• Nuclear Engineering and Technology
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• v.46 no.6
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• pp.869-874
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• 2014

It was discovered in a Korean PWR that an extensive number of very short and shallow cracks in the SG tubes were undetectable by eddy current in-service-inspection because of the masking effect of sludge deposits. Axial stress corrosion cracks at the outside diameter of the steam generator tubes near the line contacts with the tube support plates are the major concern among the six identical Korean nuclear power plants having CE-type steam generators with Alloy 600 high temperature mill annealed tubes, HU3&4 and HB3~6. The tubes in HB3&4 have a less susceptible microstructure so that the onset of ODSCC was substantially delayed compared to HU3&4 whose tubes are most susceptible to ODSCC among the six units. The numbers of cracks detected by the eddy current inspection jumped drastically after the steam generators of HB4 were chemically cleaned. The purpose of the chemical cleaning was to mitigate stress corrosion cracking by removing the heavy sludge deposit, since a corrosive environment is formed in the occluded region under the sludge deposit. SGCC also enhances the detection capability of the eddy current inspection at the same time. Measurement of the size of each crack using the motorized rotating pancake coil probe indicated that the cracks in HB4 were shorter and substantially shallower than the cracks in HU3&4. It is believed that the cracks were shorter and shallower because the microstructure of the tubes in HB4 is less susceptible to ODSCC. It was readily understood from the size distribution of the cracks and the quantitative information available on the probability of detection that most cracks in HB4 had been undetected until the steam generators were chemically cleaned.

• Applied Biological Chemistry
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• v.28 no.2
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• pp.98-105
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• 1985

In the sheep and cattle's rumen, facultative anaerobic cellulolytic bacteria were isolated by using Hungate's roll tube technique. In the 21 isolated species, one was screened by its strong cellulolytic activity and identified as Cellulomonas fimi C-14 by investigate morphological, cultural, physiological characteristics and electron microgram. Optimum conditions of the cell growth and enzyme production were pH 6.5 an $30^{\circ}C$, Thiamine and biotin support a good growth of C. fimi C-14. In the enzyme activities, Crystalline cellulose hydrolyzing activity, CMCase activity and ${\beta}-glucosidase$ activity were 20.6, 226.6 and 0.56$(unit{\times}10^3/ml)$ at pH 6.0, $40^{\circ}C$. By addition of fungal cellulase, enzyme activity was increased. Simultaneous Saccharification Fermentation is better than two step fermentation in ethanol yield with Saccharomyces cerevisiae DY2.

• Bulletin of the Korean Chemical Society
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• v.24 no.12
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• pp.1775-1780
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• 2003

A continuous flow system has been developed to determine trace Cu(II), Mn(II), Ni(II) and Zn(II) in a large volume of water samples by a solvent sublation technique. The mixed solution of 1,10-phenanthroline(phen) and thiocyanate ion was used as ligands for the formation of their ternary complexes. The continuous system was constructed in this laboratory with a peristaltic pump, a mini shaker, three mixing bottles and a flotation cell by connecting each part with a polyethylene tube. The flotation conditions such as the flow rate of sample solution and the injection rates of ligand, buffer and surfactant solutions have been investigated to obtain the best sublation efficiencies. Each solution flowed into the flotation cell through each polyethylene tube by the peristaltic pumps. The ternary complexes were floated and extracted into MIBK in a flotation cell of 2 L by bubbling a nitrogen gas. The absorbances of extracted analytes in MIBK were directly measured by graphite furnace-AAS. The concentrations of 1,10-phenanthroline and thiocyanate ion were $2.6\;{\times}\;10^{-3}$ M and $2.3\;{\times}\;10^{-2}$ M in the mixed solution, respectively. The pH of sample solution was adjusted to 5.0 with a buffer solution and 1%(m/v) sodium lauryl sulphate solution was added as a surfactant to support the effective flotation of the complexes. The $N_2$ gas was bubbled at 30 mL/min for 90 minutes for 20 L of sample. Reproducible results of less than 10% RSD and recoveries of 80-120% could be obtained in real samples.

• Imaging Science in Dentistry
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• v.42 no.3
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• pp.163-167
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• 2012

Purpose: ANSI/ADA has established standards for adequate radiopacity. This study was aimed to assess the changes in radiopacity of composite resins according to various tube-target distances and exposure times. Materials and Methods: Five 1-mm thick samples of Filtek P60 and Clearfil composite resins were prepared and exposed with six tube-target distance/exposure time setups (i.e., 40 cm, 0.2 seconds; 30 cm, 0.2 seconds; 30 cm, 0.16 seconds, 30 cm, 0.12 seconds; 15 cm, 0.2 seconds; 15 cm, 0.12 seconds) performing at 70 kVp and 7 mA along with a 12-step aluminum stepwedge (1 mm incremental steps) using a PSP digital sensor. Thereafter, the radiopacities measured with Digora for Windows software 2.5 were converted to absorbencies (i.e., A=-log (1-G/255)), where A is the absorbency and G is the measured gray scale). Furthermore, the linear regression model of aluminum thickness and absorbency was developed and used to convert the radiopacity of dental materials to the equivalent aluminum thickness. In addition, all calculations were compared with those obtained from a modified 3-step stepwedge (i.e., using data for the 2nd, 5th, and 8th steps). Results: The radiopacities of the composite resins differed significantly with various setups (p<0.001) and between the materials (p<0.001). The best predicted model was obtained for the 30 cm 0.2 seconds setup ($R^2$=0.999). Data from the reduced modified stepwedge was remarkable and comparable with the 12-step stepwedge. Conclusion: Within the limits of the present study, our findings support that various setups might influence the radiopacity of dental materials on digital radiographs.

• Membrane Journal
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• v.11 no.3
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• pp.124-132
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• 2001

Silica membranes were prepared on a porous ${\alpha}$-alumina tube with pore size of 150nm by sol-gel and chemical vapor deposition(CVD) method for hydrogen separation at high temperatures. Silica and ${\gamma}$-lumina membranes formed by the sol-gel method possessed a large amount of mesopores of a Knudsen diffusion regime. In order to improve the $H_2$ selectivity, silica was deposited in the sol-gel derived silica/${\gamma}$-alumina layer by thermal decomposition of tetraethyl orthosilicate(TEOS) at $600^{\circ}C$. The CVD with forced cross flow through the porous wall of the support was very effective in plugging mesopores that were left unplugged in the membranes. The CVD modified silica/alumina composite membrane completely rejected nitrogen permeation and thus showed a high $H_2$ selectivity by molecular sieve effect. the permeation of hydrogen was explained by activated diffusion and the activation energy was 9.52kJ/mol.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.5
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• pp.545-550
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• 2012

Steam generator is one of the major components of nuclear power plant and steam generator tubes are the pressure boundary between primary and secondary side, which makes them critical for nuclear safety. As the operating time of nuclear power plant increases, not only damage mechanisms but also scaled deposits on steam generator tubes are known to be problematic causing tube support flow hole blockage and heat fouling. The ability to assess the extent and location of scaled deposits on tubes became essential for management and maintenance of steam generator and eddy current bobbin data can be utilized to measure thickness of scale on tubes. In this paper, tube reference standards with various thickness of scaled deposit has been set up to provide information about the overall deposit condition of steam generator tubes, providing essential tool for steam generator management and maintenance to predict and prevent future damages. Also, methodology to automatically measure scale thickness on tubes has been developed and applied to field data to estimate overall scale amount.

• Journal of Coastal Disaster Prevention
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• v.4 no.3
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• pp.111-118
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• 2017

In this study, pull box members were designed by finite element analysis of a steel plate covering a pull box to secure its safety on the landing pier dedicated to the large research survey ship. It was assumed that the maximum load is due to the 250 tonf class crane used for unloading work when the working environment in the upper part of the landing pier was considered. The safety of the pull box was evaluated by the comparison between the yield strength of the steel plate and the result of stress analysis on the steel plate due to the crane load. It was found that the stress at the plate from the crane load exceeded the yield strength of the steel(205MPa) when the upper part of the pull box was protected by a $1950{\times}1950mm$ steel plate cover. In order to compensate for this, a concrete filled steel tube(CFT) column with a diameter of 150 mm and a steel thickness of 10 mm was reinforced at the center of the plate, and the finite element analysis was carried out. However, the maximum stress at the steel plate was higher than the yield strength of the steel in some load cases so that it was tried to find appropriate thickness of the steel plate and diameter of the CFT columns. Finally, the analysis results showed that the safety of the pull box was secured when the thickness of the steel plate and the diameter of the CFT column were increased to 30mm and 180mm, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.11
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• pp.1321-1329
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• 2019

With the development of social information networks, the marketing methods are also changing in various ways. Unlike successful marketing methods based on existing celebrities and financial support, Influencer-based marketing is a big trend and very famous. In this paper, we first extract influencer features from more than 54 YouTube channels using the multi-dimensional qualitative analysis based on the meta information and comment data analysis of YouTube, model representative themes to maximize a personalized video satisfaction. Plus, the purpose of this study is to provide supplementary means for the successful promotion and marketing by creating and distributing videos of new items by referring to the existing Influencer features. For that we assume all comments of various videos for each channel as each document, TF-IDF (Term Frequency and Inverse Document Frequency) and LDA (Latent Dirichlet Allocation) algorithms are applied to maximize performance of the proposed scheme. Based on the performance evaluation, we proved the proposed scheme is better than other schemes.

• Journal of Korean Physical Therapy Science
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• v.30 no.4
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• pp.9-16
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• 2023

Background: Bedridden patients and disabled persons need help from a guardian or caregiver even in performing simple activities of daily living. In particular, for body transfer of them, the use of a transfer lift has been recommended. However, the devices currently in use have limitations in terms of support according to the individual's characteristics. This study aimed to develop a transfer lift device utilizing the patients' body-fitting sling equipped with an air tube inside the sling. In addition, we have conducted usability tests to examine the safety, effectiveness, and satisfaction with this device. Design: This study conducted usability tests with 10 healthy adults. Methods: Customized sling lifts are generally floor-based devices that consisted of a sling that holds the patient's body and a lift that moves the sling to the desired position. One characteristic feature of the device is an air tube, which is used on the sling to allow the patient's body can be adjusted. A usability test was performed in terms of the operators, who operated the device to transfer the patients. Ten operators tried the device and tested its usability. Results: The mean of 10 question for Questions was 4.18. Conclusion: The device can be useful in the advance- ment and commercialization of customized sling lifts, to ensure the safe and efficient transfer of persons with disabilities.

• Tuberculosis and Respiratory Diseases
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• v.44 no.2
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• pp.329-337
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• 1997

Background : Since endotracheal tube is the most important factor involved in the imposed work of breathing during mechanical ventilation, extubation of endotracheal tube is supposed to reduce respiratory work of patient. However, some patients show labored breathing after extubation despite acceptable blood gases. We investigated the changes of work of breathing before and after extubation and the factors involved in the change of WOB after extubation. Methods : The subjects were 34 patients(M : F = 20 : 14, mean age = $61{\pm}17yre$) who recovered from respiratory failure after ventilatory support and were considered to be ready for extubation. The patients with clinical or radiologic evidences of upper airway obstruction before endotracheal intubation for mechanical ventilation were excluded. Vital sign, physical examination, chest X-ray, work of breathing and other respiratory mechanic indices were measured prior to, immediately, 6, 24 and 48 hours after extubation serially. Definition of weaning failure after extubation was resumption of ventilatory support or reintubation of endotracheal tube within 48 hour after extubation because of respiratory failure. The patients were classified into group 1(decreased work of breathing), group 2(unchanged work of breathing) and group 3(increased work of breathing) depending on the statistical difference in the change of work of breathing before and after extubation. Results : Work of breathing decreased in 33%(11/34, group 1), unchanged in 41%(14/34, group 2) and increased in 26%(9/34, group 3) of patients after extubation compared with before extubation. Weaning failure occurred 9%(1/11) of group, 1, 28.6%(4/14) of group 2 and 44%(4/9) of group 3 after extubation(p = 0.07). The change of work of breathing after extubation was positively correlated with change of mean airway resistance(mRaw). (r = 0.794, p > 0.01). In three cases of group 3 whose respiratory indices could be measured until 48 hr after extubation, the change in work of breathing paralleled with the sequential change of mRaw. The work of breathing was peaked at 6 hr after extubation, which showed a tendency to decrease thereafter. Conclusions : Reversible increase of work of breathing after extubation may occur in the patients who underwent extubation, and the increase in mRaw could be responsible for the increase in work of breathing. In addition, the risk of weaning failure after extubation may increase in the patients who have increased WOB immediately after extubation.