• Journal of Ship and Ocean Technology
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• 제10권1호
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• pp.1-9
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• 2006

The resistance reduction by an air lubrication effect of a large air cavity covering the hull bottom surface and the similarity relations involved have been investigated with a series of towing tank tests of three geometrically similar models. The test results of geometrically similar models have indicated that a large air cavity was formed beneath the bottom having a backward-facing step by artificially supplying air is effective for resistance reduction. The areas of air cavity and the required flow rates of air are directly related to the effective wetted surface area. The traditional extrapolation methods seem to be applicable to the estimation of the resistance in the tested range if corrections are made to account the changes in the frictional resistance caused by the changes in the effective wetted surface area. To investigate the effectiveness of air lubrication in improving the resistance performance of a practical ship, a small test boat having a backward-facing step under its bottom has been manufactured and speed trials in a river have been performed. Air has been supplied artificially into the downstream region of the bottom step to form a large air cavity covering the bottom surface. The results have confirmed the practical applicability of air lubrication for the resistance reduction of a small high-speed boat.

• 동력기계공학회지
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• 제16권4호
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• pp.17-23
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• 2012

In this study, the numerical simulation and basin model test have been performed to evaluate sea worthiness and resistance performance for a small pre-planning three type of leisure boats which are U, V, Y shapes of hull forms. As a well known commercial CFD code, Maxsurf, was applied for modeling hull forms used as the solver of motion analysis. Also the model resistance test was carried out to estimate the effective power of boat in the basin tank. Numerical simulation and model test results show that Y-shaped hull is better than the other types in terms of heave and pitch motion, having a key effect on a boat sea worthiness. But V-type hull is more efficiency than others cases in resistance performance.

• 한국가시화정보학회지
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• 제13권1호
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• pp.9-14
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• 2015

There have been many attempts to reduce the cost of transportation. Especially, drag reduction of heavy vehicles has enormous influence on energy saving by reducing the driving power of the vehicles. In this study, the effects of drag-reducing additive devices such as side skirt, boat tail and cab-roof fairing on the drag reduction of a 5 ton truck model were experimentally investigated. The aerodynamic performance of these flow-control devices attached to heavy vehicle was evaluated through wind tunnel test. In addition, flow patterns around the truck model were visualized by using smoke tube method. The drag coefficient is reduced by up to 5.7%, 7.16% and 22.2% by the side skirt, boat tail and cab-roof fairing, respectively. The interactive effect of the side skirt and boat tail was also investigated.

• 해양환경안전학회지
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• 제21권6호
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• pp.784-789
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• 2015

본 연구는 소형 고속정의 운항한계를 검토하기 위하여 수행되었다. 일반적으로 내항성능의 검토는 선형의 결정 단계 전에 이루어지지만 본 연구는 선박의 건조가 완료된 후에 이루어졌다. 검토 결과, 종동요, 수직 및 수평가속도, 슬래밍의 운동성능은 특정한 조우각을 제외하고는 만족하였으나 갑판침수의 경우에는 해석을 수행한 모든 조건에서 만족하지 않았다. 이것은 대상선박의 크기가 소형이기 때문에 선박의 속도나 파도와의 조우각보다는 해상상태가 설정한 내항성능 기준의 만족 여부에 더 큰 영향을 미쳤기 때문으로 보인다.

• 대한조선학회논문집
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• 제44권6호
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• pp.635-646
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• 2007

Human Powered Vessel Festival (HPVF) hosted by the College of Engineering of Chungnam National University, the Society of Naval Architects of Korea and the Korea Ocean Research & Development Institute has been held annually in Daejon since 1999. Solar boat powered by solar energy appeared for the first time in 2006, and it is expected that more new teams will enter this competition in the coming years. In this paper it is described that design procedures and manufacture processes of the solar boat named EPISODE. Firstly, It is aimed to understand compositions of the electric system and their performance properties and to show the design procedures using commercial design packages line WAVIS, CATIA, HCAD etc. Through the trial test, we confirmed ship speed, maneuverability, durability and operation condition of the electric system and found some problems. We plans to make reported problems go away and install hydrofoils for more improved speed performance.

• 한국항만학회지
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• 제2권1호
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• pp.75-106
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• 1988

As port transport system consists of subsystems such as navigation system, cargo handling system, storage system, inland transport system, and Management and Information system, the productivity of this system is determined by the minimum level of subsystem. From the viewpoint of elaborating the efficiency of integrated system, it is valuable to determine the optimal level of harbour tug boat which is the most important factor of navigation system. This paper treats the optimal amount of harbour tug boat by simulation, and applied to Pusan port. In the course of simulation, an emperical formula is introduced for determining the Horse Power (HP) of tug boat by the ship's gross tonnage (G/T) refering to the cases of various ports of other countries, that is ; $Y=9.96X^{0.6}+569$. X : The gross tonnage of vessel (G/T). Y : The Horse Power (HP) of tug boat. The results of the simulation are summarized as follows ; 1) In 1987, three or four low-powered harbour tug boats, five mid-powered harbour tug boats and four high-powered harbour tug boats are necessary in the mean level. But, five or seven low-powered harbour tug boats, ten mid-powered harbour tug boats and eight high-powered harbour tug boats are necessary lest delay should occur at all. 2) In 1992, 1lee or four low-powered harbour tug boats, six mid-powered harbour tug boats and seven high-powered harbour tug boats are estimated and be necessary in the mean level.

• 한국농공학회논문집
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• 제52권6호
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• pp.9-17
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• 2010

In this paper, an automatic cruise system of unmanned boat was developed for surveying water depth in reservoir using GIS (geographic information system)-GPS (global positioning system) Technologies. the automatic cruise system consisted of an automatic path generation program (APGP) and an automatic boat control program (ABCP). A grid processing method with $3{\times}3$ roving window in GIS function was used to develop the APGP. For development of the ABCP, GPS and its coordinate calculation technique were introduced. The developed system was tested to verify the applicability for a sample reservoir, Misan reservoir located on Ansan city of Kyunggi province. From the test results, this study found the APGP generated cruise path automatically according to input condition on grid size of 5 m, 10 m, and 20 m, as well as, the ABCP also tracked well the cruise paths with high position accuracy. Another verification result on surveying time for 20 ha of water area also showed that the new system could survey water depth of reservoir quickly, including very high quality of spatial resolution.

• 한국기후변화학회지
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• 제7권2호
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• pp.177-184
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• 2016

Recently, the need for technology development of commercial vehicle fuel consumption has emerged. Fuel economy improvement of transport equipment and transportation efficiency, and increasing attention to the logistics cost reduction measures. Increasing attention to the logistics cost reduction measures by fuel economy improvement of transport equipment and transportation efficiency. In this study, we have installed aerodynamic reduction device (side skirt, boat tail) to 14.5 ton cargo trucks and 45 ft tractor-trailers. And the fuel consumption was compared installed before and after. Fuel economy assessment for the aerodynamic reduction value device was tested by modifying the SAE J1321 Joint TMC/SAE Fuel Consumption Test Procedure - Type II test in according domestic situation. Greenhouse gas reductions were calculated in accordance with the scenario, including fuel consumption test results. When the 14.5 ton cargo trucks has been equipped with side skirts and boat tail, it confirmed the improvement in fuel efficiency of 4.72%. One Heavy-duty truck's the annual greenhouse gas reductions value are $6.86ton\;CO_2\;eq$. And if applying the technology to more than 50% of registered 15 ton trucks, greenhouse gas reductions are calculated as $686,826ton\;CO_2\;eq./yr$.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2019년도 춘계학술대회
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• pp.98-100
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• 2019

In the past, there were several researchers investigating waves generated by a small boat. Wave generated by a ship can be divided into two distinct systems of waves, such as transverse and diverging waves. It is necessary to understand the behavior of a ship in waves generated by a small boat near port in the view point of ship safety. In this study, the motion of moored floater in waves generated by a small boat near port is investigated. The model test is performed in waves in a square tank in Changwon National University (CWNU). IMU and optical-based system which uses the technique of recording and capturing attitude with respect time are used for measuring 6DOF motion of the moored floater. In addition, tension gauges are used to measure the tension of mooring lines. The effect of waves generated by a small boat on motion of the moored floater near port is investigated through performing the model test in various wave directions of virtually but reasonably assumed wave scenarios.

• 대한원격탐사학회지
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• 제37권1호
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• pp.69-84
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• 2021

Awareness of boats is a main issue in areas of fishery management, illegal fishing, and maritime traffic, etc. For the awareness, Automatic Identification System (AIS) and Vessel-Pass System (V-PASS) have been widely used to collect the boat-related information. However, only using these systems makes it difficult to collect the accurate information. Recently, satellite-based data has been increasingly used as a cooperative system. In 2015, U.S. National Oceanic and Atmospheric Administration (NOAA) developed a boat detection algorithm using Visible Infrared Imaging Radiometer Suite (VIIRS) Day & Night Band (DNB) data. Although the detections have been widely utilized in many publications, it is difficult to estimate the night-time fishing boats immediately. Particularly, it is difficult to estimate the threshold due to the lunar irradiation effect. This effect must be corrected to apply a single specific threshold. In this study, the moon phase was considered as the main frequency of this effect. Considering the moon phase, relational expressions are derived and then used as offsets for relative correction. After the correction, it shows a significant reduction in the standard deviation of the threshold compared to the threshold of NOAA. Through the correction, this study can set a constant threshold every day without determination of different thresholds. In conclusion, this study can achieve the detection applying the single specific threshold regardless of the moon phase.