• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.152-152
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• 2000

Abeles가 특성 행렬을 이용하여 기본 이론을 확립한 이래, 광학 박막의 설계는 개인용 컴퓨터의 출현으로 다양한 방법으로 쉽게 할 수 있으며, 그 응용이 빠르게 증가하고 있다. 또한 이온빔을 이용한 증착 기술의 발전으로 덩어리에 가까운 박막을 증착하고 있으며 박막의 광학적, 기계적 특성을 향상시키고 있다. 최근에는 초고속 다용량 광정보통신, 디스플레이, 레이저, 광센서, 광자기술, 광전자 등의 발전에 따라 고품질의 박막을 제작하기 위한 기술이 발전하고 있으며, 이에 따라 합성 설계 방법과 물질의 기본적 특성을 분석하기 위한 방법도 다양하게 발전되고 있다. (중략)

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.1561-1564
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• 2004

초고속 유무선 통신망이 확대됨에 따라 디지털 데이터 통신 및 저장 시스템 설계 시 통신채널에서 발생하는 오류를 효율적으로 제어하기 위한 오류정정부호 장치가 중요한 요소가 되었다. 본 논문에서는 기존의 셀룰라 오타마타 기반의 오류정정부호를 개선시킨 이중 오류정정부부호를 설계하는 방법을 제안한다.

• The Journal of the Acoustical Society of Korea
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• v.39 no.5
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• pp.490-496
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• 2020

We present a method to improve the performance of the multi-channel Wiener filter in noisy environment. To build subspace-based multi-channel Wiener filter, in the case of single target source, the target speech component can be effectively estimated in the principal subspace of speech correlation matrix. The speech correlation matrix can be estimated by subtracting noise correlation matrix from signal correlation matrix based on the assumption that the cross-correlation between speech and interfering noise is negligible compared with speech correlation. However, this assumption is not valid in the presence of strong interfering noise and significant error can be induced in the principal subspace accordingly. In this paper, we propose to adjust the principal subspace vector using speech presence probability and the steering vector for the desired speech source. The multi-channel speech presence probability is derived in the principal subspace and applied to adjust the principal subspace vector. Simulation results show that the proposed method improves the performance of multi-channel Wiener filter in noisy environment.

• The Journal of the Acoustical Society of Korea
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• v.43 no.4
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• pp.369-382
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• 2024

To suppress the reverberation in the active sonar system, the non-negative matrix factorization-based reverberation suppression methods have been researched recently. An estimation loss function, which makes the multiplication of basis matrices same as the input signals, has to be considered to design the non-negative matrix factorization methods, but the conventional method simply chooses the Kullback-Leibler divergence asthe lossfunction without any considerations. In this paper, we examined that the Kullback-Leibler divergence is the best lossfunction or there isthe other loss function enhancing the performance. First, we derived a modified reverberation suppression algorithm using the generalized beta-divergence function, which includes the Kullback-Leibler divergence. Then, we performed Monte-Carlo simulations using synthesized reverberation for the modified reverberation suppression method. The results showed that the Kullback-Leibler divergence function (β = 1) has good performances in the high signal-to-reverberation environments, but the intermediate function (β = 1.25) between Kullback-Leibler divergence and Euclidean distance has better performance in the low signal-to-reverberation environments.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.3
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• pp.285-290
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• 2007

In this paper, we presents robust digital redesign (DR) method for observer-based linear time-invariant (LTI) system. The term of DR involves converting an analog controller into an equivalent digital one by considering two condition: state-matching and stability. The design problems viewed as a convex optimization problem that we minimize the error of the norm bounds between interpolated linear operators to be matched. Also, by using the bilinear and inverse bilinear approximation method, we analyzed the uncertain parts of given observer-based system more precisely, When a sampling period is sufficiently small, the conversion of a analog structured uncertain system to an equivalent discrete-time system have proper reason. Sufficiently conditions for the state-matching of the digitally controlled system are formulated in terms of linear matrix inequalities (LMIs).

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.1 s.71
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• pp.63-71
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• 2006

This study presents the effective stiffness-based optimal technique to control Quantitatively lateral drift for shear wall-frame structure system using sensitivity analysis. To this end, the element stiffness matrices are constituted to solve the compatibility problem of displacement degree of freedom between the frame and shear wall. Also, lateral drift constraint to introduce the approximation concept that can preserve the generality of the mathematical programming and can effectively solve the large scaled problems is established. And, the section property relationships for shear wall and frame members are considered in order to reduce the number of design variables and differentiate easily the stiffness matrices. Specifically, constant-shape assumption which is uniformly varying in size during optimal process is applied in frame structure. The thickness or length of shear wall can be changed depending on user's intent. Two types of 20 story shear wall-frame structure system are presented to illustrate the features of the stiffness-based optimal design technique.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.6
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• pp.700-705
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• 2012

This paper addresses an intelligent digital redesign (IDR) technique for observer-based output-feedback control systems, in order to efficiently convert a pre-designed Takagi-Sugeno fuzzy model-based analog controller into a sampled-data one in the sense of state matching. A delta operator is used to get an asymptotic relation between the analog and the sampled-data control systems. The IDR problem is viewed as a minimization problem of the norm distances between linear operator to be matched. The condition is represented as linear matrix inequalities, and the separation principle on the IDR is shown.

• Journal of Navigation and Port Research
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• v.38 no.1
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• pp.29-37
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• 2014

In this paper, the author consider control system design problem of the surface vessel where any types of floating units are included. To keep their motion/position, the Dynamic Positioning System(DPS) is equipped in. Even though sometimes the thrust systems are installed on them, in general the mooring winch system with the rope/wire is used. Therefore, in this paper we consider a single type mooring winch control problem to keep the vessel's position. For this, we introduce an easy and useful control approach which is based on LQ control theory. In this approach, we introduce the frequency dependent weighting matrices which give the system filters to shape frequency characteristics of the controlled system and guarantee the control performance. Based on this, we will show that the proposed approach works well.

• Journal of Advanced Navigation Technology
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• v.15 no.2
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• pp.213-220
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• 2011

In this paper, the channel preprocessor with an area-efficient architecture is proposed for the MIMO symbol detector which can support four transmit and receive antennas. The proposed channel preprocessor can shrink the channel dimension to reduce the hardware complexity of the MIMO symbol detector. Also, the proposed channel preprocessor is implemented with very low complexity by using QR decomposition (QRD) and log-number system (LNS). By applying QRD and LNS to the nulling matrix calculation block, the numbers of matrix-multiplications and matrix-divisions are decreased and thus the complexity of the proposed channel preprocessor is significantly reduced. The proposed channel preprocessor was designed in a hardware description language (HDL) and synthesized to gate-level circuits using 0.13um CMOS standard cell library. With the proposed channel preprocessor, the number of logic gates for channel preprocessor is reduced by 20.2% compared with the conventional architecture.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.3A
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• pp.151-156
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• 2012

In this paper, design of quasi-cyclic(QC) low-density parity-check codes is proposed to have full diversity for space-time bit-interleaved coded modulation(ST-BICM) systems. Necessary and sufficient conditions that the proposed scheme has full diversity are proved as the condition that submatrices corresponding to the system part of codewords are invertible. And new construction method of binary invertible matrices for QC LDPC codes in ST-BICM systems are also proposed and modification for parity-check matrices are also explained.