• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.2
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• pp.112-119
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• 2011

This paper is concerned with the measurement of static and dynamic displacement by image processing(IP) and study for prediction method of velocity and acceleration. To measure the displacement visually, the measurement system consists of a telephoto zoom camera, CCD(charge coupled device) image device and a computer. The specific target on the white board is used to calculate the displacement of the structure. The captured image is then converted into a pixel-based data and then analyzed numerically. The limitation of the system depends on the image capturing speed and the pixel-size of image. In this paper, we developed for the displacement measurement using the image processing method. The proposed method enables us to measure the vibration displacement, velocity and acceleration directly without any contact. The current resolution for the displacement measurement can be seen from the results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.1043-1047
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• 2003

Most of the measurement and the evaluation of hand-transmitted vibration have been performed by using a small size single axis accelerometer between the handle and the hand palm or a three axis accelerometer attached on an adapter outside the hand(indirect measurement). It is most desirable for the correct evaluation of hand-transmitted vibration form the power tool handle to measure the acceleration between the handle surface and the hand palm in the three axis(direct measurement) as recommended in ISO 5349-1. In the study three axes acceleration measurement device was developed of which the thickness was less than 7mm so that it can be placed between the handle and the palm without any inconvenience during the measurement. To verify the performance of the developed device, measured acceleration by the two methods, direct and indirect, were compared in the study.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.4
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• pp.57-63
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• 2003

Machining information such as form accuracy and surface roughness is an important factor for manufacturing precise parts. To this regard, OMM (On the Machine Measurement) has been researched for last several decades to alternate CMM (Coordinate Measurement Machine) process. In this research, the OMM system with a laser displacement sensor was developed for measuring form accuracy and surface roughness of the machined workpiece on the machine tool. The surface roughness was estimated comparing the sensory signal with the reference data measured from master specimen. Also, form accuracy was determined from the moving averaged raw data. In addition, the geometric error map constructed beforehand using the geometric errors of the machine tool was used to compensate the obtained form accuracy. The overall performance was compared with CMM result, and verified the feasibility of the measurement system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.5
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• pp.525-533
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• 1997

A nondestructive moisture measurement technique has been applied to improve the previous moisture measurement method in the building research. The experiment was done in free space using horns since it is the key element for continuous and non-destructive measurement. For this purpose a microwave bridge type analyzer at the frequency of 9.5 GHz was used to determine the moisture content of sands in the range of 1~12%. From this, the representative calibration curves were obtained. This shows that moisture measurement technique using microwave is applicabe to the measurement of moisture in non-metallic materials such as coal, pulp, foods, building materials, etc.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.50
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• pp.55-63
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• 1999

Past studies on economic control charts for controlling process means assumed that the measures of a quality characteristic do not have measurement error. In practice, however, this assumption is frequently violated. In this paper, the economic design models of three control charts(Xbar control chart, Xbar control chart with warning limits, and CUSUM control chart) for controlling process means are developed on the assumption that the measures can have measurement error. The effects of measurement error on the process control cost and design parameters of three economic control charts are examined. According to the experiments done in this study, when measurement error exists, the economic CUSUM control chart has lower process control cost in comparison with two other control charts. When measurement error becomes larger, both the sample size and the sampling interval increase while the control limits decrease.

• KIEE International Transaction on Systems and Control
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• v.2D no.2
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• pp.97-107
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• 2002

In this paper, we propose the concept of orthonormalized compressed measurement for the stability analysis of discrete linear time-varying Kalman filters. Unlike previous studies that deal with the homogeneous portion of Kalman filters, the proposed Lyapunov method directly deals with the stochastically-driven system. The orthonorrmalized compressed measurement provides information on the a priori state estimate of the Kalman filter at the k-th step that is propagated from the a posteriori state estimate at the previous block of time. Since the complex multiple-step propagations of a candidate Lyapunov function with process and measurement noises can be simplified to a one-step Lyapunov propagation by the orthonormalized compressed measurement, a stochastic radius of attraction can be derived that would be impractically difficult to obtain by the conventional multiple-step Lyapunov method.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.5
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• pp.531-542
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• 2007

Simultaneous measurement technique for temperature and velocity fields near a heated solid body has been constructed. The measurement system consists of a 3-late CCD color camera, a color image grabber, a 1ighting system, a host computer and a software for the whole quantification process. Thermo Chromic Liquid Crystals (TCLC) was used as temperature sensors. A neural network was used to get a calibration curve between the temperature and the color change of the TCLC in order to enhance the dynamic range of temperature measurement. The velocity field measurement was attained by the use of the fray-level images taken for the flow field, and by introducing the cross-correlation technique. The temperature and the velocity fields of the forced and the natural convective flows neat the surface of a cartridge heater were measured simultaneously with the constructed measurement system.

• Journal of Biomedical Engineering Research
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• v.16 no.1
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• pp.85-94
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• 1995

We have developed MSPF (measurement system for physical fitness) which measures physical strength and body dimensions. This system has two main features, one is an automatic measurement of physical fitness, and the other is reducement of reading and writing errors caused by human during measurement. Using the MSPF, total ten items can be measured such as weight, height, sit up, push up,. etc. Since the system which have objectification and high precision has been needed, we used a memory card. By using this, it was easy to save and archive data by computer.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.3
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• pp.187-193
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• 2003

This paper presents an on-machine measurement method of flatness error fur surface machining processes. There are two kinds of on-machine measurement methods available to measure flatness errors in workpieces: i.e., surface scanning method and sensor scanning method. However, motion errors are often engaged in both methods. This paper proposes an idea to realize a measurement system of flatness errors and its rigorous application for estimation of motion errors of the positioning system. The measurement system is made by modifying the straightness measurement system, which consists of a laser, a CCD camera and processing system, a sensor head, and some optical units. The sensor head is composed of a retroreflector, a ball and ball socket, a linear motion guide unit and adjustable arms. The experimental .results show that the proposed method is useful to identify flatness errors of machined workpieces as well as motion errors of positioning systems.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.922-925
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• 2005

This article describes a FM modulation algorithm to increase the measurement speed by increasing the beat frequency of the laser without acousto-optic modulator(AOM) in the heterodyne laser interferometer. The proposed algorithm can increase the beat frequency of the heterodyne laser which limit the measurement speed by adjusting a carrier frequency through electronic circuit, while AOM is used to shift the frequency of the heterodyne laser in conventional method. Electronic circuit is constructed to modulate the signals from a laser interferometer and a waveform generator. The brier analysis, the measurement scheme of the system, and the experimental results using a Zeeman-stabilized He-Ne laser are presented. They demonstrate that the proposed algorithm is proven to enhance the measurement speed limit by increasing the beat frequency of the heterodyne laser.