• ETRI Journal
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• v.39 no.2
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• pp.264-274
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• 2017

Recently, mobile positioning enhancement has attracted much attention in the 3rd generation partnership project long-term evolution system. In particular, for urban canyon environments, the need for three-dimensional (3D) positioning has increased to enable the altitude of users to be measured. For several decades, several time difference of arrival (TDOA-) based 3D positioning methods have been studied; however, they are only available when at least four evolved Node Bs (eNBs) exist nearby or when all eNBs have the same height. Therefore, in this paper, we propose a new 3D positioning method that estimates the 3D coordinates of a user using three types of two-dimensional (2D) TDOAs. However, the give inaccurate results owing to the undefined axis of the 2D coordinate plane. Therefore, we propose a novel derivation of the hyperbola equation, which includes the undefined axis coordinate in the 2D hyperbola equation. Then, we propose an interaction algorithm that mutually supplies the undefined axis coordinate of users among 2D TDOAs. By performing extensive simulations, we verify that the proposed method is the only solution applicable by using three eNBs with different heights.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2613-2616
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• 2009

FeOOH/$TiO_2$, a heterojunction structure between FeOOH and $TiO_2$, was prepared by covering the surface of the $\sim$100-nm-sized FeOOH particles with Degussa P25 by applying maleic acid as an organic linker. Under visible light irradiation (${\lambda}{\geq}$ 420 nm), FeOOH/$TiO_2$ showed a notable photocatalytic activity in removal of gaseous 2-propanol and evolution of $CO_2$. It was found that FeOOH reveals a profound absorption in the spectral range of 400 - 550 nm, and its valence band (VB) level is located relatively lower than that of $TiO_2$. The considerable photocatalytic efficiency of the FeOOH/$TiO_2$ under visible light irradiation was therefore deduced to be caused by the hole transfer between the VB of FeOOH and $TiO_2$.

• Korean Journal of Materials Research
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• v.11 no.12
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• pp.1042-1046
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• 2001

Co-22%Cr alloy films are promising for high-density perpendicular magnetic recording media with their perpendicular anisotropy and large coercivity of 3000 Oe. We observed that a self organized nano structure(SONS) of fine ferromagnetic Co-enriched phase and paramagnetic Cr-enriched phase appears inside the grain of Co-Cr magnetic alloy thin films at the elevated substrate temperature after do-sputtering. We prepared 1000 $\AA$-thick Co-22%Cr films on 2000 $\AA$- SiO$_2$/Si(100) substrates at the deposition rate of 100 $\AA$/min with substrate temperatures of 3$0^{\circ}C$, 10$0^{\circ}C$, 15$0^{\circ}C$, 20$0^{\circ}C$, 30$0^{\circ}C$, and 40$0^{\circ}C$, respectively. We employed a vibrating sample magnetometer(VSM) to measure the B-H loops showing the saturation magnetifation, coercivity, remanence in in- plane and out- of- plane modes. In- plane coercivity, perpendicular coercivity, and perpendicular remanence increased as substrate temperature increased, how-ever they decreased after 30$0^{\circ}C$ slowly. Transmission electron microscope (TEM) characterization revealed that the self organized nano structure (SONS) appears at the elevated substrate temperature, which forms fine Co-enriched phases inside a grain, then it eventually affect the perpendicular magnetic property. Our results imply that we may tune the perpendicular magnetic properties with SONS obtained at appropriate substrate temperature.

• Journal of Microbiology and Biotechnology
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• v.33 no.12
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• pp.1587-1594
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• 2023

Since its first report in 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has posed a grave threat to public health. Virus-specific countermeasures, such as vaccines and therapeutics, have been developed and have contributed to the control of the viral pandemic, which has become endemic. Nonetheless, new variants continue to emerge and could cause a new pandemic. Consequently, it is important to comprehensively understand viral evolution and the roles of mutations in viral infectivity and transmission. SARS-CoV-2 beta variant encode mutations (D614G, N501Y, E484K, and K417N) in the spike which are frequently found in other variants as well. While their individual role in viral infectivity has been elucidated against various therapeutic antibodies, it still remains unclear whether those mutations may act additively or synergistically when combined. Here, we report that N501Y mutation shows differential effect on two therapeutic antibodies tested. Interestingly, the relative importance of E484K and K417N mutations in antibody evasion varies depending on the antibody type. Collectively, these findings suggest that continuous efforts to develop effective antibody therapeutics and combinatorial treatment with multiple antibodies are more rational and effective forms of treatment.

• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2348-2352
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• 2017

The electrical contact characteristics including temperature rise, contact resistance and arc erosion rate of the $Ag-SnO_2$ materials with increased $SnO_2$ content were investigated during the repeated make-and-break operations. The thickness of arcing melting layer reduces by half and the arc erosion rate decreases more than 70% under 10000 times operations at AC 10 A with the $SnO_2$ content increasing from 15 wt.% to 45 wt.%, on one hand, temperature rise and contact resistance increase obviously but could be reduced to the same order of conventional $Ag-SnO_2$ materials by increasing the contact force. The microstructure evolution and the effect of $SnO_2$ on the arc erosion, contact resistance were analyzed.

• Journal of Life Science
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• v.20 no.9
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• pp.1353-1357
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• 2010

Quantification of the ecosystem respiration is essential in understanding the carbon cycling of natural and disturbed landscapes. Soil respiration and some environmental factors which affect soil respiration were investigated in a Larix leptolepis plantation inKongju, Korea. Soil respiration was measured at midday of the $15^{th}$ and $30^{th}$ day of every month from May to December in a non-cutting area (Control) and a cutting area (Treatment) with IRGA Soil Respiration Analyzer. Throughout the study period, average soil temperature and water content were $23.3{\pm}0.5^{\circ}C$ and $27.76{\pm}7.12%$ for control, and $25.9{\pm}3.1^{\circ}C$ and $24.55{\pm}5.12%$ for treatment, respectively. There was a positive correlation ($R^2$=0.8905) between soil respiration and soil temperature in the study area. However, there was no significant correlation between soil respiration and soil moisture ($R^2$=0.4437). The seasonal soil respiration increased in the summer and decreased in the winter. In August, maximum soil respirations in the control and treatment areas were $0.82{\pm}0.13$ and $1.32{\pm}0.10$ $gCO_2{\cdot}^{-2}{\cdot}r^{-1}$, respectively. Total amounts of $CO_2$ evolution in the control and treatment areas from May to December in 2008 were 2,419.2 and 3,610.8 $CO_2g{\cdot}m^{-2}$, respectively. The amount of soil respiration in the treatment area was 49.3% greater than in the control. Increased soil respiration in the treatment area may be due to increased soil temperature, which drives increased microbial decomposition. According to our present investigation, forest cutting will increase the atmospheric $CO_2$ by increasing soil respiration.

• Analytical Science and Technology
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• v.8 no.4
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• pp.583-590
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• 1995

Pitch-based mesophase carbon fibers prepared at different temperatures were heat-treated at temperatures lower than those of the preparation and the electrochemical Li doping/undoping characteristics were evaluated in relation to the data of IR, mass, etc. Presence of surface hydroxyls were confirmed by FTIR for lower temperature sample which showed poor anode characteristics. Upon oxidative heating, removal of surface hydroxyls took place, resulting in a remarkable improvement of the electrode characteristics. At the same time, surface roughening took place, which was confirmed by SEM and double layer capacity measurements. In situ mass spectra obesrved during the heat-treatments showed gas evolution of $H_2O$, CO, $CO_2$, $C_2H_4$, and/or $H_2$ depending on the conditions. These data together with those of weight loss and conductivity provided us a valuable information in regard to the evaluation of the electrochemical characteristics.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.85.2-85.2
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• 2012

The interstellar medium (ISM) of galaxies in the galaxy cluster can well be affected by the intracluster medium (ICM). Among many suggested environmental processes, ram pressure stripping can effectively remove gas through the interaction with the ICM. In fact, Cluster galaxies are lower in HI gas mass compared to their field counterparts, and in recent high resolution HI imaging studies, many galaxies in dense environments have been found to be ram pressure stripped in HI. However, it is still under debate whether the ICM pressure can also remove dense molecular gas from the galactic disk, which plays more important role in star formation and hence galaxy evolution. To answer this question, we have obtained high resolution 12/13 CO (2-1) data from the Sub Millimeter Array (SMA) of four galaxies at various HI stripping stages to study how the molecular gas properties change as the galaxy experiences the ICM pressure. We investigate the physical properties of molecular gas with 12/13 CO images. By comparing with other wavelength data, i.e. data(optical, HI, $H{\alpha}$, etc), we discuss how and in which timescale galaxies can migrate from the blue cloud to the red sequence due to ram pressure stripping.

• Korean Journal of Agricultural Science
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• v.22 no.1
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• pp.54-61
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• 1995

In order to investigate the effects of Ganoderma lucidum on the fermentation of media by Kluyveromyces fragilis KCCM 35458, with 0%, 0.1%, 0.5%, and 1.0% (w/v) of Ganoderma lucidum extract were added to skin milk and fermented in the suspension culture at $30^{\circ}C$ for 72 hours. The pH, acidity, $CO_2$ evolution, alcohol production, number of yeast cells and lactose content were investigated. The results are summarized as follows; 1. As fermentation time advanced by the pH was decreased and the acidity was increased in the media of 1.0% Gnaoderma lucidum extract as fermentation time advanced. 2. $CO_2$ evolution was increased in the all of Genoderma lucidum extract and significantly effect showed in 1.0% extract medium. 3. During 72 hours culturing, alcohol was detected in all Gandoderma lucidum extract media, 1.0% Ganoderma lucidum extract medium showed extremly high in alcohol and shortened fermentation time. 4. The number of yeast was increased more at logarithmic phase and the growth of yeast was more rapid in all Ganoderma lucidum extract especially 0.5%, 1.0% media samples than control. 5. As fermentation time goes by, the lactose content of media were decreased more rapidly in 1.0% Ganoderma lucidum extract medium than control.

• Microbiology and Biotechnology Letters
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• v.47 no.4
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• pp.565-573
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• 2019

Production of biofuels and value-added materials from cellulosic biomass requires the development of a microbial strain capable of efficiently fermenting mixed sugars. In this study, the natural xylose fermenting yeast, Pichia stipitis, was evolved to simultaneously ferment cellobiose and xylose. Serial subcultures of wild-type P. stipitis in 20 g/l cellobiose were performed to increase the rate of cellobiose consumption. A total of ten rounds of the serial subculture led to the isolation of an evolved strain fermenting cellobiose significantly faster than the parental strain. The evolved strain displayed enhanced ethanol yield from 0 to 0.4 g ethanol/g cellobiose. The evolved P. stipitis simultaneously fermented cellobiose and xylose in batch fermentation. The genetic information of our evolved P. stipitis would be valuable in the development of a microbial host for the production of biofuels and biomaterials from cellulosic biomass.