• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.1
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• pp.15-20
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• 2004

We presented the optical reconstruction system of complex hologram and theoretically demonstrated that the proposed system could display complex hologram. And we made the complex hologram of a three-dimensional image using the modified triangular interferometer, and presented and analyzed the three-dimensional images numerically and optically reconstructed from it.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1940-1943
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• 2003

본 논문은 Polynomial 변환을 이용하여 2차원 Discrete Cosine Transform (2D-DCT)의 계산을 1차원 DCT로 변환하여 계산하는 알고리즘을 개발한다. 기존의 일반적인 알고리즘인 row-column이 N×M의 2D-DCT에서 3/2NMlog₂(NM)-2NM＋N＋M의 합과 1/2NMlog₂(NM)의 곱셈이 필요한데 비하여 본 논문에서 제시한 알고리즘은 3/2NMlog₂M ＋NMlog₂N-M-N/2＋2의 합과 1/2NMlog₂M의 곱셈 수를 필요로 한다. 기존의 polynomial 변환에 의한 2D DCT는 Euler 공식을 적용하였기 때문에 복소 연산이 필요하지만 본 논문에서 제시한 polynomial 변환은 DCT의 modular 규칙을 이용하여 2D DCT를 ID DCT의 합으로 직접 변환하므로 복소 연산이 필요하지 않다. 또한 본 논문에서 제시한 알고리즘은 각 차원에서 데이터 크기가 다른 임의 크기의 2차원 데이터 변환에도 적용할 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.2A
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• pp.188-194
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• 2007

In order to become ubiquitous world, the compatibility of wireless machines has become the significant characteristic of a communication terminal. Thus, SDR is the most necessary technology and standard. However, among the environment which has different communication protocol, it's difficult to make a terminal with only hardware using ASIC or SoC. This paper suggests the processor that can accelerate several communication protocol. It can be connected with main-processor, and it is specialized PHY layer of network The C-program that is modeled with the wireless protocol IEEE802.11a and IEEE802.11b which are based on widely used modulation way; OFDM and CDM is compiled with ARM cross compiler and done simulation and profiling with Simplescalar-Arm version. The result of profiling, most operations were Viterbi operations and complex floating point operations. According to this result we suggested a co-processor which can accelerate Viterbi operations and complex floating point operations and added instructions. These instructions are simulated with Simplescalar-Arm version. The result of this simulation, comparing with computing only one ARM core, the operations of Viterbi improved as fast as 4.5 times. And the operations of complex floating point improved as fast as twice. The operations of IEEE802.11a are 3 times faster, and the operations of IEEE802.11b are 1.5 times faster.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.73-76
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• 2003

본 논문에서는 MPEG-2 BC와 AAC의 복호화 과정 중 함성 필터링 과정의 알고리듬을 분석하여 공동된 구조로 연산을 수행한 수 있는 광용 합성 필터 구조에 대하여 논하였다. 제안된 공용 합성 필터 구조는 Regressive 구조를 이용하여 MPEG-2 BC와 AAC의 복호화를 효과적으로 공용 수행하도록 하였다. 제안한 구조는 FFT를 사용할 경우에 필요한 전처리 및 후처리 과정을 고려해주지 않아도 되고 복소수 연산이 아닌 실수연산이 되어 하드웨어 구조가 단순하게 된다. 또한 MPEG-2 AAC의 다양한 윈도우 변환에도 안정적으로 연산되는 구조임을 확인하였다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.15 no.4
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• pp.20-25
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• 1978

Two augmented integrators are sufficient as memory elements to realize an arbitrary second-order voltage transfer funtion which has complex poles in left-half S-plane, where S is a complex variable. The augmented integrator is characterized by transfer funtion B/(S+A), where A and B are real constant.

• The Korean Journal of Rheology
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• v.3 no.2
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• pp.166-174
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• 1991

동일화학종이면서 \ulcorner량이 다른 두 단분산 고분자를 혼합한 2성분 다분산 농축계에 equivalent primitive chain model을 적용하여 사슬주위의 제약완화에 따른 관의 재형성 효 과를 각 사슬의 특성완화시간으로 산정하여 나타내었다. Polystyrene 시료에 대하여 동력하 적 실험을 실시한 결과를 이용하여 사동모델에 따른 각 사슬의 최장완화시간은 복소수 점도 의 허수분분(η＂)대 주파수($\omega$)의 관계, 관의 재형성 시간은 $\omega$ 변화에 따른 storage modulus(G＇) 로부터 각각 도출하였다. 이러한 작업을 통하여 특성완화 시간들이 분자량 및 각 성분 농도에의 의존성을 더욱 상세히 파악할 수 있었다.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1993.07a
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• pp.51-54
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• 1993

수조안 주 실험구간에서의 유황이 주로 파랑에 의해서 영향을 받는 경우에는 실험결과의 정확도는 바로 사용된 조파기의 성능에 의해서 좌우된다. 컴퓨터를 이용한 조파기 제어시스템을 구축하기 위해서는 특정 조파판 운동에 대한 조파판에서의 수면변화 양상을 정확히 예측할 필요가 있다. 본 연구에서는 복소수 해석을 통하여 조파판 전달함수를 재구성하였으며 시간영역에서 전달함수를 개별적으로 구현할 수 있는 수치 필터를 제시한다. (중략)

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.5
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• pp.404-408
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• 2006

This paper presents an anti-windup gain selection method for a complex vector synchronous frame PI current controller. The complex vector PI current controller is more robust to the parameter variation than the state feedback decoupling PI current controller. The complex vector PI current controller also includes an integral term, which can results in windup problem when the controller is saturated due to physical limitation of the system. Furthermore, even an anti-windup is utilized, inappropriate gain can deteriorate the performance of the current controller. Therefore, appropriate anti-windup gain selection method for a complex vector current controller has been proposed based on the mathematical description of the current control system. The superior performance of the current control system with the proposed anti-windup gain has been verified by the experimental results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.5036-5041
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• 2010

This paper introduces the complex-version of an Euclidean distance minimization algorithm based on a set of delta functions. The algorithm is analyzed to be able to compensate inherently the channel phase distortion caused by inferior complex channels. Also this algorithm has a relatively small size of Gaussian kernel compared to the conventional method of using a randomly generated symbol set. This characteristic implies that the information potential between desired symbol and output is higher so that the algorithm forces output more strongly to gather close to the desired symbol. Based on 16 QAM system and phase distorted complex-channel models, mean squared error (MSE) performance and concentration performance of output symbol points are evaluated. Simulation results show that the algorithm compensates channel phase distortion effectively in constellation performance and about 5 dB enhancement in steady state MSE performance.

• The Journal of the Acoustical Society of Korea
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• v.43 no.2
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• pp.253-259
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• 2024

This paper proposes a new speech enhancement model based on a complex nested U-Net with a dual-branch decoder. The proposed model consists of a complex nested U-Net to simultaneously estimate the magnitude and phase components of the speech signal, and the decoder has a dual-branch decoder structure that performs spectral mapping and time-frequency masking in each branch. At this time, compared to the single-branch decoder structure, the dual-branch decoder structure allows noise to be effectively removed while minimizing the loss of speech information. The experiment was conducted on the VoiceBank + DEMAND database, commonly used for speech enhancement model training, and was evaluated through various objective evaluation metrics. As a result of the experiment, the complex nested U-Net-based speech enhancement model using a dual-branch decoder increased the Perceptual Evaluation of Speech Quality (PESQ) score by about 0.13 compared to the baseline, and showed a higher objective evaluation score than recently proposed speech enhancement models.