• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.5
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• pp.299-310
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• 2009

Fuel cells are expected to be promising future power sources in both aspects of thermal efficiency and environmental friendliness. Accordingly, worldwide research and development efforts have been enormously increasing recently in various applications such as power plants, transportation and portable power sources. Among others, high temperature fuel cells, such as solid oxide fuel cells and molten carbonate fuel cells, are suitable for electric power plants. Moreover, their high operating temperature is quite appropriate to construct further advanced integrated systems. This paper reviews recent literatures on research and development of integrated power generation systems based on high temperature fuel cells. Research and development efforts are summarized in the area of fuel cell/ gas turbine hybrid systems, application of carbon capture technology to fuel cell systems, integration of coal gasification with fuel cells, and the use of alternative fuels.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.10
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• pp.1465-1469
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• 2001

A sensitive high-performance liquid chromatographic method was developed to determine the content of cholesterol in milk and dairy products. To optimize separation of cholesterol, mobile phases including acetonitrile:2-propanol (8:1, v/v), acetonitrile:methanol (3:1, v/v), and acetonitrile:methanoI:2-propanol (7:3: I, v/v/v) were compared. Acetonitrile/methanol/2-propanol was superior to the other mobile phase systems for separating cholesterol. Liquid-liquid extraction (LLE) of cholesterol was simplified using a non-polar solvent, hexane, to remove interfering compounds, and had an excellent recovery $(100{\pm}1.0%)$ of cholesterol. A solid phase extraction (SPE) method using Sep-pak $C_{18}$ was developed and compared with LLE. The SPE method was rapid and highly reproducible. Both extraction methods were useful when used in combination with saponification of esterified cholesterol to facilitate total cholesterol determination. The detection limit of cholesterol was $0.01{\mu}g$. The newly developed HPLC method was rapid, simple, and accurate, and has advantages over the many methods commonly used.

• KSBB Journal
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• v.23 no.2
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• pp.169-176
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• 2008

The concentration of fresh gel from Aloe vera L. by using ulfrafiltration (UF) process was investigated and analyzed. The two membranes (organic and ceramic) with different molecular weight cut-off (MWCO) and modules (flat sheet and tubular) was used. Under optimum operation conditions, ceramic (zirconium dioxide) tubular membrane with MWCO of 50 kDa resulted in higher flux, less fouling, more turbid, higher total solid, higher polysaccharide and less aloin content. Optimum operation conditions were transmembrane pressure of 1.0 bar, feed velocity of 240 L/hr and temperature of $23^{\circ}C$. Volume concentration factor of aloe gel was 3.13 at permeate flux of $51.1\;L/m^2{\cdot}hr$ after processing time of 1.66 hr. Aloin in fresh aloe gel by UF process was effectively removed as permeate and bioactive polysaccharide content was 2.1 times higher than that of fresh aloe gel. These results allowed a very good level of concentration degree and polysaccharide content. Thus, ultrafiltration process of this study was suitable for the concentration of fresh aloe gel though the aloe concentrate showed both the viscosity decrease and partially separation of liquid layer during storage at $4^{\circ}C$.

• Korean Chemical Engineering Research
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• v.43 no.6
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• pp.696-703
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• 2005

The definition of cake is not established for cake filtration, and especially the definition was impossible for the filtration of the floc already sedimented. The definition is proposed with the experimental method named 'filtration-permeation'. The limit of water content which can be achieved with cake filtration of floc was established with the definition of cake. The expression operation of which the purpose is to reduce the water content of pre-formed filter cake is calculated with our 'unified theory on solid-liquid separation' and compared with the experimental results. The importance of expression is analyzed by the calculated whole procedure of cake filtration and expression. The method determining the most effective operational conditions of filter press including the cake discharge and washing time is proposed.

• Tribology and Lubricants
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• v.28 no.6
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• pp.278-282
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• 2012

Various bearings such as deep-groove ball bearings, angular-contact ball bearings, and roller bearings are used to support the load and to lubricate between the shaft and the housing. The bearings of potential rolling systems in a turbo pump are the deep-groove ball bearings as comparing with the bearings with rolling elements such as cylindrical rollers, tapered cylindrical rollers, and needle rollers. The deep-groove ball bearings consist of rolling elements, an inner raceway, an outer raceway and a retainer that maintain separation and help to lubricate the rolling element that is rotating in the raceways. In the case of water-lubricated ball bearings, however, fluid friction between the ball and raceways is affected by the entry direction of flow, rotation speed, and flow rate. In addition, this friction is the key factor affecting the bearing life cycles and reliability. In this paper, the characteristics of flow conditions corresponding to a deep-groove ball bearing are investigated numerically, with particular focus on the friction distribution on the rolling element, in order to extend the analysis to the area that experiences solid friction. A simple analysis model of fluid flow inside the water-lubricated ball bearing is analyzed with CFD, and the flow characteristics at high rotation speeds are presented.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.2
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• pp.251-259
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• 2015

The main objective of this research is to study feasibility for applying metal membrane to remove particles from air scouring membrane backwash water. Also, the research was conducted to investigate the influence of polyamine coagulation on floc growth in membrane backwash water as pretreatment for removal particles. From the results of experiments for evaluating the influence of polyamine coagulation on floc growth, it was investigated that particles in the rage of $2{\sim}50{\mu}m$ grew up to $30{\sim}5,000{\mu}m$. In addition, all six metal membranes showed lower removal efficiency, which was 0.87~13.89%, in the case of no polyamine coagulant. On the other hand, in the case of injecting polyamine coagulant, those did extremely high efficiency in 56~92%. From the SEM(Scanning Electron Microscope) images of filtered wiremesh and metal foam membrane, sieve effects were predominant for liquid solid separation in wiremesh and adsorption and diffusion capture effects were predominant in metal foam membrane.

• Journal of Animal Environmental Science
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• v.19 no.2
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• pp.169-176
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• 2013

This survey was conducted to investigate the present conditions of operational management in the 45 animal manure public resource center (APRC) in Korea. The regional distribution, processing capacity per year, capacity of liquid fertilizer storage tank, solid-liquid separation, utilization of facilities, odor reduction facility, on-site odor strength, complained in the community, liquid fertilizer sprayed area, use the Agrix, land application recipe, composting degree, quality management and general grading were surveyed and evaluated. General grading was divided with 5 stages (very good, good, fair, lack and bad). The number of evaluated "very good" animal manure public resource center was 7, and "good" was 5 and more than "fair" was 27. However, the number of evaluated negatively including "lack" and "bad" was occupied as 40% of the 45 animal manure public resource center.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.4
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• pp.404-412
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• 2017

A centrifugal cyclone dust collecting apparatus includes a hydro cyclone dust collecting apparatus for separating solid or liquid using liquid or suspension as a medium. In this study, the formation mechanism and improvement of air core and inner air layer were confirmed through Particle Image Velocimetry. These results showed that the modified experimental model was designed in the conventional method suitable for the separation of juvenile fish and eggs. The inlet speed of the multi-stage hydrocyclone dust collector, which can increase the inlet velocity and minimize floatage in the turbulence chamber, was increased from 0.15 to 0.30 m/s. As a result, the air core was stably formed, the inner air layer was increased with increasing speed. In addition, the dust collecting efficiency of egg and juvenile fish was 97.8% on average, It can infer that this system confirmed the ability to efficiently collect particles of $40{\mu}m$ or more.

• Applied Chemistry for Engineering
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• v.17 no.6
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• pp.565-574
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• 2006

The trend towards the application of single enantiomers of chiral compounds is undoubtedly increasing. Among the various methods to obtain one single enantio-riched compound selectively, enantioselective catalysis is the most attractive method. Especially, it is important to increase the activity, selectivity and lifetime of usually expensive chiral catalysts with a minute quantity in the enantioselective synthesis. Immobilization of active homogeneous catalysts is a fashionable topic in asymmetric catalysis, providing the inherent advantage of easy separation and better handling properties. Many different ways have been investigated to improve the enantioselectivity of products and to recycle the catalysts. This review mainly focused on the present scope and limitations of different types of enantioselective heterogeneous catalysts.

• Archives of Pharmacal Research
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• v.26 no.2
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• pp.120-123
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• 2003

A method for the determination of terbutaline enantiomers in human urine by capillary elctrophoresis has been developed. Optimum resolution was achieved using 50 mM phosphate buffer, pH 2.5, containing 15 mM of hydroxypropyl-$\beta$-cyclodextrin as a chiral selector. Urine samples were prepared by solid-phase extraction with Sep-pak silica, followed by CE. The assay was linear between 2-250 ng/mL (R = 0.9998 for (S)-(+)-terbutaline and R = 0.9999 for (R)-(-)-terbutaline) and detection limit was 0.8 ng/mL. The intra-day variation ranged between 6.3 and 14.5% in relation to the measured concentration and the inter-day variation was 8.2-20.1%. It has been applied to the determination of (S)-(+)-terbutaline and (R)-(-)-terbutaline in urine from healthy volunteer dosed with racemic terbutaline sulfate.