• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2020.11a
• /
• pp.78-79
• /
• 2020

국내 연안의 카페리선박의 고박안전성은 화물의 중량과 적재된 위치에서 발생할 수 있는 선체가속도를 기반으로 한 작용 외력과 고박장치의 고박력 비교를 통해 평가하고 있다. 국내 기준상의 선체가속도는 선박의 특성 및 항해조건의 반영이 없이 적용됨에 따라, 본 연구에서는 국내 연안 카페리선박의 선체가속도를 분석하고자 부산-제주를 통항하는 DWT 6,800톤급 선속 15.5 knots의 선박을 기준으로 선체의 4개 지점에서 총 12회의 가속도 계측을 수행하였고, 수치 시뮬레이션을 통하여 가속도 해석을 수행하였다. 가속도 비교 결과를 통하여 고박안전성 평가에 적용되어야 하는 가속도 적용 및 고박안전성 평가 방법에 대한 검토를 제시하고자 한다.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.26 no.6
• /
• pp.587-593
• /
• 2020

The securing safety of ferry ships on the domestic coast is evaluated by comparing the external force applied and the securing device based on the cargo weight and hull acceleration that can exist at the loaded position. The hull acceleration based on the domestic standard, which is the basis for securing safety evaluation, is applied without reflecting the characteristics of the ship and the sailing conditions. In this study, a total of 12 acceleration measurements were performed at four points of the hull of a ship with a DWT 6,800 ton class 15.5 knots passing through Busan-Jeju to analyze the hull acceleration of the domestic coastal ferry ship. Data were collected for the buoy. For a theoretical comparative analysis of the limited measurement results, the response amplitude operator (RAO) was analyzed through frequency-response analysis by numerical simulation, and acceleration analysis for the four points was performed using the RAO results. Based on the acceleration comparison, differences in the degree of each position were observed, but in the case of the Y-axis acceleration, the analysis was 1.81 m/s², and the measurement was 1.47 m/s². The analyzed simulation result was as high as 0.34 m/s². Moreover, analysis was performed at 22 % level, and measurement at 18 % level.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.27 no.4
• /
• pp.457-464
• /
• 2021

Cargo securing safety, which is one factor for the safe operation of car ferry ships, has been applied since 2015 and evaluated by comparing the hull motion and securing load capacity generated by waves. To ensure the safe operation of the 3700 ton class car ferry, it is important to analyze the hull acceleration motion based on the sea wave information of the navigation area to determine the cargo securing load that can prevent the movement of cargo. In this study, the meteorological information of three wave buoys installed in Busan and Jeju area was analyzed for the past 5 years. In addition, the hull acceleration was measured in actual sea conditions and compared to that of numerical simulations. Under the condition of a significant wave height of 2.5 m from Feb to Mar, except typhoon seasons, the lateral acceleration was observed to be 1.5 m/s² in real ship measuring and 1.8 m/s² in numerical calculation. It was analyzed to be less than 40% under general weather conditions compared to the high wave warning using an approximate formula for estimating the hull motion by wave height. The cargo securing safety proposed in this study will be widely used based on the actual measuring acceleration with the sea wave height.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2007.12a
• /
• pp.31-33
• /
• 2007

최근에 선박이 대형화, 고속화되면서 선수 충격파 영향으로 인하여 선체 또는 화물에 잦은 손상을 초래하기도 하고, 극단적인 상황에서는 선박이 절단되기도 한다. 본 논문에서는 내항성능 평가요소 중 하나인 상하가속도 값을 선교에 설치된 선체감시장치를 이용하여 해상상태별 변화량을 계측하고, 이를 모형시험 및 이론계산 결과와 상호 비교하였다. 또한 ITTC 에서 제시하는 내항성능 기준치와도 비교함으로써 실습선 한바다호의 내항성능을 확인하였다. 이러한 결과는 앞으로 경험할 수 있는 다양한 해상상태에서의 작업가능성 및 위험성 정도의 예측을 가능하게 함으로써 선박의 안전운항에 큰 도움이 될 것으로 판단되며, 또한 다양한 실선계측 자료를 통하여 조선소에서는 보다 우수한 성능의 선박 건조가 가능하리라 본다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.1
• /
• pp.47-54
• /
• 2014

Endurance of ship hull can be estimated by existing regulations and fatigue estimation methods. These can be applied to the hull materials that are recommended by ship regulations but can't be applied to new materials. In this study, structural force in the worst sailing condition is obtained by the acceleration measurement test of small polyethylene boat and the endurance of small polyethylene hull is estimated by rainflow cycle counting method and linear cumulative damage rule. Maximum Von-Mises stress on the polyethylene boat is 1.8MPa and much lower than the fatigue strength of at least 5.9MPa for the fatigue life of $1{\times}10^9$ cycles. Fatigue life of the polyethylene boat hull is estimated to be 6,229 years.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.29 no.4
• /
• pp.307-315
• /
• 2023

Korea controls the departure of vessels based on the Maritime Safety Act such that only ships with seaworthiness can navigate in bad weather, but scientific evaluation results and quantitative basis for the designation of ships subject to control are insufficient. Opinions for improvement are being raised for a reasonable departure control operation. The purpose of this study is to evaluate the adequacy of the current departure control standards through actual measurement of tugboats, which are the type of vessels subject to control when a wind and wave advisory is effective, and to present quantitative grounds for improvement of controls. A sensor was installed on the tugboat to measure the ship's three-axis motion and hull acceleration, and the hull motion performance was measured by operating in the sea area with a significant wave height of 3 m. The measured values were compared and analyzed based on seaworthiness evaluation factors and limit value standards. The actual ship was excluded from the current control standard according to tonnage, but as a result of the analysis, the pitch value exceeded the operation standard, and a risk to navigation safety existed. The results of this study suggest the need for additional actual measurement studies that can represent various ship types and specifications and review ship departure control targets.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2003.05a
• /
• pp.132-138
• /
• 2003

In order to evaluate properly ship motion relating to the berthing maneuver, the hydrodynamic forces acting on ship hull in berthing maneuver need to be estimated rightly. CFD has been employed for time-domain simulation of transient flow induced by Wigley model moving laterally from rest in shallow water. The numerical solutions successfully captured not only the characteristics of the transitional hydrodynamic forces but also some interesting features of the flow field around a berthing ship according to the water depth. In this paper, the consideration is carried out on the approximate formula based on the CFD results, which can estimate hydrodynamic forces especially lateral drag coefficient starting from the rest to the uniform movement.

• Journal of Navigation and Port Research
• /
• v.31 no.10
• /
• pp.905-910
• /
• 2007

As the ship is getting bigger and faster lately, ship's structure or cargoes might be often damaged and the ship might be cut in two in extreme conditions by a wave impact on its bow. In this paper, the vertical acceleration, which is one of factors for evaluating seakeeping performance, was measured under the various sea states by the hull stress monitoring system(HMS) on the bridge, and the result was compared with those of model test and theoretical studies. Then, we confirmed the seakeeping performance of T.S. HANBADA by comparing it with ITTC seakeeping criteria This result will be a great help for the safe navigation by making it possible to estimate the possibility of work and the amount of risk under the various sea conditions with which may be confronted, and the shipbuilding yard can be possible to construct the vessel with superior performance through these data measured on the actual ship.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.20 no.2
• /
• pp.228-233
• /
• 2014

In this paper, the motion performance in waves for the training ship Kaya of Pukyong National University is obtained by using a computer program based on Strip method. To guarantee the pleasant seafaring in ocean, the vertical acceleration of ship motion is calculated according to the location of the ship. The results of calculation by changes of ship speed are compared with the guideline of MSI(Motion Sickness Incidence). The degree of motion sickness is shown and discussed through the comparison between calculated vertical acceleration spectrum and MSI guideline. The computational results of MSI were as follow; when ship speed increased in the order of 5 knots, 10 knots, 12 knots and encounter angle became the bow quartering sea of $120^{\circ}$ compared to $180^{\circ}$ and $150^{\circ}$, the vertical acceleration values grew higher.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2022.06a
• /
• pp.401-402
• /
• 2022

해상 상태의 변화는 어선에 탑승하고 있는 선원들의 피로도, 인지능력, 활동성 및 숙련도 변화 등과 같은 현상이 발생한다. 어선의 동요가 심해지면 특히, 멀미 증상이 발생하게 되며 개개인의 작업수행 능력이 급격히 떨어진다. 본 연구에서는 3톤급, 7톤급, 10톤급, 20톤급 어선을 대상으로 하여 파랑 중 운동 성능을 평가하여, 실해역 조건으로 어선의 선내 위치별 수직가속도 성분을 선체 운동 계산법을 통하여 계산하였다. 어선의 크기별 정박상태에서 수직가속도 스펙트럼을 사용한 멀미의 정도를 표시하였으며, MSI 계산은 입사파 방향 180도, 150도, 120도, 90도, 60도, 30도, 0도로 수행하였다. 그 결과 특정 주파수에서 입사파 방향에 따른 멀미의 가능성이 나타났다.