• International journal of advanced smart convergence
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• 제9권1호
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• pp.98-108
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• 2020

We consider transmit antenna selection combined with power allocation for quadrature spatial modulation (QSM) systems to improve the error rate performance. The Euclidean distance-based joint optimization criterion is presented for transmit antenna selection and power allocation in QSM. It requires an exhaustive search and thus high computational complexity. Thus its reduced-complexity algorithm is proposed with a strategy of decoupling, which is employed to successively find transmit antennas and power allocation factors. First, transmit antennas are selected without considering power allocation. After selecting transmit antennas, power allocation factors are determined. Simulation results demonstrate considerable performance gains with lower complexity for transmit antenna selected QSM systems with power allocation, which can be achieved with limited rate feedback.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.130-133
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• 1999

In the view point of further reducing the inter-symbol interferences studied in our previous paper 〔1〕, a quadrature pair of wavelet-based filter banks that are composed of a pair of cosine and sine modulated filter banks is applied to MC-CDMA transmultiplexing. For that fact, the symbol duration gets twice longer than the one in , 〔1〕, the interference effects due to channel overlapping and Doppler spread can be effectively alleviated while increasing the channel utilization efficiency. Moreover, the well-known wavelet properties are exploited to design the prototype filter in such a way to maintain the size of sidelobes much smaller than those of the FFT, the interference reduction effect can be further obtained. To verify the behavior of our proposed quadrature filter bank based MC-CDMA system, the reverse-link bit error rates with respect to SNR under Rayleigh fading and additive white Gaussian noise channel environments are computed. The results show an improved system performance over the conventional MC-CDMA.

• 전자공학회논문지A
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• 제33A권6호
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• pp.32-41
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• 1996

We propose the improved GMSK (gaussian-filtered minimum shift keying) quadrature modulator using the FIR(finite impulse response )filter whose coefficients are obtained form the differnce of phase response, and design its ASIC (applicaton specific integrated circuit) which can be used for GSM (global system for mobile communication) digital cellular system and DCS 1800 (digital cellular system at 1800MHz) personal communication system. Input data become quantized I and Q channel 10 bit signal through cosine and sine ROM mapping after being filtered by the FIR filter whose normalized bandwidth is 0.3 and designed by considering intersymbol interference as well as sampling ratio. These two signals become the GMSK modulated I and Q channel signal through DAC (digital-to-analog converter) and 7th order analog chebyshev LPF(low pass filter) respectively. The difference between the ideal analog signal and its digitized signal is analyzed in terms of sampling noise, quantization noise, truncation noise and coefficient noise. And the effect of the LPF following the DAC is considered. The ASIC design of the GMSK quadrature modulator is also confirmed by an experiment.

• 한국안전학회지
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• 제12권4호
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• pp.220-229
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• 1997

곡선보(curved beam)의 등분포 하중하에서 평면내(in-plane)와 평면의(out-of-plane)의 좌굴(buckling)을 해석하는데 differential quadrature method (DQM)을 이용하여 다양한 경계조건(boundary conditions)과 굽힘각(opening angles)에 따른 입계하중(critical loads)을 계산하였다. DQM의 해석결과는 해석적 해답(exact solution) 또는 다른 수지해석 결과와 비교하였으며, DQM은 적은 요소(grid points)를 사용하여 정확한 해석결과를 보여주었다. 두 경계조건(고정-고정, 고정-단순지지)하에서 새로운 결과를 또한 제시하였다.

• 대한기계학회논문집A
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• 제30권3호
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• pp.279-286
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• 2006

The main purpose of this paper is to apply differential transformation method(DTM) and generalized differential quadrature method(GDQM) to vibration analysis of Euler-Bernoulli beam with open cracks on elastic foundation. In this paper the concepts of DTM and GDQM were briefly introduced. The governing equation of motion of the beam with open cracks on elastic foundation is derived. The cracks are modeled by massless substitute spring. The effects of the crack location, size and the foundation constants, on the natural frequencies of the beam, are investigated. Numerical calculations are carried out and compared with previous published results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 추계학술대회 논문집
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• pp.56-59
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• 2003

This paper presents new interpolation algorithm for measuring high resolution position information which is propered to nano servo control motor using analog quadrature encoder. In the past, there is a large memory and two high price A/D converter for high resolution analog quadrature encoder interpolation. but this paper show that it can make high resolution interpolate using small memory, one A/D converter and comparator. Experimental results show that the proposed algorithm for high resolution position is useful.

• 한국소음진동공학회논문집
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• 제11권9호
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• pp.462-474
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• 2001

In this paper, Generalized Differential Quadrature Method is applied to the buckling analysis of built-up columns without or with stay plates. numerical analysis using GDQM is carried out for various boundary conditions(simply supported conditions, fixed conditions, fixed-simply supported conditions), dimensionless stiffness parameter and dimensionless inertia moment parameter. The accuracy and convergence of solutions are compared with exact solutions of Gjelsvik to validate the results of GDQM. Results obtained by this method are as follows. 91) This method can yield the accurate numerical solutions using few grid points. (2) The buckling load of built-up column increases as the dimensionless stiffness parameter decreases. (3) The effects of boundary conditions on the buckling load are not considerable as the dimensionless stiffness parameter increases. (4) The buckling load of built-up column increases due to the stay plate.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.188-194
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• 2009

Consolidation settlement, a crucial parameter in geotechnical design of soft ground, has not been computed in a unique way due to different computation methods in practice. To improve computational error in calculating consolidation settlement, a number of researches has been attempted. Conventional 1-dimensional consolidation theory assumes the center of the clay layer as the representative point to obtain effective stress in calculation, which could resort to erroneous results. To calculate exact solutions considering initial distribution of effective stress, diving a stratum into multi-layers could resort to wasting time and effort. In the study, a novel methodology for calculating consolidation settlement via Guassian quadrature is developed. The method generally is capable of computing settlements in any case of the stress conditions encountered in fields.

• 전기의세계
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• 제21권1호
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• pp.7-12
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• 1972

General steady state equivalent circuits are derived for the family of single phase motor having two windings with non-quadrature. First, the fundamental voltage equations of motor are derived by Faraday-Krichhoff's low in the fiew of the flux distribution in the modified motor with Kron primitive machine. Those equations are arranged in to f-b equations by transformation matrix. To using the above equations for circuit; 1) The concept of current-source was much help to sove the realtions between matrix impedance equation and circuit analysis 2) The simplification of the circuit to the mutual impedance matrix elements is easy to considerations of motor characteristics in the case of inserted external auxiliary winding impedance. Finally, this equivalent circuit showing as a single phase induction motor with quadrature winding is described by each conditions.

• Structural Engineering and Mechanics
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• 제10권5호
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• pp.451-462
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• 2000

Buckling loads are determined for thin isotropic circular cylindrical shell panels subject to radial pressure using the new differential quadrature method. The Budiansky stability theory serves as the basis of the analysis. For this problem involving four boundary lines a two-dimensional approach is used, and a detailed convergence study is carried out to determine the appropriate analysis parameters for the method. Numerical results are determined for a total of twelve cylindrical shell panel cases for a number of different boundary support conditions. The results are compared with analytical and finite element method results. Conclusions are drawn about the technical significance of the results and the solution process.