• The Korean Journal of Ecology
• /
• v.19 no.6
• /
• pp.543-562
• /
• 1996

Zooplankton community structure and the factors correlated with community differences were examined in sandusky Bay (SB) and the open water of Lake Erie (LE, U.S.A.). SB zooplankton communities differed from those in LE by having a greater rotifer density and species richness. Keratella spp., Brachionus spp., and Pompholyx complanata dominated SB rotifers; Brachionus and Pompholyx were rarely seen in LE. Of 19 rotifer species observed, nine species were found only at SB sites. Ordination of zooplankton species abundance by detrended correspondence analysis (DCA) showed an overlap between SB and LE sites, but indicated a portion of the space that was occupied by only SB communities. The seasonal trajectories of zooplankton dynamics in the ordination space at SB sites differed from that of LE. The zooplankton most important in forcing site separation along a DCA Axis I at SB sites were Brachionus angularis, Pompholyx complanata, Keratella valga, Keratella quadrata, Filinia terminalis (rotifers), and Eubosmina coregoni and Daphnia (cladocerans). These species had axis scores which were significantly correlated (p<0.01) with bacterial density and bacterial phosphorus, total phosphorus, and algal density. Very high baterial density and very abundant bacterivorous rotifers in SB suggest that the transport of bacterial carbon through rotifers may be a relatively important link to higher trophic leaels. We believe that this "microbial carbon flow" from the base of the food web may be important in determining the suitability of SB as a spawning site and nursery for larval and juvenile fish.nile fish.

• Journal of Hydrogen and New Energy
• /
• v.19 no.6
• /
• pp.490-497
• /
• 2008

For continuous operation of the sulfur-iodine(SI) thermochemical cycle, which is expected practical method for massive hydrogen production, suggesting operation conditions at steady state is very important. Especially, in the Bunsen reaction section, the Bunsen reaction as well as side reactions is occurring simultaneously. Therefore, we studied on the relation between the variation of compositions in product solution and side reactions. The experiments for Bunsen reaction were carried out in the temperature range, from 268 to 353 K, and in the $I_2/H_2O$ molar ratio of $0.094{\sim}0.297$ under a continuous flow of $SO_2$ gas. As the result, sulfur formed predominantly with increasing temperature and decreasing $I_2/H_2O$ molar ratios. The molar ratios of $H_2O/H_2SO_4$ and $HI/H_2SO_4$ in global system were decreased as the more side reaction occurred. A side reactions did not appear at $I_2/H_2O$ molar ratios, saturated with $I_2$, irrespective of the temperature change. We concluded that it caused by the increasing stability of an $I_{2x}H^+$ complex and a steric hindrance with increasing $I_2/HI$ molar ratios.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.54 no.5
• /
• pp.227-231
• /
• 2005

We have developed a microsystem with a capillary electrophoresis (CE) and an electrochemical detector (ECD). The microfabricated CE-ECD systems are adequate for a disposable type and the characteristics are optimized for an application to the electrochemical detection. The system was realized with polydimethylsiloxane (PDMS)-glass chip and indium tin oxide electrode. The injection and separation channels (80 um wide$\ast$40 um deep) were produced by moulding a PDMS against a microfabricated master with relatively simple and inexpensive methods. A CE-ECD systems were fabricated on the same substrate with the same fabrication procedure. The surface of PDMS layer and ITO-coated glass layer was treated with UV-Ozone to improve bonding strength and to enhance the effect of electroosmotic flow. For comparing the performance of the ITO electrodes with the gold electrodes, gold electrode microchip was fabricated with the same dimension. The running buffer was prepared by 10 mM 2-(N-morpholino)ethanesulfonic acid (MES) titrated to PH 6.5 using 0.1 N NaOH. We measured olectropherograms for the testing analytes consisted of catechol and dopamine with the different concentrations of 1 mM and 0.1 mM, respectively. The measured current peaks of dopamine and catechol are proportional to their concentrations. For comparing the performance of the ITO electrodes with the gold electrodes, electropherograms was measured for CE-ECD device with gold electrodes under the same conditions. Except for the base current level, the performances including sensitivity, stability, and resolution of CE-ECD microchip with ITO electrode are almost the same compared with gold electrode CE-ECD device. The disposable CE/ECD system showed similar results with the previously reported expensive system in the limit of detection and peak skew. When we are using disposable microchips, it is possible to avoid polishing electrode and reconditioning.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.16 no.3
• /
• pp.16-23
• /
• 2017

For most machine tools, it is necessary to remove chips and coolant oil because it they will continue to be created during the manufacture of workpieces. Existing products that are in use are installed and used as they reflect depending on the characteristics of each device separately. This study proposes a method to remove the security chip as well as developing an integrated system capable of reducing coolant damage. The Leverage AutoCAD and CATIA program was used for 2D and 3D design, shapes were identified by utilizing the KeyShot program, and the load and displacement analysis of the development apparatus was performed utilizing the ANSYS program. After the prototype underwent sufficient design review, the mixed oil separation device had a complete sensor control program using the LabVIEW program. The chip design process for transferring experiments and experiments on the mixed oil cooling device were developed for performance tests of the product. The final product resulted in an increase in space utilization during commercialization, reduced installation costs, and caused social effects such as pulmonary flow reduction, which, through the economic costs, reduces pollution, resulting in various benefits to the industry, such as deceased errors in the workplace decreases.

• Herbal Formula Science
• /
• v.21 no.1
• /
• pp.71-79
• /
• 2013

Objectives : Yijin-tang has been used in the treatment of gastrointestinal diseases such as irritable bowel syndrome, gastritis, and gastric ulcer. In this study, a high-performance liquid chromatography (HPLC) method was established for simultaneous analysis of six compounds, liquiritin, glycyrrhizin, hesperidin, 6-gingerol, homogentisic acid, and 3,4-dihydroxybenzaldehyde in Yijin-tang, a traditional Korean herbal medicinal preparation. Methods : A Gemini C18 column was used for the separation of six constituents at $40^{\circ}C$. The mobile phase using gradient elution consist of two solvent systems, 1.0% acetic acid in water (A) and 1.0% acetic acid in acetonitrile (B). The flow-rate was 1.0 mL/min and injection volume was $10{\mu}g$. The detector was a photodiode array (PDA) detector set at 254 nm and 280 nm. Results : The calibration curves of six compounds showed good linearity in various concentration ranges ($R^2{\geq}0.9997$). The limits of detection (LOD) and limits of quantification (LOQ) were 0.028-$0.192{\mu}g/mL$ and 0.093-$0.540{\mu}g/mL$, respectively. The RSD (%) of the intra and inter day validations were 0.03-0.84% and 0.05 -1.00%, respectively. Recovery was 96.14-01.90% and RSD (%) was less than 1.5%. Conclusions : The established simultaneous analysis methods will help management to improve the quality of Yijin-tang.

• Applied Chemistry for Engineering
• /
• v.5 no.1
• /
• pp.127-138
• /
• 1994

In the process of pervaporation separation for aqueous ethanol solution through cellulose tai-acetate(CTA) membrane, the modelling on the solution-diffusion permeation mechanism was built up on the basis of sorption and permeation experimental results. Also its function type and parameter were examined. The composition of sorption equilibrium in three component system(Ethanol/Water/CTA) were compared with the calculated value by Flory-Huggins' equation using the pure component sorption data. In order to apply the thermodynamic equilibrium relationship between the membrane free composition in the membrane and the equilibrium composition in the liquid phase, the apparent activity this system, however, the results were not satisfied. Diffusion equations were expressed with the concentration gradient considering permeate alone, and a concentration-dependent diffusion coefficient which includes a parameter was used. And this model was fitted with the measured permeation rates. If the permeation rate and the amount of sorption of one component were much larger than those of the other, the bulk flow term could not be negligible. The flux and selectivity were increased with increasing temperature, and with decreasing downstream pressure.

• Journal of Ocean Engineering and Technology
• /
• v.27 no.4
• /
• pp.76-82
• /
• 2013

Motion reduction of an offshore structure at resonant frequency is essential for avoiding critical damage to the topside and mooring system. A damping plate has a distinct advantage in reducing the motion of a floating structure by increasing the added mass and the damping coefficient. In this study, the heave motion responses of a circular cylinder with an impermeable and a permeable damping plate attached at the bottom of the cylinder were investigated thru a model test. The viscous damping coefficients for various combinations of porosity were obtained from a free-decay test by determining the ratio between any pair of successive amplitudes. Maximum energy dissipation occurred at a porous plate with a porosity P = 0.1008. Experimental results for regular and irregular waves were compared with an analytical solution by Cho (2011). The measured heave RAO and spectrum reasonably followed the trends of the predicted values. A significant motion reduction at resonant frequency was pronounced and the heaving-motion energy calculated by the integration of the area under the heave motion spectrum was reduced by more than 75% by the damping plate. However, additional energy dissipation by eddies of strong vorticity and flow separation inside a porous damping plate was not found in the present experiments.

• Journal of computational fluids engineering
• /
• v.20 no.4
• /
• pp.81-92
• /
• 2015

Construction waste mainly consists of concrete aggregates of various size. Improper handling of concrete waste would be a major environmental problem whereas its recycling would be both economically useful and environmentally friendly. Bigger concrete aggregates are crushed and converted to medium and fine particles to make them recyclable. An apparatus to separate the concrete aggregates by their size is thus needed for their effective recycling. In this work, segregation of concrete particles in air flows from a newly designed rotary separator having three stages of blades is simulated using a commercial software, ANSYS-CFX. Both 2-D and 3-D models with 360, 240 and 180 blades in each stage are considered. Fundamental mechanism of separation of particles(pase) and the effect of design parameters such as particle size, rotor speed, air flow rate etc. on the performance of the separator are investigated. Critical size of particles that can be separated by the developed separator is also presented in this work. Simulation results are overall in good agreement with data predicted from the theoretical model previously reported in the companion paper.

• Journal of computational fluids engineering
• /
• v.20 no.4
• /
• pp.70-80
• /
• 2015

Construction waste is known to include a large part of coarse and fine aggregates, which can be recirculated in the industry. Separating those aggregates economically from the waste has been thus considered to be one of the most important issues in this field. In particular, paste mixed in the waste causes significant complain from the inhabitants living near the place where waste-processing equipments are built and operated. In this study, we investigate the operational principle of a newly developed paste separator by using theoretical (in this first part) and CFD (in the second part) analysis. The separator consists of a rotor which turned out to play a significant role in separating those pastes from the aggregates. Under suitable assumptions regarding the air flow velocity as well as the particle velocity, we show that particles can be stagnant at the outlet of the roto channel for a wide range of parameter values, which allow the particles to get enough time to settle down via the gravitation. We also demonstrate such phenomenon by using a simple numerical simulation.

• The Korea Journal of Herbology
• /
• v.23 no.4
• /
• pp.45-49
• /
• 2008

Objectives: To investigate the quantitative determination of marker constituents of Dioscoreae Rhizoma by the packaging methods Methods: HPLC for the determinations of allatoin in the Dioscoreae Rhizoma. the separation method was performed on an Luna $NH_2$ column($250mm{\times}4.6mm,\;5{\mu}m$, Phenomenes) using solvent water-acetonitrile(2:8, v/v%) with photo diode array detector(210nm). The flow rate was 2.0 mL/min. Results: Retention time of allatoin in HPLC chromatogram was about 4.8 min and calibration curve showed good linearity($R^2$=0.9994) at concentrations from 50.0 to 1000.0 ${\mu}g/mL$ of allantoin. Average content of allantoin by packaging methods was $0.16{\sim}0.40%$. In addition. weight loss rate(%) of Dioscoreae Rhizoma according to the packaging methods was $-0.60{\sim}1.80%$. Conclusions: The variation on content of the marker constituent of Dioscoreae Rhizoma by the packaging methods didn't show difference.