• Ocean and Polar Research
• /
• v.36 no.1
• /
• pp.1-12
• /
• 2014

This study investigates spatial and temporal variations in the generation and propagation of internal tides around the Korea Strait using a three-dimensional high resolution model (Regional Ocean Modeling System; ROMS). The model results were verified through comparison with in-situ current measurements from an array of 12 acoustic Doppler current profilers (ADCPs) deployed in the Korea Strait. Fluxes and distributions of internal tidal energy were calculated using simulation results gathered in February and August. Our analyses reveal that energetic semidiurnal internal tides are generated in a region around the Korea Strait shelf break ($35.5^{\circ}N$, $130^{\circ}{\sim}130.5^{\circ}E$), where the strong cross-slope semidiurnal barotropic tidal currents interact with a sudden topographical change. The semidiurnal internal tidal energy generated in summer displays values about twice as large as values in winter. Propagation of semidiurnal internal tides also reveals seasonal variability. In February, most of the semidiurnal internal tides propagate only into the open basin of the East Sea due to weak stratification in the Korea Strait, which inhibits their southwestward propagation. In August, they propagate southwestward to $35.2^{\circ}N$ along the western channel of the Korea Strait because of strong stratification. In addition, semidiurnal internal tides generated in a region west of Tsushima Island are found to propagate to the coast of Busan. This can be explained by the intensified stratification due to the strong intrusion of bottom cold water in the western channel of the Korea Strait during summer.

• Water for future
• /
• v.27 no.4
• /
• pp.85-94
• /
• 1994

A Sensitivity analysis on the model parameters involved in the Clark watershed routing method is made to demonstrate the effect of each parameter on the magnitude of 50-year design flood for small urban streams. As for the rainfall parameter the time distribution pattern of design storm was selected. For short duration storms Huff, Yen & Chow and Japanese Central type distributions were selected and the Mononobe distribution of 24-hour design storm was also selected and tested for Clark method application. The effect of SCS runoff curve number for effective rainfall and the methods of subbasin division for time-area curve were also tested. The routing parameter, i.e. the storage constant(K), was found to be the dominating parameter once design storm is selected. A multiple regression formula for K correlated with the drainage area and main channel slope of the basin is proposed for the use in urban stream practice for the determination of design flood by Clark method.

• Journal of Korea Water Resources Association
• /
• v.38 no.9 s.158
• /
• pp.699-711
• /
• 2005

In this study, the U.S. Geological Survey's DR3M-II(Distributed Routing Rainfall-Runoff Model) was applied for small urban drainage. DR3M-II is a watershed model for routing storm runoff through a branched system of pipes and natural channels using rainfall input. The model was calibrated and verified using short term rainfall-runoff data collected from Sanbon basin. Also, the parameters were optimized using Rosenbrock technic. An estimated simulation error for peak discharge was about 7.4 percent and the result was quite acceptable. Results of the sensitivity analysis indicate that the percent of effective impervious area and ${\alpha}$ defining surface slope and roughness were the most sensitive variables affecting runoff volumes and peak discharge for low and high intensity storm respectively. In most cases, soil moisture accounting and infiltration parameters are the variables that give more effects to runoff volumes than peak discharge. Parameter ${\alpha}$ showed the opposite result.

• Journal of the Korean Geographical Society
• /
• v.41 no.6 s.117
• /
• pp.670-681
• /
• 2006

The purpose of this study is to clarify the behavior of subsurface water flow during rainfall on the hillslope in the Dongguneung experimental basin. As a result of the study, the following conclusions were obtained. Under the total rainfall of 20mm, there were no groundwater level changes. However, it was found that total rainfall amount and rainfall intensity were important factors to change groundwater level in hilly slope. Also the rainfall duration and preexisted rainfall amount were important factors to change it on the head hollow. To analyze the modification of 'U-shaped Gol' landform, the pattern of return flow and through flow have to check during storm events. The microgeomorphic change of head hollow is based on the pattern of subsurface water flow.

• Proceeding of Spring/Autumn Annual Conference of KHA
• /
• 2008.11a
• /
• pp.322-326
• /
• 2008

Due to the rapid increasing in the aged population, it calls for social countermeasures urgently. Especially, there are increasing needs of space environment to support physical and spiritual characteristics of elderly. When designing space environment including house, there are growing consideration for elderly and extending appreciation of aging. The purpose of this study is to investigate the perception on environment planning for the seniors among university students who majoring in Housing & Interior Design and who visited the Aging Simulation Center located in Seoul. The Aging Simulation Center gives a chance of space design to support the elderly based on the experiences of daily living for the designers who design environment for elderly. Questionnaire survey was conducted to obtain data from 93 university students in their 20s majoring in housing and interior design who visited the Aging Simulation Center. The research findings showed that the recognition for design elements of residential environment for the elderly of respondents was changed toward positive way after visiting the Aging Simulation Center. The Aging Simulation Center was an effective educational environment for the preliminary designers to understand aging and the importance of appropriate design for users' needs. That is, aging simulation space can improve recognition of necessity of universally designed environment to support the elderly. Handrails around bathtub and wash basin, stair slope, electric auto-level controlled kitchen counter and kitchen cabinet were especially perceived for the respondents as very essential design elements to support the aged.

• The Journal of the Petrological Society of Korea
• /
• v.5 no.1
• /
• pp.84-88
• /
• 1996

Pb isotope composition is analyzed from the rock chips of marbles intercalated between gneisses of Muju area and it shows very large variation ($^{206}Pb/^{204}Pb$=23.74~4142, $^{207}Pb/^{204}Pb$=16.32~18.43, $^{208}Pb/^{204}Pb$=36.42~39.75). The data points form well defined positive relationship on $^{206}Pb/^{204}Pb$ vs $^{207}Pb/^{204}Pb$ plot, which corresponds to $1.99{\pm}0.10$($2{\sigma}$) Ga. This age is very similar to the formation ages of the granitic gneisses from Buncheon and Cheondongri (Tanyang), and suggests that the fairly large volume of Sobaeksan Massif suffered regional metamorphism at this time. It is suggested that the most parts of Korean peninsula including Kyeonggi and Sobaeksan Massifs were very close each other and experienced a regional metamorphism together about 2.0 Ga ago from the fact that galenas from whole Korean Peninsula except Kyeongsang Basin and metamorphic rocks from Kyeonggi Massif also reveal a similar slope corresponding 2.0 Ga on Pb-Pb isotope plot.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.17 no.6
• /
• pp.1-15
• /
• 2014

A dredging on erosion control dam has been enforced without evaluation the factors that affect the dredging. In addition, there is the negative effect much more than positive effect by dredging on erosion control dam. Therefore, this study was carried out to develop evaluation indicators and to suggest fieldbook in order to determine whether sand deposits at erosion control dam should be dredged up or not. The most important six evaluation indicators that can decide to dredge up at erosion control dam were obtained from three round delphi technique and were selected in the following order: the current sand deposit ratio(0.339), existence of cultivated land and house downstream(0.276), the slope of streambed(0.162), the amount of movable soil and gravel(0.118), the history of any disasters(0.063), the basin area(0.043). The weighted score for each evaluation indicator were acquired from AHP analysis with respect to the degree of importance and then the modified weighted score for actual measurements were classified as three categories: large(2.53), medium(1.60) and small(1.01). Based on delphi technique, erosion control dam dredging evaluation fieldbook introduced the four evaluation indicators out of the total six evaluation indicators and two low effected evaluation indicators were excluded. This results showed that the values for reliability analysis and consistency ratio were acceptable.

• Journal of Korea Water Resources Association
• /
• v.47 no.2
• /
• pp.207-221
• /
• 2014

Recently, due to global warming, climate change has affected short time concentrated local rain and unexpected heavy rain which is increasingly causing life and property damage. Therefore, this paper studies the characteristic of localized heavy rain and flash flood in Nakdong basin study area by applying Data Mining method to predict flood and constructing water level predicting model. For the verification neural network from Data Mining method and hydraulic flood routing was used for flood from July 1989 to September 1999 in Nakdong point and Iseon point was used to compare flood level change between observed water level and SAM (Slope Area Method). In this research, the study area was divided into three cases in which each point's flood discharge, water level was considered to construct the model for hydraulic flood routing and neural network based on artificial intelligence which can be made from simple input data used for comparison analysis and comparison evaluation according to actual water level and from the model.

• Journal of the Korean Geographical Society
• /
• v.44 no.4
• /
• pp.429-446
• /
• 2009

To understand the sulfur flux and cycle in the forest catchment, the hydrological processes and chemical variation of soil solution, groundwater and stream water were analyzed at the Matsuzawa catchment located in the Kiryu Experimental Basin, Shiga Prefecture, central Japan. Unsaturated soil layer at the upper slope of catchment was the source area of ${SO_4}^{2-}$, and deep soil layer and groundwater were the sink zone of ${SO_4}^{2-}$. The vertical distribution of ${SO_4}^{2-}$ concentrations in groundwater affected seasonal variation of ${SO_4}^{2-}$ concentrations in stream water, as groundwater level changed. It is reasonable to assume that each hydrological processes in the forest catchment play an important roles in the retention and discharge of ${SO_4}^{2-}$.

• Journal of Korea Water Resources Association
• /
• v.38 no.12 s.161
• /
• pp.1021-1028
• /
• 2005

This study purpose to develop simulation model of optimal design condition of urban storm sewer system considering risk. Urban Storm Sewer Optimal Design Model(USSOD) can compute pipe capacity, pipe slope, crown elevation, excavation depth, risk and return cost in the condition of design discharge. Rational formula is adopted for design discharge and Manning's formula is used for pipe capacity. Discrete differential dynamic programming(DDDP) technique which is a kind of dynamic programming(DP) is used for optimization and first order second moment approximation method and uncertainty analysis is also for developing model. USSOD is applied to hypothetical drainage basin to test and verify, which resulted economical and efficient design in urban drainage sewer system.