• Economic and Environmental Geology
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• v.39 no.6 s.181
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• pp.719-738
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• 2006

Simrad EM950 multibeam data and surficial sediment grab samples were acquired to correlate backscatter strength with surficial sediment properties in the eastern Yellow Sea which tidal sand ridges are dominantly developed. The study area is divided into the western sand ridge zone characterized by well sorted, fine sandy sediment, and the eastern non-sand ridge zone characterized by poorly sorted, medium sand with some gravels and shell fragments. In spite of minor difference in grain size between two zones, the variations of backscatter strength between two zones are distinct. Multibeam backscatter strength of study area shows good correlation with the grain size of surface sediment as well as the carbonate contents. High occurrence of carbonate shell fragments can increase grain size and bottom roughness. The dominance of higher backscatter strength in the eastern non-sand ridge zone may reflect the effects of coarse grain size and high shell fragments contents.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.6
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• pp.685-691
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• 1996

This experiment was conducted to investigate the effect of some soil conditioners, such as polyvinylalcohol(PVA), zeolite and perlite, on the changes of soil physical properties and on tobacco growth in paddy-upland rotated field. Soil conditioners were treated at the rates of 120kg in PVA, 500kg in zeolite and perlite per l0a, respectively. Ratio of soil aggregates formed from the treated plots tended to. be higher than those from the control in the order of PVA > perlite > zeolite. The wet aggregate stability, mean weight diameter, moisture retention and air permeability from the treated plots tended to be higher than those from the control. Amounts of water-stable aggregates of PV A-treated soil increased with higher soil moisture showing a peak at 50% of moisture content. But with respect to particle of size aggregate formed for crop growth and workability in field, it was presumed that 40% of soil moisture content would be most desirable. Visual characters of soil surface throughout the experiment clearly showed that treated soils were maintaining better surface roughness and porosity than control, but difference in water stable aggregates among treated plots tended to be narrowed. The growths of tobacco, espacially its root zone were better in conditioner treated plots than in non-treated plot showing best in PVA-treated soil.

• Resources Recycling
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• v.26 no.6
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• pp.84-90
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• 2017

The electro-refining process was performed to recovery high purity copper from low grade copper containing sludge in sulfuric acid. The surface morphologies and roughness of electro-refining copper were analyzed with variation of the type and concentration of organic additives, the best surface morphology was obtained 5 ppm of the gelatin type and 5 to 10 ppm of the thiol type organic additive. The crude metal consisted of copper with 86.635, 94.969 and 99.917 wt.%, several impurity metals of iron, nickel, cobalt and tin by pyro-metallurgical process. After electro-refining process, the purity of copper increases to 3N or 4N grade. The impurity concentrations and copper purities of copper crude metals, electrolyte and electro-refining copper were analyzed using ICP-OES, the electro-refining time and purity of copper crude metal to recover 4N grade copper were deduced.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.169-169
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• 2010

As display industry requires various applications for future display technology, which can guarantees high level of flexibility and transparency on display panel, oxide semiconductor materials are regarded as one of the best candidates. $InGaZnO_4$(IGZO) has gathered much attention as a post-transition metal oxide used in active layer in thin-film transistor. Due to its high mobility fabricated at low temperature fabrication process, which is proper for application to display backplanes and use in flexible and/or transparent electronics. Electrical performance of amorphous oxide semiconductors depends on the resistance of the interface between source/drain metal contact and active layer. It is also affected by sheet resistance on IGZO thin film. Controlling contact/sheet resistance has been a hot issue for improving electrical properties of AOS(Amorphous oxide semiconductor). To overcome this problem, post-annealing has been introduced. In other words, through post-annealing process, saturation mobility, on/off ratio, drain current of the device all increase. In this research, we studied on the relation between device's resistance and post-annealing temperature. So far as many post-annealing effects have been reported, this research especially analyzed the change of electrical properties by increasing post-annealing temperature. We fabricated 6 main samples. After a-IGZO deposition, Samples were post-annealed in 5 different temperatures; as-deposited, $100^{\circ}C$, $200^{\circ}C$, $300^{\circ}C$, $400^{\circ}C$ and $500^{\circ}C$. Metal deposition was done on these samples by using Mo through E-beam evaporation. For analysis, three analysis methods were used; IV-characteristics by probe station, surface roughness by AFM, metal oxidation by FE-SEM. Experimental results say that contact resistance increased because of the metal oxidation on metal contact and rough surface of a-IGZO layer. we can suggest some of the possible solutions to overcome resistance effect for the improvement of TFT electrical performances.

• Journal of Food Hygiene and Safety
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• v.38 no.1
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• pp.31-36
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• 2023

This study was conducted to evaluate the efficacy of sodium hypochlorite in eliminating Escherichia coli strains from leafy green and stem vegetables, which are frequently sold at community service centers. A cocktail of non-pathogenic E. coli and enterohaemorrhagic E. coli (E. coli O157:H7) was used to artificially contaminate the vegetables (initial numbers of bacteria 7-8 log CFU/g). The contaminated vegetables were soaked in sodium hypochlorite for 5 min and then washed three times with running water. After the treatment, number of viable bacterial cells on the vegetables was estimated. Sodium hypochlorite treatment reduced the E. coli population by 1-2 log CFU/g on leafy green and stem vegetables, a significant reduction from the initial number. Further, sodium hypochlorite showed better antimicrobial efficacy for leaves with a larger surface area, less roughness, and softness. There was no significant difference in the antimicrobial effect between 100 and 200 mg/kg of sodium hypochlorite. Therefore, it is not necessary to increase sodium hypochlorite concentration than the level suggested in the school meal hygiene management guidelines. However, sodium hypochlorite treatment is not sufficient to achieve a safe level of microorganisms on leafy green and stem vegetables since they generally have a high abundance of microorganisms on their surface. Thus, an alternative cooking method for fresh leafy green and stem vegetables in summer should be developed to ensure they are safe for consumption.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.5
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• pp.240-246
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• 2002

$TiO_2$ films on soda-lime-silica glasses were prepared by spin coating-pyrolysis process using titanium naphthenate as a starting material. As-deposited films were pyrolyzed at $500^{\circ}C$ for 10 min in air and annealed at 500, 550 and $600^{\circ}C$ for 30 min in air. Crystallinity of the film was investigated by X-ray diffraction analysis. A field emission-scanning electron microscope and an atomic force microscope were used for characterizing the surface morphology and the surface roughness of the film. After annealing at 550 and $600^{\circ}C$, the X-ray diffraction patterns consist of only anatase peak. Films annealed at 500 and $550^{\circ}C$ exhibited flat surfaces. While with the increase in annealing temperature to $600^{\circ}C$, the $TiO_2$ film showed abnormal growth of three-dimensional needle-shaped grains. For all samples, high transmittance, above 90 % at 500 nm, was obtained at visible range. To investigate photocatalytic properties, IR absorbance associated with the C-H stretching vibrations of a thin solution-cast film of stearic acid under 365 nm (2.4 mW/$\textrm{cm}^2$) UV irradiation was estimated.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.2
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• pp.394-400
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• 2014

In this study, we fabricated ITZO thin films on glass substrates with various RF power from 30 to 60W and investigated the electrical, optical and structural properties. ITZO thin film deposited at 50W exhibited the largest figure of merit ($10.52{\times}10^{-3}{\Omega}^{-1}$) and then its resistivity and sheet resistance were $3.08{\times}10^{-4}{\Omega}-cm$ and $11.41{\Omega}/sq.$, respectively. As results of optical characterization, average transmittance of all ITZO thin films were over 80%. ITZO thin films had amorphous structure regardless of the RF power. The FESEM and AFM results showed that all ITZO thin films have a very smooth surface having no cracks and defects and the film deposited at 50W exhibit the smallest surface roughness of 0.254nm. We found that a amorphous ITZO thin film is a very promising material for replacing ITO in the next display device such as OLED.

• Textile Coloration and Finishing
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• v.30 no.2
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• pp.117-129
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• 2018

Cellulose has been widely applied into various medical fields including scaffolding, tissue engineering and tissue formation. In this study, we manufactured cellulose medical fiber from Styela clava tunics(SCT-CS) and analyzed the tensile strength, elongation at break, fluid uptake and surface morphology. And then, the biocompatibility and toxicity of SCT-CS were measured in Sprague-Dawley(SD) rats after the implantation for 30, 60 and 90 days. The level of tensile strength and fluid uptake were lower in SCT-CS than chromic catgut(CCG), while elongation at break level were maintained the higher in SCT-CS. Also, the roughness with pronounced surface patterns as a result of in vivo degradation was significantly greater in CCG than this of SCT-CS although these levels gradually appeared with time in both groups. After implantation for 90 days, SCT-CS and CCG was successfully implanted around muscle of thigh without any significant immune response. Furthermore, no significant alterations were measured in serum parameters and the specific pathological features induced by most toxic compounds for liver and kidney toxicity. Therefore, these results suggest that SCT-CS showing good biocompatibility and non-toxicity can be successfully prepared from cellulose powder of SCT as well as has the potential for use as a powerful biomaterial for medical sutures.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.6
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• pp.43-49
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• 2000

The TiN thin films were deposited by ALE(atomic layer epitaxy) on (100) silicon substrate. The TiN thin films were characterized by means of XRD, 4-point probe, AFM, AES and SEM. TEMAT(terakis(ethyl methy lamino)titanium) and $NH_3$ were injected into the reactor in sequence of TEMAT-$N_2-NH_3-N_2$ to ensure a saturated surface reaction. As a result, the depostion rate of the TiN film was controlled by self-limiting growth mechanism at temperature range form 150 to 220 $^{\circ}C$. Deposited TiN films, all of which show amorphous structure, had a fixed deposition rate of 4.5 ${\AA}$/cycle. The resistivity of 210 ~ 230 ${\mu}{\Omega}{\cdot}$cm and the surface r.m.s. roughness of 7.9 ~ 9.3 ${\AA}$ were measured. When TiN film of 2000 ${\AA}$ were deposited, a excellent step coverage were observed in a trench structure of 0.43${\mu}m$ contacts with 6:1 aspect ratio.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.3
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• pp.168-175
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• 2020

Purpose: The purpose is to test and evaluate the physical properties of commonly used temporary restoration materials and newly emerged materials. Materials and Methods: Four groups of polymer materials were evaluated: Polymethyl methacrylate (PMMA) 2 groups, Polyetheretherketone (PEEK), Polycarbonate. Four physical properties were tested: surface hardness, bending strength, abrasion resistance during wear, wear behavior. The 3-axis bending strength and Vickers hardness test were measured using a universal testing machines respectively. The microstructure was observed with a scanning electron microscope and weight comparison was evaluated after 100,000 chewing tests using a chewing simulator. Kruskal wallis test was performed to evaluate statistical significance. Results: The four groups showed the highest flexural strength and Vickers hardness of PEEK, followed by PC, PMMA-H, PMMA-T. Microstructure observation also showed the least surface roughness in the PEEK group, followed by PC, PMMA-H, PMMA-T. Conclusion: PC is considered to have sufficient mechanical properties that can be applied to the manufacture of temporary teeth. However, further studies, such as biocompatibility, are considered to be necessary for practical clinical applications.