• Title/Summary/Keyword: general forms

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Central Crack in a Piezoelectric Disc

  • Kwon, Jong-Ho
    • Journal of Mechanical Science and Technology
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    • v.18 no.9
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    • pp.1549-1558
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    • 2004
  • This study is concerned with the general solution of the field intensity factors and energy release rate for a Griffith crack in a piezoelectric ceramic of finite radius under combined anti-plane mechanical and in-plane electrical loading. Both electrically continuous and impermeable crack surface conditions are considered. Employing Mellin transforms and Fourier series, the problem is reduced to dual integral forms. The solution to the resulting expressions is expressed in terms of Fredholm integral equation of the second kind. The solutions are provided to study the influence of the crack length, the crack surface boundary conditions on the intensity factors and the energy release rate.

A Study on the Calibration of Z-axis Depth of Cut using AE Signal in Micro-machining (마이크로 가공에서 AE 신호를 이용한 z 축 절삭깊이 보정에 관한 연구)

  • Kang I.S.;Kim J.H.;Kang M.C.;Lee K.Y.;Kim J.S.;Ahn J.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.410-413
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    • 2005
  • There are technical requirements to manufacture large size functional parts with not only simple geometries like a flat or spherical surface but also sculptured geometries. In addition, the required machining accuracy for these parts is becoming more severe day-by-day. In general, the forms of machined parts are determined by relative position between the workpiece and the tool during cutting. To improve machining accuracy, the relative position error should be maintained within the required accuracy. This study deals with estimation and calibration of depth of cut using AE signal in micro-machining.

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A Remote Data Access Interface Model Using the Monitor IPC Mechanism

  • 김동규
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.16 no.4
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    • pp.358-381
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    • 1991
  • In this paper, we construct a remote data access interface model using the IPC mechanism based on the monitor concept. A general purpose IPC mechanism which can be used to implement arbitrary forms of communications control over distributed processes in a network environment is developed as a basis to build the framework for the model. The interface model and synchronization mechanisms are presented for providing application processes with remote data access capability using the above IPC mechanism.

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An Effective Denoising Method for Images Contaminated with Mixed Noise Based on Adaptive Median Filtering and Wavelet Threshold Denoising

  • Lin, Lin
    • Journal of Information Processing Systems
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    • v.14 no.2
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    • pp.539-551
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    • 2018
  • Images are unavoidably contaminated with different types of noise during the processes of image acquisition and transmission. The main forms of noise are impulse noise (is also called salt and pepper noise) and Gaussian noise. In this paper, an effective method of removing mixed noise from images is proposed. In general, different types of denoising methods are designed for different types of noise; for example, the median filter displays good performance in removing impulse noise, and the wavelet denoising algorithm displays good performance in removing Gaussian noise. However, images are affected by more than one type of noise in many cases. To reduce both impulse noise and Gaussian noise, this paper proposes a denoising method that combines adaptive median filtering (AMF) based on impulse noise detection with the wavelet threshold denoising method based on a Gaussian mixture model (GMM). The simulation results show that the proposed method achieves much better denoising performance than the median filter or the wavelet denoising method for images contaminated with mixed noise.

The Study for Mitigating Voltage Sags in Distribution System (배전계통에서의 전압저하 저감방법에 관한 연구)

  • 오용택;김진성
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2002.11a
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    • pp.139-145
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    • 2002
  • Recently, power-electronics equipments or machine that microprocessor is included and computers have been installed continuously in industrial process or region of electronics customer. So concern for power quality, especially sags has been increased. Because those equipments are very sensitive to sags. The sag is phenomenon that magnitude of load voltage temporarily decreases because of power system fault. If a certain equipment in industrial process have any trouble result from sag, it can cause utility to be charged for enormous economics loss. Therefore it need to analyze the characteristic of sag and then mitigation method for sags in distribution system in odor to increase reliability. This paper gives an overview of sags characteristic due to short circuit fault in distribution system and after a general discussion of the various forms mitigation, gives a sags mitigation method with concentrating on changing the distribution system like spot network, on-site generation.

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Coefficient Estimation of IIR Digital Filters Using a Real-Coded Genetic Algorithm

  • Lee, Yun-Hyung;So, Myung-Ok;Jin, Gang-Gyoo;Rhyu, Keel-Soo
    • Journal of Advanced Marine Engineering and Technology
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    • v.31 no.7
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    • pp.863-871
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    • 2007
  • This paper proposes a methodology to estimate the system coefficients for the infinite impulse response(IIR) digital filters using real code GA. In the traditional real coded GA, it adapts the general genetic operations, whereas in this paper the proposed real coded GA applies improved genetic operations in order to search the optimal solution in given problems. Each of unknown IIR digital coefficients collected as forms of a chromosome. Two illustrative examples including the band pass and band stop IIR digital filters are demonstrated to verify the proposed method.

Optimal Force Distribution for Quadruped Walking Robots with a Failed Leg (고장 난 다리가 있는 사족 보행 로봇을 위한 최적 힘 배분)

  • Yang, Jung-Min
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.3
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    • pp.614-620
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    • 2009
  • The force distribution in multi-legged robots is a constrained, optimization problem. The solution to the problem is the set points of the leg contact forces for a particular system task. In this paper, an efficient and general formulation of the force distribution problem is developed using linear programming. The considered walking robot is a quadruped robot with a locked-joint failure, i.e., a joint of the failed leg is locked at a known place. For overcoming the drawback of marginal stability in fault-tolerant gaits, we define safety margin on friction constraints as the objective function to be maximized. Dynamic features of locked-joint failure are represented by equality and inequality constraints of linear programming. Unlike the former study, our result can be applied to various forms of walking such as crab and turning gaits. Simulation results show the validity of the proposed scheme.

A Study on Comparing Characteristics of Philippe Starck's furniture design with Ron Arad's (필립 스탁과 론 아라드의 가구디자인 특성 비교 연구)

  • Lee Jin-Young
    • Korean Institute of Interior Design Journal
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    • v.14 no.5 s.52
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    • pp.193-204
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    • 2005
  • Design took a radical turn in the 1980's, deconstructing the rigid ideology of the Modernism, often with great humor. Contemporary representable Avant-garde designers, Philippe Starck and Ron Arad brazenly borrowed from the 'historical elements' of previous styles and created bio-morphic forms with whimsical names of furniture. This study is proposed to understand the diversity of contemporary design, by comparing these two furniture designers. It also covers the common factors in contemporary furniture design, and analyzes their individual differences and similarities in design. It helps to plan the foundation of design methods for 21C, and predict and respond to the future as a reference point. Philippe Starck links Romantic Rationalism within Minimal style and Ron Arad links Deconstructivism within High-tech style but both of them pursue of Organic concept design in their furniture through the concept of humanism. They are able to establish a base of contemporary furniture design by adapting new conceptual form, and design process for the general public.

A study on ubiquitous technology in information science (정보과학의 유비쿼터스 연구정책과 기술에 관한 연구)

  • 정창덕
    • Journal of the Korea Computer Industry Society
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    • v.4 no.4
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    • pp.661-670
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    • 2003
  • The most recent paradigm shift is ubiquitous technology, or ubicomp for short. The ubicomp vision pushes computational services out of conventional desktop interfaces and into the environment in increasingly transparent forms. Research in ubiquitous computing raises many challenging issues for computer science in general, but successful research in ubiquitous computing requires the deployment of applications that can survive everyday use, and this in itself presents a great software engineering challenge. We will clarify these problems and discuss our approaches towards their solution. In this paper, we discuss the information technologyproblems that arise in conducting research toward this vision of future computer-enhanced environments.

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SOME GEOMERTIC SOLVABILITY THEOREMS IN TOPOLOGICAL VECTOR SPACES

  • Ben-El-Mechaiekh, H.;Isac, G.
    • Bulletin of the Korean Mathematical Society
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    • v.34 no.2
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    • pp.273-285
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    • 1997
  • The aim of this paper is to present theorems on the exitence of zeros for mappings defined on convex subsets of topological vector spaces with values in a vector space. In addition to natural assumptions of continuity, convexity, and compactness, the mappings are subject to some geometric conditions. In the first theorem, the mapping satisfies a "Darboux-type" property expressed in terms of an auxiliary numerical function. Typically, this functions is, in this case, related to an order structure on the target space. We derive an existence theorem for "obtuse" quasiconvex mappings with values in an ordered vector space. In the second theorem, we prove the existence of a "common zero" for an arbitrary (not necessarily countable) family of mappings satisfying a general "inwardness" condition againg expressed in terms of numerical functions (these numerical functions could be duality pairings (more generally, bilinear forms)). Our inwardness condition encompasses classical inwardness conditions of Leray-Schauder, Altman, or Bergman-Halpern types.

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