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Recently, ship owners have been requiring the assessment of the maneuverability of a twin-screw ship under machinery failures. In this paper, we are only focused on the propulsion failure among propulsion failure, power supply failure, steering system failure etc. First of all, the mathematical model for the twin-screw 174K LNGC is verified by comparing the simulated results for 35˚ turning test, 10˚/10˚ zigzag test and 20˚/20˚ zigzag test under normal operating condition and those obtained from free running model tests. And, sea trial results of 216K LNGC under single propeller failure are compared with those of 174K LNGC under identical condition to verify the proposed method to predict maneuverability under single propeller failure. After the straight line maneuver is simulated under the single propeller failure, the speed and equilibrated heading and rudder deflection angles at steady state are predicted. After the IMO maneuvering tests are simulated under the single propeller failure, the results are reviewed to investigate the maneuvering characteristics due to the failure.
Recently, ship owners are requiring an assessment of sailing safety of a ship from an analysis considering maneuverability and environmental loads etc. In this paper, we propose a new approach to assess sailing safety by considering the prescribed parameters. The concept of sailing safety is developed from DP capability analysis and is based on the maneuvering simulations. While the ship is continuously disturbed due to irregular environmental loads during the simulations, it is steered to keep its course along the way points assumed along a straight path. After relative distances between four edges of the ship and allowable safety boundaries are calculated for 3 hours, the minimum values are obtained. The minimum distances are marked on a polar chart and we call this a quantified safe operation judgment chart which indicates quantified sailing safety.
Recently, ship owners have been requiring the assessment of the maneuverability of twin-screw ships under mechanical failures. Because this kind of assessment has not yet been conducted, it is necessary to study the types of machinery failures that can significantly affect the maneuverability of a ship, and to construct a procedure to simulate the maneuvering behavior under such failures. In this paper, the sole focus is the steering system failure from among the variety of failure types, and the maneuvering behavior of the ship under the single rudder failure is simulated for an investigation of the unique characteristics. First, the mathematical model for the twin-screw container ship is verified by comparing the simulated results for the 35˚ turning test, 10 ˚/10˚ zigzag test, and 20˚/20˚ zigzag test under the normal operating condition with those obtained from free running model tests. After the IMO maneuvering tests are additionally simulated under the single rudder failure, the results are reviewed to investigate the maneuvering characteristics that are due to the failure. Further, the 35°/35° zigzag test and the 35° turning test are simulated to additionally investigate the effects of the single rudder failure on the steering and turning abilities.
Ship owners had pursued higher benefits by demanding the new design and construction of ships with higher operational efficiency. There was a necessity for shipyards to suggest a more economical design and advanced operation concept in order to meet the demands. Especially, since BOG combustion and activation of the re-liquefaction unit had to be taken into account in ship design in addition to fuel oil and gas consumption, the evaluation of the operating efficiency considering the technological trends was necessary. In this paper, it was aimed to study the design philosophy and operation strategy by considering the effect of fuel oil and gas consumption, BOG combustion, and activation of the re-liquefaction unit on the operating cost for laden voyage according to ship speed, BOR, and activation of the re-liquefaction unit. For this purpose, the costs were acquired by conducting the sailing simulation of an LNGC based on a mathematical model including the maneuvering equations of motion. The design philosophy and operation strategy was reviewed in terms of the operating cost.
In order to predict the sailing performance of a LNGC during actual operation, it is necessary to consider not only the information about resistance, maneuverability etc. but also the information such as sea route and sailing scenario etc., comprehensively. In this paper, we propose a new approach to conduct the sailing simulation of a LNGC without full scale measurement data. Latitude, longitude, sea route, speed over ground, time in UTC obtained from AIS data are substituted for the measured data. By combining the model test results, design information, and AIS data, prediction of sailing performance is conducted from the coast of southern Taiwan to the coast of Madagascar. The simulation is verified by comparing the calculated time histories of RPM and power with those of measured RPM and power.
It was important to estimate the full-scale operating performance including actual RPM and engine power of a ship since the operation efficiency during a voyage could be evaluated from the values. In the previous research, an entire voyage was simulated by following recorded speeds obtained from AIS and full-scale measurement data. Although reasonable tendencies were observed in the estimated speed, actual RPM, and engine power, it was impossible for them to be completely corresponded with the measured values due to the difference between actual operation and mathematical model. In this paper, alternative approaches to cope with the speed, actual RPM, and engine power were suggested by following the given speed, RPM, and power respectively. After entire voyages were simulated according to a given value, the effects of the value on the estimated performance were investigated. And, it was confirmed that the appropriate approach could be differently chosen according to the aim of the simulation or given value.
Since IMO has discussed the effectuation of the EEDI, EEOI and SEEMP, each country, shipping company, shipbuilding company and research institute have been requested to prepare the design, construction and operation of the efficient ship. From the shipbuilding company's point of view, it was necessary to develop a method based on the maneuvering equations of motion in a bid to estimate the EEOI considering the design, model test results and the calculation results of the ship. In this paper, the estimation method of RPM, power and fuel consumption proposed in the previous research was developed to construct a framework that helps in the estimation of the EEOI. It was possible to estimate the EEOI from the estimated ship speed (distance), LNG cargo mass, fuel consumptions and emission factors according to the type of fuel. The rapid increase of the evaluated EEOI was observed when the LNGC with ME-GI engine executing the course changed with a large difference. This prompted the comparison of the type of fuel on the estimated EEOI by considering HFO, LNG fuel and MGO properties.
A mirrorless vehicle replaces a rear-view mirror and side-view mirrors with camera monitoring system to show video footage of the car's surroundings. These systems mostly replace a rear-view mirror with displays that show panoramic video. Geometric alignment-based image stitching is generally used to provide a real-time panoramic video, but its outcomes are vulnerable to unstructured camera arrays. In this paper, we propose a variable seam-line detection method for panoramic video with relatively high accuracy. Efficient cost computation to minimize stitch error for seam-line adjustments is presented. Our experiments generated panoramic images that turned out to be both viewer-friendly and realistic.
본 논문은 수중 추진기관으로 소형 액체로켓연소기를 적용하고 이를 시험 평가할 이동형 시험 장치를 설계, 제작하여 가압식으로 추진제를 공급하는 장치를 검증하기 위해 모사유체인 물을 사용하여 수류실험을 통해 안정적으로 작동하는 것을 확인하였다. 향후 설비 보완을 통하여 성능을 향상 시키고, 소형 제품의 다양한 시험 장치로 적용 할 것이다. This study aspire to apply small-sized LPRE(Liquid-Propellant Rocket Engine) as Underwater Thrust System, and to design and develop PTE(Portable Test Equipment) so as to examine the thrust system. PTE aims at supplying the propellant to the system with pressurization. In order to verify the performance of PTE, Spilling test was implemented with water whose characteristic is similar to taht of propellant in LPRE. The result from the test showed that the PTE follows designed requirements with stable performance. This research can be a potential source to further Test Equipment both for the improvement of performance and the application to diverse small-sized test devices.
본 연구에서는 하이브리드 추진기관의 수중시스템 적용을 위하여 Lab-scale 엔진을 이용한 수중연소시험을 수행하였으며 파열판 조기 파열 시 발생되는 초기 연소실 압력 상승에 관한 연구를 수행하였다. 하이브리드 수중추진기관의 초기점화 단계에서 점화제에 의한 파열판 조기 파열 현상에 따른 점화특성을 중점적으로 파악하였으며 착화 전 점화제에 의한 파열판의 파열은 수중추진기관 운용 조건에 큰 영향을 미치지 않는 조건을 파악하였다. In this study, underwater combustion test was performed to analyze the ignition characteristics of a hybrid underwater propulsion system in the presence of a rupture disc. LN2O and HDPE were used as oxidizer and solid fuel respectively, while the KNSB propellant was used as the ignition source. As a results, it was found that the burst of the rupture disc by the ignition source, prior to the main combustion, had a minor effect on the operability of the underwater propulsion system.