• Journal of the Korean Geotechnical Society
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• 제38권5호
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• pp.5-17
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• 2022

A pile is a type of medium for constructing superstructures in weak geotechnical conditions. A pretensioned spun high-strength concrete (PHC) pile is composed of high-strength concrete with a specified strength greater than 80 MPa. Therefore, it has advantages in resistance to axial and bending moments and quality control and management since it is manufactured in a factory. However, the skin friction of a pile, which accounts for a large portion of the pile bearing capacity, is only approximated using empirical equations or standard penetration test (SPT) N-values. Particularly, there are some poor research results on the pile-soil interface under the seismic loads in Korea. Additionally, some studies do not consider geoenvironmental elements, such as groundwater pH values. This study performs sets of cyclic simple shear tests using submerged concrete specimens for 1 month to consider pH values of groundwater and clay specimens composed of kaolinite to generate a pile-soil interface. 0.2 and 0.4 MPa of normal stress conditions are considered in the case of pH values. The disturbed state concept is employed to express the dynamic behavior of the interface, and the disturbed function parameters are newly suggested. Consequently, the largest disturbance increase under basic conditions is observed, and an early approach to the failure under low normal stress conditions is presented. The disturbance function parameters are also suggested to express this disposition quantitatively.

• Tuberculosis and Respiratory Diseases
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• 제61권3호
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• pp.265-272
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• 2006

Background: Chest wall deformities such as kyphoscoliosis, thoracoplasty, and fibrothorax cause ventilatory insufficiency that can lead to chronic respiratory failure, with recurrent fatal acute respiratory failure(ARF). This study evaluated the frequency and outcome of ARF, the physiologic status, and the long-term prognosis of these patients. Methods: Twenty-nine patients with chest wall disorders, who experienced the first requirement of ventilatory support from ARF were examined. The mortality and recurrence rate of ARF, the pulmonary functions with arterial blood gas analysis, the efficacy of home oxygen therapy, and the long-term survival rate were investigated. Results: 1) The mortality of the first ARF was 24.1%. ARF recurred more than once in 72.7% of the remaining 22 patients, and overall rate of successful weaning was 73.2%. 2) Twenty-two patients who recovered from the first ARF showed a restrictive ventilatory impairment with a mean FVC and TLC of 37.2% and 62.4 % of predicted value, respectively, and a mean $PaCO_{2}$ of 57mmHg. Among the parameters of pulmonaty functions. the FVC(p=0.01) and VC(p=0.02) showed a significant correlation with the $PaCO_{2}$ level. 3) There were no significant differences between the patients treated with conservative medical treatment only and those with additional home oxygen therapy due to significant hypoxemia in the patients with recurrent ARF and the mortality. 4) The 1, 3, 5-year survival rates were 75%, 66%, and 57%, respectively, in the 20 patients who had recovered from the first ARF, excluding the two patients managed by non-invasive nocturnal ventilatory support. Conclusion: These results suggest that active ventilatory support should be provided to patients with ARF and chest wall disorders. However, considering recurrent ARF and weak effect of home oxygen therapy, non-invasive domiciliary ventilation is recommended in those patients with these conditions to achieve a better long-term prognosis.

• Journal of the Korean Geotechnical Society
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• 제21권4호
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• pp.65-70
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• 2005

Many case histories of re-liquefaction phenomena seem to support the idea that sand deposits, if they once have been liquefied, could be reliquefied again by a subsequent earthquake even though the earthquake is smaller than the previous one. The magnitude of the strains induced in the initial liquefaction has a significant influence on the resistance of the sample to re-liquefaction. The deposits undergoing liquefaction experience large shear strain during liquefaction. And this previous strain changes the microstructure into highly anisotropic structure such as columnlike structure and connected voids. This type of anisotropy is so unstable that it can reduce re-liquefaction resistance. It is blown that the extent of anisotropic structural change depends on the gradation characteristics of ground. The purpose of this study is to estimate the correlation between the gradation characteristics of the sand and the ratio of re-liquefaction resistance to liquefaction resistance. In this study, 1-g shaking table tests were carried out on five different kinds of sands. During the tests the values of excess pore pressure at various depths and surface settlements were measured. Re-liquefaction resistances were not affected by the initial void ratio and the effective confining pressures, and the deposits of all test sands which had once been liquefied were reliquefied in the cyclic loading number below 1 to 1.5. The ratio of re-liquefaction resistance to liquefaction resistance linearly decreased as $D_{10}/C_u$ increased, and was constant as about 0.2 above the value of $D_{10}/C_u$, 0.15 mm.

• Journal of the korean academy of Pediatric Dentistry
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• 제30권2호
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• pp.196-203
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• 2003

The application of sealants is a highly technique-sensitive procedure, requiring an extremely dry field prior to placement. Moisture contamination of the etched enamel surface before sealant placement is cited as the main reason for sealant failure. The purpose of this study was to evaluate the effects of different methods of sealant application on the shear bond strength of sealants to enamel. In groups 1, 2, 3, 4 Teethmate(unfilled sealant) was used, while Ultraseal XTplus(filled sealant) was used in groups 5, 6, 7, 8. Groups 1 and 5(control) were acid etched for 15 seconds using 35% phosphoric acid, washed and then dried. In groups 2, 6 drying agents were applied, and in groups 3, 7 bonding agents were applied and light cured. In groups 4 and 8 both drying agent and bonding agent were applied. Then sealant was cured to the specimen using molds 3mm in diameter and 2mm in height. Thermocycling was performed and shear bond strength was finally measured. The following results were obtained : 1. Groups using filled sealant(groups 5, 6, 7, 8) showed higher shear bond strengths compared to groups using unfilled sealant(groups 1, 2, 3, 4). 2. Among groups using unfilled sealant(groups 1, 2, 3, 4), groups 2, 3, 4 showed significantly higher shear bond strength compared to group 1(p<0.05). There were no significant differences among groups 2, 3 and 4. 3. There were no significant differences(p>0.05) among groups using filled sealant(groups 5, 6, 7, 8). 4. When modes of fracture were examined, cohesive failure was observed in groups 2, 3 and 4.

• The Korean Journal of Food And Nutrition
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• 제14권1호
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• pp.34-39
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• 2001

The purpose of this study was to examine physical properties of the addition of green tea powder on bread flour and dough rheology of white pan bread. Three levels(0.1, 0.5 and 1.0% ) of each green tea powder with bread flour were tested for their effects in dough mixing using rapid disco analyzer, alveogram and farinogram. Addition of green tea powder tended to reduce initial pasting temperature and increase peak viscosity, break down and set back. L(extensibility) and G(swelling index) value in alveogram showed decrement with increasing green tea powder. These meant that the volume of white pan bread would show same tendency. The use of green tea powder increased consistency and water absorption of the bread flour but decreased development time, salability and degree of softening on farinogram. White pan bread with green tea powder had higher value of hardness and springness than without it. Sensory evaluation determined that the white pan bread with 0.5% green tea powder had the highest score.