• Atmosphere
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• v.25 no.2
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• pp.309-322
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• 2015

The objective of this study is to evaluate the impact of the high resolution topographies and landuses data on simulated meteorological variables (wind speed at 10 m, temperature at 2 m and relative humidity at 2 m) in WRF. We compare the results with WRF simulation using each resolution of the topographies and landuses, and with 37 AWS observation data on the Seoul metropolitan regions. According to results of using high-resolution topography, WRF model gives better topographical expression over domain. And we can separate more detail (Low intensity residential, high intensity residential, industrial or commercial) using high resolution landuses data. The result shows that simulated temperature and wind speed are generally higher than AWS observation data. However, simulation trend with temperature, wind speed, and relative humidity are similar to observation data. The reason for that is that the high precipitation event occurred in CASE 1 and 2. Temperature have correlation of 0.43~0.47 and standard deviation of $2.12{\sim}2.28^{\circ}C$ in CASE 1, while correlation of more than 0.8 and standard deviation of $3.05{\sim}3.18m\;s^{-1}$ in CASE 2. In case of wind speed, correlation have lower than 0.5 and Standard Deviation of $1.88{\sim}2.34m\;s^{-1}$ in CASE 1 and 2. In statistical analysis shows that using highest resolution (U01) results are more close to the AWS observation data. It can be concluded that the topographies and landuses are important factor that affect model simulation. However, the tendency to always use high resolution topographies and landuses data appears to be unjustified, and optimal solution depends on the combination of scale effect and mechanisms of dynamic models.

• The Journal of the Korea Contents Association
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• v.15 no.6
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• pp.539-546
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• 2015

In this study, we develop numerical model using the elliptic mild-slope equation for waves propagating around axis-symmetric topographies where the water depth varies arbitrarily having zero at the coastline. The entire region is divided into three regions. In the both of inner and outer regions, an existing analytical solutions are used. In the middle region, the finite element technique is applied to the governing equation. To get the solution, the methods of separation of variables, Frobenius series are used. Developed solution is validated by comparing with previously developed analytical solution. We also investigate various cases with different bottom topographies.

• Journal of Korea Water Resources Association
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• v.33 no.6
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• pp.805-814
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• 2000

A numerical model based on the boundary element method is employed to describe diffraction of monochromatic water waves due to varying topographies. The model is firstly verified by comparing obtained reflection and transmission coefficients of waves over a trench to those of the eigenfunction expansion method. The model is then used to investigate the Bragg reflection of waves over sinusoidally varying topographies. Calculated reflection coefficients are compared to available laboratory measurements and semi-theoretical results. A reasonably good agreement is observed.served.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.13 no.3
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• pp.189-194
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• 2001

The present study describes the Bragg reflection of monochromatic water waves propagating over a train of doubly-sinusoidally varying topographies. A numerical model based on the boundary element method is firstly verified by calculating reflection and transmission coefficients of waves over a trench. Calculated solutions are compared with those of the eigenfunction expansion method. The model is then used to simulated reflection of monochromatic water waves propagating over doubly-sinusoidally varying bottom topographies. Obtained reflection coefficients are compared with those of available laboratory measurements, those of the eigenfunction expansion method and the extended mild-slope equation. A reasonable agreement is shown.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.2
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• pp.147-152
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• 2010

The investigations were conducted to improve the fertilizer use in upland soil on the different topographies, and crops at 163 upland fields located in the parts of Gyengsangbuk-do area. The soil distribution was based on crops, and topographiese. Soils from these fields were analyzed for pH, organic mater, available phosphorus ($P_2O_5$), exchangeable potassium, calcium and magnesium, and found to have pH5.9, organic mater 23.2 g $kg^{-1}$, $P_2O_5$ 549 mg $kg^{-1}$, exchangeable potassium, calcium and magnesium were 0.9, 5.6, and 2.3 $cmol^+\;kg^{-1}$, respectively. The excessive distribution percent of soil samples for crops were higher than the optimum range in $P_2O_5$, and exchangeable potassium. The content of organic matter, $P_2O_5$, exchangeable potassium, calcium, and magnesium were increased with the decreasing slope. The major chemical components in fans topographies were 28.4 g $kg^{-1}$ for organic matter, 700 mg $kg^{-1}$ for $P_2O_5$, and 1.0 $cmol_c\;kg^{-1}$ for exchangeable potassium relatively higher in comparison with other topographies. The content of $P_2O_5$ were lower in diluvium, and hilly areas than other topographies. The soil of red pepper was more influenced by the amount of applied fertility than the slope, and topographies, On the other hand the crops like soybean and sesame, were more affected by the slope, and topographies.

• Journal of The Geomorphological Association of Korea
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• v.20 no.3
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• pp.65-77
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• 2013

This study investigated and analyzed the topographic landscape resources of Mureung Valley in Donghae-si from the viewpoint of geotourism in order to suggest the tourism contents and tour course. A total of 29 topographic landscapes were observed; these are broadly divided into 4 features including weathering landform, mountainous landform, fluvial landform, and structural landform. Major topographies are fluvial landform (13) and weathering landform (12). At least 19 topographies (14 sites, 19 topographic landscapes) are currently used as tourism resources, with 10 topographies having potential to be developed as new tourism resources. The 10 topographic landscapes are as follows: (1) Jamryong Bawi (Hidden Dragon Rock), (2) Janggipan Bawi (Korean Chessboard Rock), (3) Nurungji Bawi (Parched Rice Rock), (4) Damjang Bawi (Fence Rock), (5) Gyedan Bawi (Stairs Rock), (6) Heundeul Bawi (Rocking Rock), (7) Jeopsi Bawi (Dish Rock), (8) Dol Umul (Stone Well), (9) Jogak Bawi (Carved Rock), and (10) Dubu Bawi (Topu Rock). The topographic tour course can be divided into 3 routes considering accessibility and time. Route 1 is a basic one that anyone can easily use; Route 2 and 3 can be used by visitors who have more time to spare or who are more active.

• Journal of Korean Society of Forest Science
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• v.64 no.1
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• pp.42-46
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• 1984

This study was carried out to obtain the advanced basic data for hillside erosion control works. Recovery of vegetation in the hillside erosion control districts depends on various factors i.e., topographies, soil qualities, rain conditions and erosion control methods. The only relations between topographies and vegetation coverage were surveyed, since the other factors were equal in all those surveyed areas. The results obtained are summarized as follows; 1) Mean coverage values were decreased in order of 80%, 78.7%, 64.0% and 56.5%r in concave slope, uniform slope, compound slope and convex slope respectively. The mean coverage of all aspects was 69.8%. The slope pattern have a influence on formation of coverage. 2) Moisture ratio in soil and mean slope have an effect on the mean coverage value. 3) In the beginning of the hillside erosion control working, coverage (14.8%) by arbor species was too low comparing with that by herb. 4) It is more desirable to recover regetation by artificial planting or seed planting than by the natural vegetation in the barren hillside. In the beginning of the hillside erosion control working, it is difficult to expect vegetation recovery by natural species.

• Geomechanics and Engineering
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• v.30 no.1
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• pp.1-10
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• 2022

Seismic ground response evaluation is one of the main issues in geotechnical earthquake engineering. These analyses are subsequently divided into one-, two- and three-dimensional methods, and each of which can perform in time or frequency domain. In this study, a novel approach is proposed to assess the seismic site response using two-dimensional transfer functions in frequency domain analysis. Using the proposed formulation, a program is written in MATLAB environment and then promoted utilizing the equivalent linear approach. The accuracy of the written program is evaluated by comparing the obtained results with those of actual recorded data in the Gilroy region during Loma Prieta (1989) and Coyote Lake (1979) earthquakes. In order to precise comparison, acceleration time histories, Fourier amplitude spectra and acceleration response spectra diagrams of calculated and recorded data are presented. The proposed 2D transfer function diagrams are also obtained using mentioned earthquakes which show the amount of amplification or attenuation of the input motion at different frequencies while passing through the soil layer. The results of the proposed method confirm its accuracy and efficiency to evaluate ground motion during earthquakes using two-dimensional model. Then, studies on irregular topographies are carried out, and diagrams of amplification factors are shown.

• Journal of the Korean earth science society
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• v.43 no.4
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• pp.481-489
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• 2022

Various types of karst topographies are found worldwide. Owing to their global distribution, karst areas have been extensively studied by scientists who investigate new discoveries by linking the characteristics of karst topographies with their own research fields. However, there have been only a few studies on karsts in the Republic of Korea, and little research exists on their hydrogeology. Fragmentary studies have been conducted on the hydrochemical characteristics of groundwater in limestone areas, the causes of high arsenic concentrations in groundwater, and the hydraulic conductivity of limestone areas. Research on hydrogeological characterization and flow mechanisms in these areas has only began recently. Identification and the proper management of available groundwater resources in karst (limestone) areas is essential as their unique geological characteristics render it difficult to construct reservoirs or dams at appropriate scales. We have reviewed prior work on karsts in the Republic of Korea to provide information that supports water resource security in the karst areas, to improve the understanding of the equitable use of water resources, and to identify the best management practices for groundwater resource resilience improvement.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4B
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• pp.413-419
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• 2008

In this study, we develop analytical solutions for long waves propagating over several types of axis-symmetric topographies where the water depth varies in an arbitrary power of radial distance. The first type is a cylindrical island mounted on a shoal. The second type is a circular island. To get the solution, the methods of separation of variables, Taylor series expansion and Frobenius series are used. Developed analytical solutions are validated by comparing with previously developed analytical solutions. We also investigate various cases with different incident wave periods, radii of the shoal, and the powers of radial distance.