• 대한전자공학회논문지SD
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• 제41권2호
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• pp.67-75
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• 2004

본 논문은 인덕턴스 성분을 포함한 단일 도선 및 트리 구조 RLC 연결선의 버퍼 삽입 방법을 제시한다. 이를 위해 먼저 CMOS 버퍼가 구동하는 단일 RLC 도선에 대한 시간 지연의 대수식을 제시한다. 이 수식은 현재의 서브마이크로미터 공정을 위한 n-th power law 기반에서 유도되었으며, 다양한 RLC 부하를 가지고 실험해 본 결과, 실제 SPICE 시뮬레이션 결과에 비해 최대 9％ 오차를 갖는 것으로 나타났다. 본 논문은 이 지연 시간 수식을 바탕으로 단일 도선 RLC 연결선을 여러 개로 나누는 버퍼 삽입에 관한 수식과 RLC 트리 연결선의 시간 지연을 최적화하기 위해 삽입될 버퍼의 사이즈를 결정하는 알고리듬을 제시한다. 제시된 버퍼 삽입 알고리듬은 0.25㎛ CMOS 공정의 트리 연결선에 적용하였으며, HSPICE 결과를 이용하여 정확도를 검증하였다.

• Journal of Information Technology Applications and Management
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• 제27권3호
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• pp.69-75
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• 2020

In this paper, we applied the shape parameters of the exponentialized exponential life distribution widely used in the field of software reliability, and compared the reliability properties of the software using the non-homogeneous Poisson process in finite failure. In addition, the average value function is also a non-decreasing form. In the case of the larger the shape parameter, the smaller the estimated error in predicting the predicted value in comparison with the true value, so it can be regarded as an efficient model in terms of relative accuracy. Also, in the larger the shape parameter, the larger the estimated value of the coefficient of determination, which can be regarded as an efficient model in terms of suitability. So. the larger the shape parameter model can be regarded as an efficient model in terms of goodness-of-fit. In the form of the reliability function, it gradually appears as a non-increasing pattern and the higher the shape parameter, the lower it is as the mission time elapses. Through this study, software operators can use the pattern of mean square error, mean value, and hazard function as a basic guideline for exploring software failures.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1074-1078
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• 2005

In precision positioning applications, such as scanning tunneling microscopy and diamond turning machines [1], it is often required that actuators have nanometer resolution in displacement, high stiffness, and fast frequency response. These requirements are met by the use of piezoceramic actuators. A major limitation of piezoceramic actuators, however, is their lack of accuracy due to hysteresis nonlinearity and drift. The maximum error due to hysteresis can be as much as 10-15% of the path covered if the actuators are run in an open-loop fashion. Hence, the accurate control of piezoceramic actuators requires a control strategy that incorporates some form of compensation for the hysteresis. One approach is to develop an accurate model of the hysteresis and the use the inverse as a compensator. The Preisach model has frequently been employed as a nonlinear model for representing the hysteresis, because it encompasses the basic features of the hysteresis phenomena in a conceptually simple and mathematically elegant way. In this paper, a new numerical inversion scheme of the Preisach model is developed with an aim of compensating hysteresis in piezoceramic actuators. The inversion scheme is implemented using the first-order reversal functions and is presented in a recursive form. The inverted model is then incorporated in an open-loop control strategy that regulates the piezoceramic actuator and compensates for hysteretic effects. Experimental results demonstrate satisfactory regulation of the position of the piezoceramic actuator to the desired trajectories.

• 대한기계학회논문집
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• 제17권8호
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• pp.1883-1897
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• 1993

Interactive computer-aided analysis of mechanical systems has recently been undergoing an evolution due to highly efficient computer graphics. The industrial implementation of state-of-the-art analytical developments in mechanisms has been facilitated by computer-aided design packages because these rigid-body mechanism analysis programs dramatically reduce the time required for linkage design. This paper proposes a component modular approach to computeraided kinematic motion analysis for general planar multiloop mechanisms. Most multiloop mechanisms can be decomposed into serveral components. The kinematic properties (position, velocity, and acceleration) of every node can then be determined from the kinematic analysis of the corresponding component modules by a closed-form solution procedure. In this paper, 8 types of modules are defined and formulations for kinematic analysis of the component modules are derived. Then a computer-aided kinematic analysis program is developed using the proposed approach and the solution procedure of an example shows the effectiveness and accuracy on the approach.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.818-821
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• 2004

With a rapid development in the area of micro and ultra precision technology, the micro surface machining of small size parts are explosively increased. Especially, to improve efficiency of various beams in lens and reflector, non-rotational symmetric form and several mm level heights changeable surface can be machined at a time. These geometric complex 3D surface cannot be machined by general short stroke FTS. The long stroke FTS if firmly needed to move directly several mm and have nm level positioning accuracy for the complex surface form. The long stroke FTS used linear motors to drive moving unit long and fine, aero static bearings to decrease friction and moving errors in guide way, optical linear scale with nm level resolution to measure position of FTS. Furthermore, to increase the performance of acceleration of FTS, the light material, such as AL is used for the structure and the high stiffness box type structure is selected. In this paper, the genetic algorithm approach is described to determine a set of design parameters for auto tuning. The authors have attempted to model the design problem with the objective of minimizing the error, such as variable pattern change. This method can give the better alternative than existing other method.

• 한국정밀공학회지
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• 제18권4호
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• pp.97-103
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• 2001

Accuracy of a machined part is determined by the relative motion between the cutting tool and the workpiece. One of the important factors which affects the relative motion is the geometric errors of a machine tool. In this study, firstly, geometric errors are measured by laser interferometer, and the positioning error of each control point selected uniformly on the control surface CAD model can be estimated from th oirm shaping model and geometric error data base. Where a form shaping function is derived from the link of homogeneous transformation matrix. Secondly, control points are shifted to the estimated amount of positioning errors. A new control surface is modeled with NURBS(Non Uniform Rational B-Spline) surface approximation to the shifted control points. By generating tool paths to the redesigned control surface, we reduce the machining error quite.

• 한국음향학회지
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• 제16권3호
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• pp.81-85
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• 1997

본 논문에서는 3차와 4와의 큐뮬런트를 이용하여 FIR 시스템의 파라메터 추정을 위한 회귀 추정 알고리듬을 제안한다. 제안한 FIR 파라메터 회귀 추정 알고리듬에서 3차와 4차의 큐뮬런트 관계식으로부터 Overdetermined Recurisive Instrumental Variable (ORIV) 형태의 회귀 추정 알고리듬으로 변환할 수 있도록 출력신호로 구성된 행렬식을 얻어낸 후, 이를 전개하여 회귀 추정 알고리듬을 개발한다. 제안한 회귀 추정 알고리듬은 기존의 비회귀 알고리듬의 확장으로 적은 데이터로 수렴이 가능하며, 시변 시스템의 추정에도 용이하다. 또한 3차와 4차의 순수 고차 큐뮬런트로 구성됨에 따라 기존의 2차의 자기상관함수를 이용한 회귀 추정 알고리듬에 비해 가산 가우시안 잡음에 의한 추정 오차를 줄일 수 있는 장점이 있다.

• 대한전자공학회논문지
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• 제26권11호
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• pp.1666-1671
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• 1989

A novel switched-capacitor circuit for interfacing capacitive microtransducers with a digital system is developed based on the dual-slope integration. It consists of a differential integrator and a comparator. Driven by the teo phase clock, the circuit first senses the capacitance difference between the transducer and the reference capacitor in the form of charge, and accumulates it into the feedback capabitor of the integrator for a fixed period of time. The resulant accumulated charge is next extracted by the known reference charge until the integrator output voltage refurns to zero. The length of time required for the integrator output to return to zero, as measured by the number of clock cycle gated into a counter is proportional to the capacitance difference, averaged over the integration period. The whole operation is insensitive to the reference voltage and the capacitor values involved in the circuit, Thus the proposed circuit permits an accurate differental capacitance measurement. An error analysis has showh that the resolution as high as 8 bits can be expected by realizing the circuit in a monolithic MOS IC form. Besides the accuracy, it features the small device count integrable onto a small chip area. The circuit is thus particularly suitadble for the on-chip interface.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1130-1135
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• 2003

The need to increase the reliability of a structural system has been significantly brought in the procedure of real designs to consider, for instance, the material properties or geometric dimensions that reveal a random or incompletely known nature. Reliability based design optimization of a real system now becomes an emerging technique to achieve reliability, robustness and safety of these problems. Finite element analysis program and the reliability analysis program are necessary to evaluate the responses and the probabilities of failure of the system, respectively. Moreover, integration of these programs is required during the procedure of reliability based design optimization. It is well known that reliability based design optimization can often have so many local minima that it cannot converge to the specified probability of failure. To overcome this problem, barrier function method in reliability based design optimization is suggested. To illustrate the proposed formulation, reliability based design optimization of a bracket is performed. AMV and FORM are employed for reliability analysis and their optimization results are compared based on the accuracy and efficiency.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1992년도 추계학술대회 논문집
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• pp.136-144
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• 1992

Recently, Silicon Nitrde ceramic is regarded as the representative engineering ceramic with the excellent mechanical properties and many functions for mechanical components and parts among various kinds of ceramics in the mechanical industry. But, during the manufacturing of engineering ceramics, there is many volumetric shrinkage coupled with a distortion of the parts which is produced. Due to the requirement for high accuracy of size, form, and surface finish of the components, machining is needed surely. Nowdays, grinding with a resin bond type diamond wheels has been generally applied to machining of the engineering ceramics in the whole world because that it can be conveniently proceeded for workers to dress of tool and made with high reliability in producing factories among many bond type super-abrasive wheels yet. It is important task for attaining prescribed mechanical components with high reliability to observe the grinding mechanism of ceramics as like generation of cracks and chipping of material during process. Because they considerably effects on the strength characteristic of machined mechanical components. In this study, various surface grinding experiments using resin bond type diamond wheels are carried out for Silicon Nitride ceramic. Grinding mechanism of ceramics is observed experimentally and the relationship with various conditions is also attained. Form this experimental study, some useful machining data and information to determine proper machining condition for grinding of Silicon Nitride ceramic is obtained.