• Bulletin of the Korean Chemical Society
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• 제24권8호
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• pp.1097-1101
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• 2003

The cubic and quartic anharmonic force field of malonaldehyde is calculated using density functional theory at the B3LYP/6-31G(d,p) level, and used to simulate coherent infrared vibrational spectra. 12 normal modes are included in the simulation, and the Arnoldi method is employed for the diagonalization of the Hamiltonian. The calculated three pulse infrared signals in the k1 + k2 - k3 direction show signatures of the intramolecular hydrogen bond couplings between the C=O stretch, H-O-C bend and O-H stretch vibrations.

• 한국음향학회지
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• 제38권2호
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• pp.177-183
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• 2019

본 논문에서는 수동 선배열 소나의 저주파 영역에서 수신된 표적 신호로부터 간섭신호를 분리해 내기 위해 독립성분분석 알고리즘을 적용하는 방안을 제안하고 기존 알고리즘들의 성능을 비교해 보았다. 저주파 대역 신호의 경우 비교적 넓은 방위로부터 수신되기 때문에 인접 빔 신호를 관측신호로 활용하여 독립성분분석을 수행할 수 있다. 신호분리에 사용한 독립성분분석 알고리즘은 FastICA(Fast Independent Component Analysis), NNMF (Non-negative Matrix Factorization), JADE (Joint Approximation Diagonalization of Eigen-matrices)이다. 실측 선배열 수동소나신호를 이용하여 독립성분분석을 수행한 결과 제안한 방법으로 간섭신호분리가 가능함을 확인하였으며, JADE 알고리즘의 신호 분리 성능이 가장 우수한 것으로 나타났다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.169-177
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• 2005

A high resolution scheme for solving gas-liquid two-phase flows with cavitation is described. This scheme uses the curvilinear coordinate grid and solves the density based momentum equations for mixture of gas-liquid medium with a preconditioning method to treat both compressible and incompressible flow characteristics. The present preconditioned method is based on the Runge-Kutta explicit finite-difference scheme, and is improved by using the diagonalization, the flux difference splitting and the MUSCL-TVD schemes to save computational effort and to increase stability and resolvability, especially at gas-liquid contact surfaces. A homogeneous equilibrium cavitation model is used to treat the gas-liquid two-phase medium in cavitating flow as a locally homogeneous pseudo-single-phase medium. Therefore, it is easy to solve cavitating flow, including wave propagation, large density changes and incompressible flow characteristic at low Mach number. Some numerical results obtained by the present scheme are shown.

• 대한전자공학회논문지
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• 제15권4호
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• pp.14-19
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• 1978

본 논문에서는 동시대각화에 의한 일군정규화 및 혼합정규화시의 좌표계의 변환에 간목하여, 두 다변수군간의 특징추출을 행하는 수법을 제안, 그에 수반하는 몇몇의 성질과 고 적용례에 대해 기술했다. 또한 본수법의 유효성을 보이기 위해 인자분석결과와 비교해, 유의한 결과를 얻었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 제13회 신호처리 합동 학술대회 논문집
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• pp.553-556
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• 2000

This paper proposes an adaptive linearization method of Volterra nonlinear systems using DWT(Discrete Wavelet Transform)and an LMS-type predistorter. In particular, the proposed wavelet transform-domain lineatization method leads to diagonalization of the input vector auto-correlation matrix which yields improvement of the convergence rate of the corresponding transform-domain LMS algorithm. Furthermore, the adaptive Volterra predistorter followed by a corresponding weakly Volterra nonlinear system(here. a TWT amplifier model in a satellite communication system) is utilized to compensate for the distortion in the output. Also,12-PSK and 4-QAM are applied as the input to the nonlinear system to be tested. Some simulation results show that the proposed linearization approach has better performance than DCT-based or conventional normalized LMS algorithms do.

• Journal of Communications and Networks
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• 제17권3호
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• pp.241-246
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• 2015

In this paper, we consider a relaying system which employs a single relay in a wireless network with distributed sources and destinations. Here, all source, destination, and relay nodes are equipped with multiple antennas. For amplify-and-forward relay systems, we confirm the achievable sum rate through a joint multiple source precoders and a single relay filter design. To this end, we propose a new linear processing scheme in terms of maximizing the sum rate performance by applying a blockwise relaying method combined with geometric programming techniques. By allowing the global channel knowledge at the source nodes, we show that this joint design problem is formulated as a standard geometric program, which can guarantees a global optimal value under the modified sum rate criterion. Simulation results show that the proposed blockwise relaying scheme with the joint power allocation method provides substantial sum rate gain compared to the conventional schemes.

• 전기전자학회논문지
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• 제18권2호
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• pp.255-262
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• 2014

The uncertain integral linear system is the integral-augmented uncertain system to improve the resultant performance. In this note, for a MI(Multi Input) uncertain integral linear case, Utkin's theorem is proved clearly and comparatively. With respect to the two transformations(diagonalizations), the equation of the sliding mode is invariant. By using the results of this note, in the SMC for MIMO uncertain integral linear systems, the existence condition of the sliding mode on the predetermined sliding surface is easily proved. The effectiveness of the main results is verified through an illustrative example and simulation study.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2008년도 정보통신설비 학술대회
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• pp.12-16
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• 2008

In this paper, we study precoding techniques for co-channel interference suppression in multiuser MIMO systems. DPC is optimal techniques to achieve the system capacity of multiuser MIMO downlink channels. DPC is not proper in practical wireless systems because complexity is very high. So block diagonal precoding for multiuser MIMO downlink channel is studied. The block diagonal precoding is used to suppress co-channel interference between multiuser. Block diagonal precoding method, whose complexity is reduced by modified null space operation, change multiuser MIMO channel to multiple single-user MIMO channel. We also use V-BLAST decoder in receiver. V-BLAST decoder can achieve increased system capacity in proportion to the number of users. We show improved system performance by using computer simulation.

• Transactions on Control, Automation and Systems Engineering
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• 제3권4호
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• pp.242-249
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• 2001

In this paper, the open-loop state response of the two-time-scale systems by unified approach using the $\delta$-operator is presented with an example of the aircraft longitudinal dynamics. First, the $\delta$-operator system unifies both the continuous system and the discrete system simultaneously, and the $\delta$-operator approach improves the finite word-length characteristics. This saves more computing time than that of the discrete system. Second, the singular perturbation method by block diagonalization reduces the sizes and orders of the systems. This also reduces the floating-point operations (flops). The advantage of those two approaches is shown by comparing our results with the earlier ones in the illustrative example of the longitudinal motion of F-8 aircraft.

• 한국항공우주학회지
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• 제32권7호
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• pp.76-82
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• 2004

본 논문에서는 델타연산자를 이용한 통합시스템에서 사전에 민감도가 낮게 설정된 폐루프 궤적을 성취해주는 상태 궤환 제어기의 설계기법이 제안되었다. 양시등급 시스템에서는 빠른 모드를 무시함으로써 수행되는 특이섭동기법에 의해서 그 차수가 감소된다. 제안된 기법은 특이성동상수의 범위에서 실제 궤적의 변화를 다룬다. 물론 최적화를 위한 필요조건들도 유도된다. 이전의 연구는 연속시스템에서 이루어졌으나 본 논문에서는 이산 시스템 및 델타통합시스템으로 확장하였다. 제안된 기법의 우수성은 수치예제를 통하여 확인되었다.