• Journal of Electrical Engineering and Technology
• /
• 제13권4호
• /
• pp.1566-1577
• /
• 2018

This paper presents a stability analysis of AC-DC power system feeding a speed controlled DC motor in which this load behaves as a constant power load (CPL). A CPL can significantly degrade power system stability margin. Hence, the stability analysis is very important. The DQ and generalized state-space averaging methods are used to derive the mathematical model suitable for stability issues. The paper analyzes the stability of power systems for both speed control natural frequency and DC-link parameter variations and takes into account controlled speed motor dynamics. However, accurate DC-link filter and DC motor parameters are very important for the stability study of practical systems. According to the measurement errors and a large variation in a DC-link capacitor value, the system identification is needed to provide the accurate parameters. Therefore, the paper also presents the identification of system parameters using the adaptive Tabu search technique. The stability margins can be then predicted via the eigenvalue theorem with the resulting dynamic model. The intensive time-domain simulations and experimental results are used to support the theoretical results.

• 한국소음진동공학회논문집
• /
• 제15권11호
• /
• pp.1223-1231
• /
• 2005

Recently, the issue of ship nitration due to the large scale, high speed and lightweight of ship is emerging. For pleasantness in the cabin, shipbuilders are asked for strict vibration criteria and the degree of nitration level at a deckhouse became an important condition for taking order from customers. This study proposes a new optimization framework that is NASTRAN external call type optimization method (OptShip) and applies to an optimum design to decrease the nitration level of a deckhouse. The merits of this method are capable of using of global searching method and selecting of various objective function and design variables. The global optimization algorithms used here are random tabu search method which has fast converging speed and searches various size domains and genetic algorithm which searches multi-point solutions and has a good search capability in a complex space. By adapting OptShip to full-scale model, the validity of the suggested method was investigated.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2015년도 추계 학술논문 발표대회
• /
• pp.196-197
• /
• 2015

In tall building construction, time for transporting form affects formwork duration as plan size has become larger and quantity of inputted form has been increased. Thus, necessity of systematic dismantlement sequence of form has been increased to reduce the duration of formwork. Tabu search has been efficiently applied to solve problem of combinatorial optimization by using tabu list which can improve combination values. Therefore, this study proposes optimization model of dismantlement sequence of table form which has been preferred in tall building construction, to reduce the formwork duration by minimizing time for transporting form.

• Journal of Communications and Networks
• /
• 제7권4호
• /
• pp.471-477
• /
• 2005

This paper proposes an efficient constraint-based optimization model for the design of 3G mobile networks, such as universal mobile telecommunications system (UMTS). The model concerns about finding a set of sites for locating radio network controllers (RNCs) from a set of pre-defined candidate sites, and at the same time optimally assigning node Bs to the selected RNCs. All these choices must satisfy a set of constraints and optimize an objective function. This problem is NP-hard and consequently cannot be practically solved by exact methods for real size networks. Thus, this paper proposes a hybrid search strategy for tackling this complex and combinatorial optimization problem. The proposed hybrid search strategy is composed of three phases: A constraint satisfaction method with an embedded problem-specific goal which guides the search for a good initial solution, an optimization phase using local search algorithms, such as tabu algorithm, and a post­optimization phase to improve solutions from the second phase by using a constraint optimization procedure. Computational results show that the proposed search strategy and the model are highly efficient. Optimal solutions are always obtained for small or medium sized problems. For large sized problems, the final results are on average within $5.77\%$ to $7.48\%$ of the lower bounds.

• Management Science and Financial Engineering
• /
• 제18권1호
• /
• pp.27-37
• /
• 2012

This paper is motivated by a military cargo-plane routing problem which is a pickup-and-delivery problem in which load splits and node revisits are allowed (PDPLS). Although this recent evolution of a VRP-model enhances the efficiency of routing, a solution method is more of a challenge since the node revisits entail closed walks in modeling vehicle routes. For such a case, even a compact IP-formulation is not available and an effective method had been lacking until Nowak et al. (2008b) proposed a heuristic based on a tabu search. Their method provides very reasonable solu-tions as demonstrated by the experiments not only in their paper (Nowak et al., 2008b) but also in ours. However, the computation time seems intensive especially for the class of problems with dynamic transportation requests, including the military cargo-plane routing problem. This paper proposes a more scalable algorithm hybridizing a tabu search for pricing subproblem paused as a single-vehicle routing problem, with a column generation approach based on Dantzig-Wolfe decomposition. As tested on a wide variety of instances, our algorithm produces, in average, a solution of an equiva-lent quality in 10~20% of the computation time of the previous method.

• 산업경영시스템학회지
• /
• 제19권40호
• /
• pp.169-178
• /
• 1996

Geographically dispersed computing system is made of computers interconnected by a telecommunications network. To make the system operated efficiently, system designer must determine the allocation of data files to each node. In designing such distributed computing system, the most important issue is the determination of the numbers and the locations where database files are allocated. This is commonly referred to as the file allocation problem (FAP)[3]. The proposed model is a 0/l integer programming problem minimizing the sum of file storage costs and communication(query and update) costs. File allocation problem belongs to the class of NP-Complete problems. Because of the complexity, it is hard to solve. So, this paper presents an efficient heuristic algorithm to solve the file allocation problem using Tabu Search Technique. By comparing the optimal solutions with the heuristic solutions, it is believed that the proposed heuristic algorithm gives good solutions. Through the experimentation of various starting points and tabu restrictions, this paper presents fast and efficient method to solve the file allocation problem in the distributed computing system.

• 경영과학
• /
• 제30권2호
• /
• pp.31-42
• /
• 2013

The vehicle routing problem (VRP) can be described as a problem to find the optimum traveling routes from one or several depot (s) to number of geographically scattered customers. This study executes a revised Heterogeneous Vehicle Routing Problem (HVRP) to minimize the cost that needs to conduct efficiently the snow removal operations of Air Wing under available resources and limited operations time. For this HVRP, we model the algorithm of an hybrid Ant Colony System (ACS). In the initial step for finding a solution, the modeled algorithm applies various alterations of a parameter that presents an amount of pheromone coming out from ants. This improvement of the initial solution illustrates to affect to derive better result ultimately. The purpose of this study proves that the algorithm using Hybrid heuristic incorporated in tabu and ACS develops the early studies to search best solution.

• 한국항해항만학회지
• /
• 제38권3호
• /
• pp.299-305
• /
• 2014

트랜스포터란 조선소에서 작업장 간에 조선 블록을 운반하는 장비이다. 트랜스포터 일정 계획을 효율적으로 하는 것은 선박 건조과정에서 매우 중요한 역할을 한다. 블록 운반에 있어서의 트랜스포터 일정 계획에 관한 몇몇 연구들이 수행되었다. 이러한 연구들은 트랜스포터 결합을 고려하지 않았다. 본 논문에서는 결합을 고려한 효율적인 트랜스포터 일정 계획 모형을 제안한다. 수리적 모형에서는 운영 비용을 최소화하면서 트랜스포터 간의 작업 부하를 가능한 균등하게 하는 것을 목적으로 하였다. 또한 본 모형의 해를 탐색하기 위해 타부 서치 기반의 세 가지 휴리스틱 알고리즘을 제시하였으며 컴퓨터 실험을 통해 제안된 휴리스틱들의 효율성을 검증하였다.

• 한국ITS학회 논문지
• /
• 제23권2호
• /
• pp.142-156
• /
• 2024

교통부문 탄소중립을 위한 전기자동차로의 전환에 있어 충분한 충전 인프라의 구축은 중요한 선행요소이다. 특히, 거주지의 충전 인프라 구축은 필수적이다. 우리나라의 주거형태는 주로 공동주택이며, 다수의 거주민을 위한 공공 충전기가 공급되어야 한다. 정부는 충전시설과 전기자동차 전용주차구역의 확보를 법적으로 규정하고 있으나, 주차면수만을 산출근거로 한다. 완속 충전기는 3.5kW 과금형 콘센트와 7kW 완속 충전기가 주를 이룬다. 전자가 충전기 설치 및 이용에 유리하지만, 충전속도가 느려 두 가지 형태의 충전기는 양립이 필요하다. 본 연구에서는 일일 주행거리를 기반으로 산정한 전기자동차의 충전 수요에 대응할 수 있는 충전기를 할당하는 최적화 모형을 제시하였다. 또한, 메타 휴리스틱 알고리즘인 Tabu Search를 사용하여 최적화 모형을 만족하는 것과 동시에 충전기 공급 및 충전 비용을 최소화할 수 있는 완속 충전기 공급량을 산정하였다. 사례 분석을 위해 개인통행실태조사자료를 사용해 주행거리를 산정하였으며, 가상의 충전 시나리오 및 환경을 설정하여 100대의 전기자동차 충전 수요에 대응하는 22대의 3.5kW 과금형 콘센트를 최적 공급량으로 산정하였다.

• 한국경영과학회지
• /
• 제23권1호
• /
• pp.17-28
• /
• 1998

This study suggests a procedure for designing cellular manufacturing systems (CMS) which are combined with automated guided vehicles (AGVs) using a tandem configuration. So far most of the previous studies have dealt with conventional design problems not considering the layout and the characteristics of transporters used in CMS. A mathematical model is developed using the service time to perform material transfers as a suitable meassure. The service capacity of AGVs and space limitations are also reflected in this model. As the model can be shown strongly NP-hard, a heuristic algorithm is presented, in which each cell is temporarily formed using both the set covering model and similarity coefficients, and then locations of the cells are determined by means of tabu search and finally machine perturbations are carried out. An example problem is solved to demonstrate the algorithm developed.