• Geophysics and Geophysical Exploration
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• v.7 no.4
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• pp.245-250
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• 2004

Horizontal-axes on the seismic section have been represented in a distance unit by applying horizontal-distance correction transformation on a 2-D seismic section of single channel marine seismic data. By drawing horizontal-axes in a distance unit, distortion of horizontal distances shown on the seismic section when the ship speed varies during a survey can be diminished considerably. Position information obtained by GPS and stored in each trace of seismic data as well as data collection windows were used for horizontal distance correction. The minimum window length was decided by considering ship speed and shot interval, and the maximum window length wat determined by reflecting radius of the 1st Fresnel zone. In choosing an optimum window length, horizontal resolution and stacking effect were considered simultaneously. By applying horizontal distance correction we could get a 2-D seismic section which is considered at reflecting the real subsurface structure analogously.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.15-18
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• 2006

비디오를 내용 별로 분할하기 위한 최소 단위는 비디오의 샷이다. 따라서 비디오 내용 정보를 분석함에 있어서 비디오의 샷 경계 검출은 필수적인 과정이다. 이러한 샷 전환 과정은 급격한 샷 전환 과정과 점진적인 샷 전환 과정으로 구분할 수 있다. 점진적인 샷 전환 과정의 경우 전환 과정이 여러 프레임들에 걸쳐 발생되는 관계로 점진적인 샷 전환 과정을 검출하기 위하여, 기존 샷 경계 검출 알고리즘은 일정 간격을 슬라이딩한 윈도우 프레임들 간의 차이를 비교하는 방식을 이용하였다. 기존 슬라이딩 윈도우 방법은 점전적인 샷 전환 과정을 검출하기 위하여 고정된 크기의 윈도우 하나만을 이용하였다. 이 경우, 슬라이딩 윈도우의 길이가 점진적인 샷 전환 과정에 비해 짧으면, 샷 전환을 검출하지 못 한다. 슬라이딩 윈도우의 길이가 샷의 길이보다 길면 샷을 점진적인 샷 전환으로 검출하는 오류가 발생된다. 상기 문제점을 개선하기 위하여 본 논문에서는 서로 다른 크기의 다수의 슬라이딩 윈도우들과 적응적 경계치를 적용한 샷 경계 검출 방법을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8A
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• pp.1218-1226
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• 1999

In decoding the turbo codes, the sliding window BCJR algorthm, derived from the BCJR algorithm, permits a continuous decoding of the coded sequence without requiring trellis fermination of the constituent codes and uses reduced memory span. However, the number of computation required is greater than that of BCJR algorithm and no study on the effect of the window length has been reported. In this paper, we propose an eddicient sliding window type scheme which maintains the advantages of the conventional sliding window algorithm, reduces its computational burdens, and improves is BER performance. A guideline is first presented to determine the proper window length and then a computationally efficient sliding window BCJR algorithm is obtained by allowing the window to be forwarded in multi-step. Simulation results show that the proposed scheme outperforms the conventional sliding window BCJR algorithm with reduced complexity. It gains 0.1dB SNR improvements over the conventional method for the constraint length 3 and BER $10^{-4}$

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5A
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• pp.426-432
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• 2007

The MAP algorithm is designed and implemented through the sliding window method for turbo decoding. First, the implementation issues, which are the length of the sliding window and the normalization method of state metrics are reviewed, and their optimal values are obtained by the simulation. All component schemes of the decoder including the branch metric evaluator are also presented. The proposed MAP architecture can be easily redesigned according to the size of sliding window, that is, sub-frame length because of its simplicity on buffer control.

• Journal of IKEEE
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• v.21 no.3
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• pp.284-287
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• 2017

In this study, we examined the simulated electrical characteristics of single-gated feedback field effect transistors (FBFETs) and the influence of channel length variation of the memory window characteristics through the 3D device simulation. The simulations were carried out for various channel lengths from 50 nm to 100 nm. The FBFETs exhibited zero SS(< 1 mV/dec) and a current $I_{on}/I_{off}$ ratio${\sim}1.27{\times}10^{10}$. In addition, the memory windows were 0.31 V for 50 nm-channel-length devices while no memory windows were observed for 100 nm-channel-length devices.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 1995.11a
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• pp.151-162
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• 1995

보다 짧은 길이의 덧셈/뺄셈 사슬($addition_{traction-chain}$)을 찾는 문제는 정수론을 기반으로 하는 많은 암호시스템들에 있어서 중요한 문제이다. 특히, RSA에서의 모듈라멱승(modular exponentiation)이나 타원 곡선(elliptic curve)에서의 곱셈 연산시간은 덧셈사슬(addition-chain) 또는 덧셈/뺄셈 사슬의 길이와 정비례한다 본 논문에서는 덧셈/뻘셈 사슬을 구하는 새로운 알고리즘을 제안하고, 그 성능을 분석하여 기존의 방법들과 비교한다. 본 논문에서 제안하는 알고리즘은 작은윈도우(small-window) 기법을 기반으로 하고, 뺄셈을사용해서 윈도우의 개수를 최적화함으로써 덧셈/뺄셈 사슬의 길이를 짧게 한다. 본 논문에서 제안하는 알고리즘은 512비트의 정수에 대해 평균길이 595.6의 덧셈/뺄셈 사슬을 찾는다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.3
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• pp.639-648
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• 2017

Electronic warfare systems for extracting information of the threat signals can be employed under the circumstance where the power of the received signal is weak. To precisely and rapidly detect the threat signals, it is required to use methods exploiting whole energy of the received signals instead of conventional methods using a single received signal input. To utilize the whole energy, numerous sizes of windows need to be implemented in a detector for dealing with all possible unknown length of the received signal because it is assumed that there is no preliminary information of the uncooperative signals. However, this grid search method requires too large computational complexity to be practically implemented. In order to resolve this complexity problem, an approach that reduces the number of windows by selecting the smaller number of representative windows can be considered. However, each representative window in this approach needs to cover a certain amount of interval divided from the considering range. Consequently, the discordance between the length of the received signal and the window sizes results in degradation of the detection performance. Therefore, we propose the weighted energy detector which results in improved detection performance comparing with the conventional energy detector under circumstance where the window size is smaller than the length of the received signal. In addition, it is shown that the proposed method exhibits the same performance under other circumstances.

• Annual Conference on Human and Language Technology
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• 2012.10a
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• pp.40-44
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• 2012

어휘가 갖는 의미적 중의성은 자연어의 특성 중 하나로 자연어 처리의 정확도를 떨어트리는 요인으로, 이러한 중의성을 해소하기 위해 언어적 규칙과 다양한 기계 학습 모델을 이용한 연구가 지속되고 있다. 의미적 중의성을 가지고 있는 동형이의어의 의미분별을 위해서는 주변 문맥이 가장 중요한 자질이 되며, 자질 정보를 추출하기 위해 사용하는 문맥 창의 크기는 중의성 해소의 성능과 밀접한 연관이 있어 신중히 결정되어야 한다. 본 논문에서는 의미분별과정에 필요한 문맥을 가변적인 크기로 사용하는 가변길이 윈도우 방식을 제안한다. 세종코퍼스의 형태의미분석 말뭉치로 학습하여 12단어 32,735문장에 대해 실험한 결과 용언의 경우 평균 정확도 92.2%로 윈도우를 고정적으로 사용한 경우에 비해 향상된 결과를 보였다.

• The Journal of the Acoustical Society of Korea
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• v.37 no.2
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• pp.110-117
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• 2018

In this paper, we propose a low delay window switching MDCT (Modified Discrete Cosine Transform) method for speech/audio coder. The window switching algorithm is used to reduce the degradation of sound quality in non-stationary trasient duration and to reduce the algorithm delay by using the low delay TDAC (Time Domain Aliasing Cancellation). While the conventional window switching algorithms uses overlap-add with different lengths, the proposed method uses the fixed overlap add length. It results the reduction of algorithm delay by half and 1 bit reduction in frame indication information by using 2 window types. We apply the proposed algorithm to G.729.1 based on MDCT in order to evaluate the performance. The propose method shows the reduction of algorithm delay by half while speech quality of the proposed method maintains same as the conventional method.

• The KIPS Transactions:PartD
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• v.12D no.3 s.99
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• pp.345-354
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• 2005

Subsequence matching is one of the most important operations in the field of data mining. The existing subsequence matching algorithms use only one index, and their performance gets worse as the difference between the length of a query sequence and the site of windows, which are subsequences of a same length extracted from data sequences to construct the index, increases. In this paper, we propose a new subsequence matching method based on index interpolation to overcome such a problem. An index interpolation method constructs two or more indexes, and performs search ing by selecting the most appropriate index among them according to the given query sequence length. In this paper, we first examine the performance trend with the difference between the query sequence length and the window size through preliminary experiments, and formulate a search cost model that reflects the distribution of query sequence lengths in the view point of the physical database design. Next, we propose a new subsequence matching method based on the index interpolation to improve search performance. We also present an algorithm based on the search cost formula mentioned above to construct optimal indexes to get better search performance. Finally, we verify the superiority of the proposed method through a series of experiments using real and synthesized data sets.