• Corrosion Science and Technology
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• v.12 no.4
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• pp.163-170
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• 2013

In NaCl solutions acidified with $H_2SO_4$, Fe20Cr1.1N alloy showed enhanced pitting corrosion resistance than Fe20Cr alloy. An XPS analysis revealed that the passive film of Fe20Cr1.1N alloy contained higher cationfraction of Cr than that of Fe20Cr alloy, and nitrogen was incorporated into the film. In addition, it was found that the passive film of Fe20Cr1.1N alloy was thinner and had higher oxygen vacancy density than that of Fe20Cr alloy. Based on these observations, it was concluded that the chemical composition was the determining factor for the protectiveness of the passive film of Fe20Cr based alloy in dilute $H_2SO_4$ solution.

• The Journal of Korean Physical Therapy
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• v.25 no.5
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• pp.260-265
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• 2013

Purpose: This study was conducted in order to evaluate the quantitative effectiveness of region of interest (ROI) setting in MR-DTI analysis with and without fMRI activation results. Methods: Ten right-handed normal volunteers participated in this study. DTI and fMRI datasets for each subject were obtained using a 1.5T MRI system. For neural fiber tracking, ROIs were drawn using two methods: The drawing points were located in the fMRI activation areas or areas randomly selected by users. In this study, the neural fiber tract targeted the corticospinal tract (CST) Quantitative analyses were performed and compared. The pixel numbers passing through the fiber tract in the individual brain volume were counted. The ratios between the ROI pixel numbers and the extracted fiber pixel numbers, and the ratios between the fiber pixel numbers and the whole-brain pixel numbers were also calculated. Results: According to our results, extracted CST fiber tract in which the ROI was drawn with fMRI activation areas showed higher distribution than drawing the ROI by users' hands. In addition, the quantitatively measured values represented higher pixel distribution: The counted average pixel numbers were 4553.8 and 1943.3. The average ratios of the ROI areas were 33.87 and 22.52. The average percentages of the individual whole-brain volume numbers were 2.06 and 0.87. Conclusion: Results of this study appear to indicate that use of this method can allow for more objectives and significant for study of the recovery of neural fiber mechanisms and brain rehabilitation.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.4
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• pp.147-158
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• 2017

PURPOSE: Balance exercise as well as lower extremity strengthening exercise (LESE) is known to be effective in patients with knee osteoarthritis (KOA). The purpose of this study was to investigate the effectiveness of performing LESE in conjunction with balance exercise on lower extremity function, range of motion, muscle strength, and balance in patients with KOA. METHODS: The subjects of this study were 25 patients with KOA who were recruited and randomly divided into two groups: 1) those who performed LESE with balance exercise; and 2) those who performed only LESE. Both the groups also received general physical therapy and performed aerobic exercise. The interventions were performed 3 times a week for 4 weeks. To determine the effectiveness of the interventions, we measured Western Ontario and MacMaster Universities Arthritis Index (WOMAC) score, numerical rating scale (NRS) score, passive range of motion (PROM), chair stand test (CST), and Berg Balance Scale (BBS) score at the initiation of the interventions and again after 4 weeks, at the time of completion of the interventions. RESULTS: After 4 weeks of the interventions, both the groups showed significantly improved WOMAC (p<.01), NRS (p<.01), PROM (p<.05), CST (p<.05), and BBS (p<.01) scores. However, there was no significant difference between the groups in terms of the clinical outcomes observed. CONCLUSION: These results suggest that the addition of balance exercise to a LESE regimen in patients with KOA did not provide any additional benefit.

• Journal of Korea Multimedia Society
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• v.1 no.2
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• pp.249-255
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• 1998

This paper analyzes the impact of Call Setup Time on UPT performance based on the AIN platform. Call Setup Time is used as the performance parameter. In implementing UPT based on the AIN platform, the geographical location of VLR affects network performance. In order to find an optimum location of VLR among three different types of structures, i.e. VLR is located close to Service Switching Point and Cell Site Controller and located at Service Control Point, each Call Setup Time on proposed time delay model is calculated and compared. Network performance is analyzed by changing the number of STP in No.7 signaling network in UPT and the utilization ratio, $\rho$, for SSP, STP and SCP.

• Journal of Urban Science
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• v.8 no.1
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• pp.45-49
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• 2019

The land treatment of sewage sludge is necessary because sewage sludge is increasing year by year. Therefore the research of sewage sludge solidification is underway as one of the land treatment methods. However, the problem with existing sewage sludge solidification is that the moisture content of sewage sludge is high and the dewaterability is low. Because of high drying cost the efficiency of energy production is low and the calorific value is insufficient. So the disposer is supplied with a filtration and caloric aid for improving dewaterability and calorific value. In this study, it is aimed to improve the fuel value of sewage sludge by confirming the feasibility of waste wood as a filtration and caloric aid. The dewaterability was measured by CST-test and the calorific value was measured by bomb calorimeter. As a result the dewaterability and calorific value are improved in all of the samples. The dewaterability was improved as the waste wood was added in the sewage sludge. By adjusting the waste wood adding rate into the sewage sludge the dewaterability and calorific value of sewage sludge will be improved. This study confirmed possibility of the waste wood used as filtration and caloric aid.

• Corrosion Science and Technology
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• v.15 no.1
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• pp.1-5
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• 2016

Zinc ethyl silicate coatings containing multi walled carbon nanotubes (MWCNTs) were prepared, to which we added spherical and flake shaped zinc particles. The anti-corrosive effects of MWCNTs and zinc shapes on the zinc ethyl silicate coated carbon steel was examined, using electrochemical impedance spectroscopy and corrosion potential measurement. The results of EIS and corrosion potential measurement showed that the zinc ethyl silicate coated with flake shaped zinc particles and MWCNT showed lesser protection to corrosion. These outcomes were in agreement with previous results of corrosion potential and corrosion occurrence.

• Corrosion Science and Technology
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• v.20 no.1
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• pp.1-6
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• 2021

Many Korean industrial plants including nuclear and fossil power plants use seawater as the ultimate heat sink to cool the heat generated by various facilities. Owing to the high corrosivity of seawater, facilities and piping made of metal material in contact with seawater are coated or lined with polymeric materials to avoid direct contact with seawater. However, polymeric materials used as coating and lining have some level of permeability to water and are degraded over time. Korean industrial plants have also experienced a gradual increase in the frequency of damage to pipes in seawater systems due to prolonged operating periods. In the event of a cavitation-like phenomenon, coating or lining inside the piping is likely to be damaged faster than expected. In this paper, the cause of water leakage due to base metal damage caused by the failure of the polyester lining in seawater system piping was assessed and the experience with establishing countermeasures to prevent such damage was described.

• Corrosion Science and Technology
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• v.21 no.1
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• pp.21-31
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• 2022

Potentiodynamic polarization, EIS measurements, quantum chemical calculations, and molecular dynamic simulations were used to investigate the corrosion behavior of mild steel in 0.5 M aqueous hydrochloric acid medium in the presence or absence of nystatin drug. Potentiodynamic tests suggested that this molecule could act as a mixed inhibitor due to its adsorption on the mild steel surface. The objective of this study was to exploit theoretical calculations to gain a better understanding mechanism of inhibition. Calculating the adsorption behavior of the investigated molecule on Fe (1 1 0) surface was accomplished using Monte Carlo simulation. Molecules were also investigated using Density Functional Theory (DFT), specifically PBE functional, in order to identify the link between molecular structure and corrosion inhibition behavior of the compound under investigation. Adsorption energies between nystatin and iron were estimated more accurately by utilizing Molecular Mechanics calculation with Periodic Boundary Conditions (PBC). Estimated theoretical parameters significantly assisted our understanding of the corrosion inhibition mechanism exhibited by this molecule. They were found to be in accord with experimental results.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.79-83
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• 2003

Multi-port($2{\times}2$port, 1port) rectangular waveguide discontinuity problem has been analyzed by use of $TE^x_{mn}$ (mono)mode matching method. Matrix size can be reduced significantly in comparison with $TE_{mn}&TM_{mn}$(full-wave)mode matching method. the present results is compared with those by CST MicroWave Studio to validate the presint method.

• Corrosion Science and Technology
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• v.9 no.1
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• pp.29-33
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• 2010

Laser machining technique, which is used focusing pulse YAG laser beam irradiation was applied to form area ratio controlled model cut-edge on pre painted Zn coated steels. A corrosion behavior of formed model cut-edge was investigated by rest potential measurement in 1 mol $m^{-3}$ NaCl with and without 0.5 kmol $m^{-3}$ $H_3BO_4$/0.05kmol$m^{-3}$ $Na_2B_4O_7$. The rest potential showed almost constant value with fluctuations. The amplitude of fluctuations increased with exposed area of steel surface. White corrosion products of zinc oxide and simonkollite was formed after the experiments at the formed model cut-edge.