• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.115-118
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• 2002

This paper presents the design method and performance characteristics of a chip-type quadrature hybrid using LTCC-MLC technology. The design method for a chip-type quadrature hybrid is based on lumped element equivalent circuit of quarter-wave transformer. The chip-type quadrature hybrid was miniaturized to a greater extent using multilayer structure and lumped element. The proposed design method can also reduce the undesirable parasitic effects of the chip-type quadrature hybrid. The proposed chip-type quadrature hybrid was designed and fabricated using the proposed design method and the equivalent circuit model of a quarter-wave transformer. Fabrication and measurement of designed chip-type quadrature hybrid show much smaller size than a conventional distributed quadrature hybrid and a good agreement with simulated results.

• Current Optics and Photonics
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• 제3권3호
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• pp.204-209
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• 2019

In an optical interferometer that uses sinusoidal modulation and quadrature detection, the amplitude and offset of the interference signal vary with time, even without considering system noise. As a result, the circular Lissajous figure becomes elliptical, with wide lines. We propose and experimentally demonstrate a method for compensating quadrature detection error, based on digital signal processing to deal with scaling and fitting. In scaling, fluctuations in the amplitudes of in-phase and quadrature signals are compensated, and the scaled signals are fitted to a Lissajous unit circle. To do so, we scale the average fluctuation, remove the offset, and fit the ellipse to a unit circle. Our measurements of a target moving with uniform velocity show that we reduce quadrature detection error from 5 to 2 nanometers.

• 대한수학회지
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• 제34권4호
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• pp.911-925
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• 1997

We derive quadrature formulas for approximating wavelet coefficients for smooth functions from equally spaced point values with arbitrarily high degree of accuracy. Wa also estimate the error of quadrature formulas.

• 대한전자공학회논문지TC
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• 제37권3호
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• pp.1-8
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• 2000

본 논문에서는 현재 이동통신 시스템의 한 형태로 단말기의 하드웨어 구현이 간단하고 IC제작이 경제적 이어서 무선호출시스템 등에 많이 사용되고 있는 FSK 신호 복조를 위한 Quadrature Detector의 디지털 시뮬레이션 모델을 구현하였다. Quadrature Detector는 아날로그 소자로서 입력신호의 주파수에 따라 다른 위상 변화값이 비선형적으로 출력되어 지금까지 시뮬레이션을 통한 정확한 시스템 특성 분석이 어려웠었다. 이에 본 논문에서는 Quadrature Detector를 이용한 FSK 신호의 복조과정을 전개하고 디지털 시뮬레이션 을 수행하여 최적 성능을 도출하였다. 먼저 Quadrature Detector의 시뮬레이션을 위해 RLC 탱크회로 (Tank Circuit)로 구성된 PSN(Phase Shift Network)의 아날로그 전달함수를 First Order Hold 이론을 이용하여 디지털 전달함수로의 등가변환을 유도하였다. 또한 4FSK신호에 대한 Quadrature Detector의 복조신호 출력 형태가 4-level 신호인데, 이를 2개의 비교기(Comparator)만을 사용할 경우 최적 성능을 얻기 위한 임계레벨 결정과 동작 파라메터 Q값 설정방법을 제안하였으며 BER 분석을 통해 검증하였다

• Nuclear Engineering and Technology
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• 제52권6호
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• pp.1137-1147
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• 2020

The discrete ordinates method (S_N) is one of the major shielding calculation method, which is suitable for solving deep-penetration transport problems. Our objective is to explore the available quadrature sets and to improve the accuracy in shielding problems involving strong anisotropy. The linear discontinuous finite-element (LDFE) quadrature sets based on the icosahedron (in short, ICLDFE quadrature sets) are developed by defining projected points on the surfaces of the icosahedron. Weights are then introduced in the integration of the discontinuous finite-element basis functions in the relevant angular regions. The multivariate secant method is used to optimize the discrete directions and their corresponding weights. The numerical integration of polynomials in the direction cosines and the Kobayashi benchmark are used to analyze and verify the properties of these new quadrature sets. Results show that the ICLDFE quadrature sets can exactly integrate the zero-order and first-order of the spherical harmonic functions over one-twentieth of the spherical surface. As for the Kobayashi benchmark problem, the maximum relative error between the fifth-order ICLDFE quadrature sets and references is only -0.55%. The ICLDFE quadrature sets provide better integration precision of the spherical harmonic functions in local discrete angle domains and higher accuracy for simple shielding problems.

• 대한의용생체공학회:의공학회지
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• 제19권2호
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• pp.129-132
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• 1998

이 논문의 목적은 척추 영상을 위한 One-channel phased-array quadrature RF 코일을 개발하는 것이다. 두 개의 수직방향 RF 코일을 조합하여 만든 Quadrature RF코일은 한 개의 코일을 쓰는 것에 비해 배의 signal-to-noise ratio(SNB) 향상을 얻울 수 있다. Phased-array quadrature RF 코일에서는 코일 element의 크기를 줄임으로써 SNR을 더욱 향상시킬 수 있다. 이에 따라 줄어드는 코일의 Coverage를 유지하기 위해 phased-array 코일에서는 여러 set의 작은 코일을 사용한다. 다음과 같은 두가지 방법으로 Phased-array의 각 코일간의 간섭 현상을 제거했으며 SNR을 개선하였다. (1)인접한 코일을 적당한 간격으로 겹쳐지게 함으로써 상호 인덕턴스를 영으로 만든다. (2)Pro-amp를 코일에 바로 붙임으로써 커플링 회로에서의 SNR loss를 방지하고 그 다음 단에서 코일 사이의 phase차를 보정한다. 이 논문에서는 Receive-only mode의 Phased-array quadrature RF 코일을 개발하여 팬텀과 인체 척추의 영상촬영을 통하여 그 성능을 입증하였다.

• Nonlinear Functional Analysis and Applications
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• 제26권5호
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• pp.935-947
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• 2021

An efficient adaptive scheme based on a triple mixed quadrature rule of precision nine for approximate evaluation of line integral of analytic functions has been constructed. At first, a mixed quadrature rule SM₁(f) has been formed using Gauss-Legendre three point transformed rule and five point Booles transformed rule. A suitable linear combination of the resulting rule and Clenshaw-Curtis seven point rule gives a new mixed quadrature rule SM₁₀(f). This mixed rule is termed as triple mixed quadrature rule. An adaptive quadrature scheme is designed. Some test integrals having analytic function integrands have been evaluated using the triple mixed rule and its constituent rules in non-adaptive mode. The same set of test integrals have been evaluated using those rules as base rules in the adaptive scheme. The triple mixed rule based adaptive scheme is found to be the most effective.

• Journal of applied mathematics & informatics
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• 제4권1호
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• pp.179-192
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• 1997

An algorithm to get an optimal choice for the number of symmetric quadrature points is given to find symmetric quadrature points is given to find symmetric quadrature for-mulas over a unit disk with a minimal number of points even when a high degree of polynomial precision is required. The symmetric quad-rature formulas for numerical integration over a unit disk of complete polynomial functions up to degree 19 are presented.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2008년도 정보통신설비 학술대회
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• pp.21-24
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• 2008

In this paper, Designed Quadrature hybrid coupler apply Open-PI equivalent transmission line. Using the proposed structure we achieve significant size reduction with the same results of conventional quadrature hybrid coupler at 912MHz. The measured frequency responses agree well with simulated one.

• Journal of applied mathematics & informatics
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• 제24권1_2호
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• pp.65-79
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• 2007

An optimal 3-point quadrature formula of closed type is derived. It is shown that the optimal quadrature formula has a better error bound than the well-known Simpson's rule. A corrected formula is also considered. Various error inequalities for these formulas are established. Applications in numerical integration are given.