• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.36.1-36.1
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• 2020

The progenitor of Type Ia supernovae (SNe Ia) is mainly believed to be a carbon/oxygen white dwarf (WD) with non-degenerate (single degenerate) or another WD companion (double degenerate). However, there is little observational evidence of their progenitor system. Recent studies suggest that shock-breakout cooling emission after the explosion can constrain the size of the progenitor system. To do so, we obtained a optical/Near-IR light curve of SN 2019ein, a normal but slightly sub-luminous type Ia supernova, from the very early phase using our high-cadence observation of Intensive Monitoring Survey of Nearby Galaxies (IMSNG). Assuming the expanding fireball model, the simple power-law fitting of the early part of the light curve gives power indices of 1.91 (B) and 2.09 (R) implying radioactive decay of 56Ni is the dominant energy source. By comparison with the expected light curve of the cooling emission, the early observation provides us an upper limit of the companion size of R∗≤1R⊙. This result suggests that we can exclude a large companion such as red giants, which is consistent with the previous study.

• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.5
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• pp.25-35
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• 2023

The estuary reservoir is a major source of agricultural water in Korea; for effective and sustainable water resource management of the estuary reservoir, it is crucial to comprehensively consider various water resource factors, including water supply, flood, and pollutant management, and analyze future runoff changes in consideration of environmental changes such as climate change. The objective of this study is to estimate the impact of future climate change on the runoff characteristics of an estuary reservoir watershed. Climate data on future Shared Socioeconomic Pathway (SSP) scenarios were derived from two Global Climate Models (GCMs) of the Coupled Model Intercomparison Project phase 6 (CMIP6). The Hydrological Simulation Program-Fortran (HSPF) was used to simulate past and future long-term runoff of the Ganwol estuary reservoir watershed. The findings showed that as the impact of climate change intensified, the average annual runoff in the future period was higher in the order of SSP5, SSP3, SSP1, and SSP2, and the ratio of runoff in July decreased while the ratio of runoff in October increased. Moreover, in terms of river flow regime, the SSP2 scenario was found to be the most advantageous and the SSP3 scenario was the most disadvantageous. The findings of this study can be used as basic data for developing sustainable water resource management plans and can be applied to estuary reservoir models to predict future environmental changes in estuary reservoirs.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.6
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• pp.878-888
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• 2023

Growth responses of Chlorella vulgaris exposed to different light intensities and wavelengths of light-emitting diodes (LEDs) were investigated. C. vulgaris was cultured under red LED (650 nm), blue LED (450 nm), green LED (520 nm), and fluorescent lamps (three wavelengths, control). The maximum growth rates (µ_max) of C. vulgaris were highest under the blue LED, followed by the red LED, green LED, and fluorescent lamps. The low compensation photon flux density (I₀) and low half-saturation constants (K_s) were observed in C. vulgaris cultured under the red LED, indicating that high C. vulgaris growth is closely related to the low light intensity of the red LED suggesting that the red LED can be useful for the biomass production of C. vulgaris. Furthermore, it was observed that under the blue LED during the stationary phase, there was an increase in useful bioactive substances, such as proteins and lipids, which are beneficial for biomass production. In conclusion, the red LED is an economical light source that can enhance cell density, and the blue LED is effective in promoting valuable intracellular substances.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.2
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• pp.48-54
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• 2024

During the Hg₂Br₂ physical vapor transport process with self-diffusion, it is concluded that for 10^-3g₀≤ g ≤ 1g₀ the thermal buoyancy driven convection is dominant in the vapor phase; at the gravitational level of g = 10^-4g₀, the transition region from the convection to diffusion occurs; for 10^-6g₀ ≤ g ≤ 10^-5g₀, the diffusion mode is predominant. The total molar flux of Hg₂Br₂ decays exponentially with the decreasing of one tenth of gravitational magnitude. For 10℃ ≤ ΔT ≤ 50℃, the total molar flux increases linearly and directly with the temperature difference between the source and crystal regions.

• The Journal of the Acoustical Society of Korea
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• v.28 no.5
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• pp.461-470
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• 2009

We investigate and analyze the problems encountered in frame-based estimation of TDOA (Time Difference of Arrival) using CPSP function. Spectral leakage occurring in framing of a speech signal by a rectangular window could make estimation of CPSP spectrum inaccurate. Framing with other windows to reduce the spectral leakage distorts the signal due to the asynchronous weighting around the frame specifically both ends of the frame. These problems degrade the performance of the CPSP-based TDOA estimation. In this paper, we propose a method to alleviate those problems by pre-emphasis of the speech signal. It reduces the influence of the spectral leakage by reducing dynamic range of the spectrum of a speech signal with pre-emphasis. To validate the proposed method of pre-emphasis, we carry out TDOA estimation experiments in various noise and reverberation conditions, Experimental results have shown that the framing of pre-emphasized microphone output by a rectangular window achieves higher success rate of TDOA estimation than any other framing methods.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.57 no.3
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• pp.216-226
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• 2024

This study screened the antimicrobial and anti-inflammatory activities of three extracts [1% acetic acid (HAc), distilled water (D.W.), and ethanol] from the common stalked barnacle Pollicipes mitella. Among the extracts, the 1% HAc extract showed the strongest antibacterial activity against several bacteria, but exhibited no activity against Candida albicans. To improve the degree of separation of the 1% HAc extract, solid-phase extraction was performed using a C18 cartridge with three solvents (D.W., 60A, and 100A). The 1% HAc 60A eluate showed the strongest antibacterial activity and enzyme, salt, and temperature stability, with no hemolytic activity. In addition, strong DNA-binding ability but no bacterial membrane permeability was observed. These results indicate that the P. mitella 1% HAc 60A eluate may contain antibacterial organic compounds that target intracellular components but not bacterial membranes. In addition, the 1% HAc 60A eluate exhibited potent inhibitory activity to reduce the production of inflammatory mediators (nitric oxide and prostaglandin E₂) and pro-inflammatory cytokines (tumor necrosis factor-α, interleukin (IL)-6, and IL-1β) with no cytotoxicity. Therefore, the P. mitella 1% HAc 60A eluate has anti-inflammatory activity. Collectively, our results suggest that the P. mitella 1% HAc 60A eluate can be used as a bioactive source with antibacterial and anti-inflammatory activities.

• Korean Journal of Materials Research
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• v.34 no.8
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• pp.377-386
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• 2024

The surface of titanium (Ti) dental implants was modified by applying a zinc (Zn)-doped titanium dioxide (TiO₂) coating. Initially, the Ti surfaces were etched with NaOH, followed by a hydrolysis co-condensation using tetrabutyl titanate (TBT, Ti(OC₄H₉)₄) and zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O), with ammonia water (NH₃·H₂O) acting as a hydroxide anion source. The morphology and chemical composition of the Zn-doped TiO₂-coated Ti plates were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and scanning electron microscopy (SEM). Synthesis temperatures were carefully adjusted to produce anatase Zn-doped TiO₂ nanoparticles with a bipyramidal structure and approximate sizes of 100 nm. Wettability tests and cell viability assays demonstrated the biomedical potential of these modified surfaces, which showed high biocompatibility with a survival rate of over 95 % (p < 0.05) and improved wettability. Corrosion resistance tests using potentiodynamic polarization reveal that Zn-TiO₂-treated samples with an anatase crystal structure exhibited a lower corrosion current density and more noble corrosion potential compared to samples coated with a rutile structure. This method offers a scalable approach that could be adapted by the biomaterial industry to improve the functionality and longevity of various biomedical implants.

• Herbal Formula Science
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• v.32 no.3
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• pp.223-233
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• 2024

Objectives : Natural products containing bioactive compounds with high antioxidant activity are potentially important sources that can contribute to the improvement of various diseases. Therefore, the aim of this study was to investigate phenolic compounds of Cinnamomum cassia (C. cassia) ethanolic extract (CCEE). And then we evaluated the antioxidant effect. Methods : We used liquid chromatography with tandem mass spectrometry (LC-MS/MS) to identify the compounds in CCEE. LC-MS/MS was performed in positive ion mode using Shimadzu, Nexera HPLC system and IDA TOF mass system. Solvent A was distilled water and solvent B was acetonitrile as mobile phase. The analysis was performed at a flow rate of 0.5 ml/min, column temperature of 35 ℃ and wavelength of 284 nm. The antioxidant effect of CCEE was analyzed using DPPH (2,2-diphenyl-2-picrylhydrazyl free radical) and ABTS (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)). In addition, total phenolics and total flavonoids contents were measured to determine antioxidant effects. Results : Analysis using LC-MS/MS identified four compounds: Coumarin, Trans-cinnamaldehyde, Trans-cinnamic acid, and 2-Methoxycinnamaldehyde. Free radicals decreased in a concentration-dependent manner starting from 10 ㎍/ml of CCEE, and decreased to a level similar to Ascorbic acid (AA) from a concentration of 60 ㎍/ml onwards. Conclusions : Based on the findings, CCEE exhibits strong antioxidant activity as evidenced by the presence of Coumarin, Trans-cinnamaldehyde, Trans-cinnamic acid, and 2-Methoxycinnamaldehyde. Consequently, this study suggests that CCEE can serve as an important source of natural antioxidants and can be efficiently used in the management of oxidative stress diseases.

• Clinical and Experimental Vaccine Research
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• v.11 no.1
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• pp.43-52
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• 2022

Purpose: Indonesia, a high populous and the second-highest country in epidemicity of hepatitis B in South-East Asia require maintaining its capacity of monovalent hepatitis B production to keep up with both the national immunization program and global needs. To keep the sustainability of the vaccine, a new bulk is needed to be made available. This study aims to evaluate the immunogenicity and safety of Bio Farma newly formulated recombinant hepatitis B vaccines, which came from different sources of bulk, compared to the already registered hepatitis B vaccine. Materials and Methods: An experimental, randomized, double-blind, cohort intervention phase II clinical trial was conducted on three recombinant hepatitis B vaccines from different bulk sources, with Bio Farma registered hepatitis B vaccine as the control group. A total of 536 participants around age 10 to 40 years old were thricely vaccinated with twice serological assessments. The subject's safety was monitored for 28 days after each vaccination. Results: Of 536 enrolled participants, 521 finished the vaccination and serology assessments. The investigational products were proven not to be inferior to the control. All vaccines were well tolerated. No differences in rates of local and systemic reactions were seen between the investigational products and control. No serious adverse event was found to be related to the investigational vaccines. Conclusion: Investigational vaccines are shown to be equally immunogenic and safe as the control vaccine.

• Korean Journal of Agricultural Science
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• v.8 no.2
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• pp.238-243
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• 1981

This experiment was carried out to study the availability of Korean peat as a main carrier material of rhizobial inoculant, using the alfalfa strain Rhizobium meliloti M 14 which was isolated in the previous report. Modification of powdered peat with calcium carbonate and other materials was studied; inoculation of the peat with culture broth, maturation of the mixture under different conditions, and survival of the strain in the peat culture was examined. The results obtained were as follows. 1. Peat produced in Pyongtak was highly acidic, pH 3.8, and addition of calcium carbonate by 14% was required for pH adjustment to 6.4. However the amount of calcium carbonate could be reduced by 4 to 8% when carbon or charcoal was mixed with the peat. 2. Viable number of the strain reached to $7-9{\times}10^9cells/g$ after 3 days, when inoculated with the culture broth of early stationary growth phase and matured in unsteriled peat of open trays; and the number in steriled peat was $1.1-6.2{\times}10^{10}cells/g$ after 5 days, when matured in closed bottles. 3. Survival of the strain was affected markedly by storage temperature, and positive effect of D-sorbitol on the viability was recognized at elevated temperatures, when added as an additional carbon source and moistening agent. Glycerol, sorbitol, or sodium lactate was utilized by the strain as a sole source of carbon, and the decimal reduction time of viable number in the peat culture was was found to be 8 to 9 weeks at $25^{\circ}C$ when these agents were added by 0.5%.