• Journal of Navigation and Port Research
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• v.29 no.8 s.104
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• pp.747-753
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• 2005

In this paper, as an anti-sway control strategy of container cranes, we investigate a variable structure control in which the moving load follows a given trajectory, whereas both the trolley and hoist controllers achieve their positioning problems. It is crucial, in an automated container terminal, that collisions should be avoided during the transference of containers from one place to another. It is also necessary, in the case of a quay crane, to select suitable loading and unloading trajectories of containers, so that possible collisions with surrounding obstacles are avoided. After a brief introduction of the mathematical model, a robust control scheme (i.e., a second-order sliding mode control that guarantees a fast and precise transference and a suppression of the resulted swing) is presented. Despite model uncertainties and unmodeled actuators dynamics, the swing suppression from the given trajectory is obtained by constraining the system motion on suitable sliding surfaces, which include both the desired path and the swing angle. The proposed controller has been tested with a laboratory-size pilot crane. Experimental results are provided.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.3
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• pp.30-38
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• 2016

Shuttle-Based Storage/Retrieval System (SBS/RS) is relatively new to industry. The system is in the category of Automated Storage/Retrieval System (AS/RS), but it is different in that the SBS/RS uses shuttles as Storage/Retrieval (SR) machine instead using a stacker crane. The shuttles are assigned to each tier on multi-tier system and operated for pick-up or drop-off order. Since the system can handle multiple orders simultaneously, it can provide much higher throughput than that of general AS/RS with single stocker crane. Thus, this new system is well fit to recent tendency of increasing small quantity batch production and orders. One of the drawback of this system is that it needs a lot of investment to set up. The efficient operation of the system would be one of the critical matters to increase economic efficiency of capital investment. In this study, we focused on the dwell point policy for shuttles to find efficient way of operating the system. There are four basic policies for the dwell point and we had simulation-based experiment for two different scenarios based on the speed of the shuttle and inter-arrival time of the loads coming to the system combined with four different policies. As it was mentioned above, this SBS/RS relatively new to the field and there is no such experiment shown on previous research and the study of dwell point policy for this SBS/RS could provide the direct comparison of each policy with different hardware specification; the capability of the system. The policy that achieves most efficient operation among the given environment is proposed and the usability of the system is discussed.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1327-1332
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• 2003

In this paper, an ATC(Automated Transfer Crane) control system is required rapid transportation to get highest productivity with low cost. Therefore, the container paths should be built in terms of the least time and least sway when container is transferred from the initial coordinate to the finial coordinate. So we applied the best-first search method for forming the container path, and calculated the anti-collision path for avoiding collision in its movement to the finial coordinate. And we constructed the neural network two degree of freedom PID (TDOFPID) controller to control the precise navigation. For simulation, we constructed the container profiles so that we analyzed the state of formed path and the performance of TDOFPID controller to the formatted path. Then we compared the performance of ES-tuned PID controller with our proposed controller in terms of trolley position, anti-sway, path change, disturbance, and the load of containers. The computer simulation results show that the proposed controller has better the other on the various conditions.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.1
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• pp.61-72
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• 2005

In this paper, we develop anti-sway control in proposed techniques for an ATC system. The developed algorithm is to build the optimal path of container motion and to calculate an anti-collision path for collision avoidance in its movement to the finial coordinate. Moreover, in order to show the effectiveness in this research, we compared NNP PID controller to be tuning parameters of controller using NN with 2 DOF PID controller. The experimental results for an ATC simulator show that the proposed control scheme guarantees performances, trolley position, sway angle, and settling time in NNP PID controller than other controller. As a result, the application of NNP PID controller is analyzed to have robustness about disturbance which is wind of fixed pattern in the yard. Accordingly, the proposed algorithm in this study can be readily used for industrial applications

• Korean Journal of Construction Engineering and Management
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• v.13 no.4
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• pp.48-59
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• 2012

Gangform, compared to the traditional forms, is a systemized form which can reduce construction duration and cost by the advantage of using it repeatedly. However, transportation and climbing process of the Gangform is highly dependant on the performance of tower crane. Gangform climbing process takes one day out of six to seven days of a structural work cycle. Tower cranes can not be used in other lifting works when they lift the Gangform during the structural work cycle, causing the delay in the construction project. Numerous efforts and researches have been done in domestic and international industry to solve such limitations of Gangform climbing process. Especially, "A Study on the Development of Automatic Gangform Climbing System for Apartment Housing Construction"has suggested a conceptual model which can climb the Gangform system without a tower crane. In this paper, the technical and economical feasibilities of previously proposed Automatic Gangform climbing system are examined by evaluating its structural stability and lifting load reduction effect.

• The Journal of Korean Institute for Practical Engineering Education
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• v.4 no.1
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• pp.80-85
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• 2012

The importance of warehouse is increasing since the role of warehouse in modern industry is changing from concept of storage to concept of circulation which facilitates purchasing, production, storage and distribution activities by induction of information system. In this study, a program is developed using C# for evaluating efficiency of automated storage and retrieval system(AS/RS). A simulation work is done for eight operating schemes under the combination of three conditions, which are storing method, the shape of automatic warehouse and the sequence of command performs, and the moving distance of stacker crane is calculated using the same gateway data. Using this program, the optimal operating scheme can be proposed based on the analyzed results of simulation. This progrm shows the effectiveness and applicability through the simulation work and can be utilized for courses which are related to factory facilities.

• Journal of Intelligence and Information Systems
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• v.14 no.4
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• pp.31-46
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• 2008

A stacking yard of a container terminal is a space for temporarily storing the containers that are carried in or imported until they are carried out or exported. If the containers are stacked in an inappropriate way, the efficiency of operation at the time of loading decreases significantly due to the rehandlings. The remarshaling is the task of rearranging containers during the idle time of transfer crane for the effective loading operations. This paper proposes a method of planning for remarshaling in a yard block of an automated container terminal. Our method conducts a search in two stages. In the first stage, the target stacking configuration is determined in such a way that the throughput of loading is maximized. In the second stage, the crane schedule is determined so that the remarshaling task can be completed as fast as possible in moving the containers from the source configuration to the target configuration. Simulation experiments have been conducted to compare the efficiency of loading operations before and after remarshaling. The results show that our remarshaling plan is really effective in increasing the efficiency of loading operation.

• Journal of Intelligence and Information Systems
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• v.14 no.4
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• pp.103-116
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• 2008

This paper proposes quay crane (QC) scheduling algorithms that determine the working sequence of QCs over ship bays in a container vessel in automated container terminals. We propose two scheduling algorithms that examine the distribution of export containers in the stacking yard and determine the sequence of ship bays to balance the workload distribution among the yard blocks. One of the algorithms is a simple heuristic algorithm which dynamically selects the next ship bay based on the entropy of workloads among yard blocks whenever a QC finishes loading containers at a ship bay and the other uses genetic algorithm to search the optimal sequence of ship bays. To evaluate the fitness of each chromosome in the genetic algorithm, we have devised a method that is able to calculate an approximation of loading time of container vessels considering the workloads among yard blocks. Simulation experiments have been carried out to compare the efficiency of the proposed algorithms. The results show that our QC scheduling algorithms are efficient in reducing the turn-around time of container vessels.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.5
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• pp.473-479
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• 2009

This paper proposes an efficient method to locate the automated guided vehicle (AGV) into a specific parking position using artificial visual landmark and vision-based algorithm. The landmark has comer features and a HSI color arrangement for robustness against illuminant variation. The landmark is attached to left of a parking spot under a crane. For parking, an AGV detects the landmark with CCD camera fixed to the AGV using Harris comer detector and matching descriptors of the comer features. After detecting the landmark, the AGV tracks the landmark using pyramidal Lucas-Kanade feature tracker and a refinement process. Then, the AGV decreases its speed and aligns its longitudinal position with the center of the landmark. The experiments showed the AGV parked accurately at the parking spot with small standard deviation of error under bright illumination and dark illumination.

• Korean Journal of Construction Engineering and Management
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• v.13 no.1
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• pp.53-66
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• 2012

Gangform compared with conventional wood and steel form is systemized form which has a capability to install and dismantle form at a time without repeating to assembly and disassembly small members. Gangform compared with ACS has some problems such as 1) Tower Crane load increase, 2) increase in safety incidence during climbing Gangform, 3) decrease in detachment operation productivity, 4) stop work due to climate impacts, and 5) decrease in labor cost, productivity, quality. A conceptual design model of automated Gangform climbing system is suggested for apartment housing construction to show its technical/economic feasibility and workers' safety while increasing operation productivity and concrete quality.