This study focuses on the formation of input release lots in a semiconductor wafer fabrication facility. After the order-lot pegging process assigns lots in the fab to orders and calculates the required quantity of wafers for each product type to meet customers’ orders, the decisions on the formation of input release lots should be made to minimize the production costs of the release lots. Since the number of lots being processed in the wafer fab directly is related to the productivity of the wafer fab, the input lot formation is crucial process to reduce the production costs as well as to improve the efficiency of the wafer fab. Here, the input lot formation occurs before every shift begins in the semiconductor wafer fab. When input quantities (of wafers) for product types are given from results of the order-lot pegging process, lots to be released into the wafer fab should be formed satisfying the lot size requirements. Here, the production cost of a homogeneous lot of the same type of product is less than that of a heterogeneous lot that will be split into the number of lots according to their product types after passing the branch point during the wafer fabrication process. Also, more production cost occurs if a lot becomes more heterogeneous. We developed a multi-dimensional dynamic programming algorithm for the input lot formation problem and showed how to apply the algorithm to solve the problem optimally with an example problem instance. It is necessary to reduce the number of states at each stage in the DP algorithm for practical use. Also, we can apply the proposed DP algorithm together with lot release rules such as CONWIP and UNIFORM.

The purpose of this paper is to study on the characteristic of site planning of Hadrian’s villa. The whole site planning of Hadrian’s villa can be divided by different characteristic four groups(Ⅰ-Ⅳ). It is analysed to the whole site plan of such huge complex and the site planning of partial each group which is organically connected each other. The results of this study are as follows: 1. Hadrian’s villa was arranged in adapt to natural condition according to a gentle inclination by topography and terrain of the whole site which many different buildings are oriented towards natural landscape of the site and the site surroundings. 2. The site planning of Hadrian’s villa is composed of dividing into four groups as plan segmentalized through various land use plan, considering for territory of functional aspect and direction of axis formed by situation and direction of topography and terrain. 3. The concept of site planning to buildings of Hadrian’s villa is composed through each other connection; the first, meeting, crossing and merging with each other from arrangement by several axises, the second, change of direction with as the center a part of corner of buildings and the third, facing or inserting system to side and side, side and a part of corner of building.

UAV (Unmanned Aerial Vehicle), the pilotless plane or drone, draws researchers’ attention at these days for its extended use to various area. The research was initiated for military use of the UAV, but the area of applicable field is extended to surveillance, communication, and even delivery for commercial use. As increasing the interest in UAV, the needs of research for operating the flying object which is not directly visible when it conducts a certain mission to remote place is obviously grown as much as developing high performance pilotless plane is required. One of the project supported by government is related to the use of UAV for logistics fields and controlling UAV to deliver the certain items to isolated or not-easy-to-access place is one of the important issues. At the initial stage of the project, the previous researches for controlling UAV need to be organized to understand current state of art in local researches. Thus, this study is one of the steps to develop the unmanned system for using in military or commercial. Specifically, we focused on reviewing the approaches of controlling UAV from origination to destination in previous in-country researches because the delivery involves the routing planning and the efficient and effective routing plan is critical to success to delivery mission using UAV. This routing plan includes the method to avoid the obstacles and reach the final destination without a crash. This research also present the classification and categorization of the papers and it could guide the researchers, who conduct researches and explore in comparable fields, to catch the current address of the research.

We consider a wafer lot transfer/release planning problem from semiconductor wafer fabrication facilities to probing facilities with the objective of minimizing the deviation of workload and total tardiness of customers’ orders. Due to the complexity of the considered problem, we propose a two-level hierarchical production planning method for the lot transfer problem between two parallel facilities to obtain an executable production plan and schedule. In the higher level, the solution for the reduced mathematical model with Lagrangian relaxation method can be regarded as a coarse good lot transfer/release plan with daily time bucket, and discrete-event simulation is performed to obtain detailed lot processing schedules at the machines with a priority- rule-based scheduling method and the lot transfer/release plan is evaluated in the lower level. To evaluate the performance of the suggested planning method, we provide computational tests on the problems obtained from a set of real data and additional test scenarios in which the several levels of variations are added in the customers’ demands. Results of computational tests showed that the proposed lot transfer/planning architecture generates executable plans within acceptable computational time in the real factories and the total tardiness of orders can be reduced more effectively by using more sophisticated lot transfer methods, such as considering the due date and ready times of lots associated the same order with the mathematical formulation. The proposed method may be implemented for the problem of job assignment in back-end process such as the assignment of chips to be tested from assembly facilities to final test facilities. Also, the proposed method can be improved by considering the sequence dependent setup in the probing facilities.

We focus on the fire scheduling problem (FSP), the problem of determining the sequence of targets to be fired at, for the objective of minimizing makespan to achieve tactical goals. In this paper, we assume that there are m available weapons to fire at n targets (> m) and the weapons are already allocated to targets. One weapon or multiple weapons can fire at one target and these fire operations should start simultaneously while the finish time of them may be different. We develop several dominance properties and a lower bound for the problem, and suggest a branch and bound algorithm implementing them. Also, In addition, heuristic algorithms that can be used for obtaining an initial upper bound in the B&B algorithm and for obtaining good solutions in a short time were developed. Computational experiments are performed on randomly generated test problems and results show that the suggested algorithm solves problems of a medium size in a reasonable amount of computation time. The proposed lower bound, the dominance properties, and the heuristics for upper bound are tested in B&B respectively, and the result showed that lower bound is effective to fathoming nodes and the dominance properties and heuristics also worked well. Also, it is showed that the CPU time required by this algorithm increases rapidly as the problem size increases. Therefore, the suggested B&B algorithm would be limited to solve large size problems. However, the employed heuristic algorithms can be effectively used in the B&B algorithm and can give good solutions for large problems within a few seconds.

Because land based aquaculture is restricted by high investment per rearing volume and control cost, good management planning is important in Land-based aquaculture system case. In this paper master production planning was made to decide the number of rearing, production schedule and efficient allocation of water resources considering biological and economic condition. The purpose of this article is to build the mathematical decision making model that finds the value of decision variable to maximize profit under the constraints. Stocking and harvesting decisions that are made by master production planning are affected by the price system, feed cost, labour cost, power cost and investment cost. To solve the proposed mathematical model, heuristic search algorithm is proposed. The model Input variables are (1) the fish price (2) the fish growth rate (3) critical standing corp (4) labour cost (5) power cost (6) feed coefficient (7) fixed cost. The model outputs are (1) number of rearing fish (2) sales price (3) efficient allocation of water pool.

This study aimed to evaluate the effectiveness of closed season policy using an integer linear programming, targeting the large purse seine fishery in Korea. In the analysis, based on Cheng and Townsend(1993), fishing effort (fishing days by month) was assumed to be distributed for profit maximization of vessels and catch of immature fish was estimated. The analytical results showed that the effects of closed season policy would vary in accordance with the monthly closures in terms of fishing profits and catch of immature fish. A closed season policy by month had different effects on fishing profits and catch of immature fish by species. It implies the importance of considering seasonal changes of fish species when limiting fishing efforts with the closed season policy.

In this paper, we present a multi-period 0-1 knapsack problem which has the cardinality constraints. Theoretically, the presented problem can be regarded as an extension of the multi-period 0-1 knapsack problem. In the multi-period 0-1 knapsack problem, there are n jobs to be performed during m periods. Each job has the execution time and its completion gives profit. All the n jobs are partitioned into m periods, and the jobs belong to i-th period may be performed not later than in the i-th period, i = 1, ⋯, m. The total production time for periods from 1 to i is given by bi for each i = 1, ⋯, m, and the objective is to maximize the total profit. In the extended problem, we can select a specified number of jobs from each of periods associated with the corresponding cardinality constraints. As the extended problem is NP-hard, the branch and bound method is preferable to solve it, and therefore it is important to have efficient procedures for solving its linear programming relaxed problem. So we intensively explore the LP relaxed problem and suggest a polynomial time algorithm. We first decompose the LP relaxed problem into m subproblems associated with each cardinality constraints. Then we identify some new properties based on the parametric analysis. Finally by exploiting the special structure of the LP relaxed problem, we develop an efficient algorithm for the LP relaxed problem. The developed algorithm has a worst case computational complexity of order max[O(n2log n), O(mn2)], where m is the number of periods and n is the total number of jobs. We illustrate a numerical example.

초가속수명시험(HALT:Highly Accelerated Life Test)은 온도변화와 진동을 통해 부품초기 고 장을 빠르게 찾아 개선함으로써 제품의 신뢰성을 향상시킨다. 이에 따라 기업들은 초가속수명시 험에 집중하게 되었고 장비의 수요와 가동률이 증가하고 있다. 그러나 초가속수명시험 장비는 대부분 해외 장비에 의존하고 있어 고장이 발생한 경우 유지보수에 대한 비용이 높고 보전까지 의 시간 또한 길다. 뿐만 아니라 장비에 대한 적절한 보전절차가 없어 비용과 시간의 손실이 발 생되는 실정이다. 본 논문에서는 국산화 개발중인 초가속수명시험 장비에 고장유형과 원인에 따른 계획보전 활 동을 진행 할 수 있도록, FMEA(Failure Modes and Effects Analysis)를 사용하여 계획보전절 차를 제시하였다.

최신의 방사선치료 기법 중의 하나인 체적변조회전치료의 경우 치료 시 방사선은 회전하면서 연속조사를 실시하는 반면 치료계획상에서는 1도 간격의 고정조사형태로 계획되게 된다. 이에 본 연구에서는 체적변조회전치료계획의 정확성을 평가하고자 하 였다. 연속조사에 대한 치료계획이 불가능하므로 3구간에 대해 0.2도 간격, 0.5도 간격, 1.0도 간격, 2.0도 간격으로 치료계획을 실시하여 6개의 용적에 대해 처방선량의 50% 와 70% 용적에 대한 V50과 V70의 평가지표를 비교하였다. 그리고 평가지표 별 용적 에 대한 선속간격 그래프를 통해 연속조사에 대한 값을 외삽하여 추정하였다. 그리고 외삽된 연속조사의 값과 1도간격인 치료계획의 값을 비교하여 오차값을 획득하였다. 그 결과 V50에서는 최대 9.46%의 차이를 보였으며, V70의 경우 최대 25%의 차이를 보였다. 이를 통해 체적변조회전치료계획의 경우 선량의 부정확성을 인지하면서 치료 계획을 실시하여야 하며, 치료계획 컴퓨터의 개발 시 1도 간격이 아닌 본 연구의 결과 에서 처럼 0.5도 간격으로 재설정하여야 할 것이다. 물론, 간격이 좁아지면 계산속도가 느려지므로, 2단계에 걸쳐 계산하는 시스템의 도입도 고려해보아야 할 것이다.해야 할 것이다.