• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.1
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• pp.308-324
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• 2018

HTTP adaptive streaming (HAS) is a promising technology for delivering video content over the Internet. HAS-based video streaming solutions rely on bandwidth estimation to select the appropriate video bitrate. Video streaming solutions that consider network conditions provide users with seamless video playback. However, when multiple clients compete for a common bottleneck link, conventional bandwidth estimation schemes that consider only one client overestimate the network bandwidth due to the ON-OFF traffic pattern. The bandwidth overestimation can cause Quality of Experience (QoE) degradation, such as unnecessary changes in video quality, and unfairness of video quality. In this paper, we propose a client-side bandwidth estimation scheme to obtain a better QoE of HAS in the multiple-client environment. The proposed scheme differentiates the client buffer status according to the buffer occupancy, and then estimates the available network bandwidth based on the buffer status and segment throughput. We evaluate the performance of HAS implemented in the ns-3 network simulator. Simulation results show that compared with the conventional schemes, the proposed scheme can enhance the QoE.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.11
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• pp.4585-4603
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• 2015

Video streaming services make up a large proportion of Internet traffic on both fixed and mobile access throughout the world. Adaptive streaming allows for dynamical adaptation of the bitrate with varying network conditions, to guarantee the best user experience. Adaptive bitrate algorithms face a significant challenge in correctly estimating the throughput as it varies widely over time. In this paper, we first evaluate the throughput estimation techniques and show that the method that we have used offers stable response to throughput fluctuations while maintaining a stable playback buffer. Then, we propose an adaptive bitrate scheme that intelligently selects the video bitrates based on the estimated throughput and buffer occupancy. We show that the proposed scheme improves viewing experience by achieving a high video rate without taking unnecessary risks and by minimizing the frequency of changes in the video quality. Furthermore, we show that it offers a stable response to short-term fluctuations and responds swiftly to large fluctuations. We evaluate our algorithm for both constant bitrate (CBR) and variable bitrate (VBR) video content by taking into account the segment sizes and show that it significantly improves the quality of video streaming.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.22 no.1
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• pp.9-16
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• 2024

The bentonite buffer material is a crucial component in an engineered barrier system used for the disposal of high-level radioactive waste. Because a large amount of heat from the disposal canister is released into the bentonite buffer material, the thermal conductivity of the bentonite buffer is a crucial parameter that determines the design temperature. At the Korea Atomic Energy Research Institute (KAERI), a new standard bentonite (Bentonil-WRK) has been used since 2022 because Gyeongju (KJ) bentonite is no longer produced. However, the currently available data are insufficient, making it essential to investigate both the basic and complex properties of Bentonil-WRK. Thus, this study evaluated its geotechnical and thermal properties and developed a thermal conductivity empirical model that considers its dry density, water content, and temperature variations from room temperature to 90℃. The coefficient of determination (R²) for the model was found to be 0.986. The thermal conductivity values of Bentonil-WRK were 1-10% lower than those of KJ bentonite and 10-40% higher than those of MX-80 bentonites, which were attributable to mineral-composition differences. The thermal conductivity of Bentonil-WRK ranged between 0.504 and 1.149 W·(m^-1·K^-1), while the specific heat capacity varied from 0.826 to 1.138 (kJ·(kg^-1·K^-1)).

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2651-2656
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• 2012

Sulfonated cellulose tris(3,5-dimethylphenylcarbamate) (SCDMPC)-coated zirconia monolith (ZM) was used as the chiral stationary phase in capillary electrochromatography for separation of enantiomers of ten chiral compounds in acetonitrile (ACN)-phosphate buffer mixtures as the eluent. Influences of the ACN content, buffer concentration and pH on chiral separation have been investigated. Separation data on SCDMPC-ZM have been compared with those on CDMPC-ZM. Resolution factors were better on SCDMPC-ZM than CDMPC-ZM while retention factors were in general shorter on the former than the latter. Best chiral resolutions on SCDMPC-ZM were obtained with the eluent of 50% ACN containing 50 mM phosphate at pH around 4.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1809-1813
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• 2013

Sulfated ${\beta}$-cyclodextrin (SCD)-coated zirconia monolith was used as the chiral stationary phase in capillary electrochromatography for enantiomeric separation of basic chiral compounds. SCD adsorbed on the zirconia surface provided a stable chiral stationary phase in reversed-phase eluents. Retention, chiral selectivity and resolution of a set of six basic chiral compounds were measured in eluents of varying pH, composition of methanol and buffer. Optimum mobile phase condition for the separation of the compounds was found to be methanol content of 30%, buffer concentration of 30 mM and pH of 4.0.

• The korean journal of orthodontics
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• v.5 no.1
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• pp.21-24
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• 1975

The purpose of this study was to investigate the effect of sinc phosphate cement on the enamel surface of extracted teeth. The tooth was placed in a test tube, which was subjected to 5ml of 0.2M acetate buffer at pH 4 by 'window technique.' The calcium content of the acetate buffer was determined by the Perkin-Elmer Model 303 Atomic Absorption Spectrophotometer. The obtained results were summarized in the following. 1. The solubility of enamel is $0.92mg/cm^2$. ml in control group. 2. The solubility of enamel is increased by treating these with zinc phosphate cements. 3. The solubility of enamel is $0.69mg/cm^2$. ml by treating with Lee Smith cement. 4. The solubility of enamel is $0.30mg/cm^2$. ml by treating with G-C's cement.

• Journal of Pharmaceutical Investigation
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• v.17 no.3
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• pp.127-133
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• 1987

Dissolution characteristics and urinary excreted amount of commercially available three brands of sulfisoxazole tablets were investigated in order to elucidate the in vitro-in vivo correlations and relative bioavailability in humans. All the tablets tested met the K.P. IV and the USP XXI specifications for tablet weight variation, content uniformity, disintegration and dissolution. The disintegration and dissolution rate constants of sulfisoxazole tablets in pH 2.0 HCl-KCl buffer were reduced more significantly (p<0.05) than those in diluted HCl $(1{\rightarrow}12.5)$ and pH 6.5 phosphate buffer. It seemed to be attributed to the pH dependent solubility of sulfisoxazole. We could see that the relative bioavailability of brand B to sulfisoxazole powder was about 90% and that its value was higher than those of other two brands from the urinary excretion data obtained from eight healthy male volunteers by means of Latin square cross over design. No useful correlation was observed between the in vitro and in vivo studies in this experiment.

• Bulletin of the Korean Chemical Society
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• v.31 no.1
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• pp.82-86
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• 2010

Quinine (QN) is a weak anion-exchange type chiral selector and QN-based silica stationary phases have been widely used for enantioseparation of acidic chiral analytes in HPLC and recently in CEC. In this work we report enantioseparation of non-acidic chiral analytes on a quinine carbamate-immobilized zirconia (QNZ) in reversed-phase (RP) CEC. Influences of pH, composition of the buffer, acetonitrile content and the applied voltage on enantioseparation were examined. Enantiomers of the analytes investigated are well separated in acetonitrile/phosphate buffer mobile phases. Separation data on QNZ were compared to those on QN-bonded silica (QNS). Retention was longer but better enantioselectivity and resolution were obtained on QNZ than QNS.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.1
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• pp.36-41
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• 2023

We investigated the properties of vanadium oxide (VOx) buffer layers deposited by a dual RF magnetron sputtering method under various target powers for inverted organic solar cells (IOSCs). Sputter fabricatged VOx thin films exhibited higher crystallinity with the increase of target power, resulting in a uniform and large grain size. The electrical properties of VOx films are improved with the increase of target power because of the increase of V content. In the results, the performance of IOSCs critically depended on the target power during the film growth because the crystalllinity of the VOx film affects the carrier mobility of the VOx film.

• Food Science and Biotechnology
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• v.16 no.3
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• pp.444-450
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• 2007

The antioxidant activity and isoflavone content of chokong, Rhynchosia nolubilis seeds pickled in vinegar at $4^{\circ}C$ for 2 weeks, were investigated. The polyphenol content and 2,2-diphenyl-1-pycrylhydrazyl (DPPH) radical-scavenging capacity were lower in chokong than in raw seeds. Based on isoflavone analysis, the aglycone (daidzein and genistein) content was high in chokong while the content of the corresponding glucosides (daidzin and genistin) was similar to that in raw seeds. Thermal processing, in which seeds were heated in vinegar at $121^{\circ}C$ for 20 min, reduced the polyphenol content but did not affect the DPPH radical-scavenging capacity compared to the pickling process. The heated seeds had a 2.6 to 2.7 times higher glucoside content and 51 to 55% lower aglycone content than chokong, depending on the kind of vinegar used. During pickling and thermal processing, vinegars were more effective at eluting antioxidants and isoflavones from seeds than other solutions such as acetic acid, citric acid and HCl solutions, distilled water, and phosphate buffer (pH 7.0).