• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권11호
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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.

• Bulletin of the Korean Chemical Society
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• 제33권8호
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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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• 제34권6호
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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.

• 대한치과교정학회지
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• 제5권1호
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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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• 제17권3호
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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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• 제31권1호
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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.

• 한국전기전자재료학회논문지
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• 제36권1호
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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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• 제16권3호
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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).

• Journal of Animal Science and Technology
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• 제51권5호
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• pp.369-378
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• 2009

본 시험은 여러 종류(호밀, RS; 볏짚, RSS; 소맥, WS; 트리티케일, TS; 귀리, OS; 청보리, BS)의 사일리지를 대상으로 단백질을 분획(fractionation)하고, in vitro 방법으로 buffer 추출 전과 추출 후의 사일리지를 배양하였을 때 반추위 미생물에 의한 발효성상, 가스발생량 및 분해율을 조사하고자 실시되었다. 사일리지의 가용성 물질은 boratephosphate 용액으로 추출하였으며, 반추위액과 인공 타액이 동일한 비율로 구성된 배양액을 혐기적인 조건에서 48시간동안 배양($39^{\circ}C$)하면서 발효 성상과 nylon bag을 이용한 사일리지의 in vitro 분해율을 조사하였다. 사일리지의 soluble protein (SP) 함량은 RSS에서 총 CP 함량 중 2.11%로 가장 낮았으며, RS와 BS 및 OS에서는 7% 이상의 높은 함량을 보였다. 또한 A fraction (NPN)은 RS에서 총 CP의 74.33%로 가장 높았으나 TS 및 RSS의 NPN 함량은 48% 정도로 비교적 낮았다. Buffer 불용성 단백질(IP) 중 B2 fraction은 RS, RSS 및 WS에서 총 CP의 7% 이상으로 비교적 높았던 반면 TS (1.45%)와 BS (2.13%)에서 매우 낮았다. 이와는 달리 $B_3$ fraction은 WS (4%)를 제외하고는 다른 사일리지에서 5.99~15.20%의 함량을 보였다. 체내 이용성이 매우 낮은 C fraction은 볏짚 사일리지(RSS)에서 27.07%로 다른 종류의 사일리지(1.40~9.93%)에 비하여 현저히 높은 수준이었다. 배양 12시간 까지는 추출 전에 비하여 추출 후의 사일리지 배양액에서 pH가 높았으나 (P<0.01~P<0.001) 48시간에는 오히려 추출 전의 사일리지 배양액의 pH가 낮았다(P<0.01). 배양액의 ammonia-N는 모든 사일리지에서 추출 전의 농도가 추출 후의 농도에 비하여 현저히(P<0.01~P<0.001) 높았으나 사일리지 종류에 의한 영향을 받지 않았다. 모든 사일리지에서 추출 후에 비하여 추출 전의 VFA 농도가 현저히 증가되었다(P<0.01~P<0.001). Acetate의 조성 비율은 buffer 추출 전에 비하여 배양 24시간까지 추출 후 모든 사일리지에서 높았던 (P<0.01~P<0.001) 반면 propionate와 butyrate 비율은 배양 24시간까지 추출 전에 더 높았다(P<0.001). 배양 12시간까지는 buffer 추출 전의 사일리지로부터 더 많은(P<0.01~P<0.001) 양의 gas가 발생되었지만 그 후로(24~48시간)는 오히려 buffer로 추출된 후의 사일리지에서 발생량이 더 많았다(P<0.01). 추출 후에 비하여 추출 전 사일리지의 DM과 CP 분해율이 현저히(P<0.001) 높았으나 NDF 분해율의 경우 오히려 추출 후의 사일리지에서 높았다(P<0.001). 그러나 각 사일리지에 대한 buffer 추출 전 후의 평균치에서는 사일리지 간에 차이가 없는 것으로 나타났다. 본 시험의 결과로 미루어 보아 사일리지로 인해 현저히 증가된 NPN 함량이 사일리지의 단백질 이용율을 크게 낮출 것으로 보이며, 단백질을 포함한 buffer 가용성 물질은 사일리지의 초기 발효를 크게 촉진할 수 있는 것으로 여겨진다.

• 한국지반공학회논문집
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• 제36권10호
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• pp.33-39
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• 2020

심층 처분 방식은 고준위폐기물을 처분하기 위한 가장 적합한 대안으로 고려되어지고 있다. 고준위폐기물은 공학적방벽시스템에 의해 지하 500~1,000m 깊이의 암반층에 처분된다. 공학적방벽시스템의 구성 요소로는 처분용기, 완충재, 뒷채움재 및 갭채움재가 있다. 이 중 벤토나이트 완충재는 지하수 유입으로부터 처분용기를 보호하고, 방사성 핵종 유출을 저지하는 역할을 하기에 심층 처분시스템에 있어 매우 중요하다고 할 수 있다. 초기에는 처분용기로부터 발생하는 고온의 열량으로 인해 완충재의 포화도는 감소하지만, 그 후 주변 암반으로부터 유입되는 지하수로 인해 완충재의 포화도는 증가한다. 이렇듯 완충재의 불포화 거동 특성은 공학적방벽의 전체 안전성을 좌우할 수 있는 중요한 입력자료이다. 국내의 경우 경주에서 생산되는 벤토나이트가 완충재의 주요 후보물질로 고려될 수 있는데 국내 벤토나이트 완충재의 온도를 고려한 불포화 거동 특성에 대한 연구는 매우 미진한 상황이다. 따라서 본 연구에서는 국내 압축 벤토나이트 완충재의 온도 증가에 따라 함수비가 일정한 조건에서의 함수특성곡선을 도출하였으며, 시험 값과 온도가 고려된 수정 van-Genuchten 모델 값과의 상대오차는 약 2%를 나타냈다.