• 방송공학회논문지
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• 제7권2호
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• pp.168-180
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• 2002

This paper proposes a novel method to detect unauthorized copies of digital images. This copy detection scheme can be used as either an alternative approach or a complementary approach to watermarking. A test image is reduced to 8$\times$8 sub-image by intensity averaging, and the AC coefficients of its discrete cosine transform (DCT) are used to compute distance from those generated from the query image, of which a user wants to find copies. Copies may be Processed to avoid copy detection or enhance image quality. We show ordinal measure of DCT coefficients, which is based on relative ordering of AC magnitude values and using distance metrics between two rank permutations, are robust to various modifications of the original image. The optimal threshold selection scheme using the maximum a posteriori (MAP) criterion is also addressed.

• 수산해양기술연구
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• 제35권4호
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• pp.435-447
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• 1999

It is main objective of this approach to present a method to analyse stochastic design sensitivity for problems of structural dynamics with randomness in design parameters. A combination of the adjoint variable approach and the second order perturbation method is used in the finite element approach. An alternative form of the constant functional that holds for all times is introduced to consider the time response of dynamic sensitivity. The terminal problem of the adjoint system is solved using equivalent homogeneous equations excited by initial velocities. The numerical procedures are shown to be much more efficient when based on the fold superposition method: the generalized co-ordinates are normalized and the correlated random variables are transformed to uncorrelated variables, whereas the secularities are eliminated by the fast Fourier transform of complex valued sequences. Numerical algorithms have been worked out and proved to be accurate and efficient : they can be readily adapted to fit into the existing finite element codes whose element derivative matrices can be explicitly generated. The numerical results of two cases -2 dimensional portal frame for the comparison with reference and 3-dimensional frame structure - for the deterministic sensitivity analysis are presented.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.346-353
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• 2002

The steam generator feedwater flow rate in a nuclear power plant was estimated by means of artificial neural networks with the wavelet analysis for enhanced information extraction. The fouling of venturi meters, used for steam generator feedwater flow rate in pressurized water reactors, may result in unnecessary plant power derating. The backpropagation network was used to generate models of signals for a pressurized water reactor. Multiple-input single-output heteroassociative networks were used for evaluating the feedwater flow rate as a function of a set of related variables. The wavelet was used as a low pass filter eliminating the noise from the raw signals. The results have shown that possible fouling of venturi can be detected by neural networks, and the feedwater flow rate can be predicted as an alternative to existing methods. The research has also indicated that the decomposition of signals by wavelet transform is a powerful approach to signal analysis for denoising.

• Ocean and Polar Research
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• 제28권4호
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• pp.425-438
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• 2006

This study has the purpose of providing a framework for analyzing problems of institutional choice, illustrating the complex configuration of variables that must be addressed when individuals in field settings attempt to fashion rules to improve their individual and joint outcomes. The reason for presenting this complex array of variables (i.e., situational variables) as a framework rather than as a model is precisely because one cannot encompass this degree of complexity within a single model. The results of this study imply that it is important for researchers and government officials to understand that appropriators have a certain amount of ability to transform the status quo rules to the alternative rules.

• 한국콘텐츠학회논문지
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• 제7권5호
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• pp.10-15
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• 2007

본 논문에서는 기존의 컴퓨터비전 기술을 이용한 생물체의 자동 추적 시스템을 통하여 얻어진 움직임 데이터를 이용하여 일반적인 움직임의 범위를 벗어나는 비정상적인 움직임 제적을 탐지하여 주는 방법을 제안하고 있다. 또한 웨이블릿 변환을 통한 부대역간 주파수 성분의 특성을 이용하여 움직임 궤적의 분석에 적용하는 방법을 제시하고 있다. 실험 결과를 통하여 인위적인 약물 처리 전 후에 탐지되는 활동성을 표현하는 특징점의 수가 통계학적으로 유의함을 확인하였다.

• 대한두개안면성형외과학회지
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• 제21권4호
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• pp.211-218
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• 2020

Autologous fat grafts are widely used in soft-tissue augmentation and reconstruction. To reduce the unpredictability of fat grafts and to improve their long-term survival, cell-assisted lipotransfer (CAL) was introduced. In this alternative method, autologous fat is mixed and grafted with stromal vascular fraction cells or adipose-derived stem/stromal cells (ASCs). In regenerative medicine, ASCs exhibit excellent therapeutic potential and are also simple to harvest. Although the efficacy of CAL has been demonstrated in experimental and clinical research, studies on its safety in terms of oncologic risk have reported inconclusive results. In order to establish CAL as a viable stem cell therapeutic approach, it will be necessary to demonstrate its oncologic safety in basic and clinical studies. Doing so could transform the paradigm of clinical strategy and practice for the treatment of a wide variety of diseases.

• Carbon letters
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• 제13권2호
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• pp.61-72
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• 2012

Dye removal from waste water via adsorption by activated carbons (ACs) developed from agricultural wastes represents an ideal alternative to other expensive treatment options. Physical and chemical ACs were prepared from rice husks. The textural properties of the ACs were characterized by Brunauer-Emmett-Teller-$N_2$ adsorption and scanning electron microscopy. The chemistry of the carbon surface was investigated by Fourier transform infrared spectroscopy, base and acid neutralization capacities, pH of the active carbon slurry, and $pH_{pzc}$. The adsorption capacities of the ACs for the basic dye (methylene blue) and acid dye (acid green 25) were determined using parameters such as contact time, pH, and temperature. NaOH-ACs showed the highest surface area and total pore volume, whereas steam-ACs showed the lowest ones.

• Journal of Advanced Marine Engineering and Technology
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• 제33권4호
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• pp.497-501
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• 2009

When modal tests on the large structures and machinery are performed, it is in general difficult and inaccurate to use artificial excitation devices such as impact hammers, because of insufficient capacity of the device and different environmental conditions of the concerned structures. Therefore, the Operational Modal Analysis(OMA) technique, which is performed by measuring only vibration responses during the operation of the objective product, can be one alternative. In this paper, the way to identify natural frequencies, mode shapes and damping ratios of a ship by using the OMA during the sea trail is described.

• Journal of the Optical Society of Korea
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• 제16권2호
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• pp.91-94
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• 2012

Arrayed waveguide grating (AWG) phase errors are normally assessed from the Fourier transform of the interference intensity data in the frequency domain method. However it is possible to identify the phases directly from the intensity data if one adopts a trial-and-error method. Since the functional form of the intensity profile is known, the intensities can be calculated theoretically by assuming arbitrary phase errors. Then we decide the phases that give the best fit to the experimental data. We verified this method by a simulation. We calculated the intensities for an artificial AWG which is given arbitrary phases and amplitudes. Then we extracted the phases and amplitudes from the intensity data by using our trial-and-error method. The extracted values are in good agreement with the originally given values. This approach yields better results than the analysis using Fourier transforms.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.731-732
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• 2006

Limitations on the Linear Discriminant Analysis (LDA) for face recognition, such as the loss of generalization and the computational infeasibility, are addressed and illustrated for small number of samples. The Principal Component Analysis (PCA) followed by the LDA mapping may be an alternative that can overcome this limitation. We also show that processing time is reduced by wavelet transform.