• 제어로봇시스템학회:학술대회논문집
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• 1988.10b
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• pp.753-758
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• 1988

In this paper, we propose a new method of designing a reduced-order controller for a linear discrete-time system. Firstly, we study a design problem for a two-degree-of-freedom control system with a feedforward controller. Secondly, in order to obtain a reduced-order controller, frequency-weighted least squares approximation problems are considered. Thirdly, we propose a synthesis procedure of a reduced-order controller. Finally, an example is given to illustrate the effectiveness of this proposed method.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.1117-1120
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• 1999

In this paper, we design the H$\infty$ optimal controller satisfying robust stability and performance in spite of the plant uncertainty for an electro-mechanical actuator system and analyze the controller in frequency domain. H$\infty$ optimal controller K was designed using iteration algorithm suggested by DOYLE. Using the controller in an electro-mechanical actuator system, the joint with very small coupling rigidity coefficient was used to vary the control parameter. The plant unstructured uncertainty was assumed to be a multiplicative type.

• Journal of the Korean Ceramic Society
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• v.33 no.9
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• pp.1019-1023
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• 1996

The dielectric properties at microwave frequencies of B site complex perovskite La(Zn1/2Ti1/2)O3 which has +3 ion in A site were investigated. maximum Q*F value of the specimens was 59000 dielectric constant 34, temperature coefficient of resonant frequency -52 ppm/$^{\circ}C$. XRD pattern of the sintered specimen shows (111) ssuperlattice reflection which indicates Zn and Ti cation ordering.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.571-574
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• 2000

A complex coefficient filter obtained by directly exchanging several reactance elements included in a real coefficient, filter for imaginary valued resistors is described. By using the proposed method, four varieties of complex coefficient filter are obtained. The stability problem is described. Finally, the frequency responses of the proposed kiters are shown.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.546-546
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• 2006

• Korean journal of applied entomology
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• v.51 no.3
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• pp.255-263
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• 2012

High frequency sounds disrupt physiological processes, such as feeding behavior, development and immune responses of Spodoptera exigua. We analyzed high frequency sounds with respect to biochemical changes in S. exigua. High frequency sound (5,000 Hz, 95 dB) suppressed protein synthesis and secretion of midgut epithelium. It also significantly inhibited a digestive enzyme activity of phospholipase $A_2$. The gene expression of three different heat shock proteins and apolipophorin III was altered, particularly in midgut tissue in response to high frequency sound treatments. High frequency sound treatments significantly increased sugar and lipid levels in hemolymph plasma. These results suggest that high frequency sounds are a physiological stress that induces biochemical changes in S. exigua.

• Journal of information and communication convergence engineering
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• v.9 no.6
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• pp.689-694
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• 2011

Cellular automata are discrete dynamical systems, which provide the basis for the synthesis of complex emergent behavior. This paper proposes a new algorithm of digital watermarking based on cellular automata transform (CAT). The idea of two-dimensional CAT is introduced into the algorithm. After the original image is disassembled with 2D CAT, the watermark information is embedded into the Middle-frequency of the carrier picture. Cellular automata have a huge number of combinations, such as gateway values, rule numbers, initial configuration, boundary condition, etc. Using CAT, the robustness of the watermark will be tremendous strengthened as well as its imperceptibility. Experimental results show that this algorithm can resist some usual attacks such as compression, sharpening and so on. The proposed method is robust to different attacks and is more security.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2625-2628
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• 2003

Phase locked loops are widely used in many applications such as frequency synthesis, clock/data recovery and clock generation. In nearly all the PLL applications, low jitter and fast locking time is required. Without using adaptive loop filter, this paper proposes very simple method for improving locking time and jitter reduction simultaneously in charge pump PLL(CPPLL) using Daul Phase/Frequency Detector(Dual PFD). Based on the proposed scheme, the lock time is improved by 23.1％, and the jitter is reduced by 45.2％ compared with typical CPPLL.

• Journal of The Korean Astronomical Society
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• v.36 no.spc1
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• pp.135-143
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• 2003

Solar radio astronomy is about to undergo a revolution with the advent of a new radio synthesis array, the Frequency Agile Solar Radiotelescope (FASR). The array will consist of more than 100 antennas (5000 baselines), and will be designed to meet the special challenges of solar imaging. It will produce high-quality images at hundreds of frequencies in the range 20 MHz-24 GHz. We briefly describe the plans for the instrument, and then concentrate on the range of science that is expected to be addressed, using current state-of-the-art solar radio observations and modeling to illustrate FASR performance. We end with an assessment of the current status of the instrument, and plans for future.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.168-175
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• 2010

The issue of rejecting periodic disturbances arises in various applications dealing with rotating machinery. A new method using DIDF (Dual-Input Describing Function) is presented for the rejection of periodic disturbances with uncertain frequency. This can be added to an existing feedback control system without altering the closed-loop system stability. The objective is to design a nonlinear compensator to secure specified oscillation amplitude and frequency which are the same as disturbances. We suggest two procedures to determine coefficients for DIDF's synthesis. The structure of the proposed DIDF is so simple that we can easily synthesize. A number of computer simulations were carried out to demonstrate the salient feature of the proposed DIDF compared to the conventional ones(that is, adaptive algorithms).