• Journal of Korea Water Resources Association
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• v.43 no.12
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• pp.1039-1050
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• 2010

Relative accuracy of six discharge measurement methods-velocity-area method, rod-float method, ADCP moving-vessel method, ADCP fixed-vessel method, electromagnetic wave surface velocimeter (EWSV), LSPIV- is evaluated by comparing discharges measured by them with dam released discharges. Data from 39 times of concurrent discharge measurement campaigns are analyzed. Except the rod-float method, measured discharges show absolute errors less than 6.2% with dam discharges. When the four methods is evaluated by being compared with discharges measured with the conventional velocity-area method, discharges with electromagnetic wave surface velocimetry shows 7.35% of absolute errors and other three methods shows absolute errors less than 6%. The rod-float method, which shows large discrepancy compared with dam and velocity-area method, need complementary verification.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.2
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• pp.307-316
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• 2019

Development of vegetation in stream channel increases resistance to flow, resulting in increase in river stage upon flood and affecting change in stage-discharge relationship. Vegetation revealed in stream by water level reaching a peak and then declined upon flood is mostly found as prone. Taking an account of flow distribution with the number of vegetation, prone vegetation layer might be at height where discharge rate is zero (0) (Stephan and Guthnecht, 2002). However, there is a tendency that flow rate is overestimated when applying the height of river bed to flow area with no consideration of the height of vegetation layer in flow rate by float measurement. In this study, reliable flow measurement in stream with vegetation was calculated by measuring the height of vegetation layer after flood and excluding the vegetation layer-projected area from the flow area. The result showed the minimum 4.34 % to maximum 10.82 % of flow deviation depending on the scale of discharge. Accordingly, reliable velocity-area methods would be determined if vegetation layer-projected area in stream is considered in flow rate estimation using the flow area during the flood.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.443-447
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• 2005

The SAR measurement system with stationary probes, presented in this paper, can calculate area SAR value based ell the measured 9 electric field data. By converting obtained area SAR to the volume SAR, the results can be acquired in a few seconds. The system can be very useful tool in the stages of handset development for mobile communication as well as in the handset production line because of its rapid SAR measurement. The system showed good linearity characteristics at 835 MHz of 10 $\sim$ 27 dBm input power range.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.3
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• pp.274-279
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• 2008

Roll to roll (R2R) manufacturing process, also known as 'web processing', has been tried for producing electronic devices on a flexible plastic or metal foil. To increase the performance and productivity the R2R process, effective control and on-line supervision for web quality becomes very important. Wrinkle is one of the defects, which is incurred due to compressive stresses. A system for on-line measurement of wrinkle is developed using area scan camera and machine vision laser. The 2D image, obtained by area scan camera, is produced by Gaussian regression method to characterize the wrinkle on a transparent web. The experiment proves that 0.3mm wrinkle height can be measured successfully with 74fps.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.718-721
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• 2005

The purpose of the study is to evaluate the usage of microtremor in estimation of subsurface structure and ground response to ground motion. Ground motion amplification based on site condition of an area is an important parameter for dynamic design. Microtremor cover the characteristics in a low frequency range, while forced vibrations cover them in a high-frequency range. Microtremor consider ground characteristics and offer transfer function in area. To determine the dominant frequency, the passive microtremor measurement is performed and to determine the transfer function of test site, active microtremor measurement is performed. Microtremor measurement in the site is compared with theoretical transfer function calculated from the known structures.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.600-605
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• 2000

The aim of this study is to compare the sound insulation performances of window depending on the measurement methods through the field test and analyze the factors that affect the sound insulation performances. Four measurement methods which are specified in the Koran Standard 2235 and the International Standard 140-5 were selected for the study; the outdoor sound source method which is classified the l000mm method and the 10mm method, the indoor sound source method, and the ISO method. The result of this study is that the sound insulation performance of the windows was the best when measured according to the ISO method and the worst the indoor sound source method. Through the study it was found that the main factors affecting the sound insulation performance of the windows were the correction of the specimen's area and the equivalent sound absorption area of the receiving room.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.129-133
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• 2000

It is reasonable to use the stereo vision and image processing technique to digitize 3D coordinates of grid points and to evaluate surface strains on a sheet metal parts. However this method has its intrinsic problems such as the difficulty in enhancement of bad images inevitable error due to digital image resolution of camera and frame grabber unreliability of strains and thickness evaluated from coarse grid on the corner area with large curvature and the limitation of the area that can be measured at a time. Therefore it is still hard to measure strain distribution over the entire surface of a medium,- or large-sized stamped part at a time even by using an automated strain measurement system. In this study the curvature correction algorithm based on the grid refinement and the geometry assembling algorithm based on the global error minimization (GEM) scheme are suggested. Several applications are presented to show the reliability and efficiency of these algorithms.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.8 no.1
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• pp.57-62
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• 1994

In this paper, a system for measuring of treeing degradation in organic dielectric material by using image processing technics, is discussed. Traditionally, treeing is measured by visual method. It made difficulty to understanding for features and changes in the configlEation of the tree growth. Using image processing system, it is made to describe the characters of the tree growth, specially length of tree and area of treeing degradation. From this image processing and visual measurement, the similar results were made, an automatic measurement system was made for configuration of the tree growth.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8B
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• pp.1456-1463
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• 1999

This paper describes the measurement system of antenna factor using standard antenna method in OATS(Open Area Test Site) of KRISS(Korea Research Institute of Standards and Science) and methods for reducing an environmental noise affecting antenna factor. The range of measurement frequency is 30 - 1000 MHz, all control and data acquisition were done by computer automatically. Measurement results of antenna factors are presented, total uncertainty of antenna factor is $\pm$1 dB.

• Journal of the Semiconductor & Display Technology
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• v.17 no.4
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• pp.86-90
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• 2018

Standards related to express the non-flatness of a wafer are reviewed and discussed, for example, bow, warp, and sori. Novel wafer warpage measurement method is proposed for 3D stacked IC application. The new way measures heat transfer from a heater to a wafer, which is a function of the contact area between these two surfaces and in turn, this contact area depends on the wafer warpage. Measurement options such as heating from room temperature and cooling from high temperature were experimentally examined. The heating method was found to be sensitive to environmental conditions. The cooling technique showed more robust and repeatable results and the further investigation for the optimal cooling condition is underway.