• Industrial Engineering and Management Systems
• /
• v.6 no.2
• /
• pp.106-118
• /
• 2007

This paper present a new optimization model to generate aggregate production planning by considering electric cost. The new Time Of Switching (TOS) electric type is introduced by switching over Time Of Day (TOD) and Time Of Use (TOU) electric types to minimize the electric cost. The fuzzy demand and Dynamic inventory tracking with multiple plant capacity are modeled to cover the uncertain demand of customer. The constraint for minimum hour limitation of plant running per one start up event is introduced to minimize plants idle time. Furthermore; the Optimal Weight Moving Average Factor for customer demand forecasting is introduced by monthly factors to reduce forecasting error. Application is illustrated for multiple cement mill plants. The mathematical model was formulated in spreadsheet format. Then the spreadsheet-solver technique was used as a tool to solve the model. A simulation running on part of the system in a test for six months shows the optimal solution could save 60% of the actual cost.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1993.10a
• /
• pp.565-583
• /
• 1993

In order to reduce the production cost and improve the quality of dairy feed, several dairy feed mill model suitable for Korean farm size are developed. Also, capital requirement and operating costs of the model mill are analyzed. And these analyzed data are compared with the commercial feed production cost, in order to test whether the model mills are suitable or not in Korean dairy farm. Also optimum model is recommended depending on size of dairy farm. As a result, developed model mill(TMR) is very useful in Korea dairy farm not only reduce production cost up to 78% but also improve the qualities.

• ETRI Journal
• /
• v.35 no.6
• /
• pp.1148-1151
• /
• 2013

We propose a way to measure the absorber reflectivity at a low cost. Only one simple antenna with a small radiating aperture and a frequency-domain instrument are utilized. The previously used equation for calculating the reflectivity of an absorber is inaccurate, and, therefore, a new equation is derived based on multiple reflection analysis and three test models. Notably, the reflection coefficient of the antenna is included in the derived equation. The accuracy of the proposed method is proven through simulation and measurements. It can be easily applied to a product examination by absorber manufacturers and customers owing to its advantages of simplicity, cost effectiveness, and non-cutting examination.

• The Journal of Information Systems
• /
• v.14 no.2
• /
• pp.155-172
• /
• 2005

Securities companies which faced with severe competition should not only attract new customers but also retain their on-line customers. This study examines the factors affecting loyalty of on-line stock trading customers. The research model based on the previous studies was established and the research hypotheses were generated. The test results based on the data gathered from 87 users of on-line stock trading services show that user satisfaction, learning cost, transaction fees, and reputation influence customer loyalty. User satisfaction, learning cost and reputation are positively related to customer loyalty, whereas transaction fee is negatively related to customer loyalty. The results also support that information quality and system quality are positively related to user satisfaction. The hypothesis that transaction fee is related to user satisfaction is not supported. There is no significant information to say that security risk is related to user satisfaction. It is considered that the study results may help managers to increase customer retention.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2011.11a
• /
• pp.133-134
• /
• 2011

While researches related with construction automation have dramatically increased, a Robot-based Automatic Construction system (RCA system) has developed for high-rise buildings in Korea. At the aspect that wide adoption of the RCA system is dependent on economic efficiency comparing with a conventional method, feasibility study on the RCA system should be implemented. However, due to practical limitations, the RCA system has tested to a seven story building. Based on the test results, this study implements a cost/benefits analysis to a simulated forty story building in order to derive more reliable data on the RCA system's practicability.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2003.05a
• /
• pp.8-13
• /
• 2003

This paper considers a continuous-review two-echelon inventory control problem with one-to-one replenishment policy incorporated and with lost sales allowed where demand arrives In a stationary Poisson process The problem Is formulated using METRIC-approximation in a combined approach of pricing and (S-1.S) Inventory policy, for which an iterative solution algorithm is derived with respect to the corresponding one-warehouse multi-retailor supply chain. Specifically, decisions on retail pricing and warehouse inventory policies are made in integration to maximize total profit in the supply chain. The objective function of the model consists of sub-functions of revenue and cost (holding cost and penalty cost). To test the effectiveness and efficiency of the proposed algorithm, numerical experiments are performed The computational results show that the proposed algorithm is efficient and derives quite good decisions

• Journal of Korean Society of Water and Wastewater
• /
• v.14 no.1
• /
• pp.76-83
• /
• 2000

This research is about wastewater containing non-biodegradable TDI(Toluene Diisocyanate) that is treated by the activated carbon adsorption method. In the case of the Fenton oxidation process being applied to the existing process, optimal pH, reaction time, chemical dosing amount, removal rate, and cost were investigated. A pilot plant test was applied after finding optimal conditions with lab experiments. The optimal conditions were pH 3~5(COD removal rate 84~88%) and reaction time 30min~1hr. In higher $H_2O_2$ dosing amount, COD removal rate was a little higher. But there was little difference in the removal rate according to $FeSO_4{\cdot}7H_2O$ dosing amount. Treatment cost was economical in the case of the Fenton oxidation process being operated earlier than activated carbon adsorption system. But chemical dosing point, chemical mixing effect, chemical dosing amount, removal rate, and the cost of facility and others must be considered in practical process.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1990.04a
• /
• pp.186-194
• /
• 1990

Just-In-Time production is to keep the kanban system. When production managers implement and operate successfully the system in the multi-Line, multi-stage production setting, it is very important to determine the number of kanbans in deterministic kanban system under consideration with relevant factors as well as with cost. In concrete, we discuss about following factors in kanban system and provide a model formulating the multi-objective goal programming : Demand, stock on hand in process, Inventory cost and Labor cost, Vendor's suppling capacity, Work Load. Finally we analyze several numerical examples in order to test the model and attempt to expand the model in general case.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1991.10a
• /
• pp.405-421
• /
• 1991

In this paper, faults existing in a software system is classified into three types; simple, degenerative and regenerative faults. The reliability functions and failure rates of both a software module and system which have a mixture of such faults are obtained and the expected number of failures in the system after time T is also derived. Using the formulas obtained, a cost-reliability model and an efficient algorithm for optimal software release time are proposed via nonlinear programming formulation ; minimizing the total test cost with constraints on the failure rates of each module. Application of this model to several cases are presented and it appears to be more realistic.

• Management Science and Financial Engineering
• /
• v.17 no.2
• /
• pp.1-21
• /
• 2011

This paper considers an integrated inventory-distribution system with a fleet of heterogeneous vehicles employed where a single warehouse distributes a single type of products to many spatially distributed retailers to satisfy their dynamic demands. The problem is to determine order planning at the warehouse, and also vehicle schedules and delivery quantities for the retailers with the objective of minimizing the sum of ordering cost at the warehouse, inventory holding cost at both the warehouse and retailers, and transportation cost. For the problem, we give a Mixed Integer Programming formulation and develop a Lagrangean heuristic procedure for computing lower and upper bounds on the optimal solution value. The Lagrangean dual problem of finding the best Lagrangrean lower bound is solved by subgradient optimization. Computational experiments on randomly generated test problems showed that the suggested algorithm gives relatively good solutions in a reasonable amount of computation time.