• 한국정밀공학회지
• /
• 제19권9호
• /
• pp.34-40
• /
• 2002

Machining accuracy is affected by quasi-static errors of machining center. Since machine errors have a direct influence upon both the surface finish and geometric shape of the finished workpiece, it is very important to measure the machine errors and to compensate these errors. The laser measurement method for identifying geometric errors of machine tool has the disadvantages such as high cost, long calibration time and usage of volumetric error synthesis model. Accordingly, this paper deals with analysis of the geometric errors of a machine tool using ball bar test without using complicated error synthesis model. Statistical analysis method was adopted in this paper for deriving geometric errors using hemispherical helix ball bar test. As a result of experiment, geometric errors of the vertical machining center are compensated by 88%.

• 품질경영학회지
• /
• 제21권1호
• /
• pp.152-160
• /
• 1993

In developing a quadratic regression relationship, independent variable is frequently measured with error. In this paper the integrated mean square error of prediction is developed for a quadratic functional relationship model as a measure of the effect of measurement error of the independent variable on the predicted values. The amount of the effect of error is presented and illustrated with an example.

• 대한안전경영과학회:학술대회논문집
• /
• 대한안전경영과학회 2009년도 추계학술대회
• /
• pp.187-201
• /
• 2009

Semiconductor industry is based on equipment industry and timing industry. In particular, semiconductor process is very complex and as semiconductor-chip width tails and is becoming equipment gradually more as a high technology. Equipment operation is primarily engaged in semiconductor manufacturing (engineers and operator) of being conducted by, equipment errors have also been raised. Equipment operational data related to the error of korea occupational safety and health agency were based on data and production engineers involved in the operator's questionnaire was drawn through the error factor. Equipment operating in the error factor of 9 big item and 36 detail item detailed argument based on the errors down, and 9 big item the equipment during operation of the correlation error factor was conducted. Each of the significance level was correlated with the tabulation and analysis. Using the maximum correlation coefficient, the correlation between the error factors to derive the relationship between factors were analyzed. Facility operating with the analysis of error factors (big and detail item) derive a relationship between the model saw. The end of the operation of the facility in operation on the part of the two factors appeared as prevention. Safety aspects and ergonomics aspects of the approach should be guided to the conclusion.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국제학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
• /
• pp.746-748
• /
• 1988

A way of improving the transient performance is suggested for a class of model reference adaptive control systems. To increase the convergence rate of a model following error, an error feedback term is incorporated into the control law.

• 제어로봇시스템학회논문지
• /
• 제15권7호
• /
• pp.711-719
• /
• 2009

This paper presents a design scheme of torque control for wheeled mobile robot(WMR) to asymptotically track the target reference trajectory. By considering the kinematic model of WMR, trajectory tracking control generates the desired tracking trajectory, which is transformed into the command velocity vector for the real WMR to track the target reference trajectory. The dynamic equation of the state error between the target reference trajectory and the desired tracking trajectory is represented by Takagi-Sugeno fuzzy model, and this model is used as the reference model for the real mobile robot error dynamics to follow. The control parameters are updated by adaptive laws that are designed for the error states of the real WMR to asymptotically follow the states of reference error model for the desired tracking trajectory. The proposed control is applied to a typical wheeled mobile robot and simulation studies are carried out to verify the validity and effectiveness of the control scheme.

• Journal of Mechanical Science and Technology
• /
• 제16권6호
• /
• pp.799-809
• /
• 2002

In order to utilize a parallel mechanism as a machine tool component, it is important to estimate the errors of its end-effector due to the uncertainties in parts. This study proposes an error analysis for a new parallel device, a cubic parallel mechanism. For the parallel device, we consider two kinds of errors. One is a static error due to link stiffness and the other is a dynamic error due to clearances in the parts. In this study, we propose a stiffness model for the cubic parallel mechanism under the assumption that the link stiffness is a linear function of the link length. Also, from the fact that the errors of u-joints and spherical joints are changed with the direction of force acting on the link, they are regarded as a part of link errors, and then the error model is derived using forward kinematics. Lastly, both the error models are integrated into the total error, which is analyzed with a test example that the platform moves along a circular path. This analysis can be used in predicting the accuracy of other parallel devices.

• 한국생산제조학회지
• /
• 제9권2호
• /
• pp.102-111
• /
• 2000

Methodology of volumetric error identification and compensation is presented to improve the accuracy of NC machine tools by using a reference artifact and a touch trigger probe. Homogeneous transformation matrix and kinematic chain are used for modeling the geo-metric and thermal errors of a three-axis vertical machining center. The reference artifact is designed and fabricated to identify the model parameters by machine tool metrology. Parameters in the error model are able to be identified and updated by direct measurement of the reference artifact on the machine tool under the actual conditions which include the thermal interactions of error sources. A volumetric error compensation system based on IBM/PC is linked with a FANUC CNC controller to compensate for the identified volumetric error in machining workspace.

• 환경정책연구
• /
• 제3권2호
• /
• pp.89-112
• /
• 2004

This Study aims to demonstrate how much flood vulnerability in urban area changed for the past 32 years by using the panel model. At the same time, this study strives to determine the primary factors and to construct an effective counter-plan by means of empirical research. After selecting research hypotheses based on considerations of issues concerning causes for urban flooding, their relevance is put to the test by conducting empirical research in individual case locations. This research verifies the four research hypotheses by using one-way error component regression model. In conclusion, this research has shown that urban land use and local characteristics act as significant flood determinants, with forests acting to reduce flood dangers. Moreover, constructing embankments can no longer represent a reliable flood control policy. The changes in future flood control policies need to incorporate local characteristics and to minimize natural destruction, so that humans and nature can coexist through environmentally friendly flood management policies.

• 물과 미래
• /
• 제23권1호
• /
• pp.79-87
• /
• 1990

본 연구에서는 회귀모형의 오차분석을 모형오차분석과 표본오차분산으로 분리하므로써 오차분산에 대한 합리적이고도 편의되지 않은 추정량을 제공해 줄 수 있는 일반화 최소자승법을 이용하여 한강 및 낙동강유역의 유량관측점에서 수집된 연최대홍수량 자료를 유역특성 및 강우량 자료와 연관시키는 지역화회귀모형을 개발하였다. 본 모형은 계측지점으로부터 미계측지점으로 수문정보를 전달해주기 위한 수단으로 사용될 수 있다.

• 한국정보통신학회논문지
• /
• 제27권1호
• /
• pp.135-138
• /
• 2023

In this paper, we study real-time error in the context of monitoring a binary information source through a delay system. To derive the average real-time error, we model the delay system as a discrete time Geo/D/1/1 queueing model. Using a discrete time three-dimensional Markov chain with finite state space, we analyze the queueing model. We also perform some numerical analysis on various system parameters: state transition probabilities of binary information source; transmission times; and transmission frequencies. When the state changes of the information source are positively correlated and negatively correlated, we investigate the relationship between transmission time and transmission frequency.