• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.48 no.5
• /
• pp.249-256
• /
• 1999

This paper describes static characteristics analysis of linear pulse motor(LPM) with two permanent magnets. Linear pulse motors are finding a wide range of application for the Factory-Automation or the Office-Automation. Typically, LPM provides for a reliable and precise control of position, velocity, or acceleration without using a closed-loop system. Some of the advantages of LPMs are ease of control, step multiplication, static and dynamic positioning, and locking force. The flux density and thrust of LPM is computed by the FEM and magnetic equivalent circuits which considered the magnetic nonlinear phenomena. The result of characteristics analysis are shown as the flux, the air gap reluctance and the thrust. The velocity and position characteristics as a function of unit step input is measured. To estimate the unit step response charecteristic of LPM, the simulation results by Matlab and the experimental results is compared.

• Proceedings of the KIEE Conference
• /
• 1996.07b
• /
• pp.977-979
• /
• 1996

This paper presents an algorithm to control the undesirable sway of a suspended load in the crane system that has a trade-off between positioning the load and suppressing the sway of the load. The aim is to transport the load to a specified place with small sway angle as quickly as possible. Dynamic model is based on a simple pendulum driven by a velocity drive that is mostly used for actuating a trolley in industry. Proposed algorithm is composed of two parts : one is a off-line optimal trajectory generator, the other on-line tracking control. The former produces optimal trajectories minimizing energy under the speed constraint of velocity drive. The latter controls outputs to track the generated trajectories. Digital simulations and experiments are performed on a pilot crane to demonstrate the performance of the proposed control algorithm.

• Proceedings of the KIEE Conference
• /
• 1998.11a
• /
• pp.186-188
• /
• 1998

This paper describe the dynamic equation of Linear Pulse Motor(LPM)and the method of microstep drive and newly proposed control method for Linear Pulse Motor(LPM). A microstep drive is generally used for the high resolution positioning system. But high thrust distortion and imbalance in LPM make torque ripple that cause position error in microstep drive. In this paper the new control method is proposed and applied to hybrid LPM which is made by KERI. In the experimental results. it is shown the validity of the proposed control scheme.

• Journal of Advanced Marine Engineering and Technology
• /
• v.29 no.2
• /
• pp.236-242
• /
• 2005

Dynamic Positioning(DP) system maintains ship's position (fixed location or predetermined track) exclusively by means of CPPs and thrusters. To generate the control input adequate to various situation an integrated controller for CPPs and thrusters is required. The integrated controller is composed of a thrust calculation algorithm and a thrust allocation algorithm. The thrust calculation algorithm generates thrusts in the surge direction and the sway direction from the desired forward and lateral speed and generates a moment about the yaw axis from desired heading angle. The thrust allocation algorithm allocates the generated thrusts and moment to each CPP and thruster. Computer simulations are executed to confirm the effectiveness of the suggested controller.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2004.05a
• /
• pp.1529-1532
• /
• 2004

A Mobile Ad Hoc NETwork (MANET) is a collection of wireless mobile nodes that forms a temporary network without the need for any existing network infrastructure or centralized administration. Therefore, such a network is designed to operate in a highly dynamic environment due to node mobility. In mobile ad hoc network, frequent topological changes cause routing a challenging problem and without the complete view of the network topology, establishing the shortest path from the source node to the destination node is difficult. In this paper, we suggest a routing approach which utilizes location information to setup the shortest possible path between the source node and the destination node. Location information is obtained through Global Positioning System (GPS) and this geographical coordinate information of the destination node is used by the source node and intermediate nodes receiving route request messages to determine the shortest path to the destination from current node.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2022.11a
• /
• pp.164-165
• /
• 2022

자율운항선박(Maritime Autonomous Surface Ship)의 개발과 도입은 해양 분야의 4차 산업 시대를 이끄는 가장 중요한 기술과 변화이다. 자율운항선박은 해양 사고의 발생 원인 중 가장 높은 비중을 차지하는 인적 요소를 줄이기 위해 인간의 개입 없이 독립적으로 운항하는 선박을 일컫는다. 인간의 개입을 줄이기 위해서는 기존의 선박과 다른 개념과 기술을 개발하고 도입해야 한다. 수십 년 전 개발되어 해상 플랫폼 및 오프쇼어 분야에서 특정 용도로 사용되는 선박 시스템인 동적위치제어스템은 기존의 시스템에 더해 더욱 정교하고 섬세한 선박의 움직임이 가능하도록 다양한 기능을 제공한다. 최근의 영국에서 제출한 IMO 의제 문서에 의하면, 자율운항선박에는 전통적인 앵커와 같은 선박 설비에 더해 추가로 다른 기술이 적용될 수 있다고 밝히며, 동적위치제어시스템을 명시하였다. 본 논문에서는 이러한 기능 중 자율운항선박의 안전한 운항을 달성하기 위해 동적위치제어시스템에서 적용할 수 있는 요인을 알아보고 제시하고자 한다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.7 no.4
• /
• pp.833-838
• /
• 2003

This paper presents novel methods of recognizing license plates of passing vehicles outdo(n. In particular, the proposed method is much robust for inclined plates caused by the changes of camera placement. To acquire fine images of quickly passing vehicles under a wide range of illumination conditions, we developed a sensing system having superb characteristics. We expanded the dynamic range and eliminated the blurring of images of fast moving vehicles by synthesizing a pair of synchronized images with different intensities. furthermore, to extend the flexibility of the positioning of the TV camera, we propose a recognition algorithm that can be applied to inclined plates. The performance of the integrated system was investigated on real images of vehicles captured under various illumination conditions. The recognition rates of over 99% (conventional plates) and over 97% (highly inclined plates) shows that the developed system is effective for license plate recognition.

• Journal of Ocean Engineering and Technology
• /
• v.32 no.1
• /
• pp.43-50
• /
• 2018

Recently, various efforts have been made to develop oil and gas in the Arctic Ocean. It is very important to consider the load caused by ice in designing floating structures in the area. The magnitude of the ice load and its impact on a structure should be considered. In this paper, we analyze ice parameters affecting the DP performance of FPSO with a DP-assisted mooring system. Several ice characteristics are selected, and the resulting ice load is calculated using GEM software. Numerous simulations are conducted while changing the values of the parameters, and DP capability plots are generated to visualize the effects of changing these parameters. It is shown that the ice drift speed and thickness are the major properties to be considered in DP system design. The limitations of the analysis and future work are discussed in the conclusion.

• Journal of Power Electronics
• /
• v.18 no.1
• /
• pp.92-102
• /
• 2018

A sliding mode control (SMC) for servo motors based on the differential evolution (DE) algorithm, called DE-SMC, is proposed in this study. The parameters of SMC should be designed exactly to improve the robustness, realize the precision positioning, and reduce the steady-state speed error of the servo drive. The main parameters of SMC are optimized using the DE algorithm according to the speed feedback information of the servo motor. The most significant influence factor of the DE algorithm is optimization iteration. A suitable iteration can be achieved by the tested optimization process profile of the main parameters of SMC. Once the parameters of SMC are optimized under a convergent iteration, the system realizes the given performance indices within the shortest time. The experiment indicates that the robustness of the system is improved, and the dynamic and steady performance achieves the given performance indices under a convergent iteration when motor parameters mismatch and load disturbance is added. Moreover, the suitable iteration effectively mitigates the low-speed crawling phenomenon in the system. The correctness and effectiveness of DE-SMC are verified through the experiment.

• Journal of Advanced Information Technology and Convergence
• /
• v.8 no.2
• /
• pp.101-110
• /
• 2018

This paper introduces feedback linearization (FL) based adaptive sliding mode control (ASMC) effective against ground effects of the quadrotor UAV. The proposed control has the capability of estimation and effective rejection of those effects by adaptive mechanism, which resulting stable attitude and positioning of the quadrotor. As output variables of quadrotor, x-y-z position and yaw angle are chosen. Dynamic extension of the quadrotor dynamics is obtained for terms of roll and pitch control input to be appeared explicitly in x-y-z dynamics, and then linear feedback control including a ground effect is designed. A sliding mode control (SMC) is designed with a class of FL including higher derivative terms, sliding surfaces for which is designed as a class of integral type of resulting closed loop dynamics. The asymptotic stability of the overall system was assured, based on Lyapunov stability methods. It was evaluated through some simulation that attitude control capability is stable under excessive estimation error for unknown ground effect and initial attitude of roll, pitch, and yaw angle of $30^{\circ}$ in all. Effectiveness of the proposed method was shown for quadrotor system with ground effects.