• Journal of Sensor Science and Technology
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• v.8 no.4
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• pp.320-326
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• 1999

A small cartridge, with a nozzle system for washing off the dirt from the surfaces of sensing gates, was fabricated. The proposed nozzle structure was designed for cartridge by using the simulation tool of fluid (CFD-ACE). Whole size of the fabricated cartridge by using micromachining techniques is about $2.6\;cm{\times}1.5\;cm$, the size of the washing nozzle is $0.2\;mm{\times}0.6\;mm$ and its dead volume is only about $20\;{\mu}l$. A micro-reference electrode was achieved by employing a differential system with ISFETs/QRE (quasi-reference electrode)/REFET (reference field-effect transistor). Metal electrodes was deposited at both ends of blowing channel were used to check the presence of bubble in the microchannel. The pH-ISFET was inserted into the fabricated cartridge and the washing effect of the nozzle system in cartridge was invested.

• Polymer(Korea)
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• v.26 no.4
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• pp.477-482
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• 2002

In order to control the micro-pore structure of glassy carbon (GC), an activation agent of KOH was introduced as the glassy carbon was prepared from phenolic resin with a curing agent of phosphoric acid. The yield and properties of GC were investigated as a function of KOH content. Although the GC produced without KOH had nonporous structure except the trace of bubble formation, the GC with KOH had very porous structure. The surface area of GC with KOH increased continuously up to 870 $m^2$/g with the increase of KOH content. The carbonization yield and apparent density measured in water reduced from 40 to 15% and iron 1.5 to 0.9 g/$cm^3$, respectively, and the electrical resistivity increased from $50{\times}10^{-4}$ to $60{\times}10^{-4}$$\Omega$.cm with the increase of KOH content.

• Journal of the Korean Ceramic Society
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• v.53 no.6
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• pp.604-609
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• 2016

This study reports on wet-foam stability with respect to porous ceramics from a particle-stabilized colloidal suspension that is achieved through the addition of polymethyl methacrylate (PMMA) using a wet process. To stabilize the wet foam, an initial colloidal suspension of $Al_2O_3$ was partially hydrophobized by the surfactant propyl gallate (2 wt.%) and $SiO_2$ was added as a stabilizer. The influence of the PMMA content on the bubble size, pore size, and pore distribution in terms of the contact angle, surface tension, adsorption free energy, and Laplace pressure are described in this paper. The results show a wet-foam stability of more than 83%, which corresponds to a particle free energy of $2.7{\times}10^{-12}J$ and a pressure difference of 61.1 mPa for colloidal particles with 20 wt.% of PMMA beads. It was possible to control the uniform distribution of the open/closed pores by increasing the PMMA content and by adding thick struts, leading to the achievement of a higher-stability wet foam for use in porous ceramics.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.6
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• pp.389-393
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• 2000

High-quality $Er^{3+}$ doped Mg : $LiNbO_3$single crystal fibers were grown by a micro-pulling down ($\mu$-PD) method. Single crystal fibers were pulled down through the nozzle, at a pulling down rate of 0.5 mm/min and using a Pt crucible with a nozzle 1 mm in diameter in air atmosphere. Defects such as bubbles, cracks and inclusions were not detected in any of the grown crystals. The optical transmission of Er : Mg : $LiNbO_3$crystal was measured and the energy levels of $Er_2O_3$ ion could be calculated. The photoluminescence spectrum of crystal fibers showed an energy band emission with the strongest line corresponding to the $^4I_{3/2}{\to}^4I_{15/2}$transition. The concentration dependence of the entire wavelength region emission intensity upon excitation intensity measured emission intensity for the 3 mol% MgO doped fibers was larger than that for the 1, 5 mol% MgO doped fibers.

• Journal of KIISE
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• v.42 no.7
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• pp.910-918
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• 2015

This paper presents a parameter visualization technique to overcome the limitation of the naked eye in contrast-enhanced ultrasonography. A method is also proposed to compensate for the distortion and noise in ultrasound image sequences. Meaningful parameters for diagnosing liver disease can be extracted from the dynamic patterns of the contrast enhancement in ultrasound images. The visualization technique can provide more accurate information by generating a parametric image from the dynamic data. Respiratory motions and noise from micro-bubble in ultrasound data may cause a degradation of the reliability of the diagnostic parameters. A multi-stage algorithm for respiratory motion tracking and an image enhancement technique based on the Markov Random Field are proposed. The usefulness of the proposed methods is empirically discussed through experiments by using a set of clinical data.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.4_2
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• pp.637-644
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• 2022

In this study, the flow characteristics according to the shape of the vortex nozzle was studied by numerical analysis and the amount of microbubble generation was measured experimentally. The shape of the vortex nozzle is cylindrical, diffuser, and conical type. The axial fluid velocity in the induced tube gradually increased from the inlet to the outlet. In particular, the fluid velocity in the nozzle part increased rapidly. The velocity distribution of the fluid at the inlet of the induced tube showed that the flow rotates counterclockwise in the outer region and the inner center of the induced tube. At the outlet of the induced tube, the cylindrical and conical type showed rotational flow, and the diffuser type showed irregular turbulent flow. The dimensionless pressure ratio 𝜂 of the inner region of the induced tube was lower than that of the outer region. Also, 𝜂 near the outlet of the induced tube in cylindrical and conical type showed a similar tendency to the inlet area. At the outer region of inlet of induced tube, intense vorticity was observed on the wall and in lower region. At the inner region of inlet of induced tube, intense vorticity was observed on the inner wall of the induced tube and in the central region of the inlet of the induced tube. At the outlet of induced tube, in the case of the cylindrical and conical type, intense vorticity was observed near the inner wall, the diffuser type showed irregular strong vorticity inside the tube. The total number of bubbles measured was the most in the cylindrical type, and the microbubbles less than 50mm occurred the most in the conical type.

• Journal of Wetlands Research
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• v.25 no.4
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• pp.291-296
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• 2023

DIWS system was employed to treat hydrochloric acid gas from cold rolling mill process of iron and steel industry. Chlorine gas generated from the acid regeneration system was combined with hydrogen gas and hydrogen chloride gas was increased to 50%. After the injection of Na₂S₂O₃ to remove chlorine gas, the removal of hydrogen chloride was stably kept 87.5~88.8%, where the inflow was 13.1~13.4ppm and the outflow was 1.5~1.7ppm. DIWS system can be recommended for the real iron and steel plant because it was stably maintained not only the air emission standards but also the reduction of chemical usage.

• Journal of Society of Preventive Korean Medicine
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• v.12 no.2
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• pp.13-25
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• 2008

The purpose of this study was to investigate extract from mixed culture with Trichloloma matsutake mycelium in oriental medicine and cereal medium(OCM) to develop new material for pharmaceutical products and medicinal food for diabetes mellitus. To evaluate of hypoglycemic activity of OCM extracts, we examined the inhibitory activity of ${\alpha}$-glucosidasein OCM, blood glucose level and liver function of streptozotocin(STZ) induced diabetic rat. Experimental group was divided into 6 groups: first, it was divided into normal control group(hereafter NC group) and diabetes-induced group, and diabetes-induced group was subdivided into diabetic control group(DC group), treated by hot water extracts group(HE), ultra sonic waves, micro waves, and micro bubble extracts g roup(UE), crude polysaccharide of HE group (HEE) and crude polysaccharide of UE group(UEE) at a dose of 300mg/kg/body weight, respectively. In diabetic-induced groups, after streptozotocin was melted in 0.01M citrate buffer at 50mg/kg/body weight, when the non-fasting blood glucose levelwas 300 mg/dl or more in blood collected from the tail vein, it was regarded as diabetic induction and then such diabetic-induced experimental animals were used in this experiment. At the end of the experiment, blood glucose level increased by 4.19% in DC group but significantly decreased by 32.34%, 19.19%, 17.81% and 17.64%, respectively in UEEE, UE, HE, and HEE groups. In the cases of AST, ALT, and ALP, the experiment group treated with extracts showed significantly lowerblood glucose level than DC group. The levels of BUN and uric acid were found to be lower in the UMPM extract group(UE) than HW extract group(HE), which implies that herb medicine medium extracts in which Tricholoma matsutake mycelia were cultured are effective in reducing impaired liver function as well as high blood glucose level caused by diabetes. In addition, the administration of low temperature UMPM extracts was found to produce better results than that of high temperature hot water extracts. In this regard, it is expected that extracts from herb medicine obtained by cultivating Tricholoma matsutake mycelia will be widely used as new ingredients for foods and medicines for prevention and treatment of diabetes.

• Microbiology and Biotechnology Letters
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• v.29 no.4
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• pp.240-247
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• 2001

The effect of microsparged aeration in mammalian cell bioreactor on the oxygen transfer rate and cell viability was studied. The microspargers with differ- ent micron-sized pores were used to supply oxygen to the medium. The oxygen transfer coefficients (k$_{L}$a) measured in the bioreactor were markedly increased, which is due to the increase of the contacting area between air bubbles and liquid medium when the pore size of microsparger decreases. When the impellers of two different types (square-pitch marine impeller and $45^{\circ}$ pitched flat blade impeller) were used for agitation, the k$_{L}$a values were slightly higher with the marine impeller than with the blade impeller. The detrimental effect of direct gas sparging with microsparger on mammalian cells was investigated in bubble columns with various air flow rates and different pore sized microspargers. The first-order cell death rate constant ($k_{d}$ /7) was shown to be directly proportional to the air flow rate and inversely proportional to the pore size. During the cultivation of hybridoma cells using microsparger with the pore size of $0.57\mu$m in the mammalian cell culture bioreactor, the continuous sparging caused the cell death and suppressed the cell growth. However, cells grew normally and cell viability was maintained above 90% in the logarithmic phase when the air was intermittently sparked in order to maintain the dissolved oxygen level above 20%.

• Journal of Navigation and Port Research
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• v.40 no.4
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• pp.173-181
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• 2016

From 2016, controls on reduction of NOx and SOx emissions from the vessels that are operated in the emission control area were tightened. The selectivity catalytic reduction system of the denitrification equipment which NOx among the above controlled materials is very effective and used commercially very much. But it has the disadvantage that CSR is activated at high temperatures. Therefore, the SCR and SCR activation instrument that can react even at low temperatures by using micro-nano bubbles so that the above problems can be minimized were developed. And the computational fluid dynamics technique was used by ANSYS-CFX package to prepare the plan that improves the SCR system's efficiency. Simulation for the viscous flow analysis of the SCR system was executed by applying the Navier-Stokes equation to it as a governing equation. For the SCR system's shape, 3D modeling was done by using CATIA V5. SCR jet nozzle's position was checked by changing it to the intervals of 1/3, 1/2, and 2/3 from the inlet of the vent pipe to compare the SCR system's efficiency. And the number of nozzles was compared and analyzed by simulating 4, 6, and 8 holes to check an effect of the number on the SCR system's efficiency. The simulation result has found that the closer nozzles are to the inlet of the vent pipe and the more nozzles are, the more efficiency is improved.