• 한국해양공학회지
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• 제32권1호
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• pp.9-20
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• 2018

The present study deals with the conceptual design of a motion reduction device for a floating wave-offshore wind hybrid power generation platform. A damping plate attached to the bottom of a column of a large semi-submersible is introduced to reduce the motion of the platform. Performance analyses on various shapes and configurations of damping plates were performed using the potential flow solver, and the appropriate configuration and size of the damping plate were selected based on the numerical results. In order to see the effect of viscous damping, a small scale model test was performed in a 2D wave flume. The performances of five different damping plates were measured and discussed based on the results of free decay tests and regular wave tests.

• Nuclear Engineering and Technology
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• 제53권7호
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• pp.2251-2260
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• 2021

The motion control of the divertor maintenance system of the China Fusion Engineering Test Reactor (CFETR) was studied in this paper, in which CFETR Multi-Functional Maintenance Platform (MFMP) was simplified as a parallel robot for the convenience of theoretical analysis. In order to design the motion controller of parallel robot, the kinematics analysis of parallel robot was carried out. After that, the dynamic modeling of the hydraulic system was built. As the large variation of heavy payload on MFMP and highly nonlinearity of the system, A Fuzzy-PID controller was built for self-tuning PID controller parameters by using Fuzzy system to achieve better performance. In order to test the feasibility of the Fuzzy-PID controller, the simulation model of the system was built in Simulink. The results have showed that Fuzzy-PID controller can significantly reduce the angular error of the moving platform and provide the stable motion for transferring the divertor.

• Structural Engineering and Mechanics
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• 제63권1호
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• pp.37-46
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• 2017

This paper is concerned with the numerical study on the resonance response of a rigid spar-type floating platform in coupled heave and pitch motion. Spar-type floating platforms, widely used for supporting the offshore structures, offer an economic advantage but those exhibit the dynamically high sensitivity to external excitations due to their shape at the same time. Hence, the investigation of their dynamic responses, particularly at resonance, is prerequisite for the design of spar-type floating platforms which secure the dynamic stability. Spar-type floating platform in 2-D surface wave is assumed to be a rigid body having 2-DOFs, and its coupled dynamic equations are analytically derived using the geometric and kinematic relations. The motion-variance of the metacentric height and the moment of inertia of floating platform are taken into consideration, and the hydrodynamic interaction between the wave and platform motions is reflected into the hydrodynamic force and moment and the frequency-dependent added masses. The coupled nonlinear equations governing the heave and pitch motions are solved by the RK4 method, and the frequency responses are obtained by the digital Fourier transform. Through the numerical experiments to the wave frequency, the resonance responses and the coupling in resonance between heave and pitch motions are investigated in time and frequency domains.

• 한국해양공학회지
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• 제32권4호
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• pp.222-227
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• 2018

Most underwater acoustic arrays for low frequency operation are deployed vertically, but a mid-range frequency horizontal array system is being developed by the Korea Research Institute of Ships and Ocean Engineering (KRISO). The horizontal array platform is deployed underwater and kept in place by weather vaning mooring. This is essential because it is nearly impossible to keep a submerged body at a given position in the water without any external force. Hence, the horizontal array platform can maintain the desired position in the presence of a weak tidal current. The objective of this study is to design an underwater platform that can maintain its horizontal position in a weak current. First, the authors investigated various virtual models, selected one of the models, and performed a small model test of the selected model at a basin. We calculated the external forces associated with the 2D motion, and then we conducted a large basin test followed by a circulation water channel test for the manufactured array platform. The results of the simplified 2D motion calculation essentially matched the results of the underwater test.

• 문화기술의 융합
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• 제1권1호
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• pp.73-77
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• 2015

기존의 스포츠 시뮬레이터 제품들은 모션 플랫폼의 운동과 간단한 시각적 콘텐츠를 이용한 실감 표현에 집중되어 있고 놀이위주의 적용에 국한되어 있어, 사용자가 체감할 수 있는 오감 자극효과가 낮아 고실감 적용에는 부족하며, 전문 콘텐츠 부재로 인해 교육용 스포츠 시뮬레이터로서의 적용은 아직 어렵다. 본 연구에서는 다종목 교환이 가능한 다축 공통 플랫폼과 교환식 스포츠 모듈로 분리하여 공통 플랫폼의 운동 자유도를 4자유도(Surge, Sway, Heave, Yaw) 운동을 할 수 있도록 스포츠 플랫폼을 설계하였다. 이 플랫폼은 안정성을 보장하고 간섭을 최소화하는 데 목적이 있다. 이 플랫폼에 탑재되는 교환식 스포츠 모듈의 운동 자유도는 2자유도(Roll, Pitch)로 승마, 요트와 같은 다양한 운동이 적용이 가능하고, 독립적인 회전 2자유도의 체감형 시뮬레이터의 구현이 가능하도록 하였다.

• 한국항해항만학회지
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• 제30권9호
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• pp.729-734
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• 2006

The authors aim to establish the theory necessary for developing the free gyroscopic compass and focus on mainly two points. One is to suggest north-finding principle by the angular velocity of the earth's rotation, and the other is to suggest orthogonal coordinate transformations of the motion rate of the spin axis, which transforms the components of motion rate in the free gyro frame into those in the platform frame and that this transformed rate is, in turn, transformed into the NED(north-east-down) navigation frame. Subsequently, ship's heading is obtained by using the fore-aft and athwartship components of the motion rate of the spin axis in the NED frame. In addition it was found how to solve the transformation matrix necessary for transforming each frame.

• 전기학회논문지
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• 제66권1호
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• pp.186-193
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• 2017

KOSMOS is Korea Open Source MOtion System which is developed based on general purpose hardware and open source software. It is aiming at IEC 61131-3 standard. Real-time ethernet has several advantages for motion control system and distributed control system. So, considering this advantages, KOSMOS has the network interface made up of Real-time ethernet, EtherCAT. In this paper, we explain the KOSMOS platform, the performance for real-time task and show the real case applying KOSMOS platform in manipulator control system.

• 반도체디스플레이기술학회지
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• 제22권4호
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• pp.172-178
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• 2023

With the expansion of metaverse content and hardware platforms, various interactions in the virtual world have been built, raising expectations for an increase in immersion which is a major element of the metaverse. However, among hardware platforms that increase virtual immersion elements, the typical HMD platform can be a barrier to new user inflows due to its high cost. Thus, this paper focused on improving virtual-to-real interactions by extracting motion data using relatively inexpensive webcam equipment in PC environments, utilizing Unity game engines, Photon unity network, multi-platform implementations, and Barracuda neural network inference libraries.

• Wind and Structures
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• 제24권4호
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• pp.333-350
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• 2017

Differing from the fixed-type, the dynamic motion of floating-type offshore wind turbines is very sensitive to wind and wave excitations. Thus, the sensing and monitoring of its motion is important to evaluate the dynamic responses to the external excitation. In this context, a monitoring system for sensing and processing the wind-induced dynamic motion of spar-type floating offshore wind turbine is developed in this study. It is developed by integrating a 1/00 scale model of 2.5MW spar-type floating offshore wind turbine, water basin equipped with the wind generator, sensing and data acquisition systems, real-time CompactRIO controller and monitoring program. The scale model with the upper rotatable blades is installed within the basin by means of three mooring lines, and its translational and rotational motions are detected by 3-axis inclinometer and accelerometers and gyroscope. The detected motion signals are processed using a real-time controller CompactRIO to calculate the acceleration and tilting angle of nacelle and the attitude of floating platform. The developed monitoring system is demonstrated and validated by measuring and evaluating the time histories and trajectories of nacelle and platform motions for three different wind velocities and for eight different fairlead positions.

• 한국생산제조학회지
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• 제19권2호
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• pp.171-177
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• 2010

This paper presents the development of a new 6-DOF parallel-kinematic motion simulator. The moving platform is connected to the fixed base by six P-S-U (Prismatic-Spherical-Universal) serial chains. Comparing with the well-known Gough-Stewart platform-type motion simulator, it uses commercialized linear actuators mounted at the fixed base whereas a 6-UPS manipulator uses telescopic linear ones. Therefore, the proposed motion simulator has the advantages of easier fabrication and lower inertia over a 6-UPS counterpart. Furthermore, since most forces acting along the legs are transmitted to the structure of linear actuators, smaller actuation forces are required. The inverse position and Jacobian matrix are analyzed. In order to further increase workspace, inclined arrangement of universal joints is introduced. The optimal design considering workspace and force transmission capability has been performed. The prototype motion simulator and PC-based real-time controller have been developed. Finally, position control experiment on the prototype has been performed.