• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.235.1-235.1
• /
• 2014

Precise measurement of plasma parameters including density and temperature is the most essential part for understanding plasma characteristics. To persue more accurate measurement, it is very important to understand the intrinsic error of the measurement method. In this paper, we performed the plasma measurement with different method; langmuire probe and cutoff probe. Both measurement technology are known to be exactly correlate with etch other. We conducted the four set of same experiments process by diffrent persons to observe the intrinsic error based on measurement tools. As a result, the cutoff probe is relatively reliable then the Langmuir probe. This difference is analyzed to be intrinsic since it cames from the inevitable error such as manufacturing of probe tip. From this study, we sure that it is good decision to choose cutoff probe as repeatable measurement independent with intrinsic human factor.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1996.10a
• /
• pp.85-92
• /
• 1996

The Measurement method of the plastic strain ratio is various in Automotive sheet steel. In this paper, the measurement of the plastic strain are used two different methods, ASTM E 517 method and the automatic strain measurement tensile specimen during the tensile test, and compared the plastic strain ratios from the two methods. The experimental results showed that the measured plastic strain ratios from the automatic strain measurement method are coincide with that from the ASTM E 517 standard measurement in various specimens. Therefore, automatic strain measurement method by two extensometers shows good accuracy. Also, the strain dependance of plastic strain ratios could be recorded by the computer continuously and anisotropy of the strength coefficient, K, and strain hardening exponent, n ,could be compared with each direction automatically through the use of automatic strain measurement system.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.8
• /
• pp.113-121
• /
• 1999

It is necessary to calibrate measurement systems to enhance its measurement accuracy. The visual sensing system that is presented in our previous work has to be calibrated, too. It is a multiple mirror system for three-dimensional measurement, which is composed of a camera and a series of mirrors. It is important to calibrate the positions and orientations of the mirrors relative to the camera because they have direct influence on the relationship between the image plane and the task space. This paper presents the calibration method for the visual sensing system. To confirm the measurement performance of the implemented system. its measurement accuracy in measuring the locations in three-dimensional space is investigated. A series of experiments for measuring the locations of the circle-shaped marks are performed. Experimental results show that the sensing system can be effectively used for three-dimensional measurement.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.10
• /
• pp.172-181
• /
• 1999

The objective of this research is to develop a measurement error model for sculptured surfaces in On-Machine Measurement (OMM) process based on a closed-loop configuration. The geometric error model of each axis of a vertical CNC Machining center is derived using a 4${\times}$4 homogeneous transformation matrix. The ideal locations of a touch-type probe for the scupltured surface measurement are calculated from the parametric surface representation and X-, Y- directional geometric errors of the machine. Also, the actual coordinates of the probe are calculated by considering the pre-travel variation of a probe and Z-directional geometric errors. Then, the step-by-step measurement error analysis method is suggested based on a closed-loop configuration of the machining center including workpiece and probe errors. The simulation study shows the simplicity and effectiveness of the proposed error modeling strategy.

• 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.

• International Journal of Reliability and Applications
• /
• v.9 no.1
• /
• pp.7-15
• /
• 2008

The dimensional measurement equipment, such as Coordinate Measurement Machine (CMM), Optical Coordinate Measurement Machine (OCMM), and Checking Fixture (CF), take multiple dimensional measurements for each part in an automobile industry. Measurements are also recorded under different measurement systems to see if the responses differ significantly over these systems. Each measurement system (CMM, OCMM, and CF) will be considered as different treatments. This set-up provides massive amounts of process data which are multivariate in nature. Therefore, the multivariate statistical analysis is required to analyze data that are dependent on each other. This research provides step by step methodology for the evaluation procedure of the compatibility of measurement systems and clarify a systematic analyzation among the different measurement system's compatibility followed by number of case studies for each methodologies provided.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.16 no.6
• /
• pp.797-802
• /
• 2013

In this paper, using the mass/CG measurement equipment and the MOI measurement equipment developed in-house, Pitch MOI and Roll MOI of test specimen were measured and measurement uncertainties on MOI were studied. The possible factors of the measurement uncertainty that could affect accuracy of MOI measurement were mass, spring, frequency, and length measurement-related elements. The each combined standard uncertainty of pitch MOI and roll MOI was estimated from the uncertainties of the above various factors.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.7
• /
• pp.99-104
• /
• 2003

A precision displacement measurement system of 3-DOF micro motions is proposed in this paper. The measurement system is composed of two diode lasers, two quadratic PSDs, two beam splitters and a sphere whose surface is highly reflective. In this measurement system, the sphere reflector is mounted on the platform of positioning devices whose 3-DOF translational motions are to be measured, and the sensitive areas of two PSDs are oriented toward the center point of the sphere reflector. Each laser beam emitted from two diode laser sources is reflected at the surface of sphere and arrives at two PSDs. Each PSD serves as a 2-dimensional sensor, providing the information on the 3-dimensional position of the sphere. In this paper, we model the relationship between the outputs of two PSDs and 3-DOF translational motions of the sphere mounted on the object. Based on a deduced measurement model, we perform measurement simulation and evaluate the performance of the proposed measurement system: linearity, sensitivity, and measurement error. The simulation results show that the proposed measurement system can be valid means of precision displacement measurement of 3-dimensional micro motions.

• Journal of Korea Technology Innovation Society
• /
• v.5 no.2
• /
• pp.245-256
• /
• 2002

Measurement standards, as being widely recognized, is necessary for national economic development and advanced industrialization. Also measurement standards give reliability and fair trade to the producers and consumers. Macro-effect of measurement standards using estimation of cost function has four effects: 1) value-added causing effect, 2) effect of employment, 3) reduction effect transaction cost, 4) reduction effect defect rates. In this study, to investigate the impacts between specific and the other industries, we used I-O Table of Korea Bank. The relation between the value-added produced by original production factors and final use is determined through production level, and the relation can be investigated with production causing coefficient matrix. In this study, it was showed that the measurement standards investments including measurement only man power of industries were increased from 1995 rapidly. The establishment and maintenance of measurement standards contributes to reduce the defect rate of products in production process and improve the confidence of the product quality. The results from this study show that measurement technology contributes to improve quality, decrease defect rate, improve production process, develope new products, reduce prime cost and increase the consumer's confidence on the firms. Since these results indicate that measurement standards are very important in the point of their vast contribution, we hope our findings can contribute to encourage measurement activities in industries.

• The Journal of Korean Physical Therapy
• /
• v.29 no.3
• /
• pp.145-151
• /
• 2017

Purpose: The purpose of this study was to investigate the validity and reliability of the measurement of shoulder joint motions using an inertial measurement unit (IMU). Methods: For this study, 33 participants (32 females and 1 male) were recruited. The subjects were passively positioned with the shoulder placed at specific angles using a goniometer (shoulder flexion $0^{\circ}-170^{\circ}$, abduction $0^{\circ}-170^{\circ}$, external rotation $0^{\circ}-90^{\circ}$, and internal rotation $0^{\circ}-60^{\circ}$ angles). Kinematic data on the shoulder joints were simultaneously obtained using IMU three-dimensional (3D) angular measurement (MyoMotion) and photographic measurement. Test-retest reliability and concurrent validity were examined. Results: The MyoMotion system provided good to very good relative reliability with small standard error of measurement (SEM) and minimal detectable change (MDC) values from all three planes. It also presented acceptable validity, except for some of shoulder flexion, shoulder external rotation, and shoulder abduction. There was a trend for the shoulder joint measurements to be underestimated using the IMU 3D angular measurement system compared to the goniometer and photo methods in all planes. Conclusion: The IMU 3D angular measurement provided a reliable measurement and presented acceptable validity. However, it showed relatively low accuracy in some shoulder positions. Therefore, using the MyoMotion measurement system to assess shoulder joint angles would be recommended only with careful consideration and supervision in all situations.