• Title, Summary, Keyword: accuracy

Search Result 27,592, Processing Time 0.075 seconds

A Study on the Test Workpiece for Accuracy Evaluation of 5-Axis Machine Tool (5축 공작기계 정밀도 평가를 위한 표준 공작물에 관한 연구)

  • Youn, Jae-Woong;Kim, Ki-Hwan;Park, Jong Tak
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.31 no.5
    • /
    • pp.431-439
    • /
    • 2014
  • Recently, a demand for precision 5-axis machine tools is significantly increasing, and the maintenance of machine tool accuracy becomes more important. it is very difficult to evaluate to accuracy of 5-axis M/C in the production site since it needs expensive measuring equipment and skilled engineer. On the other hand, evaluation items of 5-axis M/C are not systematically organized in the existing KS and ISO standards. In this study, the evaluation items for 5-axis M/C were derived systematically and a test workpiece was developed to evaluate the machine tool accuracy more easily. The error sources of machine tool can be estimated by machining and measuring of the test workpiece. The correlation between the machine tool accuracy and the accuracy of machined test workpiece was analyzed. As a result, the accuracy of machined test workpiece represented the accuracy of machine tool and the error sources very effectively.

A Study on Accuracy Estimation of Service Model by Cross-validation and Pattern Matching

  • Cho, Seongsoo;Shrestha, Bhanu
    • International journal of advanced smart convergence
    • /
    • v.6 no.3
    • /
    • pp.17-21
    • /
    • 2017
  • In this paper, the service execution accuracy was compared by ontology based rule inference method and machine learning method, and the amount of data at the point when the service execution accuracy of the machine learning method becomes equal to the service execution accuracy of the rule inference was found. The rule inference, which measures service execution accuracy and service execution accuracy using accumulated data and pattern matching on service results. And then machine learning method measures service execution accuracy using cross validation data. After creating a confusion matrix and measuring the accuracy of each service execution, the inference algorithm can be selected from the results.

Development of association rule threshold by balancing of relative rule accuracy (상대적 규칙 정확도의 균형화에 의한 연관성 측도의 개발)

  • Park, Hee Chang
    • Journal of the Korean Data and Information Science Society
    • /
    • v.25 no.6
    • /
    • pp.1345-1352
    • /
    • 2014
  • Data mining is the representative methodology to obtain meaningful information in the era of big data.By Wikipedia, association rule learning is a popular and well researched method for discovering interesting relationship between itemsets in large databases using association thresholds. It is intended to identify strong rules discovered in databases using different interestingness measures. Unlike general association rule, inverse association rule mining finds the rules that a special item does not occur if an item does not occur. If two types of association rule can be simultaneously considered, we can obtain the marketing information for some related products as well as the information of specific product marketing. In this paper, we propose a balanced attributable relative accuracy applicable to these association rule techniques, and then check the three conditions of interestingness measures by Piatetsky-Shapiro (1991). The comparative studies with rule accuracy, relative accuracy, attributable relative accuracy, and balanced attributable relative accuracy are shown by numerical example. The results show that balanced attributable relative accuracy is better than any other accuracy measures.

Development and Comparative Analysis of Mapping Quality Prediction Technology Using Orientation Parameters Processed in UAV Software (무인기 소프트웨어에서 처리된 표정요소를 이용한 도화품질 예측기술 개발 및 비교분석)

  • Lim, Pyung-Chae;Son, Jonghwan;Kim, Taejung
    • Korean Journal of Remote Sensing
    • /
    • v.35 no.6_1
    • /
    • pp.895-905
    • /
    • 2019
  • Commercial Unmanned Aerial Vehicle (UAV) image processing software products currently used in the industry provides camera calibration information and block bundle adjustment accuracy. However, they provide mapping accuracy achievable out of input UAV images. In this paper, the quality of mapping is calculated by using orientation parameters from UAV image processing software. We apply the orientation parameters to the digital photogrammetric workstation (DPW) for verifying the reliability of the mapping quality calculated. The quality of mapping accuracy was defined as three types of accuracy: Y-parallax, relative model and absolute model accuracy. The Y-parallax is an accuracy capable of determining stereo viewing between stereo pairs. The Relative model accuracy is the relative bundle adjustment accuracy between stereo pairs on the model coordinates system. The absolute model accuracy is the bundle adjustment accuracy on the absolute coordinate system. For the experimental data, we used 723 images of GSD 5 cm obtained from the rotary wing UAV over an urban area and analyzed the accuracy of mapping quality. The quality of the relative model accuracy predicted by the proposed technique and the maximum error observed from the DPW showed precise results with less than 0.11 m. Similarly, the maximum error of the absolute model accuracy predicted by the proposed technique was less than 0.16 m.

The Accuracy analysis of a RFID-based Positioning System with Kalman-filter (칼만필터를 적용한 RFID-기반 위치결정 시스템의 정확도 분석)

  • Heo, Joon;Kim, Jung-Hwan;Sohn, Hong-Gyoo;Yun, Kong-Hyun
    • Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
    • /
    • /
    • pp.447-450
    • /
    • 2007
  • Positioning technology for moving object is an important and essential component of ubiquitous. Also RFID(Radio Frequency IDentification) is a core technology of ubiquitous wireless communication. In this study we adapted kalman-filter theory to RFID-based Positioning System in order to trace a time-variant moving object and verify the positioning accuracy using RMSE (Roong technology for moving object is an important and essential component of ubiquitous Mean Square Error). The purpose of this study is to verify an effect of kalman-filter on the positioning accuracy and to analyze what does each design factor have an effect on the positioning accuracy by means of simulations and to suggest a standard of optimal design factor of a RFID-based Positioning System. From the results of simulations, Kalman-filer improved the positioning accuracy remarkably; the detection range of RFID tag is not a determining factor. The smaller standard deviation of detection range improves the positioning accuracy. However it accompanies a smaller fluctuation of the positioning accuracy. The larger detection rate of RFID tag yields the smaller fluctuation in the positioning accuracy and has more stable system and improves the positioning accuracy;

  • PDF

The Effect of firm-specifics on forecast accuracy: The case of IPO firms in Korea (코스닥 신규상장 기업의 특성에 따른 재무분석가의 이익예측력에 관한 연구)

  • Jeon, Seong il;Lee, Ki se
    • Knowledge Management Research
    • /
    • v.13 no.5
    • /
    • pp.1-13
    • /
    • 2012
  • This study investigates whether firm-specifics affect forecast accuracy using a sample of IPO firms in Korea. The forecasts accuracy can be differentiated depending on firm specifics. This study uses the foreign investor, intangible asset and patents as firm specifics. The analysts are divided into two groups by firm-specifies(foreign investors ratio of low and high, intangible asset ratio of low and high, patents of acquisition) and also examine the degree of analysts's forecast accuracy over the two groups. and examined the degree of the analysts' forecast accuracy over the two groups. The sample is composed of 460 IPO (Initial Public Offering) firms listed on the KOSDAQ (Korean Securities Dealers Automated Quotations) for the period from 2001 to 2009. The analysts' forecast accuracy is much higher in the group of high foreign investor but is lower in the group of high intangible assets and patents. Also, the group of high foreign investors respectively interacts with group of high intangible assets ratio and group of patents of acquisition. In result, The analysts' forecast accuracy is higher because foreign investor is decreased information asymmetry. This study compares suggests that patents may be helpful for predicting forecast accuracy.

  • PDF

Dysfunction of Time Perception in Children and Adolescents with Attention-Deficit Hyperactivity Disorder

  • Shin, Dong-Won;Lim, Se-Won;Shin, Young-Chul;Oh, Kang-Seob;Kim, Eun-Jin;Kwon, Yun-Young
    • Journal of the Korean Academy of Child and Adolescent Psychiatry
    • /
    • v.27 no.1
    • /
    • pp.48-55
    • /
    • 2016
  • Objectives: Children with attention-deficit hyperactivity disorder (ADHD) may have deficits in time perception, as assessed by the time estimation task and the time reproduction task, however its age-related trajectory is not yet determined. Therefore we examined the correlation between accuracy of time perception tasks and age, and the association between accuracy of estimation tasks and reproduction tasks. Methods: Sixty-three patients with ADHD, aged 8 to 18 years tested the tasks for five time durations (2, 4, 12, 45, and 60 seconds). Accuracy of tasks was assumed differences (absolute values) between raw results of tasks and original time durations. Spearman's correlation analysis was performed to determine correlation between accuracy of time perception tasks and age. Multivariate regression was used to determine the association of accuracy of estimation tasks with accuracy of reproduction tasks. Results: Age showed correlation with accuracy of estimation tasks, but not with that of reproduction tasks. We observed that the higher the accuracy in 12, 45, and 60 seconds duration time reproduction, the higher the accuracy in longer seconds duration time estimation. Conclusion: Age was correlated with time estimation accuracy whereas there was no impact on time reproduction accuracy. Association of each of the two time perception tasks, particularly in longer time duration, suggested specific impairments in time perception.

A Sudy on the Ealuation of Rtational Acuracy of Hgh Seed Sindle (고속주축의 회전정밀도 성능평가에 관한 연구)

  • 김종관;이중기
    • Journal of KSNVE
    • /
    • v.5 no.4
    • /
    • pp.483-492
    • /
    • 1995
  • For evaluation of rotational accuracy performance of high speed machine tool spindle system, the characteristics of main spindle and tool motion behavior are presented by means of three point accuracy testing method. The results of experiments and analyses are as follows: (1) The high speed spindle rotational accuracy can be evaluated by the combination of the spindle and tool motion behavior. (2) The spindle motion behavior increases up to more that 4 times the tool motion behavior. (3) For the influence of oil viscosity on spindle and tool taper application, 32 cSt of oil viscosity showed the most satisfactory result for rotational accuracy. (4) In order to improve the rotational accuracy of high speed machine tool spindle system, it is needed to reduce the combination error. This can be achieved by improving the working accuracy and supplying the proper lubrication with contact area at the spindle and tool.

  • PDF

A Study on Measurement Accuracy of Theodolite System( I ) - A Measurement Accuracy According to a Theodolite Collimations Distance (데오도라이트 시스템의 측정 정확도에 대한 연구( I ) - 데오도라이트 시준 거리에 따른 측정 정확도)

  • 윤용식;이동주
    • Transactions of the Korean Society of Machine Tool Engineers
    • /
    • v.13 no.2
    • /
    • pp.61-68
    • /
    • 2004
  • A non-contact precision measurement system is a theodolite system, a laser tacker and a photogrammetry system etc. Nowadays, the system reaches to a limit of measurement accuracy required from industrial product of middle and large scale. The one of the solutions for this problem is to maximize the accuracy of the existing measurement system. According to it we performed the study far a measurement accuracy of theodolite system when the distance between two theodolites is changed 1m to 5m. We could blow that the changes of distance affect the measurement accuracy of theodolite system and that the maximum measurement accuracy is $\pm$ 0.02 mm on theodolite distance 3∼4 m.

Measurement of Axis Squireness by using Reversal Method (반전법을 이용한 축 직각도 측정방법)

  • Lee C.W.;Song J.Y.;Ha T.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • /
    • pp.436-439
    • /
    • 2005
  • In general a square master and a dial gauge are used to measure the axis squareness on the spot. This method is a comparison measurement and its accuracy depends on the square accuracy wholly. Therefore the accuracy of a square master is very important and it is impossible that the accuracy of a square measurement is superior to the accuracy of a square master. In this paper, the new method of square measurement is proposed for measuring square without a square master and easily. This method is an absolute measurement by using a reversal method and can be used to measurement the accuracy of a square master.

  • PDF