• Journal of Power Electronics
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• 제9권1호
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• pp.74-84
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• 2009

The design and implementation of a high performance PID (Proportional Integral & Differential) style controller with zero-phase error tracking property is considered in this article. Unlike a ball screw driven system, the controller in a direct drive system should provide a high level of tracking performance while avoiding the problems due to the absence of the gear system. The stiff mechanical element in a direct drive system allows high precise positioning capability, but relatively high tracking ability with minimal position error is required. In this work, a feasible position controller named 'Unified PID controller' is presented. It will be shown that the function of the closed position loop can be designed into unity gain system in continuous time domain to provide minimal position error. The focus of this work is in two areas. First, easy gain tunable PID position controller without speed control loop is designed in order to construct feasible high performance drive system. Second, a simple but powerful zero phase error tracking strategy using the pre-designed function of the main control loop is presented for minimal tracking error in all operating conditions. Experimental results with a s-curve based position pattern commonly used in industrial field demonstrate the feasibility and effective performance of the approach.

• 전기의세계
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• 제29권3호
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• pp.185-192
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• 1980

It is revealed that duality and similarity between both capacitance and inductance systems coexist, and also that the former is more efficient than the latter in application viewpoints in time-invariant linear cases as far as both systems are concerned. This paper, using the similarity relation, proposes a new magnetics capacity concept similar to electrostatic capacity so that inductance systems may be interpreted as the corresponding capacitance systems. The new concept makes it convenient to analyze the both systems by unified approach. Finally an example demonstrates the applicability and convenience of the proposed method, through the analysis of capacitances and inductances on the transposed transmission line.

• 제어로봇시스템학회논문지
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• 제10권8호
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• pp.711-717
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• 2004

We propose a path planning method to improve the productivity of SMT (surface mount technology) inspection machines with an area camera. A unified method is newly proposed to determine the FOV clusters and camera sequence simultaneously. The proposed method is implemented by a hybrid genetic algorithm to increase the convergence speed. Comparative simulation results are then presented to verify the usefulness of the proposed algorithm.

• International Journal of Control, Automation, and Systems
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• 제6권6호
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• pp.939-947
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• 2008

The paper proposes a new formulation of the output feedback pole assignment problem. In this formulation, a unified approach is presented for solving the pole assignment problem with various additional objectives. These objectives include optimizing a variety of performance indices, and imposing constraints on the output feedback matrix structure, e.g. decentralized structure. Conditions for the existence of the output feedback are discussed. However, the thrust of the paper is on the development of a convergent pole assignment algorithm. It is shown that when exact pole assignment is not possible, the method can be used to place the poles close to the desired locations. Examples are provided to illustrate the method.

• 한국군사과학기술학회지
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• 제3권2호
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• pp.149-155
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• 2000

This paper presents results from a computer-aided systems engineering application to system development projects. RDD-100 version of ALC Inc. was used in this work. The framework adopted in the study takes a unified approach to the system design and the process management associated with it, thereby coherent and full traceability between them is maintained. Conventional system engineering process supported by the tool is adopted in the system design. On the other hand, the same tool is also used to the systems engineering management to get full traceability between system design data and engineering management data. It is greatly helpful in managing many sub-contractors in the sense that the traceability can help identify the sub-project responsibility as well as the objectives of the project in coordination with interface requirements. We conclude with the advantage and limits of our unified approach.

• Steel and Composite Structures
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• 제42권4호
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• pp.477-487
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• 2022

The shear stiffness of headed-stud shear connectors has no unified definition due to the nonlinear characteristics of its load-slip relationship. A unified framework was firstly adopted to develop a general expression of shear load-slip equation for headed-stud shear connectors varying in a large parameter range based on both force and energy balance. The pre- and post-yield shear stiffness were then determined through bilinear idealization of proposed shear load-slip equation. An updated and carefully selected push-out test database of 157 stud shear connectors, conducting on studs 13~30mm in diameter and on concretes 30~180 MPa in cubic compressive strength, was used for model regression and sensitivity analysis of shear stiffness. An empirical calculation model was also established for the stud shear stiffness. Compared with the previous models through statistical analysis, the proposed model demonstrates a better performance to predict the shear load-slip response and stiffness of the stud shear connectors.

• 보건행정학회지
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• 제28권3호
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• pp.315-319
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• 2018

This paper aims to make a step-by-step strategy to formulate an unified health system by clarifying and overcoming challenges facing South and North Korea and to estimate costs needed for South Korea to assist North Korea to recover to normal health delivery system. We explored implications through literature review and estimated costs under the assumption that supportive activities be provided for 5 years in three ways: support for the development of health and medical care manpower; support for health and medical facilities; and support for the provision of both preventive and primary health care. Step-by-step strategy is formulated for a unified health system with the cost estimation resulting as follows: in case of basic scenario, a total of 3 trillion and 341 billion won (at present value of the year 2017) is in need for the 5-year period at the initial 'recovery support stage' with 135.9 billion won for the development of health and medical care manpower, approximately 2 trillion won for health and medical facilities, and 1.2 trillion won for the provision of both preventive and primary health care. Step-by-step approach is more realistic and applicable in formulating unified health system. Suggested stages are 'recovery support stage,' 'system homogenization stage,' and 'unified system stage.' Strategies at 'recovery support stage' suggested in this paper need to be pursued and followed by those at 'system homogenization stage' and 'unified system stage.'

• 인터넷정보학회논문지
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• 제5권4호
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• pp.95-113
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• 2004

RUP(Rational Unified Process) 객체 지향적이며 사용사례 및 아키텍처 중심의 반복적인 개발방법론이다. 이전에 수행된 대부분 공공분야의 대규모 소프트웨어 개발은 폭포수형 개발 프로세스를 적용하였으나 최근에는 소프트웨어 개발에 따른 위험을 최소화 하고 품질을 향상하기 위하여 RUP와 같은 반복 개발방법의 적용을 시도하고 있다. 그러나 대규모 복합 체계의 개발 프로세스와 그 일부인 소프트웨어 개발 프로세스로서 RUP를 적용한 국내의 연구 자료는 미흡한 실정이다. 본 논문에서는 RUP를 기반으로 복합 체계의 일부인 소프트웨어를 개발하는 프로세스를 고찰하고자 한다. 이를 위하여 국내 CIS 소프트웨어 개발 사례를 통하여 체계개발 프로세스와 통합된 RUP프로세스를 제시하고 기존의 폭포수형 프로세스 및 RUP와 비교 경가론 한다. 된 논문의 연구결과는 공공기관에서 대규모 복합체계의 소프트웨어를 개발하는 경우에 RUP 기반 프로세스의 조정, 개발관리에 있어서 위헌의 최소화와 최종 제품의 품질향상에 기여한 것으로 믿는다.

• Computers and Concrete
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• 제34권3호
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• pp.307-328
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• 2024

The concrete damage plasticity (CDP) model is widely used to simulate concrete behaviour using either implicit or explicit analysis methods. To effectively execute the models and resolve convergence issues in implicit analysis, activating the viscosity parameter of this material model is a common practice. Despite the frequent application of implicit analysis to analyse concrete structures with the CDP model, the viscosity parameter significantly varies among available models and lacks consistency. The adjustment of the viscosity parameter at the element/structural level disregards its indirect impact on the material. Therefore, the accuracy of the numerical model is confined to the validated range and might not hold true for other values, often explored in parametric studies subsequent to validations. To address these challenges and develop a unified numerical model for varied conditions, a quasi-static analysis using the explicit solver was conducted in this study. Fifteen thick flat plates tested under load control with different geometries and different eccentric loads were considered to verify the accuracy of the model. The study first investigated various concrete material behaviours under compression and tension as well as the concrete tensile strength to identify the most reliable models from previous methodologies. The study compared the results using both implicit and explicit analysis. It was found that, in implicit analysis, the viscosity parameter should be as low as 0.0001 to avoid affecting material properties. However, at the structural level, the optimum value may need adjustment between 0.00001 to 0.0001 with changing geometries and loading type. This observation raises concerns about further parametric study if the specific value of the viscosity parameter is used. Additionally, activating the viscosity parameter in load control simulations confirmed its inability to capture the peak load. Conversely, the unified explicit model accurately simulated the behaviour of the test specimens under varying geometries, load eccentricities, and column sizes. This study recommends restricting implicit solutions to the viscosity values proposed in this research. Alternatively, for highly nonlinear problems under load control simulation, explicit analysis stands as an effective approach, ensuring unified parameters across a wide range of applications without convergence problems.

• International Journal of Control, Automation, and Systems
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• 제3권2호
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• pp.159-165
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• 2005

This paper designs observers for matrix second-order linear systems on the basis of generalized eigenstructure assignment via unified parametric approach. It is shown that the problem is closely related with a type of so-called generalized matrix second-order Sylvester matrix equations. Through establishing two general parametric solutions to this type of matrix equations, two unified complete parametric methods for the proposed observer design problem are presented. Both methods give simple complete parametric expressions for the observer gain matrices. The first one mainly depends on a series of singular value decompositions, and is thus numerically simple and reliable; the second one utilizes the right factorization of the system, and allows eigenvalues of the error system to be set undetermined and sought via certain optimization procedures. A spring-mass system is utilized to show the effect of the proposed approaches.