• 제목/요약/키워드: Bond graph

검색결과 69건 처리시간 0.023초

Evolutionary Design for Multi-domain Engineering System - Air Pump

  • 서기성
    • 한국지능시스템학회:학술대회논문집
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    • 한국퍼지및지능시스템학회 2005년도 추계학술대회 학술발표 논문집 제15권 제2호
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    • pp.323-326
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    • 2005
  • This paper introduces design method for air pump system using bond graph and genetic programming to maximize outflow subject to a constraint specifying maximum power consumption. The air pump system is a mixed domain system which includes electromagnetic, mechanical and pneumaticelements. Therefore an appropriate approach for a better system for synthesis is required. Bond graphs are domain independent, allow free composition, and are efficient for classification and analysis of models, Genetic programming is well recognized as a powerful tool for open-ended search. The combination of these two powerful methods for evolution of multi-domain system, BG/GP, was tested for redesign of air pump system.

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루프형성 기법을 이용한 편심배치방식 자기부상 시스템의 강인 LQ 제어 (Robust LQ control of magnetically levitation systems with a combined lift and guidance using loop-shaping techniques)

  • 박전수;김종식
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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    • pp.747-753
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    • 1992
  • The modeling and control design schemes are developed for maglev systems with a combined lift and guidance. First, bond graph techniques are applied for modeling these multi-energy domain systems more logically and systematically. And the stability loop via pole placement and the performance loop via loop-shaping LQ control are designed. The suggested controller satisfies the required characteristics of stability and performance simultaneously. Finally, the robustness of the synthesized maglev control system is evaluated for the variations of air gap and vehicle mass through computer simulation.

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An Inclusive Evaluation of Linkage Between Environmental Managerial Accounting and Knowledge Management: Empirical Evidence from Vietnam

  • HUYNH, Quang Linh
    • The Journal of Asian Finance, Economics and Business
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    • 제9권7호
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    • pp.135-144
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    • 2022
  • The relationship between applying knowledge management and accepting environmentally managed accounting is more complicated than previous studies suggested. Knowledge management is both an antecedent and a consequence of implementing environmentally managed accounting in the workplace. Nonetheless, none of the prior studies have systematically investigated this relationship. The current article attempted to scrutinize the reciprocated multifaceted tie between environmental managerial accounting and knowledge management by utilizing the methods of directed graph searches as well as directed acyclic graphs. The research data was gathered from 342 publicly-listed corporations in Vietnam's key stock markets. The empirical findings disclose that implementing knowledge management can lead to adopting environmental managerial accounting in business, which is, in turn, an antecedent of accepting knowledge management. More importantly, the current research found that the adoption of knowledge management is the first factor to affect the research model. Nonetheless, the usage of knowledge management in business can, in turn, have a positive effect back to the implementing extent of environmental managerial accounting. The findings are beneficial to scientists and particularly to executives by shedding new insight into this reciprocated bond, which can lead executives to make sound decisions regarding knowledge management and environmental managerial accounting for businesses to acquire competitive advantages.

고속/정밀 위치제어시스템의 모델인 및 제어에 관한 연구 (A Study on the Modeling and Control of High-Speed/High-Accuracy Position Control System)

  • 박민규;한창수
    • 제어로봇시스템학회논문지
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    • 제7권5호
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    • pp.399-406
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    • 2001
  • This paper presents a dynamic modeling and a sliding mode controller for the high-speed/high-accuracy position control system. The selected target system is the wire bonder assembly which is used in the semiconductor assembly process. This system is a reciprocating one around the pivot point that consists of VCM(voice coil motor) as an actuator and transducer horn as a bonding tool. For the modeling elements, the sys-tem is divided into electrical circuit, magnetic circuit and mechanical system. Each system is modeled using the bond graph method and united into the full system. Two major aims are considered in the design of the controller. The first one is that the horn must track the given reference trajectory. The second one is that the controller must be realizable by using the DSP board. Computer simulation and experimental results show that the designed sliding mode controller provides better performance than the PID controller.

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편심배치방식 자기부상 제어시스템의 2차 현가에 대한 동특성 해석 (Dynamic Performance Analysis for Secondary Suspension of Maglev Control Systems with a Combined Lift and Guidance)

  • 김종식
    • 한국정밀공학회지
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    • 제9권1호
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    • pp.53-65
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    • 1992
  • For improving the performance of maglev systems with a combined lift and guidance, it is suggested that the multivariable control systems and a secondary suspension should be added. The former is required to reject both track irregularities in vertical disturbances and wind gusts in lateral disturbances, and the latter to guarantee passengers against an unsatisfied criteria in ride quality. In this paper, bond graph model for the study of nonlinear dynamics of maglev systems with a combined lift and guidance is presented briefly. And, the secondary suspension is analyzed to understand the role of stiffness and damping factors in passive devices. Finally, LQG/LTR mulitivariable control systems are designed for the overall maglev systems with and without secondary suspension, and then the system performances in these two cases are evaluated.

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고속/정밀 위치제어시스템의 모델링 및 제어에 관한 연구 (A Study on the Modeling and Control of High-Speed/High-Accuracy Position Control System)

  • 신호준;박민규;윤석찬;한창수
    • 한국공작기계학회:학술대회논문집
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    • 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
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    • pp.83-89
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    • 2000
  • This paper presents a dynamic modeling and a sliding mode controller for the high-speed / high-accuracy position control system. Selected target system is the wire bonder head assembly which is used in semiconductor assembly process. This system is a reciprocating one around the pivot point that consists of VCM(voice coil motor) as a actuator and transducer horn as a bonding tool. For the modeling elements, the system is divided into electrical circuit, magnetic circuit and mechanical system. Each system is modeled by using the bond graph method and united into the full system. Two major aims are considered in the design of the controller. The first one is that the horn must track the given reference trajectory. The second one is that the controller must be realizable by using the DSP board. Computer simulation and experimental results show that the designed sliding mode controller provides better performance than the PID controller.

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구조적으로 열린 공학 디자인을 위한 진화적설계 방법론 (Evolutionary Design Methodology for Topology Open-ended Engineering Design)

  • 서기성
    • 한국지능시스템학회:학술대회논문집
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    • 한국퍼지및지능시스템학회 2005년도 춘계학술대회 학술발표 논문집 제15권 제1호
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    • pp.189-192
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    • 2005
  • 공학시스템의 설계 문제는 시스템 구성이 복잡하고, 구조적으로 열려있으며, 전기, 기계, 유압, 열등의 서로 다른 에너지 도메인 구성 요소를 포함한다. 최적의 설계를 위해서는 각 도메인에 대한 통합된 설계 방법과 자동적이고 구조적으로 열린 공간에 대한 효율적인 탐색방법이 요구된다. 본 논문은 도메인에 독립적이며 모델링과 해석에 장점을 가진 본드 그래프 (bond graph)와 대규모 공간 해의 탐색에 접합한 진화 알고리즘의 일종인 유전자 프로그래밍(Genetic Programming)을 결합하여 멀티 도메인 동적시스템에 대한 디자인 해를 자동적으로 생성해주는 설계 방법을 제시하고, 제안된 설계방법의 효용성을 입증하기 위해서 이를 아나로그 필터 설계에 문제에 적용하였다.

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다양한 다분류 SVM을 적용한 기업채권평가 (Corporate Bond Rating Using Various Multiclass Support Vector Machines)

  • 안현철;김경재
    • Asia pacific journal of information systems
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    • 제19권2호
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    • pp.157-178
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    • 2009
  • Corporate credit rating is a very important factor in the market for corporate debt. Information concerning corporate operations is often disseminated to market participants through the changes in credit ratings that are published by professional rating agencies, such as Standard and Poor's (S&P) and Moody's Investor Service. Since these agencies generally require a large fee for the service, and the periodically provided ratings sometimes do not reflect the default risk of the company at the time, it may be advantageous for bond-market participants to be able to classify credit ratings before the agencies actually publish them. As a result, it is very important for companies (especially, financial companies) to develop a proper model of credit rating. From a technical perspective, the credit rating constitutes a typical, multiclass, classification problem because rating agencies generally have ten or more categories of ratings. For example, S&P's ratings range from AAA for the highest-quality bonds to D for the lowest-quality bonds. The professional rating agencies emphasize the importance of analysts' subjective judgments in the determination of credit ratings. However, in practice, a mathematical model that uses the financial variables of companies plays an important role in determining credit ratings, since it is convenient to apply and cost efficient. These financial variables include the ratios that represent a company's leverage status, liquidity status, and profitability status. Several statistical and artificial intelligence (AI) techniques have been applied as tools for predicting credit ratings. Among them, artificial neural networks are most prevalent in the area of finance because of their broad applicability to many business problems and their preeminent ability to adapt. However, artificial neural networks also have many defects, including the difficulty in determining the values of the control parameters and the number of processing elements in the layer as well as the risk of over-fitting. Of late, because of their robustness and high accuracy, support vector machines (SVMs) have become popular as a solution for problems with generating accurate prediction. An SVM's solution may be globally optimal because SVMs seek to minimize structural risk. On the other hand, artificial neural network models may tend to find locally optimal solutions because they seek to minimize empirical risk. In addition, no parameters need to be tuned in SVMs, barring the upper bound for non-separable cases in linear SVMs. Since SVMs were originally devised for binary classification, however they are not intrinsically geared for multiclass classifications as in credit ratings. Thus, researchers have tried to extend the original SVM to multiclass classification. Hitherto, a variety of techniques to extend standard SVMs to multiclass SVMs (MSVMs) has been proposed in the literature Only a few types of MSVM are, however, tested using prior studies that apply MSVMs to credit ratings studies. In this study, we examined six different techniques of MSVMs: (1) One-Against-One, (2) One-Against-AIL (3) DAGSVM, (4) ECOC, (5) Method of Weston and Watkins, and (6) Method of Crammer and Singer. In addition, we examined the prediction accuracy of some modified version of conventional MSVM techniques. To find the most appropriate technique of MSVMs for corporate bond rating, we applied all the techniques of MSVMs to a real-world case of credit rating in Korea. The best application is in corporate bond rating, which is the most frequently studied area of credit rating for specific debt issues or other financial obligations. For our study the research data were collected from National Information and Credit Evaluation, Inc., a major bond-rating company in Korea. The data set is comprised of the bond-ratings for the year 2002 and various financial variables for 1,295 companies from the manufacturing industry in Korea. We compared the results of these techniques with one another, and with those of traditional methods for credit ratings, such as multiple discriminant analysis (MDA), multinomial logistic regression (MLOGIT), and artificial neural networks (ANNs). As a result, we found that DAGSVM with an ordered list was the best approach for the prediction of bond rating. In addition, we found that the modified version of ECOC approach can yield higher prediction accuracy for the cases showing clear patterns.

본드선도 모델링 방법의 기본개념 및 그 적용 예 (Basic Concepts of Bond Graph Modeling Techniques and It's Applications)

  • 김종식;박전수
    • 기계저널
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    • 제33권1호
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    • pp.22-32
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    • 1993
  • 본드선도는 물리적 등가가 적용되는 모든 상사 시스템을 대단히 조직이며 일관성 있게 모델링할 수있을 뿐만 아니라 시스템의 동적 방정식을 제어동역학 관점에 유리한 상태방정식으로 직접 유도할 수 있다. 또한 본드선도는 모델링 단계에서 무시된 각 요소들의 동적 특성 즉, 기계시스 템에서 회전축의 탄성처짐이나 운동 물체들 사이의 마찰 효과 전기 . 자기시스템에서 자속유출량, 그리고 유체 . 유압시스템에서 밀봉부분의 유량손실이나 압축성 유체 특성 등을 기곤에 구성된 본드선도의 변경 없이 각 특성들이 나타나는 본드상에 적절한 접합요소와 함께 단순히 첨가하여 고려할 수 있기 때문에 모델링 과정을 다시 반복하지 않고도 무시된 동적 특성들이 전체시스템에 미치는 영향을 파악할 수 있다. 특히 본드선도가 에너지 변환 장치나 에너지 유동 메카니즘이 복잡한 다에너지역 시스템 등에 거동이 전체시스템에 미치는 효과를 시각적으로 보다 세밀히 파악할 수 있을 뿐만 아니라 구성된 본드선도에 인과관계를 할당하여 본드선도의 접합요소를 통하여 유도된 최종적인 동적 방정식이 현실적으로 실현 가능한 물리시스템인지 파악할 수 있어 본드선도 모델링 단계에서 시스템을 묘사하는 동적 방정식의 옳고 그름을 평가할 수 있다. 이와 같이 본드선도는 기계, 전기 . 자기, 유체 . 유압, 열 시스템 및 이들이 조합된 복잡한 다에너지역 시스템 등을 효과적으로 모데링할 수 있는 매우 유용한 동적 시스템 모델링 방법이다.

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연속가변 ER 댐퍼의 제어 및 응답특성 (Control and Response Characteristics of a Continuously Variable ER Damper)

  • 최승복;최영태;박우철;정재천;서문석;여문수
    • 한국자동차공학회논문집
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    • 제4권6호
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    • pp.164-174
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    • 1996
  • This paper presents control and response characteristics of a continuously variable ER(electrorheological) damper for small-sized vehicles. The ER damper is devised and its governing equation of motion is derived from the bond graph model. The field-dependent yield shear stresses are distilled from experimental investigation on the Bingham property of the ER fluid. The distilled data are incorporated into the governing system model and, on the basis of this model, an appropriate size of the ER damper is manufactured. After evaluating the field-dependent damping performance of the proposed ER damper, the skyhook control algorithm is formulated to achieve desired level of the damping force. The controller is then experimentally implemented and control characteristics of the ER damper are presented in order to demonstrate superior controllability of the damping force. In addition, response characteristics of the damping force with respect to the electric field with fast on-off frequency are provided to show the feasibility of practical application.

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