• 전자공학회논문지C
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• 제34C권2호
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• pp.50-60
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• 1997

Reconfiguration of a memory array using spare rows and columns has been known to be a useful technique to improve the yield. When the numbers of spare rows and scolumns are limited, respectively, the repair problem is known to be NP-complete. In this paper, we propose the reconfiguration algorithm for an array of memory cells using faulty cel clustering, which removes rows and columns algrithm is the simplest reconfiguration method with the time complexity of $O(n^2)$, where n is the number of faulty cells, however the repair rate is very low. Whereas the exhaustive search algorithm has a high repair rate, but the time complexity is $O(2^n)$. The proposed algorithm provides the same repair rate as the exhaustive search algorithm for almost all cases and runs as fast as the greedy method. It has the time complexity of $O(n^3)$ in the worst case. We show that the propsed algorithm provides more efficient solutions than other algorithms using simulations.

• 대한임베디드공학회논문지
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• 제12권2호
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• pp.71-77
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• 2017

This paper proposes a low complexity frequency modulated continuous wave (FMCW) surveillance radar algorithm. In the conventional surveillance radar systems, the two dimensional (2D) fast Fourier transform (FFT) method is usually employed in order to detect the distance and velocity of the targets. However, in a surveillance radar systems, it is more important to immediately detect the presence or absence of the targets, rather than accurately detecting the distance or speed information of the target. In the proposed algorithm, in order to immediately detect the presence or absence of targets, 1D FFT is performed on the first and M-th bit signals among a total of M beat signals and then a phase change between two FFT outputs is observed. The range of target is estimated only when the phase change occurs. By doing so, the proposed algorithm achieves a significantly lower complexity compared to the conventional surveillance scheme using 2D FFT. In addition, show in order to verify the performance of the proposed algorithm, the simulation and the experiment results are performed using 24GHz FMCW radar module.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권11호
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• pp.5717-5730
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• 2019

LBlock-s is the core block cipher of authentication encryption algorithm LAC, which uses the same structure of LBlock and an improved key schedule algorithm with better diffusion property. Using the differential properties of the key schedule algorithm and the cryptanalytic technique which combines impossible boomerang attacks with related-key attacks, a 15-round related-key impossible boomerang distinguisher is constructed for the first time. Based on the distinguisher, an attack on 22-round LBlock-s is proposed by adding 4 rounds on the top and 3 rounds at the bottom. The time complexity is about only 2^68.76 22-round encryptions and the data complexity is about 2⁵⁸ chosen plaintexts. Compared with published cryptanalysis results on LBlock-s, there has been a sharp decrease in time complexity and an ideal data complexity.

• 한국통신학회논문지
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• 제34권4C호
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• pp.460-468
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• 2009

OFDM(Orthogonal Frequency Division Multiplexing)이 적용된 MIMO(Multiple-input Multiple-output) 기술은 추가적인 주파수 자원의 할당 없이 채널 용량을 증가시키기 위한 방법으로 주목 받고 있으나, MIMO-OFDM 수신단에서 다른 안테나로부터 동시에 전송된 독립적인 데이터 스트림을 분리할 수 있는 낮은 복잡도의 검출 알고리즘을 개발해야 하는 문제점이 있다. 이 논문에서 제안하는 ULBC QRD-M (Upper-Lower Bounded-Complexity QRD-M) 알고리즘은 최대 복잡도 즉, 복잡도의 상한(upper bound)을 기존의 QRD-M 알고리즘과 동일한 값으로 고정시킴으로써 SD(Sphere Decoding) 알고리즘에서 순시적으로 매우 높은 복잡도를 가지는 문제를 해결하는 동시에, 불필요한 Hypothesis를 제거하여 필요한 계산양을 현저하게 낮출 수 있는 장점이 있다. 분석과 모의실험 결과를 통하여 제안된 알고리즘이 기존의 QRD-M 알고리즘에 비하여 단지 26%의 계산양 만으로도 동일한 BER 성능을 가질 수 있음을 보인다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.1187-1190
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• 1998

In this paper we propose a new efficient generalized sidelobe canceller(GSC) algorithm, using the efficient frequency domain LMS algorithm, which has much less weights to update. We only update part of all the weights according to magnitude of each frequency bin. So, the new proposed GSC algorithm, which is called censored GSC(C-GSC), can greatly reduce the computational complexity.

• Journal of Communications and Networks
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• 제14권2호
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• pp.195-198
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• 2012

An efficient sliding window algorithm employing an adaptive-length guard window for turbo decoders is proposed. The proposed algorithm results in significant complexity reductions, especially for small sliding window lengths where the additional computational complexity required for the guard window is critical.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
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• pp.2196-2199
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• 2003

With the development of digital signal processor(DSP), digital pulse compressor (DPC) is commonly used in radar systems. A DPC is implemented by using finite impulse response(FIR) filter algorithm in time domain or fast Fourier transform(FFT) algorithm in frequency domain. This paper compares the computation complexity tot these two methods and calculates boundary Fm filter taps that determine which of the two methods is better based on computation amount. Also, it shows that the boundary FIR filter taps for DSP, ADSP21060, and those for computation complexity have similar characteristic.

• 한국전자통신학회논문지
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• 제17권6호
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• pp.1055-1062
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• 2022

매시브 배열 안테나를 이용한 매시브 MIMO(: Multi Input Multi Output) 기술을 이용하기 위해서는 신호의 도래각(Angle of Arrival : AOA) 파악이 필수적으로 요구된다. 매시브 배열 안테나를 하면 기존 AOA 추정 알고리즘은 뛰어난 추정 성능을 갖지만, 안테나 요소 수에 비례하여 계산복잡도가 증가하는 단점이 있다. 이러한 문제를 해결하기 위해 캐스케이드 AOA 추정 알고리즘이 제안되었으며 다수의 논문을 통해 단일 형상의 (비)매시브 배열 안테나에 대한 성능이 입증되었다. 하지만 단일 및 이중 림 어레이 안테나가 적용된 캐스케이드 AOA 추정 알고리즘의 계산복잡도 비교는 이루어지지 않았다. 본 논문에서는 단일 및 이중 림 어레이를 캐스케이드 AOA 추정 알고리즘에 적용된 경우 AOA 추정을 위한 계산복잡도를 비교 분석한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권6호
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• pp.2446-2462
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• 2016

In this paper, a frequency domain Expectation-Maximization (EM)-based channel estimation algorithm for Space Time Block Coded-Orthogonal Frequency Division Multiplexing (STBC-OFDM) systems is investigated to support higher data rate applications in wireless communications. The computational complexity of the frequency domain EM-based channel estimation is increased when higher order constellations are used because of the ascending size of the search set space. Thus, a search set reduction algorithm is proposed to decrease the complexity without sacrificing the system performance. The performance results of the proposed algorithm is obtained in terms of Bit Error Rate (BER) and Mean Square Error (MSE) for 16QAM and 64QAM modulation schemes.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2013년도 하계학술대회
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• pp.173-175
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• 2013

In this paper, we propose a fast and low-complexity Motion Estimation (ME) algorithm for High Efficiency Video Coding (HEVC). Motion estimation occupies 77~81% of the amount of computation in HEVC. After all, the main key of codec implementation is to find a fast and low-complexity motion estimation algorithm and architecture. The proposed algorithm uses only 1% of the amount of operations compared to full search algorithm while maintaining compression performance with slight loss of 0.6% (BDBR).