• Journal of Intelligence and Information Systems
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• v.13 no.1
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• pp.49-58
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• 2007

MDPDPTW (Multi-Depot Pickup and Delivery Problem with Time Windows) is a typical model among the optimization models based on the pickup and delivery flow in supply chains. It is based on multi-vehicles in multi-depots and does not consider moving vehicles near pickup and delivery locations. In ubiquitous environments, it is possible to obtain information on moving vehicles and their baggage. Providing the proper context from the perspective of moving vehicles and their baggage allows for more effective vehicle routings. This study proposes Integer Programming-based MDPDPTW including the information on moving vehicles and their baggage in a ubiquitous environment: u-MDPDPTW, and shows the viability and effectiveness of u-MDPDPTW through comparative experiments of MDPDPTW and u-MDPDPTW.

• Journal of Korean Institute of Industrial Engineers
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• v.33 no.1
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• pp.33-43
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• 2007

The pickup and delivery problem with time windows generally involves the construction of optimal routeswhich satisfy a set of transportation requests under pairing, precedence, time window, vehicle capacity, andavailability constraints. In this paper, we added some constraints to the problem and adopted an objectivefunction based on number of used vehicles, total travel distance and total schedule duration to consider morerealistic problems. A branch and price algohthm for the problem is proposed and an enumeration method is usedfor the subproblems. The algorithm was tested on randomly generated instances and computational results werereported.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.709-711
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• 2006

According as optical storage becomes high-density, numerical aperture increases. Therefore, the shift characteristic of moving parts in an actuator for optical pickup becomes a critical design factor because of decrease in the tilt margin. The tilt angle is maximized when the position of moving parts is in a diagonal direction within a moving range. This is determined by design of structure and magnetic circuit of an actuator. Previous analysis method only predicts linear characteristics of moving parts. However, the result of shift characteristics of the moving parts considering structural and magnetic circuit's nonlinearity following the every position simultaneously shows us more realistic result. Therefore, we present analysis method considering nonlinearity of moving parts' position through FEM package using coupled-field analysis. Then, we will suggest hereafter a design guide by comparing the above results with experimental ones.

• IE interfaces
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• v.13 no.3
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• pp.462-470
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• 2000

This paper is concerned with a vehicle routing model to assist in scheduling palletized cargo pickup and delivery so called the pickup and delivery problem with advance requests in a 2-echelon supply-chain system. In this study vehicles is dispatched and routed so that each request is picked up or delivered at its original and to its destination. The model provides point-to-point transportations based on advance requests. The assignment algorithm is developed and designed for using with on-line computers and it immediately provides arrangements to be made at the time requested. This algorithm also provides the best scheduling solutions and alternatives for both to system operators and requesters. According to this algorithm, we developed computer programs and show the sample results.

• Journal of Mechanical Science and Technology
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• v.17 no.11
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• pp.1616-1627
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• 2003

This paper describes a mini linear optical pickup actuator. To reduce the size, inner yokes are designed to guide the mover and outer yokes of permanent magnets are removed. Magnetic circuit method is used to determine the thrust force. Virtual path method is proposed to analyze the open magnetic circuit analysis. The magnetic circuit of the proposed actuator can be a closed circuit due to the virtual path model of the outer magnetic flux. The validity of virtual path method is evaluated by comparing to the FEM analysis. Structural vibration is investigated using FEM and the design of the mover is modified to improve the vibration characteristic. Dynamic characteristic experiments shows that the performance of the proposed actuator is enough to be used as a coarse and fine seeking actuator simultaneously and the thrust force margin for loading a focusing actuator is guaranteed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.565-569
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• 2002

To improve the driving sensitivity of an optical pickup actuator for high density and high speed drive, we present a new actuator design using multipolar flux-density distribution by magnetic materials and Nd-Fe-B sintered magnets. We expect this actuator to use in 3-axis actuator for tilt compensation as well as conventional 2-axis actuator. The electromagnetic field analysis applying 3-D FEM was performed and several samples were actually tested. From comparing simulated data with experimental results, we verified the accuracy of the simulation and the superiority of the presented method.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.771-773
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• 2001

In this paper, three dimensional Equivalent Magnetic Circuit Method(3-D EMCN method) a numerical analysis method which supplements to magnetic equivalent circuit adding numerical technique, is proposed for analysis Optical Pickup Actuator. (3) This method provides better characteristics both in precision of the analysis and in computation time than other analysis method such as three-dimensional Finite Element Method. We choose the simple 2-magnet moving coil type pickup actuator model and verify upper yoke effect using this method.

• Journal of the Optical Society of Korea
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• v.16 no.1
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• pp.29-35
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• 2012

We propose a subpixel scale elemental image generation method to correct the errors created by finite display pixel size in integral imaging. In this paper, two errors are mainly discussed: pickup-and-display mismatch error and mismatch error between pixel pitch and lens pitch. The proposed method considers the relative positions between lenses and pixels in subpixel scale. Our proposed pickup method calculates the position parameters, generates an elemental image with pixels completely inside the lens, and generates an elemental image with border pixels using a weighted sum method. Appropriate experiments are presented to verify the validity of the proposed method.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.12
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• pp.109-119
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• 2002

In this paper, mechanism design of optical pickup actuator for fast access is proposed. This actuator is composed of moving magnet type actuator and moving coil type actuator for tracking and fine motion, respectively. Moving magnet type tracking actuator is configurated by two permanent magnets and four air-core solenoids. Additional damper by induced current in tracking actuator can reduce the transient vibration between the coarse seeking servo and fine seeking servo. Variable stiffness can be acquired by applying current to air-core solenoid simply. This actuator can achieve fast access by these additional damper and stiffness. Performance of this actuator is predicted through the FEM, simulation and simple experiment. Settling time for transient vibration is reduced to 14.7% according to simulation result.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.358.2-358
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• 2002

To improve the driving sensitivity of an optical pickup actuator for high density and high speed drive, we present a new actuator design using multipolar flux-density distribution by magnetic materials and Nd-Fe-B sintered magnets. We expect this actuator to use in 3-axis actuator fur tilt compensation as well as conventional 2-axis actuator. The electromagnetic field analysis applying 3-D FEM was performed and several samples were actually tested. From comparing simulated data with experimental results, we verified theaccuracy of the simulation and the superiority of the presented method.