• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.6
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• pp.98-104
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• 1999

As the accuracy of manufactured goods needed high accuracy processing has made the efficiency of NC and measurement technology development, the innovation of machine tools has influence the development of the semi-conductor and optical technology. The movement errors can be expressed in terms of yaw, roll an pitch etc. In the case of expanding the error range, static, dynamic and servo gain errors can be included. Machining center might have twenty-one movement errs including three types of joint errors. Those errors have been measured on the condition of just loading of standard table. Regarding these measuring methods, the mechanical compliance of the structure has not been considered. In this paper, therefor, the influences of the additional load on the positioning accuracy are investigated. The results and the techniques proposed in this study can be considered very effective and useful to compensate more correctly the positioning motion.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.92-92
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• 2000

Helicopter offer the signigicant advantage over traditional air vehicles, in that the provide extended maneuverability, such as vertical climb, hovering, longitudinal and lateral flight, hovering turns and bank turns. But helicopter have the strong cross couplings and nonlinearities for each lateral, longitudinal and rotational motion mutually. However, it is possible to ignore this couplings for the hovering condition, so using this properties we can control the attitude of helicopter. That is, by implementing the dynamic of each rotational axis(roll, pitch, yaw) of independent mutually, 3-DOF(degree of Freedom) attitude control for the helicopter is possible. In this paper, we identify decoupled input-coutput relations of each three rotational axis about the helicopter mounted on the 3-DOF gimbal by experiment, and on these basis implement 3-DOF attitude controller using the PID control method.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.6
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• pp.470-476
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• 2016

This paper proposes a practical algorithm for the reduction of measurement errors due to drift in a micro-electromechanical system (MEMS) gyros that are used for a mobile robot. Any drift in a MEMS gyro will cause an unbounded growth of errors in the estimation of heading, which makes it nearly useless in applications that require high accuracy over a long operating time. In proposed method, maneuvers of a cleaning robot are observed through encoders' measurement process and a decision to correct bias drift will be made if necessary. The method used in this paper is called the "heading estimation filter". To evaluate the accuracy of the proposed method, a comparison was made between the estimation of the heading of the cleaning robot and one from a motion capture system.

• Journal of Ocean Engineering and Technology
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• v.11 no.3
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• pp.100-106
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• 1997

Despite various devices have been developed and applied to stabilize the yaw motion, the superiority of twin skeg over other equi-functioned appendages has been recognized so far. In many cases, these skegs were installed with insufficient study and analysis for design, and this leads to the worse performance of their resistance and course keeping than required. Experimental studies on the effect of various kinds of anti-yawing skegs to the course keeping stability and on the additional resistance caused by them were carried out in the circulating water channel(CWC) at Chosun University(CU). Course keeping stability tests for four different size of skegs, resistance tests for three different shapes of skeg(including deformed skegs) were performed systematically. And the effect of angle of skegs on resistance was studied at the final stage.

• Advances in aircraft and spacecraft science
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• v.6 no.5
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• pp.371-389
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• 2019

The implementation of a robust $H_{\infty}$ Control, which is numerically efficient for uncertain nonlinear dynamics, on longitudinal and lateral autopilots is realised for a quarter scale Piper J3-Cub model accepted as an unmanned aerial vehicle (UAV) under the condition of sensor noise and disturbance effects. The stability and control coefficients of the UAV are evaluated through XFLR5 software, which utilises a vortex lattice method at a predefined flight condition. After that, the longitudinal trim point is computed, and the linearization process is performed at this trim point. The "${\mu}$-Synthesis"-based robust $H_{\infty}$ control algorithm for roll, pitch and yaw displacement autopilots are developed for both longitudinal and lateral linearised nonlinear dynamics. Controller performances, closed-loop frequency responses, nominal and perturbed system responses are obtained under the conditions of disturbance and sensor noise. The simulation results indicate that the proposed control scheme achieves robust performance and guarantees stability under exogenous disturbance and measurement noise effects and model uncertainty.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.786-793
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• 2021

In this study, a parametric investigation is performed using CFD for towing stability and loads according to the forward and aft slope angles of a barge-shaped FPSO. The forward slope angle is considered in a range of 30-60° and the aft slope is examined in a range of 20-50°. As a result of a comparative study based on CFD towing simulations, it is found that the yaw motion is damped out and stabilized when the aft slope is more than 40° regardless of the forward slope angle. The vortex contours in the y-axis plane near the aft slope are analyzed and it is observed that the vortex developed at the bottom knuckle is bent upward along the aft slope when the aft slope is less than 40°, and completely fallen from the bottom knuckle when the aft slope is more than 40°. Based on the results, a guide to forward and aft slope angles of a barge-shaped FPSO is presented from a practical point of view considering towing stability as well as towing load.

• The Journal of the Korea Contents Association
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• v.16 no.8
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• pp.427-434
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• 2016

This paper focuses on a real-time hardware processing by implementing the ARM Cortex-M4 based embedded system, using a conversion algorithm from a muscular sense to both visual and auditory elements, which recognizes rotations of a human body, directional changes and motion amounts out of human senses. As an input method of muscular sense, AHRS(Attitude Heading Reference System) was used to acquire roll, pitch and yaw values in real time. These three input values were converted into three elements of HSI color model such as intensity, hue and saturation, respectively. Final color signals were acquired by converting HSI into RGB color model. In addition, Three input values of muscular sense were converted into three elements of sound such as octave, scale and velocity, which were synthesized to give an output sound using MIDI(Musical Instrument Digital Interface). The analysis results of both output color and sound signals revealed that input signals of muscular sense were correctly converted into both color and sound in real time by the proposed conversion method.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2007.12a
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• pp.75-76
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• 2007

A mis-handling of the ship operators show high rate among the whole marine accidents. Since the port conditions have been getting worse. also as her size and speed increase, collision risk has been increased so that ship needs the automatic control system for collision. From that purpose, this research has been proceeded. The research has based on the MMG mathematical model, used Surge-Sway-Yaw motion equation, the information from the position and estimated time of collision point (DCPA and TCPA) to determine the collision risk with Fuzzy theory. To verify this system, ship was simulated when the ship encountered multitude of ships around the coast. The simulation result shows good application in avoiding ship collisions around the coast.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.6
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• pp.648-657
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• 2014

This paper is about the study on a newly developed small waterproofed 4-axis robot arm and the analysis of its kinematics and dynamics. The structure of robot arm is designed to have Pitch-Pitch-Pitch-Yaw joint motion for inspection using a camera on itself and the joint actuator driving capacity are selected and the joint actuators are designed and test for 10m waterproofness. The closed-form solution for the robot arm is derived through the forward and inverse kinematics analysis. Also, the dynamics model equation including the damping force due to the mechanical seal for waterproofness is derived using Newton-Euler method. Using derived dynamics equation, a sliding mode controller is designed to track the desired path of the developed robot arm, and its performance is verified through a simulation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.12
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• pp.1579-1584
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• 2011

This paper discusses an energy system that can convert wave energy into electrical energy. This wave energy generation system is movable and has 12 arms and one generator. A multibody dynamic model for this system is established by using kinematic constraints. A gear mechanism, several kinematic constraints, and force elements are included in the model. Wave forces are obtained numerically from the time domain formulation based on the Morison equation. The MSC/ADAMS program is employed to carry out dynamic analysis of the wave energy generation system. The dynamic behavior responses of this system are analyzed for design verification. According to the results of the dynamic analysis, the yaw motion is relatively stable and kinetic energy sufficient to generate electrical energy is obtained when the wave height exceeds 1m.