• KSBB Journal
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• v.32 no.2
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• pp.153-159
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• 2017

The purpose of this study was to investigate the probiotic properties of lactic acid bacterial strains isolated from human feces. The properties were tested on the basis of guideline for probiotic selection protocol such as tolerance for acid or bile salt, autoaggregation, antibiotic resistance, and antimicrobial activity. Total 25 lactic acid bacteria were isolated from human feces, and their antibacterial activity was tested against Staphylococcus aureus, Escherichia coli, E. coli O157:H7, Vibrio parahaemolyticus, V. alginolyticus using an agar diffusion assay. Among them, 4 selected strains were identified by analysis of their 16S rRNA, as Lactobacillus rhamnosus MG316, L. acidophilus MG501, L. reuteri MG505, and L. gasseri MG570. Results show that resistance to low pH and bile salts. Also, the selected strains were resistant to bile acid up to 3% and their autoaggregation rates were as high as 60%. All strains tested were resistance to nalidixic acid and kanamycin.

• Journal of Genetic Medicine
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• v.10 no.2
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• pp.81-87
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• 2013

Pseudohypoaldosteronism (PHA), a rare syndrome of systemic or renal mineralocorticoid resistance, is clinically characterized by hyperkalemia, metabolic acidosis, and elevated plasma aldosterone levels with either renal salt wasting or hypertension. PHA is a heterogeneous disorder both clinically and genetically and can be divided into three subgroups; PHA type 1 (PHA1), type 2 (PHA2) and type 3 (PHA3). PHA1 and PHA2 are genetic disorders, and PHA3 is a secondary disease of transient mineralocorticoid resistance mostly associated with urinary tract infections and obstructive uropathies. PHA1 includes two different forms with different severity of the disease and phenotype: a systemic type of disease with autosomal recessive inheritance (caused by mutations of the amiloride-sensitive epithelial sodium channel, ENaC) and a renal form with autosomal dominant inheritance (caused by mutations of the mineralocorticoid receptor, MR). In the kidneys, the distal nephron takes charge of the fine regulation of water absorption and ion handling under the control of aldosterone. Two major intracellular actors necessary for the action of aldosterone are the MR and the ENaC. Impairment of the intracellular aldosterone signal transduction pathway results in resistance to the action of mineralocorticoids, which leads to PHA. Herein, ion handling the distal nephron and the clinico-genetic findings of PHA are reviewed with special emphasis on PHA type 1.

• Korean Journal of Veterinary Service
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• v.22 no.1
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• pp.85-92
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• 1999

This study was investigated resistance on disinfectants and antibiotics of Clostridium chauvoei isolated from dairy farm in Kyongbuk province. The results obtained were summarized as follows ; C chauvoei isolated from dairy farm were susceptible to norfloxacin, penicillin, tetracycline, erythromycin, enrofloxacin, bacitracin, tyrosine, cephalothin and cefazolin but resistant to gentamicin, kanamycin, sulfamethoxazole＋trimethoprim, amikacin, neomycin streptomycin, colistin. In effect on disinfectants, C chauvoei was inhibited completely to growth in mercuric bichloride ($HgCl_2$), harasol(sodium hypochloride 4-6%), long-life(high boiling tar acids et al), and phenol($C_6$$H_5$OH), but growth in all-stop(didecyl dimethyl ammonium chloride 10%), powercide(potassium monopersulphate 50% et al), antec vercon-s(triple salt 50% et al), and taego-51(6-alkyl-2.6-diaza-hexane-carbonic acid-1ㆍHCl et al). The effect of disinfectant was excellent in mercuric bichloride and harasol.

• Journal of Surface Science and Engineering
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• v.50 no.4
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• pp.266-271
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• 2017

In this study, the corrosion resistance of Zn-3wt.%Mg coating was enhanced by controlling the density of coating. During the deposition the substrate temperature was controlled via an intermittent deposition process, resulting in the improvement of coating density. The maximum substrate temperature during this intermittent deposition process could be controlled from $200^{\circ}C$ to $80^{\circ}C$, depending upon the number of coating layer. The density of Zn-3 wt.%Mg coating increased from 76.1 % to 95.8 % as the substrate temperature was controlled. The salt spray test results revealed that the corrosion resistance of Zn-Mg coated steel could increase 3 times by increasing the density in coatings, while adhesion strength of coating was not changed significantly during 0-T bending test.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.239-242
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• 2009

As the high-rise building increase due to the gravitation of population to big cities recently, it requires high quality and high performance of Concrete. As a result, people are keenly interested in Meta-kaolin as new admixture favorable from an economic perspective, which has strength and endurance with admixture at the same level like Silica-fume. Accordingly, as to Meta-kaolin, this study was to set by three levels like domestic one, foreign one, and Silica-fume, the water-binding material ratio 25%, and four level substitute like 0, 10, 20, and 30(%) in order to compare and analyze the quality durability of high-concrete according to the substitute of Meta-kaolin applicable with replacement of Silica-fume. As a result of performing experiment it was found that when water-binding material ratio increases, resistance of neutralization, carbonation, salt damage and sulfate decrease, and when replacement ratio of mineral admixture increases, depth of accelerating carbonation gets greater. Also, the combination of SF and MK-B favored resistance to chloride ion penetration better than MK-A, and it was found that when replacement ratio of binding material increases, the resistance to sulphuric acid increases. Therefore, based on this study, it was understood that meta-kaolin is useable in replacement of silicafume.

• Journal of Korean Port Research
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• v.14 no.4
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• pp.475-479
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• 2000

A possibility of the implementation of a quartz crystal sensor to the determination of chemical oxygen demand is examined by checking the electrochemical behavior of the sensor in a glucose solution. Since the surface of a quartz crystal has to be oxidized, a relatively active metal is coated on the surface of a usual 9 MHz AT-cut crystal. The electrochemical behavior is investigated by measuring the changes of current, resonant frequency and resonant resistance while a constant potential is applied. The crystal is installed in a specially designed container, and a quartz crystal analyzer is utilized to measure the frequency and resistance simultaneously. The variations of the measurements are examined at different concentrations of glucose solution, and a proper relation between the concentrations of glucose solution, and a proper relation between the concentration and the measurements is analyzed. As a result, it is found that a linear relation between the concentration of less than 900 ppm and the peak current when a constant potential of -180 mV (SSCE) is applied. The relation can be utilized for the determination of glucose concentration in sea water, and considering a direct relation between gluose concentration and chemical oxygen demand tells a possibility of the measurement of chemical oxygen demand using quartz crystal oscillators.

• Journal of Surface Science and Engineering
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• v.51 no.6
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• pp.405-414
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• 2018

The present study investigated the adhesion and corrosion resistance of subsequent electrophoretic paint (E-paint) on "electroless" paint coated AZ31 Mg alloy, which was formed by immersion of AZ31 Mg alloy in E-painting solution. It was found that with increasing immersion time of AZ31 in E-painting solution, the amount of paint deposited by electroless process increased but it decreased the electrochemical equivalent of E-painting process and the adhesion of the subsequent E-paint layer. The E-paint on electroless paint coated AZ31 contained pores with the highest pore density and the largest pore size was obtained on the samples with electroless times of 2 and 5 minutes, respectively. Results of the salt-spray test showed an accelerated growth of blisters over the entire surface of the sample immersed for less than 5 minutes whereas blisters were observed only in the vicinity of the scratch in case of samples treated for 15 and 30 minutes. The E-paint on AZ31 with shorter electroless immersion time in E-painting solution was found to have good adhesion and better corrosion resistance.

• Korean Journal of Materials Research
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• v.29 no.5
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• pp.288-296
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• 2019

The passivation of AZ91D Mg alloys through plasma anodization depends on several process parameters, such as power mode and electrolyte composition. In this work, we study the dependence of the thickness, composition, pore formation, surface roughness, and corrosion resistance of formed films on the electrolyte temperature at which anodization is performed. The higher the electrolyte temperature, the lower is the surface roughness, the smaller is the oxide thickness, and the better is the corrosion resistance. More specifically, as the electrolyte temperature increases from 10 to $50^{\circ}C$, the surface roughness (Ra) decreases from 0.7 to $0.15{\mu}m$ and the corrosion resistance increases from 3.5 to 9 in terms of rating number in a salt spray test. The temperature increase from 10 to $50^{\circ}C$ also causes an increase in magnesium content in the film from 25 to 63 wt% and a decrease in oxygen from 66 to 21 wt%, indicating dehydration of the film.

• Journal of Power System Engineering
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• v.13 no.3
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• pp.33-39
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• 2009

The aim of this study is to analyze the welds characteristics of the 205 stainless steel pipe for application of street pole material. The welds corrosion behavior of STS 205 pipe in 0.1 N sulphuric acid solution and 5% NaCl solution at room temperature was studied using both salt spray test and potentiodynamic polarization experiment. The morphology and components of corrosion products on surface of STS 205 pipe welds were investigated using SEM/EDX. The tensile strength and yield strength values of STS 205 plate were 715 MPa and 369 MPa respectively. The microvickers hardness values of STS 205 pipe welds were slightly increased than that of STS 304 pipe welds. Corrosion current density($I_{corr.}$) and critical current density($I_{crit.}$) values of STS 205 pipe welds in 3.5% NaCl solution were $1.89{\times}10^{-6}$ $A/cm^2$ and $15.8{\times}10 ^{-6}$ $A/cm^2$. The corrosion resistance of SIS 205 pipe welds was similar to its STS 304 pipe welds. The STS 205 and 304 pipe welds passive films were chromium oxide. Especially, the STS 205 pipe welds showed good corrosion resistance in 0.1 N sulphuric acid. This is attributed to the forming of protective chromium oxide on the surface of STS 205 pipe welds.

• Korean Journal of Materials Research
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• v.22 no.5
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• pp.227-236
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• 2012

Ionomer is a thermoplastic that is composed of covalent bonds and ionic bonds. It is possible to use this material in processes such as injection molding or extrusion molding due to the material's high oil resistance, weatherproof characteristics, and shock resistance. In this study, a new ionomer having a multifunctional group was prepared by a stepwise neutralization system with the addition of acidic and salt additives. In step I, to increase the contents of the multifunctional group and the acid degree in ethylene acrylic acid (EAA), MGA was added to the ionomer resin (EAA). A new ionomer was prepared via the traditional preparation method of the ionic cross-linking process. In step II, metal salt was added to the mixture of EAA and MGA. The extrusion process was performed using a twin extruder (L/D = 40, size : ${\varphi}30$). Ionomer film was prepared for evaluation of gas permeability by using the compression molding process. The degree of neutralized and ionic cross-linked new ionomer was confirmed by FT-IR and XRD analysis. In order to estimate the neutralization of the new ionomer film, various properties such as gas permeation and mechanical properties were measured. The physical strength and anti-scratch property of the new ionomer were improved with increase of the neutralization degree. The gas barrier property of the new ionomer was improved through the introduction of an ionic site. Also, the ionic degree of cross-linking and gas barrier property of the ionomer membrane prepared by stepwise neutralization were increased.