• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2001.12a
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• pp.189-192
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• 2001

뇌 기능의 연구수단으로써 널리 사용되고 있는 뇌파(Electroencephalogram)는 측정시에 노이즈(noise)나 잡파(Artifacts)가 섞여서 측정되기 쉽다. 이러한 노이즈나 잡파들을 제거하기 위하여 미지의 혼합된 신호들을 분리하는데 적용되고 있는 통계적인 처리 방식인 독립성분분석(ICA) 알고리즘을 뇌파에 적용하여 그 결과를 알아보았다. 본 연구에서는 정상인의 안구운동(Eye Movement)상태의 뇌파 신호에 대해서 독립성분분석을 적용하여 안구운동과 관련된 잡파가 포함된 원래의 뇌파신호(Original EEG Signal)와 제거한 다음의 뇌파신호(Corrected EEG Signal)에 대하여 비선형 분석법을 사용하여 두 신호의 유의한 차이점을 밝히고, 분리된 독립 신호들의 해부학적 발생위치 및 분포를 추정하였다.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.4
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• pp.258-262
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• 2017

The PCA(Principal Component Analysis) algorithm is widely used as a technique of expressing the eigenvectors of the covariance matrix that best represents the characteristics of the data and reducing the high dimensional vector to a low dimensional vector. In this paper, we have developed a personal authentication method based on ECG using principal component analysis. The proposed method showed excellent recognition performance of 98.2 [%] when it was experimented using electrocardiogram data obtained at weekly intervals. Therefore, it can be seen that it is useful for personal authentication by reducing the dimension without changing the information on the variability and the correlation set variable existing in the electrocardiogram data by using the principal component analysis technique.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.792-795
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• 2007

To quantify irregular body motions the time series analysis was applied to the gait study. The motions obtained from gait experiment are complex to exhibit nonlinear behaviors. The purpose of this study is to measure quantitatively the characteristics of the major six joints of the body during walking. The gait experiments were carried out for eighteen young males walking on a motor driven treadmill. Joint motions were captured using eight video cameras, and then three dimensional kinematics of the neck and the upper and lower extremities were computed by KWON 3D motion analysis software. The largest Lyapunov exponent was calculated from the time series to quantify stabilities of each joint. The results provides a data set of nonlinear dynamic characteristics for six joints engaged in normal walking.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.11
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• pp.205-208
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• 1995

Analysis of Heart Rate Variability has been studied to estimate autonomic nervous system. PR interval represents conduction time from atrium to ventricle. PR interval variability(PRV) is also can be used to estimate autonomic nervous system. We have acquired two-state ECGs of children who are before vagal stimulation and after vagal stimulation. We applied chaotic theory to each ECG in order to analyze PRV, and compared the results from frequency domain analysis. The correlation dimension of PRV of pre-stimulated children is higher than that of post-stimulated children.

• Solar Energy
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• v.19 no.2
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• pp.29-36
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• 1999

Heat transfer characteristics of a low temperature latent heat storage system during the heat storage stage was examined for the circular finned tubes using fatty acid which shows the big density difference during melting as phase change materials. The heat storage vessel has the dimension of 530 mm height, 74 mm inside diameter and inner heat transfer tube is 480 mm in height and 13.5 mm outside diameter. Hot water was employed as the heat transfer fluid. During the heat storage stage, it was found that both conduction and natural convection were the major heat transfer mechanism. It was also found that the effect of natural convection on the heat transfer was more significant for the unfinned tube system than that for the finned tube system. The experimentally determined overall heat transfer coefficients were in the range of $50{\sim}250W/m^2K$ and the correlation for natural convection heat transfer as a function of Nusselt and Rayleigh number was proposed.

• Journal of Korean Society for Quality Management
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• v.42 no.4
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• pp.607-616
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• 2014

Purpose: This paper reviews popular measurement system indices and proposes a procedure for assessing a measurement system using two parameters with intraclass correlation and a factor for process capability. Methods: Gage Repeatability and Reproducibility(GR&R), precision-to-tolerance ratio(PTR), number of distinct categories, producer's and consumer's risks are employed to assess the measurement capabilities and discuss the relationships between measurement system metrics. Results: Two-dimensional plot by two parameters is presented to assess adequacy of the measurement system and process capability. A numerical example and previously studied case study are provided for illustration. Conclusion: The procedure proposed in this paper using two-dimension parameters provides a valuable procedure and helpful guidelines to quality and production managers in assessing the capabilities of a measurement system and choosing the needed actions to be the most benefit.

• Speech Sciences
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• v.12 no.2
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• pp.171-182
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• 2005

An efficient GMM (Gaussian mixture modeling) method based on LPCA (local principal component analysis) with VQ (vector quantization) for speaker identification is proposed. To reduce the dimension and correlation of the feature vector, this paper proposes a speaker identification method based on principal component analysis. The proposed method firstly partitions the data space into several disjoint regions by VQ, and then performs PCA in each region. Finally, the GMM for the speaker is obtained from the transformed feature vectors in each region. Compared to the conventional GMM method with diagonal covariance matrix, the proposed method requires less storage and complexity while maintaining the same performance requires less storage and shows faster results.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.1 no.1
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• pp.104-112
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• 2001

Simply, Nonlinear dynamics theory means the complicated and noise-like phenomena originated form nonlinearity involved in deterministic dynamical system. An almost all the natural signals have nonlinear property. However, there exist few analysis software tool or package for a research and development of applications. We develop nonlinear time series analysis simulator is to provide a common and useful tool for this purpose and to promote research and development of nonlinear dynamics theory. This simulator is consists of the following four modules such as generation module, preprocessing module, analysis module and ICA module. In this paper, we applied to Electroencephalograph (EEG), as it turned out, our simulator is able to analyze nonlinear time series. Besides, we could get the useful results using the various parameters. These results are used to diagnostic the brain diseases.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.396-398
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• 2009

Scoliosis is a three-dimensional deformity caused by lateral curvature of the spine. The existing braces used to correct the posture were some drawbacks such as inconvenience, tightness as well as unfitness to wear. In this study, we devised a posture guidance system in order to monitor a posture continuously and lead to pose correctly and a new method fur measuring a Cobb's angle value in third dimension based on two 3-axis accelerometers. As a result, the correlation coefficients between desired and measured angles were and standard error between desired and measured angles were 0.99, 1.32(x-axis), 0.99 and 1.10(y-axis), respectively. The devised system showed good potential for the optimal posture guide and an early detection of scoliosis.

• Journal of the Korean Home Economics Association
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• v.40 no.1
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• pp.135-146
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• 2002

The Purpose of this study was to identify the sensibility elements and the evaluative dimensions of internet fashion shopping mall to supply optimal experience to the customer. First, association words for internet fashion shopping mall by open-ended method and sensibility-expression-adjective feeling as navigating personally 57 shopping mall dealing with fashion products were collected. Collected adjectives were ranked after making index by frequency and diversity. Then, correlation analysis was executed to extract independent adjective and their opposite words. Semantic differential scale was made for internet-fashion-shopping-mall-evaluation. After preliminary investigation with this scale, factor analysis was implemented. 12 sensibility evaluation words were extracted. Then, 200 subjects evaluated satisfaction degree for 8 selected shopping mall. To explain the hierarchy of internet fashion shopping mall, cluster analysis was applied. The understanding of sensibility element and evaluative dimensions of internet fashion shopping mall can be utilized efficiently as basic materials when marketer plans internet shopping mall design and makes marketing strategy.