• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.43-48
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• 2008

Purpose: This study is to evaluate reliability of geometrical optics properties of spectacle lenses by using ISO and the medical instrument standard of KFDA, which are being sold in Korea. Methods: We used samples of three hundred and ninety eight spectacle lenses of eight company in total. Refractive indices of each samples which were used in experiment were classified into three groups of medium index (1.55~1.56), high index (1.60~1.61) and extra high index (1.67). Results: Conformity of refractive power was 81.61% in total spectacle lenses. The results showed that thickness conformity 90%, appearance conformity 85.18%, size conformity 96.23% and optical center point conformity 99.50% in total. Conclusions: We found that they deviated from the permitting value in many spectacle lenses on refractive power. The results of errors on prism power, surface inspection and optical center point showed small values in total products. In experiment of lens size and thickness, the bulk of indication rates and conformities of samples deviated from the permitting errors.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.2
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• pp.92-97
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• 2006

Hull forms of a high speed small boat have been developed through numerical studies. A round bilge type hull form has been drived form a using chine hull form with HCAD, a hull form variation software. Wave resistance and the flow fields around the ships have been computed using well-known software, WAVIS. This software employs Rankine source method with non-linear tree surface condition as well as dry transom boundary conditions. The round bilge hull form showed better resistance performance than to the chine hull form for the whole speed range. However, considering the building and labor costs of the small shipyard, the chine hull form has been selected and its wave resistance characteristics has been improved by modifying the bow regions and applying the stem wedge. It is found that the effect of stem wedge is quite satisfactory to improve the resistance characteristics of high speed chine hull form.

• Geophysics and Geophysical Exploration
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• v.16 no.4
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• pp.275-283
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• 2013

The sea dike is the most important facility of reclamation projects, and plays an important role in securing freshwater in the reservoir. Systematic research on practical approaches and data analysis techniques are lacking even though some geophysical methods such as electrical resistivity and self-potential surveys are included within the inspection processes. Hence, geophysical methods were considered for improvement of precision safety diagnosis methods after problems in the maintenance system have been identified, such as safety checks and precision safety diagnoses. In addition, geophysical methods customized according to variations in ambient environmental limiting factors such as pore pressure changes by tidal fluctuation, compaction characteristics of the fill materials, and the surface condition of the embankment were suggested.

• Journal of Environmental Science International
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• v.25 no.6
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• pp.767-787
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• 2016

In this study, we analyzed on-site monitoring data for 15 tributaries in Geumho watersheds for 3 years (2011-2013) in order to sort out priorities on water quality characteristics and improvement. As a result of estimating contribution to contamination of the tributary rivers, Dalseocheon showed the highest load densities, despite the smallest watershed area, with 22.7% $BOD_5$, 30.7% $COD_{Mn}$, 31.3% TOC and 47.6% TP. After conducting PCA (principal component analysis) and FA (factor analysis) to analyze water quality characteristics of the tributary rivers, the first factor was classified as $COD_{Mn}$, TOC, EC, TP and $BOD_5$, the second factor as pH, Chl-a and DO, the third factor as water temperature and TN, and the fourth factor as SS and surface flow. In addition, arithmetical sum of each factor's scores based on grading criteria revealed that Dalseocheon and Namcheon were classified into Group A for their highest scores - 96 and 93, respectively -, and selected as rivers that require water environmental management measures the most. Also, water environmental contamination inspection showed that Palgeocheon had the most number of aquatic factors to be controlled: $BOD_5$, $COD_{Mn}$, SS, TOC, T-P, Chl-a, etc.

• Journal of the Korean earth science society
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• v.41 no.3
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• pp.211-221
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• 2020

This study classified outer-ring galaxies using 25,308 galaxies within z=0.05 from the SDSS DR7, which are larger than R_pet>6 arcsec and whose minor-to-major axis ratio (b/a)<0.6. We selected 531 galaxies that have ring-like structures by visual inspection of the color images of 25,308 galaxies; these galaxies with ring-like structures served as a primary sample from which we selected 90 outer-ring galaxies. The final sample of 69 outer-ring galaxies was selected by examining the photometric properties of the candidate galaxies. Their properties were determined by conducting surface photometry on their u, g, r, i, and z images. The frequency of the outer-ring galaxies was found to be 0.3% of the local galaxies. We examined the environment of the outer-ring galaxies using two measures of environment, namely, the projected distance to the nearest-neighbor galaxy and the local background density. We did not observe any notable difference between outer-ring and other galactic environments.

• The Journal of Advanced Prosthodontics
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• v.10 no.4
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• pp.265-270
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• 2018

PURPOSE. The purpose of this in vitro study was to evaluate the accuracy of a new implant impression technique using bite impression coping and a dual arch tray. MATERIALS AND METHODS. Two implant fixtures were placed on maxillary left second premolar and first molar area in dentoform model. The model with two fixtures was used as the reference. The impression was divided into 2 groups, n=10 each. In group 1, heavy/light body silicone impression was made with pick up impression copings and open tray. In group 2, putty/light body silicone impression was made with bite impression copings and dual arch tray. The reference model and the master casts with implant scan bodies were scanned by a laboratory scanner. Surface tessellation language (STL) datasets from test groups was superimposed with STL dataset of reference model using inspection software. The three-dimensional deviation between the reference model and impression models was calculated and illustrated as a color-map. Data was analyzed by independent samples T-test of variance at ${\alpha}=.05$. RESULTS. The mean 3D implant deviations of pick up impression group (group 1) and dual arch impression group (group 2) were 0.029 mm and 0.034 mm, respectively. The difference in 3D deviations between groups 1 and 2 was not statistically significant (P=.075). CONCLUSION. Within limitations of this study, the accuracy of implant impression using a bite impression coping and dual arch tray is comparable to that of conventional pick-up impression.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.6
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• pp.529-536
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• 2015

A defect could be generated in bolts for a use of oil filters for the manufacturing process and then may affect to the safety and quality in bolts. Also, fine defects may be imbedded in oil filter system. So it is very important that such defects be investigated and screened during the multiple manufacturing processes. Therefore, in order effectively to evaluate the fine defects, the FEM simulations were performed to make characterization in the crack detection of the bolts and the parameters such as number of turns of the coil, the coil size, applied frequency were calculated based on the simulation results. Simulations were carried out for the defect signal of eddy current probe. Exciter and receiver were utilized. In this paper, the FEM simulations were performed in both bobbin-type and pancake-type probe, both probes were optimized under Eddy current FEM simulations and the results of calculation were discussed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.935-941
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• 2010

HANARO is an open-tank-in-pool-type Korean research reactor that generates 30MW of thermal power. It differs from power plant reactor in that the heat generated by HANARO is exhausted into the atmosphere through a secondary cooling tower, thus maintaining the core temperature constant. During every monthly inspection of the cooling tower, large vibrations that exceeded the permissible limit were observed at cooling fan gear reducer No. 4 of the cooling tower. The purpose of this study is to identify the origin of the large vibration and to repair it. FFT spectrum analysis is performed to identify the part that caused the large vibration. The results of the frequency analysis showed that the vibration frequency was 354 Hz, which is twice the natural frequency of the pinion gear. A check of the pinion gear revealed that there was a crack on the surface of the pinion gear. After the gear was replaced, the reducer operated normally.

• Journal of the Korean Society for Nondestructive Testing
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• v.19 no.5
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• pp.369-377
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• 1999

Recently, it is gradually raised necessity that thickness of thin film is measured accuracy and managed in industrial circles and medical world. Ultrasonic signal processing method is likely to become a very powerful method for NDE method of detection of microdefects and thickness measurement of thin film below the limit of ultrasonic distance resolution in the opaque materials, provides useful information that cannot be obtained by a conventional measuring system. In the present research. considering a thin film below the limit of ultrasonic distance resolution sandwiched between three substances as acoustical analysis model, demonstrated the usefulness of ultrasonic signal processing technique using information of ultrasonic frequency for NDE of measurements of thin film thickness. Accordingly, for the detection of delamination between the junction condition of boundary microdefect of thin film sandwiched between three substances the results from digital image processing.

• Journal of the Korean Dietetic Association
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• v.26 no.4
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• pp.243-253
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• 2020

The purpose of this study was to set new guidelines for adenosine triphosphate (ATP) bioluminescence hygiene monitoring of distribution trays at children's foodservices. Five dietitians visited 223 foodservices (95 institutional, 128 small) to examine whether they adhered to the norms of 'Keeping distribution tray sanitary by washing/sanitizing' and 'Performing food distribution in a clean and appropriate way'. In this visit, dietitians swabbed 100 ㎠ area of the distribution trays twice, once for obtaining ATP measurements and the second time for Aerobic Plate Counts (APC) using 3M Petrifilm Plates. Chi-square test and ANOVA were applied using SPSS 23.0 software. SPSS 23.0 was used to conduct graphical and statistical analysis of the raw data of ATP measurements, which were further transformed by a Box-Cox transformation. The mean of APC from all the subjects inspected was 3.8×10²±2,102.0 CFU/100 ㎠. A total of 208 (93.3%) trays were observed within the acceptable limits of APC (Pass<5.0×10² CFU/100 ㎠). APCs taken at institutional foodservices showed significantly lower levels (1.4×10²±600.0 CFU/100 ㎠, P<0.01) compared to the small foodservices (5.5×10²±2,718.7 CFU/100 ㎠). No significant differences were observed between the two groups in ATP measurements and in the performance rate of 2 checklist items. As against the 93.3% APC adequacy from the total subjected inspection, total ATP adequacy (Pass≤300 RLU/100 ㎠) was only 71.7%. Therefore, more practical guidelines should be prepared for the assessment of the hygiene of distribution trays. In the graphical and statistical analysis, levels below 250 RLU/100 ㎠ was considered 'Pass', while equal to or greater than 350 RLU/100 ㎠ was considered 'Fail' for distribution trays.