• 제목/요약/키워드: fundamental structure

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온톨로지 구축을 위한 인간의 지식구조 분석: 문헌정보학 영역을 중심으로 (Human Knowledge Structure Analysis for Designing Ontologies: Using Library and Information Science Field)

  • 곽철완
    • 한국도서관정보학회지
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    • 제36권1호
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    • pp.459-477
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    • 2005
  • 본 연구의 목적은 인간들이 공통적으로 공유하는 지식구조를 기반으로 온톨로지를 구축하기 위해 인간들이 가지고 있는 개념들의 범주와 관계를 조사하여 기본모델을 제시하고자 하는데 있다. 연구방법은 1차 조사에는 설문지법을 이용하였고 2차 조사에는 면담법을 사용하였다. 연구 결과 문헌정보학에 대한 KDC나 DDC의 구조와 학생들이 가지고 있는 지식구조에는 차이가 있었다. 학생들이 가지고 있는 구조의 기본 틀은 개체중심의 관계성으로 이루어져 있었다. 조사결과 4가지의 관계성 모델이 축출되었는데, 이 모델은 문헌정보학 분야 온톨로지 구축에 기초 자료로 활용할 수 있을 것이다. 그리고 학업성적이 지식구조에 영향을 미치고 있는 것으로 밝혀졌다.

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Vibrations of wind-turbines considering soil-structure interaction

  • Adhikari, S.;Bhattacharya, S.
    • Wind and Structures
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    • 제14권2호
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    • pp.85-112
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    • 2011
  • Wind turbine structures are long slender columns with a rotor and blade assembly placed on the top. These slender structures vibrate due to dynamic environmental forces and its own dynamics. Analysis of the dynamic behavior of wind turbines is fundamental to the stability, performance, operation and safety of these systems. In this paper a simplied approach is outlined for free vibration analysis of these long, slender structures taking the soil-structure interaction into account. The analytical method is based on an Euler-Bernoulli beam-column with elastic end supports. The elastic end-supports are considered to model the flexible nature of the interaction of these systems with soil. A closed-form approximate expression has been derived for the first natural frequency of the system. This new expression is a function of geometric and elastic properties of wind turbine tower and properties of the foundation including soil. The proposed simple expression has been independently validated using an exact numerical method, laboratory based experimental measurement and field measurement of a real wind turbine structure. The results obtained in the paper shows that the proposed expression can be used for a quick assessment of the fundamental frequency of a wind turbine taking the soil-structure interaction into account.

Addressing the Challenges of Describing Alternative Format Materials: A Metadata Framework to Enhance Information Accessibility of People with Disabilities

  • Lee, Seungmin
    • Journal of Information Science Theory and Practice
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    • 제9권4호
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    • pp.1-14
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    • 2021
  • Library communities face many problems and limitations in describing alternative format materials based on the traditional MAchine Readable Cataloging (MARC) structure. To address these problems, this research proposes an XML-based descriptive metadata framework that establishes general but fundamental bibliographic aspects of various alternative format materials by providing core elements that are essential in describing these materials. Different from existing bibliographic structures, the proposed metadata framework can represent a fundamental descriptive structure by establishing four upper-level categories, 17 core elements, and 10 sub-elements in a hierarchical structure optimized to alternative format materials. By using this principal descriptive structure, the proposed metadata framework can guide different institutions in the creation of bibliographic records for these materials in a consistent way. It is also expected to address the difficulties in describing alternative format materials in library communities and enhance the information accessibility of individuals with various types of disabilities. In addition, the proposed metadata framework is an alternative approach which functions as a mediator between heterogeneous characteristics of alternative format materials and the existing bibliographic structures in library communities.

SEMI-INVARIANT SUBMANIFOLDS OF CODIMENSION 3 IN A COMPLEX SPACE FORM WITH 𝜉-PARALLEL STRUCTURE JACOBI OPERATOR

  • U-Hang KI;Hyunjung SONG
    • East Asian mathematical journal
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    • 제40권1호
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    • pp.1-23
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    • 2024
  • Let M be a semi-invariant submanifold of codimension 3 with almost contact metric structure (𝜙, 𝜉, 𝜂, g) in a complex space form Mn+1(c). We denote by A, K and L the second fundamental forms with respect to the unit normal vector C, D and E respectively, where C is the distinguished normal vector, and by R𝜉 = R(𝜉, ·)𝜉 the structure Jacobi operator. Suppose that the third fundamental form t satisfies dt(X, Y) = 2𝜃g(𝜙X, Y) for a scalar 𝜃(≠ 2c) and any vector fields X and Y , and at the same time R𝜉K = KR𝜉 and ∇𝜙𝜉𝜉R𝜉 = 0. In this paper, we prove that if it satisfies ∇𝜉R𝜉 = 0 on M, then M is a real hypersurface of type (A) in Mn(c) provided that the scalar curvature $\bar{r}$ of M holds $\bar{r}-2(n-1)c{\leq}0$.

VIBRATION SIGNAL ANALYSIS OF MAIN COOLANT PUMP FLYWHEEL BASED ON HILBERT-HUANG TRANSFORM

  • LIU, MEIRU;XIA, HONG;SUN, LIN;LI, BIN;YANG, YANG
    • Nuclear Engineering and Technology
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    • 제47권2호
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    • pp.219-225
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    • 2015
  • In this paper, a three-dimensional model for the dynamic analysis of a flywheel based on the finite element method is presented. The static structure analysis for the model provides stress and strain distribution cloud charts. The modal analysis provides the basis of dynamic analysis due to its ability to obtain the natural frequencies and the vibration-made vectors of the first 10 orders. The results show the main faults are attrition and cracks, while also indicating the locations and patterns of faults. The harmonic response simulation was performed to gain the vibration response of the flywheel under operation. In this paper, we present a Hilbert-Huang transform (HHT) algorithm for flywheel vibration analysis. The simulation indicated that the proposed flywheel vibration signal analysis method performs well, which means that the method can lay the foundation for the detection and diagnosis in a reactor main coolant pump.

Estimation of fundamental period of reinforced concrete shear wall buildings using self organization feature map

  • Nikoo, Mehdi;Hadzima-Nyarko, Marijana;Khademi, Faezehossadat;Mohasseb, Sassan
    • Structural Engineering and Mechanics
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    • 제63권2호
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    • pp.237-249
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    • 2017
  • The Self-Organization Feature Map as an unsupervised network is very widely used these days in engineering science. The applied network in this paper is the Self Organization Feature Map with constant weights which includes Kohonen Network. In this research, Reinforced Concrete Shear Wall buildings with different stories and heights are analyzed and a database consisting of measured fundamental periods and characteristics of 78 RC SW buildings is created. The input parameters of these buildings include number of stories, height, length, width, whereas the output parameter is the fundamental period. In addition, using Genetic Algorithm, the structure of the Self-Organization Feature Map algorithm is optimized with respect to the numbers of layers, numbers of nodes in hidden layers, type of transfer function and learning. Evaluation of the SOFM model was performed by comparing the obtained values to the measured values and values calculated by expressions given in building codes. Results show that the Self-Organization Feature Map, which is optimized by using Genetic Algorithm, has a higher capacity, flexibility and accuracy in predicting the fundamental period.

An approximate formula to calculate the fundamental period of a fixed-free mass-spring system with varying mass and stiffness

  • Kim, Juwhan;CoIIins, Kevin R.;Lim, Yun Mook
    • Structural Engineering and Mechanics
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    • 제25권6호
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    • pp.717-732
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    • 2007
  • A formula to approximate the fundamental period of a fixed-free mass-spring system with varying mass and varying stiffness is formulated. The formula is derived mainly by taking the dominant parts from the general form of the characteristic polynomial, and adjusting the initial approximation by a coefficient derived from the exact solution of a uniform case. The formula is tested for a large number of randomly generated structures, and the results show that the approximated fundamental periods are within the error range of 4% with 90% of confidence. Also, the error is shown to be normally distributed with zero mean, and the width of the distribution (as measured by the standard deviation) tends to decrease as the total number of discretized elements in the system increases. Other possible extensions of the formula are discussed, including an extension to a continuous cantilever structure with distributed mass and stiffness. The suggested formula provides an efficient way to estimate the fundamental period of building structures and other systems that can be modeled as mass-spring systems.

Railway Governance and Power Structure in China

  • Lee, Jinjing
    • International Journal of Railway
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    • 제1권4호
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    • pp.129-133
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    • 2008
  • Over the last $15{\sim}20$years, many countries have adopted policies of railway privatization to keep up with increasing competition from road and air transport. Although each country and case has its own history, market characteristics, political context as well as administrative process, railway privatizations (including railway restructure, concession etc.) in the west usually are accompanied with the establishment of new regulatory regimes. Therefore, railway governance has been innovating towards an interaction of government, regulator, industry bodies, user groups, trade unions and other interested groups within the regulatory framework. However, it is not the case in China. Although China had seen a partial privatization in some branch lines and is experiencing a much larger-scale privatization by establishing joint-ventures to build and operate high-speed passenger lines and implementing an asset-based securitization program, administrative control still occupies absolutely dominant position in the railway governance in China. Ministry of Railway (MOR) acts as the administrator, operator as well as regulator. There is no national policy that clearly positions railway in the transportation network and clarifies the role of government in railway development. There is also little participation from interested groups in the railway policy making, pricing, service standard or safety matter. Railway in China is solely governed by the mere executive agency. Efficiency-focused economic perspective explanation is far from satisfaction. A wider research perspective from political and social regime is of great potential to better explain and solve the problem. In the west, separation and constrains of power had long been established as a fundamental rule. In addition to internal separation of political power(legislation, execution and jurisdiction), rise of corporation in the 19th century and association revolution in the 20th century greatly fostered the growth of economic and social power. Therefore, political, social and economic organizations cooperate and compete with each other, which leads to a balanced and resonable power structure. While in China, political power, mainly party-controlled administrative power has been keeping a dominated position since the time of plan economy. Although the economic reform promoted the growth of economic power of enterprises, it is still not strong enough to compete with political power. Furthermore, under rigid political control, social organizations usually are affiliated to government, independent social power is still too weak to function. So, duo to the limited and slow reform in political and social regime in China, there is an unbalanced power structure within which political power is dominant, economic power expanding while social power still absent. Totally different power structure in China determines the fundamental institutional environment of her railway privatization and governance. It is expected that the exploration of who act behind railway governance and their acting strength (a power theory) will present us a better picture of railway governance as a relevant transportation mode. The paper first examines the railway governance in China and preliminarily establishes a linkage between railway governance and its fundamental institutional environment, i.e. power structure in a specific country. Secondly, the reason why there is no national policy in China is explored in the view of political power. In China, legislative power is more symbolic while party-controlled administrative power dominates political process and plays a fundamental role in Chinese railway governance. And then, in the part three railway finance reform is analyzed in the view of economic power, esp. the relationship of political power and economic power.

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INFRA-NILMANIFOLDS AND THEIR FUNDAMENTAL GROUPS

  • Dekimpe, Karel;Igodt, Paul;Malfait, Wim
    • 대한수학회지
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    • 제38권5호
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    • pp.883-914
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    • 2001
  • We present a survey of research results obtained for infra-nilmanifolds, their fundamental groups and some of their generalizations. This is presented from two different approaches and covers achievements obtained during the past four decades and showing a remarkable amount of mathematical interdisciplinarity. We go more in depth concerning the existence and construction of polynomial structures for these manifolds and groups, a direction where significant progress was made in the past few years. The bounded-degree polynomial structures developed by the authors triggered a number of challenging open problems. Also, their study already has lead to some interesting results concerning e.g. Anosov diffeomorphisms and expanding maps.

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지중공동을 고려한 지반-말뚝-구조물 상호작용계의 지진응답해석 (Seismic Response Analysis of Soil-Pile-Structure Interaction System considering the Underground Cavity)

  • 김민규;임윤묵;김문겸;이종세
    • 한국지진공학회:학술대회논문집
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    • 한국지진공학회 2002년도 춘계 학술발표회 논문집
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    • pp.117-124
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    • 2002
  • The major purpose of this study is to determine the dynamic behavior of soil-pile-structure interaction system considering the underground cavity. For the analysis, a numerical method fur ground response analysis using FE-BE coupling method is developed. The total system is divided into two parts so called far field and near field. The far field is modeled by boundary element formulation using the multi-layered dynamic fundamental solution that satisfied radiational condition of wave. And this is coupled with near field modeled by finite elements. For the verification of dynamic analysis in the frequency domain, both forced vibration analysis and free-field response analysis are performed. The behavior of soil non-linearity is considered using the equivalent linear approximation method. As a result, it is shown that the developed method can be an efficient numerical method to solve the seismic response analysis considering the underground cavity in 2D problem.

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