• Journal of the Korean Society of Safety
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• v.13 no.3
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• pp.135-142
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• 1998

This paper is to investigate the failure surface and modes in a soil mass by a excavation of the model ground. To study the failure surface for the excavated slope, centrifugal model tests were performed by changing the angle of the excavated slope(50, 75, $90^{\circ}$) and the ground condition($D_r$=60, 90%, dry and submerged ground). Excavation was simulated during the centrifuge tests by operating a valve that allowed the zinc chloride solvent to drain from the excavation. Results of model tests were compared with those obtained with theoretical solutions using limit equilibrium analysis method. The results of model tests show that, there is a failure to create a straight line in the low angle of excavated surface and a create a circle as the angle increases. Also, as the angle of excavated surface is increasing, the angle of the failure surface increases. The failure length in the submerged ground increases approximately 1.10~1.34 times more than that of the dry ground.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.201-204
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• 2010

Earthquake load to design a structure has been calculated from a fixed base SDOF model using amplified surface accelerations along soft soil layers. But the method dose not consider a soil-structure interaction. Centrifugal experiments that were consisted of soil, a shallow foundation and a structure were performed to find the effects of soil-structure interaction. The experiments showed that mass and stiffness of the foundation affected a response of the structure and nonlinear behavior of soil near the foundation. And a rocking displacement caused by overturning moment affected the response and increases a damping effect. In this study, the centrifugal experiment was simulated as a two dimensional finite element model. The finite element model was used for nonlinear time domain analysis of the OpenSees program. The numerical model accurately evaluated the behaviors of soil and the foundation, but the rocking effect and the behavior of structure were not described.

• Journal of Industrial Technology
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• v.25 no.A
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• pp.57-65
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• 2005

In this paper, for the highly plastic marine soft clay distributed in west and southern coast of Korean peninsula of Kwangyang and Busan New Port areas, correlation between compression index and other indices representing geotechnical engineering properties such as liquid limit, void ratio and natural water content were analyzed. Appropriate empirical equations of being able to estimate the compressibility of clays in the specific areas were proposed and compared with other existing empirical ones. For analyses of the data and test results, data for marine clays were used from areas of the South Container Port of the Busan New Port, East Breakwater, Passenger Quay, Jungma Reclamation and Reclamation Containment in the 3rd stage in Kwangyang. In order to find the best regression model by using the commercially available software, MS EXCEL 2000, results obtained from the simple linear regression analysis, using the values of liquid limit, initial void ratio and natural water content as independent variables, were compared with the existing empirical equations. Multiple linear regression was also performed to find the best fit regression curves for compression index and other soil properties by combining those independent variables. On the other hands, another software of SPSS for non-linear regression was used to analyze the correlations between compression index and other soil properties.

• Journal of the Korean GEO-environmental Society
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• v.16 no.12
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• pp.23-35
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• 2015

Nonlinear soil behavior before failure under dynamic loading is often implemented in a numerical analysis code by a mathematical fitting function model with Masing's rule. However, the model may show different behavior with an experimental results obtained from laboratory test in damping ratio corresponding secant shear modulus for a certain shear strain rage. The difference may come from an unique soil characteristics which is unable to implement by using the existing mathematical fitting model. As of now, several fitting models have been suggested to overcome the difference between model and real soil behavior but consequence of the difference in dynamic analysis is not reviewed yet. In this paper, the effect of the difference on site response was examined through nonlinear response history analysis. The analysis was verified and calibrated with well defined dynamic geotechnical centrifuge test. Site response analyses were performed with three mathematical fitting function models and compared with the centrifuge test results in prototype scale. The errors on peak ground acceleration between analysis and experiment getting increased as increasing the intensity of the input motion. In practical point of view, the analysis results of accuracy with the fitting model is not significant in low to mid input motion intensity.

• The Korean Journal of Physiology
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• v.15 no.1
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• pp.53-59
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• 1981

In the present study, an effort was directed to elucidate the effect of osmolality on the absorption of ethanol in rabbits. A single dose of 13.67 ml(2. 16 gm ethanol/kg BW) of hypo-, iso-hyphen and hypertonic ethanol per kg BW was administered into the stomach to albino rabbits and the experiment was performed at 30 th, 60 th and 120 th minute. The blood ethanol level was determined by the method of Williams et al, and hematocrit(Hct) was determined by the conventional Hct centrifuge and reader. The results are summarized as follow. The blood ethanol level showed the highest value at 60 min after the ethanol ingestion in the hypo- and isotonic groups, $171.3{\pm}13.3\;mg%$ and $204.5{\pm}23.0\;mg%$, respectively, but in the hypertonic group, the highest value was observed at 120min after the ingestion. The absorption rate of ethanol between 0 to 30 min after the ingestion of hypo- and isotonic ethanol was $88.54{\pm}12.04$ and $94.73{\pm}8.33\;mg/min$, respectively, but a decreased value of $44.72{\pm}6.69\;mg/min$ was noted after hypertonic ethanol ingestion comparing with hypo- and isotonic groups, The Hct value after hypo- and isotonic ethanol ingestion was decreased at 30 min but returned to the control level at 120 min. In contrast with hypo- and isotonic ethanol ingestion, hypertonic ethanol ingestion produced an increase of the Hct value at 30 min and returned to the control level at 120 min. The heart rate was increased but the respiratory rate was decreased after ethanol ingestion regardless of the osmolality.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.38 no.2
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• pp.133-138
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• 2012

The purpose of this study was to examine the correlation between physical properties of dried coacervate films and dry feel for shampoo composition. Simple shampoo compositions were made of two different cationic charge density polymers in the same surfactant compositions. The simple shampoo compositions were diluted with distilled water to make coacervate. Formed coacervate was collected by centrifuge (3,000 rpm, 30 min). Coacervate was coated on the glass plates and dried in drying oven (for 1 h, $50^{\circ}C$) to make the thin film. We carried out an experiment on measurement of contact angle, moisture loss ratio and SEM image analysis of the dried coacervate film. Dry feelings of the shampoos were evaluated by panel using hair tresses. Results show that the properties of dried coacervate films affect the dry feel of the after shampooing.

• Journal of Korean Tunnelling and Underground Space Association
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• v.5 no.2
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• pp.199-207
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• 2003

Tunnel modelling in the field of geotechnical engineering essentially requires models of tunnelling machines and the simulation of tunnelling processes to clarify the detailed behaviour of tunnel construction. Modern advanced mechatronics, including construction processes, machinining and control technologies, are making it possible to fabricate such models. These technologies, however, are essentially developed in a gravity field condition and are needed to examine in a 1g or cenrifuge field condition. This paper presents the simulation method for tunnelling processes and the design method for tunnelling machines with special reference to the problem of earth pressure acting on the lining of a shield tunnel. The paper then introduces and verifies the design method for tunnelling machines in the 1g field by means of checking the reproduceability of experiment data and their comparison with data in the field.

• Journal of the Korean Geotechnical Society
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• v.37 no.6
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• pp.39-50
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• 2021

Recently, as the occurrence of earthquakes with a magnitude of 5.0 or higher in Korea increases, many studies and interests in seismic design are increasing. A lot of damage was caused by the Pohang earthquake in 2017, and port facilities such as a breakwater were also damaged. This study analyzed the dynamic behavior of the upright breakwater, an external facility, based on a centrifugal model experiment. A series of centrifugal model test was conducted by three different seismic waves such as Pohang Earthquake Wave, Artificial Wave I, and II. As a result, the dynamic behavior of upright breakwater was analyzed. The review showed that acceleration amplification tends to be suppressed as breakwater foundation ground increases support and stiffness through DCM reinforcement and riprap replacement.

• The Journal of Internal Korean Medicine
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• v.29 no.2
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• pp.318-333
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• 2008

Objectives : In this study, the author tried to examine whether Cheogjogupye-tang (淸燥救肺湯, CGPT) and Yieum-jeon (理陰煎, YEJ) significantly affect in vitro and in vivo mucin secretion, MUC5AC gene expression in airway epithelial cells and contractility of isolated tracheal smooth muscle of rabbit. Materials and Methods : For in vitro experiment, confluent hamster tracheal surface epithelial (HTSE) cells were chased for 30 minutes in the presence of CGPT and YEJ to assess the effects of the agents on mucin secretion by enzyme-linked immunosorbent assay (ELISA), with removal of oriental herbal medicine extract from each agent-treated sample by centrifuge microfilter. Also, the effects of the agents on TNF-alpha or EGF-induced MUC5AC gene expression in human airway epithelial cells (NCI-H292) were investigated. Possible cytotoxicities of the agent were assessed by examining both LDH release from HTSE cells and the rate of survival and proliferation of NCI-H292 cells. For in vivo experiment, hypersecretion of airway mucin and goblet cell hyperplasia was induced by exposure of rats to $SO_2$ over 3 weeks. Effects of CGPT and YEJ orally administered for 1 week on in vivo mucin secretion from tracheal goblet cells of rats and hyperplasia of goblet cells were assessed using ELISA and histological analysis after staining the epithelial tissue with alcian blue, respectively. Also, the effects of CGPT and YEJ on contractility of isolated tracheal smooth muscle were investigated. Results : (1) CGPT significantly inhibited in vitro mucin secretion from cultured HTSE cells. However, YEJ did not affect in vitro mucin secretion; (2) CGPT and YEJ did not affect hypersecretion of in vivo mucin and hyperplasia of tracheal goblet cells; (3) CGPT and YEJ slightly increased the expression levels of TNF-alpha or EGF-induced MUC5AC gene in NCI-H292 cells; (4) CGPT and YEJ inhibited acetylcholine-induced contraction of isolated tracheal smooth muscle of rabbit; (5) CGPT and YEJ did not affect LDH release from HTSE cells and the survival and proliferation of NCI-H292 cells. Conclusion : The results from the present study suggest that CGPT and YEJ mainly affect the expression of mucin gene rather than secretion of mucin and do not show remarkable cytotoxicity to respiratory epithelial cells.

• Journal of the Korean Geotechnical Society
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• v.38 no.9
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• pp.5-17
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• 2022

Recently, several studies have been conducted on virtual fixed-point and elastic soil spring methods to simulate the soil-pile interaction in response to spectrum analysis of pile-supported structures. However, the soil spring stiffness has not been properly considered due to the seismic load magnitude, and studies on the response spectrum analysis of pile-supported structures considering this circumstance are inadequate. Therefore, in this study, the response spectrum analysis was performed considering the soil spring stiffness according to the seismic load magnitude, and the dynamic behavior of the pile-supported structure was evaluated by comparing it with existing virtual fixed-point and elastic soil spring methods. Comparing the experiment and analysis, the moment differences occurred up to 117% and 21% in the virtual fixed-point and elastic soil spring models, respectively. Moreover, when the analysis was performed using an API p-y curve considering the soil spring stiffness according to the seismic load magnitude, the moment difference between the experiment and analysis was derived at a maximum of < 4%, and it is the most accurate method to simulate the experimental model response.