• 조명전기설비학회논문지
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• 제29권10호
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• pp.89-96
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• 2015

Explicit numerical integration methods for power system transient stability simulation require very small time steps to avoid numerical instability. The EXST1 exciter model is a primary source of fast dynamics in power system transients. In case of the EXST1, the required small integration time step for entire system simulation increases the computational demands in terms of running time and storage. This paper presents a practical exciter model reduction approach which allows the increase of the required step size and thus the method can decrease the computational demands. The fast dynamics in the original EXST1 are eliminated in the reduced exciter model. The use of a larger time step improves the computational efficiency. This paper describes the way to eliminate the fast dynamics from the original exciter model based on linear system theory. In order to validate the performance of the proposed method, case studies with the GSO-37 bus system are provided. Comparisons between the original and reduced models are made in simulation accuracy and critical clearing time.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
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• pp.2451-2454
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• 2003

In this paper, we propose the computation reduction methods of LSP(Line spectrum pairs) transformation that is mainly used in CELP vocoders. In order to decrease the computational time in real root method the characteristic of four proposed algorithms is as the following. First, scheme to reduce the LSP transformation time uses met scale. Developed the second scheme is the control of searching order by the distribution characteristic of LSP parameters. Third, scheme to reduce the LSP transformation time uses voice characteristics. Developed the fourth scheme is the control of searching interval and order by the distribution characteristic of LSP parameters. As a result of searching time, computational amount, transformed LSP parameters, SNR, MOS test, waveform of synthesized speech, speech, spectrogram analysis, searching time reduced about 37.5％, 46.21％, 46.3％, 51.29％ in average, computational amount is reduced about 44.76％, 49.44％, 47.03％, 57.40％. But the transformed LSP parameters of the proposed methods were the same as those of real root method.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2010년도 춘계학술발표논문집 1부
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• pp.257-260
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• 2010

In this paper, we propose the computation reduction methods of LSP(Line spectrum pairs) transformation that is mainly used in CELP vocoders. In order to decrease the computational time in real root method the characteristic of four proposed algorithms is as the following. First, scheme to reduce the LSP transformation time uses mel scale. Developed the second scheme is the control of searching order by the distribution characteristic of LSP parameters. Third, scheme to reduce the LSP transformation time uses voice characteristics. Developed the fourth scheme is the control of searching interval and order by the distribution characteristic of LSP parameters. As a result of searching time, computational amount, transformed LSP parameters, SNR, MOS test, waveform of synthesized speech, spectrogram analysis, searching time is reduced about 37.5%, 46.21%, 46.3%, 51.29% in average, computational amount is reduced about 44.76%, 49.44%, 47.03%, 57.40%. But the transformed LSP parameters of the proposed methods were the same as those of real root method.

• Nuclear Engineering and Technology
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• 제38권3호
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• pp.225-230
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• 2006

With the advent of inexpensive computing power over the past two decades, applications of Monte Carlo radiation transport techniques have proliferated dramatically. At Los Alamos, the Monte Carlo codes MCNP5 and MCNPX are used routinely on personal computer platforms for radiation shielding analysis and dosimetry calculations. These codes feature a rich palette of variance reduction (VR) techniques. The motivation of VR is to exchange user efficiency for computational efficiency. It has been said that a few hours of user time often reduces computational time by several orders of magnitude. Unfortunately, user time can stretch into the many hours as most VR techniques require significant user experience and intervention for proper optimization. It is the purpose of this paper to outline VR strategies, tested in practice, optimized for several common radiation shielding tasks, with the hope of reducing user setup time for similar problems. A strategy is defined in this context to mean a collection of MCNP radiation transport physics options and VR techniques that work synergistically to optimize a particular shielding task. Examples are offered in the areas of source definition, skyshine, streaming, and transmission.

• International Journal of Control, Automation, and Systems
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• 제6권2호
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• pp.180-185
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• 2008

A new method for relative error continuous and discrete time model order reduction is proposed. The reduction technique is based on two recently developed methods, namely frequency domain balanced truncation within a frequency bound and inner-outer factorization techniques. The proposed method is of interest for practical model order reduction because in this context it shows to keep the accuracy of the approximation as high as possible without sacrificing the computational efficiency. Numerical results show the accuracy and efficiency enhancement of the method.

• 한국통신학회논문지
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• 제34권8A호
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• pp.583-591
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• 2009

높은 PAPR을 갖는 직교 주파수 분할 다중 접속 신호는 비선형 왜곡을 발생시키거나, 송신기의 전력 증폭기의 효율을 나쁘게 한다. 그래서 비선형 왜곡을 줄이기 위한 상호 변조 왜곡 저감 기법이 제안되었다. IMD 저감 기법은 비선형 왜곡에 대하여 PAPR 저감 기법보다 비트 오차율 작게 한다. 하지만 IMD 저감 기법의 결정 기준은 주파수 영역에서 이루어지기 때문에 송신기에 FFT가 추가되어 시스템 복잡도가 증가하고, IMD 연산의 복잡한 계산 과정과, 이에 따른 처리시간이 증가하는 문제가 있다. 그러므로 본 논문에서는 이러한 기존의 IMD 저감 기법의 복잡도와 계산량 저감하기 위한 새로운 방식의 IMD 저감 방식을 제안한다. 또한 본 논문에서는 제안된 방식을 PTS 방식의 OFDM 통신 시스템에 적용하여 기존의 기법과 복잡도와 계산량을 비교한다. 제안된 기법은 PAPR처럼 시간영역에서 IMD의 전력량을 계산하므로 송신기에서 시스템의 복잡도와 계산량을 크게 줄일 수 있다. 또한 새로운 기법은 기존 방식과 BER 성능 면에서 차이를 보이지 않는다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.2035-2038
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• 2002

The necessity of the filter coefficients compensation for the LTJ adaptive filter was explained generally and easily by analyzing it with respect to the time-varying transform domain adaptive filter. And also the reduction method of computational complexity for filter coefficients compensation was proposed and its effectiveness was verified through experiments using artificial and real speech signals. The proposed adaptive filter reduces the computational complexity for filter coefficients compensation by 95%, and when the filter is applied to the acoustic echo canceller with 1000 taps, the total complexity is reduced by 82%

• 한국멀티미디어학회논문지
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• 제21권1호
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• pp.18-25
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• 2018

In High Efficiency Video Coding (HEVC), integer motion estimation (IME) requires a large amount of computational complexity because HEVC adopts the high flexible and hierarchical coding structures. In order to reduce the computational complexity of IME, this paper proposes the search range reduction algorithm, which takes advantage of motion vectors similarity between different layers. It needs only a few modification for HEVC reference software. Based on the experimental results, the proposed algorithm reduces the processing time of IME by 28.1% on average, whereas its the $Bj{\emptyset}ntegaard$ delta bitrate (BD-BR) increase is 0.15% which is negligible.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 추계학술대회
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• pp.93-96
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• 2022

DTW는 길이가 서로 다른 시퀀스 사이의 간격을 제거하고 패턴의 유사성을 알아낼 수 있지만, 시공간 복잡성 때문에 대규모 데이터셋에서 많은 계산 비용이 필요로 한다. 본 논문에서는 계산 비용을 줄일 뿐만 아니라 결괏값의 오차도 없는 DDTW 알고리즘을 제안한다. 그리고 시퀀스의 길이에 따른 연산 시간을 측정하여 DTW와 DDTW의 알고리즘 복잡도를 비교한다. 시뮬레이션 결과 DTW에 비해 DDTW에서 연산 시간이 눈에 띄게 줄어듦을 확인하였다.

• 한국전자통신학회논문지
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• 제8권9호
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• pp.1299-1305
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• 2013

이 논문에서 우리는 MFCC 특징벡터의 차원 저감을 통해 음성 인식에서의 계산량을 줄이는 방법을 조사한다. 특징벡터의 특성분해는 벡터의 성분을 분산의 크기에 따라 배치되도록 선형 변환 시켜준다. 첫 번째 성분은 가장 큰 분산을 가져서 패턴 분류에서 가장 중요한 역할을 한다. 따라서, 분산이 작은 성분들을 제외시키는 차원 저감을 통하여, 계산량을 줄이면서 동시에 음성 인식 성능을 저하시키지 않는 방법을 생각할 수 있다. 실험 결과, MFCC 특징벡터의 성분을 절반 정도로 줄여도 음성인식 오류율에 큰 악영향이 없음이 확인되었다.