• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.7
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• pp.923-929
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• 2018

In this study, we analyzed the resistance performance and running attitude of a catamaran by numerical analysis with a conventional bow, which is generally applied, and a reverse, protruding bow. The shape of the reverse bow was compared through numerical analysis and model tests. The reverse bow shape showed an improved wave pattern by shifting the generation position of the forward divergent wave to the aft in comparison with a conventional bow shape. This effect was found to be effective in determining resistance and stable running attitude. The hull resistance improved by about 2.95 %. The comparative numerical analysis and model test for the reverse bow shape completed in this study should be useful for future hull design application.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.560-565
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• 2016

최근 대형 컨테이너선의 개발이 지속적으로 이루어짐에 따라 슬래밍에 의한 선수 및 선미의 구조안정성 문제가 대두되고 있지만 설계 단계에서 슬래밍에 대해 고려하기에는 현상의 복잡성으로 인해 어려움이 많았다. 이를 위해 KRISO에서 시행된 WILS JIP의 선수 단면 형상 및 선미 단면인 쐐기 형상으로 격자를 생성하여 EDISON CFD 다상유동 해석자를 통해 수치해석을 시도하였다. 기존 방식과 달리 계산 시간 절감을 위하여 격자 변형 기법을 적용하지 않고 모형 시험결과를 기반으로 한 유입류 조건을 설정하여 입수 충격 문제를 해석해보았다. 그 결과, 선미 형상의 경우 선행연구와 유사하게 실험 결과에 근접한 유체 충격력을 정량적으로 얻어낼 수 있었다. 선수 형상의 경우에서는 구상 선수로 인해 파생되는 센서 위치별 충격력의 변화를 확인할 수 있었으며, 실제 유동에 가까운 유동 형상과 슬래밍에 의한 충격력을 개략적으로 구할 수 있었다.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.4
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• pp.11-18
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• 2000

This paper is concerned with the generation of an optimal forward hull form by a nonlinear programming method. A Rankine source panel method based on the inviscid and potential flow approximation is employed to calculate the wave-making resistance and SQP method is also used for the optimization. The hull form is represented by a spline function. The forward hull form of a minimum wave resistance with the given design constraints is generated. In addition, the forward hull form of a minimum total resistance by considering the frictional resistance together with an empirical form factor is produced and compared with the former result.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.1
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• pp.50-62
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• 1994

This paper presents the results of a comparative analysis of the model test results to investigate the effect of bulbous bow installed on a large full form ship to the ship resistance performance. Seven parameters related to the shape of bulbous bow were selected and varied systematically to inquire their effects experimentally. A total number of twenty-three ship models with different bulbous bow were manufactured, and resistance tests. flow visualization test, and wave profile measurement were carried out for each model. For the comparative analysis between the various bulb forms and their model test results, bulbous bow forms are classified into nine groups according to their form characteristics. From the analysis of the trend of the resistance components, it was verified that form resistance has dominant effect on the total resistance of a slow full form ship. The model test and its statistical analysis showed that the direction of streamlines around bulbous bow has close relationship with resistance components. especially with form resistance

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.5
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• pp.601-608
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• 2019

In this study, the effect of hull appendages on the high-speed catamarans with reverse bow shapes is compared and analyzed by numerical analysis and circulating water tank model test. The reverse bow shape showed an improved wave shape by shifting the generation position of forward divergent wave to the stern direction and was effective in resistance and stable running posture (Kim et al., 2019). In the model test results of the running performance as the wave patterns and the change of the running posture due to the fin fitted with the inner side of the inverted bow and the interceptor, 1) Trim characteristics of the inverted bow 2) Improvement of superposition of inner wave by Fin 3) The trim control by the fin and the interceptor is considered to be effective in reducing the impact of the two hull connection decks (wetdeck).

• Proceedings of the KAIS Fall Conference
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• 2012.05b
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• pp.748-752
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• 2012

본 논문에서는 선체의 선수(船首)의 형상에 따른 유체의 유동에 관하여 연구 하였다. 선수(船首) 부분에 유체유동을 알아보고 압력과 속도를 비교하여 보다 나은 설계를 분석 하였다. 두 가지 형상설계를 기본 바탕으로 하였으며, 두 가지 형상에 세 가지 속도를 비교해 보았다. 설계된 선체 중 해석을 한 부분은 침수면을 해석 하였으며, 침수면 제외한 부분은 유동장 해석에서 생략하였다. 속도와 선체의 형상을 비교함으로써 더 효율적인 설계형상을 도출해 낼 수 있다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.7
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• pp.800-806
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• 2016

The maneuverability of a tugboat is affected by the slewing motion of a barge while the tug is navigating with the barge in water. Therefore, it is necessary to reduce the slewing motion of the barge to allow for safe towing work. In this study, a water tank experiment was performed to examine the factors affecting the slewing motion of a barge and improve course stability. The characteristics of slewing motion vary according to bow shape. Three barge models, each with a different bow shape, were selected as experimental subjects. A comprehensive analysis was performed to study the effects of various factors on the slewing motion of a barge such as the presence of a skeg and bridle, towing speed, and the length of the towline. The effect of the location of the skeg varied according to bow-hull form. The slewing motion of the barge decreased as the length of the towline increased, and this decrease was even greater when a bridle was connected to the towline. In addition, the slewing motion decreased significantly as the length of the bridle increased. The slewing angles did not show significant change with respect to towing speed.

• Journal of Ocean Engineering and Technology
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• v.26 no.4
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• pp.15-22
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• 2012

In this research, the relationship between the bow shape and green water phenomenon on the bow deck of an FPSO was studied using an experimental method. A 140,000 DWT FPSO was used as the objective hull form in the present research. The incident waves were regular types. The heights were 1.0 and 1.5 times the freeboard, and the length was equal in size to LBP. The wave heights and pressures on the deck were measured in experiments. Model tests were performed to determine the effects of bow flare angles, bow shapes, and a forecastle deck. The free heave and pitch conditions were applied to the models in these experiments. From the results of the model tests, an optimized bow shape was designed, which was found to decrease the green water impact loading. The results of this research could be used as fundamental data in the design of a bow shape.

• Journal of the Society of Naval Architects of Korea
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• v.28 no.2
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• pp.28-39
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• 1991

A study on the optimization problems to find forebode shapes with minimum wavemaking and frictional resistance was performed. The afterbody was fixed as a given hull and only forebode offsets were treated as design variables. Design variables were divided into the offsets of given hull and small variation from them. For the wavemaking resistance calculation, Neumann-Kelvin theory was applied to the given hull and thin ship theory was applied to the small variation. ITTC 1957 model-ship correlation line was used for the calculation of frictional resistance. Hull surface was represented mathmatically using shape function. As object function, such as wavemaking and frictional rersistance, was quadratic form of offsets and constraints linear, quadratic programing problem could be constructed. The complementary pivot method was used to find the soulution of the quadratic programing problem. Calculations were perfomed for the Series 60 $C_{B}$=0.6. at Fn=0.289. A realistic hull form could be obtained by using proper constraints. From the results of calculation for the Series 60 $C_{B}$=0.6, it was concluded that present method gave optimal shape of bulbous bow showing a slight improvement in the wave resistance performance at design speed Fn=0.289 compared with the results from the ship theory only.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.27 no.1
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• pp.75-82
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• 1991

The present paper describes a preliminary design method by using the computer graphics for creation of the fore and after body profiles of fishing vessel. It is well known that the Form Parameter design method has some merits at an early stage of design, and the B-spline curve generation technique has some prior properties in representing hull form with the computer graphic. The B-spline curve generation technique combined with the form parameter design method is employed to generate the profiles of fishing vessel. For fore body the stem profiles with bulbous bulb or without one are considered. And for after body the stern profiles of cruiser type and the transom type are generated with stern bulb or with shoe piece. Several examples will shown.