• Geophysics and Geophysical Exploration
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• v.18 no.2
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• pp.85-90
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• 2015

Orientation corrections for Korean seismic stations were calculated by using ambient noise cross-correlation. This method uses Rayleigh waves extracted from ambient noise cross-correlation instead of teleseismic waveforms from earthquakes, which have been generally used for previous studies. The theoretical background of the method is that the phase of radial-vertical cross-correlation function should be the same as that of $90^{\circ}$ phase-shifted vertical-vertical cross-correlation function. The results calculated from stacked cross-correlograms from Jan. 2007 to Sep. 2008 are comparable to the previous results obtained from teleseismic waveforms. In addition, overall the standard deviations of orientation corrections are less than $5^{\circ}$. The temporal variation in orientation corrections calculated for every 30 days shows no significant change and also standard deviations of them are mostly less than $5^{\circ}$. This means that the orientations of stations used in this study have been kept constant during the period. The sensitivity test for stacking period of the ambient noise cross-correlation method shows that continuous ambient noise record of at least about 30 days is required for estimating reliable orientation corrections.

• Journal of Korean Society of Forest Science
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• v.96 no.2
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• pp.170-177
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• 2007

The objectives of this study were to select early, late, and abundant flowering trees of black locust from domesticated and introduced cultivars, and prediction of flowering period by calculation of accumulated temperature in spring. Four cultivars (Debreceni-2, Pusztavacs, Jaszkiseri, and Rozsaszin AC) from Hungary and a cultivar from Beijing, China, were introduced, propagated by seed and planted in a seed orchard. For domesticated black locust, 63 cultivars from 10 locations throughout the country were selected and propagated by root cutting. Criteria for selection of domesticated cultivars were abundant flowering, long flowering period, or abundant nectar production with, if possible, straight stems. Accumulated temperature was calculated from data of a nearby weather station by accumulating daily maximum temperature minus 5 degree Celsius from January 1 up to the date reaching 880 degrees. Daily mean temperature was also used to calculate accumulated temperature up to the date reaching 450 degrees. The percentages of two-year and three-year-old flowering trees propagated by root cutting were higher than that of trees propagated by seeds, while four-year-old trees all flowered regardless of propagation methods. Among the domesticated cultivars, all the cultivars from Ganghwa showed abundant flowering with highest nectar production of 6.5 ul per flower, which was 100% more than other domesticated cultivars and 50% more than Debreceni-2 cultivar with highest nectar production among the introduced cultivars from Hungary. At the end of the eight years of observations, two trees of Debreceni-2 cultivars and a tree from Beijing, China were selected for early flowering trees which flowered 2 to 3 days earlier than average trees, while a tree of Debeceni-2 and three trees from Bejing were selected for late flowering trees which flowered 2 to 3 days later than average trees. It is possible to extend the flowering period of black locust by 4 to 6 days by planting early and late flowering cultivars together. Abundant flowering trees were unable to be selected due to severe damages by leaf gall midges which killed many trees and reduced the crown size of the remaining trees in the seed orchard, and which were first found in Korea in 2001 and now damaging most of the black locust forests in Korea. The prediction of flowering period by accumulated temperature indicated that black locust flowered to a peak when accumulated daily maximum temperature reached 880 degrees Celsius, and when daily mean temperature reached 450 degrees.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.432-461
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• 1995

The basic principles in the design of Class II amalgam cavity preparations have been modified but not changed in essence over the last 90 years. The early essential principle was "extension for prevention". Most of the modifications have served to reduce the extent of preparation and, thus, increase the conservation of sound tooth structure. A more recent concept relating to conservative Class II cavity preparations involves elimination of occlusal preparation if no carious lesion exists in this area. To evaluate the ideal ClassII cavity preparation design, if carious lesion exists only in the interproximal area, three cavity design conditions were studied: Rodda's conventional cavity, simple proximal box cavity and proximal box cavity with retention grooves. In this study, MO amalgam cavity was prepared on maxillary first premolar. Three dimensional finite element models were made by serial photographic method. Linear, eight and six-nodal, isoparametric brick elements were used for the three dimensional finite element model. The periodontal ligament and alveolar bone surrounding the tooth were excluded in these models. Three types model(B option, Gap option and R option model) were developed. B option model was assumed perfect bonding between the restoration and cavty wall. Gap option model(Gap distance: $2{\mu}m$) was assumed the possibility of play at the interface simulated the lack of real bonding between the amalgam and cavity wall (enamel and dentin). R option model was assumed non-connection between the restoration and cavty wall. A load of 500N was applied vertically at the first node from the lingual slope of the buccal cusp tip. This study analysed the displacement, 1 and 2 direction normal stress and strain with FEM software ABAQUS Version 5.2 and hardware IRIS 4D/310 VGX Work-station. The results were as followed. 1. Rodda's cavity form model showed greater amount of displacement with other two models. 2. The stress and strain were increased on the distal marginal ridge and buccopulpal line angle in Rodda's cavity form model. 3. The stress and strain were increased on the central groove and a part of distal marginal ridge in simple proximal box model and proximal box model with retention grooves. 4. With Gap option, Rodda's cavity form model showed the greatest amount of the stress on distal marginal ridge followed by proximal box model with retention grooves and simple proximal box model in descending order. 5. With Gap option, simple proximal box model showed greater amount of stress on the central groove with proximal box model with retention grooves. 6. Retention grooves in the proximal box played the role of supporting the restorations opposing to loads.

• ALGAE
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• v.35 no.1
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• pp.45-59
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• 2020

To investigate the spatio-temporal distributions of the mixotrophic dinoflagellate Yihiella yeosuensis in Korean coastal waters and its grazing impact on prey populations, water samples were seasonally collected from 28 stations in the East, West, and South Seas of Korea and Jeju Island from April 2015 to October 2018. The abundances of Y. yeosuensis in the water samples were quantified using quantitative real-time polymerase chain reaction (qPCR). Simultaneously, the physical and chemical properties of water from all sampled stations were determined, and the abundances of the optimal prey species of Y. yeosuensis, the prasinophyte Pyramimonas sp. and the cryptophyte Teleaulax amphioxeia, were quantified using qPCR. Y. yeosuensis has a wide distribution, as is reflected by the detection of Y. yeosuensis cells at 23 sampling stations; however, this distribution has a strong seasonality, which is indicated by its detection at 22 stations in summer but only one station in winter. The abundance of Y. yeosuensis was significantly and positively correlated with those of Pyramimonas sp. and T. amphioxeia, as well as with water temperature. The highest abundance of Y. yeosuensis was 48.5 cells mL^-1 in Buan in July 2017, when the abundances of Pyramimonas sp. and T. amphioxeia were 917.6 and 210.4 cells mL^-1, respectively. The growth rate of Y. yeosuensis on Pyramimonas sp., calculated by interpolating the growth rates at the same abundance, was 0.49 d^-1, which is 37% of the maximum growth rate of Y. yeosuensis on Pyramimonas sp. obtained in the laboratory. Therefore, the field abundance of Pyramimonas sp. obtained in the present study can support a moderate positive growth of Y. yeosuensis. The maximum grazing coefficient for Y. yeosuensis on the co-occurring Pyramimonas sp. was 0.42 d^-1, indicating that 35% of the Pyramimonas sp. population were consumed in 1 d. Therefore, the spatio-temporal distribution of Y. yeosuensis in Korean coastal waters may be affected by those of the optimal prey species and water temperature. Moreover, Y. yeosuensis may potentially have considerable grazing impacts on populations of Pyramimonas sp.

• Korean Journal of Ecology and Environment
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• v.40 no.3
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• pp.395-402
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• 2007

Concentrative samplings of 35 times on standing crops of phytoplankton and physicochemical factors were conducted at five sites over Seongsu Bridge to Seongsan Bridge in lower parts of the Ban River from January to December 2006. Over the study, all physicochemical factors showed no large differences among the sampling sites except station 2 having high concentrations of BOD, TN, and TP. Heavy rain also cause these concentrations to decrease. The phytoplankton species and abundance (88 taxa and $1{\sim}41$,104 cells $mL^{-1}$) were varied according to the season, and sharply decreased during heavy rains. In particular, cyanobacteria dominated the phytoplankton community during dry seasons, while green algae and diatom dominated during the rainy seasons. However, after the termination of rain, high water temperatures over $20^{\circ}C$ and low N/P ratios $(9.4{\sim}18.9)$ evoked the cyanobacterial bloom. These results indicate that although the heavy rain (huge outflows of Paltang Dam) temporarily diluted the nutrient level and effected the cyanobacterial bloom in the lower parts of the Han River, cyanobacterial abundance was recovered by the high temperature and low N/P ratio as the rainfall discontinued.

• Korean Journal of Remote Sensing
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• v.26 no.5
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• pp.593-603
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• 2010

Most spatial data acquisition systems employing a set of frame cameras may have suffered from their small fields of view and poor base-distance ratio. These limitations can be significantly reduced by employing an omni-directional camera that is capable of acquiring images in every direction. Bundle Block Adjustment (BBA) is one of the existing georeferencing methods to determine the exterior orientation parameters of two or more images. In this study, by extending the concept of the traditional BBA method, we attempt to develop a mathematical model of BBA for omni-directional images. The proposed mathematical model includes three main parts; observation equations based on the collinearity equations newly derived for omni-directional images, stochastic constraints imposed from GPS/INS data and GCPs. We also report the experimental results from the application of our proposed BBA to the real data obtained mainly in urban areas. With the different combinations of the constraints, we applied four different types of mathematical models. With the type where only GCPs are used as the constraints, the proposed BBA can provide the most accurate results, ${\pm}5cm$ of RMSE in the estimated ground point coordinates. In future, we plan to perform more sophisticated lens calibration for the omni-directional camera to improve the georeferencing accuracy of omni-directional images. These georeferenced omni-directional images can be effectively utilized for city modelling, particularly autonomous texture mapping for realistic street view.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1900-1906
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• 2008

According as zone of life of big city is expanded by new city development etc.., need special skill master plan compensation which can be systematic for wide area traffic problem solution and confusion expense minimization in the metropolitan area because wide area of capital region traffic is gone continuously and continues. Accordingly, Kyonggi Province suggested rapid-transit railway achievement that can connect Seoul Gangnam in 20 minutes with Dongtan new city recently. MLTM(Ministry of Land Transport and Maritime Affaris) announced "Capital region railway network improvement plan research services (2007.12)" result that Gangnam High-speed railway route (Suse $\sim$ Dongtan $\sim$ Pyeongtaek) construction for offer High-speed railway service to capital region and Kyonggi southern part area inhabitantses and need to line capacity tribe solution by Seoul-Busan high-speed railway second-stage and Honam high speed railroad completion. Is judged that need examination about wide area rapid-transit railway combined application operation that take advantage of rail track reserve capacity of High-speed railway for utilization efficiency elevation of country and efficient investment of national finance according as High-speed railway and Gangnam rapid-transit railway route that is suggested in Kyonggi Province are overlaped. Therefore, in this research, I wish to quote investment efficiency plan of railroad business by that different kind's train is run in uniformity track by presenting combined application operation plan and working expenses curtailment effect etc. that is optimized through analysis of roadbed and E & M technology condition, intermediate station plan, train operation planning etc. in case of wide area rapid-transit railway and high-speed railway run combined application.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.434-439
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• 2019

Recently, interest in urban temperature change and ground surface temperature change has been increasing due to weather phenomenon due to global warming, heat island phenomenon caused by urbanization in urban areas. In Korea, weather data such as temperature and precipitation have been collected since 1904. In recent years, there are 96 ASOS stations and 494 AWS weather observation stations. However, in the case of terrestrial networks, terrestrial meteorological data except measurement points are predicted through interpolation because they provide point data for each installation point. In this study, to improve the resolution of ground surface temperature measurement, the surface temperature using satellite image was calculated and its applicability was analyzed. For this purpose, the satellite images of Landsat 8 OLI TIRS were obtained for Seoul Metropolitan City by seasons and transformed to surface temperature by applying NASA equation to the thermal bands. The ground measurement data was based on the temperature data measured by AWS. Since the AWS temperature data is station based point data, interpolation is performed by Kriging interpolation method for comparison with Landsat image. As a result of comparing the satellite image base surface temperature with the AWS temperature data, the temperature difference according to the season was calculated as fall, winter, summer, based on the RMSE value, Spring, in order of applicability of Landsat satellite image. The use of that attribute and AWS support starts at $2.11^{\circ}C$ and RMSE ${\pm}3.84^{\circ}C$, which reflects information from the extended NASA.

• Korean Journal of Environment and Ecology
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• v.35 no.5
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• pp.569-575
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• 2021

This study analyzed the effect of forests on reducing particulate matter by investigating the particulate matter concentration and influencing factors between urban forest and traffic forest. The concentrations of particulate matter in Hongreung Experimental Forest (urban forest) and a forest (traffic forest) formed at the intersection of Cheongryangri Station in Dongdaemun-gu, Seoul were measured with the light scattering method instrument from January to November 2018. During the study period, the average PM₁₀ concentrations in the urban forest and the traffic forest were 12.5㎍/m³ and 15.7 ㎍/m³, respectively, and the average PM_2.5 concentrations were 16.6㎍/m³and 6.9 ㎍/m³, respectively. Comparing the concentration by the urban atmospheric measurement network of the Ministry of Environment and the concentration in urban forests showed that the reduction rate of PM₁₀ was 66.9±28.6% in urbanforest and 58.6±44.1% in traffic forest and that of PM_2.5 was 71.3±23.0% and 64.9±31.3%. The difference in the reduction rate of particulate matter is likely related to the size and structure of the urban forest, and the wind velocity is considered the reduction factor.

• The Journal of the Korea Contents Association
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• v.21 no.4
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• pp.785-794
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• 2021

This study investigated the current status of the design and direction of improvement of the sign system of urban railway stations in the Seoul metropolitan area to see how difficult it is for users to use. As a research method, first, a theoretical study on the literature of the urban railway sign system, second, a survey on the current status of the sign design of the Gimpo Goldline in the Seoul metropolitan area, and third, a survey on the actual use of the sign and problems was conducted. As a result of the current status survey, the location sign is in central alignment with the font of the guide sign, and the guidance sign is in front/back alignment according to the location of the entrance and exit. The background of the font is white and the text is dark black to make it look good to the user. On the other hand, guidance sign is written in white color and background color is gray color. Currently, the Gimpo Urban Railway Guidance Sign System is newly produced and installed, but there is a lack of user design and needs design maintenance that can clearly deliver information to users.