• Journal of the Korean Society for Precision Engineering
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• v.16 no.8
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• pp.16-22
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• 1999

In this paper, an efficient algorithm for estimating real edge locations to subpixel values is described. Digital images are acquired by projection into image plane and sampling process. However, most of real edge locations are lost in this process, which causes low measurement accuracy. For accurate measurement, we propose an algorithm which estimates the real boundary between two adjacent pixels in digital imagery, with subpixel accuracy. We first define 1D edge operator based on the moment invariant. To extend it to 2D data, the edge orientation of each pixel is estimated by the LSE(Least Squares Error)line/circle fitting of a set of pixels around edge boundary. Then, using the pixels along the line perpendicular to the estimated edge orientation the real boundary is calculated with subpixel accuracy. Experimental results using real images show that the proposed method is robust in local noise, while maintaining low measurement error.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.544-550
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• 1997

In this study, the advanced on-sided stress wave velocity measurement method was applied to investigate the effects of composition, age and moisture content in concrete. Two concrete specimens that have different composition were used to figure out the change of the Longitudinal and Surface wave velocity due to different composition. The other concrete specimen was cast and the Longitudinal and Surface wave velocity was monitored during curing process. After 28-day old, the effect of moisture content in the concrete specimen to the stress wave velocity is presented in this paper during the time period 43-74 days after casting. For drying process. an aggregate drying oven was used. A conventional ultrasonic through transmission method was used to compare with the results determined by the one-sided method.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.18 no.1
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• pp.83-89
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• 2009

In most multi-stage forging processes, the die spotting process or alignment of punch and die depends on the manual operation. It results a very tedious and inefficient procedure, thus the proper measurement system is needed to improve productivity and accuracy. This paper proposes a measurement system for alignment of die and punch which has a cylindrical holder, and describes the system concepts using 3 eddy-current displacement transducers and precise measurement jig. In order to apply this measurement system to real situations, the measuring procedures and system calibration method, etc. are proposed. Finally, the accuracy and productivity of this measurement system are investigated in this paper.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.12
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• pp.136-144
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• 2021

The purpose of this study was to develop and verify a precision transmission error measurement system for a gear pair. The transmission error measurement system of the gear pair was developed as a measurement unit, signal processing unit, and signal analysis unit. The angular displacement for calculating the transmission error of the gear pair was measured using an encoder. The signal amplification, interpolation, and transmission error calculation of the measured angular displacement were conducted using a field-programmable gate array (FPGA) and a real-time processor. A high-pass filter (HPF) was applied to the calculated transmission error from the real-time processor. The transmission error measurement test was conducted using a gearbox, including the master gear pair. The same test was repeated three times in the clockwise and counterclockwise directions, respectively, according to the load conditions (0 - 200 N·m). The results of the gear transmission error tests showed similar tendencies, thereby confirming the stability of the system. The measured transmission error was verified by comparing it with the transmission error analyzed using commercial software. The verification showed a slight difference in the transmission error between the methods. In a future study, the measurement and analysis method of the developed precision transmission error measurement system in this study may possibly be used for gear design.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.1
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• pp.78-90
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• 2023

Objectives: The purpose of this study is to standardize the process code of the work environment measurement database (WEMD) for the construction of a job-exposure matrix (JEM). Methods: The standard process code (SPC) was reclassified based on process similarity and drawing upon the code used in the existing K2B. It was supplemented through review by industrial hygiene experts. In addition, an index word database related to SPC was created and used for SPC search. A pilot evaluation project was conducted by experts to evaluate the validity of the newly reclassified standard process code. Results: A total of 70 final SPCs were developed, including 31 processes related to the construction industry. Using the Shiny program, we developed a standard code finder that can be used on the web (https://kscf.shinyapps.io/scf_app/). As a result of the pilot evaluation, it was determined that it was easier to search for standard codes than previous codes, so it was highly utilized. Conclusions: It is expected that JEM construction using industry-process information drawing on WEMD data will be possible using the 70 newly standardized process codes.

• Journal of Internet Computing and Services
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• v.8 no.5
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• pp.151-160
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• 2007

A datawarehouse which extracts and saves the massive analysis data is used for marketing and decision support of business. However, the datawarehouse has the problem of increasing the process time and cost as well as has a high risk of process errors because it integrates vast amount of data from distributed environments. Thus, we propose a metrics for measurement in the area of productivity, process quality and data quality. Also through the evaluation using the proposed metrics, we show that our proposal provides productivity enhancement and process improvement.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.5
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• pp.1347-1354
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• 1994

This paper deals with the experimental research, including measurement and analysis and field survey, on the causes of occurring noise defective gear boxes in hoist production plant in order to reduce the fraction of their occurrence. In this reserch following investigations are performed : measurement and gear-boxes, examination of each machining process of production, measurement and analysis of dimensional accuracy of each part, comparative vibration test with exchanging inaccurate parts. From these investigations, it is found that the machining accuracy of pinion gear tooth thickness is the most sensitive factor of noise problem. By maintaining the tooth thickness error within 0.05 mm tolerance in the gear cutting process, the fraction of noise defective gear-boxes are greatly reduced to less than 2%, where the usual rate of it has been 20-50%.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.1
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• pp.16-22
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• 2014

Resonance refers to the magnification of a structural response which occurs when a linear lightly damped system is driven with a sinusoidal input at its natural frequency. An exploratory vibration test (a natural frequency measurement test) is very important for the vibration testing of machine parts, as the value measured in an actual laboratory affects test results. For this reason, it is necessary to estimate the measurement uncertainty to verify the reliability of this type of test. In this study, measurement uncertainty is estimated based on three uncertainty factors. The uncertain factors are the measured points in the machine parts, the resolution of the vibration equipment, and uncertainty of the calibration certificate.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.05a
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• pp.214-218
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• 2002

So far, many kinds of researches on the ceramic chip components and MCM-C RF module especially on the 3-dimensional ceramic module using embedded passives have been performed. LTCC system has many kinds of advantages, like low lass, low cost of process, stability of process etc.. But it's so hard to adjust the characteristics of passives in ceramic module after fabrication. So the exact prediction of behavior of components in high frequency region upper than 2 GHz must be made. In this procedure, the exact measurement is need. In this study, many kinds of measurement Jigs are compared and optimized, and measurement methods of each parameter are designed.

• Journal of the Korean Society for Precision Engineering
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• v.4 no.3
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• pp.60-68
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• 1987

An optoelectronical method for in process monitoring of flank wear of cutting tools is presented. The method is based upon real-time vision technology in which the tool is illuminated by a beam of laser and then the image of wear zone is taken by a vidicon camera. The image is converted to a series of digital pixel data and processed through an algorithm specially developed for measurement of the wear land width. Detailed aspects of the prototype measurement system byilt for experiment are described, and test results are discussed. As conclusions, it is proved that the methods are effec- tive especially for-in situ application with a measuring accuracy of 0.01mm.