• Journal of Astronomy and Space Sciences
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• v.33 no.3
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• pp.185-196
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• 2016

New multiband BVRI light curves of NSVS 1461538 were obtained as a byproduct during the photometric observations of our program star PV Cas for three years from 2011 to 2013. The light curves indicate characteristics of a typical W-subtype W UMa eclipsing system, displaying a flat bottom at primary eclipse and the O'Connell effect, rather than those of an Algol/b Lyrae eclipsing variable classified by the northern sky variability survey (NSVS). A total of 35 times of minimum lights were determined from our observations (20 timings) and the SuperWASP measurements (15 ones). A period study with all the timings shows that the orbital period may vary in a sinusoidal manner with a period of about 5.6 yr and a small semi-amplitude of about 0.008 day. The cyclical period variation can be interpreted as a light-time effect due to a tertiary body with a minimum mass of 0.71 M_⊙. Simultaneous analysis of the multiband light curves using the 2003 version of the Wilson-Devinney binary model shows that NSVS 1461538 is a genuine W-subtype W UMa contact binary with the hotter primary component being less massive and the system shows a low mass ratio of q(m_c/m_h)=3.51, a high orbital inclination of 88.7°, a moderate fill-out factor of 30 %, and a temperature difference of ΔT=412 K. The O'Connell effect can be similarly explained by cool spots on either the hotter primary star or the cool secondary star. A small third-light corresponding to about 5 % and 2 % of the total systemic light in the B and V bandpasses, respectively, supports the third-body hypothesis proposed by the period study. Preliminary absolute dimensions of the system were derived and used to look into its evolutionary status with other W UMa binaries in the mass-radius and mass-luminosity diagrams. A possible evolution scenario of the system was also discussed in the context of the mass vs mass ratio diagram.

• Journal of Korea Water Resources Association
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• v.40 no.7
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• pp.571-583
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• 2007

The effects of climatic changes owing to urbanization, geographical and topographical conditions on Penman-Monteith reference evapotranspiration, and energy and aerodynamic terms of Penman-Monteith reference evapotranspiration have been studied. In this study, 56 climatological stations including the Seoul metropolis in South Korea have been selected, and the area of study site was set at $314\;km^2$. The climatological station is centrally located In the study area with a 10 km radius. The geographical and topographical characteristics of these sites were examined using GIS analysis. Land use status of the study area was also examined to estimate the extent of urbanization. The study results indicated that the variation of reference evapotranspiration rate is closely related to urbanization in most climatological stations. The level of change in reference evapotranspiration was higher in areas with higher urbanization rates. The change in reference evapotranspiration appears to be caused by temperature rises following heat island phenomena due to urbanization, and by the decrease in humidity, wind speed and sunshine duration due to the Increase in residential areas in urban districts. Especially, the humidity decrease causes a significant decrease in evapotranspiration rate. The study results showed that climatic change due to urbanization and proximity to the coast had the greatest effect on reference evapotranspiration.

• Economic and Environmental Geology
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• v.49 no.4
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• pp.269-280
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• 2016

I presented three vector crustal magnetic anomaly components and six gradients by using spherical Slepian functions over the cap area of $20^{\circ}$ of radius centered on the South Pole. The Swarm mission, launched by European Space Agency(ESA) in November of 2013, was planned to put three satellites into the low-Earth orbits, two in parallel in East-West direction and one in cross-over of the higher altitude. This orbit configuration will make the gradient measurements possible in North-South direction, vertical direction, as well as E-W direction. The gravity satellites, such as GRACE and GOCE, have already implemented their gradient measurements for recovering the accurate gravity of the Earth and its temporal variation due to mass changes on the subsurface. However, the magnetic gradients have little been applied since Swarm launched. A localized magnetic modeling method is useful in taking an account for a region where data availability was limited or of interest was special. In particular, computation to get the localized solutions is much more efficient and it has an advantage of presenting high frequency anomaly features with numbers of solutions fewer than the global ones. Besides, these localized basis functions that were done by a linear transformation of the spherical harmonic functions, are orthogonal so that they can be used for power spectrum analysis by transforming the global spherical harmonic coefficients. I anticipate in scientific and technical progress in the localized modeling with the gradient measurements from Swarm and here will do discussion on the results of the localized solution to represent the three vector and six gradient anomalies over the Antarctic area from the synthetic data derived from a global solution of the spherical harmonics for the crustal magnetic anomalies of Swarm measurements.

• Korean Journal of Construction Engineering and Management
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• v.22 no.1
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• pp.27-35
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• 2021

The study intends to identify the effects of infrastructure property on an apartment house by analyzing the price variation affected by factors constituting the quality of the transit services of each individual station in urban railway system based on hedonic price model. The research findings indicate that the prices depending on the transit users have increased from 7.8% to 12.2% in Seoul and decreased from 6.1% to 12.9% in Gyeonggi, which implies that a lower number of transfer users has a positive effect on housing prices in Seoul unlike Gyeonggi. It also is noteworthy that the distance to the urban railway station had a negative effect on housing prices in Seoul and positive effect in Gyeonggi. Taking these results together, in Seoul, the increase in the number of transit users had a negative effect on neighborhood housing prices. When analyzed by segments, however, an additional negative effect was observed only in the apartments located within the radius of 100 meters. It is also found that the impact of transit users varies according to the regional characteristics, such as the density of commercial facilities and the population density, and the spatial extent of negative effect also showed regional differences. These results provide implications for the planning of new stations, new cities, and land use of existing areas around stations.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.5
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• pp.8-18
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• 2012

Urban nature plays an important role not only in the improvement of the physical environment but also from the perspective of psychological and social function. In particular, schoolyards as well as the green spaces near school surroundings function as a primary space for urban children to experience nature in Korea, as they spend most of their time at school. In this study, the status of urban green spaces near school surroundings was examined. For the analysis, 185 elementary schools in Seoul were selected and the green spaces within a radius of 300m(defined as 'school zone' in this study) were analyzed using the Rapid Eye multispectral satellite image data. The mean green space ratio of school zone accounts to about 21% with a high variation from 74% to 0.7% and more than half of the school zone have a green space ratio of less than 20%. Schools with a high green space ratio in their school zone are mostly located near urban forests, so forest areas particularly contribute to increase the green space ratio. Furthermore, forest vegetation shows relatively higher vitality than other green spaces located in urbanized areas. In contrast, schools with a low green space ratio in their school zone are mostly situated in high-density residential areas and the green spaces show relatively low vegetation vitality. Except for the urban forest, the majority of urban green spaces in urbanized areas are landscape green facilities in apartment districts. The other types of urban open spaces such as environmentally shaped schoolyards or street parks account only for a very small proportion of school surroundings. Therefore, it is needed to establish countermeasures in the context of urban planning; e.g. to promote the school forest projects preferentially by selecting schools with a extremely low green space ratio in their school zone, to foster roof greening in near surroundings, and to connect schoolyards organically with nearby apartment landscape green facilities as an easily accessible urban open space.

• Journal of Bio-Environment Control
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• v.16 no.3
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• pp.210-216
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• 2007

A study was conducted to find mechanism and spray characteristics of a mini-sprinkler with downward spray to develop a new design type to be able to prevent drop water. The experiments were executed in a plastic greenhouse to minimize the effect of the wind. Data was collected at five different operation pressures and at 4 different raiser heights. Spray characteristics of the sprinkler such as effective radius, effective area, mean application depth, absolute maximum application depth, effective maximum application depth and coefficient of variation were determined. In order to analyze the mechanism and packing supporter of sprinkler, the numerical simulation using ABAQUS was performed. The optimum pressure for preventing drop water was determined.