• Journal of Conservation Science
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• v.25 no.3
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• pp.233-244
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• 2009

This study was focused on the transducer and suitable contact material for stone cultural heritage, and the correlation of direct-indirect method in rock types for scientific development and quantitative evaluation technique of the ultrasonic measurements. As a result, it was identified the transducer (UTREXTX(RX)54kHz) and contact material (rubber clay) of the type 3 were appropriate for the ultrasonic measurements of stone cultural heritage. The direct-indirect correction factors of type 3 were calculated 1.50 for granite, 1.38 for gabbro, 1.58 for quartz diorite, respectively. This result is the first study for improvement in reliability for the ultrasonic measurements, and it will contribute to establishment of the ultrasonic survey method for stone cultural heritage. Also, complementary studies considering the surface irregularity of rocks and various contact materials will carry out, and the database about correlation of direct-indirect in rock types will establish.

• Journal of the Korean Geosynthetics Society
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• v.19 no.1
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• pp.45-53
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• 2020

There is an increasing tendency to try to make predictive analysis using measurement data based on machine learning techniques in the railway industries. In this paper, it was predicted that Track quality index (TQI) using vehicle acceleration data based on the machine learning method. The XGB (XGBoost) was the most accurate with 85% in the all data sets. Unlike the SVM model with a single algorithm, the RF and XGB model with a ensemble system were considered to be good at the prediction performance. In the case of the Surface TQI, it is shown that the acceleration of the z axis is highly related to the vertical direction and is in good agreement with the previous studies. Therefore, it is appropriate to apply the model with the ensemble algorithm to predict the track quality index using the vehicle vibration acceleration data because the accuracy may vary depending on the applied model in the machine learning methods.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.6
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• pp.59-66
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• 2013

Spray characteristics of single round jet with liquid nitrogen and coaxial spray with liquid nitrogen and gaseous argon were observed. Shadowgraph method was used for spray visualization, and density gradient magnitude image was used to analyse the result. In subcritical condition, irregularity of the jet surface was harder in the coaxial spray. In supercritical condition, diffusion of nitrogen injected from shear coaxial injector was faster than single jet. Jet diameter was induced by averaging images, in supercritical condition, difference of diameter of coaxial jet was rapidly decreased than that of single jet.

• Transactions on Electrical and Electronic Materials
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• v.18 no.4
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• pp.207-210
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• 2017

The suspension arrangement of insulators provides flexibility and assists in power transmission in transmission lines. The performance of the insulator string is strongly influenced by the environmental conditions to which it is exposed, its shape and the inherent material properties of suspension-type insulators. The suspension-type insulators are mostly made from glass, porcelain and ceramic material due to their high resistivity. Irregularity in charge distribution throughout the porcelain insulator may lead to accelerated aging and electrical breakdown. A very high and steep lightning impulse voltage may also cause breakdown of suspension-type insulators. We investigated various material characteristics such as alumina addition, surface morphology, x-ray diffraction pattern and relative density of suspension porcelain insulators manufactured in 1989 (36,000 lbs.), 1995 (36,000 lbs.) and 2001 (36,000 lbs.) by the KRI Company for use in 154 kV high power transmission lines. We compared the material characteristics of these porcelain insulators with that of the top-of-the-line porcelain insulators (36,000 lbs.) manufactured by the NGK Company in 2000. These suspension-type porcelain insulators were exposed to arc and flashover tests to examine their electrical and mechanical strength. It was noted that alumina addition (17 wt.%) for K-2001 was one of the major contributors to the enhancement of the performance of the porcelain insulators and to their ability to withstand very high current generation during the arc test. The porcelain insulators manufactured during 2001 also showed the highest relative density of 95.8% as compared to the other insulators manufactured in 1989 and 1995 respectively 94.2% and 91.5%. We also discuss reports of various failure modes of suspension-type porcelain insulators.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.25 no.6
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• pp.441-452
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• 2022

Congenital diarrheal disorders (CDDs) with genetic etiology are uncommon hereditary intestinal diseases characterized by chronic, life-threatening, intractable watery diarrhea that starts in infancy. CDDs can be mechanistically divided into osmotic and secretory diarrhea. Congenital tufting enteropathy (CTE), also known as intestinal epithelial dysplasia, is a type of secretory CDD. CTE is a rare autosomal recessive enteropathy that presents with intractable neonatal-onset diarrhea, intestinal failure, severe malnutrition, and parenteral nutrition dependence. Villous atrophy of the intestinal epithelium, crypt hyperplasia, and irregularity of surface enterocytes are the specific pathological findings of CTE. The small intestine and occasionally the colonic mucosa include focal epithelial tufts. In 2008, Sivagnanam et al. discovered that mutations in the epithelial cell adhesion molecule (EpCAM, MIM# 185535) were the genetic cause of CTE (MIM# 613217). More than a hundred mutations have been reported to date. Furthermore, mutations in the serine peptidase inhibitor Kunitz type 2 (SPINT2, MIM# 605124) have been linked to syndromic CTE. In this study, we report the case of a 17-month-old male infant with congenital diarrhea. Despite extensive etiological workup, no etiology could be established before admission to our center. The patient died 15 hours after being admitted to our center in a metabolically decompensated state, probably due to a delay in admission and diagnosis. Molecular autopsy with exome sequencing revealed a previously reported homozygous missense variant, c.757G>A, in EpCAM, which was confirmed by histopathological examination.

• Journal of Korean Foot and Ankle Society
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• v.27 no.4
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• pp.137-143
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• 2023

Purpose: Autologous osteochondral transplantation (AOT) is indicated for patients with a large osteochondral lesion of the talus (OLT), accompanying subchondral cyst, and the failure of bone marrow stimulation (BMS) procedures. Despite the many reports on the clinical results of surgical treatment for medial osteochondral lesions, those of lateral lesions are rare. This paper reports the intermediate-term clinical outcomes after AOT for lateral OLTs. Materials and Methods: Twenty-one patients with lateral OLTs were followed up for at least three years after AOT. The clinical evaluations comprised the Foot and Ankle Outcome Score (FAOS) and Foot and Ankle Ability Measure (FAAM). The radiographic assessment included the irregularity of the articular surface (subchondral plate), the progression of degenerative arthritis, and the changes in talar tilt angle and anterior talar translation. Results: The mean FAOS and FAAM scores improved significantly from 42.1 to 89.5 and 39.5 to 90.6 points, respectively, at the final follow-up (p<0.001). The radiological evaluation revealed two cases (9.5%) of articular step-off ≥2 mm and 1 case (4.8%) of progressive arthritis. The mean talar tilt angle and anterior talar translation improved significantly. As postoperative complications, there was one case of a local wound problem, one case of superficial peroneal nerve injury, and one case of donor site morbidity. At a mean follow-up of 62.3 months, no patient showed a recurrence of instability or required reoperation for OLT. Conclusion: AOT for the lateral OLTs demonstrated satisfactory intermediate-term clinical outcomes, including daily and sports activity abilities. Most OLT could be accessed through lateral ligament division and capsulotomy, and the incidence of iatrogenic complications, such as recurrent sprains or chronic instability, was minimal. AOT appears to be an effective and relatively safe treatment for patients with large lateral osteochondral lesions unresponsive to conservative therapy, with subchondral cysts, or with failed primary BMS.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.2
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• pp.121-130
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• 2014

Purpose: To assess the surface profile of dentinal wall, dentin chips and smear layer during the canal shaping with rotary (ProTaper) and ProFile and reciprocating (WaveOne) nickel-titanium file. Materials and Methods: Sixty human extracted mandibular premolars and incisors with single canals were randomly selected. Three experimental groups (n = 20) were instrumented with ProTaper (F2), ProFile (25/.06), WaveOne (25/.08) with irrigation of 2.5% NaOCl. The dentin chips were collected from flute of file during each canal preparation. After canal preparation, roots were grinded and each group was divided into two subgroups (n = 10) for surface profile and smear layer of dentinal wall of shaped root canal. Each specimen was observed under scanning electron microscope for evaluating size of dentin chips, root canal surface recessions and smear layer. Scores of Smear layer were statistically analyzed using Kruskal Wallis test and Mann Whitney test at P = 0.05 level. Results: The size of dentin chips from ProFile, ProTaper and WaveOne was up to $7{\mu}m$, $6.5{\mu}m$, and$4{\mu}m$, respectively. In the surface profile, the width of surface irregularity was measured and Profile, ProTaper and WaveOne was up to $150{\mu}m$, $70{\mu}m$, and $80{\mu}m$, respectively. Completely cleaned root canals were not found. In the middle and apical third of the canals, WaveOne group showed higher smear layer score than ProFile and ProTaper groups (P < 0.05). Conclusion: Within limits of this study, reciprocating motion WaveOne group was not significant difference of shaping ability with the full-sequence ProFile and ProTaper systems except canal clearness of middle and apical third of root canal. When using WaveOne to shaping root canal, thorough root canal irrigation is recommended.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2005.09a
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• pp.201-212
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• 2005

[ $Epoxy/BaTiO_3$ ] composite embedded capacitor films (ECFs) were newly designed fur high dielectric constant and low tolerance (less than ${\pm}15\%$) embedded capacitor fabrication for organic substrates. In terms of material formulation, ECFs are composed of specially formulated epoxy resin and latent curing agent, and in terms of coating process, a comma roll coating method is used for uniform film thickness in large area. Dielectric constant of $BaTiO_3\;&\;SrTiO_3$ composite ECF is measured with MIM capacitor at 100 kHz using LCR meter. Dielectric constant of $BaTiO_3$ ECF is bigger than that of $SrTiO_3$ ECF, and it is due to difference of permittivity of $BaTiO_3\;and\;SrTiO_3$ particles. Dielectric constant of $BaTiO_3\;&\;SrTiO_3$ ECF in high frequency range $(0.5\~10GHz)$ is measured using cavity resonance method. In order to estimate dielectric constant, the reflection coefficient is measured with a network analyzer. Dielectric constant is calculated by observing the frequencies of the resonant cavity modes. About both powders, calculated dielectric constants in this frequency range are about 3/4 of the dielectric constants at 1 MHz. This difference is due to the decrease of the dielectric constant of epoxy matrix. For $BaTiO_3$ ECF, there is the dielectric relaxation at $5\~9GHz$. It is due to changing of polarization mode of $BaTiO_3$ powder. In the case of $SrTiO_3$ ECF, there is no relaxation up to 10GHz. Alternative material for embedded capacitor fabrication is $epoxy/BaTiO_3$ composite embedded capacitor paste (ECP). It uses similar materials formulation like ECF and a screen printing method for film coating. The screen printing method has the advantage of forming capacitor partially in desired part. But the screen printing makes surface irregularity during mask peel-off, Surface flatness is significantly improved by adding some additives and by applying pressure during curing. As a result, dielectric layer with improved thickness uniformity is successfully demonstrated. Using $epoxy/BaTiO_3$ composite ECP, dielectric constant of 63 and specific capacitance of 5.1nF/cm2 were achieved.

• Restorative Dentistry and Endodontics
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• v.17 no.2
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• pp.307-330
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• 1992

The aim of this study was to investigate the physical properties of visible light curing Glass Ionomer cement for restorative esthetic filling. The control group was the autopolymerizing GC Fuji II Glass Ionomer cement (2.2: 1 P/L ratio) and the experimental groups were made by following procedure. To induce the polymerization by visible light, the powder of GC Fuji II GI cement and the liquid of Vitrabond for base & liner were mixed in an amalgam capsule with 2.5:1, 3.0:1, 3.5:1 P/L ratio (% wt/wt). After fabrication of specimens, compressive strength, fracture toughness ($K_{IC}$) Scanning Electron Microscope and X-ray Diffraction, water-leachable content, marginal leakage and surface roughness were studied. The results were as follows: 1. Only experimental No. 1 group (visible light curing) showed less compressive strength than control group 1 hour after curing. Strength was increased with aging in all groups, so the compressive strength of light curing groups was no less than that of autopolymerizing group after 3 weeks. 2. Experimental No.3 group (visible light curing) was inferior to No.2 group (visible light curing) in fracture resistance but light curing groups were more resistant to fracture than autopolymerizing group and showed ductile fracture pattern as compared with the brittle fracture pattern of autopolymerizing group. 3. From scanning electron microscopic image, various sized unreacted powder particles, surrounded by silica gel, were embedded in polysalt matrix. Light curing groups showed little crack and more dense unreacted particles than autopolymerizing group. 4. From X-ray diffraction analysis, GC Fuji II Glass Ionomer cement powder and all groups showed glassy appearance but light curing groups seemed to be more intensive in crystaline than autopolymerizing group. S. The most significant dissolution was shown in early setting period in all group. Light curing groups were dissolved less than autopolymerizing group. 6. Marginal leakage was not different significantly in case of cavity margin composed of same tooth structure (ex. only enamel margin, only dentin margin) but much more leakage was shown in dentin/cementum margin than enamel margin. In only case of only enamel margin, light curing groups were superior to autopolymerizing group. 7. All groups showed relatively smooth surface, which irregularity was less than $1{\mu}m$. Light curing groups were smoother than autopolymerizing group.

• Korean Journal of Remote Sensing
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• v.14 no.4
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• pp.325-342
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• 1998

Two RADARSAT SAR images with different modes acquired by Canadian Space Agency to test the effectiveness of geological lineament extraction and spring water detection over the Cheju Island. Geological lineaments are poorly developed this basalt dominant volcanic island, but more linear features can be extracted when SAR and TM images are simultaneously analyzed than when TM image alone is used. This results mainly owe to the facts that RADARSAT SAR systems are able to provide data with different frequencies, azimuth, and incidence angles. Distribution of spring water along coast is poorly correlated with geological lineaments or drainage pattern, but those in middle range of mountain region are developed along geological lineaments. Detection of spring water using remotely sensed images are turned out to be very difficult to achieve. Radial shaped sea surface temperature anomaly derived from TM thermal band should be the best candidate for spring water, but the resolution is not high enough. We also investigate the normalized radar cross section (or sigma naught) converted from RADARSAT and ERS-1 SAR data but to discriminate the spring water effectively except where relatively large water mass is observed on land side. Speckle noise and irregularity in physical sea surface condition are the serious obstacles for this application. ERS-1 SAR image acquired in low incidence angle was more useful for geological lineament estimation and water body study than RADARSAT SAR images with high incidence angles. Therefore the selection of incidence angle is critical in geological and spring water applications of SAR images, and low incidence angles less than about 30$^{\circ}$ are recommended to monitor the Cheju volcanic island.