• Korean Journal of Human Ecology
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• v.21 no.4
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• pp.791-803
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• 2012

This study intends to identify applicability of natural dye extracted from Aplysia kurodai, aiming to standardization of Aplysia kurodai natural dyeing through scientific validation by analyzing characteristics of pigment elements to review dyeability, colorfastness and antibacterial activity. Such material as silk fabrics that is animal fiber were used for this purpose, and derived following summarized results. UV/VIS spectrum analysis on the pigment of Aplysia kurodai that was extracted from purple gland showed that maximum absorbtion was near 540 nm. The silk fabric optimal dyeing can be achieved at a temperature of $55^{\circ}C$ with a colorant concentration of 5%. Dyed at $55^{\circ}C$ with interval of 10~90 minutes for identifying dye uptake over time to observed slow increase of dye uptake over time, and equilibrium occurred at 50 minutes. For dye uptake according to pH, while dye uptake was superior in acidity, it decreased rapidly in a base after pH 7. For color changes according to pH variation, it was reddish purple in acidity and was purplish red in a base. For color changes according to mordanting method, more clear color change had been obtained when process with aluminium pre-mordanting than non-mordanting and post-mordanting. The colorfastness to light, perspiration and washing was 1, 4~5, and 3~4 ratings respectively. The silk fabric dyed with Aplysia kurodai demonstrated excellent antimicrobial activity to Staphylococcus aureus and Klebsiella pneumoniae. The Aplysia kurodai can be used as a new colorant for the natural dyeing of silk.

• YAKHAK HOEJI
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• v.34 no.6
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• pp.415-421
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• 1990

The effects of temperature, pH, light and concentration on the degradation of trimebutine maleate in aqueous solution were investigated on the basis of accelerated stability analysis, and the stabilization of the solution was attempted by addition of several additives. The decomposition of trimebutine maleate in solution followed first-order reaction the was not only accelerated by temperature elevation but also the lower the concentratin the more speeded up the reaction. The decomposition mechanism of trimebtine could be confirmed by hydrolysis of ester bond in the structure. It was assumed trimebutine maleate is so photosensitive that the solution of the drug underwent accelerated decomposition under UV rays. What is more, the degradation of trimebutine solution was supposed to catalyzed by specific acid-base catalysis considered the pH dependence for the hydrolysis of ester, and the solution was most stable over the range of pH 2-2.8 in solution. The additives, citric acid, asparitc acid and glutamic acid, inhibited considerably the decomposition of the drug solution, and these additives might be used as stabilizers in trimebutine maleate solution.

• Korean Chemical Engineering Research
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• v.51 no.4
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• pp.426-431
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• 2013

Nanosized $TiO_2$ particles were prepared from titanium (IV) sulfate solution using base solutions at low reaction temperature ($95^{\circ}C$) and atmospheric pressure by hydrothermal precipitation method without calcination. The effects of preparation conditions, such as kind of base solutions (NaOH, $NH_4OH$, Monoethanolamine, Diethanolamine, Triethanolamine) and surfactants (CTAB, Span 20, SDBS), concentration of surfactants, temperature and pH, on the physical properties of $TiO_2$ particles have been investigated by XRD, SEM and Zeta-potential meter. Absorption area was also investigated by DRS in order to confirm the photocatalytic activity of the nanosized $TiO_2$ particles. It was turned out that, among base solutions, NaOH provides the smallest $TiO_2$ particles with excellent crystallinity. And cationic surfactant (CTAB) prepared smaller $TiO_2$ particles than any other surfactants. When CTAB is added in the concentration ratio of $Ti(SO_4)_2$:CTAB=10:1, $TiO_2$ particles with particle diameter of 5.8 nm were prepared. This is approximately 1/10 of that prepared without CTAB.

• The Journal of Advanced Prosthodontics
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• v.10 no.2
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• pp.113-121
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• 2018

PURPOSE. The aim of this preliminary study was to investigate, for the first time, the effects of addition of titania nanotubes ($n-TiO_2$) to poly methyl methacrylate (PMMA) on mechanical properties of PMMA denture base. MATERIALS AND METHODS. $TiO_2$ nanotubes were prepared using alkaline hydrothermal process. Obtained nanotubes were assessed using FESEM-EDX, XRD, and FT-IR. For 3 experiments of this study (fracture toughness, three-point bending flexural strength, and Vickers microhardness), 135 specimens were prepared according to ISO 20795-1:2013 (n of each experiment=45). For each experiment, PMMA was mixed with 0% (control), 2.5 wt%, and 5 wt% nanotubes. From each $TiO_2$:PMMA ratio, 15 specimens were fabricated for each experiment. Effects of $n-TiO_2$ addition on 3 mechanical properties were assessed using Pearson, ANOVA, and Tukey tests. RESULTS. SEM images of $n-TiO_2$ exhibited the presence of elongated tubular structures. The XRD pattern of synthesized $n-TiO_2$ represented the anatase crystal phase of $TiO_2$. Moderate to very strong significant positive correlations were observed between the concentration of $n-TiO_2$ and each of the 3 physicomechanical properties of PMMA (Pearson's P value ${\leq}.001$, correlation coefficient ranging between 0.5 and 0.9). Flexural strength and hardness values of specimens modified with both 2.5 and 5 wt% $n-TiO_2$ were significantly higher than those of control ($P{\leq}.001$). Fracture toughness of samples reinforced with 5 wt% $n-TiO_2$ (but not those of 2.5% $n-TiO_2$) was higher than control (P=.002). CONCLUSION. Titania nanotubes were successfully introduced for the first time as a means of enhancing the hardness, flexural strength, and fracture toughness of denture base PMMA.

• Corrosion Science and Technology
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• v.10 no.4
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• pp.109-117
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• 2011

The Korean Peninsula is located in the middle latitude of the northern hemisphere and has a clear 4-seasons and shows the typical temperate climate. Because of seasonal winds, it is cold and dry by a northwestern wind in the winter and it is hot and humid by a southeast wind in the summer. Also, temperature difference between the winter and the summer is large and it shows a rainy season from June to July but recently this regular trend may be greatly changed by an unusual weather phenomena. Since the Peninsula is east high west low type, the climate is complicated too. Because these geographical and climate characteristics can affect the properties of corrosion of metals and alloys, a systematic research on atmospheric corrosion in the Peninsula is required to understand and control the corrosion behavior of the industrial facilities. This paper analyzed the atmospheric corrosion factors for several environments in the Korean Peninsula and categorized the corrosivity of atmospheric corrosion of metals and alloys on the base of the related ISO standards. Annual pH values of rain showed the range of 4.5~5.5 in Korean Peninsula from 1999 to 2009 and coastal area showed relatively the low pH's rain. Annual $SO_2$ concentrations is reduced with time and its concentrations of every major cities were below the air quality standard, but $NO_2$concentration revealed a steady state and its concentration of Seoul has been over air quality standard. In 2007, $SO_2$classes of each sites were in $P_0{\sim}P_1$, and chloride classes were in $S_0{\sim}S_1$, and TOW classes were in ${\tau}_3{\sim}{\tau}_4$.That is, $SO_2$ and chloride classes were low but TOW class was high in Korean Peninsula. On the base of these environmental classes, corrosivity of carbon steel, zinc, copper, aluminium can be calculated that carbon steel was in C2-C3 classes and it was classified as low-medium, and zinc, copper, and aluminium showed C3 class and it was classified as medium.

• Journal of Mechanical Science and Technology
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• v.17 no.9
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• pp.1276-1286
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• 2003

The performance of porous bearing under different lubricants and lubricating conditions was experimentally investigated in this study. In order to carry out the experiments, a new test rig was designed to determine the tribological properties of based sintered bronze journal bearings that were manufactured by powder metallurgy (P/M) techniques. To determine the effects of lubricating conditions with and without oil supplement (OS) on the tribological characteristics of these bearings under static loading and periodic loadings, some experiments were carried out using different lubricants. In the tests, pure base oil (SAE 20W50), two fully formulated commercial engine oils (SAE20W50) and lubricating oils with commercial additive concentration ratio of 3％ were used. The worn surfaces of test bearings were examined using optical microscopy. Experimental results showed that the change in friction coefficient was more stable and in smaller magnitude under static loading than that of periodic loading. In addition, the friction coefficient and the wear rate conducted with base oil resulted in higher values than those of fully formulated oils with and without OS lubricating conditions. The experimental results obtained in this study indicated that the correct selection of lubricant and suitable running conditions were very important on the tribological characteristics of porous bearings.

• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.629-633
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• 2004

A new PVC membrane electrode for $UO_2^{2+}$ ion based on 2,2'-[1,2-ethanediyl bis (nitriloethylidene)]bis(1-naphthalene) as a suitable ionophore was prepared. The electrode exhibites a Nernstian response for $UO_2^{2+}$ ion over a wide concentration range ($1.0{\times}10^{-1}-1.0{\times}10^{-7}$M) with a slope of 28.5 ${\pm}$ 0.8 mV/decade. The limit of detection is $7.0{\times}10^{-8}$M. The electrode has a response time of < 20 s and a useful working pH range of 3-4. The proposed membrane sensor shows good discriminating abilities towards $UO_2^{2+}$ ion with regard to several alkali, alkaline earth transition and heavy metal ions. It was successfully used to the recovery of uranyl ion from, tap water and, as an indicator electrode, in potentiometric titration of $UO_2^{2+}$ ion with Piroxycam.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.45-53
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• 2016

This study examined pruritus to provide the data based on burn patient pruritus. A self-report questionnaire survey was conducted among ninety five burn survivors, who were over 18 years of age with admission periods longer than two weeks. The results indicated that the average burn range was $18.95{\pm}17.10%$, severity was $48.83{\pm}23.96$, and distress was $46.42{\pm}25.80$. A significant difference in pruritus consequences was observed according to frequency. The patients consistently experienced pruritus, even if it happened less often, difficulty in falling asleep (F=4.817, p=.004), poor mood (F= 5.955, p=.015)), and loss of concentration (F=6.483, p<.000). A significant difference in the pruritus consequences according to duration was observed, lasting for 30 minutes for all groups, more than the population and less than 30 minutes, difficulty in falling asleep (F=7.452, p<.000), poor mood (F=3.655, p<.015), and loss of concentration (F=12.564, p<.000). The frequency, duration (r=.29, p=.004), severity (r=.45, p<.000), distress (r=.44, p<.000), and consequences of pruritus in burn patients (r=.29, p=.004) showed a positive correlation. The results of this study could be used as a base material for the care of burn patients experiencing pruritus.

• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1439-1444
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• 2006

A $Cu^{2+}$ ion-selective membrane microelectrode has been fabricated from poly vinyl chloride (PVC) matrix membrane containing a new symmetrical hexadentate Schiff,s base 2-{1-(E)-2-((Z)-2-{(E)-2-[(Z)-1-(2-hydroxyphenyl)ethylidene]hydrazono}-1-methylpropylidene)hydrazono]ethyl}phenol (HDNOS) as a neutral carrier, Potassium tetrakis(4-chlorophenyl) borate (KTpClPB) as an anionic excluder and o-nitrophenyloctyl ether (NPOE) as a plasticizing solvent mediator. The microelectrode displays linear potential response in the concentration range of $1.0\;{\times}\;10^{-5}-1.0\;{\times}\;10^{-11}$ M of $Cu^{2+}$. The microelectrode exhibits a nice Nernstian slope of 25.9 ${\pm}$ 0.3 mV $decade^{-1}$ in the pH range of 3.1-8.1. The sensor has a relatively short response time in whole concentration ranges ($\sim$5 s). The detection limit of proposed sensor is $5.0\;{\times}\;10^{-12}$ M (320 pg/L), and it can be used over a period of eight weeks. The practical utility of the sensor has been demonstrated by using it as an indicator electrode in the potentiometric titration of $Cu^{2+}$ with EDTA. The proposed membrane electrode was used for the direct determining of $Cu^{2+}$ content in black and red pepper, and in waste water samples.

• Archives of Pharmacal Research
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• v.18 no.4
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• pp.219-223
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• 1995

Rectal absorption of opeprazole, a proton pump inhibitor, from suppositories was studied in rabbits. The suppositories were prepared by the conventional melting method with two types of bases, water-soluble polyethylene glycol (PEG) 4000 and oil-soluble Witepsol H15 bases, and administered intractally (ir) to rabbits at a dose of 10 mg omeprazole/kg. The plasma omeprazole concentration-time profiles of the two suppositories were compared with those following intravenous 9iv) administration of the same dose. There were no significant differences between the two suppositories in bioabailabilities and peak plasma concentrations $(C_{max})$. Bioavaiabilities and $C_{max}$ of PEG- and Witpsol suppositories were 30.3 and 33.9%, and 7.0 and $5.6\mug/ml$, resepectively. However, PEG suppository showed significantly (p<0.05) shorter time to reach peak plasma concentration $(T_{max})$ mean absorption time (MAT) and mean residence time in the plasma (MRT) than Witepsol suppository. The $T_{max}$ MRT nad MAT were 25.0, 83.0 and 38.5 min for PEG syppository, but were 90.0, 122.5 and 78.0 min for Wiepsol supposiotory, respectively. These differences between thw two suppositories could be explanined by the difference in the in vitro dissolution rates between the suppositories. The dissolution of omeprazole form PEG suppository was reportedly much faster than that from Witepsol suppository. It suggests that plasma profiles of omeprazole, especially $C_{max}$ MAT and MRT, could be controlled by modifying the in vitro dissolution rate of the drug from the suppositories. Above results suggest that rectal suppository is worth developing as an alternative dosage form of omeprazole to the conventional oral preparations which need sophisticated treatments, such as enterix coating, to prevent acid degradation of the drug in the stomach fluid.