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Neutrino burst and gravitational wave from supernova explosions
Katsuhiko Sato,Kei Kotake,Keitaro Takahashi,Shin'ichiro Ando 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.1
The time prole and energy spectrum of a neutrino burst from supernovae is greatly modied by the eect of neutrino oscillations. We review how these conversions happen in a supernova mantle and how the burst could be detected by SK (Super-Kamiokande) and SNO (Sudbury Neutrino Observatory). We show that implications for neutrino parameters (mass hierarchy and the mixing angle between mass eigenstate 1; 3), can be obtained if a supernova appears at the Galactic Center. We also discuss the eects of neutrino oscillation on the supernova relic neutrino observations. In the end, we discuss the gravitational radiation from the rotating stellar cores, which will give us the information of the angular momentum distribution for evolved massive stars.
A Flexible Branch and Bound Method for the Job Shop Scheduling Problem
Morikawa, Katsumi,Takahashi, Katsuhiko Korean Institute of Industrial Engineers 2009 Industrial Engineeering & Management Systems Vol.8 No.4
This paper deals with the makespan minimization problem of job shops. The problem is known as one of hard problems to optimize, and therefore, many heuristic methods have been proposed by many researchers. The aim of this study is also to propose a heuristic scheduling method for the problem. However, the difference between the proposed method and many other heuristics is that the proposed method is based on depth-first branch and bound, and thus it is possible to find an optimal solution at least in principle. To accelerate the search, when a node is judged hopeless in the search tree, the proposed flexible branch and bound method can indicate a higher backtracking node. The unexplored nodes are stored and may be explored later to realize the strict optimization. Two methods are proposed to generate the backtracking point based on the critical path of the current best feasible schedule, and the minimum lower bound for the makespan in the unexplored sub-problems. Schedules are generated based on Giffler and Thompson's active schedule generation algorithm. Acceleration of the search by the flexible branch and bound is confirmed by numerical experiment.
Quantifying the Technology Level of Production System for Technology Transfer
Yasuo Yamane,Katsuhiko Takahashi,Kunihiro Hamada,Katsumi Morikawa,Senator Nur Bahagia,Lucia Diawati,Andi Cakravastia 대한산업공학회 2011 Industrial Engineeering & Management Systems Vol.10 No.2
This paper develops a technology level quantification (TLQ) model by utilizing a learning curve. Original learning curve shows the relationship between cumulative number of units and the required time for the unit. On the other hand, in our developed model, the technology level, such as speed of production and quality of the produced items, is expressed as a function of not cumulative number of units but time, for increasing generality. Furthermore, for expressing each learning that consists of conceptual learning and operational learning, S-curve is utilized in our developed model. By fitting the S-curve and/or decomposing into some activities, our TQL model can be applied to approximate organizational and complicated process. Some variations in time and levels, parameters of our developed model are shown. By using the parameters, the procedure to identify our developed model is proposed. Also, the influential factors for the parameters of our developed model are discussed with classifying the factors into technoware, infoware, humanware, and orgaware. The expected technology level is utilized for expecting the capacity of production system, and the expected capacity can be utilized in predicting various changes in the organization and deciding managerial decision about TT. A case study in manufacturing industry shows the effectiveness of the developed model.
Quantifying the Technology Level of Production System for Technology Transfer
Yamane, Yasuo,Takahashi, Katsuhiko,Hamada, Kunihiro,Morikawa, Katsumi,Bahagia, Senator Nur,Diawati, Lucia,Cakravastia, Andi Korean Institute of Industrial Engineers 2011 Industrial Engineeering & Management Systems Vol.10 No.2
This paper develops a technology level quantification (TLQ) model by utilizing a learning curve. Original learning curve shows the relationship between cumulative number of units and the required time for the unit. On the other hand, in our developed model, the technology level, such as speed of production and quality of the produced items, is expressed as a function of not cumulative number of units but time, for increasing generality. Furthermore, for expressing each learning that consists of conceptual learning and operational learning, S-curve is utilized in our developed model. By fitting the S-curve and/or decomposing into some activities, our TQL model can be applied to approximate organizational and complicated process. Some variations in time and levels, parameters of our developed model are shown. By using the parameters, the procedure to identify our developed model is proposed. Also, the influential factors for the parameters of our developed model are discussed with classifying the factors into technoware, infoware, humanware, and orgaware. The expected technology level is utilized for expecting the capacity of production system, and the expected capacity can be utilized in predicting various changes in the organization and deciding managerial decision about TT. A case study in manufacturing industry shows the effectiveness of the developed model.
A Flexible Branch and Bound Method for the Job Shop Scheduling Problem
Katsumi Morikawa,Katsuhiko Takahashi 대한산업공학회 2009 Industrial Engineeering & Management Systems Vol.8 No.4
This paper deals with the makespan minimization problem of job shops. The problem is known as one of hard problems to optimize, and therefore, many heuristic methods have been proposed by many researchers. The aim of this study is also to propose a heuristic scheduling method for the problem. However, the difference between the proposed method and many other heuristics is that the proposed method is based on depth-first branch and bound, and thus it is possible to find an optimal solution at least in principle. To accelerate the search, when a node is judged hopeless in the search tree, the proposed flexible branch and bound method can indicate a higher backtracking node. The unexplored nodes are stored and may be explored later to realize the strict optimization. Two methods are proposed to generate the backtracking point based on the critical path of the current best feasible schedule, and the minimum lower bound for the makespan in the unexplored sub-problems. Schedules are generated based on Giffler and Thompson"s active schedule generation algorithm. Acceleration of the search by the flexible branch and bound is confirmed by numerical experiment.
Component Commonality and Order Matching Rules in Make-to-Forecast Production
Morikawa, Katsumi,Deguchi, Yusuke,Takahashi, Katsuhiko,Hirotani, Daisuke Korean Institute of Industrial Engineers 2010 Industrial Engineeering & Management Systems Vol.9 No.3
Make-to-forecast production is a way to realize high customization and fast responsiveness. This study firstly investigates the effect of introducing a common component in a make-to-forecast production environment. The common component can eliminate a modification step, which is a major cost component in make-to-forecast production. It is illustrated, however, that introducing a versatile component that merely covers several variants is unattractive, and thus adding values to the common component is inevitable in this environment. Secondly, an order-matching rule under the condition that two partially overlapped delivery lead time intervals exist is proposed. The rule considers the effect of matching orders to units that can cover both intervals. An alternative re-matching rule is also developed and examined. Numerical experiments clarify that the proposed rule generally realizes higher contribution ratio and lower percentages of orphans and rejected orders. The proposed re-matching rule increases the average contribution ratio at the expense of increased orphans and order rejections.
A New Worker Policy for Self-Balancing Production Line with Stations
Daisuke Hirotani,Katsumi Morikawa,Katsuhiko Takahashi 대한산업공학회 2011 Industrial Engineeering & Management Systems Vol.10 No.3
In traditional production lines, such as assembly lines, each worker is usually assigned to a particular fixed work, and decreasing the task to master the assigned work is valuated. However, when an imbalance exists between workers" speeds, if a worker delays the overall work in the production line, the production rate of the particular line will also decrease. To avoid this problem, the "Self-Balancing Production Line" was introduced. In this type of production line, each worker is assigned work dynamically, and when specific conditions are satisfied, production remains balanced. Characteristics of these lines that can be preempted at any place have already been analyzed by some researchers. A previous paper examined the situation in which only a single worker can process one machine and cannot preempt processing, and the improved policy of an ordinary self-balancing production line, which specifies which stations workers can process and how workers can behave.This policy achieveda high production rate with only four stations and two workers (Buzacott, 2002). In that paper, worker processing stations and the behavior of a specific worker were limited, andthe paper focused only on specific stations and workers. Therefore, it is not applicable to any worker sequence. In this paper, we focus on other ways to decrease cycle time. In this kind of line, a worker processes at his or her speed. Therefore, if a worker is assigned stations according to his or her speed, the line can decrease cycle time. To do so, we relax the assumptions of this type of line and set a new condition. Under these conditions, we compare our results to the results of previous papers.