• Proceedings of KOSOMES biannual meeting
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• 2007.05a
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• pp.169-174
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• 2007

The purpose in having a control rod an a buoy system is to control the motion of it. The system may be composed entirely af a single circular cylinder finder and a lang mooring anchor cable. A control rod has one function to perform in meeting its purpose, and that is to develop a control force in consequence of its orientation and movement relative to the water. The forces and moments generated as a result of the effects of mutual interference, then determine the stability characteristics of the body. In this paper, the study of control-rod-attached buoy's 2-dimensional section was accomplished. model tests and numerical simulations had been carried out with different diameters of control rods. and varying the Reynolds number $Re=5,000{\sim}25,000$ based an the cylinder diameter(D=50mm) to. predict the performance af the body and the 2 frame particle tracking method had been used to obtain the velocity distribution in the flaw field 50mm circular cylinder had been used during the whale experiments and measured results had been compared with each other.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.148-152
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• 1992

수치제어(NC: numerical control) 기술은 공장자동화를 위한 중요기술이다. 우리산업현장에 공장 자동화가 확장되면 서 NC 공작기계산업용 로봇, 삼차원 좌표측정기 등의 사용이 매우 증가되고있다. 이러ㅗ한 수치제어용 기계에서는 자동 위치제어를 위하여 길이변위와 회전각도감지용센서인 NC 엔코더가 매우 중요한 부품이다. NC 엔코더에는 선형 엔코더( NC-스케일)와 회전 엔코더가 있으며, 각각 직선운동과 회전운동을 제어하기위해서 필요한 자동화 부품이다. 선형 엔코 더는 직선운동의 변위를 감지하며 NC-스케일 이라고도 말한다. 우리 나라에서는 아직 엔코더 제작기술을 개발하지 못하여 전량수입에의존하고 있다. 이러한 NC 엔코더의 수요는 해외시장뿐만 아니라 국내시장에서도 급격히 증가 되고있으며 국산화 개발이 시급하다. 이 글에서는 NC-스케일 제조기술을 개발함에있어서 연구하였던 참조위치 마크(Rrference Mark)설계 기술을 정리한다.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.5
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• pp.37-43
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• 2002

In this paper, an integrated optimum design method for hybrid structural control system is studied. Not only the distribution and the capacity of passive devices but also those of active devices, and the controllers are treated as design variables in the proposed approach. Multi-objective optimization problem is formulated by using the preference function, which is newly defined in this study. Genetic algorithm is adopted as a numerical searching technique in order to simultaneously find the optimum solutions. The validity of the proposed method is verified through the example designs and the numerical simulations of an earthquake excited multi-degrees-of-freedom structure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.9
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• pp.2027-2034
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• 1997

Frame relay is a fast packet switching technology that performs relaying and multiplexing frames with variable lengths over a wide area link at the T1 or E1 speed, by elminating error and flow control in the network. In frame relay networks, congestion control is typically performed through the rate enforcement with a discard eligibility (DE) bit, and the explicit negative feedback meachanisms using explicit congetion notification bits. In this paper, we consider the congestiong control scheme using the rate enforcement mechanism with DE bit for frame relay network. Assuming that each frame with exponentially distributed length arrives according to the Poission fashion, we can treat the frame relay switch as an M/M/1/K priority queueing system with pushout basis. We analyze and present the blocking probabilities and waiting time distributions of frames.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.127-132
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• 2001

자기유변유체감쇠기를 이용한 반능동 제어 시스템은 최근에 개발되어 승용차의 승차감 향상을 위한 진동제어에 사용되고 있다. 본 연구에서는 바람, 지진, 파랑 등에 대한 대형구조물의 진동제어를 위한 MR 감쇠기의 적용성을 분석하기 위하여, 미국 토목학회에서 제안한 76층 건물의 풍하중에 대한 진동제어에 관한 Benchmark Problem에 대하여 수치모의 해석을 수행하였다. 연구결과로부터, 풍하중에 대한 고층 건물의 진동제어를 위하여 MR 감쇠기를 이용한 반능동 제어의 성능은 능동형 동조질량 감쇠기의 성능과 유사함을 확인할 수 있었다.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2043-2045
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• 2003

본 연구에서는 자기부상 방식의 스테이지 시스템 설계 및 제작을 행하고 시스템의 제어성능평가를 하고자 한다. 본 논문에서는 제어성능의 효율성을 향상시키기 위하여 부상체(Platen)의 기계적인 모델링을 행하고 Platen의 PTP(point to point) 및 궤도추종제어가 가능한 슬라이딩 모드제어기를 제안하였다. 제안한 슬라이딩 모드제어기는 모델링 오차 및 외란에 대해서도 강인한 제어성능을 얻을 수 있으며 수치시뮬레이션을 통하여 그 유용성을 확인하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.9
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• pp.12-26
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• 2004

A new treatment of cell-interface flux in AUSM-type methods is introduced to reduce the numerical dissipation. Through analysis of TVD limiters, a criterion for the more accurate prediction of cell-interface state is found out and M-AUSMPW+ is developed by determining the transferred property newly and appropriately within the criterion. The superiority of M-AUSMPW+ is clearly revealed in multi-dimensional flow problems. It can eliminate numerical dissipation effectively in a non-flow aligned grid system. As a result, M-AUSMPW+ is shown to be much more accurate and effective than other previous schemes in multi-dimensional problems. Through a stationary contact discontinuity, a vortex flow, a shock wave/boundary layer interactions and viscous shock tube problems, it is verified that accuracy of M-AUSMPW+ is improved.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.4
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• pp.203-214
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• 2010

This study numerically investigates the wave control of 2-rowed Impermeable Rectangular Submerged Dike(IRSD) with an object of how to control short-period and solitary waves simultaneously based on the Bragg resonance phenomenon that elevates the wave control performance. The boundary integral method using Green formula and the 3-D one-field Model for immiscible TWO-Phase flows (TWOPM-3D) by 3-D numerical wave flume have been used for the numerical predictions for short-period and solitary waves, respectively. These numerical models were verified through the comparisons with the previously published numerical results by other researchers. Through the parametric tests of numerical experiments for short-period waves, an optimum model of 2-rowed IRSD of a lowest transmission coefficient has been found. Furthermore, the performances of 3-D wave control for solitary waves were evaluated for the various free board, crown widths and gap distance between dikes, and have been compared with those of a single-rowed IRSD. Numerical results show that a 2-rowed IRSD with a less cross sectional area than 1-rowed one improves the wave attenuation performances when it is compared to that of single-rowed IRSD. Within the test frequency ranges of the numerical simulations conducted in this study, 2-rowed IRSD with an optimum gap distance shows an outstanding improvement of the wave attenuation up to 58% compared to that of single-rowed IRSD.

• JOURNAL OF ELECTRICAL WORLD
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• no.9 s.14
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• pp.21-25
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• 1977

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.1
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• pp.36-47
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• 2012

In this study, the control performance of resonator was reviewed through numerical analysis and 3-dimensional hydraulic model experiments by attaching the resonator suggested in the existing studies to the openings of rectangular harbor and breakwater placed in a straight line to reduce short-period waves. In the numerical analysis, linear analysis method of singularity distribution method based on vertical-line Green function and full non-linear analysis method by 3D-NIT model were applied, and the validity of the numerical analysis methods was verified through comparative analysis between results of hydraulic experiments and numerical analysis results. In addition, effectiveness of the resonator was confirmed by reviewing its control performance on the short-period waves through review on the comparison with the case in which the resonator is not attached.