• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.492-498
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• 2021

This feasibility study evaluated an optically transparent planar antenna using liquid salt-water as the conducting material. The most significant reason behind using liquid salt-water for transparent antenna applications is its excellent average optical transparency (OTav) (> 95% at a salinity of 40 ppt) compared to other typical solid transparent thin-film electrodes, such as indium tin oxide (ITO:> 73%) or multi-layer films (MLF: > 78%). Each conductive arm of the proposed dipole is constructed from a salt-water layer held between two clear planar acrylic layers (��r = 2.61, tan�� = 0.01, OTav > 90%) (acrylic/salt-water/acrylic; ASA) due to surface tension. To examine the electrical and optical properties of the ASA structure, the surface tension was measured to determine the thickness of the salt-water layer that finalized its sheet resistance and OTav. The average gain and efficiency of the antenna were 1.72 dBi and 74%, respectively, in the operating UHF (Ultra high frequency) band (470-771 MHz). Therefore, the proposed antenna can be a good candidate for applications as a transparent planar antenna using salt-water.

• Journal of the Korean institute of surface engineering
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• v.51 no.4
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• pp.224-230
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• 2018

In this study, Mg films were prepared on hot dip aluminized steel (HDA) by using a sputtering method as a high corrosion resistance coating. The corrosion resistance of the Mg films was improved by controlling the morphology and the crystal structure of films by adjusting the Ar gas pressure during the coating process. Anodic polarization measurement results confirm that the corrosion resistance of the Mg films was affected by surface morphology and crystal structure. The corrosion resistance of the Mg coated HDA specimen increased with decreasing crystal size of the Mg coating and it was also improved by forming a film with denser morphology. The crystal structure oriented at Mg(101) plane showed the best corrosion resistance among crystal planes of the Mg metals, which is attributed to its relatively low surface energy. Neutral salt spray test confirmed that corrosion resistance of HDA can be greatly improved by Mg coating, which is superior to that of HDG (hot dip galvanized steel). The reason for the improvement of the corrosion resistance of Mg films on hot dip aluminized steel was due to the barrier effect by the Mg corrosion products formed by the corrosion of the Mg coating layer.

• Korean Journal of Food Science and Technology
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• v.46 no.1
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• pp.100-107
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• 2014

We evaluated preventive effects of Suaeda japonica (SJ) and Spergularia marina Griseb (SMG) on the insulin resistance in Otsuka Long-Evans Tokushima Fatty (OLETF) rats. The 10-week old OLETF rats were fed diets containing 3% (w/w) SJ and SMG for 18 weeks. Fasting blood glucose levels in SJ and SMG groups, measured using the oral glucose tolerance test, were lower than that of the control rats. The SMG group showed significantly lower levels of insulin, glycated hemoglobin, triglyceride, and total cholesterol than the control group. In addition, these levels were relatively lower in the SJ group than those in the control rats. The SJ and SMG groups had relatively lower protein levels of nuclear factor-kappa B (NF-${\kappa}B$) p65 in adipose tissue and serine phosphorylated insulin receptor substrate 1 (IRS-1) in skeletal muscle than the control group. These results suggest that SJ and SMG prevent insulin resistance and SMG in particular reduces blood triglyceride and total cholesterol levels.

• Corrosion Science and Technology
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• v.8 no.5
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• pp.203-207
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• 2009

Electrochemical methods have been widely used to study the performances and mechanisms for the degradation of organic and inorganic coatings. In this study, EN(Electrochemical noise) measurement was applied to the protective properties and review the parameters analyzed noise signals in the time and in the frequency domain for epoxy resin based coated steels during exposure to hot sea water($40^{\circ}C$) and salt spray for 200 days. It was also found that $R_n$(Noise resistance), $R_{sn}$($f_{min}$)(Spectral noise resistance) and 2H(Hurst exponent) represented the performance of epoxy coated steels. $R_n$ can be determined as the ratio of the standard deviations of potential and current noise signals and is decreased to exposure time. Data qualities can be easily checked by PSD(Power Spectral Density) plot and $V_{psd}$, $I_{psd}$ and $R_{sn}$($f_{min}$) is useful to research the protective performances and mechanisms of coated steels. Hurst exponent represents the degradation of coated steels. But, it is difficult to directly apply the protective criterion to the evaluation of epoxy coated steels used the shipbuilding processes.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.91-91
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• 2011

The quality of the surface layer in concrete structures plays an important role in the durability of the concrete. The concrete factory products are made as they improve the appearance of the surface and compressive strength in need. A common criterion to judge the quality of concrete products frequently seen in our daily life appears to be "beauty" in terms of consistent shaping. However, as for most concrete curb in such areas where a large amount of anti-freezing agents(NaCl) and ice and snow melting agents(CaCl2) are spread over roads to ensure road safety during the winter season, since deterioration advances from the surface, scaling is seen on the surface concrete due to deterioration which combined freezing damage and salt damage. Especially, In cold northern districts, the spreading amount of deicing salts increases by regulation of studded tire use, and the scaling of the concrete products, the various parts of concrete structures for roads is increasing in recent years. In this study, L-shape concrete curb were targeted, the permeable form method with the commercial permeable sheet was applied to it and the improvements of the quality were examined. By the permeable form method, surface layers got strengthened, which prevented permeation of the deterioration factor from the outside, and the scaling resistance of the upper surface where the permeable sheet was applied improved exceedingly. It will be expected by applying the permeable form method to various concrete products that frost resistance improves and scaling damage decreases.

• Korean Journal of Materials Research
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• v.16 no.8
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• pp.461-465
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• 2006

Chromium (Cr) films were deposited on plain carbon steel sheets by DC and RF magnetron sputtering as well as by electroplating. Effects of DC or RF sputtering power on the deposition rate and properties such as, hardness, surface roughness and corrosion-resistance of the Cr films were investigated. X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microcopy (SEM) analyses were performed to investigate the crystal structure, surface roughness, thickness of the Cr films. Salt fog tests were used to evaluate the corrosion resistance of the samples. The deposition rate, hardness, and surface roughness of the Cr film deposited by either DC or RF sputtering increase with the increase of sputtering power but the adhesion strength is nearly independent of the sputtering power. The deposition rate, hardness, and adhesion strength of the Cr film deposited by DC sputtering are higher than those of the Cr film deposited by RF sputtering, but RF sputtering offers smoother surface and higher corrosion-resistance. The sputter-deposited Cr film is harder and has a smoother surface than the electroplated one. The sputter-deposited Cr film also has higher corrosion-resistance than the electroplated one, which may be attributed to the smoother surface of the sputter-deposited film.

• Journal of Magnetics
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• v.16 no.3
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• pp.304-307
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• 2011

High performance Nd-Fe-B magnets can be manufactured by both sintering and hot deformation. The corrosion behaviors of the magnets prepared by the two processes were compared. Effect of microstructure on the corrosion resistance of Nd-Fe-B magnets was also investigated. A neutral salt spray test (NSS) was performed for the different-processed magnets. The weight losses of the samples after the corrosion test were measured. The corrosion microstructures were observed using a scanning electron microscope. It shows that the corrosion resistance of hot deformed magnets is much better than that of the sintered ones because the grain size and the distribution of Nd-rich phases of the hot deformed magnets are much finer and more uniform than those of the sintered ones. The different microstructure between the sintered and the hot deformed magnets causes the different corrosion behavior.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.227-233
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• 2008

Porous concrete has large continuous voids of 20-30 % by volume, and this concrete is attractive as environmental material in Japan i.e. permeable road pavement, river bank protection with vegetation and green roof system which influence thermal environment. It is necessary to confirm the frost resistance when constructing porous concrete structure in cold region. However applicable test method and evaluation criterion of porous concrete has not defined yet. Therefore, the object of this study is to investigate the frost resistance of porous concrete and this investigation attempts to address this concern by comparing 4 kinds of specified freezing and thawing tests methods (JIS A1148 procedure A/B and RILEM CIF/CDF test) in consideration of actual environment. RILEM freeze-thaw tests are different from JIS A1148 freeze-thaw tests, which are widely adopted for evaluating the frost resistance of conventional concrete in Japan, in water absorption, cooling rate, length of freezing and thawing period, and number of freezing and thawing cycles. RILEM CIF test measures internal damage and is primarily applicable for pure frost attack. CDF test is appropriate for freeze-thaw and de-icing salt attack. JIS A1148 procedure A/B showed extremely low frost resistance of porous concrete if the large continuous voids were filled with water and the ice expansion in the large continuous voids set in during cooling. Frost resistance of porous concrete was improved by mixing coarse aggregate (G7) which particle size is smaller and fine aggregate in JIS freezing and thawing tests. RILEM CIF/CDF test showed that freeze-thaw and de-icing resistance of porous concrete was seems to be superior in that of conventional concrete.

• Journal of Microbiology and Biotechnology
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• v.32 no.12
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• pp.1537-1546
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• 2022

Staphylococcus aureus is a cause of high mortality in humans and therefore it is necessary to prevent its transmission and reduce infections. Our goals in this research were to investigate the frequency of methicillin-resistant S. aureus (MRSA) in Taif, Saudi Arabia, and assess the relationship between the phenotypic antimicrobial sensitivity patterns and the genes responsible for resistance. In addition, we examined the antimicrobial efficiency and application of silver nanoparticles (AgNPs) against MRSA isolates. Seventy-two nasal swabs were taken from patients; MRSA was cultivated on Mannitol Salt Agar supplemented with methicillin, and 16S rRNA sequencing was conducted in addition to morphological and biochemical identification. Specific resistance genes such as ermAC, aacA-aphD, tetKM, vatABC and mecA were PCR-amplified and resistance plasmids were also investigated. The MRSA incidence was ~49 % among the 72 S. aureus isolates and all MRSA strains were resistant to oxacillin, penicillin, and cefoxitin. However, vancomycin, linezolid, teicoplanin, mupirocin, and rifampicin were effective against 100% of MRSA strains. About 61% of MRSA strains exhibited multidrug resistance and were resistant to 3-12 antimicrobial medications (MDR). Methicillin resistance gene mecA was presented in all MDR-MRSA strains. Most MDR-MRSA contained a plasmid of > 10 kb. To overcome bacterial resistance, AgNPs were applied and displayed high antimicrobial activity and synergistic effect with penicillin. Our findings may help establish programs to control bacterial spread in communities as AgNPs appeared to exert a synergistic effect with penicillin to control bacterial resistance.

• Journal of fish pathology
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• v.28 no.2
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• pp.71-78
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• 2015

In this study, we conducted to the development of a rapid antimicrobial susceptibility test method using WST-1 which is known to water-soluble tetrazolium salt, in order to rapidly response against bacterial diseases in fish. Eight of antibiotics which are permissioned for marine organism from government were used to rapid antimicrobial susceptibility testing using the WST-1. As a result, a similar tendency was verified compare to conventional antibiotic susceptibility test results. Generally, the antibiotic susceptibility test method required about 3 days (72 hours) for determine the effective antibiotics, however, we have confirmed that the our method using WST-1 was required at least 36 hours in this study. Consequentially, our method will contribute to development of rapid antimicrobial susceptibility testing for bacterial diseases in fish.