• Title/Summary/Keyword: Discrete Support

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Modelling of Railway Tracks for Wave Propagation along Railway Tracks at High Frequencies (철로를 따라 전파되는 파동 해석을 위한 고주파수 대역 철로 모델링)

  • Ryue, Jung-Soo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.21 no.3
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    • pp.248-257
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    • 2011
  • It was reported recently that railpads can be included as a continuous elastic support of the rail and the model was justified from experiments. In general, however, railpads are installed discretely on sleepers with a regular span. The effect of the discrete railpad was not clearly examined so far in such a high frequency range. In this paper, the effect of the railpads in track modelling for high frequencies is investigated by means of the finite element analysis. To do that, the railpads are regarded as 'a continuous elastic support' and 'a discrete elastic support' in this paper. The dispersion relations and decaying features are predicted and compared between the two models up to 80 kHz.

A Study on the Defect Classification of Low-contrast·Uneven·Featureless Surface Using Wavelet Transform and Support Vector Machine (웨이블렛변환과 서포트벡터머신을 이용한 저대비·불균일·무특징 표면 결함 분류에 관한 연구)

  • Kim, Sung Joo;Kim, Gyung Bum
    • Journal of the Semiconductor & Display Technology
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    • v.19 no.3
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    • pp.1-6
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    • 2020
  • In this paper, a method for improving the defect classification performance in steel plate surface has been studied, based on DWT(discrete wavelet transform) and SVM(support vector machine). Surface images of the steel plate have low contrast, uneven, and featureless, so that the contrast between defect and defect-free regions is not discriminated. These characteristics make it difficult to extract the feature of the surface defect image. In order to improve the characteristics of these images, a synthetic images based on discrete wavelet transform are modeled. Using the synthetic images, edge-based features are extracted and also geometrical features are computed. SVM was configured in order to classify defect images using extracted features. As results of the experiment, the support vector machine based classifier showed good classification performance of 94.3%. The proposed classifier is expected to contribute to the key element of inspection process in smart factory.

Gait Control on Slope Way using Zero Moment Point for Robot (Zero Moment Point를 이용한 이족 보행 로봇의 경사로 걸음새 제어에 관한 연구)

  • Um, Seung-Hyun;Lim, Mee-Seub;Lim, Joon-Hong
    • Proceedings of the KIEE Conference
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    • 2006.10c
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    • pp.530-532
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    • 2006
  • In this paper, we propose stable walking algorithm using ZMP for the biped robot in the slope-way. At first, we define discrete state variables that classified stable area and unstable area by center of mass from ZMP during slope-way walking. For the stable walking gait, the discrete state controller for determining the high-level and low-level decision making are designed. The high-level decision making is composed of the discrete state variables; left foot support phase, right foot support phase, flat-way, and slope-way. Then the continuous state controller is implemented for the low-level decision making using ZMP.

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Combined discrete event and discrete time simulation framework for the improvement of shipbuilding process planning (조선 공정 계획의 수립 완성도 향상을 위한 이산 사건 및 이산 시간 혼합형 시뮬레이션 프레임워크)

  • Cha, Ju-Hwan;Roh, Myung-Il;Bang, Kyung-Woon;Lee, Kyu-Yeul
    • Journal of the Korea Society for Simulation
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    • v.17 no.4
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    • pp.71-80
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    • 2008
  • In this study, a simulation framework, which can support developing various simulation systems for the improvement of process planning in shipbuilding such as the block erection, the block turn-over, and so on, is proposed. In addition, a simulation kernel, which is a key component of the simulation framework, is implemented according to the concept of the combined discrete event and discrete time simulation. To evaluate the efficiency and applicability of the proposed simulation framework, it is applied to the block erection process in shipbuilding. The result shows that the proposed simulation framework can provide the consistent, integrated development environment for a simulation system, as compared with existing studies and commercial simulation systems.

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Hybrid Systems Modeling and Simulation - PartI: Modeling and Simulation Methodology (하이브리드 시스템 모델링 및 시뮬레이션 - 제1부: 모델링 및 시뮬레이션 방법론)

  • 임성용;김탁곤
    • Journal of the Korea Society for Simulation
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    • v.10 no.3
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    • pp.1-14
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    • 2001
  • A hybrid system is defined as a mixture of continuous systems and discrete event systems. This paper first proposes a framework for hybrid systems modeling, called Hybrid Discrete Event System Specification (HDEVS) formalism. It then presents a method for simulators interoperation in which a continuous system simulator and a discrete event simulator are executed together in a cooperative manner. The formalism can specify a hybrid system in a way that a continuos system and a discrete event system are separately modeled by their own specification formalisms with a support of well-defined interface. We call such interface an A/E converter for analog-to- event conversion and an E/A converter for event-to-analog conversion. Simulators interoperation is based on the concept of pre-simulation in which simulation time for a continuous simulator is advanced in accordance with a discrete event simulator.

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Eigenvalue Analysis of a Blower Impeller Using Cyclic Symmetry (송풍기 임펠러의 순환대칭성을 이용한 고유치해석)

  • 김창부;안영철
    • Journal of KSNVE
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    • v.10 no.3
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    • pp.523-530
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    • 2000
  • In this paper we present an efficient method for finite element vibration analysis of a structure with cyclic symmetry and applied it to calculating the natural vibration characteristics for a blower impeller. Blower impeller having a cyclically symmetric structure is composed of circumferentially repeated substructures., The whole-structure is partitioned into substructures and then finite element vibration analysis is performed for a substructure using transformed equations for each number of nodal diameter which are derived from discrete Fourier transform in consideration of the cyclic symmetry. natural vibration characteristics for three kinds of models which are blower impeller without support ring with small support ring and with large support ring are numerically analyzed and compared. Accuracy and efficiency of the present method are verified by comparison of results of the analysis with substructure and with whole-structure. Also the results of the analysis by cyclic symmetry module(SOL 115) of MSC/NASTRAN are presented and compared.

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Dynamic Analysis of Floating Bridge with Discrete Pontoons Subject to Earthquake Load (이산 폰툰형 부유식 교량의 지진응답 해석)

  • 권장섭;백인열;장승필
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2002.09a
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    • pp.147-154
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    • 2002
  • Dynamic response analysis are conducted for a floating bridge subjected to multiple support earthquake excitation. The floating bridge used in this study is supported by discrete floating pontoons and horizontal pretension cables supported at both ends of the bridge. The bridge is modeled with finite elements and the hydrodynamic added mass and added damping due to the surrounding fluid around pontoons are obtained using boundary elements. Multiple support excitation is introduced at both ends of the bridge and the time history response is compared to that of a simultaneous excitation. The results shows that the differences between two results are not so large except for cable tension for which the multiple support excitation yields larger values. During the analysis the concept of retardation function is utilized to consider the frequency dependency of the hydrodynamic coefficients.

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Criterion of discrete unimodal mixtures (이산분포 혼합의 단봉성이 성립하기 위한 조건)

  • 최대우
    • The Korean Journal of Applied Statistics
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    • v.8 no.1
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    • pp.159-167
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    • 1995
  • Considering special discrete distribution of exponential family as a sequence with respect to the points of support, the squence is unimodal in some sense. In this paper, we study under what condition the mixture of that discrete distribution with respect to a parameter is unimodal. We derive the maximal interval of the parameter in which each mixture of the discrete distribution such as Binomial and Poisson is always unimodal.

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Dynamic Response of a Beam Structure with Discrete Supports Subjected to a Moving Mass (이동질량에 의한 이산지지 보 구조물의 동적응답)

  • Oh, B.J.;Ryu, B.J.;Lee, G.S.;Lee, Y.S.
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.21 no.3
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    • pp.264-270
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    • 2011
  • This paper deals with dynamic response of a beam structure with discrete spring-damper supports under a moving mass. Governing equations of motion taking into account of all inertia effects of the moving mass were derived by Galerkin's mode summation method, and Runge-Kutta integration method was applied to solve the differential equations. The effects of the speed of the moving mass, spring stiffness, damping coefficient, span number of a beam structure, mass ratio of the moving mass on the dynamic response of the beam structure have been studied. Some numerical results provide design engineers for the beam structure design with discrete supports under a moving mass.

Knowledge Based Recommender System for Disease Diagnostic and Treatment Using Adaptive Fuzzy-Blocks

  • Navin K.;Mukesh Krishnan M. B.
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.18 no.2
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    • pp.284-310
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    • 2024
  • Identifying clinical pathways for disease diagnosis and treatment process recommendations are seriously decision-intensive tasks for health care practitioners. It requires them to rely on their expertise and experience to analyze various categories of health parameters from a health record to arrive at a decision in order to provide an accurate diagnosis and treatment recommendations to the end user (patient). Technological adaptation in the area of medical diagnosis using AI is dispensable; using expert systems to assist health care practitioners in decision-making is becoming increasingly popular. Our work architects a novel knowledge-based recommender system model, an expert system that can bring adaptability and transparency in usage, provide in-depth analysis of a patient's medical record, and prescribe diagnostic results and treatment process recommendations to them. The proposed system uses a set of parallel discrete fuzzy rule-based classifier systems, with each of them providing recommended sub-outcomes of discrete medical conditions. A novel knowledge-based combiner unit extracts significant relationships between the sub-outcomes of discrete fuzzy rule-based classifier systems to provide holistic outcomes and solutions for clinical decision support. The work establishes a model to address disease diagnosis and treatment recommendations for primary lung disease issues. In this paper, we provide some samples to demonstrate the usage of the system, and the results from the system show excellent correlation with expert assessments.