• Tunnel and Underground Space
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• v.19 no.5
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• pp.432-439
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• 2009

For more reliable estimation of seismic source, attenuation properties and dynamic ground property, site amplification function should be considered. Among various estimation methods, this study used the Nakamura's method (1989) for estimating site amplification characteristics. This method was originally applied to the surface waves of background noise and therefore there are some limitations in applying to general wave energy. However, recently this method has been extended and applied to the S wave energy successfully. This study applied the method to S wave and Coda wave energy, which is equivalent to the backscattered S wave energy. We used more than 60 observed ground motions from 5 earthquakes which were occurred recently, with magnitude range from 3.6 to 5.1. Each station showed characteristic site amplification property in low-, high- and resonance frequencies. Some of the stations showed as high as 4 times of site amplification in the range of specific frequencies, which may imply abnormal small scale geologic strata below the station or development of various trapped modes in the basin structure. Moreover, removal of site amplification can give us more reliable seismic source and attenuation parameters, addition to the seismic hazard estimation.

• The Journal of the Petrological Society of Korea
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• v.14 no.4 s.42
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• pp.226-236
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• 2005

Using the concept of granite suite/supersuite we hierarchically divided the Triassic granites in South Korea which have spatio-temporally close relationships each other. Among the Triassic granites in the Okcheon belt (western Yeongnam massif), the Baegrok granite and the Jeomchon granite can be grouped into one suite, the Baegrok suite, whereas the Cheongsan granite into the Cheongsan suite. These two suites can be grouped again into a larger supersuite, the Baegrok supersuite, on the basis of the similarity in the source rocks and the contrasts in the petrographic and geochemical characteristics. Three Triassic granites in the Gyeongsang basin - the Yeongdeok granite, the Yeonghae granite, and the Cheongsong granite - can be grouped into the Yeongdeok suite, Yeonghae suite and Cheongsong suite, respectively. These three suites can be grouped again into a larger supersuite, the Yeongdeok supersuite, on the basis of the similarity in the source rocks and the contrasts in the petrographic and geochemical characteristics. Nd-Sr isotopic signatures for the Baegrok supersuite are quite distinct from those for the Yeongdeok supersuite, indicating that the source materials of each granitic magma were not identical. The source rocks for the Baegrok supersuite are thought to be a mixture of two crustal components of the Yeongnam massif, whereas those for the Yeongdeok supersuite to be a mixture of the depleted mantle with the crustal components of the Yeongnam massif. The fact that the two contemporaneous granite supersuites were derived from the different sources can be explained by the difference of the tectonic environments where the granitic magmas were produced.

• Magazine of the Korean Society of Agricultural Engineers
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• v.16 no.2
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• pp.3438-3453
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• 1974

Unmeasured value of water for human lives is widely approved, but the water as one of natural resources cannot be evaluated with ease since it changes itself ceaselessly by flowing-out or transforming the phase. Major objectives of the study concerned consequently with investigating its potentiality and evaluating its time seriesly availabity in a volumatic unit. And the study was performed to give the accurate original data to the planners concerned. Some developed rational methods of predicting runoff related to hydrological factors as precipitation, were to be discusseed for their theorical background and to be introduced whether they needed some corrections or not, comparing their estimation with actual runoff from synthetic unit-hydrograph methods. To do so, the study was performed to select Kongju Station, located at the watershed of the Keum River, and to collect such hydrological data from 1962 to 1972 as runoff, water level, precipitation, and so on. On the other hand, the hydrological characteristics of runoff were concluded more reasonably in numerical values, with calculating the the ratio of daily runoff to annual discharge of the flow in percentage, as. the distribution ratio of runoff. The results of the study can be summarized as follows; (1) There needed some consideration to apply the Kajiyama's Formula for predicting monthly runoff of rivers in Korea.(2) The rational methods of predicting runoff might be recommended to become less theorical and reliable than the unique analyzation of data concerned in each given water basin. The results from the Keum River prepared above would be available to any programms concerned. (3) The most accurate estimation for runoff could be suggested to synthetic unithydrograph methods calculated from the relation between each storm and runoff. However it was not contained in the study. (4) The relations between rainfall and runoff at KongJu Station were as following table. The table showed some intersting implications about the characteristics of runoff at site, which indicated that the runoff during three months from July to September approached total of 60% of quantity while precipitation concentrated on the other three from June to August. And there were some months which had more amount of runoff than expected values calculated from the precipitation, such as Febrary, March, August, September, Octover, and December, shown in the table. Such implications should be suggested to meet any correction factors in the future formulation concerned with the subjects, if any rational methods would be required.

• Journal of the Korean Society of Hazard Mitigation
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• v.6 no.4 s.23
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• pp.37-47
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• 2006

Urban development results in increased runoff volume and flowrates and shortening in time of concentration, which may cause frequent flooding downstream. Flow retardation structures to limit adverse downstream effects of urban storm runoff are used. There are various types of flow retardation measures include detention basins, retention basins, and infiltration basins. In basic planning phase, a number of planning models of detention ponds which decide storage volume by putting main variables were used to design detention ponds. The characteristics of hydrological parameters $\alpha,\;\gamma$ which are used in planning models of detention pond were analyzed. In this study, detention ponds data of Disaster Impact Assessment report at 22 sites were analyzed in order to investigate correlation between characteristic of urban drainage basin parameter and characteristics of detention pond parameter due to urbanization effects. The results showed that storage volume was influenced by peak discharge ratio $\alpha$ more than runoff coefficient ratio $\beta$ and peak discharge ratio $\alpha$ was influenced by runoff coefficient ratio $\beta$ less than regional parameter n. Storage ratio was mainly influenced by duration of design rainfall in the case of trapezoidal inflow hydrograph such as Donahue et al. method.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.57-62
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• 2006

Busan New Port, under construction aiming for the hub of Northeast Asia and Partly in operation, had damaged up to 48 billion Won due to Typhoon 'maemi' in 2003. The present criteria of domestic harbor design only describes about the critical wave height with respect to the size of vessel for harbor tranquility. The berth operation ratio which represents the annual available berthing days is depending on the efficiency of cargo handling work and this depends on the motion of the moored vessel due to the wave action and the characteristics of cargo gears. The motion of moored vessel might be related not only to the wave height but also to wave period. Furthermore, the berth operation ratio relies on external forces such as currents and winds, including the characteristics of mooring system and the specification of the moored vessel. In this study we only deal with berth operation ratio in normal sea state, considering wave and current by measured data and numerical calculation. Especially we tried to evaluate the berth operation ratio for each berth adopting the variation of dredging and reclamation plan and the change of wave environment during the process of the new port construction. For better understanding and analysis of wave transformation process, we applied the steady state spectral wave model and extended mild-slope wave model to the related site. This study summarizes comparisons of harbor responses predicted by two numerical predictions obtained at Busan New port site. Field and numerical model analysis was conducted for the original port plan and the final corrected plan.

• Korean Journal of Remote Sensing
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• v.14 no.2
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• pp.117-128
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• 1998

Topex/Poseidon satellite, launched in Auguest 1992, has provided more 5 years of very good quality data. Efficient improvements, either about instrumental accuracy or about sea level data correction, have been made so that Topex/Poseidon has become presently a wonderful tool for many researchers. The first mission data of 73 cycles, September 1992 - August 1994, was used to our study in order to know characteristics of environmental correction factors in the Amsterdam-Crozet-Kerguelen region of the South Indian Ocean. According to standard procedures as defined under user handbook for sea surface height data processes, then we have chosen cycles 43 as the cycle of reference because this cycle has provided the completed data for measurement points and has presented the exacted position of ground track compared to another cycles. It was computed variations of various factors for correction in ascending ground track 103(Amsterdam-Kerguelen continental plateau) and descending ground track170 (Crozet basin). Here the variations of ionosphere, dry troposphere, humid troposphere, electromagnetic bias, elastic tide and loading tide were generally very smaller as a few of cm, but the variations of oceanic tide(30-35cm) and inverted barometer(15-30cm) were higher than another factors. For the correction of ocean tide, our model(CEFMO: Code d' Elements Finis pour la Maree Oceanique) - This is hydrodynamic model that is very well applicated in all oceanic situations - was used because this model has especially good solution in the coastal and island area as the open sea area. Conclusionally, it should be understood that the variation of ocean free surface is mainly under the influence of tides(>80-90%) in the Amsterdam - Crozet- Kerguelen region of the South Indian Ocean.

• The Journal of the Petrological Society of Korea
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• v.13 no.2
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• pp.47-63
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• 2004

This study focuses on the petrography and petrochemical characteristics of the volcanic and plutonic rocks in Gadeog island, Busan, Korea. Based on textural and mineralogical characteristics, intermediate volcanic rocks can be divided into andesitic lava flows (porphyritic and massive andesites) and andesitic pyroclastics. Felsic volcanic rocks are composed of rhyolite, rhyolitic welded tuff, and tuff breccia. Plutonic rocks are intruded rhyolite and andesitic rocks, and composed of hornblende granodiorite which contains lots of mafic magma enclaves. Volcanic rocks are composed of andesite, dacite and rhyolite having a range in SiO$_2$ from 59 to 78wt.%. The volcanic rocks belong to the calc-alkaline rock series. Plutonic rocks have a range in SiO$_2$ from 63 to 69wt.%. This compositional variations correspond to those of Cretaceous volcanic and plutonic rocks in the southeastern Gyeongsang basin. The trace element composition and rare earth element patterns of the volcanics, which are characterized by high LREE/HFSE ratios and enrichment in LREE, suggest that they are typical of calc-alkaline volcanic rocks produced in the subduction environment around continental arc. We concluded that volcanic and plutonic rocks in Gadeog Island were evolved from orogenic andesitic magma which was produced by partial melting of the mantle wedge in the subduction environment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.6
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• pp.793-800
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• 2018

It is necessary to determine an optimal design frequency for establishing stable flood control against frequent flood disasters. Depending on the importance of river and regional characteristics, design return periods are suggested from at least 50 years up to 200 years for river design. However, due to the wide range of applications, it is not desirable to reflect the geographical and flood control characteristics of river. In this study, Bayes theory was applied to seven evaluation factors to determine the optimal design return period of rivers in Chungcheongnam-do; urbanization flooded area, watershed area, basin coefficient, slope, water system and stream order, range of backwater effect, abnormal rainfall occurrence frequency. The potential flood damage (PFD) capacity was estimated considering climate change and the appropriate design return period was determined by analyzing the capacity of each district. We compared the design return periods of 382 rivers in Chungcheongnam-do with the existing design return periods. The number of rivers that were upgraded from the existing return period were 65, which have relatively large flooding areas and have large PFDs. Whereas, the number of rivers that were downgraded were 169.

• The Journal of Engineering Geology
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• v.29 no.2
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• pp.99-112
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• 2019

Rainfall infiltration through the unsaturated zone is influenced by a range of factors including topography, geology, soil, rainfall intensity, temperature and vegetation; the actual infiltration varies largely in time and space. The infiltration capacity of soil is a critical factor in identifying groundwater recharge and leakage of surface water. It may differ depending on soil types and geological features of a particular basin or territory as well as on the usage of the land. This study was conducted in forest and farmland region of the mid-mountain area (EL. 50~300 m) of Jeju Island to test soil infiltration capacity of the area where rainfall contributes to groundwater. Results were analyzed using the four soil group classification methods presented by Jeong et al. (1995) and NAS (2007) to discover that the method offered by NAS (2007) is more reliable in the mid-mountain area of Jeju Island. The study compares and reviews the existing classification methods using the results of infiltration capacity tests executed on different soil groups throughout the whole region of the Jeju mid-mountain area. It is expected that this work will serve as a guideline for evaluating surface water recharge and hydraulic characteristics of Jeju Island.

• Korean Journal of Ecology and Environment
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• v.54 no.1
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• pp.1-11
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• 2021

Fish community characteristics was investigated in Namyang Lake and tributaries in Han River basin, Korea from April to October 2015. During the period, there were 5,672 individuals of 20 species appeared from tributaries (St. 1~St. 6) and dominant species were Pseudorasbora parva (33.5%). Also 5,672 individuals of 20 species appeared in Namyang Lake (St. 7~St. 9) and dominant species were Carassius auratus (32.2%). There were 5 species of endemic species with Rhodeus uyekii, Acanthorhodeus gracilis, Squalidus japonicus coreanus, Abbottina springeri and Odontobutis interrupta from Namyang Lake watershed. The frequency of endemic species were higher tributaries (18.5%) than Namyang Lake (15%). Exotic species were 3 species with Carassius cuvieri, Lepomis macrochirus, and Micropterus salmoides. there were appeared more frequently Namyang Lake (15.0%) than tributaries(7.4%).