• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.45-50
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• 2006

본 연구는 Manta형 무인잠수정(Manta-type Unmanned Undersea Vehicle)의 동안정성을 검토한 후에 이 데이터를 기초로 하여 6자유도 수치 시뮬레이션을 실시하였다. 또한, 수치 시뮬레이션을 통하여 각각의 유체력미계수가 UUV의 6자유도 운동에서 미치는 영향에 대하여 검토하였다. 민감도 해석(Sensitivity Analysis)을 위한 방법은 간접법(Indirect Method)을 사용하였다. 수학모델 및 유체력미계수의 추정은 손경호 등(2006)의 결과를 이용하여 수행하였다. 연구를 통하여 UUV의 조종운동 모델에서 각각의 유체력미계수가 가지는 상대적 중요도를 알 수 있었다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.11-12
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• 2014

본 연구에서는 일정속도로 항행하는 선박의 후미에서 20도의 각도로 진행하는 뒤파도가 존재할 경우, 선박의 무게중심 변화에 따른 안정성 해석에 대해 전산유체역학(CFD) 기술을 이용하여 운동 시뮬레이션을 수행하였다.

• Journal of Ocean Engineering and Technology
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• v.6 no.1
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• pp.29-42
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• 1992

자유표면하에 잠긴 복잡한 3차원 물체 주위의 흐름을 해소하기 위한 수치계산법이 TUMMAC(Tokyo Univ. Modified Marker And Cell)법을 기초로 하여 개발되었다. 임의물체의 no-slip 3차원 물체표면조건을 보다 간단히 처리하기 위하여 "porosity"라는 개념이 도입되었으며, 담수성에 잠겨 있는 해저돌출물 주위의 유동을 계산하여 그 응용성을 검토하였다. 돌출물 후방의 복잡한 와동들의 상호간섭이 잘 시뮬레이션 되었다.시뮬레이션 되었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.83-85
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• 2015

The Purpose of this paper was to carry out basic study on development of real-time submarine-hnadling simulator. The author adopt the Unmanned Undersea vehicle(UUV), which has taken the shape of manta[1]. They call here it Unmanned Undersea Vehicle(UUV). UUV is based on the same design concept as UUV called Manta Test Vehicle, which was originally built by the Naval Undersea Warfare Center, USA[1]. The present study deals with prediction of manoeuvring motion of UUV at general drift angles and large drift angles. The dynamic mathematical model with six degrees of freedom is revised and supplemented in order to describe accurately motion of UUV. The hydrodynamic derivatives related to motion are obtained from previous work[2].

• Journal of the Korea Society for Simulation
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• v.19 no.1
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• pp.13-22
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• 2010

This paper describes tagline PD control for reduction of motion for the heavy cargo(load) suspended by a floating crane. The equations of motion are set up considering the 6-degree-of-freedom floating crane and the 6-degree-of-freedom load based on multi-body system dynamics. The tagline mechanism is applied to floating crane to control motion of the heavy cargo(load). The winch, mounted on the deck of floating crane, is used to control the tension of tagline. To generate control force, PD control algorithm is applied. Numerical simulation and experiment is executed to verify the tagline control mechanism. The numerical simulation and experiment shows that the tagline control mechanism reduces the motion of the load suspended by a floating crane.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.11a
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• pp.100-102
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• 2023

항로추종성능은 자율운항선박(MASS)의 중요한 자율제어기능 중 하나이다. 이는 선박의 안전성을 보장하기 위해 중요하며, 자율운항선박의 설계 단계에서 사전 평가가 필수적이다. 본 연구는 자율운항선박의 항로추종성능 평가를 위한 전산유체역학(CFD) 모델과 LOS 알고리즘 연계 방안을 제안한다. 먼저, 자율운항선박의 정수 중 거리 이탈 편차를 이용한 항로 추종 성능 평가 모델 개발에 관하여 기술했다. 먼저, 항로 추종을 수행하는 선박 주변의 난류 흐름은 비압축성 뉴턴 유체의 가정하에 비정상 RANS(Reynolds Averaged Navier-Stokes) 법을 이용하여 수치적으로 계산되었다. 중첩격자계법을 CFD 모델에 적용함으로써 거리 이탈 편차를 이용하는 LOS(Line-of-Sight) 가이던스 알고리즘에 의한 타의 회전 및 이에 따른 선체의 6 자유도 움직임을 CFD 환경에서 구현하였다. 개발된 자유 항주 선박 CFD 모델을 이용하여 항로 추종 시뮬레이션 평가 결과, 설정된 항로에서 선박의 정수 중 항로 추종 제어는 파도, 조류, 및 바람과 같은 외부 교란의 부재로 LOS 알고리즘에 의한 우현/좌현 측 변침뿐만 아니라 직진 경로의 추종도 성공적으로 수행됨을 확인하였다. 선체, 프로펠러, 타의 복잡한 상호작용을 정도 높게 해석할 수 있는 자유 항주 선박 CFD 모델과 LOS 알고리즘의 결합은 자율운항선박의 항로 추종 성능 평가를 정량적으로 평가하는 데 기여할 것으로 기대된다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.4
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• pp.305-316
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• 2014

As avionics and mechanical devices have been developed, the size of unmanned aerial vehicle (UAV) is getting smaller. However, the complicated and accurate missions are provided to the UAV. Among various types of UAVs, quadrotors are widely used for their availability by virtue of simple structure and hovering function. However, the control of quadrotor is highly constrained, because the quadrotor is an under-actuated system which has only 4 actuator inputs. To deal with this under-actuated problem, a new quadrotor model with two more actuators in addition to the 4 propeller inputs is provided to make the system fully-actuated. For the proposed model, a controller is designed using feedback linearization methods. To validate the model and to verify the performance of the proposed controller, numerical simulation is performed.

• Journal of Navigation and Port Research
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• v.32 no.8
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• pp.603-609
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• 2008

Manta-type Unmanned Undersea Test Vehicle(MUUTV) is based on the same design concept as Unmanned Undersea Vehicle called Manta Test Vehicle(MTV), which was originally built and operated by the Naval Undersea Warfare Center(Lisiewicz et al., 2000, Sirmalis et al. 2001). The authors carried out the sensitivity analysis of the response of manoeuvring motion of MUUTV to changes in hydrodynamic derivatives, In order to calculate the sensitivity indices of hydrodynamic derivatives on MUUTV, the method by Sen(2000) was adopted Basically the dynamic mathematical model with six degrees of freedom by Feldman(1979) is used but a little revised, refered to Sohn et al.(2006) and some experiment in circulating water channel. Through the present research, some hydrodynamic derivatives of significance are found out, and also the numerical simulation using simplified mathematical model based on result of sensitivity analysis is ascertained to be enough for prediction of manoeuvring characteristics of MUUTV.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.6
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• pp.873-879
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• 2009

The steady breakers at an infant stage are investigated through the numerical simulation. The appearing condition and characteristics of the sub-breaking waves are reviewed by analysing bow waves. The instability analysis is possibly done through the relationship between the free-surface curvature and circumferential force, which is obtained from the momentum equations. Navier-Stokes equations are solved by a finite difference method where the body-fitted coordinate system, the wall function and the advanced mesh system are invoked. The numerical result shows that the gradient of M/$U_s$ is greatly influenced by the Froude number and the decrease of M/$U_s$ indicates that the flows are unstable. Additionally flows with plunging or spilling are simulated successfully, but the application of breakers to the severely broken wave still remains to be settled in the future.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.11
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• pp.2751-2757
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• 2015

To obtain the system requirement specification in the beginning of the precision guidance and control system development, the effectiveness and reliability analysis for the system are necessary. The main purpose of this research is to obtain the system requirement specification by carrying out the effectiveness analysis using the modeling and simulation(M&S) scheme. M&S model is constructed using 6-DOF dynamic model, environment model, guidanc -navigation & control model. Assume that the navigation sensor is consist of inertial navigation sensor(INS) and doppler velocity log(DVL), and the speed and direction of current is environment parameter. The effectiveness analysis is carried out using circular error probability(CEP) and variance analyze scheme. Also, the effectiveness analysis is utilized for cost-performance analysis considering the cost of commercial INS and DVL sensor. This paper shows the high-level INS and the low-level DVL configure a high price-performance integrated navigation system.