• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.6
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• pp.597-603
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• 2012

It is necessary to accurately evaluate the resistance performance and estimate the towing power of a tugboat for safety towing operation at actual seas. In this study, we have carried out the model tests firstly to investigate the resistance performance and flow characteristics around the tugboat in still water. The experiments are performed in infinite depth in circulation tank using 1/33.75 scaled model from 5kts to 10kts(designed speed 7kts) considering the effect of adverse and favorable current. Then the numerical calculations are executed to analyze the response amplitude operator and added resistance on tugboat due to the waves. The results obtained by the present computation are compared with the those acquired from the experiments in still water. As a result, it is noted that the added resistance become larger at head sea and higher speed conditions. We can also observe that the EHP increase 70 percent in comparison with those in still water.

• Journal of Navigation and Port Research
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• v.34 no.10
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• pp.741-746
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• 2010

It is necessary to estimate more accurately the resistance of barge in still water and waves to compute the break load of towline and towing power for safety towing performance. The method proposed by government has calculated the total resistance of barge which is composed of frictional resistance, wave making resistance and air resistance considering the shape of hull and towing speed. However, the added resistance is equally applied with the significant wave height regardless of the type of vessels. In this study, we have carried out the numerical calculation to estimate the added resistance of wigley model in waves and compared with the experiment data to confirm the accuracy of the method. Then the computation was executed for the barge varying shape of the bow. As a result, added resistance of barge was differently occurred i.e. 0.3∼1.1 ton according to encounter angle, 0.4∼1.2 ton according to towing speed and 0.5∼1.1 ton according to shape of bow.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2010.04a
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• pp.345-346
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• 2010

본 연구에서는 모형실험 및 수치계산에 의해 정수중 부선 주위의 유통해석을 실시하였으며, 이를 통하여 객관적이고 정량적으로 부선의 저항추진 성능을 파악할 수 있었다. 먼저 희류수조에서 모형실험을 실시한 후, 실험에서 얻어진 데이터와의 비교를 통한 CFD의 유효성을 검증하고, 다른 형태의 예부선 선박 주위의 유동장 계산에 적용시켜 해결할 수 있는 가능성을 확인 하였다. 부선의 선수 형상에 의하여 저속일 때 25% 정도의 저항이 차이나는 현상을 모형실험을 통하여 파악할 수 있었으며, 유효마력은 7kts부터 급격히 증가하므로 적재상태별 경제적인 운항속력을 선정하여 효율적인 예부선 업무를 수행해야 할 것으로 판단된다.

• Bulletin of the Society of Naval Architects of Korea
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• v.31 no.4
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• pp.18-21
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• 1994

시제품을 만들어 본 후 대량 생산에 들어가는 여느 공업과는 달리, 조선공업에서는 시제품을 미리 만들어 볼 수가 없으므로 실선의 성능을 미리 추정하는 것은 참으로 중요한 과제 중의 하 나이다. 그 가운데 하나인 저항추진성능을 추정하는 데에는 통계해석 방법이 널리 쓰이고 있다. 여기서 통계해석은 모형시험 결과를 표본자료로 한 통계해석을 말한다. 실선의 저항추진성능을 추정하는 것이므로 실선 속력시운전 자료를 사용하는 것이 좋겠으나, 실선 속력시운전에서 정 확한 값을 얻는다는 것이 거의 불가능하므로 대부분 모형시험 값을 이용하곤 한다. 본 고에서는 기존에 발표된 여러 가지 도표와 회귀식을 요약하여 본 후, 표본자료를 이용하여 새로운 회귀 식을 만드는 과정을 소개하고자 한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.11a
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• pp.158-161
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• 2018

In this paper, the towing force is calculated for the LNG bunker barge. LNG bunkering barge is being developed as an infrastructure for the bunkering of LNG(Liquefied Natural Gas), an eco-friendly energy source. In the case of the LNG bunker barge, a self-propulsion is considered through retrofit from an operating point. Therefore, the LNG bunker barge is similar to the shape of the ship as compared to a towed barge, so a rule of the towed barge overestimates the towing force. In order to improve accuracy, the calm water resistance is calculated according to the ITTC 1978 method considering the wave resistance by the Rankine source method. The added resistance in waves is calculated using the modified radiated energy method considering the shortwave correction method of NMRI. The performance of the towing resistances through the calm water resistance and the added resistance in waves was compared with rules of the towed barge.

• Journal of Navigation and Port Research
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• v.42 no.6
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• pp.378-387
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• 2018

In this paper, the towing force for the LNG bunkering barge was investigated. Currently, LNG bunkering barge is being developed as an infrastructure for the bunkering of LNG (Liquefied Natural Gas), an eco-friendly energy source. In the case of the LNG bunkering barge, self-propulsion is considered through retrofit from an operating point. Therefore, the LNG bunkering barge's shape is similar to that of the ship as compared to a towed barge, so a rule of the towed barge overestimates the towing force. In order to improve accuracy, the calm water resistance was calculated using ITTC 1978 method which considers wave resistance by the Rankine source method. The added resistance in waves was calculated using the modified radiated energy method which considers the shortwave correction method of NMRI. The performance of the towing resistances through the calm water resistance and the added resistance in waves was compared to rules associated with towed barges.

• Journal of Navigation and Port Research
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• v.34 no.6
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• pp.417-422
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• 2010

In this study, the resistance performances of barge are analyzed by model tests and computation using CFD to investigate the flow characteristics around a barge in still water. The model tests are carried out in infinite depth in Inha Technical College Circulation Tank to observe the resistance and the numerical simulations based on VOF(Volume of Fluid) method are performed to analyze the flow around the barge. We have selected two barge models to investigate the flow characteristics according to the different type of barges. The experiments are carried out with the models from 5kts to 10kts(designed speed 7kts) considering the effect of adverse and favorable current. The numerical simulations are performed to analyze the flow and resistance characteristics of barge in the full loaded condition with the target speed and compared with the experimental data to confirm the reliability of the numerical method. The result was that the difference of resistance with 25% occurred at low speed and EHP increased rapidly from 7kts.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.4
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• pp.430-437
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• 2018

For a ship navigating in waves, added resistance, sway force and yaw moment due to waves differ from still water conditions, which affects the maneuverability of the ship. Therefore, it is important to estimate the sway force and yaw moment generated by waves. In this study, numerical simulations were carried out to calculate the hydrodynamic forces acting on a barge in still water and waves using CFD. Based on the results, the characteristics of course stability of a barge were investigated and analyzed. The hydrodynamic forces acting on the barge in waves were stronger than in still water, and it was confirmed that hydrodynamic forces become greater as wavelength becomes longer. In long wavelength regions, the (-) value of the yaw damping lever was larger than in still water. However, in short wavelength regions and when wavelength coincided with the length of the ship, values were smaller than in still water. In this region, it can be assumed that course stability improved. In other words, in long wavelength regions, the course stability of the barge was worse than in still water and short wavelength regions. Therefore, attention is required for safe navigation in long wavelength regions.

• Proceedings of the KIEE Conference
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• summer
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• pp.227-229
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• 2004

시대가 변화 하면서 선로손실 및 전압강하문제에 많은 관심을 가지게 되면서, 현재 사용중인 선로 정수값에 대한 고찰을 필요로 하게 되었다. 본 논문에서는 배전선로정수에 대한 현황 및 근거를 확인하고, 또한, 선종별로 장주의 배치에 따른 인덕턴스값 및 온도변화에 따른 교류저항값등에 대한 분석 내용을 소개하기로 한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2007.12a
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• pp.34-36
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• 2007

현재 모형선을 이용한 선형성능 검증방법에는 크게 2가지 방법이 있다. 첫째는 예인수조에서 예인전차를 이용하여 정수중에 배를 예인시켜 그에 따른 저항을 시험하는 방법이 있고, 둘째는 회류수조에서 배를 고정하여 물을 회전시켜 모형선의 저항을 측정하는 방법이 있다. 이와 같은 방법은 저속 및 대형선박을 검증하기 위해 계발된 방법들로 소형 고속어선 및 고속레저선박의 저항성능 평가를 수행하기 어려운 것이 현실이다. 예인전차의 예인속도와 회류수조 물의 유속이 소형 고속어선 및 고속레저선박의 속력에 미치지 못하기 때문이다. 따라서 고속을 요하는 선박의 저항성능 평가를 위해 새로운 방법 연구가 필요하다. 이에 고속선의 저항성능 시험을 위해 실 해상에서 일반 선박을 이용하여 예인하는 방법을 적용하여 저항시험을 수행하였으며 그에 맞는 시스템을 설계하였다.