• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.8
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• pp.1444-1448
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• 2010

The ball and beam system is one of the most popular models for studying control systems because of its nonlinearity and several control techniques have been proposed. Sliding mode control is a popular robust control method which rejects the external disturbance. In this paper, we propose a robust controller using the ${\epsilon}$-sliding surface. On the ${\epsilon}$-sliding surface, the system robustness and convergence can be manipulated via a use of ${\epsilon}$. We show the stability analysis and convergence analysis on the ${\epsilon}$-sliding surface. In addition, the experimental results show the validity of the proposed controller.

• Journal of KSNVE
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• v.5 no.4
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• pp.537-542
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• 1995

In this paper the method of modeling and optimization for the joint of the vehicle structure is proposed. First it is described that the method of substituting equivalent beam elements to spring elements for the joint. The stiffnesses of the spring elementsare calculated using the section properties of equivalent beam elements. To get required dynamic characteristics section properties of equivalent beam element are set to design variables and optimized. The study shows that joint stiffnesses can be effectively determined in designing vehicle structure.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.204-205
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• 2017

항로표지는 선박의 안전과 운항능률의 증진에 필수적인 수단으로 해상교통에 필수적이다. 등명기는 육상 및 해상에서 광파표지로 다양하게 활용되고 있으며 최근들어 장수명 및 저전력 소비의 장점을 갖춘 LED 광원의 적용이 확산되고 있다. 본 연구는 다중 배광 및 픽셀라이팅 기술 구현을 통해 등부표의 회전 운동에도 수평빔 유지제어가 가능한 신형 LED 등명기를 개발하여 암전 영역 제거 및 등질 인지향상을 통해 해양 사고 방지 및 해양 안전 향상을 목표로 한다. 등부표용 신형 LED 등명기 개발을 위해 다중 렌즈 및 픽셀 라이팅과 같은 광원/광학 기술과 제어 구동 시스템 설계 기술의 적용하였다. 본 연구에서 개발한 신형 LED 등명기는 등부표에 최적화된 수평배광 유지가 가능한 세계 최초의 등명기 시스템으로 국제 표준 제안 등을 통해 향후 세계 시장 진출을 추진하고자 한다.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2998-3000
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• 2005

The orthogonal frequency-division multiplexing (OFDM) technique is well known to be robust against the frequency-selective fading in wireless channels. It is due to the exploitation of a guard interval that is inserted at beginning of each OFDM symbol. Based or the conventional OFDM and a polyphase filtered orthogonal frequency division multiplexing (PF-OFDM) technique, we developed an adaptive beamforming algorithm for antenna arrays. The proposed algorithm would lead to an efficient use of channel, since it is possible to eliminate a guard interval and also easily suppress interchannel interference at the same time. In this paper, a series of computer simulations have been provided to show the performance of the proposed system.

• Journal of the Korean Vacuum Society
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• v.8 no.4B
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• pp.548-555
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• 1999

The NBI (Neutral BGeam Injection) System for the Korea Superconducting Tokamak Advanced Research (KSTAR) is composed of ion sources, neutralizers, bending magnets, ion dumps, and calorimeter. The vacuum chamber, in which all of the beam line components are enclosed, is composed of differential pumping system for the effective transfer of the neutral beams. The needed pumping speeds of each of the divided vacuum chamber and the optimized gas flow rate ot the neutralizer were calculated with the help of the particle balance equations. The minimum gas flow rate to the ion sources for producing needed beam current (120kV, 65A, 78MW), the pressure distributions in the vacuum chamber for minimizing re-ionization loss, and the beam loss rate on the beam line components were used as the input in the calculation. Also the scenario for short pulse operation was determined by analysing the time dependent equations. It showed that beam extraction during less than 0.5 sec could be made only with TMP.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.897-900
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• 1998

Through fuzzy logic controller is very useful to many areas, it is difficult to build up the rule-base by experience and trial-error. So, effective self-tuning fuzzy controller for the position control of ball and beam is designed. In this paper, we developed the neural network control system with fuzzy-neuron which conducts the adjustment process for the parameters to satisfy have nonlinear property of the ball and beam system. The proposed algorithm is based on a fuzzy logic control system using a neural network learinign algorithm which is a back-propagation algorithm. This system learn membership functions with input variables. The purpose of the design is to control the position of the ball along the track by manipulating the angualr position of the serve. As a result, it is concluded that the neural network control system with fuzzy-neuron is more effective than the conventional fuzzy system.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1986.10a
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• pp.40-44
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• 1986

The cassegrain antenna, 32metor , diameter, is designed for the satellite earth station at Boun. It is fed by a beam waveguide of type. The results of measurements G/T (Gain to Noise Temperature ratio) is 40.86dB/K at the elevation elevation angle 5˚ for 4GHz. And the average transmit and receive gain are 64.62dB and 61.3dB, respectively. They satisfy the values designed for the antenna. The sidelobe levels of the pattern also are in good accord with the recommendation of C.C.I.R.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.10
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• pp.581-586
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• 2005

The multi-beam side scan sonar system uses the towfish installed sonars, it is an equipment that search images of the bottom surface of the sea in real time. It is a typical equipment that is related to a sea investigation such as a geological survey, seabed communication cable and power line cable placing repair investigation, fish breeding ground investigation, sea purification, relic and mineral investigation, and mine and submarine search. Recently, it is used to sea purification and geological survey that require information of the correct surface of the seabed. Therefore, this research develops multi-beam sensors for a side scan sonar that supply various information with the fast scan speed and correct high resolution that is not a simple underwater investigation equipment.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.293-296
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• 2002

In this paper, we proposed a beam tilting microstrip patch array antenna for the reception of satellite signals by using low cost copper etched polyester films and foams. The configuration and coupling mechanism of the proposed antenna are similar to the dipole Yagi-Uda antenna. It is composed of 3 layers of polyester films and three layers of foam. In order to prevent unwanted radiation and coupling loss by microstrip feeding networks and parasitic patches, a stacked layer with rectangular slots above the driver patch array is inserted. The 16${\times}$8 element microstrip Patch way antenna is Presented by experimental results. Its beam patterns are affected by many parameters such as sizes of the patches, gap between the patches. characteristics of the substrates, feeding method, etc. Owing to its complexities of various design parameters, both simulation and experiment were performed. The fabricated antenna received DBS signal from KOREASAT 3 by doing nothing but adjusting azimuth direction.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.118-122
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• 2002

This paper is concerned with the design of the beam forming module that is a key unit of the active phased array antenna(APAA) system for mobile satellite communications. This module includes two blocks for main signal and tracking signal. Main signal block has the role of transmitting input signal from phased away antenna to tracking signal block. And, tracking signal block executes main roles, beam forming of tracking signal and electronic beam control. The several electrical performances of this module, phase characteristics and linear gain, etc., agreed with specifications needed for APAA, and for more clear verification of the performances, the satellite communication test of the APAA including the modules was accomplished in the outdoors.