Dissolved Air Flotation(DAF) 접촉조의 수리동력학적 조건이 입자의 제거에 미치는 영향

유제선,김성훈,신은허,박희경 대한상하수도학회 2003 상하수도학회지 Vol.17 No.1

Hydrodynamic conditions for optimum solids capture within the contact zone, which are governed by the geometry and flow, are not yet well understood. In this research, dimensionless parameters which represent hydrodynamic conditions in the contact zone were derived, using the Buckingham π theorem. Those parameters are Reynolds No. (Re), Froude No. (Fr), Weber No. (We), Local Weber No., and Bubble Capacity No. (Bc). The particle removal rate was investigated by changing each value of the dimensionless parameters. The experimental results indicate that particle removal rate, when gravity dominates and the flow is semi-turbulent (Fr < 0.3, Re < 8000), is higher than when inertia dominates and flow is turbulent. For the We, higher removal rates were obtained in the range of the We < 40. Relative to the Local We, smaller bubbles which are influenced more by surface tension than inertia, demonstrated a higher particle removal rate than larger bubbles. For the Bc, the optimal range is from 0.3 to 0.5. We suggest that these dimensionless parameters can be used to diagnose the performance of and to design a DAF reactor.

벽체의 뒷채움이 제한되어 있는 경우의 토압산정이론식

유범식,김훈제 안성산업대학교 1996 論文集 Vol.28 No.-

In case that the length of Backfill behind wall is confined, the active earth pressure acting wall will be reduced as compare with that calculated by conventional active earth pressure theories. Consequently, in this research , the theoritical formula of active earth pressure is proposed and conclusions are following. The angle of failure plane, 'α' of backfill soil is inclined to reduce as 'B/H' increase regardless of the angle of internal friction of backfill soil and earth pressure increase as the angle of internal friction reduce. The reduction effect of active earth pressure according to backfill length increase as 'B/H' more reduce than 'B/H=0.6'.

전산유체 기법을 이용한 DAF 부상조에서의 수리 특성 고찰

김성훈,유제선,김영미,박희경 대한상하수도학회 2002 상하수도학회지 Vol.16 No.4

Dissolved air flotation is a solid-liquid separation process that uses fine rising bubbles to remove particles in water. DAF is found most effective in treating algae and lower density flocs that are hard to remove in sedimentation process. Some researcher reports the results of an experimental study which examined the flow within the flotation zone of a DAF tank (ONeill at al., 1997). I would be concluded that, in general, the flow within flotation zone is robust and that differences in the performance of individual DAF tanks must be the result of processes occurring within the contact zones of these tank, not as the result of flotation processes. In this research, the authors thought that the efficiency of the DAF process is strongly related to bubble size. It means bubble rising velocity at the air injection nozzle is most important factor of DAF process. However, bubble movement in DAF tank is somewhat complicate, so it is hard to make up conceptual model through simple mass balance as other researchers did (Leppinen at. al., 2000). For the modeling of turbulent 2-phase flow in the tank, the standard k-ε model was used in CFD code because it is widely accepted and the coefficients for the model are well established. This model uses the eddy-viscosity hypothesis for the turbulence. As the result of this study, the authors concluded that bubble size and its rising velocity is very important factor of DAF process and the recycle ratio must be also consider for the flotation zone parameter. Also, For the improved model, relation between turbulent intensity and bubble-particle attachment must be studied.

전산유체 기법을 이용한 용존공기부상법에서의 접촉도 조건변화에 따른 충돌효율평가

김성훈,유제선,박희경 대한상하수도학회 2004 상하수도학회지 Vol.18 No.2

Dissolved air flotation (DAF) is a solid-liquid separation process that uses fine rising bubbles to remove particles in water. Most of particle-bubble collision occurs in the DAF contact zone. This initial contact considered by the researchers to play a important role for DAF performance. It is hard to make up conceptual model through simple mass balance for estimating collision efficiency in the contact zone because coupled behavior of the solid-liquid-gas phase in DAF system is 90 complicate. In this study, 2-phase(gas-liquid) flow equations for the conservation of mass, momentum and turbulence quantities were solved using an Eulerian-Eulerian approach based on the assumption that very small particle is applied in the DAF system. For the modeling of turbulent 2-phase flow in the reactor, the standard k-ε mode Ⅰ(liquid phase) and zero-equation(gas phase) were used in CFD code because it is widely accepted and the coefficients for the model are well established. Particle-bubble collision efficiency was calculated using predicted turbulent energy dissipation rate and gas volume fraction. As the result of this study, the authors concluded that bubble size and recycle ratio play important role for flow pattern change in the reactor. Predicted collision efficiency using CFD showed good agreement with measured removal efficiency in the contact zone. Also, simulation results indicated that collision efficiency at 15% recycle ratio is higher than that of 10% and showed increasing tendency of the collision efficiency according to the decrease of the bubble size.

9-12%Cr강의 첨가원소 및 열처리에 따른 미세조직거동과 경도변화

주성욱,유정훈,신기삼,허성강,이재현,석진익,김병훈,김정태 국립7개대학공동논문집간행위원회 2004 공업기술연구 Vol.4 No.-

9-12%Cr steel are getting increasing attention for expanded application as high temperature materials applicable for gas turbine compressors, steam turbine rotors, blade and casing. For efficient and extensive application of 9-12%Cr steel, the data in addition to the improvement of mechanical properties on the correlation of microstructural evolution and mechanical properties are inevitable and thus the investigation in this study is performed for the determination for the specimens heat-treated at 600, 650 and 700℃ for 1000, 3000 and 5000hrs. The microstructure of as-received specimen was tempered martensite, with a high dislocation density and secondary phases. Upon high temperature heat-treatment, the martensite lath got larger and dislocation density decreased resulting the reduction of the strength. In addition, sharp growth of secondary phases was observed in the specimen heat-treated at 700℃ for 5000hrs. A specimen aged at 600℃ and 650℃ Laves phase was observed. The hardness showed close relationship with the secondary phase particle and dislocation density.

Linkage Structure Analysis of Barley and Oat β-Glucans by High Performance Anion Exchange Chromatography

Je-Hoon Ryu,Dong-Hyung Yoo,Byung-Hoo Lee,Suyong Lee,Mi Hyun Joo,Sang-Ho Yoo 한국식품과학회 2009 Food Science and Biotechnology Vol.18 No.1

Cereal β-glucans, linked essentially by mixed β-(1,4/1,3) glycosidic bonds, were extracted, purified, and structurally identified. Previously chemical structure of barley β-glucans was characterized from 3 varieties of ‘Gang’, ‘Ohl’, and ‘Gwangan’, and the (1,4)/(1,3) linkage ratio of the β-glucans was identical. In this study, β-glucans from 1 barley (‘Chal’) and 3 oat (‘Ohl’, ‘Samhan’, and ‘Donghan’) varieties were structurally scrutinized, and the linkage pattern of total 7 cereal β-glucans was compared. The amount of 2 major 3-O-β-cellobiosyl-D-glucose (DP3) and 3-O-β-cellotriosyl-D-glucose (DP4) from barley and oat accounted for only 66.6-73.3 and 68.12-81.89% of water-extractable β-glucan fractions, and the (1,4)/(1,3) linkage ratios of both barley and oat β-glucans were within very narrow range of 2.27-2.31 and 2.38-2.39, respectively, among the cultivars tested. Structural difference in the cereal β-glucans was evident when DP3:DP4 ratio in the β-glucan structure was compared. As a result, this ratio was significantly greater for barley β-glucan (2.26-2.74) than for oat (1.54-1.66). Chal-B had the greatest DP3 to DP4 ratio among the samples, which in turn reflected the least amount of (1,4)-linkages.

Identification of apolipoproteinA1 reduction in the polycystic kidney by proteomics analysis of the Mxi1-deficient mouse

Yoo, Kyung Hyun,Kim, Yo Na,Lee, Min Joo,Seong, Je Kyung,Park, Jong Hoon WILEY-VCH Verlag 2009 Proteomics Vol.9 No.15

<P>Autosomal dominant polycystic kidney disease is one of the most common human monogenic diseases in which extensive epithelial-lined cysts develop in kidney and other organs. Affected kidneys are not only characterized by the formation of cysts, but also by changes associated with the extracellular matrix and interstitial inflammation, which can progress to fibrosis and loss of renal function. Mxi1 protein, which is a c-myc antagonist, may be essential in controlling cellular growth and differentiation. Previously, multiple tubular cysts were observed in kidney of Mxi1-deficient mice aged 6 months and more. Presently, 2-DE and MALDI-TOF MS was employed to identify the differentially expressed proteins in the kidney. Several proteins were identified, among them, apolipoproteinA1 which is a major component of the high-density lipoprotein complex and has anti-inflammation effects, was significantly decreased in the Mxi1-deficient mouse. We confirm the development of inflammation and renal fibrosis and the expression of extracellular matrix molecules including transforming growth factor were also increased in cystic kidney. These results indicate that expression of proteins related with inflammation and renal fibrosis changes by Mxi1 inactivation in polycystic kidney.</P>

Development of Kompetitive Allele Specific PCR Markers for Submergence Tolerant Gene Sub1 in Rice

( Je-hoon Moon ),( Daniel Son ),( Jung-woo Lee ),( Soo-cheul Yoo ) 한국육종학회 2019 Plant Breeding and Biotechnology Vol.7 No.1

The SUBMERGENCE 1 (SUB1) locus, conferring tolerance to complete inundation, was identified, and gel-based DNA markers, AEX1 and GnS2, were previously developed for marker-assisted breeding (MAB). However, a high throughput and high specific method, at low cost, is still required to detect Sub1 alleles. Kompetitive Allele Specific PCR (KASP) markers enable high throughput analysis for a large number of seeds, as well as detection of both alleles, in a single reaction. In this study, we developed KASP markers that can distinguish specific alleles at Sub1A loci based on single nucleotide polymorphisms (SNPs). Marker validations were carried out by genotyping of a segregating population with the developed KASP markers. The results from KASP assay and gel-based marker analysis were consistent for Sub1A alleles. KASP markers developed for Sub1A would be helpful due to high accuracy, low cost, and a high throughput genotyping feature in MAB.

Treadmill exercise is associated with reduction of reactive microgliosis and pro-inflammatory cytokine levels in the hippocampus of type 2 diabetic rats.

Yoo, Dae Young,Chae, Junghyun,Jung, Hyo Young,Yim, Hee Sun,Kim, Jong Whi,Nam, Sung Min,Kim, Dae Won,Choi, Jung Hoon,Seong, Je Kyung,Yoon, Yeo Sung,Hwang, In Koo Butterworths [etc.] 2015 Neurological research Vol.37 No.8

<P>In the present study, we investigated the effects of treadmill exercise on microglial activation and the subsequent release of tumour necrosis factor-alpha (TNF-alpha), interleukin (IL)-6 and IL-1-beta in the hippocampus in a rat model of type 2 diabetes.</P>

Roof Structure Design and Evaluation for Improvement of Roof Strength of Three-Wheel Vehicles

Yoo, Je Sung,Kwon, Jun Beom,Huh, Hoon Trans Tech Publications, Ltd. 2014 Key Engineering Materials Vol.626 No.-

<P>This paper is concerned with auto-body frames and roof structures against rollover motion which could take place frequently with TWVs compared to FWVs because of the major difference of the loading between the two motions. Topology optimization is utilized for conceptual design and preliminary design of the roof structure for various loading conditions. The roof structure for TWV consists of existing part of FWV and a new part called Cross-bar reinforcement. Although a test method for regulation of roof strength is with static loading, simulations are carried out for both static and dynamic cases. In the dynamic loading case, rate-dependency of a material needs to be considered for accurate results of FE analysis.</P>