• Communications for Statistical Applications and Methods
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• 제6권1호
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• pp.1-10
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• 1999

When the component proportions in mixture experiments are restricted by lower and upper bounds multicollinearity appears all too frequently. The ridge regression can be used to stabilize the coefficient estimates in the fitted model. I propose a graphical method for evaluating the mixture component effects of ridge regression estimator with respect to the prediction variance and the prediction bias.

• 대한의용생체공학회:의공학회지
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• 제30권1호
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• pp.79-88
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• 2009

A harmonic quadrature demodulation method to extract the second harmonic component from focused ultrasound signals after a single transmit-receive event is proposed. In the proposed method, the focused ultrasound signal is converted into baseband inphase and quadrature components by multiplying with sine and cosine signals both having twice the center frequency of the transmitted signal and filtering the two modulated signals. The quadrature component is then passed through a Hilbert filter to be added to the inphase component, which leaves only the envelope of the second harmonic component. A novel phase estimation technique is employed in the proposed method to avoid the phase mismatch between the focused signal and the two modulating signals. The proposed method is verified through both theoretical analysis and computer simulations. It is shown that compared to the pulse inversion scheme the proposed method provides almost the same results for stationary targets and significantly improved harmonic to fundamental ratio for moving targets.

• 한국정보과학회논문지:소프트웨어및응용
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• 제33권3호
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• pp.289-300
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• 2006

제품 라인은 재사용을 위한 연구 방법으로 널리 인식되어 왔다. 제품 라인에서 대표적인 중요 자산은 소프트웨어 컴포넌트이다. 그러나, 제품 라인에 대한 많은 관심에 비해 제품 라인에서 컴포넌트 구조 및 스펙에 대한 연구는 아직 미흡하다. 본 논문은 제품 라인에서 가변성(variability)을 반영한 컴포넌트 구조와 컴포넌트 스펙 방법을 제시한다. 본 논문은 FORM(Feature-Oriented Reuse Method)을 기반으로 제품 라인 컴포넌트의 정적 및 동적 구조, 제품 라인 컴포넌트의 행동 및 동시성 정보를 기술한다. 제품 라인 컴포넌트 스펙에 대한 각 정보는 블랙박스(black-box)와 화이트박스(white-box) 형태로 구분되어 기술되며 각 스펙 정보는 BNF로 정형화된다. 그 스펙들이 제품 라인 컴포넌트의 많은 서로 다른 특징의 충분한 고려를 통해 기술되기 때문에 본 논문은 제품 라인에서 컴포넌트의 손쉬운 개발을 돕고 제품라인 공학 방법론의 적용 방법을 잘 이해하도록 돕는다.

• Journal of the Korean Data and Information Science Society
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• 제24권3호
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• pp.533-541
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• 2013

이 연구에서는 라소를 이용한 간편한 주성분분석을 제안한다. 이 방법은 다음의 두 단계로 구성되어 있다. 먼저 주성분분석에 의해 주성분을 구한다. 다음으로 각 주성분을 반응변수로 하고 원자료를 설명변수로 하는 라소 회귀모형에 의한 회귀계수 추정량을 구한다. 이 회귀계수 추정량에 기반한 새로운 주성분을 사용한다. 이 방법은 라소 회귀분석의 성질에 의해 회귀계수 추정량이 보다 쉽게 0이 될 수 있기 때문에 해석이 쉬운 장점이 있다. 왜냐하면 주성분을 반응변수로 하고 원자료를 설명변수로 하는 회귀모형의 회귀계수가 고유벡터가 되기 때문이다. 라소 회귀모형을 위한 R 패키지를 이용하여 모의생성된 자료와 실제 자료에 이 방법을 적용하여 유용성을 보였다.

• Structural Engineering and Mechanics
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• 제30권5호
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• pp.619-645
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• 2008

This study presents the efficiency of simulating structural systems using a method that combines a simplified component model (SCM) and rigorous component model (RCM). To achieve a realistic simulation of structural systems, a numerical model must be adequately capturing the detailed behaviors of real systems at various scales. However, capturing all details represented within an entire structural system by very fine meshes is practically impossible due to technological limitations on computational engineering. Therefore, this research develops an approach to simulate large-scale structural systems that combines a simplified global model with multiple detailed component models adjusted to various scales. Each correlated multi-scale simulation model is linked to others using a multi-level hierarchical modeling simulation method. Simulations are performed using nonlinear finite element analysis. The proposed method is applied in an analysis of a simple reinforced concrete structure and the Reuipu Elementary School (an existing structure), with analysis results then compared to actual onsite observations. The proposed method obtained results very close to onsite observations, indicating the efficiency of the proposed model in simulating structural system behavior.

• 수면정신생리
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• 제8권1호
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• pp.67-71
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• 2001

Independent Component Analysis (ICA) is a blind source separation method using unsupervised learning and mutual information theory created in the late eighties and developed in the nineties. It has already succeeded in separating eye movement artifacts from human scalp EEG recording. Several characteristic sleep waves such as sleep spindle, K-complex, and positive occipital sharp transient of sleep (POSTS) can be recorded during sleep EEG recording. They are used as stage determining factors of sleep staging and might be reflections of unknown neural sources during sleep. We applied the ICA method to sleep EEG for sleep waves separation. Eighteen channel scalp longitudinal bipolar montage was used for the EEG recording. With the sampling rate of 256Hz, digital EEG data were converted into 18 by n matrix which was used as a original data matrix X. Independent source matrix U (18 by n) was obtained by independent component analysis method ($U=W{\timex}X$, where W is an 18 by 18 matrix obtained by ICA procedures). ICA was applied to the original EEG containing sleep spindle, K-complex, and POSTS. Among the 18 independent components, those containing characteristic shape of sleep waves could be identified. Each independent component was reconstructed into original montage by the product of inverse matrix of W (inv(W)) and U. The reconstructed EEG might be a separation of sleep waves without other components of original EEG matrix X. This result (might) demonstrates that characteristic sleep waves may be separated from original EEG of unknown mixed neural origins by the Independent Component Analysis (ICA) method.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권2호
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• pp.301-314
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• 2015

Aiming at accurately distinguishing modeless component and natural vibration mode terms from data series of nonlinear and non-stationary processes, such as Vortex-Induced Vibration (VIV), a new empirical mode decomposition method has been developed in this paper. The key innovation related to this technique concerns the method to decompose modeless component from non-stationary process, characterized by a predetermined 'maximum intrinsic time window' and cubic spline. The introduction of conceptual modeless component eliminates the requirement of using spurious harmonics to represent nonlinear and non-stationary signals and then makes subsequent modal identification more accurate and meaningful. It neither slacks the vibration power of natural modes nor aggrandizes spurious energy of modeless component. The scale of the maximum intrinsic time window has been well designed, avoiding energy aliasing in data processing. Finally, it has been applied to analyze data series of vortex-induced vibration processes. Taking advantage of this newly introduced empirical decomposition method and mode identification technique, the vibration analysis about vortex-induced vibration becomes more meaningful.

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2319-2328
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• 2018

This paper introduces a control method for a transformerless MMC-HVDC system. The proposed method can effectively control the grid currents of the MMC-HVDC system under unbalanced grid conditions such as a single line-to-ground fault. The proposed method controls the currents of the positive sequence component and the negative sequence component without separating algorithms. Therefore, complicated calculations for extracting the positive sequence and the negative sequence component are not required. In addition, a control method to regulate a zero sequence component current under unbalanced grid conditions in the transformerless MMC-HVDC system is also proposed. The validity of the proposed method is verified through PSCAD/EMTDC simulation.

• 반도체디스플레이기술학회지
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• 제21권1호
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• pp.22-26
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• 2022

This paper proposes a new method for the recognition of road surface marks and numbers. The proposed method designates a region of interest on the road surface without first detecting a lane. The road surface markings are extracted by location and size using a connection component analysis. Distortion due to the perspective effect is minimized by normalizing the size of the road markings. The road surface marking of the connected component is recognized by matching it with the stored road marking templates. The proposed method is implemented using C language in Raspberry Pi 4 system with a camera module for a real-time image processing. The system was fixedly installed in a moving vehicle, and it recorded a video like a vehicle black box. Each frame of the recorded video was extracted, and then the proposed method was tested. The results show that the proposed method is successful for the recognition of road surface marks and numbers.

• 한국정보과학회논문지:소프트웨어및응용
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• 제30권9호
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• pp.812-820
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• 2003

복잡한 응용 프로그램의 빠른 개발과 이의 용이한 유지 보수를 지원하기 위하여 재사용 가능 한 컴포넌트 기반 개발(CBD: Component-Based Development) 개념이 확산되고 있다. 이와 관련되어 EJB, COM, CCM 등과 같은 컴포넌트 모델에 대한 연구가 다양하게 진행되고 있으나, 컴포넌트의 궁극적 목표인 재사용 극대화의 입장에서, 아직까지 이미 개발된 컴포넌트들의 유연한 조립은 지원하지 못한다. 이를 해결하기 위해서는 제삼자에 의해 제공된 이질적인 컴포넌트들을 유연하게 재구성 및 조림할 수 있는 상위 레벨의 아키텍처가 필요하며 그러한 아키텍처를 기반으로 구현된 컴포넌트들이 조립되어야 한다. 본 논문은 제삼자에 의해 제공된 이질적인 컴포넌트들을 플러그 앤 플레이 방식으로 유연하게 재구성 및 조립할 수 있도록 아키텍처 기반의 컴포넌트 조립 시스템 설계 및 구현 방법을 제안하고 이를 지원하는 CASE 도구인 Cobalt Assembler를 소개한다.