• Journal of Korean Society on Water Environment
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• v.34 no.6
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• pp.579-590
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• 2018

The lakes' metabolism bears important information for the assessment of the carbon budget due to the accumulation or loss of carbon in the lake as well as the dynamics of the food webs through primary production. A lake-scale metabolism is evaluated by Gross Primary Production (GPP), Ecosystem Respiration (R), and Net Ecosystem Production (NEP), which is the difference between the first two values. Methods for estimating GPP and R are based on the levels carbon and oxygen. Estimation of carbon is expensive because of the use of radioactive materials which requires a high degree of proficiency. The purpose of this study was to estimate Lake Daecheong ecosystem metabolism using high frequency water temperature data and DO measurement sensor, widely utilized in the field of water quality monitoring, and to evaluate the possibility of using the application method. High frequency data was collected at intervals of 10 minutes from September to December 2017 by installing a thermistor chain and a DO sensor in downstream of Daechung Dam. The data was then used to estimate GPP, R and NEP using the R public program LakeMetabolizer, and other metabolism models (mle, ols, kalman, bookkeep). Calculations of gas exchange coefficient methods (cole, crusius, heiskanen, macIntyre, read, soloviev, vachon) were compared. According to the result, Lake Daecheong has some deviation based on the application method, but it was generally estimated that the NEP value is negative and acts as a source of atmospheric carbon in a heterotrophic system. Although the high frequency sensor data used in this study had negative and positive GPP and R values during the physical mixing process, they can be used to monitor real-time metabolic changes in the ecosystem if these problems are solved.

• Pediatric Infection and Vaccine
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• v.30 no.2
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• pp.73-83
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• 2023

Purpose: This study aimed to investigate the viral load dynamics in children with underlying malignancies diagnosed with symptomatic coronavirus disease 2019 (COVID-19). Methods: This was a retrospective longitudinal cohort study of patients <19 years old with underlying hemato-oncologic malignancies that were diagnosed with their first symptomatic severe acute respiratory syndrome coronavirus 2 polymerase chain reaction (PCR)-confirmed COVID-19 infection during March 1 to August 30, 2022. Review of electronic medical records and telephone surveys were undertaken to assess the clinical presentations and transmission route of the patients. Thresholds of negligible likelihood of infectious virus was defined as E gene reverse transcription (RT)-PCR cycle threshold (Ct) value ≥25. Results: During the 6-month study period, a total of 43 children with 44 episodes of COVID-19 were included. Of the 44 episodes, the median age of the patients included was 8 years old (interquartile range [IQR], 4.9-10.5), and the most common underlying disease was acute lymphoid leukemia (n=30, 68.2%), followed by patients post-hematopoietic stem cell transplantation (n=8, 18.2%). Majority of the patients had mild COVID-19 (n=32, 72.7%), and three patients (7.0%) had severe/critical COVID-19. Furthermore, 2.3% (n=1) died of COVID-19 associated acute respiratory distress syndrome. The largest percentage of the patients showed E gene RT-PCR Ct value ≥25 between 15-21 days (n=13, 39.4%), followed by 22-28 days (n=10, 30.3%). In 15.2% (n=5), E gene RT-PCR Ct value remained <25 beyond 28 days after initial positive PCR. Refractory malignancy status (β, 67.0; 95% confidence interval, 7.0-17.0; P=0.030) was significantly associated with prolonged duration of E gene RT-PCR <25. A patient with prolonged duration of E gene RT-PCR Ct value <25 was suspected to have infectivity shown by the transmission of the virus to his mother at day 86 after his initial positive test. Conclusions: Children that acquire symptomatic COVID-19 during refractory malignancy state are at a high risk for prolonged shedding warranting PCR-based transmission precautions in this cohort of patients.

• Korean Journal of Animal Reproduction
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• v.25 no.4
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• pp.359-369
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• 2001

Polymerase chain reaction (PCR) amplification of DNA as 30 different arbitrary primers and random amplified polymorphic DNAs (RAPD) analysis were performed on genomic DNA extracted from the blood of the marine rockfish (Sebastes schlegeli) from the Yellow Sea and the Southern Sea. The unique properties of the genomic DNA were used to investigate the features of the population dynamics and origins of the species. Out of 30 primers, seven generated 207 highly reproducible RAPD polymorphic products, producing approximately 2.7 polymorphic bands per primer. About 67.4% of total amplified products (307) were either polymorphic (207) to rockfish. The degree of similarity varied from 0.22 to 0.63 as calculated by bandsharing analysis. Also, the average level of bandsharing was 0.39$\pm$0.02 within the rockfish strains. The electrophoretic analysis of RAPD-PCR products showed the relatively high levels if variation between different individuals in rockfish from the Yellow Sea. However, the RAPD outlines obtained with DNA of different rockfish strains from the Yellow Sea and the Southern Sea in Korea were very similar. Also, a small number of polymorphic bands were identified. Even if further analyses or more rockfish populations are required, this result implies RAPD analysis reflects genetic differences between the geographical strains of the rockfish.

• Polymer(Korea)
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• v.30 no.3
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• pp.271-278
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• 2006

In order to investigate the structure and dynamics of atatic poly (vinyl alcohol) (PVA)/water system, laser light scattering experiment has been done in the semi-dilute concentration regime at $25^{\circ}C$. The scattering intensity I(q) can be analyzed with the fractal equation of $I(q){\sim}q^{-m}$ instead of Onstein-Zernike type equation. The fractal dimensionality m was found to be constant after reaching the plateau value of $m=2.6{\pm}0.3$ above C=3wt%. The time correlation function of dynamic light scattering has always two different modes such as fast mode and slow one. The cooperative diffusion of fast mode showed concentration independence contrary 4o the reptation theory's concentration dependent exponent of 3/4. The slow mode can be interpreted as the motion of large scale heterogeneities and its strong concentration dependence is apparent with a large negative exponent of -3.0. It is considered that the stereo-regular arrangement with four successive meso units of -OH plays as a key role in forming such heterogeneity.