• Journal of the Korean Institute of Telematics and Electronics B
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• v.29B no.3
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• pp.6-15
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• 1992

This paper proposes a method for the global optimization of redundancy over the whole task period for a kinematically redundant robot. The necessary conditions based on the calculus of variations for an integral type cost criterion result in a second-order differential equation. For a cyclic task, the periodic boundary conditions due to conservativity requirements are discussed. We refine the two-point boundary value problem to an initial value adjustment problem and suggest a numerical search method for providing the conservative global optimal solution using the gradient projection method. Since the initial joint velocity is parameterized with the number of the redundancy, we only search the parameter value in the space of as many dimensions as the number of degrees of redundancy. We show through numerical examples that multiple nonhomotopic extremal solutions and the generality of the proposed method by considering the dynamics of a robot.

• Proceedings of the Korean Society of Computer Information Conference
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• 2012.07a
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• pp.243-246
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• 2012

A new multi inner stage(MIS) cyclone was designed to remove the acidic gas and minute particles of harmful materials produced from electronic industry. To characterize gas flow in MIS cyclone, pressure and velocity distribution were calculated by means of computational fluid dynamics(CFD) commercial program. Also, the flow locus of particles and particle removal efficiency were analyzed by Lagrangian method. When outlet pressure condition was -1,000 Pa, the efficiency was the best in this study. Based on the CFD simulation result, the pressure loss and destruction removal efficiency was measured through MIS cyclone experiment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.3
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• pp.213-220
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• 1990

DC servo motor has been often used as the position control system, because the performance is excellent on the velocity and position control system. When the unknow disturbance and accessible load torque are imposed on the position control of DC servo motor, this system has the steady and/or transient state error. In this paper, a new method which has high stiffness for reducing the error is proposed. This error will be reduced by acceleration control. The effectiveness of the acceleration control is confirmed by using computer simulation.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.224-228
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• 2002

To study the trafficability on soft and cohesive benthic terrain, a soil bin is designed and constructed. The information of shear strength of pacific seafloor and the results of dimensional analysis of vehicle-train system are used as basic datum for concept design of soil bin. Cohesive benthic terrain is modeled by means of bentonite-water mixture. The shear strength of the mixture is measured by motorized shear meter. Several facilities are constructed for mixing and evening modeled soil, transporting vehicle model. The shear strength in soil bin is investigated for depth, age and velocity. The result of this study is used as basic information to the experiment, study for development of crawler on benthic terrain.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.67-72
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• 2006

Questionnaire survey on performance requirement of ship’s speed such as not only accuracy but also response and robustness were carried out, and the experiments to survey the GPS performances of static and dynamic characteristics were carried out simultaneously. In this paper, the questionnaire survey focusing on docking maneuvering, some analytic results of the survey, the results of GPS performance, and the possibility of adaptation for docking maneuvering on SDME and GPS are discussed. Consequently, from the results of questionnaire survey the performance requirement of ship’s speed in docking/anchoring maneuvering have need under 1cm/sec on the standard deviation, and speed information from GPS was adopted to use maneuvering information in docking/anchoring.

• Journal of information and communication convergence engineering
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• v.11 no.3
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• pp.199-206
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• 2013

An emergency monitoring system for the elderly, which uses acceleration data measured with an accelerometer, angular velocity data measured with a gyroscope, and heart rate measured with an electrocardiogram, is proposed. The proposed fall detection algorithm uses multiple parameter combinations in which all parameters, calculated using tri-axial accelerations and bi-axial angular velocities, are above a certain threshold within a time period. Further, we propose an emergency detection algorithm that monitors the movements of the fallen elderly person, after a fall is detected. The results show that the proposed algorithms can distinguish various types of falls from activities of daily living with 100% sensitivity and 98.75% specificity. In addition, when falls are detected, the emergency detection rate is 100%. This suggests that the presented fall and emergency detection method provides an effective automatic fall detection and emergency alarm system. The proposed algorithms are simple enough to be implemented into an embedded system such as 8051-based microcontroller with 128 kbyte ROM.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.6A
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• pp.825-832
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• 2000

광섬유 통신 시스템이 고속화되고 장거리를 전송하게 될 수록 편광모드 분산의 중요성은 더욱 부각되어 있다. 따라서 본 논문에서는 복굴절 광섬유에서 비선형 광펄스의 전파특성을 편광 모드 분산의 영향을 고려하여 시뮬레이션하였으며 이러한 현상이 발생되는 것을 알 수 있었다. 그리고 광섬유 비션형성에 의해서 GVD(Group Velocity Dispersion)와 마찬가기로 PMD(Polarization Mode Dispersion)에서도 부분적인 보상 현상이 나타남을 수치 결과를 통해 알 수 있었다. 이러한 광 전송 시뮬레이션을 구현하기 위해서 기존의 단계분할 푸리에 방식 (SS-FM, Split-Step Fourier Method)보다 장거리 전송시 오차의 발생이 적은 단계 분할 유한 요소법)SS-FEM, Split-Step Finite Element Method)을 적용하였으며, 또한 그 단점인 수행 속도를 개선한 희귀 행렬 근사 단계 분할 유한 요소법을 제안하였다. 그 결과 제안된 방법이 기존의 푸리에 연산법이나 일반적인 유한 요소법과 비교하여 더 빠른 수행 속도를 나타내는 것을 알 수 있었다.

• Journal of information and communication convergence engineering
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• v.3 no.1
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• pp.43-48
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• 2005

In this paper, the adaptive fuzzy logic controller(AFLC) is proposed, which uses real-coding genetic algorithm showing a good performance on convergence velocity and diversity of population among evolutionary computations. The effectiveness of the proposed AFLC was demonstrated by computer simulation for speed control system of AC servo motor. As a result of simulation for the AC servo motor, it is shown the proposed AFLC has the better performance on overshoot, settling time and rising time than the PI controller which is used when tuning AFLC.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.1973-1977
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• 2006

This paper reports the absolute position tracking algorithm of underwater vehicles such as ROV, AUV in global region by fusing sensor informations of IMU, DVL, USBL, DGPS etc. This algorithm is to be used in the position tracking of the 6,000m class deep-sea unmanned underwater vehicle, HEMIRE for scientific exploration.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.975-978
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• 2010

This paper presents a Kalman filter based modeling algorithm for autonomous robots. State of the robot systems is measured by using embedded sensors and then carried to a host computer via ubiquitous sensor network (USN). We settle a linear state space motion equation for unknown system dynamics and modify a popular Kalman filter algorithm in deriving suitable parameter estimation mechanism. We conduct real-time experiment to test our proposed modeling algorithm where velocity state of the constructed robot is used as system observation.