• 한국정밀공학회지
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• 제18권8호
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• pp.48-53
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• 2001

In order to increase productivity and efficiency, high-speed rotating machines become popular these days. The high-speed rotating machine is likely to vibrate and cause machine failure even though it has small unbalance. Therefore, a balancing technique is studied in this paper. Off-line balancing methods are inadequate to solve unbalance vibration problem occurring in the field due to flexible rotor effect, faster tool change, and shorter spin-up and down, etc. An active balancing is suggested to allow re-balancing of the entire rotating assembly in the machine when a tool is changed. This paper shows how to identify the dynamics of the system using influence coefficient and suggest an active balancing technique based on influence coefficient method for high-speed spindle system.

• 한국경영과학회지
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• 제19권2호
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• pp.217-228
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• 1994

This paper presents a new integer formulation (Type III ALB) for a single model assembly line balancing problem. The objective of the formulation is to minimize the total idle time, which is defined as the product of the number of work stations and the cycle times minus the total work content. This formulation considers currently existing Type I (minimizing the number of work stations for a given cycle time) and type II (minimizing the cycle time for a given number of work stations) formulations as its special cases and provides the global minimum solutions of the cycle time and the number of work stations. This information would be of great value to line designers involved in designing new assembly lines and rebalancing old lines under flexible conditions. Solution methods based on combination of Type I and Type II approaches are also suggested and compared.

• 한국경영과학회지
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• 제23권2호
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• pp.83-101
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• 1998

Assembly U-lines are increasingly accepted in industry, especially just-in-time production systems, for the efficient utilization of workforce. In this paper, we present an integer programming formulation and a branch-and-bound method for balancing the U-line with the objective of minimizing the number of workstations with a fixed cycle time. In the mathematical model, we provide the method that can reduce the number of variables and constraints. The proposed branch-and-bound method searches the optimal solution based on a depth-first-search. To efficiently search for the optimal solutions to the problems, an assignment rule is used in the method. Bounding strategies and dominance rules are also utilized. Some problems require a large amount of computation time to find the optimal solutions. For this reason. some heuristic fathoming rules are also proposed. Extensive experiments with test-bed problems in the literature are carried out to show the performance of the proposed method. The computational results show that our method is promising in solution quality.

• Journal of Power Electronics
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• 제12권4호
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• pp.567-577
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• 2012

This paper introduces a new scheme to balance the DC bus voltages of a cascaded H-bridge converter which is used as a Distribution Static Synchronous Series Compensator (D-SSSC) in electrical distribution network. The aim of D-SSSC is to control the power flow between two feeders from different substations. As a result of different cell losses and capacitors tolerance the cells DC bus voltage can deviate from their reference values. In the proposed scheme, by individually modifying the reference PWM signal for each cell, an effective balancing procedure is derived. The new balancing procedure needs only the line current sign and is independent of the main control strategy, which controls the total DC bus voltages of cascaded H-bridge. The effect of modulation index variation on the capacitor voltage is analytically derived for the proposed strategy. The proposed method takes advantages of phase shift carrier based modulation and can be applied for a cascaded H-bridge with any number of cells. Also the system is immune to loss of one cell and the presented procedure can keep balancing between the remaining cells. Simulation studies and experimental results validate the effectiveness of the proposed method in the balancing of DC bus voltages.

• International Journal of Contents
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• 제3권1호
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• pp.9-13
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• 2007

This paper proposes a policy on efficient load balancing that can reduce the network game server load burdened by surging number of users. The study adopted a contents-based clustering technique. Recently, skyrocketing number of clients in on-line games causes overloads on specific game servers, and the consequent server-instability brings the worst situation: a server failure. To cope with this problem, one can install more high-powered servers or be equipped with back-up servers, which is often inefficient in terms of cost performance. To solve this problem, the present study examined the technology enhancing the performance and efficiency of game servers by reducing the loads of specific game servers. In doing this, this study used the clustering technology to compose game servers classified by their contents and carried out appropriate load balancing to numerous clients with load balancers in each region.

• 한국인터넷방송통신학회논문지
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• 제10권4호
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• pp.157-162
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• 2010

Cart-pole 균형 문제는 유전자 알고리즘, 인공신경망, 강화학습 등을 이용한 제어 전략 분야의 표준 문제이다. 본 논문에서는 cart-pole 균형문제를 해결하기 위해 실시간 강화 학습을 이용한 접근 방법을 제안하였다. 본 논문의 목적은 cart-pole 균형 문제에서 OREL 학습 시스템의 학습 방법을 분석하는데 있다. 실험을 통해, 본 논문에서 제안한 OREL 학습 방법은 Q-학습보다 최적 값 함수에 더 빠르게 접근함을 알 수 있었다.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1995년도 춘계공동학술대회논문집; 전남대학교; 28-29 Apr. 1995
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• pp.72-72
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• 1995

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1996년도 춘계공동학술대회논문집; 공군사관학교, 청주; 26-27 Apr. 1996
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• pp.737-740
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• 1996

This paper suggests a boltzman machine neural network model to determine model input sequences in line balancing process of mixed model assembly line. We first present a proper energy function, next determine the value of parameters using simulation process.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1996년도 춘계공동학술대회논문집; 공군사관학교, 청주; 26-27 Apr. 1996
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• pp.469-469
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• 1996

• 한국인터넷방송통신학회논문지
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• 제22권2호
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• pp.89-96
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• 2022

본 논문은 NP-난제로 알려진 단일모델 교차혼합 조립라인 균형문제에 대해 휴리스틱 알고리즘을 제안하였다. 조립라인 균형문제는 주로 메타휴리스틱 방법들을 적용하고 있는 추세로 다항시간의 정확한 해를 찾는 알고리즘이 제안되지 않고 있어 실무에 적용하기가 매우 어렵다. 제안된 알고리즘은 주어진 총 조립시간 W와 순환시간 c에 대해 m^* = ⌈W/c⌉의 최소 작업자수와 c^* = ⌈W/m^*⌉의 목표 순환시간을 구하고, i=1,2,…,m^* 개의 작업대에 T_i=c^* ±α≤ c가 되도록 양방향의 공정들을 배정하는 양방향 군집방법을 적용하였다. 7개의 다양한 실험 데이터에 적용한 결과 제안된 양방향 군집 알고리즘은 타 방법들과 동일한 성능을 보였다.