• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.17-17
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• 2011

As a method of countermeasure to bed degradation and armoring phenomena of bed material in the downstream area of dam reservoirs, sediment augmentation (replenished sediment) has been carried out in many Japanese rivers. In general, bed of the replenished sediment site is composed of rocks, because the site is located in the downstream area of the dams and sediment supply is very small. Bed deformation process has been researched by many researchers. As a method of countermeasure to bed degradation and armoring phenomena of bed material in the downstream area of dam reservoirs, sediment augmentation (replenished sediment) has been carried out in many Japanese rivers. In general, bed of the replenished sediment site is composed of rocks, because the site is located in the downstream area of the dams and sediment supply is very small. Bed deformation process has been researched by many researchers. However, most of them can treat movable bed only and cannot be applied to the bed deformation process of sediment on rocks. If the friction angle between the sediment and the bed surface is assumed to be the same as the friction angle between the sediment and the sediment, sediment transport rate must be smaller without sediment deposition layer on the rocks. As a result, the reproduced bed geometry is affected very well. In this study, non-equilibrium transport process of non-cohesive sediment on rigid bed is introduced into the horizontal two dimensional bed deformation model and the model is applied to the erosion process of replenished sediment on rock in the Nakagawa, Japan. Here, the Japanese largest scale sediment augmentation has been performed in the Nakagawa. The results show that the amounts of the eroded sediment and the remained sediment reproduced by the developed numerical model are $56300m^3$ and $26800m^3$, respectively. On the other hand, the amounts of the eroded sediment and the remained sediment measured in the field after the floods are $56600m^3$ and $26500m^3$, respectively. The difference between the model and field data is very small. Furthermore, the bed geometry of the replenished sediment after the floods reproduced by the developed model has a good agreement with the measured bed geometry after the floods. These results indicate that the developed model is able to simulate the erosion process of replenished sediment on rocks very well. Furthermore, the erosion speed of the replenished sediment during the decreasing process of the water discharge is faster than that during the increasing process of the water discharge. The replenished sediment is eroded well, when the top of the replenished sediment is covered by the water. In general, water surface level is kept to be high during the decreasing process of the discharge during floods, because water surface level at the downstream end is high. Hence, it is considered that the high water surface level during the decreasing process of the water discharge affects on the fast erosion of the replenished sediment.

• Land and Housing Review
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• v.6 no.3
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• pp.147-152
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• 2015

Site coefficient and amplification factor of current domestic Seismic Design Code based on American Seismic Code, have no consideration for the domestic ground condition in which the base rock is normally placed within 30m form the surface. By previous studies, the measured spectral acceleration of the result of dynamic centrifugal test and analysis was smaller than the design spectral acceleration for the period over 1.5 sec. Accordingly, in this study structural analysis and design using dynamic centrifugal test result for pile foundation were achieved, and the quantity of concrete and reinforcement of wall frame was compared with each other. Comparison results of cost using KBC the design spectral acceleration of SC, SD site and SDS, the quantity of reinforcement using SDS for SD site was 17~23% smaller than using the design code SD site.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.5
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• pp.233-247
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• 2024

The damage to structures during an earthquake can be varied depending on the frequency characteristics of seismic waves and the geological properties of the ground. Therefore, considering such attributes in the design ground motions is crucial. The Korean seismic design standard (KDS 17 10 00) provides design response spectra for various ground classifications. If required for time-domain analysis, ground motion time series can be either selected and adjusted from motions recorded at rock sites in intraplate regions or artificially synthesized. Ground motion time series at soil sites should be obtained from site response analysis. However, in practice, selecting suitable ground motion records is challenging due to the overall lack of large earthquakes in intraplate regions, and artificially synthesized time series often leads to unrealistic responses of structures. As an alternative approach, this study provides a case study of generating ground motion time series based on the hybrid broadband ground motion simulation of selected scenario earthquakes at sites in the Nakdonggang delta region. This research is significant as it provides a novel method for generating ground motion time series that can be used in seismic design and response analysis. For large-magnitude earthquake scenarios close to the epicenter, the simulated response spectra surpassed the 1000-year design response spectra in some specific frequency ranges. Subsequently, the acceleration time series at each location were used as input motions to perform nonlinear 1D site response analysis through the PySeismoSoil Package to account for the site response characteristics at each location. The results of the study revealed a tendency to amplify ground motion in the mid to long-period range in most places within the study area. Additionally, significant amplification in the short-period range was observed in some locations characterized by a thin soil layer and relatively high shear wave velocity soil near the upper bedrock.

• Korean Journal of Heritage: History & Science
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• v.47 no.1
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• pp.82-101
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• 2014

The purpose of this study was to survey and analyze the origin story and the legends associated with Yongyudam(龍遊潭, Dragon Creek), its scenic and spatial description in Climbing Writings(遊山記: Yusangi Notes), its geographical and geological features, its surrounding remains and letters chiseled on the rocks through the field study and the study on literatures associated with it so to identify its significance and value and then to ensure justification on preservation of Yongyudam scenic site. Conclusions of this study are as follow. As the traditional scenic place 'Geumdae-Jiri(金臺智異)' representing Hamyang-gun(咸陽郡) depicts Mount Cheonwangbong and 'Yongyudong Village(龍遊洞)', ancient maps and literatures have positioned Yongyudam as the center of Eomcheon-river Creek as well as the representing scenic site of Yongyudong Village. Core images in the spatial awareness of Yongyudam described in our ancestors' Climbing Writings Notes on Jirisan Mount are 'geographical and scenic peculiarity associated with swimming dragons', 'potholes in various shapes and sizes scattered on rocks', 'loud sound generated by swirling from shoals' and 'the scenic metaphor from the dragon legend', which have led scenic features of Yongyudam scenic site. In addition, significant scenic metaphors from legends such as 'Nine Dragons and Ascetic Majeog' and 'Kasaya Fish' as well as 'the Holy Place of Dragon God', the rain calling magic god have descended not only as the very nature of Yongyudam scenic site but also the catalyst deepening its mystic and place nature. On the other hand, Jangguso Place(杖?所, Place of Scholars) in the vicinity of Yongyudam was the place of resting and amusement for scholars from Yeongnam Province, to name a few, Kim Il-son, Cho Sik, Jung Yeo-chang and Kang Dae-su, where they experienced and recognized Jirisan Mount as the scenic living place. Letters Carved on the rocks at Jangguso Place are memorial tributes and monumental signs. Around Yongyudam, there are 3 stairs, letters chiseled on the rocks and the water rock artificially built to collect clean water, which are traditional scenic remains detectable of territoriality as the ritual place. In addition, The letters on the rock at Yongyudong-mun(龍遊洞門) discovered for the first time by this study are the sign promoting Yongyudam as the place of splendid landscape. The laconism, 'It is the Greatest Water in Jirisan Mount(方丈第一山水)' on a rock expresses the pride of Yongyudam as the representing scenic place of Mount Jirisan. Other than those, standing rocks such as Simjindae Rock, Yeong-gwidae Rock and Ganghwadae Rock show the sign that they are used as amusement and gathering places for ancestor scholars, which add significance to Yongyudam. By this study, it was possible to verify that Yongyudam in Mount Jirisan is not simply 'the scenic place in the tangible reality' but also has seamlessly inherited as the traditional scenic attraction spiritualized by overlapped historical and cultural values. Yongyudam, as the combined heritage by itself, shows that it is the product of the place nature as well as unique ensemble of cultural scenic attraction inherited through long history based on natural scenery. It is certain that not only the place value but also geographical, geological, historical and cultural values of Yongyudam are the essence of traditional scenic attraction, which should not be disparaged or damaged by whatever political or economic interests and logics.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1C
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• pp.65-76
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• 2010

Recent earthquake events revealed that severe seismic damages were concentrated mostly at sites composed of soil sediments rather than firm rock. This indicates that the site effects inducing the amplification of earthquake ground motion are associated mainly with the spatial distribution and dynamic properties of the soils overlying bedrock. In this study, an integrated GIS-based information system for geotechnical data was constructed to establish a regional counterplan against ground motions at a representative metropolitan area, Seoul, in Korea. To implement the GIS-based geotechnical information system for the Seoul area, existing geotechnical investigation data were collected in and around the study area and additionally a walkover site survey was carried out to acquire surface geo-knowledge data. For practical application of the geotechnical information system used to estimate the site effects at the area of interest, seismic zoning maps of geotechnical earthquake engineering parameters, such as the depth to bedrock and the site period, were created and presented as regional synthetic strategy for earthquake-induced hazards prediction. In addition, seismic zonation of site classification was also performed to determine the site amplification coefficients for seismic design at any site and administrative sub-unit in the Seoul area. Based on the case study on seismic zonations for Seoul, it was verified that the GIS-based geotechnical information system was very useful for the regional prediction of seismic hazards and also the decision support for seismic hazard mitigation particularly at the metropolitan area.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.414-419
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• 2005

This study was performed to compare the treatment efficiencies of two media, newly developed Bio-rock and conventional gravel, in soil clothing contact oxidation process. The composition of synthetic wastewater were $COD_{Cr}$ $150{\sim}370\;mg/L$, $BOD_5$ $150{\sim}270\;mg/L$, T-N $20{\sim}60\;mg/L$, T-P $5{\sim}25\;mg/L$, pH 7 and 2 mL/L of trace element solution. The experiment using two reactors was comparatively conducted for the flow rate of 40 L/d for 13 months, respectively. Initially Bio-rock reactor was increased to pH 12 due to $Ca(OH)_2$ with hydration of cement, but gravel reactor was dropped to pH 4 due to the degradation of organic material and nitrification. This significant pH variation deteriorated the growth and activity of microorganism. But the high pH of Bio-rock seems favorite to ammonia stripping and precipitation of phosphate. Such pH variation of Bio-rock and gravel reactors were finally stabilized to pH 8 and pH 6, respectively. The removal efficiencies of organic compounds from Bio-rock reactor were 96% of $COD_{Cr}$, 98% of $BOD_5$, 80% of T-N and 85% of T-P which stably coping against variation of influent concentration. But those of gravel reactor were 96% of $COD_{Cr}$, 96% of $BOD_5$, 42% of T-N and 40% of T-P, respectively. The Bio-rock was 2 times higher than T-N and T-P in treatment efficiency. And electron-microscopic examination showed that Bio-rock was more favorable to microbial adherence than gravel. The microbial populations were $5.2{\times}10^6\;CFU/mL$ of Bio-rock reactor compared to $2.6{\times}10^6\;CFU/mL$ in gravel reactor. In result Bio-rock was favor to microbial adherence and high treatment efficiency in spite of variation of influent concentration which had the advantages in saving running time and reducing site requirement.

• The Journal of the Petrological Society of Korea
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• v.17 no.4
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• pp.191-205
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• 2008

In order to use the geologic information data such as industrialization of rock resources, site enlargement and development planning, distributive ratios of rock types and geologic ages were obtained by the ArcGIS 9.2 program, and digital geologic and geographic maps of 1:250,000 scale, in the Chungbug, Chungnam and Daejeon areas, respectively. In the Chungbug area, 64 rock kinds are developed and their geologic ages can be classified into 8 large groups. In the geologic ages, the ratios are decreasing in the order of Jurassic, Precambrian, Age-unknown, Cretaceous, Quaternary, Cambro-Ordovician and Carboniferous-Triassic ages, all of which comprise most ratios of 98.48% in the area. In the rock types, the ratios show the decreasing order of Jurassic Daebo granite, Precambrian banded gneiss of Gyeonggi metamorphic complex, Cretaceous biotite granite, Quaternary alluvium, Great limestone group, Lower phyllite zone and Meta-sandy rock zone of age-unknown Ogcheon group, Triassic Cheongsan granite, Precambrian granitic gneiss of Gyeonggi gneiss complex, Pebble bearing phyllite zone of age-unknown Ogcheon group and biotite gneiss of Sobaegsan metamorphic complex, all of which comprise the prevailing ratio of 84.27% in the area. In the Chungnam area, 35 rock types are developed and their geologic ages can be classified into 6 large groups. In the geologic ages, the ratios are decreasing in the order of Precambrian, Jurassic and Quaternary ages, which occupy the prevailing ratio of 87.55% in the area. In the rock types, the ratios show the decreasing order of Jurassic Daebo granite, Precambrian banded gneiss of Gyeonggi metamorphic complex, Quaternary alluvium, Precambrian granite and granitic gneiss of Gyeonggi gneiss complex, Cretaceous acidic dykes, Lower phyllite zone and Pebble bearing phyllite zone of age-unknown Ogcheon group and Quaternary reclaimed land, which occupy the ratios of 74.28% in the area. In the Daejeon area, 11 rock types are developed and their geologic ages can be classified into 5 large groups. In the ages, the ratios are decreasing in the order of Jurassic, Age-unknown and Quaternary, which occupy most ratios of 93.40% in the area. In the rock types, the ratios show the decreasing order of Jurassic Daebo granite, Quaternary alluvium and Lower phyllite zone and Pebble bearing phyllite zone of age-unknown Ogcheon group, which occupy the prevailing ratios of 91.09% in the area.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.36 no.2
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• pp.11-20
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• 2018

This study is to review about Yeongpyeong(永平), Baengnoju(白鷺洲)'s status and meaning landscape from literature and carved letter by literature reviews and a field survey. Baengnoju is named from mounting Geumneung(金陵) Bonghwangdae(鳳凰臺) poetry written by I, Baek(李白). There were many 'Baengnojus' all over the country but Yeongpyeong Baengnoju was the most famous beauty spot in Joseon dynasty. We identified many documentations about carved letter in the rock by literature reviews. So We guessed Baengnoju's past landscape and discovered undiscovered carved letters in the rock. Baengnoju became a famous place by Yang, Man-go(楊萬古)'s villa and I, Myeong-Han(李明漢)'s poetry. After this, it had received attention because it had a fine view and a good place to live. We thought that Baengnoju's documentations about carved letter in the rock was the most important, because carved letter in the rock is the fundamental factor to explore a noted wiseman' trace. Especially, documentations about carved letter in the rock was concentrated with Seoin(西人)'s literature. It is the important materials to identify carved letter in the rock. We studied about Baengnoju's carved letter in the rock by literature reviews and a field survey. First of all, it was identified as Jo, Sang-Wu(趙相愚) who wrote "Baengnoju" letter. We also discovered two undiscovered letters in Baengnoju letter's left side. There were Yu, Gi-Il(柳基一)'s carved letter in the rock in the other side. It was many carved letters in the rock in Baengnoju, but we knew so many differences comparing with literature. So, we need to establish plans to preserve. On this occasion, we wish that many people will be pay more attention to Baengnoju.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.2
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• pp.193-205
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• 2008

The construction of underground structures such as oil and food storage caverns are recently increasing in our country. The stability of those underground caverns are greatly influenced by their shape and size. In this study therefore, the effect that the shape of an underground cavern have on its stability were analyzed in terms of safety factor. To this end, caverns with 5 different shapes were investigated and sensitivity analyses were performed based on rock class, overburden, and lateral earth pressure coefficient. The proper amount of shotcrete and rockbolt as supports of a cavern was also assumed based on the shape and site of the cavern and rock conditions. This study is expected to be helpful in designing and evaluating the stability of caverns in future.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.1
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• pp.100-111
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• 2006

This study was carried out to increase the efficiency of site investigation through the evaluation of the applicable methods of investigation for cutting slope design. In an effort to find out the applicability of the method employed during the slope investigation, some tests were carried out on 6 subjects i.e location of weak zones, characteristics of discontinuities, distribution of strata, in situ tests for geo-technical properties, laboratory test and estimation of weathering. The method was highly applicable and produced expected results during the test of weak zones, discontinuities and distribution of strata. In order to apply the method to in- situ test for geo-technical properties and laboratory test on soil and rock slope, a statistic analysis of the existing data were required in advance. However its design applicability on rock slope was good although actual cases of application were not many due to limitation of the cases for investigation. The method was frequently referenced but not actually applied for anti seismic design test and estimation of weathering.