposed technique shows better performance compared with LRR and GTO policy since it selects efficient scheduling policy dynamically. According to our experimental results, our proposed technique provides IPC improvement by 12.8% and 3.5% over LRR and GTO on average, respectively.