• 제목/요약/키워드: Coagulation

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Experimental and Numerical Study of Aerosol Coagulation by Gravitation (에어로졸 입자의 중력응집에 관한 실험 및 수치적 연구)

  • 권순박;이규원
    • Journal of Korean Society for Atmospheric Environment
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    • v.16 no.1
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    • pp.1-10
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    • 2000
  • The behavior of aerosos due to gravitational coagulation was studied experimentally and numerically. In experimental study, the geometric mean particel size increased as time elapsed in a vertical tube column, while the size decreased when the tube was set horizontally. The particle size distribution was observed to maintain the lognormal form during the coagulation process. Separately, numerical calculations were performed for studying the aerosol behavior under gravitational and Brownian coagulation using the moment method. By comparing the expeimented results with the numerical predictions, the governing mechanism of the aerosol behavior proved to be gravitational coagulation.

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Studies on the On-line Dry-let Wet Spinning of Polyacrylonitrile(IV) -Effect of Coagulation and Annealing Conditions on the Fiber Properties- (아크릴고분자의 온-라인건습식방사공정에 관한 연구(IV)-응고 및 연신조건이 섬유물성에 미치는 영향-)

  • 김병철;민병길
    • Textile Science and Engineering
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    • v.32 no.6
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    • pp.570-575
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    • 1995
  • The effect of coagulation and annealing conditions on the physical properties of fiber in the on-line dry-jet wet spinning of PAN was investigated. Over the coagulation conditions observed, the crystalline structure was not effected by coagulant composition and coagulation temperature. The degree of crystallinity was nearly independent of coagulant composition, but lowering the coagulation temperature lowered it. The stretchability of as-spun fibers was decreased with increasing the coagulation temperature. The PAN fibers had values of degree of orientation higher than 90% regardless of the coagulation temperature if stretched to a maximum drawing ratio. The density of fiber was increased with increasing draw ratio. The higher coagulation temperature and the higher water content in the coagulation bath were more favorable to produce PAN fiber with better mechanical properties.

Effect of Ozonation and Coagulation on NOM Molecular Distribution and Activated Carbon Adsorption Capacity (응집과 오존처리가 NOM 분자량 분포특성과 활성탄 흡착능에 미치는 영향)

  • Kim, Sung Jin;Hong, Seong-Ho
    • Journal of Korean Society of Water and Wastewater
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    • v.19 no.4
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    • pp.480-486
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    • 2005
  • The main goals of this work are to investigate the effect of molecular weight distribution(MWD) and activated carbon adsorption capacity after conventional coagulation and enhanced coagulation. The ozonation was very effective to decompose the NOM to smaller size and to remove molecular smaller than 1,000. The concentration of DOC was reduced 0.25mg/L and 0.56mg/L by the conventional coagulation and the enhanced coagulation, respectively The conventional coagulation was not effective to remove NOM. However, the enhanced coagulation was effective to remove MW bigger than 10,000. The higher MW was shifted to smaller weight by ozonation in the raw water and the after conventional coagulation. After enhanced coagulation the MW had not changed significantly by ozonation. Also, it was observed that the ozone dosage did not have significant impact on MW shifting to smaller size. The adsorption capacity simulated by IAST comparing K values showed that the adsorption capacity was not impacted by ozone doses. There was very strong correlation between MW smaller than 10,000 and the mid- and strongly adsorbable fractions.

Effect of residual metal salt on reverse osmosis membrane by coagulation-UF pretreatment process (응집-UF 전처리 공정에 의한 잔류 금속염이 역삼투막에 미치는 영향)

  • Go, Gilhyun;Kim, Suhyun;Kang, Limseok
    • Journal of Korean Society of Water and Wastewater
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    • v.33 no.6
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    • pp.413-420
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    • 2019
  • Pretreatment system of desalination process using seawater reverse osmosis(SWRO) membrane is the most critical step in order to prevent membrane fouling. One of the methods is coagulation-UF membrane process. Coagulation-UF membrane systems have been shown to be very efficient in removing turbidity and non-soluble and colloidal organics contained in the source water for SWRO pretreatment. Ferric salt coagulants are commonly applied in coagulation-UF process for pretreatment of SWRO process. But aluminum salts have not been applied in coagulation-UF pretreatment of SWRO process due to the SWRO membrane fouling by residual aluminum. This study was carried out to see the effect of residual matal salt on SWRO membrane followed by coagulation-UF pretreatment process. Experimental results showed that increased residual aluminum salts by coagulation-UF pretreatment process by using alum lead to the decreased SWRO membrane salt rejection and flux. As the salt rejection and flux of SWRO membrane decreased, the concentration of silica and residual aluminum decreased. However, when adjusting coagulation pH for coagulation-UF pretreatment process, the residual aluminum salt concentration was decreased and SWRO membrane flux was increased.

Treatment of Phosphorus Species using Iron Coagulation and Fenton Oxidation (철염 응집과 펜톤 산화를 이용한 인의 존재형태별 처리)

  • Park, Sung-Hwan;Moon, Byung-Hyun
    • Journal of Korean Society on Water Environment
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    • v.30 no.6
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    • pp.653-657
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    • 2014
  • Effects of $H_2O_2$ addition for fenton oxidation on iron coagulation for treatment of phosphorus species, such as orthophosphate, metaphosphate, pyrophosphate, organic phosphate, were investigated. The effects of coagulant dosage, hydrogen peroxide dosage and the combined sequence ferric coagulation and $H_2O_2$ addition for fenton oxidation and coagulation were studied. The characteristics of floc growth rate were monitored using the PDA. The removal efficiencies of phosphorus species by iron coagulation were increased as Fe/P molar ratio increased. However, the removal efficiencies of metaphosphate, pyrophosphate, organic phosphate by a ferric coagulation were not increased as Fe/P molar ratio increased. The removal efficiency of metaphosphate, pyrophosphate, organic phosphate was increased by using iron coagulation and $H_2O_2$ addition for fenton oxidation. The result indicated that non-reactive phosphorus after iron coagulation was changed to reactive phosphorus by $H_2O_2$ addition for fenton oxidation and the oxidized iron enhanced the coagulation efficiencies.

Manufacture of Precheese Powder by Use of Low-temperature Renneting Made from Raw Milk Using Spray Dryer

  • An, Shuo-Feng;Piao, Jing-Zhu;Chang, Oun-Ki
    • Food Science of Animal Resources
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    • v.30 no.4
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    • pp.551-559
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    • 2010
  • Among the food constituents, proteins differ in coagulation properties as compared to other constituents in food system. Especially milk protein coagulate through different pathways thus this coagulability can be used for manufacture of various dairy products or as a determinant of dairy product analysis. These milk coagulation methods include organic solvent, isoelectric point, trichloroacetic acid, Ca-sensitive casein, heavy metal ion and rennet coagulation. The coagulation experiment was performed using above parameters at $0^{\circ}C$ and $25^{\circ}C$ to find the dehydration conditions before coagulating for precheese powder making. After different chemical treatments, there was no coagulation at $0^{\circ}C$ rather at $25^{\circ}C$ whatever the mode of coagulation methods was. The appearance of precipitate with coagulation methods was quite different from above mentioned methods of coagulation illustrated by scanning electron microscope. These powders were used for fabrication of camembert cheese by renneting coagulation at $0^{\circ}C$, showing the possibility of cheese materials and of food additives for fabrication of products.

A Case of Heel Reconstruction with a Reverse Sural Artery Flap in a Hemophilia B Patient

  • Lee, Byung-Kwon;Shim, Jeong-Su
    • Archives of Plastic Surgery
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    • v.39 no.2
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    • pp.150-153
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    • 2012
  • Hemophilia B is a rare blood coagulation disorder. Complications such as bleeding and hematoma can cause necrosis of flaps, wound disruption, and the disturbance of wound healing. In particular, guidelines for flap operations in hemophilia B patients have still not been defined, and case reports are rare. We reconstructed the heel of a 41-year-old male hemophilia B patient using a reverse sural artery flap operation. The patient presented with mild hemophilia, having 27% of the normal value of coagulation factor IX. Coagulation and the changing value of the coagulation factor were regularly measured, and 70% of the normal value of coagulation factor IX was maintained through the injection of recombinant coagulation factors and antihemorrhagics. Hematoma developed twice (postoperative day [POD] 5 and POD 7) and in each case the hematoma was removed. Injections of recombinant coagulation factors and antihemorrhagics were continuously administered until postoperative week 2. When the coagulation factors were within normal ranges. In this article, a hemophilia B patient underwent reverse sural artery flap surgery and the healing progress was analyzed. We conclude that higher than baseline levels of coagulation factors are needed for successful healing in reverse sural artery flap surgery.

Comparison of Electrocoagulation and Chemical Coagulation in Removal on Water Treatment (정수처리에서 전기응집과 화학응집의 처리효율 비교)

  • Han, Moo-Young;Song, Jae-Min;Park, Sang-Cheol
    • Journal of Korean Society of Water and Wastewater
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    • v.18 no.5
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    • pp.689-695
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    • 2004
  • Electrocoagulation has been suggested as a promising alternative to conventional coagulation. The process is characterized by reduced sludge production, no requirement for chemical use, and ease of operation. However, this coagulation has scarcely been studied in water purifying process. This study was performed several batch experiments to compare turbidity removal between electrocoagulation and chemical coagulation. In addition, characteristics of floe were evaluated with zeta potential and particle size distributions. Electrocoagulation showed a relatively higher removal of turbidity (approximately 5%) with the same aluminum amount than conventional chemical coagulation. In addition, turbidity removal by electrocoagulation was less sensitive to pH and was greater for more extensive pH range than chemical coagulation. The results of zeta potential and floc size distributions illustrated that electrocoagulation provided the preferable conditions for coagulation such as zeta potential close to zero millivolt and increased portions of particles in the range of 40 and $100{\mu}m$.

Introduction to Coagulation System (혈액응고 기전에 대한 고찰)

  • Lyu, Chuhl-Joo
    • Neonatal Medicine
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    • v.18 no.1
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    • pp.1-5
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    • 2011
  • Coagulation involves the regulated sequence of proteolytic activation of a series of proteins to achieve appropriate and timely hemostasis in an injured vessel. In the non-pathological state, the inciting event involves exposure of circulating factor VIIa to extravascularly expressed tissue factor, which brings into motion the series of steps which results in cell based model of coagulation. In the new concepts of coagulation system, initiation, amplification and propagation steps are involved to converse of fibrinogen to fibrin. The precisely synchronized cascade of events is counter-balanced by a system of anticoagulant mechanisms. Developmental hemostasis refers to the age-related changes in the coagulation system that are most marked during neonate and childhood. An understanding of these changes in crucial to the accurate diagnosis of hemostatic abnormalities in neonate and children. This review aims to elucidate the main events within the coagulation cascade as it is currently understood to operate in vivo, and also a short review of the anticoagulants as they relate to this model. Also this paper describes the common pitfalls observed in the clinical data related to the coagulation system in neonate to children.

Effects of dolomite addition on phosphorus removal by chemical coagulation of secondary treated effluent (백운석 첨가가 응집에 의한 하수 처리수의 인 제거에 미치는 영향)

  • Lee, Byung-Ha;Park, Joon-Hong;Cha, Ho-Young;Maeng, Sung-Kyu;Song, Kyung-Guen
    • Journal of Korean Society of Water and Wastewater
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    • v.26 no.3
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    • pp.443-451
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    • 2012
  • Wastewater treatment plants need to reduce phosphorus in order to meet increasingly stringent regulations on phosphorus. This study evaluated the feasibility of dolomite as a coagulation aid to enhance phosphorus removal from secondary treated wastewater by chemical coagulation. Standard jar tests were conducted to evaluate the effect of dolomite addition on a coagulation process for phosphorus removal and to determine the optimum doses of coagulants and dolomite. Coagulants used with dolomite yielded a significant improvement in phosphorus removal and reduced total phosphorus concentrations below 0.02 mg/L in wastewater effluent. Dolomite has played an important role in enhancing phosphate adsorption and increasing pH, as a coagulation aid. The maximum removal efficiency of phosphorus in this study was yielded at 25 mg/l of dolomite and 20 mg Al/L of PAC dose. However, considering economic aspects, the optimum doses of dolomite and PAC were 10 mg/L and 15mg Al/L, respectively. Consequently, dolomite, a coagulation aid, can be used in coagulation processes to enhance the removal of phosphorus.