• Title/Summary/Keyword: Buffer content

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Effect of Modifiers in Bioglass on the Glass Properties and the Formation of Apatite (Bioglass내의 수식체가 유리의 물성 및 아파타이트 형성에 미치는 영향)

  • 길철영;이호필
    • Journal of the Korean Ceramic Society
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    • v.29 no.8
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    • pp.623-629
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    • 1992
  • The possible use of bioglass as implant materials is due to its biocompatibility to human body. Even if many animal studies for the bioglasses have been performed, their compositional dependences of structures and physical properties are not fully understood. In the present work, physical property measurements such as density and thermal expansion coefficient were carried out for the bioglasses, with substitution of CaO for Na2O in bioglass composition (46.1%SiO2, 24.4%Na2O, 26.9%CaO, 2.6%P2O5:mol%). Hydroxyapatite formation on the glass surface was also examined after reacted in Tris-buffer solution. As CaO was substituted for Na2O, the bond strength between nonbridging oxygen and modifier became stronger to make glass structure rigid, and resulted in increase in density and decrease in thermal expansion coefficient. When the bioglasses were reacted in Tris-buffer solution, hydroxyapatite was formed on the bioglass surface for all prepared glasses in 2 hours, independently on CaO content, and the thickness of hydroxyapatite layer was decreased a little, while the thickness of SiO2 rich layer was decreased sharply with CaO content.

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Effects of Mo on the Passive Films Formed on Ni-(15, 30)Cr-5Mo Alloys in pH 8.5 Buffer Solution

  • Jang, Hee-Jin;Kwon, Hyuk-Sang
    • Journal of the Korean Electrochemical Society
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    • v.12 no.3
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    • pp.258-262
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    • 2009
  • The composition and semiconducting properties of the passive films formed on Ni- (15, 30)Cr-5Mo alloys in pH 8.5 buffer solution were examined. The depth concentration profile of passive films formed on Ni-(15, 30)Cr-5Mo in pH 8.5 buffer solution showed that Mo enhances the enrichment of Cr. The Mott-Schottky plot for the passive film on Ni-(15, 30)Cr- 5Mo closely resembled that for the film on Cr, whereas those for the less Cr-enriched film on Mo-free alloys showed similar behavior to that for the film on Ni. The acceptor density was reduced by increasing Cr content in Ni-(15, 30)Cr-(0, 5)Mo alloys, but addition of Mo considerably increased the acceptor density.

Development of an Efficient Media Streaming Relay Engine Using Buffer Control in Wireless Networks (미디어 버퍼 제어를 이용한 효율적인 무선 네트워크 스트리밍 중계 엔진 개발)

  • Je, Huigwang;Kwon, Dongwoo;Kim, Hyeonwoo;An, Donghyeok;Ju, Hongtaek
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.41 no.11
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    • pp.1580-1588
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    • 2016
  • Recently, as the proliferation of mobile smart devices, multimedia content sharing technologies between mobile smart devices have provided. For efficient content sharing in wireless networks, the hierarchical streaming network has been proposed. However, member devices in a network group experience frequent delay while playing multimedia content files because of excessive network resource occupation between a relay and member devices. In this paper, we propose an efficient multimedia streaming relay method using media buffer control to reduce network congestion during streaming from the relay device to the member devices. We also measured the number of buffering and buffering time of the proposed relay engine and compared them with the performance of the existing relay engine.

Fabrication and Characterization of $0.2\mu\textrm{m}$ InAlAs/InGaAs Metamorphic HEMT's with Inverse Step-Graded InAlAs Buffer on GaAs Substrate

  • Kim, Dae-Hyun;Kim, Sung-Won;Hong, Seong-Chul;Paek, Seung-Won;Lee, Jae-Hak;Chung, Ki-Woong;Seo, Kwang-Seok
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.1 no.2
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    • pp.111-115
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    • 2001
  • Metamorphic InAlAs/InGaAs HEMT are successfully demonstrated, exhibiting several advantages over conventional P-HEMT on GaAs and LM-HEMT on InP substrate. The strain-relaxed metamorphic structure is grown by MBE on the GaAs substrate with the inverse-step graded InAlAs metamorphic buffer. The device with 40% indium content shows the better characteristics than the device with 53% indium content. The fabricated metamorphic HEMT with $0.2\mu\textrm{m}$T-gate and 40% indium content shows the excellent DC and microwave characteristics of $V_{th}-0.65V,{\;}g_{m,max}=620{\;}mS/mm,{\;}f_T120GHZ{\;}and{\;}f_{max}=210GHZ$.

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Measurements of the Thermal Conductivity of Domestic Bentonite for Improving the Physical Performance of Buffer (완충재의 물리적 성능향상을 위한 국내 벤토나이트의 열전도도 측정실험)

  • Kim, Geon-Young;Kim, Seung-Soo;Choi, Jong-Won;Park, Seong-Wan;Bae, Dae-Seok
    • Journal of the Mineralogical Society of Korea
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    • v.19 no.2 s.48
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    • pp.89-98
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    • 2006
  • The thermal conductivities of bentonite blocks with various dry densities (1.6 and $1.8g/cm^3$), water contents (5, 9.4, 15, 20 wt%) and sand contents (0, 10, 20, 30 wt%) were measured in order to investigate the improvement in physical performance of buffer as an engineered barrier. The raw material was domestic bentonite from Oksan mine located in Gyeongju city. The increase in water content was most effective for improving the thermal conductivity. Especiallly, the bentonite blocks with more than 15 wt% of water content showed more than 1.0 W/mK values of thermal conductivity regardless of their dry densities and sand contents. Therefore, if the domestic Oksan bentonite is used as a buffer material, we can suggest that the manufacture of bentonite block having dry density of $1.6g/cm^3$, sand content of $10{\sim}30$ wt% and water content of 15 wt% will be most effective considering the easiness of a manufacturing of bentonite block and the efficiency of an increase in the thermal conductivity.

Thermal conductivity prediction model for compacted bentonites considering temperature variations

  • Yoon, Seok;Kim, Min-Jun;Park, Seunghun;Kim, Geon-Young
    • Nuclear Engineering and Technology
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    • v.53 no.10
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    • pp.3359-3366
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    • 2021
  • An engineered barrier system (EBS) for the deep geological disposal of high-level radioactive waste (HLW) is composed of a disposal canister, buffer material, gap-filling material, and backfill material. As the buffer fills the empty space between the disposal canisters and the near-field rock mass, heat energy from the canisters is released to the surrounding buffer material. It is vital that this heat energy is rapidly dissipated to the near-field rock mass, and thus the thermal conductivity of the buffer is a key parameter to consider when evaluating the safety of the overall disposal system. Therefore, to take into consideration the sizeable amount of heat being released from such canisters, this study investigated the thermal conductivity of Korean compacted bentonites and its variation within a temperature range of 25 ℃ to 80-90 ℃. As a result, thermal conductivity increased by 5-20% as the temperature increased. Furthermore, temperature had a greater effect under higher degrees of saturation and a lower impact under higher dry densities. This study also conducted a regression analysis with 147 sets of data to estimate the thermal conductivity of the compacted bentonite considering the initial dry density, water content, and variations in temperature. Furthermore, the Kriging method was adopted to establish an uncertainty metamodel of thermal conductivity to verify the regression model. The R2 value of the regression model was 0.925, and the regression model and metamodel showed similar results.

A Video Quality Control Scheme Based on Content Characteristics for Improving QoE in DASH Environments (DASH 환경에서 QoE 향상을 위한 콘텐츠 특성 기반의 비디오 품질 조절 기법)

  • Youn, Kimyung;Chung, Kwangsue
    • Journal of KIISE
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    • v.42 no.8
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    • pp.1039-1048
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    • 2015
  • Recently, the web-based adaptive streaming service, DASH (Dynamic Adaptive Streaming over HTTP), is receiving more attention. However, existing network-based and buffer-based video quality control schemes in DASH environments make oscillation of segment throughput, causing degradation of the quality of experience (QoE) with frequent quality changes and playback interruptions because these schemes do not consider the content characteristics. In this paper, we propose a C-DASH (Content Characteristics based Dynamic Adaptive Streaming over HTTP) scheme in order to improve the QoE in DASH environments. The C-DASH scheme performs seamless and smooth quality control based on the segment throughput, buffer status, and segment size of the content. Based on simulation results, it is confirmed that the C-DASH scheme can improve the QoE, when compared with the existing quality control schemes.

Evaluation for the Manufacturing Characteristics and Thermal Conductivity of Engineering Scale Bentonite-Sand Buffer Blocks (공학규모 벤토나이트-모래 완충재 블록의 성형특성 및 열전도도 평가)

  • Lee, Deuk-Hwan;Yoon, Seok;Kim, Jin-Seop;Lee, Gi-Jun;Kim, Ji-Won;Kim, Min-Jun
    • Journal of the Korean Geotechnical Society
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    • v.38 no.12
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    • pp.113-123
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    • 2022
  • The required density relationship according to the press pressure of the floating die method and the homogeneity of the density distribution in the buffer block was evaluated to analyze the manufacturing characteristics of engineering scale bentonite-sand buffer blocks. In addition, the thermal conductivity was measured and compared with that of the pure bentonite buffer block to evaluate the level of thermal conductivity performance improvement of the bentonite-sand buffer material. As a result, it was confirmed that the standard deviation of dry density decreased to 0.011 and showed a homogeneous density distribution under the condition of press pressure greater than 400 kg/cm2. Furthermore, as a result of the thermal conductivity test, the thermal conductivity of the buffer with optimum moisture content conditions was 1.345 and 1.261 W/(m·K) under the press pressure of 400 and 600 kg/cm2, respectively. It increased by 16.1% and 11.0% compared to the pure bentonite buffer material. Based on the results of this study, it is judged that it can be used as fundamental data for manufacturing a homogeneous bentonite-sand buffer block on an engineering scale.

QUANTITATIVE ANALYSES USING 4D MODELS - AN EXPLORATIVE STUDY

  • Rogier Jongeling;Jonghoon Kim;Claudio Mourgues;Martin Fischer;Thomas Olofsson
    • International conference on construction engineering and project management
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    • 2005.10a
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    • pp.830-835
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    • 2005
  • 4D models help construction planners to develop and evaluate construction plans. However, current analyses using 4D models are mainly visual and limit the quantitative comparison of construction alternatives. This paper explores the usefulness of extracting quantitative information from 4D models to support time-space analyses. We use two 4D models of an industry test case to illustrate how to analyze 4D content quantitatively (i.e., work space areas and distances between concurrent activities). This paper shows how these two types of 4D content can be extracted from 4D models to support 4D-based-analysis and novel presentation of construction planning information. We suggest further research to formalize the content of 4D models to enable comparative quantitative analyses of construction planning alternatives. Formalized 4D content will enable the development of reasoning mechanisms that automate 4D-model-based analyses and provide the information content for informative presentations of construction planning information.

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