• Smart Structures and Systems
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• v.2 no.1
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• pp.47-60
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• 2006

Bi-spectrum is a tool in the signal processing for identification of non-linear dynamic behvaiour in systems, and well-known for stationary system where components are non-linearly interacting. Breathing of a crack during shaft rotation is also exhibits a non-linear behaviour. The crack is known to generate 2X (twice the machine RPM) and higher harmonics in addition to 1X component in the shaft response during its rotation. Misaligned shaft also shows similar such feature as a crack in a shaft. The bi-spectrum method has now been applied on a small rotating rig to observe its features. The bi-spectrum results are found to be encouraging to distinguish these faults based on few experiments conducted on a small rig. The results are presented here.

• Structural Engineering and Mechanics
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• v.4 no.6
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• pp.601-612
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• 1996

To simulate the large-scale failure evolution with current computational facilities, a simple approach, that catches the essential feature of failure mechanisms, must be available so that the routine use of failure analysis is feasible. Based on the previous research results, a simple analysis procedure is described in this paper for failure simulation. In this procedure, the evolution of localization is represented by a moving surface of discontinuity, and the transition between continuous and discontinuous failure modes are described via the moving jump forms of conservation laws. As a result, local plasticity and damage models, that are formulated based on thermodynamic restrictions, are still valid without invoking higher order terms, and simple integration schemes can be designed for the rate forms of constitutive models. To resolve localized large deformations and subsequent cracking, an efficient structural solution scheme is given for Static and dynamic problems.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.819-822
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• 2000

The merit of the stroke extraction algorithm is the ease of the feature abstraction from the skeleton of a character, But, extracting strokes from Korean characters has two major problems that must be dealt with. One is extracting primitive strokes and the other is merging or splitting the strokes using dynamic information of the strokes. In this paper, a method is proposed to extract strokes from an off-line handwritten Korean character. We have developed some stroke segmentation rules based on splitting, merging and directional analysis. Using these techniques, we can extract and trace the strokes in an off-line handwritten Korean character accurately and efficiently.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.2
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• pp.125-134
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• 2015

Spherical type LNG carrier has many advantages, but has a demerit it is more expensive than membrane type one. Therefore, when calculating the initial estimate of spherical type LNG carrier, high accuracy calculation of tank weight has to be carried out. In this study the simplified analysis method which is able to calculate stresses of all the tank zones is established and has special feature to deal with static and dynamic loading. In order to verify the established method, the design results obtained through the method in this study have been compared with those of existing ship obtained from finite element analysis. As a result, the usability of simplified analysis method has been confirmed.

• Proceedings of the Korean Fiber Society Conference
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• 1997.10a
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• pp.126-130
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• 1997

A series of Thermoplastic polyurethane elastomers was prepared via a two-step polymerization process. The NCO/OH feed ratio of polyurethane synthesized in this study was varied from 1 to 1.3. Studies have been made on the effects of chemical and physical cross-linkina, and the properties of thermoplastic polyurethane elastomers based on isophorone diisocyanate (IPDI)/1,4-butanediol (BD)/poly(propylene glycol) (PPG, MW:2000), isophorone diisocyanate (IPDI)/BD /poly(oxytetramethylene) glycol (PTMG, MW:2000) was compared. These materials were characterized using FTIR spectrometer, dynamic mechanical thermal analyzer, and tensile retraction tester. PTMG based polyurethane elastomers showed higher elasomeric behavior than PPG based polyurethane elastomers at the same NCO/OH ratio. This feature has been connected with the specific nature of the polyols. The permanent set(%) was decreased with increasing maximum elongation from 50% to 300%.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2003.06a
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• pp.114-117
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• 2003

본 논문에서는 video stream내의 움직이는 객체 정보를 추정하고 동적 GTM(genetic tree-map) 알고리즘을 사용하여 얼굴 영역 검출 기법을 제안한다. 기존의 일반적인 객체 추정 기법은 클러스터(cluster)과정을 통하여 영상 정보를 분할하고 그 중 움직이는 객체 부분을 복원함으로서 추정하였다. 제안하는 기법은 BMA(block matching algorithm)［1］ 알고리즘을 사용하여 video stream 에서 움직이는 객체 정보를 얻고 클러스터 알고리즘으로 PCA(principal component analysis)를 사용한다. PCA 기법은 입력 데이터에 관해 통계적 특성을 이용하여 주성분을 찾는다. 주축과 영역분할 알고리즘을 사용하여 데이터를 분할하고, 분할된 객체 정보를 사용하여 특정 객체만을 추정하는 것이 가능하다. 이렇게 추정된 객체를 얼굴영역의 feature에 대하여 신경망 학습인 동적 GTM 알고리즘을 사용하여 생성된 동적 GTM 맵의 정보에 따라 객체의 얼굴영역만을 추출해 낼 수 있다［2-6］.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.12B
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• pp.1051-1059
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• 2003

The key feature of GMPLS is the provision of network resources and the automatic set-up of a path. And the mechanism of protection and restoration of a path is presented when network component fails. This paper suggests CR-LDP Static Detour Mechanism and Dynamic Detour Mechanism. CR-LDP Detours are a mechanism to set up detour paths automatically at every node to protect working path. Hence suggested mechanism performance is compared with existing mechanisms by computer simulation.

• Journal of KIISE:Software and Applications
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• v.31 no.7
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• pp.901-910
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• 2004

In this paper, we propose a content-based MPEG transcoding method using a discontinuity feature in the Discrete Cosine Transform (DCT) domain. A DCT block is transcoded differently depending on the height of dominant discontinuity within a block. In the experiment, we show the result that the video quality of content-based transcoding is better than that of a constant cut-off method and the processing time of the adaptive method is much faster compared with the pixel domain methods in the same bandwidth.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.294-296
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• 1995

In this paper, a vector control method for a AC-Excited BLSM(Brushless Synchronous Motor) is proposed. The BLSM has a feature that separate exciter is not needed for excitation. The proposed method is described in two parts as follow, one is the design of drive and the other is a modeling for its implementation. Rotor flux is estimated using indirect sensing method based on voltage equation in the synchronously rotation reference frame. And rotor position is calculated from rotor angular velocity and stator current. Through computer simulation results of this proposed system, it is shown that the BLSM drive has a ability of precision torque control from the static and dynamic performance.

• Communications for Statistical Applications and Methods
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• v.22 no.5
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• pp.415-434
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• 2015

In this paper we overview the literature on common features analysis of economic time series. Starting from the seminal contributions by Engle and Kozicki (1993) and Vahid and Engle (1993), we present and discuss the various notions that have been proposed to detect and model common cyclical features in macroeconometrics. In particular, we analyze in details the link between common cyclical features and the reduced-rank regression model. We also illustrate similarities and differences between the common features methodology and other popular types of multivariate time series modelling. Finally, we discuss some recent developments in this area, such as the implications of common features for univariate time series models and the analysis of common autocorrelation in medium-large dimensional systems.