• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.539-550
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• 2006

New Songdo city is currently developing on the reclaimed land on a marine deposit and among the development the four sixty-four(64) stories high rise buildings are under construction at block 125. The ground condition of the site is comprised of a deep seated weathered rock staratum under a soft marine deposit layer. As a foundation system, a bored pile was planned to transmit the applied load to the stable layer. In this study, the behavior of the weathered rock especially locating at a upper part having a weak strength(HWR, MWR) has been evaluated through series of hi-directional pile load test(BD PLT) carried out on the 3 drilled shafts socketed in a weathered rock layer in a design stage. It has been planned to increase the effect of the tests that the length of test piles was prepared short enough to perform the test under a high stress. The summary of the design reflecting the test results has been made up. In addition, the 4 hi-directional pile tests excuted on the working piles during the construction stage for the purpose of confirmation and the evaluation of the adequacy of the pile behaviors have been included in this study.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.1
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• pp.31-40
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• 2011

Purpose: This study was performed to investigate the actual state about ultrasonic cleaning of soft contact lenses in local optical shops and evaluate the removal effect of protein deposit on soft contact lenses with different lens containers by ultrasonic cleaner for eyeglasses. Methods: The actual state about ultrasonic cleaning of soft contact lenses was surveyed in total 75 local optical shops in Seoul, Korea. The cleaning efficacy of different lens containers was compared by measuring the protein remained on ocufilcon D contact lenses after washing by an ultrasonic cleaner for eyeglasses. The changes on surfaces and wetting angles of ocufilcon D contact lenses by repeat ultrasonication were further investigated. Results: The main purpose to use ultrasonic cleaners in local optical shops was rapid cleaning. The ultrasonic cleaning efficacy of ocufilcon D contact lenses with glass containers was little higher than it with plastic containers, but was not significantly different. The changes on surfaces and wetting angles of ocufilcon D contact lenses in a plastic lens container by repeat ultrasonication such as 30 and/or 60 times were shown. Conclusions: There was not significant difference in cleaning efficacy between glass and plastic lens containers. However, repeat cleaning with ultrasonic cleaner for eyeglasses would be carefully considered since some significant changes in the parameters of lens surface and wetting angles were detected by repeat ultrasonification even when lens containers were used for ocufilcon D contact lens during ultrasonictions.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.3
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• pp.227-234
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• 2010

Purpose: The cleaning effect of protein deposit and the change of contact lens parameters by ultrasonic cleaner for eye glasses on the soft contact lenses were investigated. Methods: Etafilcon A contact lenses contaminated with protein, was ultrasonicated by ultrasonic cleaner for eye glasses and for the control group, spoiled contact lenses were cleaned by multi-purpose solution. The remaining protein deposits on the contact lenses were determined after extraction and the changes of overall diameter, base curve, center thickness power, and water contents on contact lenses were measured and surfaces of contact lenses were observed by scanning electron microscope. Results: The cleaning efficacies of multi-purpose solution on protein deposited etafilcon A contact lenses were 6.08%, and 23.73~33.92% in the group of ultrasonic cleaner for eye glasses with multi-purpose solution and 0~12.99% in the group of ultrasonic clear for contact lens with multipurpose solution depending on the treatment time. The changes of parameters and surface on contact lenses by ultrasonication were not observed. Conclusions: Ultrasonic cleaner for eye glasses can be used to eliminate protein deposits for the diagnostic soft contact lens in the office since it was effective to eliminate protein deposits and not caused change of parameters on soft contact lenses.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.1
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• pp.113-122
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• 1999

The importance of the vertical response of a structure was well recognized after the Hyogoken-Nanbu earthquake of Japan. However, most of the seismic design codes does not specified the site sail profiles, and the sail and foundations conditions were mostly neglected in the vertical seismic analyses of a structure. In this paper, the effects of foundation size, sail layer depth under the foundation, foundation embedment and pile foundation on the vertical seismic response spectra for both surface and embedded mat foundation were studied to investigate the effects of the soft soil layer on the vertical response of a structure excited with the vertical components of Taft and El Centro earthquakes, considering the sail profile types of $S_A,S_C,S_E$ in UBC-97, the medium and large size foundations, the soil layer depth under the foundation of 30 and 60m, the foundation embedment of 0 and 15m, and the precast reinforced concrete bearing piles installed in the soft soil deposit. According to the study results, the foundation size has a little effect on the vertical seismic response, However, the soil layer depth under the foundation of 60m has to be considered for the vertical seismic analysis of a structure as for the horizontal one. The embedded pile foundations as well as the surface ones built on the soft soil layer amplified the vertical seismic response of a structure very much.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.3
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• pp.216-222
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• 2010

The structural methods used to protect coastal erosion are usually very expensive in construction as well as in spending on maintaining the structures from damage. Those structures like embankments, breakwaters, jetties etc. are commonly constructed with concretes (rigid methods) to protect coastal erosion. But those rigid methods are not effective always, because the wave energy and impact force on the structures could not be effectively reduced by those methods. For avoiding sediment erosion on coastal areas by the way of reducing wave energy, a flexible breakwater is introduced which will reduce energy and protect coastline economically and environmentally. The flexible device is a combination of flexible wire nets and stack of rings made of used vehicle tires and soft blades on surfaces. This flexible wire net is placed in between two stacks of rings. The stack of rings is mainly used to hold the flexible wire nets and the flexible wire net is mainly used to reduce wave energy and helps to deposit sediments in coastal area. For a field experiment study, the above-mentioned flexible breakwater of coastal protection has been set up at the Shuang-Chun coastal area in Tainan County since June 10, 2009. The length of the flexible device is 50.0 meters and the height is 2.0 meters. The function of the device has been examined by Typhoon Linfa during June 19~22, 2009 and by Typhoon Morakot during August 6~10, 2009. The result shows that the flexible breakwater has effectively trapped sediments and let them deposit on coastal. The depth of sediment deposition around the device was about 0.5 to 0.8 meters.

• Journal of the Korean Geotechnical Society
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• v.26 no.11
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• pp.17-28
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• 2010

Vertical drains are commonly used to accelerate the consolidation process of soft soils, such as dredged materials, because they additionally provide a radial drainage path in a deep soil deposit. In practice, vertical drains are commonly installed in the process of self-weight consolidation of a dredged soil deposit. The absence of an appropriate analysis tool for this situation makes it substantially difficult to estimate self-weight consolidation behavior considering both vertical and radial drainage. In this paper, a new method has been proposed to take into account both vertical and radial drainage conditions during nonlinear finite strain self-weight consolidation of dredged soil deposits. For 1-D nonlinear finite strain consolidation in the vertical direction, the Morris (2002) theory and the PSDDF analysis are adopted, respectively. On the other hand, to consider the radial drainage, Barron's vertical drain theory (1948) is used. The overall average degree of self-weight consolidation of the dredged soil is estimated using the Carillo formula (1942), in which both vertical and radial drainage are assembled together. A series of large-scale self-weight consolidation experiments being equipped with a vertical drain have been carried out to verify the analysis method proposed in this paper. The results of the new analysis method were generally in agreement with those of the experiments.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.2
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• pp.179-188
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• 2014

Purpose: The present study was aimed to investigate the cleaning efficacy of multi-purpose solutions containing different types and content of surfactants and their effect on the visible light transmittance of soft lens. Methods: Soft lenses made of different materials (etafilcon A and hilafilcon B) were deposited tear proteins by using the artificial tear and then compared the resulting cleaning efficacy and visible light transmittance after cleaning the lens with 6 types of multi-purpose solutions containing different content of surfactants. Results: The cleaning efficacy of multi-purpose solutions was variously shown as approximately 23~43% according to the active concentration of surfactants and surface tension in multi-purpose solution when etafilcon A lens cleaned with rubbing. The highest cleaning efficacy was detected when cleaned with the multi-purpose solution containing hydrogen peroxide besides surfactant however, the amount of remaining protein was still high on the lens. After washed with multi-purpose solution, the visible light transmittance of lens was in 89.8 to 90.8%. The amount of protein deposited on hilafilcon B lens was very small compared with it on etafilcon A lens even though it was incubated in artificial tears for 7 days, which showed 5~10% of protein amount in etafilcon A lens and the decrease of visible light transmittance was also not significant. In case of rubbing with multi-purpose solution, the cleaning efficacy on hilafilcon B lens was in 45.4 to 67.4% however, the order of cleaning efficacy of multi-purpose solution was different from it on etafilcon A lens. The visible light transmittance of hilafilcon B lens has been restored to the level of new lens. Conclusions: From the result, it is concluded that the appropriate multi-purpose solution should be selected according to the lens material and the amount of protein deposit on the basis of understanding surfactants and active principle for proper care of protein deposit on soft lens and the cleaning with rubbing is more efficient for lens care regardless of manufacturer's guideline.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.495-508
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• 2010

Vertical drains are commonly used to accelerate the consolidation process of soft soils, such as dredged materials. The installation of vertical drain provides a radial drainage path to water in the deposit soil in addition to the vertical direction. An estimation of time rate of settlement is considerably complicated when vertical drains are installed to enhance consolidation process of dredged material because the vertical drains are commonly installed before self-weight consolidation is ceased. In this paper, the vertical drain theory developed by Barron(1948) is applied to analyze the non-linear consolidation behavior considering radial drainage. The overall average degree of self-weight consolidation of the dredged soil under the condition that the water is drained in both radial and vertical directions is estimated using the Carillo(1942) formula. In addition, the Morris(2002) theory and the one-dimensional non-linear finite strain numerical model, PSDDF, are applied to analyze the self-weight consolidation in case of only the vertical drainage is considered. The new analysis approach proposed herein can simulate properly the time rate of the self-weight consolidation of dredged materials that is facilitated with vertical drains.

• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.281-290
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• 1999

The coastal area, particularly along the West and South coasts in Korea, is often reclaimed with dredged marine-clay to meet the demand of land capacity. A large number of ground improvement techniques are developed for such a newly formed soft clay deposit. However, the quick lime column method, which is effectively used for the purpose of ground improvement in the other countries, is seldom applied in Korea. This study, therefore, focuses on the development of appropriate soft soil improvement technique by using quick lime column. A model test as well as finite element analysis was conducted to identify the consolidation characteristics around the lime column. Although actual pore water pressure measured from model tests does not coincide with the predictions made by finite element method and Chen ＆ Law's theoretical formula, their trends are quite similar. It is revealed from this study that the pressure caused by the expansion of lime column affects considerably the consolidation characteristics of the surrounding ground.

• Journal of the Korean Geotechnical Society
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• v.27 no.1
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• pp.53-63
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• 2011

In this study, a composite behavior of stone columns reinforced in a soft ground, Sabkha, has been evaluated by performing a series of field measurements and numerical analyses. Field load tests were performed to verify the effect of the composite ground reinforced by stone columns in Kayan, Saudi. The settlement measured in the field test was compared with the settlement calculated by the Priebe method and the numerical analysis using ABAQUS. It is found that the settlement estimated using the Priebe method significantly overestimated the settlement measured in the field test. In addition, it is confirmed that consideration of confining effect exerted by surrounding adjacent stone columns in a numerical simulation is indispensable to estimate accurately the settlement of stone column composite ground.