• Korean Journal of Ecology and Environment
• /
• v.54 no.3
• /
• pp.199-208
• /
• 2021

Environmental DNA (eDNA) metabarcoding is effective method with high detection sensitivity for evaluating fish biodiversity and detecting endangered fish from natural water samples. We compared the richness of operational taxonomic units(OTUs) and composition of freshwater fishes according to filters(cellulose nitrate filter vs. glass fiber filter), extraction kits(DNeasy2^® Blood & Tissue Kit vs. DNeasy2^® PowerWater Kit), primer sets (12S rDNA vs. 16S rDNA), and PCR methods (conventional PCR vs. touchdown PCR) to determine the optimal conditions for metabarcoding analysis of Korean freshwater fish. The glass fiber filter and DNeasy2^® Blood & Tissue Kit combination showed the highest number of freshwater fish OTUs in both 12S and 16S rDNA. Among the four types, the primer sets only showed statistically significant difference in the average number of OTUs in class Actinopterygii (non-parametric Wilcoxon signed ranks test, p=0.005). However, there was no difference in the average number of OTUs in freshwater fish. The species composition also showed significant difference according to primer sets (PERMANOVA, Pseudo-F=6.9489, p=0.006), but no differences were observed in the other three types. The non-metric multidimensional scaling (NMDS) results revealed that species composition clustered together according to primer sets based on similarity of 65%; 16S rDNA primer set was mainly attributed to endangered species such as Microphysogobio koreensis and Pseudogobio brevicorpus. In contrast, the 12S rDNA primer set was mainly attributed to common species such as Zacco platypus and Coreoperca herzi. This study provides essential information on species diversity analysis using metabarcoding for environmental water samples obtained from rivers in Korea.

• Journal of Veterinary Clinics
• /
• v.24 no.4
• /
• pp.577-583
• /
• 2007

It is important to obtain semen with good quality for efficient fertilization and pregnancy. To obtain these semen, various methods have been developed but most of these methods are time consuming and require costly equipment. Therefore, the objective of this research is to investigate the usability of column filtration system as quick and simple method to get sperm with better quality. Ejaculates were obtained from 5 dogs and analyzed with basic quality parameters before each filtration. Sperm concentration was adjusted to $5{\times}10^7/ml$ after dilution. The experimental groups were divided into non-filtered group(control) and filtered groups(glass wool, Sephadex 5% and Sephadex 20%). Ejaculates were filtered through each filter system and assessed by recovery rate of sperm, motility, normal morphology, CFDA/PI stain and plasma membrane integrity(hypo-osmotic swelling test, HOST). The lowest recovery rate of spermatozoa was recorded in glass wool filtration group, followed by 20% Sephadex filtration group(p<0.05). There was no significant difference between control(non-filtered) and 5% Sephadex filtration poop. Also, there was no significant difference of sperm motility assessed under light microscope among experimental groups. Morphological normality of canine spermatozoa was the highest in the glass wool filtration group and the lowest in the 5% Sephadex filtration group with no significant differences versus 20% Sephadex filtration and control group, respectively(p<0.05). Viability of canine sperm assessed by CFCA/PI staining was the highest in the glass wool filtration poop with no significant difference versus the control group, and the lowest in the 20% Sephadex filtration group with no significant difference versus 5% Sephadex filtration group, respectively(p<0.05). HOS values of canine sperm was the highest in the 20% Sephadex filtration group with no significant difference versus 5% Sephadex filtration group, and the lowest in the control poop with no significant difference versus glass wool filtration group, respectively(p<0.05). Therefore, these results indicated that filtration treatment for extended canine sperm would be useful method to get sperm with better quality by trapping the damaged sperm, consequently filter would be physical barrier against injured or immotile sperm.

• Tribology and Lubricants
• /
• v.35 no.2
• /
• pp.106-113
• /
• 2019

We investigated the application of tetrahedral amorphous carbon (ta-C) coatings to fabricate a glass lens manufactured using a glass molding process (GMP). In this work, ta-C coatings with different thickness (50, 100, 150 and 200 nm) were deposited on a tungsten carbide (WC-Co) mold using the X-bend filter of a filtered cathode vacuum arc. The effects of thickness on mechanical and tribological properties of the coating were studied. These ta-C coatings were characterized by atomic force microscopy, scanning electron microscopy, nano-indentation measurements, Raman spectrometry, Rockwell-C tests, scratch tests and ball on disc tribometer tests. The nano-indentation measurements showed that hardness increased with an increase in coating thickness. In addition, the G-peak position in the Raman spectra analysis was right shifted from 1520 to $1586cm^{-1}$, indicating that the $sp^3$ content increased with increasing thickness of ta-C coatings. The scratch test showed that, compared to other coatings, the 100-nm-thick ta-C coating displayed excellent adhesion strength without delamination. The friction test was carried out in a nitrogen environment using a ball-on-disk tribometer. The 100-nm-thick ta-C coating showed a low friction coefficient of 0.078. When this coating was applied to a GMP, the life time, i.e., shot counts, dramatically increased up to 2,500 counts, in comparison with Ir-Re coating.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.22 no.4
• /
• pp.635-642
• /
• 2013

We have prepared a DEMO conveyor device for conveying a large 8G class glass sheet using ahorizontal air-cushion system. This device consists of the body frame and the driving frame that are combined to realize a frame for conveying glass without any contact.The driving frame comprises an air flotation table (bed), drive roller supported at both ends, and ASU. Part of the ASU serves to control the airflow as the chamber consists of a porous pad and fan. Fiber filters replace the porous pad and axial fans serve as an air compressor. In addition, to determine the appropriate glass levitation from the air table, this study examined the design specifications of the applied filter (discharge speed of HEPA and ULPA filters, and flow rate) as well as the height of the and the proper supporting roller height (14mm). Then, after adjusting the position of the ASU and the number of ASUs required to configure the UNIT air floating C/V, we analyzed the height and flatness of the glass and derived the appropriate layout (1140-mm distance between ASUs).

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.1
• /
• pp.6-11
• /
• 2009

Flow field in a roller conveyor system, induced from the movement of a cassette in which glasses for flat panel display are loaded, is numerically studied in this paper. Contamination on the glass surface by dust particles produced from mechanical friction between roller and cassette is predicted from the analysis results of flow fields. Results show that a large swirl flow is formed under the moving cassette with constant speed. This swirl flow is confined only under the cassette because two main streams from the backward and the fan filter unit on the top ceiling are sufficiently strong. Therefore, it can be said that possibility of the contamination by the particles originated from the friction is relatively low. It is also revealed that flow direction between glass plates is changed according to the speed of the cassette movement due to the shear force of glass plates.

• Journal of Environmental Health Sciences
• /
• v.22 no.2
• /
• pp.32-42
• /
• 1996

This study was performed to evaluate accuracy and precision of filter method and impinger method for analyzin airborne isocyanates in mixture (2, 6-TDI, HDI, 2, 4-TDI, MDI). Filter method was performed using the OSHA Method 42 and impinger method using the NIOSH Method 5521. The samples were analyzed by high performance liquid chromatography-ultraviolet detector (HPLC-UVD). After the optimum operating conditions for each method were investigated, samples with various concentration levels were quantified at the conditions. The precision was expressed by the pooled coefficient of variation(C.V.) and the accuracy by overall accuracy. The results are summarized as follows: 1. The optimum condition of filter method was determined at 35/65 ACN/buffer (0.01 M ammonium acetate) in mobile phase. And in case of impinger method, it was at 30/70 ACN/buffer(0.2 M sodium acetate). The effect of concentrations of acetate on the separation of the peaks was not significant, but, the effect of ACN/buffer ratio was significant. 2. The correlation coefficients for the two methods were above 0.9 in all isocyanate compounds. Average recovery efficiencies for 2, 6-TDI, HDI, 2, 4-TDI and MDI in filter method were 92.4%, 102.6%, 87.3% and 101.0%, respectively. Those in impinger method were 106.6%, 106.7%, 99.0% and 103.6%, respectively. As a result, the recovery efficiency of impinger method was higher than those of filter method in analyzing isocyanate compounds. 3. The pooled coefficients of variations of the methods were slightly higher than expected. The overall accuracies of the methods were within $\pm 25%$ for each isocyanate compound. Since these results satisfy NIOSH criteria, the accuracy of the experiment is appropriate. 4. As seen above, impinger method is more efficient than filter method. But, there are many disadvantages in impinger method. Therefore, solid sorbent such as a glass fiber filter must be developed in order to have the high efficiency not less than that of impinger method in the future.

• Korean Journal of Optics and Photonics
• /
• v.17 no.3
• /
• pp.285-289
• /
• 2006

A novel alignment-free micro-optic MZI filter has been demonstrated. The filter is composed of two fiber-pigtailed collimators and a beam-splittingplate with a periodically etched stripe pattern. We fabricated the plate through a standard lithographic formulation process by using a pyrex substrate glass with SU-8 resist coating on its one of the surfaces. The maximum insertion loss of the implemented filter was less than 2 dB over 1000 nm to 1600 nm and the extinction ratio was larger than 33 dB. The measured PDL within the 3-dB pass band of the filter was less than 0.15dB and the maximum extinction ratio variation was less than 2 dB even when the worst alignment error occured.

• Korean Journal of Materials Research
• /
• v.19 no.12
• /
• pp.657-660
• /
• 2009

Optical characteristics and structural changes depending on CuO content in phosphate glasses that are used in near-infrared (near-IR) filters were investigated. With phosphate glasses that contain 1-9 mol% CuO, changes in optical transmittance, optical absorption, and color coordinate were measured with a UV-VIS spectrophotometer. An XPS (X-ray photoelectron spectroscopy) analysis was performed to determine valence of copper ion that influences optical characteristics in near-IR filter glasses. Structural changes in glasses depending on CuO content were also analyzed by FT-IR (Fourier transform infrared) and Raman spectrophotometers. From the UV-VIS spectrophotometer results, strong absorption peaks at 220 & 900 nm were found and transmittance was decreased. The color coordinates of the glasses were shifted to the green color direction with CuO addition for increasing absorption of long wavelength range spectra, in spite of the amount of $Cu^{2+}$, which gives a blue color to glasses, and which was increased in XPS results. Also, structural de-polymerization of glasses with CuO addition were found by FT-IR and Raman results.

• Journal of Biosystems Engineering
• /
• v.32 no.4
• /
• pp.263-268
• /
• 2007

An auto sampling and filtering unit was developed for monitoring automation of a fermentation process and its performance was evaluated. The automatic sampling and filtering unit was constructed with a glass filter, a diaphragm suction pump, and a flow direction change valve. To evaluate operating stability, delivery volumes of the suction pump were measured according to the experimental conditions of cellulose powder, pore size of the glass filter and suction head of the pump. The developed unit could deliver the sample solution under any experimental conditions except the filter pore size of $16{\mu}m$ and the suction head of 20cm. In case of the suction head of 30cm, the pump could not deliver the sample solution at all. Concentrations of the sample solutions were converged on those of the standard glucose solution after 8 minutes from the initial sampling time. The relative error of concentration between the sample and the standard solution showed 3.8, 4.8, 7.0% for the 1, 3, 5% contents of cellulose powder, respectively.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.9
• /
• pp.1429-1434
• /
• 2004

Immunoassay is one of the important analytical methods for clinical diagnoses and biochemical studies, but needs a long time, troublesome procedures and expensive reagents. In this study, therefore, we propose the micro filter chip with microbeads for immunoassay, which has pillar structures. The advantage of the proposed micro filter chip is to use simple fabrication process and cheap materials. The mold was made by the photolithography technique with Si wafer and negative photoresist SU-8. The replica was made of PDMS, bonded on the pyrex glass. The micro filter chip consists of inlet channel, filter chamber and outlet channel. HBV (Hepatitius B virus) monoclonal antibody (Ag1) labeled with biotin were immobilized onto streptavidin coated beads of 30∼50 $\mu$m size. Fluorescein isothiocyanate (FITC)-labeled HBV monoclonal antibody (Ag8) was used to detect HBsAg (Hebatitis B virus surface Antigen), and fluorescence intensity was monitored by epi-fluorescence microscope. In this study, the immune response of less than 30 min was obtained with with the use of 100 $m\ell$ of sample.