Thai Journal of Operations Reseach : TJOR 2018-12-24T17:31:04+07:00 รศ.ดร.กาญจ์นภา อมรัชกุล Open Journal Systems <p>วารสารไทยการวิจัยดำเนินงาน (Thai Journal of Operations Research : TJOR) เกิดขึ้นจากความร่วมมือของคณาจารย์ และนักวิจัยในเครือข่ายการวิจัยดำเนินงาน (Operations Research Network of Thailand, OR-NET) โดยมีวัตถุประสงค์เพื่อส่งเสริมและเผยแพร่ผลงานทางวิชาการด้านการวิจัยดำเนินงานที่มีคุณภาพ&nbsp;วารสารไทยการวิจัยดำเนินงานเป็นวารสารอิเล็กทรอนิกส์ (E-Journal) ที่มีกำหนดออกปีละ 2 ฉบับ คือประมาณเดือนมิถุนายน และเดือนธันวาคมของทุกปี&nbsp;</p> <ul> <li class="show">วารสารไทยการวิจัยดำเนินงาน (Thai Journal of Operations Research)&nbsp;<strong>ได้รับการจัดกลุ่มวารสารที่ผ่านการรับรองคุณภาพของ&nbsp;</strong><strong>TCI อยู่ในวารสารกลุ่มที่ 2</strong></li> <li class="show"><strong>ไม่มีค่าใช้จ่ายในการตีพิมพ์</strong></li> <li class="show"><strong>จากประวัติที่ผ่านมาใช้เวลาในการดำเนินการไม่เกิน 3 เดือน/บทความ</strong></li> </ul> Assembly Line Balancing in Semi-trailer Production using Adaptive Genetic Algorithm 2018-12-24T17:30:55+07:00 ณรงค์ศักดิ์ บุญประเสริฐ เชฎฐา ชำนาญหล่อ <p>In semi-trailer production, the mixed assembly line balancing is one of important work to increase productivity. Flat bed &amp; low bed semi-trailer and container chassis semi-trailer are two products in the same family which is assembled in the same line. Then, the assembly line is mixed models implemented for utilizing resources. At the number of workstations is fixed, the averaged cycle time is the objective function of the problem solving, so it could response the several demands today. However, this research problem is well-known as NP-hard, and it is very hard to solve by mathematical models. Thus, the meta-heuristic such as Genetic algorithm (GA) is introduced to balance the mixed-models line of the case study. Moreover, Adaptive genetic algorithms including GA with Rough auto-tuning parameters (GA-RA) and GA with Fine auto-tuning parameters (GA-FA) are developed to apply the same problem and compare with the simple GA. In summarized, the GAs could be used to balance the mixed-models line, and GA-FA is the best effectiveness.</p> 2018-12-24T00:00:00+07:00 ##submission.copyrightStatement## Row Generation Technique to Solve the Problems of Capital Budgeting Allocation under Combinatorial Constraints 2018-12-24T09:31:08+07:00 อภิศักดิ์ วิทยาประภากร เอราวิล ถาวร เริงทิวา ทิพยศักดิ์ พีรยุทธ์ ชาญเศรษฐิกุล <p>This research aims to study capital budgeting allocation under very large combinatorial constraints to consider all alternatives of project investments under limited resources using the row generation technique. The amount of combinatorial constraints in mathematical model of this research is equal to 2<sup>N</sup>-1 where N is the number of projects. If problems of capital budgeting allocation occur due to many projects, many constraints will follow accordingly. As a result, the mathematical model will consist of a very large N and may have difficulty in solving the problems. Therefore, the researchers apply the row generation technique to reduce a number of constraints of capital budgeting allocation down to the number of constraints necessary to find the answers. The results indicate that the row generation technique uses less processing time than the linear programming with over 12 projects. For example, for 20 projects, the processing time to solve the problems by using the linear programming technique is more than 48 hours. On the other hand, for 50 projects, the processing time to solve the problems by using the row generation technique is less than 5 minutes.</p> 2018-12-24T00:00:00+07:00 ##submission.copyrightStatement## Integer Linear Programming Models for Reduction of Number of Types of Packing Boxes 2018-12-24T17:31:01+07:00 ธีระเดช ไหลสุพรรณวงศ์ บุญฤทธิ์ อินทิยศ พันทิพา ทิพย์วิวัฒน์พจนา <p>In packing process, many types of boxes may be used if a factory has several kinds of goods or products. The costs of having many types of boxes can contribute to higher manufacturing costs. However, the costs can be lowered if the number of types of boxes is reduced by substituting one type of box with another available type of box within reasonable criteria. In this paper, we use a criterion that a particular type of box can be replaced by a bigger box (bigger in all dimensions) if the difference in percentage of the length of each side of the box compared with a bigger box does not exceed a specific value. We propose two integer linear programming models which relate to reducing the number of types of boxes under this criterion. The first model is a mixed integer linear programming model which is to minimize the value of the bound of the difference in percentage of the length of each side of the box compared with a bigger box, with the specified number of boxes to be discarded.&nbsp; The second model is a binary integer linear programming model which is to minimize the number of types of boxes when the bound of the difference in percentage of the length of each side of the box compared with a bigger box is specified. Each model can be an option to reduce the number of types of boxes for any industrial packing. Moreover, the numerical examples are given to illustrate the use of the models and to illustrate how their findings can be used in the decision process to reduce the number of the types of boxes.</p> 2018-12-24T10:10:34+07:00 ##submission.copyrightStatement## A Location Analysis of the Fresh Fruit Bunch Collectors in Oil Palm Supply Chain under Zoning Designated Policy: A Case Study of Krabi Province 2018-12-24T17:31:04+07:00 พรนภา หนูทิม วนัฐฌพงษ์ คงแก้ว นิกร ศิริวงศ์ไพศาล กันยา อัครอารีย์ <p>This research aimed to improve the efficiency of the collection and distribution of fresh fruit bunch (FFB) in the supply chain of the upstream oil palm industry, including plantations (farmers), ramps (collectors and distributors), and crude palm oil mills. Based on the zoning designated policy, facility location model and transshipment model were applied to determine the appropriate number and locations of ramps in order to minimize the total transportation cost in the entire supply chain. Three alternative distances between ramps namely 3, 5, and 10 kilometers were formulated and solved by Premium Solver Platform in Microsoft Excel. The calculation results indicated that the 5 kilometers of zoning distance between two ramps with the total of 57 ramps (from formerly 452 ramps) outperformed other scenarios in terms of collection and transportation cost.&nbsp; It reduced the transportation cost from 1,411,410,268 baht a year to 1,180,365,294 baht a year (decreased by 16.37%). Thus, the direction of the zoning designated policy for collecting and distributing FFB could reduce the logistics cost of the supply chain of the upstream oil palm industry.</p> 2018-12-24T17:29:56+07:00 ##submission.copyrightStatement##