• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.638-645
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• 2010

This study introduces a reinforcement work case using Twin-Jet Method. The area is located behind the abutment of the bridges built on soft clay along the $\bigcirc\bigcirc$ Express Highway. Its foundation was constructed by installing EPS blocks on the original ground to reduce the embankment load under the highway. However, the ground deformation has continuously occurred due to the settlement of the foundation soft cohesive soils. The amounts of subsidences at the surface turned out to be 20~30.0mm, After the pavement patch work on April 23, 2009, a drastic subsidence occurred together with 10mm swell, For this reason, Twin-Jet grout column construction was applied by passing through the EPS banking blocks without closing traffic flows on the express highway. The outcomes of core sample tests after reinforcing the ground turned out to be TCR 92.5%, RQD 64.6% and unconfined compressive strength 2.3~8.6Mpa. The test results showed that the condition of the ground foundation had improved using Twin-Jet grouting in most layers of ground including the cobble and gravel layer.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.3
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• pp.90-96
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• 2007

Modern waste management units, so-called "landfills" protect human health and environment from hazardous leachate and gas. Accordingly, it must be constructed with a bottom liner system that includes a gas collection layer. Leachate is the contaminated liquid that drains from the waste material pollutes ground water. For this reason. bottom liner system must have durability and low hydraulic conductivity (in case of compacted clay liner, no more than $1{\times}10^{-7}cm/sec$ ). P county in Kangwon province constructed a solid waste landfill with bottom liner system. In this study. it is mainly introduced that the test results on construction and quality control of bottom liner system by "Multiple composite liner construction technology", which is selected for bottom liner system in P solid waste landfill.

• The Journal of Engineering Geology
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• v.27 no.3
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• pp.305-312
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• 2017

The most effective way to distinguish subsurface interfaces that produce various geophysical responses is through the integration of multiple geophysical methods, with each method detecting both a complementary and unique set of distinct physical properties relating to the subsurface. In this study, shallow seismic reflection (SSR) and ground penetrating radar (GPR) surveys were conducted at the Cheongju-Gadeok site of the Korea National Groundwater Monitoring Network to map the water table, which was measured at 12 m depth during the geophysical surveys. The water table proved to be a good target reflector in both datasets, as the abrupt transition from the overlying unsaturated weathered rock to the underlying saturated weathered rock yielded large acoustic impedance and dielectric constant contrasts. The two datasets were depth converted and integrated into a single section, with the SSR and GPR surveys conducted to ensure subsurface imaging at approximately the same wavelength. The GPR data provided detailed information on the upper ~15 m of the section, whereas the SSR data imaged structures at depths of 10-45 m. The integrated section thus captured the full depth coverage of the sandy clay, water table, weathered rock, soft rock, and hard rock structures, which correlated well with local drillcore and water table observations. Incorporation of these two geophysical datasets yielded a synthetic section that resembled a simplified aquifer model, with the best-fitting seismic velocity, dielectric constant, and porosity of the saturated weathered layer being $v_{seismic}=1000m/s$, ${\varepsilon}_r=16$, and ${\phi}=0.32$, respectively.

• The Journal of Engineering Geology
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• v.27 no.4
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• pp.417-427
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• 2017

This study aims to present cases of rock slope failures caused by geological structures. Status of slope failures, results of cause analysis and stabilizing methods are introduced, focusing primarily on rock slope failures caused by specific geologic structures, such as intersection of faults infilled with clay, foliation and fault shear zone by dike intrusion and deep-seated clayey layer along lithologic boundary. Detailed geological survey, geophysical exploration and boring survey were conducted for cause analysis. Stabilizing method to prevent further slope failures and to ensure long-term stability of slopes were established, considering characteristics of geological structures, types of failure and geological conditions.

• Magazine of the Korean Society of Agricultural Engineers
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• v.32 no.1
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• pp.72-86
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• 1990

This study was carried out to get the basic information of irrigation plans for upland crops such as the optimum irrigation level and the project water requirement. Red peppers and cucumbers were cultivated in PVC pot lysimeters filled with 60cm deep clay loam soil. Four tensiometers were installed in each pot to measure the soil water pressure head. Six levels of irrigation were used. The results obtained from this study are summarized as follows: 1.The optimum irrigation level. The irrigation level of FC-PF2.7 was found to be the optimum level for both red pepper and cucumber with respect to the yield and the weight per fruit. In case of FC-PF2.7, total ET during the irrigation period were 1005.2mm for red pepper, and 429.6mm for cucumber, respectively. 2.soil moisture extraction patterns. Average soil moisture extraction patterns (SMEP)during the irrigation period were from 1st soil layer 43% : 32% : 16% : 9% for red pepper and 39% : 34% : 15% : 12% for cucumber, respectively. The extraction ratio of the upper soils showed very large values during the early stage of growth and decreased largely during the middle stage, and became larger in the last stage. 3.The project water requirement. Among the reference crop evapotranspiration(ETo) computation methods presented by FAO, the Penman method was found to be the best. The effective rainfall was computed by a modified USDA-SCS curve number equation. Availability ratios of the total rainfall during irrigation season were 59.2% for red pepper and 48.9% for cucumber, respectively. Net project water requirement of design year are 837.3mm for red pepper. and 502.Smm for cucumber, respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.6
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• pp.256-260
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• 2014

This study was carried on the phenomena in reactivity with the clay surface according to the thickness of the cobalt component coating. In the coated specimen, it was observed that the cobalt component was spreaded to diffuse with a constant thickness from the surface of it and the diffusion layer at the white porcelain soil was more increased with the increase of the amount of cobalt sulfate than at the celadon porcelain one. It was evaluated that the color of the surface on the coated specimen at the white porcelain soil was changed from grayish blue to blue and the $L^*$ value was decreased from 51.78 to 37.61 and also in the case of the coated specimen in celadon porcelain soil, $L^*$ value was from 53.91 to 38.93 and the color was from dark olive gray to dark gray. The physical properties of the specimen were characterized by X-ray diffraction, Scanning electron microscope, Dilatometer, TG-DTA, UV-vis spectrophotometer and HRDPM.

• Journal of the Korean GEO-environmental Society
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• v.10 no.2
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• pp.29-36
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• 2009

A series of two-dimensional (2D) finite element analyses have been performed to study the behaviour of single piles in consolidating ground. The analysis was conducted based on coupled analyses by considering changes of pore water pressure in the clay. In the analyses the soil slippage at the pile and the soil interface has been included. The method widely used in practice somewhat overestimates dragload by about 25% compared to the rigorous numerical analysis since partial mobilization of skin friction near neutral plane and reductions in the vertical soil stress is not incorporated. When soil slip develops at most of the pile length at the pile-soil interface during consolidation, further increases in dragload is not significant. Application of coating on the pile surface can reduce dragload and pile settlement substantially, but under an axial load on the pile head very large pile settlement can be developed unless pile tip is located to a stiff bearing layer.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.107-112
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• 2005

Road is built continuously along with development of industry and cut slope is happened necessarily in road construction. Geoengineers are executing cut slope stability analysis considering various cut slope condition such as topography, geology, hydraulic condition and so on. The Tertiary Jungja Basin is located in the southeastern coastal area of the Korea Peninsula. Jungja Basin area is created by geotectonic movement of the plate after Early Miocene epoch. The northwestern and southwestern boundary of the basin is fault zone. The Basement rock is hornfels (Ulsan Formation). Basin-fills consist of extrusive volcanic rock(Tangsa Andesites), unconsolidated fluviatile conglomerate(Kangdong Formation) and shallow brackish-water sandstone(Sinhyun Formation). The characteristics of cut slopes in this area is different with cut slopes in the other site. Soil layers in this area is unconsolidated sediments and is not formed the weathering and erosion of the rock. So, the depth of soil layer is very thick. Faults of this area are northwest-southeast and northeast-southwest direction. Expandible clay mineral as smectite, chlorite et al. detected from fault gouge using XRD. Therefore, Jungja Basin area must consider the characteristics of the faults and soil layers thickness necessarily cut slopes stability analysis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.3
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• pp.160-166
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• 2007

The coarse deposit with a lower mud content adjacent to the shelf of the southern East Sea is probably a "relict" sediment deposited in response to a lower stand of sea level during the Pleistocene. The sediment that developed on the slope and in the deep sea was river-borne primarily and was secondarily reworked or redistributed by the Tsushima Warm Current from the East China Sea. The clay mineralogy of the area suggests various sources of fine-grained sediment from adjacent rivers, the Korea Strait, volcanic material from Ulleung Island, and the Japan coast. Massive sand, bioturbated mud, homogeneous mud, and laminated mud were the dominant facies found in the core sediments from the study area. The massive sand was mainly volcanic ash from an eruption on Ulleung Island (9300 yr BP) and consisted of colorless pumiceous glass and a black scoriaceous type. The sedimentation rates on the slope, based on the Ulleung-Oki ash layer, were about 10cm/ky higher than in the basin. Other than the coarse-grain sediment, the mean size of the fine sediment dominating the bioturbated and homogeneous muds in the basin and the laminated mud on the slope was 6-10 phi. This indicates a difference in the major sedimentary process: hemipelagic sedimentation in the Ulleung Basin and mass flow deposition, such as turbidite, on the slope of the southern East Sea.

• Conservation Science in Museum
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• v.16
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• pp.32-45
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• 2015

The bronze incense burner, discovered in Chungung-dong, Hanam, Gyeonggi-do in 1971, is a hanging incense burner dating from the Goryeo period. The incense burner was covered with a thick layer of clay. The object was in a severely deteriorated state, affected by bronze disease which resulted in extensive corrosion. Numerous cracks were present across its surface, and some parts had been broken off. To preserve and display the bronze incense burner in a stable condition, deposits of foreign material were removed from the surface, and the weakened metal was strengthened. Cracked and broken areas were reinforced using woven glass fiber, followed by the application of epoxy resin to restore the shape. To investigate the method of production, a chemical analysis was performed, and the microstructure was examined. The chemical analysis revealed that the body of the incense burner as well as the ear, loop, lid and the knob were cast in a ternary alloy of Cu-Sn-Pb. Moreover, copper nails with high copper content were used to securely join the ear to the body of the incense burner. The microstructure was mainly α-phase, and non-intermetallic inclusions composed of Cu and S were detected.