• ALGAE
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• v.37 no.4
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• pp.281-291
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• 2022

Quantifying the abundance of Chattonella species is necessary to effectively manage the threats from ichthyotoxic raphidophytes, which can cause large-scale mortality of aquacultured fish in temperate waters. The identification and cell counting of Chattonella species have been conducted primarily on living cells without fixation by light microscopy because routine fixatives do not retain their morphological features. Species belonging to the Chattonella marina complex, including C. marina and C. marina var. ovata, had high genetic similarities and the lack of clear morphological delimitations between the species. To estimate the abundance of C. marina complex in marine plankton samples, we developed a protocol based on the droplet digital polymerase chain reaction (ddPCR) assay, with C. marina complex-specific primers targeting the internal transcribed spacer (ITS) region of the rDNA. Cell abundance of the C. marina complex can be determined using the ITS copy number per cell, ranging from 25 ± 1 for C. marina to 112 ± 7 for C. marina var. ovata. There were no significant differences in ITS copies estimated by the ddPCR assay between environmental DNA samples from various localities spiked with the same number of cells of culture strains. This approach can be employed to improve the monitoring efficiency of various marine protists and to support the implementation of management for harmful algal blooms, which are difficult to analyze using microscopy alone.

• Genomics & Informatics
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• v.15 no.1
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• pp.2-10
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• 2017

Early detection and proper management of kidney rejection are crucial for the long-term health of a transplant recipient. Recipients are normally monitored by serum creatinine measurement and sometimes with graft biopsies. Donor-derived cell-free deoxyribonucleic acid (cfDNA) in the recipient's plasma and/or urine may be a better indicator of acute rejection. We evaluated digital PCR (dPCR) as a system for monitoring graft status using single nucleotide polymorphism (SNP)-based detection of donor DNA in plasma or urine. We compared the detection abilities of the QX200, RainDrop, and QuantStudio 3D dPCR systems. The QX200 was the most accurate and sensitive. Plasma and/or urine samples were isolated from 34 kidney recipients at multiple time points after transplantation, and analyzed by dPCR using the QX200. We found that donor DNA was almost undetectable in plasma DNA samples, whereas a high percentage of donor DNA was measured in urine DNA samples, indicating that urine is a good source of cfDNA for patient monitoring. We found that at least 24% of the highly polymorphic SNPs used to identify individuals could also identify donor cfDNA in transplant patient samples. Our results further showed that autosomal, sex-specific, and mitochondrial SNPs were suitable markers for identifying donor cfDNA. Finally, we found that donor-derived cfDNA measurement by dPCR was not sufficient to predict a patient's clinical condition. Our results indicate that donor-derived cfDNA is not an accurate predictor of kidney status in kidney transplant patients.

• Journal of dental hygiene science
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• v.12 no.6
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• pp.660-665
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• 2012

The purpose of this study was to use basic data of dental hygiene curriculum by comparing the rolling method and modified stillman method. Plaque measurement method, Q-ray examination of the clinical utilization value shall review. True experimental design is randomized controlled trial to the intervention group and the control group. Measurements are plaque control record (PCR; O'Leary index) measurements and Quantitative Light induced fluorescnece Digital (QLFD) shooting as a pre-test was conducted. Intervention group is modified stillman method, control group is rolling method. Intervention after 5 weeks, PCR measurement and QLFD shooting was carried out as a post-test. Rolling method and modified stillman method plaque reduction did not differ. Intervention before and after the results of the comparison showed reduced plaque score after brushing law education. Also, Plaque reduction differences were more pronounced modified stillman method than rolling method. PCR and QLFD values of the correlation was not confirmed but SPS Score and the lower value of the ${\Delta}R$ value of the correlation. Plaque of maturity tooth that are not observed visually.

• Journal of the Institute of Convergence Signal Processing
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• v.6 no.2
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• pp.95-99
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• 2005

This paper presents an accurate recovery method of the reference clock which is needed for network synchronization in two-way satellite multimedia systems compliant with DVB-RCS specification and which use closed loop method for burst synchronization. In these systems, the remote station transmits TDMA burst via return link. For burst synchronization, it obtains reference clock from program clock reference (PCR) defined by MPEG-2 system specification. The PCR is generated periodically at the hub system by sampling system clock which runs at 27MHz $\pm$ 30ppm. Since the reference clock is recovered by means of digital PLL(DPLL) using imprecise PCR values due to variable random jitter, the recovered clock frequency of remote station doesn't exactly match reference clock of hub station. We propose a robust recovery method of reference clock against random delay jitter The simulation results show that the recovery error is remarkably decreased from 5 clocks to 1 clock of 27MHz relative to the general DPLL recovery method.

• Journal of Dairy Science and Biotechnology
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• v.31 no.2
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• pp.171-177
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• 2013

The dairy industry has consistently grown via the expansion of dairy-based food categories. Dairy product consumption is stable since the nutrient composition in dairy products is ideal for human health. However, dairy products are highly susceptible to food-borne pathogens. Controlling the safety of dairy products is thus important when considering the nutrient-rich matrix of this food category. Currently, immunoassays or molecular biology techniques have been used to evaluate the safety of dairy products in Korea. These methods are based on the detection of proteins and thus have low reproducibility and sensitivity. Recent techniques to detect food-borne pathogens have focused on genetic analyses. Rapid detection methods for food-borne pathogens in milk and dairy products using polymerase chain reaction (PCR) techniques, such as conventional PCR, real-time PCR, repetitive sequence-based (rep)-PCR, PCR-denaturing gradient gel electrophoresis (DGGE), and digital PCR, are reviewed in this article. The aim of this review was to contribute knowledge of the relationship between microflora and the quality of dairy products. This study will also assist in the immediate monitoring of food-borne pathogens in milk and dairy products when an outbreak related to this food category occurs.

• Korean Journal of Ecology and Environment
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• v.52 no.4
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• pp.394-402
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• 2019

The Agrobacterium tumefaciens mediated gene transfer is widely used to generate genetic transformation of plants and transient assay of temporal exogenous gene expression. Syringe infiltration system into tobacco (Nicotiana benthamiana) leaves is a powerful tool for transient expression of target protein to study protein localization, protein-protein binding and protein production. However, the protocol and technical information of transient gene expression, especially double strand RNA (dsRNA), in tobacco using Agrobacterium is not well known. Recently, dsRNA is crucial for insecticidal effect on destructive agronomic pest such as Corn rootworm. In this study, we investigated the factor influencing the dsRNA expression efficiency of syringe agro-infiltration in tobacco. To search the best combination for dsRNA transient expression in tobacco, applied two Agrobacterium cell lines and three plant vector systems. The efficiency of dsRNA expression has estimated by real-time PCR and digital PCR. As a result, pHellsgate12 vector constructs showed the most effective accumulation of dsRNA in the cell. These results indicated that the efficiency of dsRNA expression was depending on the kind of vector rather than Agrobacterium cells. In summary, the optimized combination of transient dsRNA expression system in tobacco might be useful to in vivo dsRNA expression for functional study and risk assessment of dsRNA.

• Biomedical Science Letters
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• v.29 no.4
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• pp.363-370
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• 2023

Human respiratory viral infections such as COVID-19 are highly contagious, so continuous management of airborne viruses is essential. In particular, indoor air monitoring is necessary because the risk of infection increases in poorly ventilated indoors. However, the current method of detecting airborne viruses requires a lot of time from sample collection to confirmation of results. In this study, we proposed a system that can monitor airborne viruses in real time to solve the deficiency of the present method. Air samples were collected in liquid form through a bio sampler, in which case the virus is present in low concentrations. To detect viruses from low-concentration samples, viral RNA was concentrated and extracted using silica-magnetic beads. RNA binds to silica under certain conditions, and by repeating this binding reaction, bulk samples collected from the air can be concentrated. After concentration and extraction, viral RNA is specifically detected through real-time qPCR (quantitative polymerase chain reaction). In addition, based on liquid handling technology, we have developed an automatic machine that automatically performs the entire testing process and can be easily used even by non-experts. To evaluate the system, we performed air sample collection and automated testing using bacteriophage MS2 as a model virus. As a result, the air-collected samples concentrated by 45 times then initial volume, and the detection sensitivity of PCR also confirmed a corresponding improvement.

• Journal of Digital Convergence
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• v.18 no.12
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• pp.425-434
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• 2020

Background: Viral infection outbreaks are emerging public health concerns. They often exhibit seasonal patterns that could be predicted by the application of big data and bioinformatic analyses. Purpose: The purpose of this study was to identify trends in diarrhea-causing viruses such as rotavirus (Gr.A), norovirus G-I, and norovirus G-II in Cheonan, Korea. The identified related factors of diarrhea-causing viruses may be used to predict their trend and prevent their infections. Method: A retrospective analysis of 4,009 fecal samples from June 2010 to December 2019 was carried out at Dankook University Hospital in Cheonan. Reverse transcription-PCR (RT-PCR) was employed to identify virus strains. Information about seasonal patterns of infection was extracted and compared with local weather data. Results: Out of the 4,009 fecal samples tested using multiplex RT-PCR (mRT-PCR), 985 were positive for infection with Gr.A, G-I, and G-II. Out of these 985 cases, 95.3% (n = 939) were under 10 years of age. Gr.A, G-I, and G-II showed high infection rates in patients under 10 years of age. Student's t-test showed a significant correlation between the detection rate of Gr.A and the relative humidity. The detection rate of G-II significantly correlated with wind-chill temperature. Conclusion: Climate factors differentially modulate rotavirus and norovirus infection patterns. These observations provide novel insights into the seasonal impact on the pathogenesis of Gr.A, G-I, and G-II.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.1
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• pp.31-38
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• 1991

A direct digital control technique of a current source using the phase-controlled rectifier is presented. A digital firing technique without sensing the line voltage is proposed. This scheme generates firing pulses directly from error signal between command and output voltage. Thus the phase detection transformers filters and zero-crossing detector are unnecessary. The synchronism is modeled and analized. Also a software synchronization algorithm is presented without a look up table and controls the system in real time with fast dynamic characteristics. Using the single-chip microprocessor 8097BH, the direct digital control is implemented with minimal hardware structure. Using the time-weighted performance index, the optimal discrete IPM control technique is also proposed to control the current of the PCR.

• Journal of Digital Convergence
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• v.14 no.10
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• pp.349-354
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• 2016

The emergence and dissemination of extended-spectrum ${\beta}$-lactamse (ESBL) producing Klebsiella pneumoniae isolates make it more difficult to treatment of bacterial infections. In our study, we detected ESBL genes and investigated antimicrobial susceptibility of K. pneumoniae isolates in Chungcheong province. In addition, clonality among the isolates was analyzed by repetitive element sequence (REP)-PCR. Twenty-one of 102 K. pneumoniae isolates produced CTX-M-14 and/or CTX-M-15 and showed high level (over 70%) resistance to third cephalosporins. CTX-M type ESBL producing K. pneumoniae strains isolated in our study showed diverse clonality and some of the isolates have been disseminated in the community. Enhancing infection control will be needed to prevent dissemination of the K. pneumoniae isolates. In addition, for more effective control of resistant bacteria it is considered necessary to monitor the database constructed through convergence of biological investigation and statistical analysis of antimicrobial resistance genes.