• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.3
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• pp.163-173
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• 2001

The dynamic behavior characteristics of a small fishing crane for inshore and coastal fishing vessels was experimentally analyzed in order to improve the fishing operation and to reduce considerably manual work of fisherman. The small fishing crane was designed to be controlled electro-hydraulically by means of proportional valves and solenoid valves, and also to be controlled the speed of each operation. The dynamic behavior characteristics was investigated by measuring the changes of parameters such as oil pressure, swing angle of load, load tension, the lifting angle and the swing angle of crane arm when the arms extended in a side way was given a test load. The results obtained are summarized as follows: 1. The designed small fishing crane can be proportionally controlled by means of proportional valves and rapidly by operating the solenoid valves, respectively. The capacity, turning angle, maximum reach of crane were 2 T-M, $180^\circ$, 3.7m, respectively. 2. The vertical change of crane arm on the extension of lifting cylinder was $1.2^\circ$/cm, and the swing speed of crane arm due to the extension of swing cylinder by on/off operations of solenoid valves was $15^\circ$/sec, with the swing period of 1.4 sec and the angle fluctuation of $\pm$11.0$^{\circ}$. 3. When changing simultaneously the horizontal and vertical positions of the lifting load by on/off operations of solenoid valves, the swing and lifting speeds of crane arm were $4.46^\circ$/sec and $6.4^\circ$/sec, respectively. 4. The movements of the designed crane were particularly smooth as they are controlled with the aid of proportional valves than by means of solenoid valves.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.178-183
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• 2008

A robot crane truck is being developed by the Bridge Inspection Robot Development Interface(BRIDI) for an automated and/or teleoperated bridge inspection. At the end of the telescoping boom allows the operator to scan the bridge structure under the deck trough the camera. Boom vibration induced by wind and deck movement can cause serious problems in this scanning system. This paper presents a control system to mitigate such vibration of the robot boom In the proposed control system an actuator is installed at the end of the working boom. This control system is studied using a mathematical model analysis with LQ control algorithm and a scaled model test in the laboratory. The study indicates that the proposed system is efficient for the vibration control of the robot booms, thereby demonstrating its immediate applicability in the field.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1998.10a
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• pp.309-313
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• 1998

Delay time of receiving and delivery is one of important factors that should be considered in the evaluation of the customer service level of a container terminal. In this study, dispatching rules are tested with the objective of minimizing the service delay time for arriving outside trucks. A dynamic programming model is suggested for a static dispatching problem in which all the truck arrivals are known in advance. In order to overcome the excessive computational time of the dynamic programming technique, several heuristic rules are suggested that can be applied in practices. A simulation study is carried out to test the performances of the heuristic rules.

• Special Issue of the Society of Naval Architects of Korea
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• 2009.09a
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• pp.97-106
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• 2009

Many production methods are tried to enhance the productivity efficiency. Parallel connected floating cranes are one of the examples to lift mega-blocks quickly and efficiently. However, a general operation manual to operate parallel connected floating cranes and a method to consider risks during lifting operation are not confirmed. And if each floating crane is operated by itself, it is very hard to cooperate. Therefore, Synchronized operation system is installed to control parallel connected floating cranes simultaneously and to be informed of each floating cranes data. And weighting factor is calculated by considering all hazards during the operation and the general operation manual is confirmed based on the factor. This paper introduces the procedure for lifting operations by parallel Connected Floating Cranes using synchronized operation system, and its applications to lifting operation of a heavy cargo such as barge lifting test, floating dock installation and 900 ton goliath crane replacement operation, etc.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.3
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• pp.563-572
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• 2001

A conventional motor in a crane has a taco generator to feed back the number of turns to a main controller. The taco generator is contacted to a motor shaft through the coupling. Errors in a crane have often occurred because the coupling has worn out while the motor is turning. In this paper, we design the device of the frequency to voltage transducer in a motor. The device is composed of a rotary encoder, a speed measurement using PIC16F84 controller, a display, and a direction-decision block. The rotation of a motor is recognized by the rotary encoder and microcontroller counts the number of turns of a motor. The emergency signal is generated if the frequency goes over or below the speed limit of a motor. And the device can acknowledge the rotation direction of the motor after 6。 rotation. The simulation results and the test for a implemented device have shown that the transducer of a frequency to a voltage can replace a taco generator in a crane.

• Journal of the Korea Society of Computer and Information
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• v.9 no.4 s.32
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• pp.117-125
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• 2004

The berth and crane scheduling problem in a container terminal encompasses the whole process of assigning berth to each ship. determining the duration of berthing, assigning container cranes to each ship, and determining the specific start and end time of each crane service, for all the ships scheduled to be arriving at the terminal during a certain scheduling horizon. This problem is basically a constraint satisfaction problem in which all the constraints should be satisfied. However, it is also an optimization problem because the requested arrival and departure time should be met for as many of the scheduled ships as possible. while the operation cost of the terminal should be minimized. In this paper. I present an effective approach to solving this problem, which combines both constraint satisfaction search and iterative improvement search. I test this method on a real world container terminal problem and the results show that the method can produce better results than any other existing method.

• International Journal of Aeronautical and Space Sciences
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• v.2 no.1
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• pp.103-109
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• 2001

Productivity enhancement program of wind tunnel testing has begun at Korea Aerospace Research Institute Low Speed Wind Tunnel (KARI LSWT). A previous test record of a canard airplane model was adopted to examine the current status of wind tunnel testing efficiency. The time consumed to perform testing activities from the model preparation to data collection was broken down and the results were compared with those of the recent Boeing low speed test result. The efforts to improve the wind tunnel productivity consisted of the installation of mini crane underneath of test section, fabricating lift device for image fairings, model configuration changing rigs and the modifications of external balance system. Time reductions for changing strut interface platform and installation of image fairings. These effects showed more than 70% improvement over the previous test time. Integration of the new and modified systems will improve productivity of wind tunnel testing in KARI LSWT.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.87-92
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• 2003

Generally, in jack up rig design for harsh environment, its leg height is a major factor for achieving a sufficient serviceability & operability in terms of the worst environment and the workable depth. Due to difficulties in constructing such a high-slender leg, inaccessibility of yard fabrication equipment, etc. the construction of Jack up rig fur harsh deep sea has not been common. Method using heavy crawler crane, fabrication tower or extension by the floating crane vessel is still conventional construction but, considering high cost fur mobilizing heavy lift vessel (HLV) or additional marine work for implementing preload / full height test at sea, the ground-base construction is much advantageous. Air skidding method (ASM hereafter) is ground-based construction methodology, newly developed due to such requests. ASM could also be extended to similar engineering fields. This paper presents the operating sequence, design parameters and procedure which were verified through successful operation at the end of May 2002.

• Journal of the Korean Society of Safety
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• v.29 no.5
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• pp.67-73
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• 2014

Construction equipment such as tower crane should be installed in a field without appropriate anchorage to cause a collapse of crane. The anchorage capacity can be varied with Anchor length, concrete strength, anchor diameter, hooked or non hooked these variables will be made and tested in the study. It is shown what anchorage capacity will be more effective case by case. Hooked and non-hooked rebar anchor concrete weight with dia 22mm rebar are shown with initial displacement at 170~220KN of hooked case and 200~210KN of non-hooked one which are linearly increased, without any ductility behavior with almost brittleness. Three(3) same test pieces are almost similarly behaviored without relation to hooked or non-hooked cases. It is found out that the bigger diameter of rebar becomes, the more resistant capacity could be made, but conversely ductility against sudden collapse similar to brittleness becomes the more insufficient. It is also found out that dia 16mm rebar could be more effectively applied to heavy support weight at construction sites.

• Journal of Ocean Engineering and Technology
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• v.22 no.4
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• pp.78-83
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• 2008

In recent years, small boats used for marine leisure have been steadily increasing because of the increase in national income and the desire for marine leisure. But the repair of such small boats in dry dock has pointed out many faults in small FRP-shipbuilding in terms if workspace and manpower. Lifting a boat from the water to land is done with a crane or by hand using a sling around the bottom of the boat. But dry dock work is limited by the scale of the boat, which corresponds to the crane capacity, with carelessness making it possible to capsize a boat and endanger life. The purpose of this study was the development of a marine docking system that would improve economical efficiency and safety, for which we carried out concept design, model tests, structural analysis, etc.