• Journal of Environmental Science International
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• v.18 no.11
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• pp.1299-1307
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• 2009

In order to measure in-situ suspended particle size, volume concentration of suspended particulate matter and current speed, mooring observation was performed at the Gwangyang Bay by using of an optical instrument, 'LISST-100' and an acoustic instrument, 'ADV'(St. S1). And the sediment flux was obtained based on the concentration of suspended particulate matter and current speeds measured at three lines of Gwangyang Bay during ebb and flood tide of August 2006. To investigate the spatial variation of suspended particulate matter, profiling observations were measured difference echo intensity and beam attenuation coefficient by using of ADCP and Transmissometer (Line A, B, C). The suspended sediment flux rate at the mouth of Gwangyang Bay was observed to be higher during asymmetrical than symmetrical of current speeds. The flux of suspended particulate matter concentration and current speeds were transported to southeastern direction of surface layer and northwestern direction of bottom layer at the western area at line A of Gwangyang Bay. Small suspended particles have been found to increase attenuation and transmission more efficiently than similar large particles using acoustic intensity (ADV/ADCP) or optical transmit coefficient (LISST-100/Transmissometer). The application and problems as using optical or acoustic instruments will be detected for use in time varying calibrations to account for non-negligible changes in complex environments in situ particle dynamics are poorly understood.

• Journal of the Korean Geotechnical Society
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• v.23 no.11
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• pp.49-58
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• 2007

Numerical experiments using a distinct element code (PFC3D) were carried out for the analysis of grout-material transfer in soil layers and also for the analysis of increase in mechanical strength after permeation grouting. For rapid analysis, up-scaling analysis in length scale was adopted, and the following observations were made from the numerical experiments. Firstly, the relative size of grout material with respect to the in situ soil particles controlled the transfer distance of the grout particles. When the size of grout particle was 0.2 to 0.25 times of the in situ soil particles, clogging of pore spaces among the in situ soil particles occurred, resulting in restricted propagation of grout particles. It was also found that there was a threshold value in the size of grout particle. Below the threshold value, the transfer distance of the grout particle did not increase with the decrease of particle size of the grout material. Secondly, the increase in cohesion and internal friction angle was observed in the numerical specimen with grouting treatment, but not with the untreated specimen.

• Economic and Environmental Geology
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• v.46 no.5
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• pp.425-444
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• 2013

This study was carried out in order to determine the remediation of total petroleum hydrocarbons (TPHs), trichloroethylene (TCE), perchloroethylene (PCE), benzene, toluene, ethylbenzene and xylenes (BTEX) compounds for non-aqueous phase liquids (NAPLs) using in-situ air sparging (IAS) / vapor extraction (VE) with the marine sediments of Mandol, Hajeon, Sangam and Busan, South Korea. Surface sediment of Mandol area had sand characteristics (average particle size, 1.789 ${\Phi}$), and sandy silt characteristics (average particle size, 5.503 ${\Phi}$), respectively. Sangam surface sediment had silt characteristics (average particle size, 5.835 ${\Phi}$). Sediment characteristics before experiment in the Busan area showed clay characteristics (average particle size, 8.528 ${\Phi}$). TPHs level in the B1 column of Mandol, Hajeon, Sangam, and Busan sediments were 2,459, 6,712, 4,348, and 14,279 ppm. B2 (3 L/min) to B5 (5 L/min) columns reduced 99.5% to 100.0% of TCE and 93.2% to 100.0% of PCE. Removal rates of TCE, PCE, and BTEX are closely correlated (0.90-0.99) with particle sizes and organic carbon concentrations. However, TPHs (0.76) and benzene (0.71) showed the poorer but moderate correlations with the same parameters.

• Textile Coloration and Finishing
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• v.15 no.5
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• pp.327-332
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• 2003

In this study, the polyurethane microcapsules for non-aqueous dyeing containing iron oxide and disperse dyes were prepared by in-situ polymerization method using hexamethylene diisocyanate(HDI) with ethylene glycol(EG). And the size, shape, and particle size distribution of microcapsules prepared were investigated. The size and shape of microcapsule were observed by optical microscope and scanning elecron microscope. The particle size distribution was analyzed by particle size analyzer. The microcapsule size and its distribution were largely effected by the existance of surface active agent in the system. When a surfactant did not exist in the system, the size distribution of microcapsules prepared was much uneven. By adding a surfactant, this phenomenon was disappeared. And the size of microcapsule was also effeced by the hydrophobicity of core material(disperse dye). It was considered due to the difference of dispersity of core materials. And the size of microcapsule prepared was inversely proportional to the stirring speed.

• Textile Coloration and Finishing
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• v.10 no.2
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• pp.37-44
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• 1998

In this study, the polyurethane microcapsules containing disperse dye were prepared by in-situ polymerization method using hexamethylene diisocyanate (HDI, aliphatic type) and m-xylene diisocyanate(XDI, aromatic type) with ethylene glycol (EG) And the size, shape, particle size distribution, and breaking behavior of microcapsules prepared were investigated. The size and shape of microcapsule were observed by scanning electron microscope (SEM) . The particle size distribution was analyzed by image analyzer. The breaking behavior of microcapsule was checked by measuring the optical density of solution that the disperse dye was dissolved after the microcapsule was broken by constant pressure. The particle size was inversely proportional to the stirring speed, and the size of microcapsule prepared from HDI and EG was smaller than that of microcapsule prepared from XDI and EG. Aliphatic type microcapsule was broken easily, compared with aromatic type one. It was considered due to the difference of reactivity between HDI and XDI. And the microcapsule prepared by stirring strongly was broken easily.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.860-863
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• 2005

The microcapsules containing fragrant oil as functional material were prepared by in-situ polymerization with prepolymer that was made from melamine-formaldehyde (MF) as wall material of microcapsules. The effects of polymerization variables, such as the nature and concentration of surfactants, stirring rate, and stirring time, on the size and distribution of the particles were investigated. Fourier transform-infrared spectroscopy (FT-IR), thermal analysis, particle size analysis, scanning electron microscopy (SEM) observation were used to investigate the characteristics of microcapsules. Through the FT-IR and SEM analysis, we found that the prepared microcapsules were containing fragrant oil and the shape of particle was spherical. The nature and concentration of surfactants, stirring rate, and stirring time had profound effects on the particle size and particle size distribution.

• Journal of The Korean Society of Grassland and Forage Science
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• v.34 no.4
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• pp.288-295
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• 2014

This study was conducted to evaluate the effect of mixing time for TMR (total mixed rations) mixed with corn silage on particle size, peNDF (physically effective neutral detergent fiber), laceration, and ruminal in situ dry matter degradation. The study also aimed to evaluate the effect of consumption of the TMR on the milk yield and milk components of mid-lactational dairy cows. TMRs were mixed for 30 minutes (T1) and 50 minutes (T2) using the same material. All samples were then analyzed with a Penn State Particle Size Separator (PSPS). The particle size of T1 was significantly lower in the bottom pan (8 mm>) than that of T2 (p<0.01). $peNDF_{&gt;8.0}$ was significantly higher in T1 (17.18%) than in T2 (13.85%) (p<0.01). For ruminal in situ dry matter degradation of particle retention (>19 mm), no significant difference was found after 72 hours incubation, although T1 degradation was significantly higher after 24 hours incubation (p<0.01). Milk yield was no different between the groups of cows, whereas the milk fat from T1 fed cows was significantly higher (p<0.01). The results show that feeding TMR mixed for 30 minutes to dairy cows may improve the physical value of forage without negative effects on the milk yield and milk components.

• Journal of the Korean Applied Science and Technology
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• v.18 no.4
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• pp.273-284
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• 2001

A series of microcapsule were synthesized by using several PCM(Phase Change Material) as a core material and gelatin/arabic gum, melamine/formaldehyde as a shell material. Coacervation technique and in situ polymerization were adopted in synthesizing microcapsules. In the microencapsulation by coacervation, tetradecane and octadecane were used as core materials. In the microencapsulation by situ polymerization tetradecane, pentadecane, hexadecane, heptadecane, octadecane, and nonadecane were used as core material. The synthesized microcapsule was examined to observe the shape of the microcapsule. The particle size analysis was performed by particle size analyzer. The thermal properties(e.g. melting point, heat of melting, crystallization temperature, heat of crystallization, differences between melting point and crystallization temperature) were obtained by DSC(Differential Scanning Calorimeter). The stirring rate effect was investigated during the microencapsulation. It was found that with increasing the stirring rate much smaller microcapule was produced. However, this did not necessarily lead to formation of spherical microcapsule.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.1
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• pp.15-20
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• 2015

During the liquefaction of hydrogen, the ortho hydrogen is converted into the para form with heat release that evaporates the liquefied hydrogen into the gaseous one backwards. The ortho-para conversion catalysts are usually used during liquefaction to avoid such boil-off. In order to compare and analyze the performance of the ortho-para hydrogen conversion catalysts, in-situ FT-IR device was designed and manufactured to measure the para hydrogen conversion rate in real-time. $LaFeO_3$ and $La_{0.7}Sr_{0.3}Cu_{0.3}Fe_{0.7}O_3$ perovskite catalysts were prepared by the citrate sol-gel method and their spin conversion characteristics from ortho to para hydrogen were investigated by in-situ FTIR spectroscopy at 17K. It was found that the spin conversion was affected by surface area, particle size, and crystallite size of the catalysts. Thus, the $La_{0.7}Sr_{0.3}Cu_{0.3}Fe_{0.7}O_3$ perovskite catalyst that had higher surface area, higher crystallite size, and smaller particle size than $LaFeO_3$ showed the better spin conversion property of 32.3% at 17K in 120min interaction with the perovskite catalysts.

• Environmental Engineering Research
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• v.17 no.3
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• pp.167-174
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• 2012

In situ particle size spectra are obtained from two sequent cruises in order to evaluate the physical consequences of suspended particulate matters caused by episodic storm runoff from the Santa Ana River watershed, an urbanized coastal watershed. Suspended particles from various sources including surface runoff, near-bed resuspension, and phytoplankton are identified in empirical orthogonal function (EOF) analysis and an entropy-based parameterization (Shannon entropy). The first EOF mode is associated with high turbidity and fine particles as indicated by the elevated beam attenuation near the Santa Ana River and Newport Bay outlets, and the second EOF mode explains the suspended sediment dispersal and particle coarsening at the near-surface plume. Chlorophyll particles are also distinguished by negative magnitudes of the first EOF mode, which is supported by the relationship between fluorescence and beam attenuation. The integrated observation between the first EOF mode and the Shannon entropy index accentuates the characteristics of two different structures and/or sources of sediment particles; the near-surface plumes are originated from runoff water outflow, while the near-bottom particles are resuspended due to increased wave heights or mobilizing bottom turbidity currents. In a coastal pollution context, these methods may offer useful means of characterizing particle-associated pollutants for purposes of source tracking and environmental interpretation.