• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.33-43
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• 2002

Recently, as large constructions on the coast increase, an application of a surface layer stabilization method which is one of the improvement methods for dredged soft clay has increased. However, there are few studies about this. The purpose of this study is clarifying characteristics of ultra-soft marine clay and hardening agent. Also, it is verifying an optimal mixture ratio of hardening agent through the laboratory tests according to designed experiments and proving by statistical analysis and pilot tests. Laboratory tests were performed with proper hardening agent and test soil in accordance with the design of experiments. Regression equations between hardening agents materials and unconfined compressive strength were derived from the tests. The applicability of regression equations were also verified by pilot tests. From the test results, it was found that hardening agent materials(cement, slag, fly-ash, inorganic salts, arwin, gypsum etc.) have some effect upon compressive strength. The optimal mixture ratio which satisfies the required compressive strength was derived from the statistical analysis. The effect of ground improvement by cements and hardening agents was confirmed through the pilot tests. This study will suggest data for design or construction criteria of stabilization of surface layer on ultra-soft marine clay.

• The Journal of Engineering Geology
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• v.22 no.1
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• pp.39-48
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• 2012

The behaviors of a diaphragm wall and a contiguous pile wall such as CIP(Case-in-place pile) and SCW(Soil-cement wall), applied to the top-down construction method, were analyzed using the SUNEX program, which is widely used to design earth retaining walls. Four types of earth pressures, as described by Rankine (1857), Terzaghi and Peck (1967), Tchbotarioff (1973), and Hong and Yun (1995a), were applied to the analysis program to predict the lateral displacement of walls. The results show that the displacements of an earth retaining walls vary with the applied earth pressure. The predicted lateral displacement based on Hong & Yun's (1995a) earth pressure is similar to the measured displacement. Therefore, the actual lateral displacement of an earth retaining wall, as applied to top-down construction method, can be accurately predicted by using an analysis program considering Hong and Yun's (1995a) earth pressure.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.743-748
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• 2010

The stability forecasting of rock slope is more difficult than soil slope because catching the sign of failure in monitoring is not easy and deformation of the rock is small in failure process. But in the rock slope, there is small deformation like crack propagation in rock itself and it accumulates gradually in failure process. If it is possible to detect the small change in the rock slope, we can know the failure time exactly. Because the individual signal is gathered in the acoustic emission monitoring, it is possible to monitoring the slope if many sound signal is accumulated. Detection test of acoustic emission was performed. Uniaxial, two types of bending test, and two plane shear test were done with various cement paste sample. Wave propagation velocity of uniaxial test sample was increased with curing time. Wave Analysis give us the result that there is a AE sign signal before the failure, the AE count is suddenly increased. And frequency level 125kHz before failure is changed to level 200-250kHz after failure. In two plane shear test we can catch the AE signal and can know the failure type from wave shape. Monitoring test site is tunnel slope in Hongcheon but special signal is not collected.

• Journal of the Korean Institute of Rural Architecture
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• v.20 no.2
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• pp.49-56
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• 2018

The vernacular houses with 田-shaped floor plan at Gangreung have been played important roles in tracing the vernacular living cultures including housing life. But due to the adoption of convenient facilities in vernacular housing lives caused by modernization and urbanization, many changes and transformations have happened at residential space of vernacular houses. This thesis targets to extract basic data to prepare and prevent various problems in process of renovation, extension and function change as installing housing life facilities, and to identify the changes and transformations of them to prepare the proper balances between their original form preservation and residents' convenience living. The results are as follows. The inner wall removal of rooms, the fuel change of cooking and heating, the leveling change of kitchen floor made possible the sedentary lifestyles. And its residential rooms were transformed from two row to one row by inner wall removal, the fuel heating change, the heating method change and the heat insulating materials. The residential extension materials were changed from the traditional materials such as soil, wood, etc to the modern materials such as cement block or brick, sandwich panel, etc. And the modern materials were used and attached to widen residential spaces to the vernacular house because of the easiness of execution. So, it is necessary for 田-shaped floor plan vernacular house owners to distribute printed execution guide book to prevent and minimize the various problems to be shown by extension, renovation and function change.

• Journal of the Korean Geotechnical Society
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• v.16 no.4
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• pp.43-50
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• 2000

This paper presents the measured performance of in-situ walls using the measured data collected from various deep excavation sites in urban area. A variety of in-situ wall systems from 57 sites were considered, including H-pile walls, soil cement walls, cast-in-place pile walls, and diaphram walls. The examination included lateral wall movements as well as apparent earth pressure distributions. The measured data were thoroughly analyzed to investigate the effects of various components of in-situ wall system, such as types of wall and supporting system, on the lateral wall movement as well as on the apparent earth pressure distribution. The results wee then compared with the current design/analysis methods, and information is presented in chart formes to provide tools that can be used for design and analysis. Using the measured data, a semi-empirical equation for predicting deep excavation induced maximum lateral wall movement is suggested.

• Journal of the Korean Geotechnical Society
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• v.19 no.1
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• pp.51-60
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• 2003

As piling works in urban area are increasing, SIP which has low noise & vibration piling method takes the place of driven pile which has good bearing charateristics and is economical. Although SIP has been used far more than 15 years and it's use is increasing year by year, accurate analysis of bearing mechanism of SIP is not enough. So the design of SIP is much more conservative than driven pile. This paper is aimed at analysing the bearing charateristics of 103 SIPs constructed in Korea to give rational design criteria. Research result shows that bearing capacity of SIP is 40% lower than that of driven pile and conservative Meyerhof(20$\bar{N}_b'A_b$) method produced closer result to load test results than any other design method. And this result shows that in order to use optimised design criteria for the economical SIP design, quality control criteria must be settled down to produce high bearing capacity.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.483-490
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• 2005

At present around 50 companies have their own crushing plants, which manufacture rock into crushed sand, over around 350 different quarry throughout the nation. However, in most plants the stone dust sludge is left as it is in their plants so that they have difficulty to utilize. Furthermore, environmental pollution may be even caused due to dust generated when it is dried. Recycling is starting capturing the attention of the people working over the quarry due to the reasons described above. This research has studied in the quarters the usability as landfill liner of the stone dust sludge, which is industrial waste. We investigated what technological properties it would have after mixing the stone dust sludge with SM(sandy soil) first and then with blast furnace slag or reject ash, which is waste, and cement as the stabilizer. As the result of three tests; compacting test, strength test, and permeability test; to satisfy the regulatory guideline of the government that is the compress strength over 5 $kgf/cm^2$, the flexibility over 1 $kgf/cm^2$, and the permeability under $1.0{\times}10^{-7}cm/sec$ From this research, we could confirm that stone dust sludge would be used as waste landfill liner if it were mixed with other waste by the proper mixing ratio.

• Journal of Korean Society for Atmospheric Environment
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• v.11 no.2
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• pp.179-184
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• 1995

This study was carried out to characterize sources of suspended particulate matter(SPM) in Mt. Soback area from January to Novembver in 1993. The collection and major water soluble ion analysis of SPM were conducted by using a High Volumn Air Sampler(HVAS; W&A Inc., PM-10) and ion chromatograph(DIONEX 4000i), respectively. The variations of SPM and major ion concentrations were found to be 9. sim. 156.mu.g/ $m^{3}$, $F^{-10}$ 0.00 .sim. 0.15.mu.g/ $m^{3}$, C $l^{-10}$ 0.06 .sim. 3.79.mu.g/ $m^{3}$, N $O_{3}$$^{-10}$ 0.90 .sim. 6.85.mu.g/ $m^{3}$, S $O_{4}$$^{2-}$ 1.99 .sim. 9.36.mu.g/ $m^{3}$ N $a^{+}$0.00 .sim. 0.27.mu.g/ $m^{3}$, N $H_{4}$ $^{+}$0.72 .sim. 5.77.mu.g/ $m^{3}$, $k^{+}$0.03 .sim. 0.88.mu.g/ $m^{3}$ and $Ca^{2+}$0.12 .sim. 2.76.mu.g/ $m^{3}$. Tree sources were identified by Principal Component Amalysis(PCA) using a SPSS/P $C^{+}$. The explanation ability of forst, second and third Principal Component were 60.8%, 13.6%, 8.2%, of total variance. The sources classfied by PCA were found to be secondary aerosol/fuel combustion, soil dust related cement production/yellow sand and aerosol related waste burning.related waste burning.g.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.2
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• pp.89-97
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• 2003

Experimental model studies were carried out to evaluate the end condition for drilled shafts by applying elastic impact on the top of the shaft, which is one of the various methods using stress waves. Typical impact responses corresponding to the various end conditions including free, fixed, rock-socketed, and soft-bottom with good and poor side contact conditions, were investigated. In order to simulate these renditions, mock-up shaft models made of cement mortar were used. Small-scale laboratory experiments were also performed, and field tests were carried out for the shafts that were socketed into weathered rock. It is found that the rock-socketed condition and depth of penetration into rock ran be identified from the reflection at the interface between the soil and rock in the waveform. The soft bottom rendition can be identified, only when the side contact between shaft and surrounding rock is poor, whereas it cannot be identified when the side contact is good because the waveform is similar to that of fixed end rendition.

• Journal of Korean Society of Rural Planning
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• v.19 no.1
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• pp.23-32
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• 2013

In the traditional subsistence farming era in Korea, most of small farmer's housing plots in the rural villages had their boundary barriers of which materials being the natural ones provided from nearby places. However, during the rapid industrialization period from 1960s, a traditional type of boundary barriers in the rural villages had been replaced mostly by low-cost factory-made ones, which means absolute loss of their amenity values as a linear part of villagescape. In spite of many study efforts on boundary barriers of traditional rural houses, detailed historical dating on them after 1960s have not tried up to now, which provoked to try this study. Through the direct and in-depth interviews to rural villagers sampled from 21 case villages, it was found that original boundary barriers structure in most of farm houses was made of natural materials like stone, soil, trees and bamboo, but, replaced by cement block structures mostly during Saemaeul Project period. However, although being relatively minority, traditional ones have been preserved up to now mainly in remote mountainous and seashore villages, but was in very low condition. In the overall view, for more than half a century, boundary barriers of farm houses had been left without public or private improvement efforts. In order to enhance their amenity values, more research works should be carried out on positive reassessment of the traditional ones harmonized with multifunctionalities for modern village life.