• Structural Monitoring and Maintenance
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• v.9 no.3
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• pp.221-235
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• 2022

Among nondestructive damage detection methods, impedance-based methods have been recognized as an effective technique for damage identification in many kinds of structures. This paper proposes a method to detect cracks in metal structures by combining electro-mechanical impedance (EMI) responses and artificial neural networks (ANN). Firstly, the theories of EMI responses and impedance-based damage detection methods are described. Secondly, the reliability of numerical simulations for impedance responses is demonstrated by comparing to pre-published results for an aluminum beam. Thirdly, the proposed method is used to detect cracks in the beam. The RMSD (root mean square deviation) index is used to alarm the occurrence of the cracks, and the multi-layer perceptron (MLP) ANN is employed to identify the location and size of the cracks. The selection of the effective frequency range is also investigated. The analysis results reveal that the proposed method accurately detects the cracks' occurrence, location, and size in metal structures.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.7
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• pp.3169-3175
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• 2011

This paper describes the design of size-reduced directional coupler using the artificial dielectric substrate and its increased effective permittivity. Directional couplers are widely used in measuring RF power indirectly and coupling signal power. Artificial dielectric substrates have higher effective dielectric constant than standard dielectric substrate due to the lots of metalized via-holes, and the increased effective permittivity results in size-reduction of circuits. As a design example, 15dB directional couplers are designed on the standard substrate and artificial dielectric substrate and their size are compared. The size of the directional coupler using the artificial dielectric substrate is only 1/3 of that designed using the standard substrate, while the performances are preserved. In addition, the measured performances of the size-reduced coupler are well agreed with the simulated ones. The measured coupling coefficient, matching, and insertion loss at 2GHz are -14.62dB, -24.1dB, and -0.38dB, respectively.

• Journal of the Korean Home Economics Association
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• v.46 no.9
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• pp.99-112
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• 2008

The increasing rate of obesity in school aged children has become a conspicuous social phenomenon in Korea. This has been linked to greater economic growth, increasingly westernized dietary habits, and a consumer driven society. Given that obesity can lead to social exclusion or unfavorable attention by other students in a school setting, the design of plus-size garments have become important for effective appearance management skills. This research aimed to establish a somatotype database for obese school boys, aged 10 to 12, in order to develop a sizing system for plus-size upper garments. In order to measure somatotype of average and obese school boys, five categories were recorded; height, obesity, length of trunk, thickness of neck and chest. For obese boys, subcutaneous fat thickness and position of B.P/shoulder point factors were recorded. Obesity factor was subdivided into overall and specific ones, and while the deviation of obese body types was severe compared to the average type. Obese body type showed significantly higher measurements in width, girth, thickness. This is linked to the fact that the frequency ratio of obesity increases with age. Stature and chest were chosen as control dimensions for boys' wear. As crosstabulation of stature(5cm interval) and chest girth(2, 3 and 4cm), and stature(5cm interval)/chest girth(3cm interval) sizing system showed, the most effective cover ratio and adaptability to the data distribution $25{\sim}75$ quartile. Based on the findings, 10 sizes were formulated for average body type, while 18 sizes were formulated for obese type, whose size cover ratios were 48% and 62.9%, respectively. The primary ranges of stature were $145cm{\sim}150cm$, while those of chest girth were $79{\sim}82cm$. Each size was declared as "chest-somatotype{A(average)/O(obesity)-stature". This study proposed a plus-size upper garment sizing systems for obese boys, accompanied with reference measurements for suit, casual wear and underwear. The finding showed that the two systems were totally separate and not overlapping, meaning that plus-size sizing system is essential for obese school boys. The obesity type system had more size and wider range specs.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.2
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• pp.201-210
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• 2015

Purpose: In order to aggregate effect of the improvement of binocular vision function by vision therapy, total mean effect size, mean effect size by dependent variables, and effect size by characteristics of the subjects and characteristics of treatment were analyzed by meta-analysis. Methods: We analyzed data from 14 Korean National primary studies, which reported effects of vision therapy programs, using meta-analysis. Results: The effect size of total mean was 1.207, which showed high effect. The mean effect size according to the subcategory of the binocular dysfunctions was the highest for vergence dysfunctions group (2.989), followed by accommodative dysfunctions group (0.868) and group with both vergence dysfunctions and accommodative dysfunctions (0.692). The effect size according to the characteristics of the subjects was the highest in the vision therapy conducted in the binocular dysfunctions group (2.509) that had no other dysfunctions. The mean effect size according to the number of programs was the highest (2.310) for 7 times a week. Vision therapy for improving the binocular functions was the most effective (2.019) in 8 weeks later from vision therapy start. Conclusions: It can prove that the therapy for the improvement of binocular vision function is effective through that each result of the vision therapy effect is converted to mean effect size, and being objectifying the mean effect size.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.4
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• pp.480-486
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• 2005

The main goals of this work are to investigate the effect of molecular weight distribution(MWD) and activated carbon adsorption capacity after conventional coagulation and enhanced coagulation. The ozonation was very effective to decompose the NOM to smaller size and to remove molecular smaller than 1,000. The concentration of DOC was reduced 0.25mg/L and 0.56mg/L by the conventional coagulation and the enhanced coagulation, respectively The conventional coagulation was not effective to remove NOM. However, the enhanced coagulation was effective to remove MW bigger than 10,000. The higher MW was shifted to smaller weight by ozonation in the raw water and the after conventional coagulation. After enhanced coagulation the MW had not changed significantly by ozonation. Also, it was observed that the ozone dosage did not have significant impact on MW shifting to smaller size. The adsorption capacity simulated by IAST comparing K values showed that the adsorption capacity was not impacted by ozone doses. There was very strong correlation between MW smaller than 10,000 and the mid- and strongly adsorbable fractions.

• Wind and Structures
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• v.6 no.2
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• pp.127-140
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• 2003

An investigation into the effect of corner cuts on the Strouhal number of rectangular cylinders with various dimensional ratios and various angles of attack is described. The Strouhal number given as a function of corner cut size is obtained directly from the aerodynamic behavior of the body in a uniform flow through a series of wind-induced vibration tests. For a quick verification of the validity of the Strouhal numbers obtained in this way, they are compared with the approximated the Strouhal numbers based on Shiraishi's early research. The test results show that the Strouhal number of the model with various corner cuts has a fluctuating trend as the angle of attack changes. For each cutting ratio as the angle of attack increases at each cutting ratio above $15^{\circ}$, the Strouhal number decreases gradually, and these trends are more evident for larger corner cut sizes. However, a certain corner cut size which is effective in reducing the wind-induced vibration can be identified by larger Strouhal numbers than those of other corner cut sizes. Three distinct characteristics of Strouhal number variation can be identified in three regions which are termed as Region I, II, and III based on the general trend of the test results. It is also found that the corner cut is effective in one region (Region-II) and less effective in another one (Region-III) when only the vortex-induced vibration occurs.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.4
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• pp.144-150
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• 2005

Gas-assisted injection molding (GAIM) process is reducing the injection pressure during mold filling required as well as the shrinkage and warpage of the part and cycle time. Despite of these advantages, this process introduces new parameters and makes the application more difficult because the process interacts between gas and melt during injection molding process. Important GAIM factors that involved in this process include gas penetration design, locations of gas injection points, shot size, gas injection delay time as well as common injection molding parameters, gas pressure and gas injection time. In this study, the experiments were conducted to investigate effects of GAIM process variables on the gas penetration for PP and ABS moldings by changing gas injection point. Taguchi method was used fer the design of experiment. When the gas was injected at cavity's center, the most effective factor was shot size. When the gas was injected at cavity's end, the most effective factor was melt temperature. Injection speed was also an effective factor in GAIM process.

• Korean Journal of Community Nutrition
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• v.9 no.1
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• pp.81-89
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• 2004

A systematic review and meta-analysis of the literatures was conducted to evaluate the effectiveness of nutrition intervention by dietitian. The 31 studies that were all randomized controlled trials, were identified from computerized search of published researches on MEDLINE, Embase database until January, 2003 and review of reference lists. The main search terms were the combination “dietitian”, “dietary intervention”, “nutrition intervention” or “nutritional intervention” and “effectiveness”. The subgroup analysis was performed by the publication year, quality score, type of disease, content of intervention, intervention provider, type of intervention (nutritional counseling and education/nutrilion counseling and education + diet modification), method of intervention (individual/group/individual + group) and follow-up period. Two reviewers independently selected trials for inclusion, assessed the quality and extracted the data. The meta-analysis of 31 studies based on the random effect model showed that the medical nutrition therapy was significantly effective in treating the diseases (effect size 0.1715 : 95% confidence interval 0.0938-0.2491). This study showed the clear evidence of the effectiveness of nutrition intervention through the meta-analysis. So the nutrition intervention by dietitian should be recommended and recognized as the effective therapy of treating the diseases. Also the nutrition intervention should be conducted regularly to maintain the effectiveness of the nutrition intervention. The nutrition intervention was significantly effective in treating the diseases on the random effect model (effect size 0.1715 : 95% confidence interval 0.0938-0.2491).

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.4
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• pp.3991-4000
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• 1975

It is the aim of this study to investigate the influence of the factors in the sprayer nozzle for the travelling distance and to get nozzle design data in relation to the nozz1e with and without swirl plate. The factors of sprayer nozzle are composed of the spraying pressure, the helical angle of swirl plate, the helical groove depth of swirl plate, the distance of vortex chamber the slope of nozz1e cap, the curvature of nozzle cap and the hole diameter of nozz1e cap. The travelling distance and the size of sprayed particle are experimeted indoors by the factorial arrange-ment according to the 5 each level of the above factors. The results of this stupy are summarized as follows; 1. In the nozzle with swirl p1ate there were remarkable significance among factors each other, while without swirl plate were no significance. 2. The helical angle and groove depth in the nozzle with swirl plate were the highest effective factors. The effect of helical angle was very remarked in the quadratic curve with minium value. 3. The correlation betweenthe travelling distance and the sprayed particle size was no high and under 250 micron in the case with swirl plate, and there was higher correlation in the case without swirl plate. 4. The new ideal development of the swirl plate using of the most effective helical angle and groove depth will probably show the possiblities to make effective travelling distance over 8 meters and more over and to make average particle diameter under 300 micron.

• International Journal of Precision Engineering and Manufacturing
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• v.7 no.2
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• pp.8-11
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• 2006

Gas-assisted injection molding (GAIM) process reduces the required injection pressure during mold filling stage as well as the shrinkage and warpage of the part and cycle time. Despite of these advantages, this process needs new parameters and makes the application more difficult because gas and melt interact during the injection molding process. Important GAIM factors involved in this process are gas penetration design, locations of gas injection points, shot size, delay time to inject gas as well as common injection molding parameters. In this study, the experiments are conducted to investigate effects of GAIM process variables on the gas penetration for PP (Polypropylene) and ABS (Acrylonitrile Butadiene Styrene) moldings by changing the gas injection point. Taguchi method is used for the design of the experiments. When the gas is injected at a cavity's center, the most effective factor is the shot size. When the gas is injected at a cavity's end, the most effective factor is the melt temperature. The injection speed is also an effective factor in GAIM process.