• Journal of the Korea Institute of Building Construction
• /
• v.17 no.4
• /
• pp.369-375
• /
• 2017

This study suggests PSO(Particle Swarm Optimization) algorithm that optimizes the snowplow route allocation and the location of the snow control material storage to improve the efficiency in snow removal works. The modified PSO algorithm for improving the search capacity is proposed, and this study suggests the solution representation, the parameter setting, and the fitness function for the given optimization problems. Computational experiments in real-world case are carried out to justify the proposed method and compared with the traditional PSO algorithms. The results show that the proposed algorithms can find the better solution than the traditional PSO algorithms by searching for the wider solution space without falling into the local optima. The finding of this study is efficiently employed to solve the optimization of the snowplow route allocation by minimizing the workload of each snowplow to search the location of the snow control material storage as well.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.11A
• /
• pp.859-866
• /
• 2003

In this paper, we designed the bandwidth allocation scheme with priority consideration for upstream channel access of EthernetPON. The objective of our scheme is to control the multi services in more effective way according to their CoS(Class of Service) or QoS(Quality of Service). The designed scheme considers transmission priority in the both side of OLT and ONU. In the OLT's view, the Two-step scheduling algorithm is applied with which we can support multiple bandwidth allocation policies simultaneously, i.e. SBA for the time-sensitive, constant rate transmission services and DBA for the best-effort services. This Two-step scheduling algorithm reduces the scheduling complexity by separating the process of transmission start time decision from the process of grant generation. In the ONU's view, the proposed scheme controls 8 priority queues of the 802.1d recommended 8 service classes. Higher priority queue is serviced in prior during the allowed GATE time from OLT. The OPNET modeling and simulation result compares the performance of each bandwidth allocation policy with SBA or DBA only approach.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.6
• /
• pp.1502-1510
• /
• 1999

In adaptive job allocation method for multiprocessor systems a job is folded, or split in two halves, to fit for an available subcube in order to reduce the waiting time of jobs. In this method, however, since a job is folded whenever a subcube with the proper size is not found, the prolonged execution time caused by job split may override the savings in waiting time, in which case the total adaptive jobs may be increased. In this paper, an improved adaptive job allocation algorithm, called Estimate-fold allocation, Is presented and evaluated. The proposed algorithm estimates the costs and takes the better of two alternatives ; folding right away and waiting until a bigger subcube becomes available. The average total job execution cost of our algorithm is calculated and compared to those of the conventional adaptive, buddy, and gray-code algorithms through simulations. The results shows that our proposed algorithm performs better than others.

• Journal of Korea Society of Industrial Information Systems
• /
• v.27 no.4
• /
• pp.37-45
• /
• 2022

In this paper, a multi agent-multi task assignment problem, which is a representative problem of combinatorial optimization, is presented. The objective of the problem is to determine the coordinated agent-task assignment that maximizes the sum of the achievement rates of each task. The achievement rate is represented as a concave down increasing function according to the number of agents assigned to the task. The problem is expressed as an NP-hard problem with a non-linear objective function. In this paper, to solve the assignment problem, we propose a hybrid cross-entropy algorithm as an effective and efficient solution methodology. In fact, the general cross-entropy algorithm might have drawbacks (e.g., slow update of parameters and premature convergence) according to problem situations. Compared to the general cross-entropy algorithm, the proposed method is designed to be less likely to have the two drawbacks. We show that the performances of the proposed methods are better than those of the general cross-entropy algorithm through numerical experiments.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.40 no.6
• /
• pp.9-21
• /
• 2003

In this paper, we propose a new submesh allocation scheme which improves the performance of multicomputer systems. The key idea of this allocation scheme is to reduce waiting time of task by minimizing the submesh search time and the submesh a]location delay caused by external fragmentation. This scheme reduces the submesh search time by classifying independent free submeshes according to their types (square, horizontal rectangle, vertical rectangle) and searching a best-fit submesh from the classified free submesh list. If a submesh allocation delay occurs due to external fragmentation, the proposed scheme relocates tasks, executing In allocated submeshes, to another free submeshes and compacts processor fragmentation. This results in reducing the submesh allocation delay. Through simulation, we show that it is more effective to reduce the submesh allocation delay due to external fragmentation than reducing the submesh search time with respect to the waiting time of task. We also show that the proposed strategy improves the performance compared to previous strategies.

• Proceedings of the Korean Information Science Society Conference
• /
• 2004.04a
• /
• pp.40-42
• /
• 2004

본 논문에서는 WDM 네트워크에서 보다 현실적인 파장 변환을 고려하면서 잔여링크를 최대화시킬 수 있는 파장 할당 알고리즘을 제시한다. 기존의 기법들은 각 노드들의 과장 변환 능력을 무시하고 전체 네트워크의 파장 변환 능력을 일률적으로 고정시킨 것을 가정하기 때문에 비효율적이라 할 수 있다. 제안된 기법은 각 노드의 파장 변환 능력을 각각 고려하면서 사용 가능한 잔여링크의 집합을 가능한 최대화 할 수 링(Ring)의 형태로 만든다. 이것은 잔여링크를 최대화하여 어떤 경로 요구가 있더라도 파장을 할당 할 수 있게 한다. 그렇기 때문에 네트워크에서의 블러킹 확률을 최대 19%까지 낮출 수 있었으며, 파장변환 횟수에서 대략 40%의 성능 향상을 보이고, 네트워크의 활용성을 높일 수 있음을 성능 비교를 통해서 볼 수 있다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2012.06a
• /
• pp.245-247
• /
• 2012

최근 멀티코어 프로세서의 활용이 대중화되고 있다. 멀티코어 시스템에서는 소프트웨어가 동시에 여러 코어를 사용하여 동작을 수행 할 때 성능 향상 효과를 얻을 수 있다. 즉, 하나의 소프트웨어가 여러 코어를 동시에 사용할 수 있는 멀티스레드 프로그래밍 기법을 사용할 때 성능을 높일 수 있다. 이러한 환경에서 효율적인 메모리 할당은 데스크톱, 서버 및 과학 등과 같은 응용에 매우 중요하다. 하지만, 동적으로 메모리를 할당하는 것은 메모리 할당 연산과 반환 연산 및 어떤 스레드가 다른 스레드의 힙 영역에 접근하는 것을 처리하기 위한 동기화 문제로 인한 오버헤드가 발생하여 성능에 영향을 끼치는 문제가 발생하게 된다. 따라서 이와 같은 환경에서 실제로 성능에 어느 정도 영향을 끼칠 것인가를 측정할 수 있는 도구가 필요하다. 이에 멀티코어 환경에서 멀티스레드 기법을 사용하여 메모리 할당 연산이 성능에 어떠한 영향을 끼치는지를 측정 및 평가할 수 있는 시뮬레이터인 MAES(Memory Allocation Evaluation Simulator)를 설계하고 구현한다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.4A
• /
• pp.344-350
• /
• 2007

Start after striking space key 2 times. Lately, a lot of researches have been done on the resource allocation for multiuser OFDM(Orthogonal Frequency Division Multiplexing) systems due to its spectral efficiency for high-rate multimedia data services. For multimedia services in which every user is guaranteed to have minimum required bit rate and bit error probability, it is critical to utilize the limited resources efficiently to improve the performance of the system. The introduced allocation method improves spectral efficiency to use the left subcarriers in Zhang's algorithm. By using this method, the system can provide services to more users constantly, except for a bit increasing complexity and memory for deciding the left subcarriers and reallocating the subcarriers.

• The Transactions of the Korea Information Processing Society
• /
• v.5 no.9
• /
• pp.2395-2403
• /
• 1998

Memory allocation problem has two independent goals: minimization of number of memories and minimization of number of registers in one memory Our concern is the ordering of the bindings during memory allocation. We formulate and analyze three different memory allocation algorithms b) changing their binding order. It is shown that when we combine these subtasks and solve them simultaneously by heuristic cost function significant savings (up to 20%) can be obtained in the total area of memories.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2000.04a
• /
• pp.687-690
• /
• 2000

본 논문은 IMT-2000 시스템 MAC 계층에서의 채널할당 운용에 관한 것이다. 기존의 2 세대 무선이동통신인 셀룰라나 PCS 에서는 주로 음성이 주요한 트래픽이었기 때문에 채널 할당에 관한 운용전략이 간단했다. 그러나 무선구간 데이터 트래픽의 급속한 증가는 IMT-2000 시스템의 등장을 가져왔고 이 시스템은 음성과 함께 데이터를 전송하기 때문에 2 세대보다 채널할당이 복잡할 수 밖에 없다. 데이터 트래적 중 web 트래픽이 주요한 부분이 될 것은 자명하다. 그래서 본 논문에서는 대상이 되는 트래픽을 web 트래픽으로 한정하고, web 트래픽을 크게 2 개의 class로 구분했다 : streaming & non-streaming 그리고 다시 각각의 class를 2개, 3개의 subclass(type)로 나눴다. 이 구분과 함에 IMT-2000 시스템의 멀티미디어 트래픽 모델링을 사용하여 시뮬레이션을 행했다. 시뮬레이션은 전용채널, 공용채널의 수, type 별 확률을 변화시키면서 여러 가지 상황을 고려해봤다.