• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.5
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• pp.511-518
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• 2016

The dynamic positioning system (DPS) maintains an offshore vessel's position and heading under various environmental conditions by using its own thrust. DPS is regarded as one of the most important systems in offshore vessels. So, efficient operation and maintenance of the DPS are important issues. To monitor the DPS, it is necessary to define an appropriate key performance indicator (KPI) that can express the condition of the DPS from the perspective of operational efficiency and maintenance. In this study, a new KPI for the DPS is proposed considering the efficiency of the machinery and controller, the energy efficiency, and the environmental conditions in which the DPS is operated. The KPI is defined as a function of control deviation, energy consumption, and environmental load. A normalization factor is used to normalize the effect of environmental load on the KPI. The KPI value is calculated from DPS simulation and model test data. The possibility of applying the KPI to monitoring of DPS condition is discussed by comparing the values. The result indicates the feasibility of the new KPI.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.10a
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• pp.44-46
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• 2014

최근 DPO (Dynamic Positioning Operator) 자격증을 취득하고자 하는 해기사가 급증하고 있다. 그러나 우리나라에는 취득과정에 필수적인 승선실습을 제공할 수 있는 선박이 거의 없기 때문에 취득까지 많은 시간과 노력을 필요로 하게 되며, 때로는 중도에 포기하는 경우도 발생하고 있다. 이러한 어려움을 완화하고 보다 더 많은 해기사가 DP 선박에 진출할 수 있도록 하기 위하여 DPS (Dynamic Positioning System)를 설치한 실습선이 적극 검토되고 있다. 이러한 요구에 발맞추어 이 논문에서는 실습선에 탑재할 DPS의 요건에 대하여 제안한다.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.768-783
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• 2020

Typically, a Dynamic Positioning System (DPS) uses a PID feed-back system, and it often adopts a wind feed-forward system because of its easier implementation than a feed-forward system based on current or wave. But, because a ship's drifting motion is caused by wind, current, and wave drift loads, all three environmental loads should be considered. In this study, a motion predictive control for the PID feedback system of the DPS is proposed, which considers the three environmental loads by utilizing predicted drifted ship positions in the future since it contains information about the three environmental loads from the moment to the future. The prediction accuracy for the future drifted ship position is ensured by adopting deep learning algorithms and a replay buffer. Finally, it is shown that the proposed motion predictive system results in better station-keeping performance than the wind feed-forward system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.718-724
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• 2017

Considerable efforts have been made to expand the boundaries of domestic offshore plant industries, which have focused on the construction of the structures, to the engineering field. On the other hand, time domain analysis, which is one of the most important areas in designing floating offshore plants, relies mainly on the information given by foreign companies. As an early design of the Dynamic Positioning System (DPS) is mostly conducted by several specialized companies, domestic ship builders need to spend time and money to reflect the analysis into the hull shape design. This paper presents the framework required to analyze time domain performance of floating type offshore structures, which are equipped with DPS. To easily perform time domain analysis, framework generates the required input data for the solver, and is modularized to test the control algorithm and performance of a certain DPS. The effectiveness of the developed framework was verified by a simulation with a model ship and the total time for the entire analysis work was reduced by 50% or more.

• Journal of Power System Engineering
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• v.16 no.2
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• pp.66-74
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• 2012

In this paper, the authors propose a new approach to control a barge type surface vessel. It is based on the Dynamic Positioning System(DPS) design. The main role of barge ship is to carry and supply the materials to the floating units and other places. To carry out this job, it should be positioned in the specified area. However sometimes the thrust systems are installed on it, and in general the rope control by mooring winch system is used. It may be difficult to compare the control performances of two types. If we consider this problem in point of usefulness, we can easily find out that the winch control system is more useful and applicable to the real field than the thrust control system except a special use. Therefore, in this paper we consider a DPS design problem which can be extended to the many application fields. The goal of this paper is twofold. First, the sliding mode controller (SMC) for positioning the our vessel is proposed. Especially, in this paper, a robust stability condition is given based on descriptor system representation. In the result, the sliding mode control law guarantees to keep the vessel in the defined area in the presence of environmental disturbances. And second, the thrust allocation problem is solved by using redistributed pseudo-inverse (RPI) algorithm to determine the thrust force and direction of each individual actuator. The proposed approach has been simulated with a supply vessel model and found work well.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.10a
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• pp.31-33
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• 2014

최근 동적위치제어시스템 (Dynamic Positioning System, DPS)을 설치한 선박과 해양구조물이 늘어나면서 이 시스템을 운영하는 DPO (Dynamic Positioning Operator) 자격증을 취득하고자 하는 해기사가 급증하고 있다, 특히 2010년 STCW Manila Amendments에 DPO 자격과 관련된 사항이 Code B에 채택됨으로서 DPO 관련 자격기준이 급변하고 있다. 그러나 아직 우리나라에는 DPO 자격과 관련된 교육훈련제도가 정비되어 있지 않음은 물론 자격증 취득을 위한 교육훈련기관도 전무한 실정이다. 이 논문에서는 DPO 양성제도의 현황을 고찰한 후 이 제도를 효율적으로 도입하기 위한 방안을 제안하였다.

• Journal of Navigation and Port Research
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• v.39 no.3
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• pp.149-156
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• 2015

The Dynamic Positioning System consists of 7 elements which are namely Power system, Human machine interface, DP Computer, Position Reference System(PRS), Sensors, Thruster system and DP Operator. Incidents like loss of position(LOP) on DP vessel usually occur due to errors in these 7 elements. The purpose of this study is to find out safety operation method of DP vessel through qualitative and quantitative analyze of DP LOP incidents which are submitted to IMCA every year. The 612 DP LOP incidents submitted from 2001 to 2010 were analyzed to find out the main cause of the incidents and its rate among other causes. Consequently, the highest rate of incidents involving DP elements are PRS errors. DP computer, Power system, Human error and thruster system came next. The PRS has been analyzed and a flowchart was drawn through expert brainstorming. Also, the conditional probability has been analyzed through Bayesian Networks based on this flowchart. Consequentially, the main causes of drive off incidents were DGPS, microwave radar and HPR. Also, this study identified the main causes of DGPS errors through Bayesian Networks. These causes are signal blocked, electric components failure, relative mode error, signal weak or fail.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.10a
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• pp.28-30
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• 2014

Dynamic Positioning System(DPS)은 그 신뢰성 및 대체 시스템에 따라 IMO 및 각 선급에서 3개의 class(등급)로 나누고 있다. IMO MSC/Circ 645에 의하면 DPS는 Class 1, 2, 및 3로 나뉘어 있으며 등급이 높을수록 좀 더 신뢰성 있고 안전하게 DP 선박을 운용할 수 있다. 이러한 DPS의 등급은 DP 선박을 건조할 때 그 선박의 사용 목적 및 필요성 신뢰도에 따라 건조되고 있으나 최근에는 이미 건조되어 있는 DP 선박의 등급을 개조를 통해 변경하여 사용하기도 한다. 본 연구에서는 DP Class 1선박을 DP Class 2 선박으로 변경하기 위해서는 어떠한 IMO 및 선급 요건의 만족이 필요하며 이를 위해서 어떠한 설비의 추가가 필요한지를 알아보고 이를 실제 사례를 통해 확인 및 검증해 본다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2015.07a
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• pp.57-59
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• 2015

심해에서의 유전개발이 활성화되면서 이러한 개발에 필수적인 장비인 동적위치제어시스템 (Dynamic Positioning System, DPS)을 설치한 선박 또는 해양구조물의 수요도 폭발적으로 증가하고 있으며, 이에 따라 DPS 운영에 필수적인 DPO (Dynamic Positioning Operator) 자격증을 취득하고자 하는 지원자도 매년 급속하게 증가하고 있다. 그러나 DPO 교육훈련과정은 강제요건이 아니며, 따라서 엄정한 자격증명 및 검증이 어려운 실정이다. 특히 매년 2000건 이상의 신규면허를 심사하고 발급하는 것은 물론 기존 면허자에 대한 재검증 절차도 수행하여야 하는 현재의 상황으로 볼 때 효율적인 DPO 양성을 기대하기는 어려운 실정이다. 이 연구에서는 보다 이러한 문제점을 개선하여 보다 더 효율적이면서도 엄정한 DPO 양성을 위한 제도개선을 제안한다.

• Journal of the Korean Institute of Gas
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• v.3 no.2 s.7
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• pp.62-69
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• 1999

This paper presents a design method of dynamic positioning control system(DPS) for floating Platform with rotatable and retractable thrusters using H$\infty$ servo control design method. The norm band of uncertainty is captured by multiplicative perturbation between nominal model and reduced order model. A controller robust to the uncertainty is designed applying H$\infty$ synthesis. The control law satisfying robust stability and nominal performance condition is determined through the mixed sensitivity approach. The control algorithm was evaluated on the basis of computer simulation for a proposed DPS design method and experiments was carried out with an image processing method for measurement of DPS position in a water tank The results of overall experiments show that proposed control method will be good to keep at a specified position. And they are compared with the experimental results by LQG synthesis and H$\infty$ optimal control design method.