• 한국가시화정보학회:학술대회논문집
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• 2001.12a
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• pp.44-52
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• 2001

A micro-PIV(particle image velocimetry) measurement has been conducted to investigate flow fields in such microfluidic devices as microchannels and micronozzle. The present study employs a state-of-art micro-PIV system which consists of epi-fluorescence microscope, 620nm diameter fluorescent seed particles and an 8-bit megapixel CCD camera. Velocity vector fields with a resolution of $6.8\;\times\;6.8{\mu}m$ has been obtained, and the attention has been paid on the effect of varying measurement conditions of particle diameter and particle concentration on the resulting PIV results. In this study, the microfluidic elements were fabricated on plastic chips by means of MEMS processes and a subsequent molding process. Flow fields in a variety of microchannels as well as micronozzle have been investigated.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.11
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• pp.991-997
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• 2013

In this paper, we propose a CFWC (CCD and fuzzy PID based width control) scheme to obtain the desired delivery width margin of a vertical rolling mill in hot strip process. A WMS(width measurement system) is composed of two line scan cameras, an edge detection algorithm, a glitch filter, and so on. A dynamic model of the mill is derived from a gauge meter equation in order to design the fuzzy PID controller. The controller is a self-learning structure to select the PID gains from the error and error rate of the width margin. The effectiveness of the proposed CFWC is verified from simulation results under a width disturbance of the entry in the mill. Using a field test, we show that the performance of the width control is improved by the proposed control scheme.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.11
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• pp.974-978
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• 2013

AVI (Automatic Vision Inspection) systems automatically detect defect features and measure their sizes via camera vision. AVI systems usually report different measurements on the same defect with some variations on position or rotation mainly because different images are provided. This is caused by possible variations from the image acquisition process including optical factors, nonuniform illumination, random noises, and so on. For this reason, conventional area based defect measuring methods have problems of robustness and consistency. In this paper, we propose a new defect size measuring method to overcome this problem, utilizing volume information that is completely ignored in the area based defect measuring method. The results show that our proposed method dramatically improves the robustness and consistency of defect size measurement.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.33-40
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• 2001

In this research, the cracking of tunnel concrete lining was investigated and analyzed through long-term measurement and nonlinear numerical analysis. For one year after the casting of lining, the stresses and strains were measured by the sensors installed in hard rock tunnel lining. The measurements showed that only small stresses which were less than cracking stress occurred in every survey sections regardless of sensor directions. It could be induced that the external load applied to the lining was small or ignorable. Also, it was carried out short-term numerical analysis based on such site condition as ambient temperature, the- degree of overbreak and mold staying period. Long-term numerical analysis based on creep & shrinkage and nonlinear cracking was carried out. The output showed that construction condition and ambient environments could make the lining concrete crack without external loads. The cracks formed in this process does not indicate the structural instability of the tunnel.

• Journal of the Korean Home Economics Association
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• v.39 no.2
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• pp.15-24
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• 2001

The purpose of this research was to investigate the factors affecting the labor supply of married women. Based on the theoretical review of the process for the labor supply of married women and the review of previous research, the emperical specification was deduced as a function of husband's income, assets, education and age, the number of children and home ownership. The data of this research was collected with questionnaire in 1998. The data consisted of the answers by 200 married women. For the measurement of the emperical specification, Logit, Tobit, and Selection Bias Corrected Regression which modifies selection bias were used. Although several different discussions can made depending on the measurement method, the emperical result of this research showed that the labor supply of married women is explained by husband's income, assets, the level of education and work experience.

• Journal of Mechanical Science and Technology
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• v.19 no.10
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• pp.1885-1890
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• 2005

The contour method relies on deformations that occur when a residually stressed component is cut along a plane. The method is based on the elastic superposition principle. When plasticity is involved in the relaxation process, stress error in the resulting measurement of residual stress would be caused. During the cutting the specimen is constrained at a location along the cut so that deformations are restrained as much as possible during cutting. With proper selection of the constraining location the plasticity effect can also be minimized. Typical patterns of longitudinal welding residual stress state were taken to assess the plasticity effect along with constraining locations.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.49-53
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• 2004

Thin spot welding is frequently used for industrial purpose, such as automobile and aerospace industries and household appliances due to its high performance. In these days, the systemization of welding process made it possible to produce more precise or smaller electric parts. And when it comes to welding of steel sheets, the size of nugget must be getting smaller. Therefore, welding conditions are limited to avoid defects, such as deformation, damage and weakening of joining area. In this research, thin spot welding establishes the welding conditions, and then the measurement of the nugget size by the nondestructive inspection has been conducted. As a result, the right estimation of the nugget size, the detection of corona bond near joining area, the selection of the optimum ultrasonic mode, and setup for ultrasonic inspection are studied. From the trustworthy solutions of the nugget size estimated by results of measurement, the optimum inspection conditions depending upon the width of welding parts are determined as well.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1255-1258
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• 2008

Roll to roll (R2R) system, known as 'web processing', is the process of producing these electronic devices on a roll of flexible plastic. With the need of improved performance and productivity in R2R industry, effective control and on-line supervision for web quality is essential. In this report, we present a system for on-line measurement of wrinkles, one of defects incurring due to compressive stresses developed in the web. This system is able to capture an image generated when a well defined line shape laser beam passes through a transparent web. The system calculates 3D shape information, including the height of the wrinkle on the web, and displays the images for the shape information of the web in real time. By using area scan camera and machine vision laser, this system takes more advantages of setting up as a simple and low cost system compared to the line scan camera systems that widely used in web manufacturing. Specific calibration method and analysis on the achievable accuracy will be discussed.

• Korean Management Science Review
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• v.34 no.2
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• pp.67-83
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• 2017

This paper proposes a R&D project performance measurement model for private firms combining balanced scorecard (BSC) and data envelopment analysis (DEA). The efficiency of R&D projects is measured in terms of each of the three perspectives of BSC by using DEA : the internal process perspective (DEA-P), the customer perspective (DEA-C), and the financial perspective (DEA-F). The performance indicators of the three perspectives of BSC are considered as outputs of the corresponding DEA models. To provide strategic implications for R&D planning, we also propose the R&D project performance matrices composed of two different types of efficiency dimensions. The proposed model is expected to be fruitfully utilized for R&D performance measurement of private firms.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.7 s.178
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• pp.1748-1752
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• 2000

In this paper, the measurement technique of cutting temperatures of shear zone using implanted thermocouples is proposed in ball end milling. K-type thermocouple implanted in the hole of workpieces is directly cut in order to measure temperatures of the shear zone in cutting process. Experiments are performed for a nickel based superalloy(Inconel 718) using a ball nose end mill. The results show that the cutting temperature in shear zone is about 3200C at the cutting speed of 90m/min with dry.