• Journal of Welding and Joining
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• 제14권2호
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• pp.65-70
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• 1996

Detonation velocity of domestic expolsives was measured using the Dautriche method. The variables employed in this study were the thickness of explosive and the amount of salt added in the ammonium nitrate(AN) explosive. As the results of this study, it was shown that the detonation velocity increases with an increase of explosive thickness but decreases with an increase of salt content. It was further demonstrated that the detonation velocity decreases rather rapidly when the salt content increases over 20 percent. In addition, the accuracy of Dautriche method was evaluated as a preliminary study and its result showed that this method is quite reliable with an experimental error of less than 10 pct.

• Corrosion Science and Technology
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• 제14권1호
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• pp.33-39
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• 2015

Pipe wall-thinning by flow-accelerated corrosion and various types of erosion is significant damage in secondary system piping of nuclear power plants(NPPs). All NPPs in Korea have management programs to ensure pipe integrity from degradation mechanisms. Ultrasonic test(UT) is widely used for pipe wall thickness measurement. Numerous UT measurements have been performed during scheduled outages. Wall-thinning rates are determined conservatively according to several evaluation methods developed by Electric Power Research Institute(EPRI). The issue of reliability caused by measurement error should be considered in the process of evaluation. The reliability analysis method was developed for single and multiple measurement data in the previous researches. This paper describes the application results of reliability analysis method to real measurement data during scheduled outage and proved its benefits.

• 자원환경지질
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• 제29권5호
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• pp.629-637
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• 1996

In this paper a numerical experiment is conducted to determine the low acoustic impedance of a thin oil or gas reservoir from a seismogram by using the generalized linear inversion method. The seismograms used are normal incident synthetic seismograms containing p-wave primary reflections, multiples, and peg-leg multiples on the layers consisting of oil-, gas-, water-filled sandstone incased in shales. In this experiment the acoustic impedance, the location of reservoir boundary, thickness, and source wavelet are assumed initially and revised iteratively by the least-squares-error technique until the difference between the seismogram and calculated one is very small. This experiment shows that the acoustic impedance and thickness, about 10 m thick, can be determined by the inversion.

• 대한기계학회논문집B
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• 제25권8호
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• pp.1046-1052
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• 2001

This study has been performed experimentally to measure the frost properties over a cold flat plate in order to obtain the correlations of the frost properties with various environmental parameters. Correlations of the frost surface temperature, thickness, density, and thermal conductivity are presented along with the experimental results as a function of environmental parameters, distance from the leading edge of test plate, and time. These correlations can be used to predict the frost properties with a maximum error of 8% in the following ranges : air temperature 15∼25$\^{C}$, relative humidity 60∼80%, air velocity 1∼3m/s and cooling plate temperature -15∼-25$\^{C}$.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.212-212
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• 2000

This study was performed to construct a hot strip speed measuring system and check over whether the measured speed can be used for improving the mass flow of the head-end part of a hot strip in the 7-stand finishing mill. Because the mass flow in hot rolling mill affects the looper operation and the thickness and width control of a strip, accurate measurement of strip speed ie important. The measured speed was compared with the roll speeds of No. 6 and No.7 stand to check the performance of the system and analyzed to find how to apply the speed. As a result, it is shown that the accuracy of the system is enough, strip thickness error can be reduced by -275∼+200$\mu\textrm{m}$ using the measured speed and the existing FSU model has low accuracy for predicting forward slip rate. A neural network was developed to calculate forward slip rate instead of FSU model. The test result of the neural network shows that the neural network is more accurate than the FSU model.

• 한국정밀공학회지
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• 제16권10호
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• pp.101-108
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• 1999

Most of researches for deep drawing process have been performed on the formability of axisymmetric blank, but there is an insufficient study on the formability of non-axisymmetric blank. In addition, the conventional blank shape has been determined by the trial-and-error method using industrial experience and post processing test. Therefore only approximated shape of the blank can be presented. In this study, the optimal blank shape and concrete drafting method in deep drawing process with biaxisymmetric elliptical shape is proposed. Through the deep drawing experiment, it is found that the optimal blank shape gives the most uniform thickness of the products in the first process

• Design & Manufacturing
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• 제2권3호
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• pp.22-27
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• 2008

Forming of PET bottle was performed by injection-stretch blow molding. Blow molding is process of contacting the dies with air of materials by pressing. In this paper, the aim was to improve reliability of technical stabilization for the PET bottle that is last productive product and process technology which was able to do maximization by a preform performance enhancement of the uniform thickness that took temperature and a characteristic of materials. Preform design and dies manufacture were conducted using injection blow molding analysis results. Therefore thickness error of 5% for PET bottle can be obtained in this paper.

• Journal of Biosystems Engineering
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• 제24권1호
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• pp.67-74
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• 1999

A prototype cut-flower sorter was developed and tested for its performance with five varieties of roses. Support plates driven by a chain mechanism transported the roses into an image inspection chamber. Color image processing algorithms were developed to evaluate the length, thickness, and straightness of stem and color, height, and maturity of bud. The average absolute errors of the system for the measurements of stem length, stem thickness, and height of bud were 19.7 mm, 0.5 mm, and 3.8 mm, respectively. The results of classification by the sorter were compared with those of a human inspector for straightness of stem and maturity of bud. The classification error for the straightness of stem was 8.6%, when both direct image and reflected image by a mirror were analyzed. The accuracy in classifying the maturity of bud varied among the varieties, the smallest for‘Nobless’(1.5%) and the largest for‘Rote Rose’(13.5%). The time required to process a rose averaged 2.06 seconds, equivalent to the capacity of 1,600 roses per hour.

• Smart Structures and Systems
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• 제1권3호
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• pp.309-324
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• 2005

This paper presents an efficient and accurate coupled beam model for piezoelectric bimorphs based on improved first-order shear deformation theory (FSDT). The model combines the equivalent single layer approach for the mechanical displacements and a layerwise modeling for the electric potential. General electric field function is proposed to reasonably approximate the through-the-thickness distribution of the applied and induced electric potentials. Layerwise defined shear correction factor (k) accounting for nonlinear shear strain distribution is introduced into both the shear stress resultant and the electric displacement integration. Analytical solutions for free vibrations and forced response under electromechanical loads are obtained for the simply supported piezoelectric bimorphs with series or parallel arrangement, and the numerical results for various length-to-thickness ratios are compared with the exact two-dimensional piezoelasticity solution. Excellent predictions with low error estimates of local and global responses as well as the modal frequencies are observed.

• 산업공학
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• 제9권3호
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• pp.298-305
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• 1996

Cold rolling mill process in steel works uses stands of rolls to flatten a strip to a desired thickness. Most of rolling processes use mathematical models to predict rolling force which is very important to decide the resultant thickness of a coil. In general, these mathematical models are not flexible for variant coil types and cannot handle various elements which is practically important to decide accurate rolling force. A corrective neural network is proposed to improve the accuracy of rolling force prediction. Additional variables-composition of the coil, coiling temperature and working roll parameters-are fed to the network. The model uses an MLP with BP to predict a corrective coefficient. The test results using 1,586 process data collected at POSCO in early 1995 show that the proposed model reduced the prediction error by 30% on average.