• Journal of Electrical Engineering and Technology
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• v.11 no.4
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• pp.1035-1041
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• 2016

Internal cracks in products are invisible and can lead to fatal crashes or damage. Since X-rays can penetrate materials and be attenuated according to the material’s thickness and density, they have rapidly become the accepted technology for non-destructive inspection of internal cracks. This paper presents a robust crack filter based on local gray level variation and multiscale analysis for automatic detection of cracks in X-ray images. The proposed filter takes advantage of the image gray level and its local variations to detect cracks in the X-ray image. To overcome the problems of image noise and the non-uniform intensity of the X-ray image, a new method of estimating the local gray level variation is proposed in this paper. In order to detect various sizes of crack, this paper proposes using different neighboring distances to construct an image pyramid for multiscale analysis. By use of local gray level variation and multiscale analysis, the proposed crack filter is able to detect cracks of various sizes in X-ray images while contending with the problems of noise and non-uniform intensity. Experimental results show that the proposed crack filter outperforms the Gaussian model based crack filter and the LBP model based method in terms of detection accuracy, false detection ratio and processing speed.

• JSTS:Journal of Semiconductor Technology and Science
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• v.10 no.4
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• pp.292-299
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• 2010

With scaled technology, timing analysis of circuits becomes more and more difficult. In this paper, we review recently developed circuit simulation techniques created to deal with the cost issues of transistor-level simulations. Various techniques for fast SPICE simulations and Monte Carlo simulations are introduced. Moreover, process and aging variation issues are mentioned, along with promising methodologies.

• International Journal of Quality Innovation
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• v.4 no.1
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• pp.148-159
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• 2003

Variation is the archenemy of quality. To reduce or control the variation in a complex production unit, firstly we need to identify the location of the root cause of the variation. This paper discusses the detection of variability and the techniques used for reduction of variation for a production unit consisting of many processes. In the first part of this paper, the background of variability detection in production systems is introduced which is then followed by a weighted network corresponding to correlation matrix of all processes. Based on the network and clustering criterion of maximum spanning tree, a classification of all processes is derived. Furthermore, the variation of each process in a class is determined by residual analysis. In the last part, the use of methods of robust design for the processes with a larger variability is discussed.

• Korean Institute of Interior Design Journal
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• v.14 no.1
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• pp.64-72
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• 2005

The purpose of this study was to analyze the flexible system in a typological way that develops and promotes the various methods of flexible system. The main method of this study was literature review and content analysis on various flexible systems and a case study of flexible housing. The flexible system in this typological analysis was classified into two categories: 'Elements of Flexibility' and 'Variation'. The category of Flexibility Elements was categorized into 'Primary Elements'(e.g., walls, floors, and ceilings),'Secondary Elements'(e.g., doors, windows, and furniture), and 'Tertiary Elements'(e.g., lighting, hues and finishing materials). Variation Effect was classified into 'Visual Variation', 'AppBicative Variation', and 'Layout Variation'. Also, Variation could be classified into 'Finish-centered', 'Application-centered', and 'Layout-centered' The flexible system developed in this study is a basis for further concrete flexible methods.

• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.228-234
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• 2011

The goal of water quality management on stream and watershed is to focus not on discharged loads management but on a water quality management. Discharged loads management is not goal of water quality management but way for perform with total maximum daily loads management. It is necessary to estimate the relation between non-point source with stromwater runoff (NPSSR) and water quality to select a watershed where it is required to manage NPSSR for water quality improvement. To evaluate the effects of NPSSR on stream's water quality, we compare the aspects of water quality in dry and wet seasons using flow duration curve analysis based on flow rate variation data by actual surveying. In this study we attempt to quantify the variation characteristic of water quality and estimate the Inflow characteristic of pollution source with water quality and flow rate monitoring on 10 watersheds. We try to estimate water quality and flow rate by regression analysis and try again regression analysis with each high and low water quality data more than estimations. An analysis of relation between water quality and flow rate of 10 watersheds shows that the water quality of the Nonsan and the Ganggyeong streams had been polluted by NPSSR pollutants. Other eight streams were important point source more than NPSSR. It is wide variation range of $BOD_5$ also high average concentration of $BOD_5$. We have to quantify water quality variation by cv1 in wet season and cv365 in dry season with comparing the estimate of high water quality and low water quality. This method can be used to indicator for water quality variation according to flow rate.

• Radiation Oncology Journal
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• v.12 no.3
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• pp.387-392
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• 1994

Purpose : This study was done to confirm the reference point variation according to variation in applicator configuration in each fractioation of HDR ICR. Materials and Methods : We analyzed the treatment planning of HDRICR for 33 uterine cervical cancer patients treated in department of therapeutic radiology from January 1992 to February 1992. Analysis was done with respect to three view points-Interfractionation A point variation, interfractionation bladder and rectum dose ratio variation, interfractionation treatment volume variation. Interfractionation A point variation was defined as difference between maximum and minimum distance from fixed rectal point to A point in each patient. Interfractionation bladder and rectum dose ratio variation was defined as difference between maximum and minimum dose ratio of bladder or rectum to A point dose in each patient, Interfractionation treatment volume variation was defined as difference between miximum and minimum treatment volume which absorbed over the described dose-that is, 350 cGy or 400 cGy-in each patient. Results The mean of distance from rectum to A point was 4.44cm, and the mean of interfractionation distance variation was 1.14 cm in right side,1.09 cm in left side. The mean of bladder and rectum dose ratio was $63.8\%$ and $63.1\%$ and the mean of interfractionation variation was $14.9\%$ and $15.8\%$ respectively. With fixed planning administration of same planning to all fractionations as in first fractionation planning-mean of bladder and rectum dose ratio was $64.9\%$ and $72.3\%$.and the mean of interfraction variation was $28.1\%$ and $48.1\%$ reapectively. The mean of treatment volume was $84.15cm^3$ and the interfractionation variation was $21.47cm^2$. Conclusion : From these data, it was confirmed that there should be adapted planning for every fractionation ,and that confirmation device installed in ICR room would reduce the interfractionation variation due to more stable applicator configuration.

• Journal of Korean Society for Quality Management
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• v.22 no.4
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• pp.79-101
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• 1994

In modern manufacturing, a product consists of many components created by different processes. Variations in the individual component dimensions and in the processes may result in unacceptable final assemblies. Thus, engineers have increased pressure to properly set tolerance specifications for individual components and to control manufacturing processes. When a proper variation stack-up analysis is not performed for all of the components in a functional system, all component parts can be within specifications, but the final assembly may not be functional. Thus, in order to improve the performance of the final assembly, a proper variation stack-up analysis is essential for specifying dimensional tolerances and process control. This research provides a detailed case example of the use of variation stack-up analysis using a Monte Carlo simulation method to improve the defect rate of a complex process, which is the commutator brush track undercut process of an armature assembly of a small motor. Variations in individual component dimensions and process mean shifts cause high defect rate, Since some dimensional characteristics have non-normal distributions and the stack-up function is non-linear, the Monte Carlo simulation method is used.

• Journal of Mechanical Science and Technology
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• v.14 no.10
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• pp.1151-1158
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• 2000

Combustion analysis based on cylinder-pressure provides a mechanism through which a combustion researcher can understand the combustion process. The objective of this paper was to identify the most significant sources of cycle-to-cycle combustion variability in a spark ignition engine at idle. To analyse the cyclic variation in a test engine, the burn parameters are determined on a cycle-to-cycle basis through the analysis of the engine pressure data. The burn rate analysis program was used here and the burn parameters were used to determine the variations in the input parameter-i. e., fuel, air, and residual mass. In this study, we investigated the relationship of indicated mean effective pressure (IMEP), coefficient of variation (COV) of IMEP, burn angles, and lowest normalized value (LNV) in a spark ignition engine in a view of cyclic variations.

• Journal of the Korean Institute of Educational Facilities
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• v.8 no.4
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• pp.17-32
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• 2001

A main contents of this is to abtain the result of investigation and analysis of facilities & using space of Variation Type's middle school in Japan. we choose the sample of Japan Middle school managing variation type. Because the Japan's exiting educational system is very similar with Korea's existing educational system. We have planning about investigation and analysis of facilitie's present condition & using space of middle school in Japan. And we have also planning to have a hearing and interview investigation to teachers and students. A aim of this study is to abtain a guide of variation type space-planning in Middle school. For the aim, it is necessary to understand Japan's Middle school facilities condition and compare with Korea and Japan. A main content of study is as follow. o A collection of data and thesis of Japan's variation type middle school. o A check of curriculum of Japan's middle school. o A current of Japan's variation type middle mchool. history of construction circumstances, using situation of variation type, merit and demerit.

• Plant Resources
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• v.8 no.3
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• pp.293-299
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• 2005

This study used RAPD markers to assume genetic diversity and variation in selected populations of Hovenia dulcis var. koreana. Ratio of polymorphic RAPD markers were 93.4% in selected populations of Hovenia dulcis Thunb., difference of genetic structure among populations and within populations showed 16.45%, 83.55%, respectively in amount of total genetic variation of 4 populations. Total gene diversity($H_T$) that show genetic diversity appeared 0.313 and coefficient of gene differentiation($G_{ST}$) that compare genetic differentiation of populations appeared 0.1645, analysis of AMOVA for variation among populations and within populations was significantly different (P<0.001). Genetic diversity of whole populations showed that 12.44% difference among population and 87.56% difference within populations. As a result, difference within populations was larger than difference among populations in genetic diversity. Nei's genetic distance and cluster analysis appeared that mean genetic distance among populations was 0.076, thus dividing two main groups and geographic relationship did not show in populations.