• Journal of radiological science and technology
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• v.42 no.6
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• pp.435-440
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• 2019

This is to study the accuracy of the actual size according to the TOD(table object distance; TOD) change when measuring blood vessels using angiography equipment, and to help the optimal selection of the device used accordingly. Balls similar to the size of common vessels were calibrated with TOD using 30 mm, 20 mm, 10 mm, 5 mm and acrylic phantoms, catheter calibration from 0 cm to 10 cm, 20 cm and 30 cm, respectively. It was measured whether there was a change in the measured value according to the change. The equipment used was GE Innova 3131 IQ equipment, and the image reconstruction method was GE AW4.7 post processing program. Two radiotechnologists were scanned three times by catheter calibration method and 3DRA(3dimension rotational angiography; 3DRA) volume rendering method. The independent sample T-test showed 0.981 (p> 0.05) to verify the significance between the two observers. As a result, in case of catheter calibration, the error rate at TOD 0 mm and 10 mm is within ± 10%, but when the TOD is changed to 20 mm and 50 mm respectively, the tolerance is ± 10% except for 30 mm ball exceeded. On the other hand, 3DRA was included within the tolerance range of ± 10% overall even when the TOD was changed from 0 mm to 50 mm. In the catheter calibration method, the larger the TOD, the larger the error range, and the 3DRA method was able to measure vascular vessels accurately close to the actual measurement without any consideration of the TOD.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.32 no.4
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• pp.363-371
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• 1996

The Steering and Sailing Rules of International Regulations for Preventing Collisions at Sea now in use direct the best aid - action to avoid collision by the stand - on vessel. But these rules do not refer to the safety relative distance between two vessels when she should take such action. In this paper, the author analyzed the ship's collision avoiding actions from the viewpoint of ship motions and worked out mathematical formulas to calculate the relative distances necessary for taking action to avoid collision. Figuring out the values of maneuvering indices through experiments of 11 actual ships of small, medium, large and mammoth size, the author applied these values to the calculating formulas and calculated the minimum relative distances. The main results are as follows: 1. It was confIrmed that the stand - on vessel should keep the greatest relative distance for taking best aid - action to avoid collision when the cross angle of course was $90^{\circ}$ and near it(70-$90^{\circ}$ ). 2. When the cross angle of course was $90^{\circ}$ , the minimum relative distance of small vessel(GT: 160-650tons) was found to be more than about 6.8 times of her own length, and those of medium(GT : 2,300-3,500tons), large(GT : 22,OOO-62,OOOtons) and mammoth(GT : 91,000-139,000tons) vessels were found to be more than about 9.0 times, about 5.4 times and about 6.8 times of their own lengths. 3. It was confIrmed that collision danger was greater when crossing angle was obtuse than in an acute angle, therefore greater relative distance was to be kept by the stand - on vessel for taking best aid - action to avoid collision in the case of the obtuse angle. 4. In every vessels, in the case of $90^{\circ}$ cross angle of course the safety minimum relative distance was found to be more than about 9.0 times of their own lengths.

• Journal of Ocean Engineering and Technology
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• v.30 no.2
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• pp.69-74
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• 2016

A new wave-piercing-type high-speed planing boat without a chine was developed, and its basic performance was investigated in a model test, including the resistance, trim, and sinkage. The maximum speed of the developed ship was 35 knots. The hull form was developed by combining a VSV (very slender vessel) and TH (transonic hull), which have large deadrise angles at the bow. The main dimensions were estimated by a statistical approach using actual ship data. The effect of a side fin attached at the stern near the water line was investigated from a resistance point of view. It was found that the developed hull form showed the possibility of a new concept for a high-speed planing hull without a chine, and the side fin played an important role in increasing the resistance performance by controlling the trim and sinkage in the high-speed range.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.583-591
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• 2005

The ship plating is generally subjected to combined in-plane load and lateral pressure loads. In-plane loads include axial load and edge shear, which are mainly induced by overall hull girder bending and torsion of the vessel. Lateral pressure is due to water pressure and cargo. These load components are not always applied simultaneously, but more than one can normally exist and interact. Hence, for more rational and safe design of ship structures, it is of crucial importance to bitter understand the interaction relationship of the buckling and ultimate strength for ship plating under combined loads. Actual ship plates are subjected to relatively small water pressure except for the impact load due to slamming and panting etc. The present paper describes an accurate and fast procedure for analyzing the elastic-plastic large deflection behavior up to the ultimate limit state of ship plates under combined loads. In this paper, the ultimate strength characteristics of plates under axial compressive loads and lateral pressure loads are investigated through ANSYS elastic-plastic large deflection finite element analysis with varying lateral pressure load level.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.5
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• pp.579-586
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• 2005

Recently, it has demanded to the wireless monitoring system in stand-alone PV power generation system. We propose the multiplex monitoring method using RF unit of low-price. RF unit consists of RF modem and communication controller. It is also able to use by repeater to communicate long distance. In this paper. two algorithms were programmed by CCS-C and C++ for multiplex monitoring method, The algorithm of choosing unit was used 'select and poll method' and the course assignment algorithm was embodied with 'Bellman-Ford algorithm'. The good result was achieved in the actual test without communication-data lose. The proposed method will be applied such as monitoring system of PV light on the wayside, monitoring system of unmanned lighthouse, monitoring system of refrigeration container on vessel and so on. It can be applied in the field that various ocean energy system.

• Journal of Environmental Science International
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• v.20 no.5
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• pp.599-610
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• 2011

Emission of air pollutants such as nitrogen oxides ($NO_x$), hydrocarbons (HC), $SO_2$, and particulate matter (PM) and $CO_2$ from ship during 2009 in Busan port was estimated based on activity-based method. The significant fraction (> 50%) of ship emission resulted from container and general cargo ships. Emission at port operation mode was the most dominant compared to at sea and maneuvering modes. Emission at North port was the largest source of air pollutants among ports. The magnitudes of air pollutants $NO_x$, $SO_2$, HC, $CO_2$, and PM in Busan port were $8.7{\times}10^3$, $8.23{\times}10^3$, $0.35{\times}10^3$, $4.86{\times}10^6$, and $0.67{\times}10^3$ ton/yr, respectively. The ratio of $NO_x$ to VOC is about 25. Our ship emission estimate is 2 times higher than that in CAPSS emission inventory.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.648-655
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• 2005

The resilient mounts of a diesel engine installed onboard a ship should be designed for both static and dynamic loads. If possible, the resonance frequencies of the six rigid body modes of the installation and the flexible modes of the engine support structure should not lie within the engine operation range. In this paper a design criterion is proposed to evaluate an isolation system which involves the summation of dynamic forces transmitted through the resilient mounts and elastic potential energy index stored in the mounts. A case study is also presented in which a diesel engine generator, which had an elastic foundation and was mounted in a 5500 TEU container vessel, was studied both theoretically and experimentally. The theoretical analysis of the test model was performed by using a single mass 6 degree of freedom system. Actual measurements of mechanical vibration of the Engine and its foundation onboard were carried out, which showed the importance of including the flexibility of the engine support structure in the mode

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.12
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• pp.815-821
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• 2015

Maritime safety has been more critical recently due to the occurrence of shipboard accidents involving prime movers. As such, the propulsion shafting design and construction plays a vital role in the safe operation of the vessel other than focusing on being cost-efficient. Smaller vessels propulsion shafting system normally install high speed four-stroke diesel engine with reduction gear for propulsion efficiency. Due to higher cylinder combustion pressures, flexible couplings are employed to reduce the increased vibratory torque. In this paper, an actual vibration measurement and theoretical analysis was carried out on a propulsion shafting with V18.3L engine installed on small car-ferry and revealed higher torsional vibration. Hence, a rubber-block type flexible coupling was installed to attenuate the transmitted vibratory torque. Considering the flexible coupling application factor, reduction gear stability due to torque variation was analyzed in accordance with IACS(International Association of Classification Societies) M56 and the results are presented herein.

• Nuclear Engineering and Technology
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• v.12 no.2
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• pp.127-134
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• 1980

Shielding problems associated with neutron streaming through the reactor vessel cavity of pressurized water reactors are discussed to a certain extent with the actual examples in the currently operating reactors. Various remedial techniques are proposed herein to mitigate the tedious neutron streaming phenomena including piling up in heaps of temporary boron-containing bags and the installation of permanent shield structure making use of a certain refractory materials. In conclusion, optimum cavity shielding design concepts are presented with special emphasis on such major factors as the identification of major neutron streaming path, selection of necessary shielding materials with acceptable constraints, detailed design characteristics and physical configuration as well as the formulation of dependable mathematical tools to predict the final outcome of each design concept proposed in the context.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.12
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• pp.208-213
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• 2010

This paper deal with an analysis of the ground surface potential profiles using a hemispherical scaled-model. Because it is very difficult to draw valid conclusions concerning a general grounding problem from actual field data, scale model tests can be used to determine the ground surface potential profile around the grounding electrodes according to the configuration of grounding electrodes. In this work, a hemispherical vessel with a diameter of 1,100 [mm] was employed to simulate uniform soil and CDEGS program was employed to compare the measured and simulated results. As a result, the ground surface potential around the grounding electrode was significantly raised and the ground surface potential at the just upper point of ground electrode particularly was higher than other points. The ground surface potential of counterpoise was higher than other grounding electrodes such as mesh and grounding rods and the ground surface potential strongly depends on the frequency responses of grounding electrodes. Also the results measured with the small-sized model were in reasonably agreement with the data obtained from simulation.