• Bulletin of the Society of Naval Architects of Korea
• /
• v.27 no.2
• /
• pp.63-77
• /
• 1990

The combined deckstructure-car system of a car carrier is especially sensitive to hull girder vibrations due to mechanical excitations and wave loads. For the free and forced vibration analysis of the system, the analytical methods based on the receptance method and two schemes for efficient applications of the methods are presented. The methods are especially relevant to dynamical reanalysis of the system subject to design modification or to dynamic optimization. The deck-car system is modelled as a combined system consisting of a stiffened plate representing deck, primary structure, and attached subsystems such as pillars, additional stiffeners and damped spring-mass systems representing cars/trucks. For response calculations of the system subjected to displacement excitations along the boundaries, the support displacement transfer ratio conceptually similar to the receptance is introduced. For the verification of accuracy and calculation efficiency of the proposed methods, numerical and experimental investigations are carried out.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.30 no.4
• /
• pp.324-331
• /
• 2024

The height of large car and truck carriers from the keel to the wheel house is 44 ~ 46 m, and as the car-carriers increases in size, it exhibits the 'top heavy' characteristic, where the upper section is heavier than the lower section. This study aims to estimate the maximum outward heel angle of the Golden Ray car-carrier (G-ship) during turning maneuvers for accident investigation and the prevention of similar accidents. The theoretically calculated maximum outward heel is 7.5° (at 19 kn, rudder angle 35°) with a GM of +3.0 m or higher, and 16.7° with a GM of +1.85 m. Meanwhile the experimentally modified maximum outward heel is 10.5° (at 19 kn, rudder angle 35°) with a GM of +3.0 m or higher, and 23.3° with a GM of +1.85 m. The G-ship is maneuvered during an accident at a speed of 13 kn, at starboard rudder angle of 10° to 20°, it changes course from 038°(T) to 105°(T) based on the instructions of the on-board pilot. At this time, the maximum outward heel is estimated to be between 7.8° and 10.9° at the port side, which is 2.2 times higher than the normal outward heel. In the IS code, cargo ships are required to exhibit a minimum GoM of +0.15 m or more. The maneuvered G-ship exhibits a GoM of +1.72 m. It is not maneuvered because it fails to satisfy the international GoM criteria and because its GoM is insufficient to counteract the heeling moment during the maneuver. This study is performed based on accident-investigation results from the Korea Maritime Safety Tribunal and the USCG.

• Tribology and Lubricants
• /
• v.12 no.3
• /
• pp.92-99
• /
• 1996

Energy-efficient contrarotating propeller systems have been recently reviewed as one of alternative means in marine car-carrier applications. Contrarotating rotors preclude the usage of conventional plain journal bearings due to the lack of load carrying capacity. A new multi-recess hydrostatic contrarotating journal beating test facility has been designed and installed to test the static load carrying capacity. Measurements of flow rates and orbits have been investigated by testings on a overhung-type contrarotating rotor system which is supported by a hydrostatic journal bearing. Numerical results of static equilibria were compared with test results. Various contrarotating speed combinations, and supply pressure conditions were selected. The numerical predictions of orbit centers and flow rates are generally accurate.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.6
• /
• pp.1164-1169
• /
• 2009

In this study, the bracket for car was designed in 3D using Cimatron Die Design, one of the automatic modules. To facilitate the stamping of the product, the layout of the strip was adjusted slightly. The blank layout of the double-width, 2-line, 2-pull out inner carrier was then optimized as a single arrangement. 3D design was completed in 11 processes.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2011.06a
• /
• pp.362-364
• /
• 2011

자동조타장치에 의한 조선을 행할 시, 선박의 정침성은 Autopilot의 P와 D값 설정에 따라 많은 영향을 받게 된다. 이 값들은 선종별로 외력에 따라 조정되어야 한다. 이 연구에서는 바람에 의해 가장 많이 영향을 받는 자동차운반선(Pure Car Carrier, PCC)을 대상으로 하여, 풍압력하에서 자동조타시 P와 D치의 적정 설정값을 알아 보았다. 이를 위하여 대상 선박을 저속항행하는 시뮬레이션을 실시하였고, 각 P-D 설정값에 따른 최대 횡이동거리, 횡이동시간 그리고 주어진 침로로 복귀하는데 걸린 시간을 비교하였다.

• Journal of Navigation and Port Research
• /
• v.32 no.4
• /
• pp.271-277
• /
• 2008

When performing steering by an autopilot (automatic steering gear), a sensitivity adjustment is mainly determined by P value and D value. These values differ in the optimal combination by model of ship and external forces. This research was carried out simulation case studies and examined movement of Pure Car Carrier, which easily received ship by wind pressure influence in low speed We investigated the relation of horizontal migration(transfer) of ship's body and P-D value. Based on it, four parameters of P-D at approaching berth could be suggested Hence there were suggestions of parameters; Distance to maximum lee point, Time to maximum lee point, Time to return to original course and Time to 300th second. The correlation of these parameters and P-D value were also considered. As a result, we think that this index, like formulated P-D, leads to an easy and safe navigation by utilizing these indices.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2019.11a
• /
• pp.185-186
• /
• 2019

카캐리어선에 화물을 선적하기 위해서는 각 화물의 선적 순서와 위치를 결정해야 하며, 이를 선적 계획이라 한다. 선적 계획은 선박의 무게 중심과 공간 손실률, 화물 재취급(re-handling) 횟수를 최소화하도록 수립된다. 최적의 선적 계획을 수립하기 위해서는 여러 후보 선적 계획들을 평가하여 적합도(fitness)가 가장 높은 것을 탐색하여야 한다. 하지만 화물 종류의 수와 도착지의 수가 증가할수록 후보 선적 계획의 수가 증가하게 되어, 탐색 시간과 계산 비용이 커지는 문제가 발생한다. 본 논문에서는 탐색 공간이 매우 큰 환경에서 최적의 선적 계획을 효율적으로 탐색하기 위해 유전 알고리즘(genetic algorithm)을 사용한다. 또한, 선박의 무게 중심과 공간 손실률, 화물 재취급 횟수로 목적 함수(objective function)를 구성하여 최적 선적 계획을 탐색한다. 실험 결과, 휴리스틱(heuristic) 방식보다 공간 손실률과 재취급 횟수가 향상되었으며, 특히 재취급 횟수는 70% 감소하였다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.11
• /
• pp.494-500
• /
• 2019

The purpose of this study was to determine a method to prevent damage during the transfer of loading through optimal design of loading transfer software for an ammunition-carrying armored vehicle. Typically, an ammunition carrier armored car is equipped with an automated charge transfer system. The load is intermittently damaged during the loading of the cargo, and this needs to be improved. The following improvements and verification tests were carried out. As impact speed increased, the loading speed was reduced 60%, and a special fixture utilizing a force gauge was developed and tested. If the maximum current of 11A for the servo controller is output when the load of the conveyor is generated by interference inside the loading tube, there is a possibility of charge breakage. If the maximum current is low, the load cannot be loaded. In the loading test for the ammunition carrier armored car with the actual charge, the improved design was found to be valid, as the load was not damaged and occurred nominally.

• Journal of Korea Port Economic Association
• /
• v.33 no.4
• /
• pp.73-82
• /
• 2017

Korea is the fifth largest producer of automobiles in the world, and this industry accounts for the highest portion of the entire manufacturing industry. It is an especially important industry occupying second place in the top 10 export items in Korea. Korea exports about 3 million units of cars produced in the country and abroad, based on new cars and excluding second hand cars. Japan, along with Korea, represents a high portion of the global automobile industry, and it exports more than 4 million cars to the rest of the world. In particular, both Korea and Japan export automobile and used cars produced within the country, almost all of them by PCC(Pure Car Carrier) or PCTC(Pure Car Truck Carrier). Therefore, automobile export ports are located near automobile factories, and are being used in export to foreign countries. However, there are inefficient problems, such as poor port facilities, yard space shortage for loading and unloading operations and lack of proficiency of cargo handling companies. As a result, there are delays in cargo operations, or ships waiting have occurred. Therefore, the purpose of this study is to measure and compare the efficiency of automobile export ports in Korea and Japan. To measure the efficiency of automobile export port, we used CRS and VRS models from DEA. The input and output parameters were set as length of quay, yard area and throughput of cars, and DMUs are 25 ports for evaluating the efficiency. As a result of the efficiency measurements, two Korean ports (Gwangyang and Ulsan) and three Japanes ports (Kanda, Omaezaki, Kanmon-Shimonoseki) showed high efficiency in both models. These results can be used to establish strategies for enhancing efficiency and competitiveness of automobile export ports in Korea and Japan.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.27 no.1
• /
• pp.35-44
• /
• 1990

Most of the medium-size ships are powered by large-bore, long-stroke, slow-speed and two-stroke diesel engines in order to improve the fuel efficiency. Such a propulsion plant develops low-frequency excitation forces/moments of significant magnitude. A RO/RO car/truck carrier is also one of the cases. In this paper, the rational methods for analysis of vertical and coupled horizontal-torsional vibrations are presented. Taking account of unusual characteristics of the hull form and structural systems, the emphasis is put on modelling methods based on beam analogy, calculation of system parameters such as added mass and its center, polar added-mass moment of inertia, shear coefficient of hull sections and coupling degree in antisymmetric modes, and modal analysis of forced vibrations.