• 대한조선학회논문집
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• 제50권4호
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• pp.232-239
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• 2013

This paper provides the structure of a Reynolds Averaged Navier-Stokes(RANS) based simulation method and its validation results for the ship motion problem. The motion information of the hull computed from the equations of motion is considered in the momentum equations as the relative fluid motions with respect to a non-inertial coordinates system. A finite volume method is used to solve the governing equations, while the free surface is captured by using a two-phase level-set method and the realizable k-${\varepsilon}$ model is used for turbulence closure. For the validation of the present numerical approach, the numerical results of the resistance and motion tests for DTMB 5415 at two ship speeds are compared against available experimental data.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.116-128
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• 2020

In the shipbuilding industry, three-dimensional (3D) templates play a key role in the completeness evaluation of shell plates with a large curvature in the shell-plate fabrication process. Currently, the information of 3D templates from a ship computer-aided design system is limited; thus, manufacturers depend on their experience to produce the templates manually. This results in the inaccuracy of templates in addition to increased production time. Therefore, if the pieces of the 3D templates can be produced automatically with accurate information, the lead time of the fabrication process can be reduced. In this study, we define a new type of template piece and develop methods for extending a boundary template and converting manufacturing information into numerical control machine input. In addition, based on the results of the study, we propose a production automation system for 3D template pieces. This system is expected to reduce the lead time of the fabrication process.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 The Third Asian Fuzzy Systems Symposium
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• pp.585-590
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• 1998

The purpose of this paper is to develop a neurofuzzy modeling & inference system which can determine principle dimensions and hull factors in an initial ship design. Neurofuzzy modeling & inference for a hull form design (NeFHull) applies the given input-output data to the fuzzy theory. NeFHull also deals the fuzzificated values with neural networks. NeFHull redefines normalized input-output data as membership functions and executes the fuzzficated information with backporpagation-neural -networks. A hybrid learning algorithms utilized in the training of neural networks and examining the usefulness of suggested method through mathematical and mechanical examples.

• 한국정보통신학회논문지
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• 제25권1호
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• pp.134-145
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• 2021

함정 추진제어시스템은 축계와 추진엔진의 과토크 및 과부하를 방지하면서 함정 작전요구성능을 만족할 수 있는 효율적인 제어로직 적용이 필수적이다. 이에 따라 함정 시운전 기간 중 추진제어기의 파라미터 값을 수정하는 이른바 튜닝(tuning)과정을 거쳐 제어체계를 최적화 하는 것이 일반적이다. 그러나 이러한 과정에서 초기 설정 값의 오차가 큰 경우 튜닝 시간이 과도하게 소요되거나 오버토크, 오버스피드 및 과출력으로 인해 추진 장비에 손상을 초래할 수 있다. 이에 본 논문에서는 함정 추진체계를 보호하면서 비교적 추진제어기 소프트웨어의 튜닝 경험이 적은 비숙련자도 함정 추진체계를 보호하면서 튜닝시간을 단축할 수 있는 프로세서 레버 제어기 적용을 제안한다. 프로세서 레버 제어기 성능 검증을 위해 시뮬레이션을 활용하여 프로세서 레버 제어기를 적용한 결과와 PI제어기만 적용한 결과를 비교하여 제어 특성 및 추진성능을 분석하였다. 시뮬레이션 결과 프로세서 레버 제어기 기능을 미적용 시 발생하였던 9.74%의 과도응답이 발생하지 않아 추진체계의 안정성을 높일 수 있었으나, 시스템의 응답성이 늦어짐에 따라 함정 추진성능(가속능력)이 감소하였다. 이러한 추진성능의 저하는 프로세서 레버 제어기의 파라미터 값을 조정하여 안정적으로 해결하였다.

• 해양환경안전학회지
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• 제23권6호
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• pp.754-758
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• 2017

본 논문에서는 선박의 안전운항을 위하여 안개 발생 시 엔진을 자동으로 제어하여 피해를 최소화하거나 회피할 수 있도록 자동 제어 시스템을 설계 및 제작 하였다. 제작된 동력 자동제어시스템은 ATmega128과 RPM감지회로를 사용하여 안개발생부에서 인위적으로 안개를 발생시켜 RPM의 변화량을 측정하였다. 이를 위하여 전체구성도를 작성하였으며 홀센서가 있는 모터를 사용하여 PWM 제어를 하도록 ATmega128에 Source code를 적용시켰다. 추후, 제작된 동력 자동제어장치를 통하여 실제 선박에서의 실험 및 안전성평가를 마련할 계획이다.

• 대한조선학회논문집
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• 제41권6호
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• pp.126-133
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• 2004

As the automation of ship production system proliferates, it is unavoidable to move the real machinery, facility, application software, and virtual environment from the heterogeneous data environment to the integrated one. However, it is a prevailing situation that each component operates under the different environment, due to the inability of interchanging the data in a structured manner between the components. The issue is obstacles to improvement of the application system. To facilitate seamless exchange of data among the manufacturing systems, STEP, PDML, and XML has been tried by other studies. This study has investigated how XML data can be applied to exchange the data among the ship production system components. XML data is applied to the forming shop in shipyard to overcome the present difficulties on sharing and exchanging of the information. An example of forming information is represented by XML to demonstrate the feasibility of the proposed approach. In addition, an application of XML information applicable to virtual factory and electronic work order sheet is included.

• 대한조선학회논문집
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• 제56권2호
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• pp.128-134
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• 2019

In shipbuilding, accurate fabrication of curved hull plates is one of the most important steps, since the shape of ship hull, which is very critical in the overall performance of a ship, is a collection of such plates. The curved hull plates forming process requires a significant amount of time by skilled workers in shipbuilding. In general, the workers cause thermal distortion in the plate and forming initial shape using gas heat source. So shipbuilding companies need skilled workers who have long experience. To solve the problem, a lot of researchers tried to develop automation system for curved hull plates. In this paper, we propose automatic heating system with gantry robot, high frequency induction heater to replace the gas heat source and automatic measurement system. We apply the system to forming concave type plate that is actually used in ship manufacturing. In addition, a system was developed to automatically generate heating information, such as the heating location and the heating speed, for actual heating process. Then the system was applied to the actual heating material. It is shown that the proposed triangle heating pattern makes desired concave shape successfully. The induction heating system showed that it can be used for automation system of curved hull plates forming process replacing gas heat source.

• Journal of Ship and Ocean Technology
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• 제10권4호
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• pp.34-48
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• 2006

The visual observation of wave condition depends on the observer's skill and experience. Also, the environmental conditions such as light and cloud heavily influence the visual measurement. In the speed test of sea trial, the wave measurement should be objective and accurate. In this paper, the problems of visual measurement and their effects on speed test are described. To overcome those problems, we developed the wave measurement system using commercial marine X-band radar, WaveFinder. The system installed at inland base was calibrated by waverider buoy and then the system's operability was defined. Onboard tests had also been performed three times for formal wave measurement to correct the ship speed. The results illustrated very good agreement with visual observation by experts. It can be concluded that the system would be useful to measure wave and swell information for the sea trial, irrespective of day and night.

• International Journal of Naval Architecture and Ocean Engineering
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• 제5권2호
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• pp.188-198
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• 2013

In constructing a collision avoidance system, it is important to determine the time for starting collision avoidance maneuver. Many researchers have attempted to formulate various indices by applying a range of techniques. Among these indices, collision risk obtained by combining Distance to the Closest Point of Approach (DCPA) and Time to the Closest Point of Approach (TCPA) information with fuzzy theory is mostly used. However, the collision risk has a limit, in that membership functions of DCPA and TCPA are empirically determined. In addition, the collision risk is not able to consider several critical collision conditions where the target ship fails to take appropriate actions. It is therefore necessary to design a new concept based on logical approaches. In this paper, a collision ratio is proposed, which is the expected ratio of unavoidable paths to total paths under suitably characterized operation conditions. Total paths are determined by considering categories such as action space and methodology of avoidance. The International Regulations for Preventing Collisions at Sea (1972) and collision avoidance rules (2001) are considered to solve the slower ship's dilemma. Different methods which are based on a constant speed model and simulated speed model are used to calculate the relative positions between own ship and target ship. In the simulated speed model, fuzzy control is applied to determination of command rudder angle. At various encounter situations, the time histories of the collision ratio based on the simulated speed model are compared with those based on the constant speed model.

• 대한전자공학회논문지TC
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• 제49권5호
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• pp.99-106
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• 2012

함정의 운용 효율성을 높이기 위해서 한국 해군은 음성통신위주의 함내외 통합통신체계(ICS:Integrated Communication System)을 운용해 오고 있으며, 최근에는 음성, 영상, 문자 등이 포함된 멀티미디어 통합통신망에 대한 적용을 고려하고 있다. 본 논문은 함정용 멀티미디어 통합통신망을 구축하기 위한 기초연구로써 한국 해군의 함정 내 여러 통신망 중에서 통합통신망에 적용할 통신망을 구분하고, 구분된 통신망에서 운용중인 멀티미디어 트래픽의 종류 및 특성들을 고찰한다. 아울러 ICS 통신교환기에서의 트래픽 입력소스 수에 따른 링크용량을 예측하기 위해서 트래픽 다중화 모델을 제안하고, 한국 해군의 주요 함정 별 트래픽의 링크용량 산출 및 통합 트래픽을 분석한다.