• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.1
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• pp.55-59
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• 1999

The Rapid Expansion of Supercritical fluid Solutions (RESS) process was applied to particles coating. Microcapsules prepared by spray drying were used as the core particles, and two kinds of paraffin were used as the coating materials. Supercritical $CO_{2}$ solutions of paraffin were expanded through the short nozzle into the bed that was fluidized by air. Extraction temperature and pressure were varied at $50~120^{\circ}C$, $150~200\;kg/\textrm{cm}^2$, respectively. The thickness of theoritical coating layer ws measured, and precipitate coating layer on surface was analyzed by using SEM, FT-IR. The release behaviors of $Mg^{2+}$ ions were inspected by atomic absorbance spectrophtometer.

• Journal of Soil and Groundwater Environment
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• v.27 no.4
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• pp.63-74
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• 2022

In analyzing heavy metals in soil samples, the standard protocol established by Korean Minstry of Environment (KSTM) requires two different pretreatments (A and B) based on soil particle size. Soil particles < 0.15 mm in diameter after sieving are directly processed into acid extraction (method A). However, if the quantity of soil particles < 0.15 mm are not enough, grinding of the particles within 0.15 mm ~ 2 mm is required (method B). Grinding is often needed for some field samples, especially for the soil samples retrieved from soil washing process that contain relatively large-sized soil grains. In this study, two soil samples with different particle size distribution were prepared and analyzed for heavy metals concentrations using two different pretreatment to investigate the effect of grinding. The results showed that heavy metal concentrations tend to increase with the increase of the fraction of small-sized particles. In comparison of the two pretreatments, pretreatment A yielded higher heavy metal concentration than pretreatment B, indicating significant influence of grinding on analytical results. This results suggest that the analytical values of heavy metals in soil samples obtained by KSTM should be taken with caution and carefully reviewed.

• Clean Technology
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• v.19 no.3
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• pp.212-218
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• 2013

The microparticles of 2-hydroxypropyl-${\beta}$-cyclodextrin (HP-${\beta}$-CD) were prepared using aerosol solvent extraction system (ASES) by employing supercritical carbon dioxide as an antisolvent, The effects of various process parameters such as temperature, pressure, solution concentration and solution flow rate on the formation of HP-${\beta}$-CD microparticles were investigated. The HP-${\beta}$-CD microparticles prepared by the ASES process were observed to consist of agglomerates of nano-sized (50-200 nm) particles. When an aqueous solution of ethanol was used as a solvent for HP-${\beta}$-CD, the HP-${\beta}$-CD particles were found to be spherical in shape and to become larger as the water content increased. It was confirmed that the micronization of HP-${\beta}$-CD using the ASES process could enhance the inclusion efficiency of ibuprofen/HP-${\beta}$-CD complexes significantly.

• Fisheries and Aquatic Sciences
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• v.4 no.1
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• pp.1-9
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• 2001

This paper describes a procedure extracting feature vector of a target cell more precisely in the case of identifying specified cell. The classification of object type is based on feature vector such as area, complexity, centroid, rotation angle, effective diameter, perimeter, width and height of the object So, the feature vector plays very important role in classifying objects. Because the feature vectors is affected by noises and holes, it is necessary to remove noises contaminated in original image to get feature vector extraction exactly. In this paper, we propose the following method to do to get feature vector extraction exactly. First, by Otsu's optimal threshold selection method and morphological filters such as cleaning, filling and opening filters, we separate objects from background an get rid of isolated particles. After the labeling step by 4-adjacent neighborhood, the labeled image is filtered by the area filter. From this area-filtered image, feature vector such as area, complexity, centroid, rotation angle, effective diameter, the perimeter based on chain code and the width and height based on rotation matrix are extracted. To prove the effectiveness, the proposed method is applied for yeast Zygosaccharomyces rouxn. It is also shown that the experimental results from the proposed method is more efficient in measuring feature vectors than from only Otsu's optimal threshold detection method.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.785-790
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• 2017

To collect zinc, Fe and Zn in spent pickling solution were extracted by using TBP (tributyl phosphate), and Zn was recovered from extracted solution to zinc oxalate particles by oxalic acid solution. The reusability of TBP solvent was also tested. The distribution coefficient of Zn was not affected by the concentration of Fe in spent pickling solution, almost constant with the values of 7.12~9.31 when extracted by TBP solvent. It was found that the extraction capacity of TBP solvent for Zn is higher than that for Fe. The extraction efficiency of Zn was higher than 95%, while most of Fe was left in aqueous phase. After the recovery, the used TBP solvent could be repeatedly reused for the extraction of Zn up to eight times. XRD analysis showed that zinc oxalate ($ZnC_2O_4$ $2H_2O$) was formed from the reaction of Zn-TBP and oxalic acid. From the results of SEM analysis, the formation of zinc oxalate particle was strongly affected by the concentration of oxalic acid. In summary, Zn in spent pickling solution was successfully separated and recovered with TBP solvent and oxalic acid solution, respectively.

• 연구논문집
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• s.30
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• pp.147-157
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• 2000

The filtered vacuum arc source (FVAS), which is adopted by magnetic filtering methode to remove the macro-particle in vacuum arc plasma, was composed of a torus structure with bending angle of 60 degree. The radius of torus was 266 mm, the radius of plasma duct was 80 mm and the total length was 600 mm. The magnet parts were consisted of one permanent magnet, one magnetic yoke and five solenoid magnets. The plasma duct was electrically isolated from the ground so that a bias voltage could be applied. The baffles inside plasma duct were installed in order to prevent the recoil effect of macro-particles. Graphite was used as the cathode material to coat the amorphic diamond film and its diameter was 80 mm. The amorphic diamond film attracts much attention due to its excellent mechanical, optical and tribological properties suitable for wide range of applications. The effects of solenoid magnet in plasma extraction were studied by computer simulation and experiment using Taguchi's method. The source and extraction magnet affected the arc stabilization. The extraction beam current was maximized with low value of the source magnet current and high value of the filtering magnet current. Optimum deposition condition was obtained when the currents of arc discharge, source, extraction, bending, deflection and outlet magnet were 30 A, 1 A, 3 A, 5 A, and 5 A, respectively.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2004.03a
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• pp.241-246
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• 2004

The ocean signal that reaches the detector of an imaging system after multiple interactions with the atmospheric molecules and aerosols was retrieved from the total signal recorded at the top of the atmosphere (TOA). A simple method referred to as 'Path Extraction' applied to the Landsat-TM ocean imagery of turbid coastal water was compared with the conventional dark-pixel subtraction technique. The shape of the path-extracted water-leaving radiance spectrum resembled the radiance spectrum measured in-situ. The path-extraction was also extended to the SeaWiFS ocean color imagery and compared with the standard SeaWiFS atmospheric correction algorithm, which relays on the assumption of zero water leaving radiance at the two NIR wavebands (765 and 865nm). The path-extracted water-leaving radiance was good agreement with the measured radiance spectrum. In contrast, the standard SeaWiFS atmospheric correction algorithm led to essential underestimation of the water-leaving radiance in the blue-green part of the spectrum. The reason is that the assumption of zero water-leaving radiance at 755 and 865nm fails due to backscattering by suspended mineral particles. Therefore, the near infrared channels 765 and 865nm used fur deriving the aerosol information are no longer valid for turbid coastal waters. The path-extraction is identified as a simple and efficient method of extracting the path radiance largely introduced due to light interaction through the complex atmosphere carried several aerosol and gaseous components and at the air-sea interface.interface.

• Journal of Soil and Groundwater Environment
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• v.9 no.4
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• pp.52-61
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• 2004

In order to remediate soils contaminated with oxyanionic As and cationic Zn and Ni through the pilot-scale acid washing, the effectiveness of acid washing and the properties of contaminated soils, fine soil particle and dissolved contaminants were evaluated. $H_{2}SO_4\;and\;H_{3}PO_4$ washing at pH $2{\sim}3$ enhanced the removal of As by the presence of competitive oxyanions and HCl washing effectively removed simultaneously As, Zn and Ni. The effectiveness of soil washing was little enhanced above the critical reaction time, and the carbonate, Fe/Mn oxide and organic/sulfides associated fraction were dominantly removed. The washing of coarse soil particles was highly efficient, but that of fine soil particles($<74{\mu}m$) was recalcitrant due to the enrichment with contaminants. Moreover, the physical separation of fine particles($<149{\mu}m$) enhanced the overall efficiency of soil washing. Therefore, both chemical extraction and separation of fine soil particles showed the high effectiveness of soil washing in the intersection point to minimize the amount of fine soil particles and to maximize the chemical extraction of contaminants.

• Journal of Periodontal and Implant Science
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• v.25 no.3
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• pp.557-567
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• 1995

The purpose of this study was to investigated the effect of root planing and decalcified freeze dried allografts on the resorption of transplanted roots and the healing of preveously diseased recipient extraction sockets. The experimental chronic periodontitis was induced by elastic ligatures on the 2nd and 3rd mandibular premolars of 4 adult dogs, and after 8 weeks, crowns were removed and the teeth extracted. The extracted roots were split in half along the long-axis, and the extednt of plaque exposure was morked on the root surfaces with burs. The roots were either root-planed(Test group), or left uninstrumented(Control group), and transplanted in the extraction sockets with decalcified freeze-dried allografts filling the void. The flaps were sutured to cover the sockets completely. The animals were sacrificed after 12 weeks of healing, and the specimens were examined histologically. The results were as follows : 1. No signs of inflammation or disease activity were observed in either groups. 2. Replacement root resorption was observed in both groups. 3. More connective tissue attachments and less ankylosis were observed in the test groups compared to the control. 4. The unresorbed remains of DFDB particles were observed in both groups. 5. DFDB particles in the apical portion of the alveolar sockets were encased in newly-formed bone, while those in the coronal areas were seen encapsulated with connective tissue. 6. No significant difference was found between root-planed and uninstrumented roots relative to the healing and the bone fromation in the recipient extraction sockdets. From the present study, there seemed to be no significant benefits in root planing the transplanted roots or grafting the sockets with DFDB in order to curve the replacement resorption, although the root-planed roots showed more connective tissue attachments. There was also no significant benefits in root transplantation and DFDB for and enhanced healing and bone formation in alveolar extraction sockets.

• Journal of Periodontal and Implant Science
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• v.33 no.3
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• pp.533-542
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• 2003

The purpose of this study is to evaluate histologic result of bone substituting material on defects followed tooth extraction. We compare the histologic findings control, DFDBA, Bio-Oss(R), and $Regenafil^{TM}$, Briefly, mandibular premolar teeth were extracted available for bone filling. All alveolar sites were checked after extraction and thoroughly debrided with a dental curet to remove the periodontal ligament. Extraction sites were prepared dehiscence on buccal side 7mm height from alveolar crest. The graft materials were filled into the extraction socket and dehiscenc defects. The animals were sacrificed 12 weeks after implantation. Both treated and control mandibular sites were histologically evaluated with light microscopy. Histologic observation at 12 weeks revealed that control and experimental sites were healed uneventfully and directly apposed to new bone without any adverse tissue reaction. DFDBA and Bio-Ossn(R)sites maintain width of alveolar crest but were not fully resorbed. $Regenafil^{TM}$ sites also maintain width and particles were resorbed more than other graft materials. From this results, it was suggested that $Regenafil^{TM}$ is promising boen substituting materials maintaining the width of alveolar crest and height follewed tooth extraction.