• Title/Summary/Keyword: Complex Conjugate

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Complex Conjugate Resolved Retinal Imaging by One-micrometer Spectral Domain Optical Coherence Tomography Using an Electro-optical Phase Modulator

  • Fabritius, Tapio E.J.;Makita, Shuichi;Yamanari, Masahiro;Myllyla, Risto A.;Yasuno, Yoshiaki
    • Journal of the Optical Society of Korea
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    • v.15 no.2
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    • pp.111-117
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    • 2011
  • Full-range spectral domain optical coherence tomography (SD-OCT) with a 1-${\mu}m$ band light source is shown here. The phase of the reference beam is continuously stepped while the probing beam scans the sample laterally (B-scan). The two dimensional spectral interferogram obtained is processed by a Fourier transform method to obtain a complex spectrum leading to a full-range OCT image. A detailed mathematical explanation of the complex conjugate resolving method utilized is provided. The system's measurement speed was 7.96 kHz, the measured axial resolution was $9.6{\mu}m$ in air and the maximum sensitivity 99.4 dB. To demonstrate the effect of mirror image elimination, In vivo human eye pathology was measured.

The application of eigenstructure assignment to flight control system (비행제어계에 대한 고유구조 할당의 응용)

  • 박노웅;박정일;박종국
    • 제어로봇시스템학회:학술대회논문집
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    • pp.603-607
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    • 1988
  • On this paper, the application of Eiganstructure assignment to flight control system design is presents. Both output feedback and constrained output feedback are considered. The computer implimentation of the algorithm is discussed including the utilization of real arithmetic for complex conjugate eigenvalue. And the example include a stability augementation system, an autopilot decoupled mode control.

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A Study on the Effects of Added Zeros to the System with a Monotone Nondecreasing Step Response

  • Kwon, Byung-Moon;Lee, Hyun-Seok;Kwon, Oh-Kyu
    • 제어로봇시스템학회:학술대회논문집
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    • pp.44.4-44
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    • 2002
  • This paper investigates some conditions such that zeros are added to the system with a monotone nondecreasing step response in order to hold the monotonicity as before. Two conditions are presented for the cases that a real zero and complex conjugate zeros are added to the system satisfying the monotonicity condition, respectively. To exemplify the proposed results, some simple examples via computer simulation are shown in this paper. Proposed conditions can be easily used in the control system design since they are only formulated in terms of pole-zero configurations.

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GENERALIZATION OF A COMPLEX-SYSTEMS EQUIVALENT TRANSFORM IN THE DISCRETE SENSE

  • Koga, Masanobu;Furuta, Katsuhisa
    • 제어로봇시스템학회:학술대회논문집
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    • pp.1699-1704
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    • 1991
  • The states, inputs, outputs and parameters of a complex-system are all complex values. The introduction of such complex systems makes it more suitable to treat not only the robust control but also the pole assignment in the separate regions. The relation called "equivalence in the discrete sense" is introduced to define a complex-system corresponding to a real-system with real-axis poles as well as complex conjugate poles. The relation between the feedback-control laws of the equivalent systems in the discrete sense are derived so that their closed-loop systems should hold the equivalence in the discrete sense.ete sense.

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A Study on the Pitch Search Time Reduction of G.723.1 Vocoder by Improved Hybrid Domain Cross-correlation (개선된 혼성영역 교차상관법에 의한 G.723.1의 피치검색시간 단축에 관한 연구)

  • Jo, Wang-Rae;Choi, Seong-Young;Bae, Myung-Jin
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.12
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    • pp.2324-2328
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    • 2010
  • In this paper we proposed a new algorithm that can reduce the open-loop pitch estimation time of G.723.1. The time domain cross-correlation method is simple but has long processing time by recursive multiplication. For reduction of processing time, we use the method that compute the cross-correlation by multiplying the Fourier value of speech by it's complex conjugate. Also, we can reduce the processing time by omitting the bit-reversing of FFT and IFFT for time-frequency domain transform. As a result, the processing time of improved hybrid domain cross-correlation algorithm is reduced by 67.37% of conventional time domain cross-correlation.

Datuming by Wavefield Depth Extrapolation (파동장 외삽을 이용한 데이터밍)

  • Ji Jun
    • Geophysics and Geophysical Exploration
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    • v.1 no.2
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    • pp.116-126
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    • 1998
  • I present a datuming scheme for poststack data that uses wavefield depth extrapolation. The method I have developed allows the use of any depth extrapolation technique, such as phase-shift, split-step, and finite-difference extrapolation. I derive the datuming algorithms by transposing and taking the complex conjugate (i.e. taking adjoint) of the corresponding forward modeling operator, which does upward extrapolation from a flat surface to an irregular surface. The exact adjoint relation between the forward modeling operator and the datuming operator is demonstrated algebraically. Testing the poststack datuming algorithms with synthetic data, using several depth extrapolation algorithms, has shown that the method works well.

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Zeros and Step Response αlaracteristics in LTI SISO Systems (선형시불변 단일입출력 시스템의 영점과 계단응답 특성)

  • Lee, Sang-Yong
    • Journal of Institute of Control, Robotics and Systems
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    • v.15 no.8
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    • pp.804-811
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    • 2009
  • This paper deals with the relationship between zeros and step response of the second and third order LTI(Linear Time Invariant) SISO(Single-Input and Single-Output) systems. As well known, if a system has a single unstable zero, it shows the step response with undershoot and, on the other hand, a stable zero slower than the dominant pole causes the system to have the step response with overshoot. Generally, in the case of a system with two unstable real zeros, it is known to have B type undershoot[7]. But there are many complex cases of the step response extrema corresponding to zeros location in third order systems. This paper investigates the whole cases depending on DC gains of the additive equivalence systems and they are to be classified by the region of zeros which are related to the shape of the step response. Moreover, monotone nondecreasing conditions are proposed in the case of complex conjugate zeros as well as the case of two stable zeros.

Time Reversa1 Reconstruction of Ultrasonic Waves in Anisotropic Media

  • Jeong, Hyun-Jo
    • Journal of the Korean Society for Nondestructive Testing
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    • v.28 no.1
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    • pp.54-58
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    • 2008
  • Time reversal (TR) of body waves in fluids and isotropic solids has been used in many applications including ultrasonic NDE. However, the study of the TR method for anisotropic materials is not well established. In this paper, the full reconstruction of the input signal is investigated for anisotropic media using an analytical formulation, called a modular Gaussian beam (MGB) model. The time reversal operation of this model in the frequency domain is done by taking the complex conjugate of the Gaussian amplitude and phase received at the TR mirror position. A narrowband reference signal having a particular frequency and number of cycles is then multiplied and the whole signal is inverse Fourier transformed. The original input signal is seen to be fully restored by the TR process of MGB model and this model can be more generalized to simulate the spatial and temporal focusing effects due to TR process in anisotropic materials.

Heat Transfer Analysis of a Linear Motor for Chip Mounter Applications (칩 마운터용 리니어 모터의 열전달 해석)

  • Jang, Chang-Soo;Kim, Jong-Young;Kim, Yung-Joon;Oh, Jung-Suk
    • Proceedings of the KSME Conference
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    • pp.396-401
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    • 2001
  • Heat transfer analysis of a iron core type linear motor for surface mounting device applications was considered in this study. In order to avoid the complex conjugate problem a fluid flow regime and a solid regime were considered separately. First, film coefficients of the moving parts were evaluated from computational fluid dynamic analysis and those of the stationary parts from the existing empirical or analytic correlations. And then, by applying them, internal and external temperatures of the linear motor pal1s were computed through finite element analysis. Both computation and measurement were carried out with respect to motor driving power. The measurement did not exhibit a linear temperature variation trend with respect to motor power while the computation revealed a linear correlation. Nonetheless, the computations agreed with the measurements within an error range of 20%. It indicates that an adequate heat transfer model for the reciprocative coil assembly may help more exact prediction.

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RFID Tag Antenna Mountable on High-Conductivity and High Permittivity an Materials at UHF Band (고 전도율과 고 유전율 물질에 부착 가능한 RFID 태그 안테나)

  • Kwon Hong-Il;Lee Bom-Son
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.8
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    • pp.797-802
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    • 2005
  • In this paper, we design a UHF band RFID tag antenna which is conjugate matched to an impedance of a chip and also mountable on conductive materials. The proposed tag antenna is very compact($50{\times}30{\times}4mm$) with a modified PIFA shape. The proposed tag antenna has an advantage of easy matching to various chip input impedances. The performance of the antenna is evaluated by monitoring RCS in the reader direction. The RCS of the designed tag is $-10.2\;dBm^2$ when the chip is shorted and is $-21\;dBm^2$ when the chip impedance is a complex conjugate of the antenna impedance.