• Journal of KIISE:Computer Systems and Theory
• /
• v.29 no.6
• /
• pp.340-345
• /
• 2002

In this paper, we deal with the following facility location problem. Given a set P of n points in the plane, find two (discrete) centers p and q in P that minimize the sum of there distance plus the distance of any other point to the closer center. In this paper, we propose an Ο(n$^2$1ogn)-time algorithm to compute the two centers.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.31 no.2
• /
• pp.19-27
• /
• 2008

This paper addresses determining the location of the distribution centers in a discrete dynamic distribution system. In discrete and finite time horizon, the demands of retailers are dynamic for the periods. Some locations among the retailers can be chosen for the role of the distribution centers at the beginning of each period. The distribution centers have to be located at the location of minimizing logistics cost. Logistics cost factors are the operation cost and the fixed cost of distribution center, and the transportation cost. The distribution centers of minimizing sum of operation cost, fixed cost and transportation cost are determined among retailers in each period for the planning period. A mathematical model was formulated and a dynamic programming based algorithm was developed. A numerical example was shown to explain our problem.

• 제어로봇시스템학회:학술대회논문집
• /
• 1995.10a
• /
• pp.424-427
• /
• 1995

In this paper, a control law based on the receding horizon concept which robustly stabilizes time-varying discrete linear systems, is proposed. A dynamic game problem minimizing the worst case performance, is adopted as an optimization problem which should be resolved at every current time. The objective of the proposed control law is to guarantee the closed loop stability and the infinite horizon $H^{\infty}$ norm bound. It is shown that the objective can be achieved by selecting the proper terminal weighting matrices which satisfy the inequality conditions proposed in this paper. An example is included to illustrate the results..

• Journal of The Korea Institute of Healthcare Architecture
• /
• v.24 no.2
• /
• pp.15-25
• /
• 2018

Purpose: The important things in space plan of a screening center are improving the spatial awareness by space systemization and minimizing the examination time for customers, and reducing the required time of screening work and maximizing the capacity for the screening center. Therefore, we tried to solve the problem of improving spatial awareness and reducing the examination time by using the pedestrian based discrete event simulation at the minimum cost. Methods: We have analyzed the drawbacks and the supplement points by comparing the floor plan at the time of opening and the current floor plan. Based on the analysis, we propose an improved plan which changes the location of the examination rooms and the number of services, and we also verify the improved plan based on simulation analyses. Results: 1) Through the analyses, we derived the drawbacks of the floor plan at the time of opening, and we realized that the current floor plan reflects the drawbacks. 2) The major reasons of the long examination time are the human traffic jam and the occurrence of queues due to unreasonable allocation of services. 3) Through the discrete event simulation analyses, it was possible to specify the place of the queues manually so as to use the given space fairly. 4) Using the discrete event simulation, it was possible to reduce the examination time and to improve the spatial awareness effectively at the minimum cost. Implications: Although the proposed simulation methodology in this paper is an analysis of the existing screening center, we expect that the proposed methodology will be used to develop a more efficient architectural design process by pre-applying the method to the course of designing a screening center and finding the suitability of the proposed method with the matched number of services.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.20 no.2
• /
• pp.159-178
• /
• 1995

Supervisory control is an approach based on formal language. it is used to model and control discrete event systems in which each discrete event process is represented as an automation. A supervisor is a generator that switches control patterns in such a way that a given discrete evenet process behaves in obedience to various constraints. A flexible manufacturing cell (FMC) is one of discrete evenet systems. Functions necessary for the operation of an FMC are characterized by operational components and informational compoments. The operational components can be modeled using the finite state machines and the informational components can be modeled using the abstract formalism which describes supporting operations of the cell controller. In this paper, we addressed function required for FMC control specification, software engineering aspects on FMC control based on supervisory control, a concept of event queue for resolving synchronization problem, and complexity reduction. Based on the mathematical model of an FMC. we synthesized the controller by integrating a supervisor for FMC with control specification that specifies event-driven operation of the cell controller. The proposed control scheme is stable mathematically so that the system always behaves on a controlled way even under the existence of uncontrollable events. Furthermore, using an event queue concept, we can solve a synchronization problem caused by the violation of instantaneity assumption of supervisory control theory in real life situation. And also, we can propotype a control software rapidly due to the modularity of the proposed control scheme.

• Journal of Korean Institute of Industrial Engineers
• /
• v.7 no.2
• /
• pp.19-26
• /
• 1981

A special case of the probabilistic multi-location problem is studied in a two-echelon logistic system for deteriorating items. The objective is to determine the location of the minimum number of supply centers among a discrete set of location sites of supply centers, such that the probability each retailer being covered by some supply center is not less than a specified value. A logistic cost is introduced as performance measure of the system, and leads us to analyze the impact of deterioration rate on the location problem. The results obtained from numerical examples are discussed, which provides effective guidelines that can be used for the logistic managerial decisions.

• Nuclear Engineering and Technology
• /
• v.56 no.2
• /
• pp.520-525
• /
• 2024

The optimization design problem of nuclear reactor radiation shield is a typical multi-objective optimization problem with almost 10 sub-objectives and the sub-objectives are always demanded to be under tolerable limits. In this paper, a design method combining multi-objective optimization algorithms with paralleling discrete ordinate transportation code is developed and applied to shield design of the Savannah nuclear reactor. Three approaches are studied for light-weighted and compact design of radiation shield. Comparing with directly optimization with 10 objectives and the single-objective optimization, the approach by setting sub-objectives representing weight and volume as optimization objectives while treating other sub-objectives as constraints has the best performance, which is more suitable to reactor shield design.

• International Journal of Automotive Technology
• /
• v.3 no.2
• /
• pp.79-88
• /
• 2002

Emergent Collision Avoidance Systems (CAS's) are beginning to assist drivers by performing specific tasks and extending the limits of driver's perception. As CAS's evolve from simple systems handling discrete tasks to complex systems managing interrelated driving tasks, the risk of failure from hidden causes greatly increases. The successful implementation of such a complex system depends upon a robust software architecture. Host of the difficulty in implementing system arises from interconnections between the components. The CAS architecture presented in this paper focuses on these interconnections to mitigate this problem. Moreover, by constructing the GAS architecture through the composition of existing architectural styles, the resulting system will exhibit predictable qualities. Some of the qualities represent limitations that translate into constraints on the system. Others are beneficial aspects that satisfy stakeholder requirements .

• Journal of the Chungcheong Mathematical Society
• /
• v.25 no.2
• /
• pp.367-377
• /
• 2012

The goal of the image restoration is to find a good approximation of the original image for the degraded image, the blurring matrix, and the statistics of the noise vector given. Fast truncated Lagrange (FTL) method has been proposed by G. Landi as a image restoration method for large-scale ill-conditioned BTTB linear systems([3]). We implemented FTL method for the image restoration problem with reflective boundary condition which gives better reconstructions of the unknown, the true image.

• International Journal of Precision Engineering and Manufacturing
• /
• v.2 no.4
• /
• pp.54-60
• /
• 2001

This paper deals with control design method having anticipation delay which is proposed for the discrete nonlinear engine where system dynamics is not accurate. Due to the induction-to-power delay in internal combustion(IC) engine having abrupt torque loss, underdamping and chattering in engine idle speed becomes a serious problem and it could make drivers uncomfortable. For this reason, Three types of the closed-loop controller are developed for the stable engine idle speed control. The inputs of the controllers are an engine idle speed and air conditioning signal. The output of the controllers is an duty cycle to operate the idle speed control valve(ISCV). The proposed controllers will be useful for improving actual vehicles since these shows good test