Jin-Won Yu

Resistance Performance of Korean Small Coastal Fishing Boat in Low-Speed Range

AbstractKorean small coastal fishing boats have the different kind of fisheries and customs against Japanese fishing boats. Those bring some influences on the principal parameters of hull form. In same displacement, Korean small coastal fishing boat has generally shorter length, draft and wider breadth than Japanese fishing boat. Fur thermore, even though the parameters of each hull form are similar, it is known that the resistance performance of Korean small coastal fishing boat is worse than that of Japanese fishing boat. In this study, the representative hull forms of Korean and Japanese small coastal fishing boats are selected and compared to evaluate the resistance performance of Korean fishing boat in low-speed range. The hull form of the Korean fishing boat is modified as comparison with that of the Japanese fishing boat to confirm the partial characteristic differences between the hull forms and the resistance performances. The representat ive partial characteristics of hull form are the gradient of chine line, keel shape and stern length. The resistance performances of the modified hull forms are evaluated by INHAWA VE which is one of CFD program and model tests in towing tank. The results of the present study will be used to

A Study on the Resistance Performance of the Goose Neck Bulbous Bow by Numerical Simulation Method

Bulbous bow is one of the important design factors on the design of fore-body hull form. Using the interference technique of ship waves, the bulbous bow can decrease the wave resistance of ship. Recently, the goose neck bulb is applied mainly for high speed vessels like passenger ships and ferries etc.. Also, the goose neck bulb is applied for relatively high speed merchant vessels like container ships and LNG carriers. However, existing research papers about the goose neck bulb are not enough as reference data for the design of bow hull form. In this study, numerical calculations are carried out to investigate the bow wave characteristics of a high speed ferry with a normal high nose bulb or a goose neck bulb. By comparing the pressure distributions on the hull surface and the wave systems near the bow, the features of wave resistance reduction are discussed. Also, Numerical calculations were carried out for a series of goose neck bulbs to figure out the optimum bulb size. The maximum reduction rate of pressure resistance for the fore-body is achievable up to 8% by adopting the goose neck bulb in the present calculation.

A Study on the Effective Horsepower Estimation for Domestic Coastal Fishing Vessels

As the hull form of Korean fishing vessels is different from that of Japanese fishing vessels, the statistical regression analysis results of the resistance estimation for the Japanese fishing vessels is not able to be employed for the Korean fishing vessels just as it is. In this paper, it is introduced to an effective horsepower estimation method for the Korean domestic coastal fishing vessels, which is based on the statistical regression analysis of the model test results of the Japanese fishing vessels and the adjustment of those regression factors using the hull form data and model test results of Korean fishing vessels. The estimation results of the effective horsepower using the present prediction method are compared with experimental data. The comparison results show good agreements in the conventional speed range of fishing vessels.

A Study on the Resistance Performance of Korean High-Speed Small Coastal Fishing Boat

2,† ·Ae-Seon Park 1 ·Yoon-Jin Ha 1 ·Cheong-Kyu Park Abstract The study on the improvement of resistance performance is very important for coastal fishing boats in Korea, because the prices of fuel oil are gradually risen and the demand of high-speed fishing boats is increased lately. This study is concerned with the improvement of the resistance performance for Korean high-speed small coastal fishing boats. A semi-planing hull form of Korean small coastal fishing boat is selected in the role of initial hull. From the modification of the hull form parameters and the local characteristics of the hull form, the improvement of the resistance performance is achieved. The resistance performances of the initial and the modified hull forms are estimated by using a numerical simulation method. Also, ship model tests are carried out in ship model basin.

A Study on the Improvement of Resistance Performance for G/T 4.99ton Class Korean Coastal Fishing Boats

Korean fishing boats have had appropriate hull forms for the safety, stability and convenience of fishing ability. However, Korean fishermen are recently concerned about the resistance performance and speed of Korean fishing boats, because the prices of fuel oil are gradually risen, also the exhausting of fish resources and the demand of high speed fishing boats are increased. Therefore, the necessity of the study on the improvement of resistance performance for Korean small coastal fishing boats is gradually increased. This study compares the hull form characteristics of Korean fishing boats with those of Japanese fishing boats, and the hull form of a representative Korean fishing boat is modified. From the modification of the hull form parameters for the Korean fishing boat, the improvement of resistance performances is evaluated. Moreover, the increase of resistance performances is also achieved from the modification of local characteristics for the hull form of the Korean fishing boat. A computational method and ship model tests in towing tank are used for the conformations of the improvement of resistance performance.

A Study on the Bow Wave Characteristics for the Resistance-Minimized Hull Form of Small Fishing Boat

AbstractThis paper presents the analysis of resistance performance and bow waves for the resistance-minimized hull form of small fishing boat by using n umerical simulations and model tests. The resistance-minimized hull form is developed from an original hull form which is selected from existing small fisher boats in our count ry. In order to estimate the resistance performance for the original and the developed hull form, several numerical simulations and model tests are carried out. Marker and Cell(MA C) method and Marker-Density method are adopted to simulate the free-surface bow waves around advancing hull surface. The results of numerical simulations ar e compared with the model tests in towing tank. The results show that the resistance perf ormance of the resistance-minimized hull form is improved than that of the original hull form. The results of this study will be a good guide to the hull form development of small fishing boats in future. ※ Keywords: Fishing boat(어선), resistance-minimized(저항최소화), Performance estimation(성능추정), Bow wave(선수파), Model test(모형실험), Numerical simulation(수치계산)

A Study on the Bow Hull Form Design of Full Ship Considering the Nonlinear Waves

2 Abstract This paper introduces a new hull form design method for the bow of a full ship, by actively applying the relation between the fore-body hull form and its wave resistance characteristics. For the hull form design, the Series 60(CB=0.8) hull is chosen as the parent ship, and Krachts charts are used to determine the parameters of the bulbous bow in the early stages of hull form design. Several hull forms have been tested in order to obtain enough hull form variations with various bow shapes and design parameters in the search of the best design. In order to investigate the resistance characteristics of the designed hull forms, numerical simulations with corresponding model tests have been rigorously performed. For the numerical simulations, the Marker-density method is employed to track the nonlinear phenomena of the free surface(program IUBW). Model tests have also been performed to achieve an improved research performance using the designed hulls. Both numerical and experimental results show that the wave resistance of the hull forms can be effectively diminished if the bows are designed using the method introduced in this research. It is also expected that this research can facilitate better productivity in hull form design, especially at the preliminary design stage of a full ship type vessel.

Added Resistance and Seakeeping Ability of a Medium-sized Passenger Ship with Gooseneck Bulb

유가의 상승에 의한 연료비 증가는 중소 여객선사의 재무 상황 을 악화시키는 원인 중의 하나로, 이를 개선하기 위하여 저항성능 에 우수한 경제적인 선형의 확보가 필요하다. 여객선의 경우 일반 적으로 어느 정도 높은 운항속도를 가지기 때문에 저항성능 개선 을 위한 선형설계에 있어 조파저항감소를 위한 선수선형설계가 필 요하다. 선수형상의 중요한 설계개념 중 하나인 선수 벌브의 경우, 선수 벌브와 선수 어깨에서 발생되는 파도들의 상쇄에 의한 조파 저항감소를 얻을 수 있다. 유럽을 중심으로 여객선에 대하여 진행 된 연구 결과들을 보면, 여객선에 거위목 벌브(gooseneck bulb)를 적용함으로 저항성능 개선을 통한 연료비의 감소가 가능함을 보여 주었다 (Heimann & Harries 2003; Maisonneuve, et al., 2003; Valdenazzi, et al., 2003; Heimann 2005; James, 2006; Dominic, 2007). 거위목 벌브의 개념은 조파저항감소를 위하여 일 반 벌브들과는 다르게 수선면 위로 벌브의 체적 중심을 올리고, 벌 브 체적 중심 뒤에서는 벌브의 폭이나 높이를 일반 벌브들에 비하 여 작게 하여 좀 더 유리한 파도상쇄효과를 얻기 위함이다. 따라서 이러한 거위목 벌브를 여객선에 적용하기 위한 연구들이 진행되었 다. Yu, et al. (2010)의 연구에서는 유럽에서 연구되어진 여객선 선형 (Heimann, 2005)를 대상으로 거위목 벌브의 최대 폭을 변화 시켜가며 자유수면 변화와 압력저항 변화를 확인하였다. 그 결과 벌브 폭이 감소할수록 발산파는 증가하였지만 비선형파가 감소하 여, 압력저항이 감소됨을 확인하였다. Yu, et al. (2014)의 연구에 서는 거위목 벌브의 최대 폭, 횡단면 형상 그리고 높이방향 중심위 치와 길이들을 변화시켜가며 연구를 수행하여, 거위목 벌브 설계 에 활용 가능한 벌브 선형요소들의 상관관계를 파악하고자 하였다. 이러한 기존 국내외 연구들은 정수 중에서 평가된 저항성능에 대한 연구결과들이다. 하지만 실제로 선박의 운항 시 파랑에 의 한 부가저항이 발생되는데, 부가저항은 선박에 따라 정수 중의 저항보다 15~30%가량 증가할 수 있다 (Seo, et al., 2013). 따 라서 정수 중에서의 저항성능 뿐 아니라 파랑 중에서의 부가저항 성능을 파악하는 것 또한 필요하다. pISSN:1225-1143, Vol. 52, No. 4, pp. 290-297, August 2015

Improvement of the Resistance Performance for a G/T 29ton Class Coastal Angling Fishing Boat based on Hull-form Design

In this study, numerical simulations and model tests are performed for the hull-form development of a G/T 29ton class coastal angling fishing boat. The numerical simulations are mainly used for the design of bow hull-form and the resistance performance is improved by the adoption of high bulbous bow. And, the resistance performances of the existing boat and the designed boat are verified by the model tests. The results of the experiments and calculations show that the effective power of the designed boat is 13.6% less than that of the existing boat at design speed. Therefore, the results of this research could be used as one of the fundamental data for the design of G/T 29ton class coastal angling fishing boat.

A Study on the Resistance Reduction of G/T 190ton Class Main Vessel in Korean Large Purse Seiner Fishing System

In this study, hull form of main vessel of Korean large purse seiner fishing industry is developed for the improvement of resistance performance as well as for the satisfaction to the Standard of Fishing Convention, ILO. Through the modification of reference hull form parameters and local characteristics, the hull form development is carried out. The optimum hull form parameters are searched by Sequential Quadratic Programing(SQP) method with the power estimation method of Holtrop & Mannen. To minimize the wave resistance, bulbous bow parameters are determined by the bulbous bow design method of Alvarino. The plasmatic curve is redesigned from that of the reference hull by using Lackenby method. The resistance performances of the reference and designed hull forms are estimated by using numerical simulation method. Also, the judgment of seakeeping ability and the estimation of intact stability for the designed hull form is carried out. As a result, the optimum hull form is proposed. To verify the improvement of resistance performance, model tests are carried out in towing tank. The results show that the resistance of the designed hull form is about 14% smaller than that of the reference hull from at design speed. A new hull form proposed in this study can contribute to the development of the main vessel hull form of Korean large purse seiner fishing system.