• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.6
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• pp.450-456
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• 2000

In this paper, we proposed a novel control method which uses the internal impedance angles as a control parameter to drive traveling wave type ultrasonic motor. An impedance characteristic of the ultrasonic motor is obtained by analysis of the equivalent circuits including the external inductor used to generate the coupled resonance. The phase angle of internal impedance to achieve optimal control performance is derived. For the tracking of impedance angle, an information of phase difference is obtained from the applied voltage and current. The high speed phase difference detector is designed to monitor the phases of ultrasonic motor. The effectiveness of the proposed control scheme is clarified by experiments.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.277-284
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• 2003

To meet demand for large-scale new personnel caused by active railway investment projects such as high-speed line construction, electrification and double-tracking of the existing lines, we KNR need to establish a subsidiary firm for each field instead of personnel augmentation. The establishment of subsidiaries is expected to solve the problem of the current outsourcing services, reduce costs and in the long term, improve the efficiency of railway business. In addition, we also suggest, as a pilot project, setting up Korean Freight Inspection Company in charge of conducting light and heavy maintenance for freight cars.

• Journal of Integrative Natural Science
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• v.12 no.4
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• pp.105-115
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• 2019

In this paper, a prediction system is proposed to control the brightness of smart street lamps by predicting the moving path through the reduction of consumption power and information of pedestrian's past moving direction while meeting the function of existing smart street lamps. The brightness of smart street lamps is adjusted by utilizing the walk tracking vector and soft hand-off characteristics obtained through the motion sensing sensor of smart street lamps. In addition, the motion vector is used to analyze and predict the pedestrian path, and the GPU is used for high-speed computation. Pedestrians were detected using adaptive Gaussian mixing, weighted difference imaging, and motion vectors, and motions of pedestrians were analyzed using the extracted motion vectors. The preprocessing process using linear interpolation is performed to improve the performance of the proposed prediction system. Fuzzy prediction system and neural network prediction system are designed in parallel to improve efficiency and rough set is used for error correction.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.77.2-77.2
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• 2014

Questions of how our Milky Way evolves through the interaction with its environment have been constantly raised. One particularly interesting question is how the metallicity would change as our Milky Way goes through collision with HVCs. Because of the possibility of HVCs providing fuel for star formation in the Galactic disk, we simulate the collision between HVCs and the Galactic disk. More specifically, we trace how the Galactic metallicity changes throughout the process of HVCs colliding with our Milky Way based upon a specific scenario that HVCs are primordial gas left-overs from an ancient galaxy formation. Such mixing between metal-rich gas (disk) and metal-poor HVC can be traced by running numerical simulations with the FLASH code due to its capability of tracking down the abundance change of a specific element such as carbon at each time step of the hydrodynamic evolution. As for now, we give how this mixing depends on model parameters that we choose such as collision speed, initial metallicities, temperature and so on.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1820-1828
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• 2001

The dynamics of the 6-3 Stewart platform manipulator (SPM) is newly derived based on the kinematic relations particularly developed fur the SPM. The essence of the analysis is to deal with three subsystems of the SPM, each consisting of the command and feedback line links associated with two joined neighboring actuators. The dynamics of the command and feedback line links are first formulated using Lagrange and Newton-Euler method and then combined to derive the dynamic equations of motion fur the SPM. The derived nonlinear equations of motion are so computationally effective that it can be easily applied to real-time high-speed tracking control of 6-3 SPM.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2017.11a
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• pp.164-165
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• 2017

본 논문에서는 고속의 이동체를 추적하기 위하여 적외선 스테레오 카메라 시스템을 이용하였다. 열원을 감지할 수 있는 적외선 카메라를 이용해 고온의 추진체를 찾는다, 그리고 고속 이동체의 3 차원 위치를 계산하기 위해 스테레오 카메라 시스템을 사용하여 카메라와 고속 이동체 사이의 거리를 계산하였다. 마지막으로 인공신경망을 이용한 회귀분석으로 고속 이동체의 궤적을 추정하였다. 제안한 시스템이 동작하는 것을 실험 결과를 통해 보인다.

• Proceedings of the KWS Conference
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• 2002.05a
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• pp.49-52
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• 2002

A vision sensor measure range data using laser light source, This sensor generally use patterned laser which shaped single line. But this vision sensor cannot satisfy new trend which needs faster and more precise processing. The sensor's sampling rate increases as reduced image processing time. However, the sampling rate can not over 30fps, because a camera has mechanical sampling limit. If we use multi line laser pattern, we will measure multi range data in one image. In the case of using same sampling rate camera, number of 2D range data profile in one second is directly proportional to laser line's number. For example, the vision sensor using 5 laser lines can sample 150 profiles per second in best condition.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.97-100
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• 2001

This paper introduces that it minimizes interference between links at high speed trajectory tracking of 2-degree parallel link robot. And in spite of system uncertainty, it introduces controller design method which is satisfied with performance specification. To do these, we separate two channels from parallel link robot through ICD(Individual Channel Design) and design controller of each channel using QFT(Quantitative Feedback Theory). Finally, we make sure of robustness and excellence of QFT control1er through simulation and experiment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.3
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• pp.617-626
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• 1999

For the purpose of high speed and reliable data transmission through the frequency response variation channel by load fluctuation, we present CSK signal transmission characteristics by computer simulation. Also using the simple structure of Roll-off filter at the CSK receiving system, the exact synchronization tracking and data detection without error at the worst case of S/I=2 and S/N=2 were achieved.

• 전기의세계
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• v.14 no.2
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• pp.14-24
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• 1965

The characteristics of servo-multipliers and its accuracies are analyzed. From the analysis a low cost high accuracy four quadrant servo-multiplier with first derivative output feedback is built. The multiplier servomechanism has a second order system response with a damping ratio of 0.8 and computing bandwidth of 4 cycles per second, and its tracking accuracy at low speed of 0.5 volt per second is 0.9 per cent of maximum output voltage and static accuracy is better than 0.6 per cent. Method of testing this multiplier and the results are also described. The test on the characteristics of the multiplier shows that the results agree with theoretical values satisfactorily, and justifies the use of the servo-multiplier for slow type analog computers.