• Journal of Embryo Transfer
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• v.29 no.4
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• pp.397-401
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• 2014

The boar sperm has more lipid droplets and specialty of seminal plasma compared with other species, causing difficulties of freezing sperm and decreases for the utilization of frozen semen into the artificial insemination. However, several studies reported significant results for the recovery of sperm motility and reproductive by addition of cryoprotectants and seminal plasma after thawing. This study was designed to investigate the effects of supplementation of trehalose or glycerol in the LEY (lactose and egg yolk in BTS) solution for the conventional freezing and vitrification process. Two boars aged 16 months were used to collect semen for 2 times in a week. The samples were allotted to 3 freezing solutions (LEY + glycerol 10.5% + OEP 1.5%, LEY + trehalose 1M + OEP 1.5%, and sucrose 1.5M + trehalose 1 M + OEP 1.5%) after centrifugation at 800 g for 10 minutes. Semen was equilibrated in freezing solutions for 10 minutes and injected into plastic straws with 2~3 air bubbles to minimize freezing damages. Vitrification was performed to locate sperm in 5 cm above $LN_2$ for 5 minutes, and the conventional freezing was conducted with an automatic freezer. Motility and survival rates were measured by CASA (Computer assisted sperm an alyzing system) and FITC (Fluorescein isothiocyanate), respectively after thawing semen at $50^{\circ}C$ for 12 seconds. The results were analyzed by ANOVA with STATVIEW statistical program. The vitrificatioin solution (LEY + 10.5% glycerol + 1.5% OEP) presented higher motility (20.9%) than other solutions while the solution (LEY + 1M trehalose + 1.5% OEP) showed the lowest (motility : 5.2%). However, survival rates of vitrified sperms detected by FITC showed 1~4% live sperms in almost of dead sperms at all vitrification solutions' groups, but survival rate of freezing solution of LEY + 1M trehalose + 1.5% OEP LEY and LEY + 10.5% glycerol + 1.5% OEP were showed 49%, and 79%, respectively. There were differences (P<0.05) survival rate of conventional freezing in LEY + 10.5% glycerol + 1.5% OEP and LEY + 1M trehalose + 1.5% OEP and the remaining showed no differences. The results suggested that vitrified boar semen was not enough to be utilized for the artificial insemination, but it showed possibility to utilize for ICSI and conventional freezing with glycerol would be useful method for artificial insemination in pig while we choose the outstanding semen against tolerance to freezing damages.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.10
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• pp.737-742
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• 2013

The purpose of this study was to remove sediments obtained from breeding ground using supersonics and micro-air flotation method. Sediments from Tongyong breeding grounds showed no contaminations of heavy metals but had great amount of organics. Thus, efficient removal of sediments was required to preserve water quality near breeding ground. Supersonics treatment for sediments was determined to be essential because higher removal efficiency of sediments was obtained when supersonics treatment was used. In addition, application of coagulants increased removal efficiency because its usage increased particle size of sediments, which enabled easy trapping of sediments particle into micro-air bubbles. Removal efficiency of sediments slightly decreased from 95.8% (1 g/L) to 83.9% (8 g/L) at the tests for different amount of sediments, but most of tiny particles were removed from water where sand size particles were left in the bottom of reactors.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.10
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• pp.710-716
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• 2013

New and renewable energy sources have drawn attention because of climate change. Many studies have been carried out in waste-to-energy field. Fast pyrolysis of waste lignocelluosic biomass is one of the waste-to-energy technologies. Bubbling fluidized bed (BFB) reactor is widely used for fast pyrolysis of the biomass. In BFB pyrolyzer, bubble behavior influences on the chemical reaction. Accordingly, in the present study, hydrodynamic characteristics and fast pyrolysis reaction of waste lignocellulosic biomass occurring in a BFB pyrolyzer are scrutinized. The computational fluid dynamics (CFD) simulation of the fast pyrolysis reactor is carried out by using Eulerian-Granular approach. And two-stage semi-global kinetics is applied for modeling the fast pyrolysis reaction of waste lignocellulosic biomass. To summarize, generation and ascendant motion of bubbles in the bed affect particle behavior. Thus biomass particles are well mixed with hot sand and consequent rapid heat transfer occurs from sand to biomass particles. As a result, primary reaction is observed throughout the bed. And reaction rate of tar formation is the highest. Consequently, tar accounts for 66wt.% of the product gas. However, secondary reaction occurs mostly in the freeboard. Therefore, it is considered that bubble behavior and particle motions hardly influences on the secondary reaction.

• Proceedings of the Korean Society of Rheology Conference
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• 2006.06a
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• pp.81-84
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• 2006

Slot coating process, in continuous and patch modes, has been applied for the many precise coating products, e.g., flat panel displays and second batteries. However, manufacturing uniform coating products is not a trivial task at high-speed operations because various flow instabilities or defects such as leaking, bubbles, ribbing, and rivulets are frequently observed in this process. It is no wonder, therefore, that many efforts to understand the various aspects of dynamics and coating windows of this process have been made both in academia and industry. In this study, as the first topic, flow dynamics within the coating bead in slot coating process has been investigated using the one-dimensional viscocapillary model by lubrication approximation and two-dimensional model by Flow-3D software. Especially, operability windows in both 1D and 2D cases with various slot die lip designs have been successfully portrayed. Also, effects of process conditions like viscosity and coating gap size on slot coating window have been analyzed. Also, some experiments to find minimum coating thickness and coating windows have been conducted using slot die coater implemented with flow visualization device, corroborating the numerical results. As the second topic, flow dynamics of both Newtonian and Non-Newtonian fluids in patch or pattern slot coating process, which is employed in manufacturing IT products such as secondary batteries, has been investigated for the purpose of optimal process designs. As a matter of fact, the flow control in this system is more difficult than in continuous case because od its transient or time-dependent nature. The internal die and die lip designs for patterned uniform coating products have been obtained by controlling flow behaviors of coating liquids issuing from slot. Numerical simulations have been performed using Fluent and Flow-3D packages. Flow behavior and pressure distribution inside the slot die has been compared with various die internal shapes and geometries. In the coating bead region, efforts to reduce irregular coating defects in head and tail parts of one patterned coating unit have been tried by changing die lip shapes. It has been concluded that optimal die internal design gas been developed, guaranteeing uniform velocity distribution of both Newtonian and shear thinning fluids at the die exit. And also optimal die lip design has been established, providing the longer uniform coating layer thickness within one coating unit.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.273-273
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• 2013

Recently, Point-of-care (POC) testing microdevices enable to do the patient monitoring, drug screening, pathogen detection in the outside of hospital. Immunochromatographic strip (ICS) is one of the diagnostic technologies which are widely applied to POC detection. Relatively low cost, simplicity to use, easy interpretations of the diagnostic results and high stability under any circumstances are representative advantages of POC diagnosis. It would provide colorimetric results more conveniently, if the genetic analysis microsystem incorporates the ICS as a detector part. In this work, we develop a reverse transcriptase-polymerase chain reaction (RT-PCR) microfluidic device integrated with a ROSGENE strip for colorimetric influenza H1N1 virus detection. The integrated RT-PCR- ROSGENE device is consist of four functional units which are a pneumatic micropump for sample loading, 2 ${\mu}L$ volume RT-PCR chamber for target gene amplification, a resistance temperature detector (RTD) electrode for temperature control, and a ROSGENE strip for target gene detection. The device was fabricated by combining four layers: First wafer is for RTD microfabrication, the second wafer is for PCR chamber at the bottom and micropump channel on the top, the third is the monolithic PDMS, and the fourth is the manifold for micropump operation. The RT-PCR was performed with subtype specific forward and reverse primers which were labeled with Texas-red, serving as a fluorescent hapten. A biotin-dUTP was used to insert biotin moieties in the PCR amplicons, during the RT-PCR. The RT-PCR amplicons were loaded in the sample application area, and they were conjugated with Au NP-labeled hapten-antibody. The test band embedded with streptavidins captures the biotin labeled amplicons and we can see violet colorimetric signals if the target gene was amplified with the control line. The off-chip RT-PCR amplicons of the influenza H1N1 virus were analyzed with a ROSGENE strip in comparison with an agarose gel electrophoresis. The intensities of test line was proportional to the template quantity and the detection sensitivity of the strip was better than that of the agarose gel. The test band of the ROSGENE strip could be observed with only 10 copies of a RNA template by the naked eyes. For the on-chip RT-PCR-ROSGENE experiments, a RT-PCR cocktail was injected into the chamber from the inlet reservoir to the waste outlet by the micro-pump actuation. After filling without bubbles inside the chamber, a RT-PCR thermal cycling was executed for 2 hours with all the microvalves closed to isolate the PCR chamber. After thermal cycling, the RT-PCR product was delivered to the attached ROSGENE strip through the outlet reservoir. After dropping 40 ${\mu}L$ of an eluant buffer at the end of the strip, the violet test line was detected as a H1N1 virus indicator, while the negative experiment only revealed a control line and while the positive experiment a control and a test line was appeared.

• Journal of Distribution Science
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• v.14 no.4
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• pp.103-110
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• 2016

Purpose - This study investigates the improvement of rationalization of distribution structure in Korean diamond market. It also explores the international distribution of diamond and how the distribution of Korean diamond market system was improved. This study also for providing the evaluation method in case of purchasing diamond on the consumers. Research Design, Data, and Methodology - The research investigates how international diamond distribution market has been changed since 1933 by De Beers. The international Diamond rough stone has been deregulated in supply and demand by Debeers since July, 2000, therefore, the price maintenance policy of diamond market also has been changed. In the short term, the diamond price in market has been down, whereas, in the long term, the market share of Debeers has affected the high quality of diamond price in world market. Before 1985, both G color and VVS1 clarity were used as the level of percentages in the diamond certificate of authenticity in Korea. But, after 1985, the diamond certificate of authenticity uses Diamond Grading Report. Results - Between the 1970's and 1980's, Debeers had controlled about 80 percentages of international diamond supply market. But, Debeers share in diamond market fell by 60 percentages in 2000's. Debeers supplied 31%(4390 carets) of international diamond supply and 41%(39 billion dollars) in 2003. However, Debeers shares 50% of market shares in the diamond supply market by Alosa in Russia. In Korea, the diamond grading report system has been used since 1985. But, the diamond grading report system has price bubbles and much irrational parts in grading system methods. Conclusions - 4C, the grading system of diamond, is a method for comparing and evaluating diamond objectively. Diamond is graded according to its color, cut, clarity, and carat. The price of diamond is determined based on its each item. Consumers purchase diamond for the purpose of investment and wearing. In terms of investment, it is recommended to purchase diamond with color of D grade, cut with Excellent or Very Good Cut grade, Clarity of FL or IF, and more than 3 carat. As for wearing purpose, it is highly recommended for diamond to have color of F or G grade, cut of Excellent or Very Good Cut, clarity of VS2 or SI1, and more than 1 carat Before 2000, Central Selling Organization(CSO) distributed about 80 percentages rough diamond to world market exclusively by purchase, classification, assessment, and sales. After 2000, Dbeers diamond company looses slowly market shares, while Almosa diamond company etc. in Russia are taking over world market shares more and more. Debeers market shares have been falling over the years, and the international diamond markets are gradually growing by other international diamond companies. But, there is no change in Korean diamond market after 1980's. Korean diamond distribution needs to follow international level of Diamond Grading System. By using different grading systems with different panel members, Korean diamond grading system needs to follow international perfect grading systems to grow diamond markets and maintain within top 10 diamond markets countries.

• Nuclear Engineering and Technology
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• v.52 no.12
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• pp.2860-2866
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• 2020

Oxide dispersion-strengthened materials W-1wt%Pr₂O₃ and W-1wt%La₂O₃ were synthesized by wet chemical method and spark plasma sintering. The field emission scanning electron microscopy (FE-SEM) analysis, XRD and Vickers microhardness measurements were conducted to characterize the samples. The irradiations were carried out with a 5 keV helium ion beam to fluences up to 5.0 × 10²¹ ions/m² under 600 ℃ using the low-energy ion irradiation system. Transmission electron microscopy (TEM) study was performed to investigate the microstructural evolution in W-1wt%Pr₂O₃ and W-1wt%La₂O₃. At 1.0 × 10²⁰ He⁺/m², the average loops size of the W-1wt%Pr₂O₃ was 4.3 nm, much lower than W-1wt% La₂O₃ of 8.5 nm. However, helium bubbles were not observed throughout in both doped W materials. The effects of pre-irradiation with 1.0 × 10²¹ He⁺/m² on trapping of injected deuterium in doped W was studied by thermal desorption spectrometry (TDS) technique using quadrupole mass spectrometer. Compared with the samples without He⁺ pre-irradiation, deuterium (D) retention of doped W materials increased after He⁺ irradiation, whose retention was unsaturated at the damage level of 1.0 × 10²²D₂⁺/m². The present results implied that irradiation effect of He⁺ ions must be taken into account to evaluate the deuterium retention in fusion material applications.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.649-656
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• 2019

Flux cored arc welding (FCAW), which is used widely in many fields, such as shipyards, bridge structures, construction machinery, and plant industry, is an alternative to shielded metal arc welding (SMAW). FCAW is used largely in the welding of carbon and alloy steel because it can be welded in all poses and obtain excellent quality in the field under a range of working conditions. In this study, the mechanical properties of welded parts were analyzed after different welding of SS400 and SM490A using FCAW. The following conclusions were drawn. The tensile test results satisfied the KS standard tensile strength in the range of 400~510 N/mm2 in all welding positions. The bending test confirmed that most of the specimens did not show surface breakage or other defects during bending and exhibited sufficient toughness, even after plastic deformation. The hardness test results were lower than the standard value of 350 Hv of KS B 0893. Similar to the hardness test, were greater than the KS reference value. The macro test revealed no internal flaws, non-metallic inclusions, bubbles or impurities on the entire cross section of the weld, and there were no concerns regarding lamination.

• The Journal of the Acoustical Society of Korea
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• v.38 no.4
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• pp.450-458
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• 2019

Passive cavitation imaging method is used to observe the ultrasonic waves generated when a group of bubbles collapses. A problem with passive cavitation imaging is a low resolution and large side lobe levels. Since ultrasound signals generated by passive cavitation take the form of a pulse, the amplitude distribution of signals received across the receive channels varies depending on the direction of incidence. Both the centroid and flatness were calculated to determine weights at imaging points in order to discriminate between the main and side lobe signals from the signal amplitude distribution of the received channel data and to reduce the side lobe levels. The centroid quantifies how the channel data are distributed across the receive channel, and the flatness measures the variance of the channel data. We applied the centroid weight and the flatness to the passive cavitation image constructed using the delay-and-sum focusing and minimum variance beamforming methods to improve the image quality. Using computer simulation and experiment, we show that the application of weighting in delay-and-sum and minimum variance beamforming reduces side lobe levels.

• Journal of the Korean earth science society
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• v.42 no.2
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• pp.185-194
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• 2021

A lava dome and sheet lava flow can be observed at the seashore of Aewol, Jeju island. The cylindrical lobes are characterized by a concentric structure consisting of a massive core and radial joints. Columnar joints with different thickness between the upper and lower parts are developed in the sheet lava flow around the rock salt field in Goeomri. The upper part of the columnar joints is uneven in shape, and has a diameter of 120-150 cm. The lower part of the columnar joints is hexagonal and pentagonal in shape, and has a diameter of about 60 cm. The cylindrical lobes can be divided into two groups based on size and shape. One is a megalobe, with a semicircular outline and a maximum diameter of 30 m. The other is a circular lobe with a diameter of less than 10 m. The columns in the radial joints have hexagonal and pentagonal cross sections and gradually increasing diameter, outward from the core, to a size of 80-120 cm at the rim. The concentric structure observed in the cylindrical lavas is attributable to a combination of four factors. The first is a circular crack caused by the decrease of the temperature and density difference between the inside and outside of the cylindrical lava flow. The second is a concentric chisel mark of the radial joints, which formed at the same time as the radial joints. The third is a flow band, which is a trace left in a round passage when lava flows through. The fourth is a vesicular band formed in a cave by gas bubbles escaping from the lava flow.