• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1A
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• pp.84-92
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• 2004

Eigenstructure-based adaptive beamfoming has advantages of fast convergence and the insentivity to errors in the arrival angle of the desired signal. Eigen-decomposing the sample matrix to extract a basis for the Sl (signal plus interference) subspace, however, is very computationally expensive. In this paper, we present a simple subspace based beamforming which utilizes off-diagonal elements of the sample matrix to estimate the Sl subspace. The outputs of overlapped subarrays are combined to produce the final adaptive output, which improves SINR (signal-to-interference-plus-noise ratio) comapred to exploiting a single subarray. The proposed adaptive beamformer, which employs an efficient angle estimation is very roubust to errors in both the arrival angles and the number of the incident signals, while the eigenstructure-based beamforer suffers from severe performance degradation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.1
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• pp.157-163
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• 1986

A method to improve the Finite Elements Model and to identify structure stiffness damages utilizing measured dynamic characteristics is suggested. In order to show the effectiveness of the proposed method, a sample structure is adopted and tested. It is found that; (1) the Finite Elements Model can be improved with experimentally obtained dynamic characteristics satisfactorily and (2) the test results are also very helpful to search the stiffness damaged part of the sample structure via plotting the error matrix[E], especially it is aboved that the weighted error matrix is very effective to detect even the stiffness changes are relatively small.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.3
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• pp.1243-1263
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• 2018

The two-stage linear discrimination analysis (TSLDA) is a feature extraction technique to solve the small size sample problem in the field of image recognition. The TSLDA has retained all subspace information of the between-class scatter and within-class scatter. However, the feature information in the four subspaces may not be entirely beneficial for classification, and the regularization procedure for eliminating singular metrics in TSLDA has higher time complexity. In order to address these drawbacks, this paper proposes an improved two-stage linear discriminant analysis (Improved TSLDA). The Improved TSLDA proposes a selection and compression method to extract superior feature information from the four subspaces to constitute optimal projection space, where it defines a single Fisher criterion to measure the importance of single feature vector. Meanwhile, Improved TSLDA also applies an approximation matrix method to eliminate the singular matrices and reduce its time complexity. This paper presents comparative experiments on five face databases and one handwritten digit database to validate the effectiveness of the Improved TSLDA.

• Communications of Mathematical Education
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• v.22 no.4
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• pp.515-531
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• 2008

The visual cryptography scheme is a simple method which can be decoded directly the secret information in human visual system without performing any cryptographic computations. For some secret of image type, we scatter them to random n images and if any threshold (or more) of them are stacked together then original image is visible. In this paper we consider (2,n) visual cryptography scheme and show a construction method of the sample matrix using the rule of binomial coefficients $_nC_2$. This scheme can contribute interesting and effectiveness to the study of mathematics.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.4
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• pp.251-258
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• 1986

There is much redundancy in image data such as TV signals and many techniques to redice it have been studied. In this paper, Hadamard transform is studied through computer simulation and experimental model. Each element of hadamard matrix is either +1 or -1, and the row vectors are orthogonal to another. Its hardware implementation is the simplest of the usual orthogonal transforms because addition and sulbraction are necessary to calculate transformed signals, while not only addition but multiplication are necessary in digital Fourier transform, etc. Linclon data (64$ imes$64) are simulated using 8th-order and 16th-order Hadamard transform, and 8th-order is implemented to hardware. Theoretical calculation and experimental result of 8th-order show that 2.0 bits/sample are required for good quality.

• The Korean Journal of Applied Statistics
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• v.35 no.1
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• pp.77-91
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• 2022

The optimal threshold estimation is considered in order to discriminate the mixture distribution in the fields of Biostatistics and credit evaluation. There exists well-known various accuracy measures that examine the discriminant power. Recently, Matthews correlation coefficient and the F1 statistic were studied to estimate optimal thresholds. In this study, we explore whether these accuracy measures are appropriate for the optimal threshold to discriminate the mixture distribution. It is found that some accuracy measures that depend on the sample size are not appropriate when two sample sizes are much different. Moreover, an alternative method for finding the optimal threshold is proposed using the correlation coefficient that defines the ratio of the confusion matrix, and the usefulness and utility of this method are also discusses.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1234-1235
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• 2008

To add Nanofiller in the epoxy which is used with the solid insulation material of existing and is a research which observes the improvement of the structural quality to produce the Nanocomposite. Montmorillonite uses with Nanofiller, MMT of the content expense (wt%) which is various and mixed an epoxide and produced sample. According to content of the sample result MMT according to respectively content expense to measure SEM photographing which is the possibility of knowing the minute structure of section with sample where is produced and the tensile strength will be able to observe the change of quality. MMT silicate layer uniformly more in the result and within epoxy matrix, being dispersed, will be able to observe.

• Resources Recycling
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• v.26 no.4
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• pp.50-55
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• 2017

Determination of trace elements in a sample including complicated matrix is very difficult due to the interference by the matrix. Therefore, if the trace elements can be separated from the complex sample matrix and determined, the interference effects can be reduced, and it is very helpful for the overall analysis. In this study, the analytes of trace elements were separated from the sample matrix by co-precipitation with trace elements using indium hydroxide ($In(OH)_3$), then detected by inductively coupled plasma-atomic emission spectrometer (ICP-AES). Above all, the optimal conditions for the co-precipitation of elements with indium hydroxide were experimentally established. At last, salt was analyzed by the developed analytical method. No heavy metals were not found in Shinan Jeungdo salt, but trace amounts of several heavy metals except for cadmium were found in Cheonnam Yongkwang salt.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.7
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• pp.669-676
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• 2004

In this paper, a new algorithm is proposed for resolving multiple broadband incoherent sources incident on a uniform linear array. The proposed method dose not require any initial estimates for finding the transformation matrix, while the Coherent Signal-Subspace Method(CSM) proposed by Wang and Kaveh requires preliminary estimates of multigroup source location. An effective procedure is derived for finding the enhanced spectral density matrix at the center frequency using signal enhancement approach and then constructing a common signal subspace by selecting a unitary transformation matrix which is obtained via rotation of signal subspace method. The proposed approach is found to provide superior performance relative to that obtained with the CSM method in terms of sample bias of direction-of-arrival estimates.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.1
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• pp.20-27
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• 2010

In this paper, we presented a signal model of STAP and actual environment of clutter. The novel estimation method of clutter covariance matrix using median value is proposed to overcome serious performance degradation after NHD in nonhomogeneous clutter. Eigen value characteristic is improved through diagonal loading. Target detection ability and SINR loss of the proposed method though MSMI statistic is also compared with conventional method using average value. The simulation results, confirm the proposed method has better performance than others.