• International Journal of Precision Engineering and Manufacturing
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• v.3 no.1
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• pp.66-75
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• 2002

The crane operation used fur transporting heavy loads causes a swinging motion with the loads due to the crane\`s acceleration and deceleration. This sway causes the suspension ropes to leave their grooves and can cause serious damage. Ideally, the purpose of a crane system is to transport loads to a goal position as soon as possible without any oscillation of the rope. Currently, cranes are generally operated based on expert knowledge alone, accordingly, the development of a satisfactory control method that can efficiently suppress object sway during transport is essential. The dynamic behavior of a crane shows nonlinear characteristics. When the length of the rope is changed, a crane becomes a time-varying system thus the design of an anti-sway controller is very difficult. In this paper, a nonlinear dynamic model is derived for an industrial overhead crane whose girder, trolley, and hoister move simultaneously. Furthermore, a fuzzy logic controller, based on expert experiments during acceleration, constant velocity, deceleration, and stop position periods is proposed to suppress the swing motion and control the position of the crane. Computer simulation is then used to test the performance of the fuzzy controller with the nonlinear crane model.

• The Journal of Information Systems
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• v.15 no.1
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• pp.169-189
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• 2006

Recently, many companies are trying to survive in a competitive business environment and they employ various kinds of information systems. Business Process Management (BPM) system is a software system that integrated enterprise information systems based on processes, which is considered an essential element for managing inner and outer processes. Though the BPM system has been applied to major processes only so far, companies begin to extends target processes applied into enterprise wide. In such settings, not only exact but also efficient management of processes is required. The efficiency of BPM has two perspectives: one is the performance of users that handle assigned tasks, and the other is the performance of the Business Process (BP) engine that carries out execution of processes. In this paper, in order to deal with the seconde perspective, we develop Drum, Buffer, and Rope (DBR) method, which have been considered innovative Theory of Constraint (TOC) method in manufacturing domain, for efficient management of processes. A new method, BP-DBR, has been developed, and we show that it is effective for business processes. The effectiveness of the method has been proved in terms of efficiency measures such as average process completion time and average number of completed processes, through a series of simulations on real banking processes.

• International Journal of Fluid Machinery and Systems
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• v.8 no.2
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• pp.84-93
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• 2015

The computational cost is expensive for CFD-DEM simulation, a larger time step and a simplified CFD-DEM model can be used to accelerate the simulation. The relationship between stiffness and overlap in non-linear Hertzian model is examined, and a reasonable time step is determined by a new single particle test. The simplified model is used to simulate dilute pneumatic conveying with different types of bends, and its applicability is verified by compared with the traditional model. They are good agreement in horizontal-vertical case and vertical-horizontal case, and show a significant differences in horizontal-horizontal case. But the key features of particle rope formed in different types of bends can be obtained by both models.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2000.11a
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• pp.159-167
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• 2000

During the operation of crane system in the container yard, it is necessary to control the crane trolley position so that the swing of the hanging container is minimized. Recently an automatic control system with high speed and rapid transportation is required. Therefore, we designed a controller to control the crane system with disturbances and weight change. In this paper, we present the neural network two degree of freedom PID controller to control the swing motion and trolley position. Then we executed the computer simulation to verify the performance of the proposed controller and compared the performance of the neural network PID controller with our proposed controller in terms of the rope swing and the precision of position control. Computer simulation results show that the proposed controller has better performances than neural network PID with disturbances.

• Journal of Korean Institute of Industrial Engineers
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• v.43 no.1
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• pp.12-18
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• 2017

This study presents a plant concept design for a smart factory which is mainly targeted to machine airplane parts. The plant layout is based on the TOC-DBR approach together with autonomous distributed factory control considered, while discrete event simulation is also performed in order to validate its layout. The resulting layout and its procedure turn out to be quite a useful guideline in realizing those smart factories especially for machining-oriented manufacturing industries.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.142-142
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• 2000

During the operation of crane system in container yard, it is necessary to control the crane trolley position so that the swing of the hanging container is minimized. Recently an automatic control system with high speed and rapid transportation is required. Therefore, we designed a controller to control the crane system with disturbances. In this paper, Ive present the neural network two degree of freedom PID controller to control the swing motion and trolley position. Then we executed the computer simulation to verify the performance of the proposed controller and compared the performance of the neural network PID controller with our proposed controller in terms of the rope swing and the precision of position control . Computer simulation results show that the proposed controller has better performances than neural network PID with disturbances.

• Korean Journal of Computational Design and Engineering
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• v.15 no.1
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• pp.70-83
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• 2010

Recently, floating cranes are mainly used to erect heavy blocks or cargos for constructing ships in many shipyards. It is important to estimate the dynamic motion of the heavy cargo suspended by a floating crane and the tension of the wire ropes between the floating crane and the heavy cargo. In this paper, the coupled dynamic equations of motion are set up for considering the 6 degree-of-freedom floating crane and the 6-degrees-of-freedom heavy cargo based on multibody system dynamics. Depending on the cargo weight, the motion of the floating crane would be changed to nonlinear state. The nonlinear terms in the equation of motion are considered. In addition, the nonlinear hydrostatic force, the linear hydrodynamic force, wire rope force, mooring force and gravity force are considered as the external forces. As the result of this paper, we analyze the engineering effect for erecting the heavy cargo by using the floating crane.

• Ocean and Polar Research
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• v.41 no.1
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• pp.19-34
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• 2019

The present study obtained universal mathematical models of all elements and characteristics regarding hook and line fishing systems. To describe the hook and line fishing systems on site we used three kinds of coordinate systems: the earth based coordinate system, natural coordinate system, and flow (velocity) coordinate system. Mathematical models presented in this article allow us to define the shape of the fishing gear, the tension of the rope at different points, hydrodynamic resistance, diameter of the hook's wire, immersion depth of the fishing hooks, distance from hooks to the ground and the required lifting force of the floats. These models allow for the performance of computer simulations regarding any kinds of hook and line gears in still water or water where flow occurs.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.4
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• pp.299-307
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• 2016

This study aims to investigate effects of the length of the buoy and sand bag line on the loss of webfoot octopus pot. A numerical modeling and simulation was carried out to analyze the process that the pot gear affected by wave using the mass spring model. Through the simulation, tensions of sand bag line under various condition were investigated by length of buoy and sand bag line. The drag force and coefficient k of an artificial shell used in the webfoot octopus pot was obtained from an experiment in a circular water channel, and the coefficient k was applied to the simulation. To verify the accuracy of the simulation model, a simple test was conducted into measuring a rope tension of a hanging shell under flow. Then, the test result was compared with the simulation. The lengths of the buoy line in the simulation were 1.12, 1.41, 1.80, 2.23, 2.69, and 3.17 times of water depth. The lengths of sand bag line were 10, 20, 30, and 40 meters, and conditions of water depth were 8, 15, 22 meters. 4 meter height and 8 second period of wave were applied to all simulations. As a results, the tension of the sand bag line was decreased as the buoy and sand bag line were increased. The minimum tension of the sand bag line was appeared in conditions that the length of the buoy line is twice of water depth and the sand bag line length is over 40 meters (except in case of depth 8 meters.).

• Proceedings of the Korea Association of Information Systems Conference
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• 2003.11a
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• pp.55-63
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• 2003

Workflow Management System (WFMS) is a software system to support an efficient execution, control and management of complex business processes. Since traditional commercial systems mainly focus on automating processes, they don't have methods for enhancing the task performer's efficiency. In this paper, we propose a new method of executing business processes more efficiently in that a whole process is scheduled considering the degree of the participants' workload. The method allows managing the largest constraints among constituent resources of the process. We utilize DBR scheduling techniques to develop the method. We first consider the differences between workflow process models and DBR application models, and then develop the modified drum, buffer and rope. This leads us to develop WF-DBR (WorkFlow-DBR) that can control the proper size of the task performers' work list and arrival rate of process instances. Use of WF-DBR improves the efficiency of the whole process as well as the participants' working condition. We then carry out a set of simulation experiments and compare the effectiveness of our approach with that of scheduling techniques used in existing systems.