• Journal of the Korean Institute of Landscape Architecture
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• v.32 no.5
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• pp.23-34
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• 2004

In this study, 1 dependent variable and 9 independent variables were established to examine suitable illuminance by spaces in urban parks in consideration of night users' psychological reactions and activity types. Such fixed variables were evaluated by a series of experiments of changing illuminance, and correlation among those variables was verified by correlation analysis and multiple regression analysis to suggest suitable illuminance by spaces. The results of this study are as follows: 1) The independent variables influencing suitable illuminance by spaces in urban parks were directly influenced rather by the psychological reaction of night users than the activity types by spatial functions. 2) Securing suitable illuminance by spaces commonly increased spatial availability, created certain atmosphere, and provided safety in the psychological reaction of night users. 3) Suitable illuminance by spaces in urban parks is: Central square is 31.88lx, resting space 6.30lx, exercising space 33.14lx, children's playground 14.19lx, pedestrian road 12.29lx, entry space 16.30lx, and green space 7.03lx. That is, when a place had more positive activities, spatial illuminance was increased. 4) Though comparison by spaces with the illuminance standard for urban parks as mentioned in KS A 3011-1993 can not be made, such illuminance was relatively compatible with the permissible range of illuminance in the author's opinion. It is expected that this study investigating suitable illuminance by spaces for night use in urban parks, will provide necessary knowledge for securing suitable illuminance by spaces in urban parks through classifyingin detail the illuminance standard of KS A 3011-1993. Besides, by helping make us aware of the importance of illuminance in urban parks as well as of external space in the night, this study will contribute to academic research and development in the field of landscape architecture and associated fields and be utilized in establishing legal and institutional standards.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.35.3-36
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• 2016

We explore the role of bars in AGN-galaxy co-evolution using a volume-limited face-on late-type galaxy sample with $M_r$ < -19.5 and 0.02 < z < 0.055 selected from SDSS DR7. In this study, we investigate how $SFR_{fib}$ as a proxy of gas contents at galactic center (over 1~1.5 kpc bulge scale) and central stellar velocity dispersion, ${\sigma}$, of host galaxies are connected to the bar presence and AGN activity. We find that galaxies are distributed in three distinct regions over the $SFR_{fib}-{\sigma}$ space and the behaviors of their bar fraction ($f_{Bar}$) are clearly different for each region. Galaxies at the AGN dominant region tend to be gas-deficient as $f_{Bar}$ increases and bars are more frequently found in fully-quenched late-type galaxies at the quiescent region, suggesting that bars speed up of the consumption of gas by SF and lead a sudden decline in the central gas. Overall, the bar effects on the AGN activity are positive over the same space except for quiescent galaxies with ${\sigma}$ > $170km\;s^{-1}$. Most significant bar effect on the AGN activity occurs in the less massive galaxies having sufficient gas, whereas the effect on galaxies at the AGN dominant region with higher the AGN fraction is relatively small. We suggest that the bar affect both central SF and AGN activities, but differently for central gas amount and BH (or bulge) mass of galaxies. We also investigate the AGN-bar connection with only pure AGNs and then confirm that they give marginally the same results.

• Korean Journal of Child Studies
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• v.12 no.2
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• pp.51-66
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• 1991

The purpose of study I was to investigate developmental processes and sex differences in the acquisition of topological seriation and Euclidean horizontal/vertical concepts. The purpose of Study II was to investigate the effects of basic geometric activity on the acquisition of space concepts. The subjects of Study I were 164 five- and six-year-old children. The children were grouped by age in 6 month units. The subjects of Study II were 45 children who showed immature space concepts. The data were analyzed by two-way ANOVA, $Scheff{\acute{e}}^{\prime}s$ posthoc test, and paired comparison t-test. On Study I, significant differences were found among the age groups in each of the dependent variables. Sex differences were found on all tasks except cued Euclidean tasks. In Study II, basic geometric activity of 3 weeks duration was found to be effective in the acquisition of the horizontal/vertical concepts in children whose space concept had been immature.

• Journal of Microbiology and Biotechnology
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• v.10 no.3
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• pp.333-337
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• 2000

An oil-degrading yeast, Yarrowia lipolytica 180, exhibits interesting cell surface characteristics under the growth on hydrocarbons. An electron microscopic study revealed that the cells grown on crude oil showed protrusions on the cell surface, and thicker periplasmic space and cell wall than the cell surface, and thicker periplasmic space and cell wall than the cells grown on glucose. Y. lipolytica cells lost its cell hydrophobicity after pronase(0.1 mg/ml) treatment. The strain produced two types of emulsifying materials during the growth on hydrocarbons; one was water-soluble extracellular materials and the other was cell wall-associated materials. Both emulsifying materials at lower concentration (0.12%) enhanced the oil-degrading activity of Moraxella sp. K12-7, which had medium emulsifying activity and negative cell hydrophobicity; however, it inhibited the oil-degrading activity of Pseudomunas sp. K12-5, which had medium emulsifying activity and cell hydrophobicity. These results suggest that the oil-degrading activity of Y. lipolytica 180 is closely associated with cell surface structure, and that a finely controlled application of Y.lipolytica 180 in combination with other oil-degrading microorganisms showed a possible enhancing efficiency of oil degradation.

• Journal of Astronomy and Space Sciences
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• v.32 no.4
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• pp.367-377
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• 2015

Atmospheric drag force is an important source of perturbation of Low Earth Orbit (LEO) orbit satellites, and solar activity is a major factor for changes in atmospheric density. In particular, the orbital lifetime of a satellite varies with changes in solar activity, so care must be taken in predicting the remaining orbital lifetime during preparation for post-mission disposal. In this paper, the System Tool Kit (STK$^{(R)}$) Long-term Orbit Propagator is used to analyze the changes in orbital lifetime predictions with respect to solar activity. In addition, the STK$^{(R)}$ Lifetime tool is used to analyze the change in orbital lifetime with respect to solar flux data generation, which is needed for the orbital lifetime calculation, and its control on the drag coefficient control. Analysis showed that the application of the most recent solar flux file within the Lifetime tool gives a predicted trend that is closest to the actual orbit. We also examine the effect of the drag coefficient, by performing a comparative analysis between varying and constant coefficients in terms of solar activity intensities.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.39.1-39.1
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• 2015

Korea has a long history in astronomy, which is proved by many observational records written in Korean chronicles. There are 43 sunspot records in Goryeo dynasty (高麗 918-1392) and 13 records in Joseon dynasty (朝鮮 1392-1910). According to analysis of Korean historical records, it is known that sunspot records in Goryeo dynasty show well in match with the well-known solar activity of 11.3 years. It means that Korean historical sunspot records show real solar phenomena. Korean sunspot records also show that solar activity decrease in Joseon dynasty compared with the previous ~500 years. In order to know the change of solar activity in detail, we examine Korean historical atmospheric records which can indicate climate change. We first analyze historical frost records. Korean chronicles have around 600 frost records during the last millennium. We find that the climate change shows sign of cooling down when check the variation of epoch that the first and last frost events in each year are written. This result is well in accord with that of historical sunspot records. Therefore, we claim that solar activity decrease during the last thousand years.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2749-2753
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• 2009

Structural characteristics that influence on the insecticidal activity ($pI_{50}$) of 2-(n-octyl)isothiourea analogues (1-45) against the diamondback moth (Plutella xylostella, L.) based on three dimensional quantitative structure activity relationships (3D-QSARs) were discussed quantitatively using a comparative molecular field analysis (CoMFA) and a comparative molecular similarity indeces analysis (CoMSIA) methods. The statistical values of the CoMFA 2 model were better than those of the CoMSIA 1 model. The CoMFA 2 model was the optimized model with the correlativity (the training set: Ave. = 0.104 & PRESS = 0.613) and the predictability (the test set: Ave. = 0.086 & PRESS = 0.096). Insecticidal activities with the optimized CoMFA 2 model were dependent upon steric factors (79.4%) of $R_1-R_3$ substituents. From the analytical results of CoMFA contour maps, it is predicted that the R1 substituent of 1-45 which has a steric favor in a broad space, $R_2\;and\;R_3$ groups with a steric favor in a narrow space and a H-bond donor favor would have better the insecticidal activity.

• Journal of Hydrogen and New Energy
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• v.31 no.5
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• pp.444-452
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• 2020

This study investigated the cathode catalyst of direct borohydride/hydrogen peroxide fuel cells for space exploration. Various catalysts such as Au, Ag, and Ni were supported on multiwalled carbon nanotubes (MWCNTs). Various techniques, such as transmission electron microscopy, Brunauer-Emmett-Teller method, scanning electron microscopy, and X-ray diffraction were conducted to investigate the characteristics of the catalysts. Fuel cell tests were performed to evaluate the performance of the catalysts. Ag/MWCNTs exhibited better catalytic activity than the Ni/MWCNTs and better catalytic selectivity of the Au/MWCNTs. Ag/MWCNTs presented good catalytic activity and selectivity even at an elevated operating temperature. The performance of Ag/MWCNTs was also stable for up to 60 minutes.

• Journal of Positioning, Navigation, and Timing
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• v.12 no.4
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• pp.343-348
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• 2023

The ionosphere acts as the largest error source in the Global Navigation Satellite System (GNSS) signal transmission. Ionospheric total electron content (TEC) is also easily affected by changes in the space environment, such as solar activity and geomagnetic storms. In this study, we analyze changes in the regional ionosphere using the Qusai-Zenith Satellite System (QZSS), a regional satellite navigation system. Observations from 9 GNSS stations in South Korea are used for estimating the QZSS TEC. In addition, the performance of QZSS TEC is analyzed with observations from day of year (DOY) 199 to 206, 2023. To verify the performance of our results, we compare the estimated QZSS TEC and CODE Global Ionosphere Map (GIM) at the same location. Our results are in good agreement with the GIM product provided by the CODE over this period, with an averaged difference of approximately 0.1 TECU and a root mean square (RMS) value of 2.89 TECU.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.52.2-52.2
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• 2013

We explore the relative importance of the role of small-scale environment and large-scale environment in triggering nuclear activity of the local galaxies using a volume-limited sample with $M_r$ < -19.5 and 0.02 < z < 0.0685 selected from the Sloan Digital Sky Survey Data Release 7. The active galactic nuclei (AGN) host sample is composed of Type II AGNs identified with flux ratios of narrow emission lines with S/N > 6 and the central velocity dispersion of the sample galaxies is limited to have a narrow range between 130 < ${\sigma}$ < 200($km\;s^{-1}$), corresponding to 7.4 < $log(M_{BH}/M_{\odot})$ < 8.1 in order to fix the mass of the supermassive black hole at the center of its host galaxy. In this study, we find that the AGN fraction ($f_{AGN}$) of late-type galaxies are larger than of early-type galaxies and that for target galaxy with late-type nearest neighbor, $f_{AGN}$ starts to increase as the target galaxy approaches the virial radius of the nearest neighbor (about a few hundred kpc scale). The latter result may support the idea that the hydrodynamic interaction with the nearest neighbor as well as tidal interaction and merger also plays an important role in triggering the nuclear activity of galaxy. We also find that early-type cluster galaxies show decline of AGN activity compared to ones in lower density regions, whereas the direction of dependence of AGN activity for late-type galaxies is opposite.