• Korean Journal of Cognitive Science
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• v.22 no.4
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• pp.347-364
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• 2011

In this paper, we propose a automatic image bases extraction method for visual image reconstruction from brain activity using Non-negative Matrix Factorization (NMF). Image bases are basic elements to construct and present a visual image. Previous method used brain activity that evoked by predefined 361 image bases of four different sizes: $1{\times}1$, $2{\times}1$, $1{\times}2$, $2{\times}2$, and $2{\times}2$. Then the visual stimuli were reconstructed by linear combination of all the results from these image bases. While the previous method used 361 predefined image bases, the proposed method automatically extracts image bases which represent the image data efficiently. From the experiments, we found that the proposed method reconstructs the visual stimuli better than the previous method.

• Review of KIISC
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• v.2 no.4
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• pp.104-109
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• 1992

스위치 이론이나 디지탈 공학$^{2)}$, 정보보호학$^{6.8)}$등의 분야에서 자주 사용되는 많은 함수들은 유한체 GF$(q)^n$에서 GF(q)의 값을 취하는 함수들이다. 특히 q=2인 경우에 함수 f는 쉽게 진리표에 의해 표현된다. 본 글에서는 유한체 위에서 성립하는 행렬 구조를 갖는 대수적 표준형식 변환에 대하여 알아보고, 변환의 계산을 점화적으로 이행해보며, 난수함수의 복잡도에 관한 확률분포를 살펴본다. 대수적 표준형식은 함수의 비선형 위수나 복잡도에 관한 판단에 유용하게 응용할 수 있다.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.2
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• pp.120-126
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• 2004

This study proposed the analysis of mass position detection due to the change of the mass and strifeless of structure by using the original and modified dynamic characteristics. The method is applied to examples of the cantilevers beam and the 3 degrees of freedom system by modifying the mass. The predicted detection of the mass positions and magnitudes are in good agrement with the present study from the structural reanalysis using the modified mass.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.70-71
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• 2000

세슘빔 공진기에서 세슘D$_2$ 전이선으로 광펌핑된 원자가 램지공진기에서 마이크로파의 주파수에 따른 초미세준위의 바닥상태간의 원자밀도 전이에 의한 형광 신호의 분포를 펌핑광의 세기에 따라 관측하였다. 펌핑광의 편광방향이 자기장에 나란한 $\pi$편광일 때 각 제만부준위의 마이크로파 전이 신호는 mF=0을 중심으로 $\pm$mF의 신호세기가 대칭적이었으나 펌핑광의 편광 방향이 자기장에 수직인 $\sigma$ $\pm$ 인 경우에는 비대칭적임을 확인하였다. 이것은 펌핑광의 주파수가 세슘빔 공진기에서의 세슘공진주파수에서 detuning이 있는 것에 의한 것으로 예상하였다. 이를 확인하기 위해 원자밀도행렬방정식으로 세슘빔공진기에서 마이크로파 전이신호를 계산하였다. 펌핑광의 세기와 편광방향, detuning에 따른 마이크로파 전이신호의 분포가 실험치와 잘 일치함을 알 수 있었다. 이 연구는 세슘빔 원자공진기에서 펌핑광의 주파수가 세슘공진주파수에 detuning된 정도를 관측할 수 있는 방법을 제시해 준다. (중략)

• The Korean Journal of Applied Statistics
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• v.20 no.2
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• pp.323-332
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• 2007

We present a new type of portmanteau test in the frequency domain which is derived from the discrete cosine transform(DCT). For the stationary time series, DCT coefficients are asymptotically independent and their variances are expressed by linear combinations of autocovariances. The covariance matrix of DCT coefficients for white noises is diagonal matrix whose diagonal elements is the variance of time series. A simple way to test the independence of time series is that we divide DCT coefficients into two or three parts and then compare sample variances. We also do this by testing the slope in the linear regression model of which the response variables are absolute values or squares of coefficients. Simulation results show that the proposed tests has much higher powers than Ljung-Box test in most cases of our experiments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.361-366
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• 2017

For two given logical expressions and, when expression contains the same part of the logical expression as expression, substituting for that part of expression is called a substituted logic expression. If a substituted relation is established between the logical expressions, there is an advantage in that the number of literals used in the whole logical expression can be greatly reduced. However, if the substituted relation is not established, there is no simplification effect obtained from the substituted expression. Previous methods proposed a way to find substituted relations between logical expressions for the given logical expressions themselves, and to calculate substituted expressions if only substitution is possible. In this paper, a new method for performing substitution with addition and revision of logic terms is proposed in order to perform substitution, even though there is no substituted relation between two logic expressions. The proposed method is efficiently implemented using a matrix that finds terms to be added. Then, by covering the matrix that has added terms, substituted logic expressions are found. Experiment results show that the proposed method for several benchmark circuits can reduce the number of literals, compared to existing synthesis tools.

• Journal of the Institute of Convergence Signal Processing
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• v.3 no.2
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• pp.7-14
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• 2002

This paper proposes a camera motion estimation technique using special relations of motion vectors of geometrically symmetrical triple points of two consecutive views of single camera. The proposed technique uses camera-induced motion vectors and their relations other than feature points and epioplar constraints. As contrast to the time consuming iterations or numerical methods in the calculation of E-matrix or F-matrix induced by epipolar constraints, the proposed technique calculates camera motion parameters such as panning, tilting, rolling, and zooming at once by applying the proposed linear equation sets to the motion vectors. And by devised background discriminants, it effectively reflects only the background region into the calculation of motion parameters, thus making the calculation more accurate and fast enough to accommodate MPEG-4 requirements. Experimental results on various types of sequences show the validity and the broad applicability of the proposed technique.

• The Korean Journal of Applied Statistics
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• v.32 no.2
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• pp.265-276
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• 2019

The document-term frequency matrix is a general data of objects in text mining. In this study, we introduce a traditional term weighting scheme TF-IDF (term frequency-inverse document frequency) which is applied in the document-term frequency matrix and used for text classifications. In addition, we introduce and compare TF-IDF-ICSDF and TF-IGM schemes which are well known recently. This study also provides a method to extract keyword enhancing the quality of text classifications. Based on the keywords extracted, we applied support vector machine for the text classification. In this study, to compare the performance term weighting schemes, we used some performance metrics such as precision, recall, and F1-score. Therefore, we know that TF-IGM scheme provided high performance metrics and was optimal for text classification.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.5
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• pp.506-512
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• 2003

An output multiplexer of manifold type is widely used in a recent satellite transponder f3r its mass and volume reduction. For correct operation, the filter of such a multiplexer must be singly terminated. In this paper, a simple synthesis method of a 6-pole dual-mode singly terminated filter is described. From the transfer function of the filter, network parameters such as in/output terminations and coupling matrix are obtained with the aid of orthogonal projection and plane rotation. The rotation order, pivot, and rotation angle of the plane rotation process are given for easy filter synthesis. Two different-structure filters are taken into consideration and the network parameters of each filter have been obtained from the same transfer function. The method described in this paper can be applied to the other degree singly terminated filter.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.1
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• pp.65-73
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• 1987

An efficient plate bending finite element has been developed using higher-order inplane displacement profiles of the plate. The 6-noded, 21-d.o.f. triangular element including shear deformation effect has been derived from the plate-like continuum by the Galerkin's weighted residual method. Square plate examples were tested with selected element meshes and several aspect ratios for their static behavior under uniformly distributed load. The result of the example tests indicated consistently good performance of the present higher-order plate bending element in comparison with the thin and thick plate solution and other existing finite element solutions.