• Title/Summary/Keyword: Mixing Pattern

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Improving the Photo-stability of p-aramid Fiber by TiO2 Nanosol (TiO2 sol-gel 합성에 의한 파라 아라미드 섬유의 내광성 증진 연구)

  • Park, Sung-Min;Kwon, Il-Jun;Sim, Ji-Hyun;Lee, Jae-Ho;Kim, Sam-Soo;Lee, Mun-Cheul;Choi, Jong-Seok
    • Textile Coloration and Finishing
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    • v.25 no.2
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    • pp.126-133
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    • 2013
  • Although para-aramid fibers poss higher mechanical properties, they show very low resistance to sunlight exposure. This paper studied on the effect of nano-sol coated $TiO_2$ to improve the photo-stability of p-aramid fibers. Titanium dioxides were prepared by sol-gel method from titanium iso-propoxide at different R ratio ($H_2O$/titanium iso-propoxide). All samples were characterized by XRD, TEM and UV-vis spectrometer. The mechanical properties of p-aramid fabrics by $TiO_2$ nano-sol coating before and after sunlight irradiation were measured with tensile tester. XRD pattern of titanium dioxide particles was observed by mixing phase together with rutile and anatase type. The results showed, after sunlight irradiation, the decreased mechanical properties of the fiber. Furthermore, the sunlight irradiation obviously deteriorated the surface and defected areas of the fiber severely by photo-induced chain scission and end group oxidation in air.

Change in Physical Properties of Engine oil Contaminated with Diesel (경유 혼입에 의한 엔진오일 물성 변화)

  • Lim, Young-Kwan;Lee, Jong-Eun;Na, Yong-Gyu;Kim, Jong-Ryeol;Ha, Jong-Han
    • Tribology and Lubricants
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    • v.33 no.2
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    • pp.45-51
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    • 2017
  • Engine oil is a substance used for the lubrication of internal combustion systems. However, in some case, defects in engine systems may contaminate engine oil with fuel. Contaminated engine oil can cause problems in the normal functioning of a vehicle. In this study, we investigate the functional properties of engine oil contaminated with diesel fuel. The test results indicate that the engine oil contaminated with diesel fuel has low flash point, pour point, density, kinematic viscosity and cold cranking simulator value. The contaminated engine oil which has low plash point can cause fire and explosion accident. Furthermore, a four ball test indicates that the contaminated engine oil increases wear scar to poor lubricity. Moreover, we investigate the GC pattern using SIMDIST (simulated distillation) for determination of diesel in engine oil. The SIMDIST analytic result, diesel was detected at earlier retention time than engine oil in chromatogram. Thus the SIMDIST method can define whether engine oil is contaminated by diesel fuel or not. We can use the SIMDIST method for the diagnosis of oil condition instead of analyzing other physical properties that require many analytic instruments, large volume of oil sample and long analysis time.

Empirical Orthogonal Function Analysis of Seawater Temperature in the Southeastern Hwanghae (東南黃海에서 海水溫度의 EOF 分析)

  • 이흥재;방인권
    • 한국해양학회지
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    • v.21 no.4
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    • pp.193-202
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    • 1986
  • Spatio-temporal variabilities of seawater temperature at 0 and 30m in the southeastern Hwanghae were studied by variance and empirical orthogonal function(EOF) analysis of long records of temperature between 1967 and 1982. The spatial distribution of monthly mean sea surface temperature has a pattern similar to the long-term annual mean which decreases from south to north. On the contrary, the total variance computed from the annual mean of sea surface temperature(SST) increases from south to north. The variance of SST is found to be two times greater than that at 30m in the study area except coastal area south of Kyunggi Bay. The important variance of temperature seem s to be closely associated with the seasonal change of temperature because the first and second modes of EOF having a seasonal cycle explain 97.6% and 85.2% of variances at 0 and 30m, respectively. There is a large difference in temperature between the northern and southern parts of the study area during winter, while the difference becomes very small during summer. This might reflect that in summer the heat gain of sea surface from the incoming radiation is much more important than the heat loss or the oceanic heat advection. In summer coastal waters south of the Kyunggi Bay and around Mokpo are observed to be colder than offshore waters due to tidal mixing.

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A study on the effect of agitation speeds for the optimization of manufacturing process of autonomic microcapsules (자가치료용 마이크로캡슐 제조공정 최적화를 위한 교반속도 영향 연구)

  • Yun, Seong-Ho;Kim, Sang-Deok
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.3
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    • pp.51-59
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    • 2006
  • The physical characteristics of autonomic microcapsules manufactured with various agitation speeds in a stirred tank were observed experimentally by a particle size analyzer and an optical microscope. The flow characteristics in a stirred tank were also investigated through a 3-dimensional numerical simulation to understand the manufacturing process of autonomic microcapsules. According to the results, we found that the agitation speed was the important factor to determine the sizes of microcapsules. The impeller-induced flow allowed the jet and tip-vortex pair components in the mixed fluid of a stirred tank. The vorticity around the blades in the impeller was increased as increasing the agitation speed. In addition, the size of autonomic microcapsules was strongly affected on the small scale mixing pattern such as a tip-vortex pair.

Application of CE-QUAL-W2 [v3.2] to Andong Reservoir: Part I: Simulations of Hydro-thermal Dynamics, Dissolved Oxygen and Density Current

  • Bhattarai, Prasid Ram;Kim, Yoon-Hee;Heo, Woo-Myoung
    • Korean Journal of Ecology and Environment
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    • v.41 no.2
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    • pp.247-263
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    • 2008
  • A two-dimensional (2D) reservoir hydrodynamics and water quality model, CE-QUAL-W2, is employed to simulate the hydrothermal behavior and density current regime in Andong Reservoir. Observed data used for model forcing and calibration includes: surface water level, water temperature, dissolved oxygen and suspended solids concentration. The model was calibrated to the year of 2003 and verified with continuous run from 2000 till 2004. Without major adjustments, the model accurately simulated surface water levels including the events of large storm. Deep-water reservoirs, like Andong Reservoir, located in the Asian Monsoon region begin to stratify in summer and overturn in fall. This mixing pattern as well as the descending thermocline, onset and duration of stratification and timing of turnover phenomenon were well reproduced by the Andong Model. The temperature field and distinct thermocline are simulated to within $2^{\circ}C$ of observed data. The model performed well in simulating not only the dissolved oxygen profiles but also the metalimnetic dissolved minima phenomenon, a common1y occurring phenomenon in deep reservoirs of temperate regions. The Root Mean Square Error (RMSE) values of model calibration for surface water elevation, temperature and dissolved oxygen were 0.0095 m, $1.82^{\circ}C$, and $1.13\;mg\;L^{-1}$, respectively. The turbid storm runoff, during the summer monsoon, formed an intermediate layer of about 15 m thickness, moved along the metalimnion until being finally discharged from the dam. This mode of transport of density current, a common characteristic of various other large reservoirs in the Asian summer monsoon region, was well tracked by the model.

Influences of Oxygen Partial Pressure and Annealing Time on Microstructure and Magnetic Properties of Hexagonal Barium-Ferrite Thin Films (Hexagonal Barium-Ferrite 박막의 미세구조와 자기적 특성에 미치는 산소분압과 열처리 시간의 영향)

  • 김웅수;김동현;남인탁;홍양기
    • Journal of the Korean Magnetics Society
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    • v.10 no.6
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    • pp.285-290
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    • 2000
  • BaM thin films were prepared by using RF magnetron sputtering system at room temperature, and then successively annealed to crystallize at 850$\^{C}$ using RTA. The structure and magnetic properties of post-annealed BaM films have been investigated using XRD and VSM, respectively. The dependences of partial oxygen gas pressure (Po2) on the characteristics of BaM films were investigated. Although mixing of spinel and BaM phase only was identified in 0.5 mTorr oxygen partial pressure, BaM phase only was identified in the range from 1 to 3 mTorr oxygen partial pressure. The saturation magnetization and perpendicular coercivity of BaM thin films decreases with increase of Po2 in the range of Pot between 0.5 and 3 mTorr.

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Elucidation of Antioxidant Activity of Phosvitin Extracted from Egg Yolk using Ground Meat

  • Jung, Samooel;Jo, Cheo-Run;Kang, Min-Gu;Ahn, Dong-Uk;Nam, Ki-Chang
    • Food Science of Animal Resources
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    • v.32 no.2
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    • pp.162-167
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    • 2012
  • Phosvitin was extracted from a chicken egg yolk and the iron-binding, along with antioxidative activity of the extracted phosvitin, was determined after mixing with ground beef at the concentrations of 100 and 500 mg/kg of meat. The electrophoretic pattern of the extracted phosvitin on SDS-PAGE was found to be identical to that of the standard phosvitin. The extracted phosvitin at $1,000{\mu}g$/mL showed an ability to bind approximately 65% of the iron in a 3 mM iron solution. Lipid oxidation was inhibited in the ground beef mixed with 500 mg/kg of the extracted phosvitin, during storage at $4^{\circ}C$ compared to that of the control (p<0.05). Additionally, color stability of ground beef containing the extracted phosvitin was enhanced (p<0.05). The pH, cooking loss, texture, and sensory properties of the ground beef were not affected, by adding up to 500 mg/kg of the extracted phosvitin. This result suggests that the phosvitin extracted from egg yolk could be used as an antioxidant reagent. In particular, phosvitin would be more amenable for use in meat products because it is a natural protein derived from animal products.

Preparation and Characterization of Bovine Serum Albumin-loaded Cationic Liposomes: Effect of Hydration Phase

  • Park, Se-Jin;Jeong, Ui-Hyeon;Lee, Ji-Woo;Park, Jeong-Sook
    • Journal of Pharmaceutical Investigation
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    • v.40 no.6
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    • pp.353-356
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    • 2010
  • Although liposomes have been applied as drug delivery systems in various fields, the usage was limited due to the low encapsulation efficiency compared to other carrier systems. Here, cationic liposomes were prepared by mixing 1,2-dioleoyl-3-trimethylammoniopropane (DOTAP) as a cationic lipid, 1,2-dioleoyl-sn-glycerol-phosphoethanolamine (DOPE) and cholesterol (CH), and the liposomes were hydrated by varying the aqueous phases such as phosphate-buffered saline (PBS), 5% dextrose, and 10% sucrose in order to improve the encapsulation efficiency of bovine serum albumin (BSA). The particle size and zeta potential were determined by dynamic light scattering method and in vitro release patterns were investigated by spectrophotometry. Particle size and zeta potential of liposomes were varied depending on the ratio of DOTAP/DOPE/CH in range of 270-350 nm and 0.8-9.7 mV, respectively. Moreover, the addition of polyethylene glycol (PEG) improved the encapsulation efficiency from 37% to 43% as well as reduced particle sizes of liposomes while the liposomes were hydrated in PBS. When the liposomes were hydrated with 10% sucrose, the encapsulation efficiency of BSA was higher than any other groups. Whereas PBS was used as hydration solution, lower encapsulation efficiency was obtained compared with other groups. More than 60% of BSA was released from the liposomes hydrated with 10% sucrose; thereafter another 20% of BSA was released. Therefore, release pattern of BSA from cationic liposomes was extended release in this study. From the results, cationic liposomes dispersed in 10% sucrose would be potential carrier with high encapsulation efficiency.

A Study on the CFD Analysis and Estimation of the Energy Efficiency of Cryogenic Chamber for Extreme Climate Test (극한 환경 시험을 위한 극저온 챔버의 CFD 해석 및 에너지 효율 평가에 관한 연구)

  • Kang, Yul-Ho;Kim, Min-Kyu;Park, Warn-Gyu
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.28 no.2
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    • pp.81-88
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    • 2016
  • There are many types of national and international standards for low temperature tests depending on the products. This study conducted CFD analysis and estimation of the energy efficiency of the chamber both with and without a test object by considering variations of COP and specific volume according to temperature. The supply air was located in the upper area to compare the cooling performance for each location using various outlets in mixed ventilated conditions. For cases without the test object, the air temperature of the upper supply and center extract on the opposite side type chamber cooled faster than other areas by 4.3~29.8%. However, for cases with the test object, the object temperature of the upper supply and lower extract type chamber cooled faster than the other areas by 7.2~31.5%. The cooling efficiency of the air inside the chamber and the test object did not show the same pattern, which indicates the need to consider the cooling performance by not only the air but also the test object in the cryogenic chamber design for testing.

Study on the Corrosion Characteristics in the Slag Line of SEN Oxide Refractory (산화물계 SEN내화물의 슬래그 라인부 침식특성 연구)

  • Sung, Young Taek;Son, Jeong Hun;Lee, Sung Seok;Bae, Dong Sik
    • Korean Journal of Materials Research
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    • v.24 no.1
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    • pp.53-59
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    • 2014
  • The corrosion resistance of submerged entry nozzle (SEN) materials were investigated for high-class steel manufacturing. Composite samples were fabricated by mixing $ZrO_2$, $Al_2O_3$, MgO, mullite, spinel, and carbon. The raw materials were mixed with attrition milling, compacted in a uniaxial pressure of 200MPa and calcined at $1000^{\circ}C$ for 3 h in $N_2$ atmosphere. The bulk density and apparent porosity of the calcined samples were measured by the liquid displacement method in water using Archimedes's principle. The corrosion resistance of the samples were measured by cup test with mold powder at $1550^{\circ}C$ for 2 h. The microstructure and elemental analysis of samples were observed by scanning electron microscopy (SEM), energy dispersive spectrum (EDS), and X-ray diffraction pattern (XRD). The XRD result shows that the starting raw materials were crystalline phase. The microstructure of fabricated specimen was investigated before and after corrosion tests at $1000^{\circ}C$ and $1550^{\circ}C$ for 2h. $ZrO_2$-C composite showed good resistance in the slag corrosion test. Among the composite oxide materials, $ZrO_2-Al_2O_3$-C and $ZrO_2$-MgO-C showed better resistance than $ZrO_2$-C in the slag corrosion test. The diameter variation index of $ZrO_2$-C refractory was 16.1 at $1000^{\circ}C$ for 2 h. The diameter variation index of the $ZrO_2-Al_2O_3$-C refractory was larger than that of the $ZrO_2$-C refractory at $1550^{\circ}C$ for 2 h.