• Title/Summary/Keyword: mixing volume

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Preparation and Characterization of Porous Sintered Body Made from Coal Bottom Ash and Dredged soil (석탄(石炭) 바닥재와 준설토(浚渫土)를 이용한 다공성(多孔性) 소결체(燒結體)의 제조 및 특성 평가)

  • Kim, Kang-Duk;Kang, Seung-Gu
    • Resources Recycling
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    • v.19 no.1
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    • pp.33-39
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    • 2010
  • The spheric sintered body with $6{\pm}2mm$ diameter was manufactured in a rotary kiln at $1125^{\circ}C$/15 min using green body formed by pelletizing the batch powder composing of coal bottom ash produced from power plant and dredged soil by 70:30, wt%. And the physical properties of sintered body (BD) were analyzed to confirm the possibility for applying to an absorbent to restore a contaminated soil. The sintered body had a giant pore above 100 ${\mu}m$ and a fine pore below 10 ${\mu}m$, and bulk density was 1.4. Also its specific surface area, porosity and void proportion were $12.0m^2/g$, 30.1% and 38.2% respectively. The crushed body (BD-C), produced by crushing a BD specimen into an irregular shape with a aspect ratio of about 2, was similar to BD specimen at bulk density and pore size distribution. But it had superior values of specific surface area, porosity and void proportion compared with BD specimen owing to a decreased apparent volume due to conversion of closed pore existed at interior of BD to open pore during a crushing process. The IEP of sintered body occurred at about pH=5, so the optimum pH condition of reacting aqueous solution could be known before bonding a microbe to the sintered body. Hence, the optimum void proportion and porosity of an absorbent can be obtained by appropriate mixing a BD with BD-C from the base data calculated in this study.

Comparison of Volume of Fluid (VOF) type Interface Capturing Schemes using Eulerian Grid System (오일러 격자체계에서 유체율 함수에 기초한 경계면 추적기법의 비교)

  • Kim, Do-Sam;Kim, Tag-Gyeom;Shin, Bum-Shick;Lee, Kwang-Ho
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.32 no.1
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    • pp.1-10
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    • 2020
  • The application of multiphase flows is increasingly being applied to analyze phenomena such as single phase flows where the fluid boundary changes continuously over time or the problem of mixing a liquid phase and a gas phase. In particular, multiphase flow models that take into account incompressible Newtonian fluids for liquid and gas are often applied to solve the problems of the free water surface such as wave fields. In general, multi-phase flow models require time-based the surface tracking of each fluid's phase boundary, which determines the accuracy of the final calculation of the model. This study evaluates the advection performance of representative VOF-type boundary tracking techniques applied to various CFD numerical codes. The effectiveness of the FCT method to control the numerical flux to minimize the numerical diffusion in the conventional VOF-type boundary tracking method and advection calculation was mainly evaluated. In addition, the possibility of tracking performance of free surface using CIP method (Yabe and Aoki, 1991) was also investigated. Numerical results show that the FCT-VOF method introducing an anti-diffusive flux to precent excessive diffusion is superior to other methods under the confined conditions in this study. The results from this study are expected to be used as an important basic data in selecting free surface tracking techniques applied to various numerical codes.

Precipitation-Filtering Method for Reuse of Uranium Electrokinetic Leachate (우라늄 오염 동전기 침출액의 재이용을 위한 침전-여과 방법)

  • Kim, Gye-Nam;Shon, Dong-Bin;Park, Hye-Min;Kim, Ki-Hong;Lee, Ki-Won;Moon, Jeik-kwon
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.9 no.2
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    • pp.63-71
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    • 2011
  • A large volume of uranium electrokinetic leachate has been generated during the electrokinetic decontamination to remove uranium from contaminated soil. The treatment technology for the reuse of the uranium leachate was developed. The concentration of uranium in the generated uranium leachate was 180 ppm and concentrations of Mg(II), K(I), Fe(II), and Al(III) ions ranged from 20 ppm to 1,210 ppm. The treatment process for uranium leachate consisted mainly of mixing and cohesion, precipitation, concentration, and filtration. In order to obtain the pH=11 of a precipitate solution, the calcium hydroxide needs to be 3.0g/100ml and the sodium hydroxide needed to be 2.7g/100ml. The results of several precipitation experiments showed that a mixture of NaOH+0.2g alum+0.15g magnetite was an optimal precipitant for filtration. The average particle size of precipitate with NaOH+alum+0.15g magnetite was $600\;{\mu}m$. Because the total value of metal concentrations in supernatant at pH=9 was the smallest, sodium hydroxide should be added with 0.2g alum and 0.15g magnetite for pH=9 of leachate.

U.S. Policy and Current Practices for Blending Low-Level Radioactive Waste for Disposal (저준위 방사성폐기물의 혼합 관련 미국의 정책과 실제 적용)

  • Kessel, David S.;Kim, Chang-Lak
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.14 no.3
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    • pp.235-243
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    • 2016
  • In the near future, many countries, including the Republic of Korea, will face a significant increase in low level radioactive waste (LLW) from nuclear power plant decommissioning. The purpose of this paper is to look at blending as a method for enhancing disposal options for low-level radioactive waste from the decommissioning of nuclear reactors. The 2007 U.S. Nuclear Regulatory Commission strategic assessment of the status of the U.S. LLW program identified the need to move to a risk-informed and performance-based regulatory approach for managing LLW. The strategic assessment identified blending waste of varying radionuclide concentrations as a potential means of enhancing options for LLW disposal. The NRC's position is that concentration averaging or blending can be performed in a way that does not diminish the overall safety of LLW disposal. The revised regulatory requirements for blending LLW are presented in the revised NRC Branch Technical Position for Concentration Averaging and Encapsulation (CA BTP 2015). The changes to the CA BTP that are the most significant for NPP operation, maintenance and decommissioning are reviewed in this paper and a potential application is identified for decommissioning waste in Korea. By far the largest volume of LLW from NPPs will come from decommissioning rather than operation. The large volumes in decommissioning present an opportunity for significant gains in disposal efficiency from blending and concentration averaging. The application of concentration averaging waste from a reactor bio-shield is also presented.

Properties of Nanocomposites Based on Polymer Blend Containing PVDF, Carbon Fiber and Carbon Nanotube (PVDF를 포함한 고분자 블렌드와 탄소섬유/탄소나노튜브를 이용한 복합재료의 특성)

  • Kim, Jeong Ho;Son, Kwonsang;Lee, Minho
    • Applied Chemistry for Engineering
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    • v.25 no.1
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    • pp.14-19
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    • 2014
  • Nanocomposites based on poly(methyl methacrylate) (PMMA)/poly(vinylidene fluoride) (PVDF) and poly(ethylene terephthalate) (PET)/(PVDF) blended with carbon fibers (CF) and carbon nanotube (CNT) were prepared by melt mixing in the twin screw extruder. Morphologies of the PMMA/PVDF/CF/CNT and PET/PVDF/CF/CNT nanocomposites were investigated using SEM. The aggregation of CNT was observed in PMMA/PVDF/CF/CNT nanocomposites while the good dispersion of CNT was shown in PET/PVDF/CF/CNT nanocomposites. In SEM image of PET/PVDF/CF/CNT nanocomposite, the CNT were mainly located at the PET domain of phase-separated PET/PVDF blend due to the ${\pi}-{\pi}$ interaction between the phenyl ring of PET and graphite sheet of the CNT's surface. In addition, a fairly good compatibility between PET/PVDF matrix and CF was shown in the SEM image. In the case of PET/PVDF nanocomposites blended with the co-addition of CF and CNT, the volume electrical resistivity decreased while no change was observed in PMMA/PVDF/CF/CNT composites. The degree of CNT dispersion in morphology results was consistent with the electrical conductivity results. From the DSC results, the crystallization temperature (Tc) of PET/PVDF/CF/CNT nanocomposites increased due to the co-addition of CF and CNTs acting as a nucleating agent. Flexural modulus of PET/PVDF/CF/CNT were sharply enhanced due to increasing the interaction between PET and CF.

A Bibliographical Study of Dock(Korean rice cake) (떡류(類)의 문헌적(文獻的) 고찰(考察) -(1670년${\sim}1943$년의 우리말 조리서를 중심으로)-)

  • Mang, Hae-Yull;Lee, Hyo-Gee
    • Journal of the Korean Society of Food Culture
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    • v.3 no.2
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    • pp.153-162
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    • 1988
  • $D{\acute{o}}ck$ (Korean rice cake) is a peculiar food of Korea made of grain. By means of cooking from, it is defined as 'Pulvberzed food of grain' $D{\acute{o}}ck$ was one of the daily food, but development of boild rice had narrowed it's use to the food of festive days and ceremonies. $D{\acute{o}}ck$ is used as a main food of all Kinds of ceremonies from one's birth to death, such as the Three seven day(a baby's twenty-first day of life), one hunderdth day, birthday, wedding, both brithday, funeral and sacrifical rites, vocational ceremonies, such as a sacrifice to spirits and a srevics for a big catch of fish. It is also used as a present and seasonal food. A large variety of $D{\acute{o}}ck$ is available and its recipe is scientific and reasonable. In this treatise, the Kinds of $D{\acute{o}}ck$ and the frequency of them, the material, the recipe, the measuring unit of material, cooking kitchen utensils and the cooking terms are studied from the books published in Korea from 1670 to 1943. 1. $D{\acute{o}}ck$ was classified as Tcbin $D{\acute{o}}ck$(steamed), Chin $D{\acute{o}}ck$(strikn), Chijin $D{\acute{o}}ck$(fried) and Salmun $D{\acute{o}}ck$(boiled), according to its way of cooking. 2. There were 122 Kinds of $D{\acute{o}}ck$, 57 were Tchin $D{\acute{o}}ck$, 35 Chin $D{\acute{o}}ck$, 20 Chijin $D{\acute{o}}ck$, and 10 Salmun $D{\acute{o}}ck$. 3. There were 34 Kinds of measuring units. Of them, 13 for volume, 4 for weight, 9 for quantity, 4 for length and 4 for the rest. 4. There were 55 Kinds of cooking Kitchen utensils but now many of them are not used because of mechanization or automation of tools of living. 5. There were 143 Kinds of cooking terms. Of them 49 for the preparing process, 25 for the mixing process, 27 for well-forming process 10 for process of getting ready to cook, 14 for heating process, 10 for cutting process, 5 for dishin process and 3 for process of soaking in sugar or honey.

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Effect of Wheat Flour Brew with Bifidobacterium bifidum on Rheological Properties of Wheat Flour Dough (Bifidobacterium bifidum을 이용한 밀가루 brew가 반죽의 이화학적 성질에 미치는 영향)

  • Cho, Nam-Ji;Lee, Si-Kyung;Kim, Sung-Kon;Joo, Hyun-Kyu
    • Korean Journal of Food Science and Technology
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    • v.30 no.4
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    • pp.832-841
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    • 1998
  • In order to economically utilize flour brew with Bifidobacterium bifidum as a bread improver, the effect of flour brew on the rheological properties of dough, growth curve and acid production, and symbiosis with yeast were investigated. Growth of bifidobacteria was not increased more than initial seed volume but was consistent during 24 hours of incubation. pH was decreased and T.T.A was increased up to 12 hours of incubation. Symbiosis between bifidobacteria and yeast was little. Bifidobacteria produced more lactic acid than acetic acid in flour brew and the opposite in skim milk broth. This result was inferred from Lactobacillus sp. inherent in flour. On rheological properties of dough, farinograms of flour showed progressively decreasing baking absorption, mixing time and stability as the amount of flour brew increased. The validation of extensograms showed that R/E ratio linearly increased with increment of flour brew, and nearly doubled in all treatments comparing to that of control, which suggest the reduction of actual fermentation time. On visco/amylograms, malt index increased with addition of flour brew, accordingly showing the decrease in viscosity. Break down and set back value decreased with increment of flour brew, suggesting that staling rate of bread can be delayed.

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Improvement of Cycle Performance of Graphite-Silicon Monoxide Mixture Negative Electrode in Lithium-ion Batteries (흑연과 실리콘 일산화물의 혼합물로 구성된 리튬이온 이차전지용 음극의 사이클 성능개선 연구)

  • Kim, Haebeen;Kim, Tae Hun;Ryu, Ji Heon
    • Journal of the Korean Electrochemical Society
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    • v.22 no.4
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    • pp.155-163
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    • 2019
  • Mixture electrodes of a graphite having a good cycle performance and a silicon monoxide (SiO) having a high capacity are fabricated and their cycle performances are evaluated as negative electrodes for lithium-ion batteries. The electrode prepared by mixing the natural graphite and carbon-coated SiO in a mass ratio of 9:1 shows a reversible capacity of $480mAh\;g^{-1}$, 33% higher than that of graphite. However, the capacity deteriorates continuously upon cycling due to the volume change of silicon monoxide. In this study, the factors that can improve the cycle performance have been discussed through the change in the configurations of the electrode and the electrolyte. The electrode using the carboxymethyl cellulose (CMC) binder shows the best cycle performance compared to the conventional binders. The electrode sing the CMC and styrene-butadiene rubber (SBR) binder not only has almost the similar cycle characteristics with the electrode using the CMC binder but also has the better rate capability. When the fluoroethylene carbonate (FEC) is used as an electrolyte additive, the cycle life is improved. However, the electrolyte with 5 wt% of FEC is appropriate because the rate capability decreases when the content of FEC is increased to 10 wt%. In addition, when the mass loading of the electrode is lowered, the cycle performance is greatly improved. Also, enhanced cycle performance is achieved using the roughened Cu current collector polished by abrasive paper.

Synthesis and Electrochemical Properties of Zn and Al added LiNi0.85Co0.15O2 Cathode Materials (Zn와 Al을 첨가한 LiNi0.85Co0.15O2 양극활물질의 제조 및 전기화학적 특성평가)

  • Kim, Su-Jin;Seo, Jin-Seong;Na, Byung-Ki
    • Korean Chemical Engineering Research
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    • v.59 no.1
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    • pp.42-48
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    • 2021
  • Zn and Al added LiNi0.85Co0.15O2 cathode materials were synthesized to improve electrochemical properties and thermal stability using a solid-state route. Crystal structure, particle size and surface shape of the synthesized cathode materials was measured using XRD (X-ray diffraction) and SEM (scanning electron microscopy). CV (cyclic voltammetry), first charge-discharge profiles, rate capability, and cycle life were measured using battery cycler (Maccor, series 4000). Strong binding energy of Al-O bond enhanced structure stability of cathode material. Electrochemical properties were improved by preventing cation mixing between Li+ and Ni2+. Large ion radius of Zn+ increased lattice parameter of NC cathode material, which meant unit-cell volume was expanded. NCZA25 showed 80% of capacity retention at 0.5 C-rate during 100 cycles, which was 12% higher than that of NC cathode. The discharge capacity of NCZA25 showed 104 mAh/g at 5 C-rate. NCZA25 achieved 36 mAh/g more capacity than that of NC cathod. NCZA25 cathode material showed excellent rate capability and cycling performance.

Quality characteristics of Jeung-pyun with different amount of Makgeolli (막걸리 첨가량을 달리한 증편의 품질 특성)

  • Kim, Jin-Seong;Choi, JinHee;Choi, Hae-Yeon
    • Korean Journal of Food Science and Technology
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    • v.54 no.2
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    • pp.196-202
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    • 2022
  • In this study, the quality characteristics of Jeung-pyun with different amounts of Makgeolli (50, 100, 150, and 200 mL) were investigated, and standardization of the Jeung-pyun production process is suggested. Higher Makgeolli contents resulted in an increase in Jeung-pyun qualities such as the b value, air cell size, springiness, and cohesiveness, whereas Jeung-pyun characteristics such as the L values, pH, number of air cells, hardness, and gumminess significantly decreased. The specific volume was highest following method M-150, and the expansion rate was lowest following method M-200. Altering the Makgeolli content did not significantly differ in moisture content and b values. In the sensory evaluation results, the M-150 method produced the highest-ranking results for all tested items (i.e., overall acceptability, appearance, flavor, taste, and texture). Therefore, this study suggests that Jueng-pyun produced with the M-150 mixing ratio has excellent quality and sensory characteristics. Furthermore, the results of this study can be used as preliminary data for the standardization of Jueng-pyun production.