• Title/Summary/Keyword: Test Accuracy

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A Study on the Modeling Method of Missile Fin Aerodynamic Coefficient using Wind Tunnel Test and CFD (풍동시험과 CFD 해석 결과를 반영한 유도무기 조종날개 공력계수 모델링 기법 연구)

  • Yim, Kyung Jin
    • Journal of the Korea Institute of Military Science and Technology
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    • v.22 no.3
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    • pp.360-368
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    • 2019
  • A study on aerodynamic modeling was performed to predict the hinge moments required for initial design of missile. Fin aerodynamic coefficients were modeled using the equivalent angle of attack method based on the wind tunnel test. In addition, CFD analysis was performed to calculate the dynamic pressure around the body and improve the accuracy of aerodynamic coefficients. The aerodynamic coefficient accuracy was verified by comparisons of the coefficient acquired from wind tunnel test and prediction of flow conditions, not involved in the model built-up. It was confirmed that fin aerodynamic coefficients can be predicted effectively by using the proposed method.

Prediction of 305 Days Milk Production from Early Records in Dairy Cattle Using an Empirical Bayes Method

  • Pereira, J.A.C.;Suzuki, M.;Hagiya, K.
    • Asian-Australasian Journal of Animal Sciences
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    • v.14 no.11
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    • pp.1511-1515
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    • 2001
  • A prediction of 305 d milk production from early records using an empirical Bayes method (EBM) was performed. The EBM was compared with the best predicted estimation (BPE), test interval method (TIM), and the linearized Wood's model (LWM). Daily milk yields were obtained from 606 first lactation Japanese Holstein cows in three herds. From each file of 305 daily records, 10 random test day records with an interval of approximately one month were taken. The accuracies of these methods were compared using the absolute difference (AD) and the standard deviation (SD) of the differences between the actual and the estimated 305 d milk production. The results showed that in the early stage of the lactation, EBM was superior in obtaining the prediction with high accuracy. When all the herds were analyzed jointly, the AD during the first 5 test day records were on average 373, 590, 917 and 1,042 kg for EBM, BPE, TIM, and LWM, respectively. Corresponding SD for EBM, BPE, TIM, and LWM were on average 488, 733, 747 and 1,605 kg. When the herds were analyzed separately, the EBM predictions retained high accuracy. When more information on the actual lactation was added to the prediction, TIM and LWM gradually achieved better accuracies. Finally, in the last period of the lactation, the accuracy of both of the methods exceeded EBM and BPM. The AD for the last 2 samples analyzing all the herds jointly were on average 141, 142, 164, and 214 kg for LWM, TIM, EBM, and BPE, respectively. In the current practices of collecting monthly records, early prediction of future milk production may be more accurate using EBM. Alternatively, if enough information of the actual lactation is accumulated, TIM may obtain better accuracy in the latter stage of lactation.

The Organization of Rotational Accuracy Measurement System of NC Lathe Spindle (NC 선반 주축의 회전정도 측정 시스템의 구성)

  • Kim, Young-Seuk
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.14 no.5
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    • pp.21-26
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    • 2005
  • It is important to measure the rotational accuracy of NC lathe spindle as it affects to the qualities of all machines machined by the NC lathe using in industries. The bad rotational accuracy of NC lathe spindle are caused mainly by wearness of the spindle in using and quality of spindle when machining and using low level bearings. It occurs especially in case of NC lathes because the cutting force acting to work-piece act on one side to the spindle not to both sides symmetrically. Therefore in this study, constructing experimental appratus for measuring of rotational accuracy by using eddy current type gap sensors, converters, screw terminal, data acquisition board inserted in computer and software f3r data acquisition, DT VEE ver. 5.0 and then error data acquired in the rotational accuracy test of NC lathe spindle are analysed in plots and statistical treatments.

Measuring of Rotational Accuracy of Lathe Spindle (선반 주축의 회전운동 정도 측정)

  • Kim, Young-Seuk
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.16 no.6
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    • pp.43-48
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    • 2007
  • It is important to measure the rotational accuracy of lathe spindle as it affects to the qualities of all machines machined by the lathe using in industries. The bad rotational accuracy of lathe spindle are caused mainly by wearness of the spindle in using and quality of spindle when machining and using low level bearings. It occurs especially in case of lathes because the cutting force acting to work-piece act on one side to the spindle not to both sides symmetrically. Therefore in this study, constructing experimental apparatus for measuring of rotational accuracy by using eddy current type gap sensors AEC5706PS and sensors, s-06LN, data acquisition board DT9834(USB type) and software for data acquisition, DT Measure Foundry ver. 4.0.7 etc., error data acquired in the rotational accuracy test of lathe spindle are analysed in plots and statistical treatments.

Alternative accuracy for multiple ROC analysis

  • Hong, Chong Sun;Wu, Zhi Qiang
    • Journal of the Korean Data and Information Science Society
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    • v.25 no.6
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    • pp.1521-1530
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    • 2014
  • The ROC analysis is considered for multiple class diagnosis. There exist many criteria to find optimal thresholds and measure the accuracy of diagnostic tests for k dimensional ROC analysis. In this paper, we proposed a diagnostic accuracy measure called the correct classification simple rate, which is defined as the summation of true rates for each classification distribution and expressed as a function of summation of sequential true rates for two consecutive distributions. This measure does not weight accuracy across categories by the category prevalence and is comparable across populations for multiple class diagnosis. It is found that this accuracy measure does not only have a relationship with Kolmogorov - Smirnov statistics, but also can be represented as a linear function of some optimal threshold criteria. With these facts, the suggested measure could be applied to test for comparing multiple distributions.

A Study of ECG Based Cardiac Diseases Diagnoses (심전도 신호를 이용한 심장 질환 진단에 관한 연구)

  • Kim, Hyun-Dong;Yoon, Jae-Bok;Kim, Hyun-Dong;Kim, Tae-Seon
    • Proceedings of the KIEE Conference
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    • 2004.11c
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    • pp.328-330
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    • 2004
  • In this paper, ECG based cardiac disease diagnosis models are developed. Conventionally, ECG monitoring equipments can only measure and store ECG signals and they always require medical doctor's diagnosis actions which are not desirable for continuous ambulatory monitoring and diagnosis healthcare systems. In this paper, two kinds of neural based self cardiac disease diagnosis engines are developed and tested for four kinds of diseases, sinus bradycardia, sinus tachycardia, left bundle branch block and right bundle branch block. For diagnosis engines, error backpropagation neural network (BP) and probabilistic neural network (PNN) were applied. Five signal features including heart rate, QRS interval, PR interval, QT interval, and T wave types were selected for diagnosis characteristics. To show the validity of proposed diagnosis engine, MIT-BIH database were used to test. Test results showed that BP based diagnosis engine has 71% of diagnosis accuracy which is superior to accuracy of PNN based diagnosis engine. However, PNN based diagnosis engine showed superior diagnosis accuracy for complex-disease diagnoses than BP based diagnosis engine.

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Comparison of Reliability Estimation Methods for One-shot Systems Using Accelerated Life Tests (가속수명시험을 이용한 원샷 시스템의 신뢰도 추정방법 비교)

  • Son, Young-Kap;Jang, Hyun-Jung
    • Journal of Korean Institute of Industrial Engineers
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    • v.36 no.4
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    • pp.212-218
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    • 2010
  • This paper shows accuracy comparison results of reliability estimation methods for one-shot systems with respect to sample sizes. To compare accuracy in reliability estimation methods, quantal-response data, characterizing one-shot systems, were simulated using failure times of LED obtained through the accelerated life test, and then the true reliability over time was evaluated using the failure times. The simulated quantal-response data were used to estimate the true reliability through applying reliability estimation methods in open literature. Accuracy of each reliability estimation method was compared in terms of both SSE (Sum of Squared Error) and MSE (Mean Squared Error), and then estimation trend for each method is found. Feasible bounds which true reliability would exist within were estimated through applying the found trends to quantal-response data set of a real weapon system.

A Study on the Thermal Behaviro of Machine Tool Spindle System (공작기계 주축계 열적거동에 관한 연구)

  • 김종관
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.8 no.1
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    • pp.28-34
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    • 1999
  • According to the development of tool material and the improvement of machinability of cutting material like aluminium alloy, the higher spindle speed is needed. However, the higher speed causes the heat generation of bearings, the deformation of spindle unit parts, and the rotational accuracy of spindle to be worse. Therefore, it is essential to analyze and control the heat generation and the thermal behavior of spindle unit in order to have higher speed and better rotational accuracy. This paper shows the analogy between the analyzation of heat generation and thermal behavior of high speed spindle system by finite element method and the test results of actual temperature rise through running test, and shows the necessity of cooling the spindle and inner ring side of bearings for the thermal balance of high speed spindle system.

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Development of a Linear Motor Dynamometer for Positioning Control Performance Test (Linear모터의 위치 제어 성능 시험을 위한 Dynamometer 개발)

  • Roh Chang-Yul;Rho Myung-Hwan;Kim Ju-Kyung;Park Jong-Jin;Lee Eung-Suk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.5 s.248
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    • pp.609-614
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    • 2006
  • Recently linear motor has been used mainly for high speed feeding performance of machine tools. The advantages of linear motor are not only high speed but high accuracy, because it is not required the coupling and ballscrew for converting rotary to liner motion. Before applying in different moving system, the dynamometer is necessary to test the performance. In Korea, the linear motor is producing in a couple of company However, the liner motor dynamometer is not commercialized yet, like as rotary motor dynamometer. In this paper, a linear motor dynamometer is designed and manufactured using a MR damper. The dynamometer system developed in this study could be used for testing the positioning accuracy fur different loading conditions, traction forces, dynamic performance and so on.

A structural study on mold EMBO equipment to minimize the influence on the bottom dead center displacement of precision high-speed press (정밀고속 PRESS 하사점 변위량에 영향을 최소화 하는 금형 EMBO 장치에 관한 구조 연구)

  • Kim, Seung-Soo
    • Design & Manufacturing
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    • v.10 no.3
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    • pp.46-50
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    • 2016
  • Laminate products for motor core are developed with a structure in which the importance of quality level and clamping force is influenced by the recent performance and safety of the product. It has been confirmed that the accuracy of the mold is emphasized, and that the accuracy of the tightening force produced by the stacked product for the motor core is greatly influenced by the change in the bottom dead center displacement of the aged high speed press. The reason why setting the mold, and test the effect of bottom dead center of high speed press is to improve product pull force in embossing process at mold. We have applied the system to minimize the effect on the damping displacement under the dynamical degree of the equipment by applying the emboss complement device which can test the influence and complement in the process.