• Earthquakes and Structures
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• 제2권4호
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• pp.323-336
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• 2011

The problem of reconstruction of complete building response from a limited number of response measurements is considered. The response at the intermediate degrees of freedom is reconstructed by using piecewise cubic Hermite polynomial interpolation in time domain. The piecewise cubic Hermite polynomial interpolation is preferred over the spline interpolation due to its trend preserving character. It has been shown that factorization of response data in variable separable form via singular value decomposition can be used to derive the complete set of normal modes of the structural system. The time domain principal components can be used to derive empirical transfer functions from which the natural frequencies of the structural system can be identified by peak-picking technique. A reduced-rank approximation for the system flexibility matrix can be readily constructed from the identified mass-orthonormal mode shapes and natural frequencies.

• Structural Engineering and Mechanics
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• 제42권2호
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• pp.191-210
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• 2012

The Force Density Method (FDM) is a well known and extremely versatile tool in form finding of cable nets. In its linear formulation such method makes it possible to find all the possible equilibrium configurations of a net of cables having a certain given connectivity and given boundary conditions on the nodes. Each singular configuration corresponds to an assumed force density distribution. Its improvement as Non-Linear Force Density Method (NLFDM) introduces the possibility of imposing assigned relative distances among the nodes, the tensile level in the elements and/or their initial undeformed length. In this paper an Extended Force Density Method (EFDM) is proposed, which makes it possible to set conditions in terms of given fixed nodal reactions or, in other words, to fix the positions of a certain number of nodes and, at the same time, to impose the intensity of the reaction force. Through such extension, the (EFDM) enables us to deal with form findings problems of cable nets subjected to given constraints and, in particular, with mixed structures, made of cables and struts. The efficiency and the robustness of method are assessed through comparisons with other form finding techniques in dealing with characteristic applications to the prestress design of cable systems. As a further extension, the EFDM is applied to structures having some parts not yet geometrically defined, as can happen in designing new creative forms.

• Journal of Information Processing Systems
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• 제12권1호
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• pp.46-56
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• 2016

Dynamic textures are videos that exhibit a stationary property with respect to time (i.e., they have patterns that repeat themselves over a large number of frames). These patterns can easily be tracked by a linear dynamic system. In this paper, a model that identifies the underlying linear dynamic system using wavelet coefficients, rather than a raw sequence, is proposed. Content based threshold filtering based on Set Partitioning in a Hierarchical Tree (SPIHT) helps to get another representation of the same frames that only have low frequency components. The main idea of this paper is to apply SPIHT based threshold filtering on different bands of wavelet transform so as to have more significant information in fewer parameters for singular value decomposition (SVD). In this case, more flexibility is given for the component selection, as SVD is independently applied to the different bands of frames of a dynamic texture. To minimize the time complexity, the proposed model is implemented on a graphics processing unit (GPU). Test results show that the proposed dynamic system, along with a discrete wavelet and SPIHT, achieve a highly compact model with better visual quality, than the available LDS, Fourier descriptor model, and higher-order SVD (HOSVD).

• 대한기계학회논문집
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• 제3권3호
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• pp.91-97
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• 1979

Boundary layer equations (partial differential equations) can be transformed to ordinary diffential equations with constant coeffieients in terms of similarity transformed to ordinary differential equations with constant coeffieients in terms of similarity transformations in the heat tranfer analysis on the surface of any axiaymmetric boiles. The azimuth functions can not be uniquely determined because of the singular behavior at the stagnation point(X=0.deg.).In spite of the azimuth functions behaving singularly, many of researchers have analyzed the heat transfer problem on a horizontal chlinder or a sphere, supposing the set of solutions( $H_{1}$ & G$_{1}$) of being yieled from the simple differential equation to be unique solution of therazimuth functions. In order to ascertain whether mathematical incompatibility as mentioned above can be admitted in the viewpoint of enginerring or not, condensation heat transfer coefficients on a sphere are computed for all azimuth functions( $H_{1}$ G$_{1}$ & $H_{2}$ G$_{2}$) and comparisons with the experimental result are discussed.

• 품질경영학회지
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• 제23권4호
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• pp.28-41
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• 1995

We consider the problem of identifying multiple outliers in linear model. The available regression diagnostic methods often do not succeed in detecting multiple outliers because of the masking and swamping effect. Recently, among the various robust estimator of reducing the effect of outliers, LMS(Least Meadian Square) estimator has been to be a suitable method proposed to expose outliers and leverage points. However, as you know it, the data analysis method with LMS estimator is to be taken the median of the squared residuals in the sample which is extracted the sample space. Then this model causes the trouble, for the number of the chosen sample is nCp, i.e. as the size of sample space n is increasing, the number is increasing fastly. And the covariance matrix may be the singular matrix, so that matrix is approching collinearity. Thus we propose a procedure ELMS for the resampling in LMS method and study the size of the effective elementary set in this algorithm.

• 제어로봇시스템학회논문지
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• 제8권7호
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• pp.539-546
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• 2002

This paper presents a new direct seek control scheme that provides fast data access capability and robust performance for high-speed rotational optical disk drives (ODD). When a disk is rotating at a high speed to obtain fast data transfer in ODD, the magnitude and frequency of velocity disturbance caused by eccentric rotation of the disk increase in proportion to the rotational speed of the disk. Such disturbances make it almost impossible for the conventional seek control scheme to achieve stable and satisfactory seek performance. We analyze the problems that may arise when the conventional seek control scheme is applied to the high-speed rotational ODD and propose a new direct seek control scheme that will solve such problems. In the proposed scheme, a seek control system is designed such that its performance is guaranteed for a set of plants with parameter perturbations. The performance of the proposed seek control scheme is shown by experiments using a high-speed rotational ODD.

• 정보학연구
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• 제7권2호
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• pp.43-54
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• 2004

홉필드 네트웍(Hopfield Network)은 존 홉필드(John J. Hopfield) 박사에 의해 제안된 이래 패턴인식과 최적화 문제에 활용되어 왔다. 특히 리(Jian-Hua Li)에 의해 제안된 방식은 SVD(singular value decomposition) 기법을 사용하여 입력패턴을 재구성함으로써 효율향상에 기여하였다. 본 논문은 리(Li)가 제안한 홉필드 네트웍에 사용할 패턴 집합의 선형 선처리 방식에 따른 성능 향상을 실험하였다. 선형 선처리 방식에 하다마드 방식과 랜덤 방식이 최대 30%, 하다마드 방식이 최대 15%의 성능이 향상되었다. 수렴시간 측면에서 보면 랜덤 방식이 최대 5 이터레이션, 하다마드 방식이 최대 2.5 이터레이션의 성능 향상을 확인하였다.

• 대한기계학회논문집A
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• 제33권10호
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• pp.1029-1037
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• 2009

Recently, the technologies of mobile robots have been growing rapidly in the fields such as cleaning robot, explosive ordnance disposal robot, patrol robot, etc. However, the researches about the autonomous underwater robots have not been done so much, and they still remain at the low level of technology. This paper describes a model of 3-joint (4 links) fish robot type. Then we calculate the dynamic motion equation of this fish robot and use Singular Value Decomposition (SVD) method to reduce the divergence of fish robot's motion when it operates in the underwater environment. And also, we analysis response characteristic of fish robot according to the parameters of input torque function and compare characteristic of fish robot with 3 joint and fish robot with 2 joint. Next, fish robot's maximum velocity is optimized by using the combination of Hill Climbing Algorithm (HCA) and Genetic Algorithm (GA). HCA is used to generate the good initial population for GA and then use GA is used to find the optimal parameters set that give maximum propulsion power in order to make fish robot swim at the fastest velocity.

• 한국지능시스템학회논문지
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• 제13권1호
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• pp.57-62
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• 2003

자동화 지문인식을 위한 과정에서 지문영상의 정보를 보존하면서 최적의 세선화와 특이점추출을 위한 중요한 부분은 이진화 과정이다. 이진화 과정은 그레이-스케일 레벨의 영상을 0과 255값으로 바꾸는 과정이다. 이 과정에서 적절한 기준레벨값(Threshold Value)을 설정해 주지 않으면 지문영상의 정보가 손실된다. 본 논문에서는 이진화 과정 부분에 인공지능 기법을 적용하여 입력되는 지문영상에서 실시간으로 기준레벨(Threshold)을 추출하는 방법을 제안한다. 실험결과 기존의 방법과 비교하여 좋은 성능을 보여주고 있음을 나타낸다

• Journal of Contemporary Eastern Asia
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• 제13권2호
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• pp.41-56
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• 2014

This research paper advances our understanding of complex interdependence among countries. Existing research has found that total factor productivity (TFP), the residual from the economic growth function, is hindered in the absence of a country's strong political and legal institutions or if a country does not already have a sufficiently high level of TFP. We also know that regional efforts to eliminate pollution are complex. Bridging these two areas while focusing on a high polluting yet high innovating region, the following research questions are posed: Are Northeast Asian countries key collaborators in pursuit of green R&D? Are Northeast Asian countries collaborating extensively with each other? What are the implications for other regions' attempts to establish these kinds of relations? To answer the above questions, biofuels-related technology as defined in the International Patent Classification's "green inventory" of environmentally sound technologies is examined. Patent data is drawn from the USPTO and inventors' country origin as the unit of analysis. For the 1990-2013 period, the Northeast Asian countries are in the core of a small set of collaborating countries. There is evidence that their centrality has increased in recent years. Most importantly, East Asia is becoming a singular research hub in terms of biofuels-related R&D, offering a counter in the foreseeable future to the dominance of the American and European research network hubs.