• Membrane Journal
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• v.15 no.2
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• pp.114-120
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• 2005

The purpose of this study is to obtain practical information about membrane coupled $ A_2O$ system for muncipal wastewater treatment. A flat-plate microfiltration (MF) module with a pore size $0.25\;{\mu}m$ was submerged into the aeration basin and treated water was filtrated through the membrane by continuous suction with low pressure. The system was operated with synthetic wastewater to find operational parameters of internal recycle ratio and maximum MLSS showing best water quality and long-term stability. The internal recycle was defined as type 1 for aerobic to anoxic tank and type 2 for anoxic to anaerobic tank, respectively When the flux was maintained at $0.015\;m^3/m^2/hr$ (15 LMH) with 2Q type 1 internal recycle ratio, the optimal operational setting were 10 internal recycle ratio for type 2 and maximum MLSS of 11,000 mg/L among tested conditions. At this condition, removal efficiencies of BOD, CODcr, T-N and T-P showed $97.3\%,\;94.2\%,\;64.0\%,\;63.0\%$, respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.6
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• pp.397-402
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• 2016

To produce adequate electricity in nuclear and thermal power plants, an optimal amount of steam should be supplied to a generator connected to high- and low-pressure steam turbines. A turbine output control device, which is a special steam valve employed to supply or interrupt the steam to the turbine, is operated using a hydraulic servo actuator. In power plants, the performance of servo actuators is degraded by the air generated from the hydraulic system, or causes frequent failures owing to an increase in the wear of the seal. This is due to the seal being burnt as generated heat using the produced compressed air. Some power plants have exhausted air using a fixed orifice, and thus they encounter power loss due to mass flow exhaust. Failures are generated in hydraulic pumps, electric motors, and valves, which are frequently operated. In this study, we perform modeling and analysis of the load-sensing air-exhaust valves, which can be passed through very fine flow under normal use conditions, and exhaust mass flow air at the beginning stage as with existing fixed orifices. Then, we propose a method to prevent failures due to the compressed air, and to ensure the control accuracy of hydraulic servo actuators.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.86-95
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• 2006

Brillouin backscatter is a type of reflection that occurs when light is shone into an optical fibre. Brillouin reflections are very sensitive to changes in the fibre arising from external effects, such as temperature, strain and pressure. We report here several case studies on the measurement of strain using Brillouin reflections. A mechanical bending test of an I beam, deployed with both fiber optic sensors and conventional strain gauge rosettes, was performed with the aim of evaluating: (1) the capability and technical limit of the DTSS technology for strain profile sensing; (2) the reliability of strain measurement using fiber optic sensor. The average values of strains obtained from both DTSS and strain gauges (corresponding to the deflection of I beam) showed a linear relationship and an excellent one-to-one match. A practical application of DTSS technology as an early warning system for land sliding or subsidence was examined through a field test at a hillside. Extremely strong, lightweight, rugged, survivable tight-buffered cables, designed for optimal strain transfer to the fibre, were used and clamped on the subsurface at a depth of about 50cm. It was proved that DTSS measurements could detect the exact position and the progress of strain changes induced by land sliding and subsidence. We also carried out the first ever distributed dynamic strain measurement (10Hz) on the Korean Train eXpress(KTX) railway track in Daejeon, Korea. The aim was to analyse the integrity of a section of track that had recently been repaired. The Sensornet DTSS was used to monitor this 85m section of track while a KTX train passed over. In the repaired section the strain increases to levels of 90 microstrain, whereas in the section of regular track the strain is in the region of 30-50 microstrain. The results were excellent since they demonstrate that the DTSS is able to measure small, dynamic changes in strain in rails during normal operating conditions. The current 10km range of the DTSS creates a potential to monitor the integrity of large lengths of track, and especially higher risk sections such as bridges, repaired track and areas at risk of subsidence.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.3
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• pp.207-214
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• 2012

This study was conducted to optimize the processing conditions, including the ingredient ratio and extraction time, for a water-soluble fraction of Alaska pollock head and non-forming sea tangle by response surface methodology. Our results indicated that the optimal independent variables for obtaining extracts with a high yield and desirable sensory characteristics were 1.32 for $X_1$ (extraction time), 1.36 for $X_2$ (sea tangle concentration) and 0.93 for $X_3$ (water volume) in coded values, and 5.48 h for $X_1$, 18.18% for $X_2$ and 6.86 times for $X_3$ in uncoded values. The predicted values of $Y_1$ (yield), $Y_2$ (TCA soluble-N) and $Y_3$ (overall acceptance) for extracts produced under these optimized conditions were 22.10%, 1.83 g/100 mL and 5.9, respectively, their experimental values were 21.4%, 1.7 g/100 mL and 5.7, respectively. No significant differences between the actual and predicted values were found.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.242-248
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• 2017

This study was conducted to develop a cylindrical paperpot manufacturing equipment which is capable of continuously producing paperpots with a constant size. The equipment consists of the soil supply part, the paper supply part, the pot manufacturing part, the paperpot cutting part and its process for manufacturing paperpot from the soil supply to the paperpot cutting is continuously performed. As a result of the performance test using this equipment, we suggest that the optimal moisture content and injection pressure to supply soil are 50%~60%, and 0.5 Mpa respectively. Moreover the appropriate temperature for adhesive strength is $150{\sim}160^{\circ}C$ taking into account the performance of device and adhesion time. Also, considering the cutting speed and safety, it is appropriate to adopt a straight blade having a clean plan at a minimum angle of $30^{\circ}$. In addition, the manufacturing capacity of the developed equipment was 3300 pots per hour.

• Korean Journal of Plant Resources
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• v.29 no.5
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• pp.525-531
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• 2016

Cynanchum wilfordii Radix (CWR), Arctium lappa L (ALL), and Dioscorea opposite (DO) have been known to improve blood lipid profile, blood pressure, and inflammation. To find the optimal combination ratio of CWR, ALL, and DO in terms of vascular health improvement, we compared the effects of various combinations on gene expression of Vascular cell adhesion protein 1 (VCAM-1) in human aortic smooth muscle cells (HASMC). VCAM-1 mediates endothelial leukocyte adhesion and is upregulated in atherosclerosis. Cells was stimulated by TNF-α (10 ng/㎖, 2h) and treated with various combinations for 24 h. A combination (CADM5, CWR:ALL:DO = 2:1:1) showed the strongest suppression of VCAM-1 so that CADM5 was chosen for further experiments. We performed cell viability test with CADM5 (0, 3.125, 12.5, 25, 50, and 100 ㎍/㎖) and no cytotoxicity was found. We also investigated the effect of CADM5 on protein expression of VCAM-1, ICAM-1, Nrf-2, and HO-1 using western blotting. We found that CADM5 diminished the expression of VCAM-1 and increased the expression of Nrf-2 and HO-1. Therefore, we concluded that CADM5 (CWR:ALL:DO = 2:1:1) effectively improves vascular health by regulating the expression of VCAM-1.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.361-368
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• 2004

We separated the multilayer structure of CD-R(compact disk-recordable) and investigated optimal spot marking conditions and physical and chemical transitions in response to various laser beam energh levels. Spot marking(80 ${\mu}{\textrm}{m}$ spot size) was produced on the surface of each layer using a Q-switched Nd:YAG laser between 27 mJ and 373mJ. By investigating resulting pit formation with Optical Microscopy(OM) and Optical Coherence Tomography(OCT), we analyzed the formation process of spot marking in the multilayer structure of different chemical composition. The localized heating of the substrate in the multilayer thin film caused the short temporal thermal expansion, and absorbed optical energy between reflective and dye interfaces melted dye and increased the volume. During the cooling phase, formation of pit and surrounding rim can be explained by three distinct processes; effect of surface tension, evaporation by spontaneous temperature increase due to laser energy, and mass flow from the recoil pressure. Our results shows that the spot marking formation process in the multilayer thin film is closely related to the layers' physical, chemical, and optical properties, such as surface tension, melt viscosity, layer thickness, and chemical composition.

• Fire Science and Engineering
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• v.16 no.3
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• pp.26-31
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• 2002

Bromotrifluoromethane(halon-1301) and bromochlorodifluoromethane(halon-1211) have been widely used as a clean fire extinguishing agents due to their outstanding properties. However, production and use of halon are currently being phased out under an international agreements Montreal Protocol because of global environmental concerns and HFCs have been considered as promising alter-natives for the replacement of halon since their ozone depletion potentials are low. The vapor-liquid equilibrium data are required as important basic information in evaluating the solubility of clean fire extinguishing agents and determining their optimal compositions. In this work, we chose HFCs such as HFC-22 HFC-125, and HFC-l34a for gaseous fire extinguishing agents and nitrogen as a pressurization gas for a proper jet velocity of these agents. Phase equilibria for binary mixtures of nitrogen/HFC-22, nitrogen/HFC-125, and nitrogen/HFC-l34a were measured in the temperature range from 283.15K to 303.15K. For equilibrium measurement, we used a circulation type apparatus in which both vapor and liquid phases were continuously recirculated. The experimental data were relatively well correlated with the Peng-Robinson equation of state with Wong-Sandier mixing rules.

• KSBB Journal
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• v.21 no.4
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• pp.312-316
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• 2006

A optimal condition for the Ginkgo biloba extraction in ethanol and water binary solvent system has been proposed based on concentration of bilobalide and ginkgolide known as having a antimicrobial components in the range 5% to 70% ethanol in water at $80^{\circ}C$. Concentration of bilobalide as a single component of Ginkgo biloba leaves extract is the highest at the 60% ethanol and ginkgolide A and B is highest at 50% ethanol. Antimicrobial effect of Ginkgo biloba leaves extracts on the S. aureus was also examined by disc diffusion test and optical density test. In case of the disc diffusion test, the clean zone diameter was increased from 0.95 cm to 1.70 cm as ethanol concentration increased from 5 to 70%. However, over the 40% of ethanol concentration the antimicrobial effect was almost flat. Based on these results, we propose that the 40% of ethanol and 60% water solvent is most desirable for Ginkgo biloba extract considering vapor pressure problem in concentrating process after extraction. We introduced SEM and TEM to figure out the morphological change on the surface and inside body of S. aureus when Ginkgo biloba leaves extract was treated. After mixed with Ginkgo biloba leaves extract blast like blebs appeared on the surface of S. aureus cells and cell wall was not observed. From the these results, it seems that the Ginkgo biloba leaves extract including bilobalide and ginkgolide A, B prevent cell wall synthesis.

• Journal of Yeungnam Medical Science
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• v.11 no.1
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• pp.55-62
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• 1994

The use of intraoperative application of Mitomycin C at the filtration site has been known to improve the surgical outcome in glaucomatous eyes with high risk for failure of trabeculectomy. The author performed trabeculectomies with intraoperative Mitomycin C on 25 eyes of 20 patients with poor surgical prognosis to study the efficacy and safety of this technique in glaucomatous patients with high risk for failure of trabeculectomy. After the preparation of a scleral flap, 0.2mg/ml solution of Mitomycin C was applied between Tenon's capsule and the sclera for 2 minutes. The exposed area was then irrigated with 200 ml of balanced salt solution. The follow-up period was from 1 to 7 months (mean 3.8 months). The mean preoperative intraocular pressure (IOP) was $38.6{\pm}6.6mmHg$. The mean final postoperative IOP was $11.7{\pm}3.8mmHg$. Twenty three (88%) of the 25 eyes were successfully controlled with the IOP of less than or equal to 20 mmHg without glaucoma medication. There were early postoperative complications of hyphema in 5 eyes (20%), shallow anterior chamber in 4 eyes(16%), punctate keratopathy in 3 eyes (12%), aqueous leaking from conjunctival wound in 2 eyes (8%), encapsulated bleb in 1 eye (4%) and choroidal detachment in 1 eye (4%), and 4 eyes had long term hypotony lasting more than 2 months. Although Mitomycin C is simple to use and effective adjunct to trabeculectomy, further study will be needed to determine the mechanism of action, indication, dosage and optimal exposure time of Mitomycin C.