• Journal of Korean Society for Atmospheric Environment
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• v.15 no.3
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• pp.327-333
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• 1999

Determination of chloride ion in concentrated NaOH solution by capillary electrophoresis has been studied. The analysis was performed by indirect UV absorption detection using chromate buffer at 254nm. The matrix effect of the sample has been observed so that the sensitivity in strong NaOH solutaion has decreased up to 10% of that in distilled water. The pH effect of the sample on the sensitivity of CE peaks has been investigated. The method for increasing the sensitivity have been investigated and the optimum pH and concentration of the buffer were 7.5 and 10mM, respectively. A cationic surfactant cetyltrimethylammonium bromide(CTAB), was added to a buffer solution in order to reverse the electroosmotic flow(EOF) in the capillary. This results in a short analysis time and better peak shapes. Using this optimum condition, the determination of chloride ion in real environmental sample has been performed, which is captured in strong NaOH absorbent prepared for absorbing gas from chimney. The standard addition method has been applied for the quantitative analysis, and it was obtained the good reproducibility.

• Journal of the Korean Chemical Society
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• v.57 no.5
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• pp.533-539
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• 2013

The electrochemical corrosion and passivation of Ni rotating disk electrod in borate buffer solution was studied with potentiodynamic and electrochemical impedance spectroscopy. The mechanisms of both the active dissolution and passivation of nickel and the hydrogen evolution in reduction reaction were hypothetically established while utilizing the Tafel slope, impedance data, the rotation speed of Ni-RDE and the pH dependence of corrosion potential and current. Based on the EIS data, an equivalent circuit was suggested. In addition, carefully measured were the electrochemical parameters for specific anodic dissolution regions. It can be concluded from the data collected that the $Ni(OH)_2$ oxide film, which is primarily formed by passivation, is converted to NiO by dehydration under the influence of an electrical field.

• Journal of Pharmaceutical Investigation
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• v.22 no.3
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• pp.211-217
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• 1992

Stabilization of liposomes against degradation by bile salts has been investigated in order to develop a liposomal model system for oral drug delivery. Two polysaccharides, amylopectin (AP) and chitin (CT), were employed to coat both empty liposomes and bromthymol blue (BTB)-encapsulated liposomes by adsorption-coating techniques. Turbidity changes and BTB-release characteristics in pH 5.6 buffer solutions with or without bile salts, sodium cholate and sodium glycocholate, were observed to compare the differences between uncoated liposomes and polysaccharide-coated liposomes. Initial turbidities of both uncoated and polysaccharide-coated liposomes in buffer solution were kept constant within 3% range during 4 hours of experiments. But they were decreased in a different manner in bile salts-containing buffer solutions, showing 10% or less decrease for polysaccharide-coated liposomes and 25% or more decrease for uncoated liposomes. BTB release from uncoated liposomes has been greatly increased upto 90% after 4 hours in bile salts-containing buffer solution, which is a clue for breakdown of liposomal vesicles. However, polysaccharide-coated liposomes showed the controlled-release pattern which is proportional to square-root of time, followed by around 50% release for the same time period. Consequently, it is possible to conclude that these polysaccharide-coated liposomes might be an available system for oral delivery of a drug which is unstable in gut environment.

• Journal of the Korean Chemical Society
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• v.16 no.3
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• pp.149-156
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• 1972

The responsive characteristics of hydrogen-responsive glass electrode in various buffer solutions of methanol, N,N-dimethylformamide and acetonitrile were examined. The potentials were attained more rapidly with an electrode stored in the same solvent medium than that stored in water before use. However, the time to be required for a stable potential increased with the basicity of buffer solution, and it was not provide a constant potential in the strong basic solution of these solvent. Even in acidic solution, the potential was varied according to the past usage of the electrode.

• Journal of the Korean Chemical Society
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• v.6 no.1
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• pp.29-31
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• 1962

Paper electrophoresis of aluminium ion was studied using a closed horizontal type apparatus. The optimal conditions of voltage, pH of electrolytic supporting solution and migration time were determined for the electrophoretic migration of the ion on the paper strip saturated by Michaelis buffer solution. The mobility of the ion and the isoelectric point of $Al(NO_3)_3$ solution were $(1.004{\pm}0.0020){\times}10^{-4}\;cm^2\;sec^{-1}\;volt^{-1}$ at pH = 2.38 and pH = 3.23 respectively.

• Journal of KIISE
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• v.43 no.3
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• pp.327-335
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• 2016

In this paper, we propose a buffer management scheme suitable for interactive multimedia services. We consider a typical delay optimization environment so that receiver buffer lengths vary according to the round trip time estimation. In this environment, we propose an optimization technique for minimizing the loss of information that may occur when a reduced buffer length forces I/P/B frames in the buffer to drop. We modeled our problem as a Knapsack Problem for which we used dynamic programing in order to find an approximate solution. The proposed technique is compared with the existing buffer management techniques. Through simulation studies, we found that our approach could increase PSNR, which is important to video quality.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.1
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• pp.37-41
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• 2001

HPLC separation of ionic samples tends to be more complicated and difficult to understand than that of non-ionic compounds. On the other hand, band spacing is much more easily manipulated for ionic than for neutral samples. Ion-suppression RP-HPLC method was used with organic modifier and aqueous buffer solution. In this work, five mononucleotides of cytidine-5-monophosphate (5-CMP) disodium salt, uridine-5-monophosphate disodium salt (5-UMP), guanosine-5-monophosphate disodium salt (5-GMP), inosine-5-monophosphate disodium salt (5-IMP), and adenosine-5-monophosphate disodium salt (5-AMP) were examined. Acetic acid and sodium phosphate were used as buffers, and methanol as an organic modifier. A new relationship between the retention factor and the buffer concentration at a fixed modifier content (5% of methanol) could be expressed by following: K = (k(sub)-1 + k(sub)0 (k(sub)B/k(sub)S)/(1 + (k(sub)B/k(sub)S) C(sub)B(sup)a), where C(sub)B was the concentration of buffer. Using this relationship, the calculated values closely matched the experimental data. The derived relationship showed that as the buffer concentration increased, the retention factor approached a certain value, and this was buffer dependent.

• Restorative Dentistry and Endodontics
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• v.18 no.2
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• pp.277-290
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• 1993

Dental caries is considered to be caused by demineralization by organic acid produced by microorganism. But the formation of subsurface lesion in initial caries make it diffcult to explain by simple demineralization. This study is carried out on the basis of thermodynamic concept proposed by Margolis and Moreno. The purpose of this study is to evaluate the effects of acid concentration and pH of lactate buffer system on the artificial caries lesion progress. 160 teeth without any crack, defect or opaque enamel were used and coated with nail varnish except the window ($2{\times}3$ mm). Under the constant degree of saturation(D.S.). The teeth were divided into 8 groups according to acid concentration(10mM, 25mM, 50mM, 100mM) and pH(4.3, 5.0, 6.0). Each group was immersed in buffer solution for 3, 6, 9, 18 days under controlled temperature($25^{\circ}C$). After cutting through the window and grinding, the specimens, 100-150 um in thickness, were imbibed in water or air and examined using polarilizing microscope. The depth of the surface and subsurface surface lesion were measured. 1. In the constant pH and D. S. value, the subsurface lesion progresses more rapidly as the concentration of lactic acid increases. (0.01, 0.025, 0.05, 0.1) 2. In the constant acid concentration and DS value, the subsurface lesion progresses more slowly as the pH increases. (4.3, 5.0, 5.5, 6.0) 3. The width of surface lesion seems to be constant independant of pH and acid concentration.

• YAKHAK HOEJI
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• v.30 no.5
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• pp.228-231
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• 1986

The effect of temperature and pH on the degrdation of minoxidil in the aqueous solution was investigated and the stability of pharmaceutical preparation for solution was also studied. The degradation of minoxidil in the aqueous solution was first order type reaction and the rate constant at $20^{\circ}C$ in pH 7.0 phosphate buffer solution was 9.464${\times]10^{-3} day^{-1}$ and calculated activation energy was 11.7 kcal/mol. The degradation of minoxidil was acid-base catalytic reaction and the most stable range of pH was about 5.0. The liquid pharmaceutical preparation was very stable in 3 months.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.10
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• pp.95-102
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• 2003

The buffering is a promising solution to resolve the contention problem in optical network. we study the packet loss probability and the dimensioning of optical buffer using a Fiber Delay Line for variable length packet. In this paper, we study the relation between the granularity and the loss of FDL buffer in Single-Stage FDL buffer and propose the Single-Bundle Multi-Stage FDL buffer. The Multi-Stage FDL buffer is too early yet to apply to the current backbone network, considering the current technology in view of costs. but we assume that the above restriction will be resolved in these days. The appropriate number of delay and pass line for a dimensioning is based on a amount of occupied time by packets. Once more another multi-stage FDL buffer is proposed, Split-Bundle multi-stage FDL buffer. The Split-Bundle ms-FDL buffer is more feasible for a FDL buffer structure, considering not only a size of switching matrix but also a bulk of switching element. its feasibility will be demonstrated from a loss probability.