• Current Optics and Photonics
• /
• 제1권2호
• /
• pp.157-162
• /
• 2017

In large liquid crystal displays, the image quality in an oblique viewing direction is a crucial issue. From this perspective, 8-domain polymer-stabilized vertical alignment (PS-VA) mode has been developed to suppress the color shift in oblique viewing directions, compared to that in 4-domain PS-VA mode. To realize the 8-domain PS-VA, the four domains in a pixel are each divided into two regions, such that applying different electric potentials result in different tilt angles in these two regions, while keeping four azimuthal directions in each domain. However, applying different voltages in a pixel causes drawbacks, such as requiring additional processes to construct a capacitor and a transistor, which will further reduce the aperture ratio. Here we propose a different approach to form the 8-domain, by controlling surface polar anchoring energy and the width of patterned electrodes in two regions of a pixel. As a result, the gamma-distortion index (GDI), measured at an azimuthal angle of $0^{\circ}$, is reduced by about 23% and 8%, compared to that of a conventional 4-domain at polar angles of $30^{\circ}$ and $60^{\circ}$ respectively.

• IEIE Transactions on Smart Processing and Computing
• /
• 제3권2호
• /
• pp.65-73
• /
• 2014

An overall responding security-centered framework is necessary required for infringement accidents, failures, and cyber threats. On the other hand, the correspondence structures of existing administrative, technical, physical security have weakness in a system responding to complex attacks because each step is performed independently. This study will recognize all internal and external users as a potentially threatening element. To perform connectivity analysis regarding an action, an intelligent convergence security framework and road map is suggested. A suggested convergence security framework was constructed to be independent of an automatic framework, such as the conventional single solution for the priority defense system of APT of the latest attack type, which makes continuous reputational attacks to achieve its goals. This study suggested the next generation convergence security framework to have preemptive responses, possibly against an APT attack, consisting of the following five hierarchical layers: domain security, domain connection, action visibility, action control, and convergence correspondence. In the domain, the connection layer suggests a security instruction and direction in the domains of administrative, physical and technical security. The domain security layer has consistency of status information among the security domain. A visibility layer of an intelligent attack action consists of data gathering, comparison and decision cycle. The action control layer is a layer that controls the visibility action. Finally, the convergence corresponding layer suggests a corresponding system of before and after an APT attack. The administrative security domain had a security design based on organization, rule, process, and paper information. The physical security domain is designed to separate into a control layer and facility according to the threats of the control impossible and control possible. Each domain action executes visible and control steps, and is designed to have flexibility regarding security environmental changes. In this study, the framework to address an APT attack and load map will be used as an infrastructure corresponding to the next generation security.

• 대한의용생체공학회:의공학회지
• /
• 제17권3호
• /
• pp.347-354
• /
• 1996

This paper presents digital hearing aids signal processing system in WT(wavelet transform) domain. For implementation of hearing aids in WT domain, the gain in frequency domain is approximated in WT domain. We also present the gain selection algorithm to deal with the change of input signal power. Most transform methods produce blocking effect, and this effect degrades the convergence rate of feedback canceller. As a solution, we proposed wavelet transform bascd feedback canceller. To evaluate the performance, we compared it with LOT (lapped orthogonal transform) method in the frequency domain. This system has not shown the blocking effect, and improves convergence rate as compared with the LOT based feedback canceller.

• 한국수학교육학회지시리즈B:순수및응용수학
• /
• 제15권1호
• /
• pp.47-55
• /
• 2008

Local convergence results for three Newton-like methods in Banach space are provided. A comparison is given between the three convergence radii. Then we show that using the largest convergence radius we can pick an initial guess from with we start the corresponding iteration. It turns out that after a finite number of steps we can always use the iterate found as the starting guess for a faster method, since this iterate will be inside the convergence domain of the new method.

• 융합신호처리학회논문지
• /
• 제9권4호
• /
• pp.295-303
• /
• 2008

변환영역 적응필터는 시간영역 적응필터보다 일반직으로 수렴속도가 빠르지만 필터의 차수가 증가함에 따라 계산량이 크게 증가한다. 이러한 문제점은 변환영역 적응필터를 서브밴드 분해구조로 변경함으로써 해결할 수 있다. 이 논문에서는 일반화된 서브밴드 분해 FIR 적응 필터의 수렴속도 향상을 위해 웨이블릿 변환영역에서 다이아딕 희소인자 서브필터를 가지는 일반화된 서브밴드 분해 FTR 적응 필터의 구조를 설계하였다. 그리고 이 적응필터에서 변환영역의 일반화된 등가입력을 유도하고 이 입력을 이용하여 LMS 일고리듬에 대한 수렴특성을 해석 및 평가하였다. 이 서브밴드 FIR 적응필터를 이용하여 역 모델링 시스템과 주기성 잡음제거기를 구성하고 LMS 알고리듬 대한 이 시스템들의 수련속도를 이산푸리에 변환을 이용한 서브밴드 적응필터의 것과 컴퓨터 모의실험으로 비교하였다.

• 한국음향학회지
• /
• 제12권1호
• /
• pp.37-46
• /
• 1993

The adaptive algorithm for the Volterra filter is considered. Owing to its simplicity, the LMS algorithm for adaptive Volterra filter(AVF) is widely used as in linear adaptive filters. However, the convergence speed is unsatisfactory. For improving the convergence speed, the frequency domain LMS second order adaptive Volterra filter(FLMS-AVF) is proposed and analyzed. We show that the time and frequency domain LMS AVF's have the same steady state performance under approprate conditons. Moreover, it can be shown that this algorithm can improve the convergence speed significantly by applying self-orthogonalizing method.

• 한국지능시스템학회논문지
• /
• 제13권2호
• /
• pp.175-179
• /
• 2003

반복 학습 제어에서 수렴 조건은 수렴 속도와 잔존 오차와 같은 성능을 결정한다. 따라서, 덜 신중한 수렴 조건을 구할 수 있다면, 그 성능은 향상될 것이고 사용 적합한 학습 제어기의 수는 증가된다. 주파수 영역에서, 연속적인 오차들간의 전달 함수의 $H_{\infty}$ 놈(norm)을 학습 시스템의 수렴성을 조사하기 위해 사용해왔다. 그러나, $H_{\infty}$ 놈을 바탕으로 한 수렴 조건이 단조 수렴성에 대하여 명확한 특성을 가진다하더라도, 특히, 다중 입출력 시스템에서 몇 가지 단점을 가진다. 본 논문에서 는 수렴 조건과 수렴의 단조성간의 관계를 밝힌다. 또한 주파수 영역에서 기존의 수렴 조건을 대신할 수 있는 수정된 수렴 조건을 주파수 영역 리아프노프(Lyapunov) 방정식을 이용하여 구한다.

• 한국지구과학회지
• /
• 제41권6호
• /
• pp.670-683
• /
• 2020

본 연구의 목적은 융합적 문제해결력을 검사할 수 있는 도구를 개발하는 것이다. 이를 위해 먼저 선행연구에서 다양하게 정의된 융합적 문제해결력의 영역들을 융합적 성향, 융합적 사고, 융합적 소양 영역 측면으로 정의하였다. 37개의 예비문항은 문제해결과 융합적 사고, 창의적 사고, 개인적 성향과 사회적 성향, 그리고 융합적 소양을 포함한 각 영역에 대한 선행연구에 근거하여 정의된 하위 영역에 근거하여 개발되었다. 탐색적 요인분석을 통해 30개의 예비 문항이 확정 되었다. 확인적 요인 분석 결과는 확정된 5개 요인 모델이 문항수준에서 적합한 요인구조를 가지고 있다는 것을 보여준다. 측정된 모든 문항과 요인에 대한 신뢰도 검정 결과 검사도구 전체의 Cronbach's α값은 .963으로 매우 양호한 것으로 나타났다. 따라서 본 연구에서 개발된 융합적 문제해결 검사 도구는 통계적으로 신뢰롭다고 할 수 있다.

• Journal of Communications and Networks
• /
• 제3권4호
• /
• pp.342-350
• /
• 2001

The Internet routing instability, or the rapid fluctuation of network reachability information, is an important problem currently facing the Internet engineering community. High levels of network instability can lead to packet loss, increased network latency, and delayed routing convergence. At the extreme, high levels of routing instability can lead to the loss of internal connectivity in wide-area networks. In this paper, we investigate the variation of domain degree and domain count of the inter-domain network over time by using linear regression model in order to analyze the topology variation of inter-domain network. We Also propose an efficient policy management model to reduce the instability in the inter-domain routing system. The proposed model can be used to identify whether a routing policy is adequate to reduce convergence time that is required to return to a normal state when BGP routing instability happens. Experimental analysis shows that the proposed model can be used to set up routing policy in domains for the purpose of minimizing the effects and the propagation of BGP routing instability.

• Journal of the Optical Society of Korea
• /
• 제15권3호
• /
• pp.293-299
• /
• 2011

In this study, we demonstrated Fourier-domain/swept-source optical coherence tomography (FD/SS-OCT) at a center wavelength of 800 nm for in vivo human retinal imaging. A wavelength-swept source was constructed with a semiconductor optical amplifier, a fiber Fabry-Perot tunable filter, isolators, and a fiber coupler in a ring cavity. Our swept source produced a laser output with a tuning range of 42 nm (779 to 821 nm) and an average power of 3.9 mW. The wavelength-swept speed in this configuration with bidirectionality is 2,000 axial scans per second. In addition, we suggested a modified zero-crossing method to achieve equal sample spacing in the wavenumber (k) domain and to increase the image depth range. FD/SS-OCT has a sensitivity of ~89.7 dB and an axial resolution of 10.4 ${\mu}m$ in air. When a retinal image with 2,000 A-lines/frame is obtained, an acquisition speed of 2.0 fps is achieved.