• 대한산업공학회지
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• 제19권2호
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• pp.65-74
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• 1993

In this paper, a two-echelon production-inventory model is developed which integrates the production scheduling problem of the multi-products produced on a single facility and the inventory problem of the related raw materials. The setup costs of the final products are assumed to be dependent on the production sequence. The aim is to determine simultaneously the production cycle time and the production sequence of the final products, and the procurement cycle times of the raw materials. For the model developed, a solution algorithm is suggested and illustrated with a numerical example. And the result is compared with those obtained by two separate subproblems.

• 한국CDE학회논문집
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• 제2권1호
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• pp.19-27
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• 1997

This paper presents rough cut tool path planning for the fewer-axis machine consisting of a three-axis CNC machine and a rotary indexing table. In the problem dealt with in this paper, the tool orientation is "intermediately" changed, distinguished from the conventional problem where the tool orientation is assumed to be fixed. The developed rough cut path planning algorithm tries to minimize the number of tool orientation (setup) changes together with tool changes and the machining time for the rough cut by the four procedures: a) decomposition of the machining area based on the possibility of tool interference (via convex hull operation), b) determination of the optimal tool size and orientation (via network graph theory and branch-and bound algorithm), c) generation of tool path for the tool and orientation (based on zig-zag pattern), and d) feedrate adjustment to maintain the cutting force at an operation level (based on average cutting force). The developed algorithms are validated via computer simulations, and can be also used in pure fiveaxis machining environment without modification.

• 한국초전도ㆍ저온공학회논문지
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• 제1권2호
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• pp.30-36
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• 1999

Superconductors are dissipative when exposed to time-varying magnetic fields. To analyze the AC characteristics of a superconductor, one usually needs to know magnetization curves of it. Good magnetization curves can be obtained only in homogeneous magnetic filed. In This paper, we report the setup and test results of a magnetization measurement system, which consists mainly of frequency-variable power supply and homeogenous magnet with 7-cm long air gap. Special emphasis are foused on the design and fabrication of the magnet, which aims to give background magnetic fields, and on the overall characteristics of the system.

• 대한기계학회논문집A
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• 제24권3호
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• pp.769-776
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• 2000

RP(Rapid Prototyping) technology is gaining its popularity in building a prototype in all industries. SLS(Slective Laser Sintering) is one of RP technologies, which is focused on tooling processes as well as three dimension solid model. There are several factors, the length and the cross-sectional area of a part, that have an effect on build setup in SLS process. In this paper, the computation on geometrical relationship is used to slice STL file and to estimate these factors. Based on these values, the build setup parameters such as the heating temperature, the laser power, and the powder cartridge feed rate are determined by neural network approaches. The test results show that the computation time is saved and the neural network approach is able to apply to get the optimal parameters of build process within an acceptable error rate.

• 전력전자학회논문지
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• 제7권5호
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• pp.465-471
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• 2002

본 논문에서는 산업용 서보 구동 시스템의 새로운 PID 속도 제어기를 제안한다. 제안된 속도 제어기는 전류 제어 루프의 주파수 대역에 의해서 속도 제어 루프의 대역폭이 자동적으로 결정되고, 속도제어 루프의 지연을 고려하여 제어기 이득이 자동적으로 선정이 된다. 제안된 설계 방식은 그 자체로 최소한의 오버슈우트와 진동을 갖는 빠른 속도 응답을 실현한다. 또한, 제안된 방식은 기존의 직렬 구조 형태의 위치제어기에 간단히 적용할 수 있다.

• Journal of Power Electronics
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• 제9권2호
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• pp.207-214
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• 2009

This paper presents a modem approach for speed control of a PMSM using the Particle Swarm Optimization (PSO) algorithm to optimize the parameters of the PI-Controller. The overall system simulated under various operating conditions and an experimental setup is prepared. The use of PSO as an optimization algorithm makes the drive robust, with faster dynamic response, higher accuracy and insensitive to load variation. Comparison between different controllers is achieved, using a PI controller which is tuned by two methods, firstly manually and secondly using the PSO technique. The system is tested under variable operating conditions. Implementation of the experimental setup is done. The simulation results show good dynamic response with fast recovery time and good agreement with experimental controller.

• 경영과학
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• 제24권1호
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• pp.35-43
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• 2007

Minimizing the total number of setup changes of a machine increases the throughput and improves the stability of a production process, and as a result enhances the product qualify. In this context, we consider a new product-mix problem that minimizes the total number of setup changes while producing the required quantities of a product over a given planning horizon. For this problem, we develop a mixed integer programming model. Also, we develop an efficient heuristic algorithm to find a feasible solution of good quality within reasonable time bounds. Computational results show that the developed heuristic algorithm finds a feasible solution as good as the optimal solution in most test problems.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.1001-1006
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• 2004

Railroad disasters are frequently occurred by man-made causes or natural causes. In general, man-made causes are illegal construction practices, deterioration with the lapse of time and railroad crossing accidents, and natural causes are rainfall. snow, wind, earthquake, etc. Of cause, railroad disasters by man-made causes are prevented from keeping the safety principle, constructing multi-level crossing, securing enough men of ability and financial resources and making a thorough check using equipments with high capacity. And railroad disasters by natural causes are also minimized by construction of disaster prevention facilities, introduction and operation of general disaster prevention system and reasonable train passage control. Therefore, to setup the criterion of train passage control for train safety at railroad bridge under heavy rainfall, risky factors, national and oversea criteria under such circumstances are reviewed and a scheme to setup the criterion is suggested.

• 대한산업공학회지
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• 제13권1호
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• pp.1-10
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• 1987

This paper deals with a single-facility multiproduct lot-size model requiring consideration of setup costs. Each product is demanded at the constant rate per unit time in the next particular period. Due to the limitation of the production capacity, some productions of total demand requirement in that period must be pre-produced. The aim of this project is to determine when and how much of each product to make in order to minimize the total setup costs and inventory carrying-costs of all products. Also this paper contains the further realistic treatment of inventory carrying-costs.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권2호
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• pp.119-128
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• 2018

A numerical method is proposed to simulate level ice interaction with ship in transverse and longitudinal directions in time domain. A novel method is proposed to simulate non-symmetric transverse force in a stochastic way. On the basis of observations from the model tests, the simulation of longitudinal force combines the ice bending force acting on the waterline, submersion force below the waterline and ice friction forces caused by transverse force and ice floes rotation amidships. In the simulations the ship was fixed and towed through an intact ice sheet at a certain speed. The setup of the numerical simulation is similar to the ice tank setup as much as possible. The simulated results are compared with model tests data and the results show good agreement with the measurement.