• 한국지반공학회논문집
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• 제22권4호
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• pp.5-10
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• 2006

반무한 영역을 유한영역에 사영한 다음 반무한지반의 비선형동적응답해석에 대한 특수한 유한 차분법을 제안하였다. 해석대상의 주요 부분은 동일 길이로 하고, 주변은 축소, 사영함으로서 무한영역을 유한영역으로 변환 후 차분하였다. 우선 반무한 지반의 선형모델의 응답으로서 계산값과 이론값의 결과를 비교하였다. 선형모델에 대한 제안법의 계산결과는 Lamb의 해석결과와 양호하게 일치했다. 또 간단한 모델에 의한 선형, 비선형해석도 소규모 mesh에 의한 응답결과와 대규모 mesh에 의한 응답결과는 일치하고 제안법의 유효성을 나타내었다.

• 전기학회논문지
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• 제58권2호
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• pp.407-414
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• 2009

The foundation fieldbus(FF) is one of the fieldbuses most widely used for process control and automation, In order for system designer to optimize medium management, it is imperative to predict transmission delay time of data. In a former research, mathematical modeling to analyze transmission delay of FF token-passing system has been developed based on the assumption that a device node has only one priority data(1Q model), From 1Q model, all of the device nodes, which are connected on the FF system, are defined priority level in advance, and as system operates, data are generated based on given priority level. However, in practice, some non-periodic data can have different priority levels from one device. Therefore, new mathematical model is necessary for the case where different priority levels of data are created under one device node(2Q model). In this research, the mathematical model for 2Q model is developed using the equivalent queue model. Furthermore, the characteristics of transmission delay of 2Q model which is presented in this paper were compared with 1Q model. The validity of the analytical model was verified by using a simulation experiment.

• Earthquakes and Structures
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• 제12권2호
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• pp.165-175
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• 2017

This paper studies soil properties uncertainty and its implementation in the seismic response evaluation of structures. For this, response sensitivity of two 4- and 12-story RC shear walls to the soil properties uncertainty by considering soil structure interaction (SSI) effects is investigated. Beam on Nonlinear Winkler Foundation (BNWF) model is used for shallow foundation modeling and the uncertainty of soil properties is expanded to the foundation stiffness and strength parameters variability. Monte Carlo (MC) simulation technique is employed for probabilistic evaluations. By investigating the probabilistic evaluation results it's observed that as the soil and foundation become stiffer, the soil uncertainty is found to be less important in influencing the response variability. On the other hand, the soil uncertainty becomes more important as the foundation-structure system is expected to experience nonlinear behavior to more sever degree. Since full This paper studies soil properties uncertainty and its implementation in the seismic response evaluation of structures. For this, response sensitivity of two 4- and 12-story RC shear walls to the soil properties uncertainty by considering soil structure interaction (SSI) effects is investigated. Beam on Nonlinear Winkler Foundation (BNWF) model is used for shallow foundation modeling and the uncertainty of soil properties is expanded to the foundation stiffness and strength parameters variability. Monte Carlo (MC) simulation technique is employed for probabilistic evaluations. By investigating the probabilistic evaluation results it's observed that as the soil and foundation become stiffer, the soil uncertainty is found to be less important in influencing the response variability. On the other hand, the soil uncertainty becomes more important as the foundation-structure system is expected to experience nonlinear behavior to more sever degree. Since full probabilistic analysis methods like MC commonly are very time consuming, the feasibility of simple approximate methods' application including First Order Second Moment (FOSM) method and ASCE41 proposed approach for the soil uncertainty considerations is investigated. By comparing the results of the approximate methods with the results obtained from MC, it's observed that the results of both FOSM and ASCE41 methods are in good agreement with the results of MC simulation technique and they show acceptable accuracy in predicting the response variability.

• Geomechanics and Engineering
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• 제13권6호
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• pp.929-946
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• 2017

Composite foundation treated with compaction piles can eliminate collapsibility and improve the bearing capacity of foundation in loess area. However, the large number of piles in the composite foundation leads to difficulties in the analysis of such type of engineering works. This paper proposes two simplified methods to quantify the stability of composite foundation treated with a large number of compaction piles. The first method is based on the principle of making the area replacement ratios of the simplified model as the same time as the practical engineering situation. Then, discrete piles arranged in a triangular shape can be simplified in the model where the annular piles and compacted soil are arranged alternately. The second method implements equivalent continuous treatment in the pile-soil area and makes the whole treated region equivalent to a type of composite material. Both methods have been verified using treated foundation of an oil storage tank. The results have shown that the differences in the settlement values obtained from the water filled test in the field and those calculated by the two simplified methods are negligible. Using stability analysis, the difference ratios of the static and dynamic safety factors of the composite foundation treated with compaction piles calculated by these two simplified methods are found to be 3.56% and 5.32%, respectively. At the same time, both static and dynamic safety factors are larger than the general safety factor, which should be greater than or equal to 2.0 according to the provisions in civil engineering. This indicates that after being treated with compaction piles, the bearing capacity of the composite foundation is effectively improved and the foundation has enough safety reserve.

• Geomechanics and Engineering
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• 제16권6호
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• pp.589-597
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• 2018

Centrifuge model tests were used to simulate pile-raft composite foundation and pile-geogrid composite foundation with different pile spacing for researching the time effect of negative skin friction of rigid piles in high-speed railways. The research results show that the negative skin friction has a significant impact on the bearing capacity of composite foundation. Pile-raft composite foundation has higher bearing capacity compared to pile-geogrid composite foundation to reduce the effect of negative skin friction on piles. Both the foundation settlement and negative skin friction have significant time effect. The distribution of skin friction can be simplified as a triangle along the pile. The neutral point position moves deeper in the postconstruction stage at larger pile spacing. For pile-geogrid composite foundation, the setting of pile-cap affects the position of neutral point in the post-construction stage. Reinforced cushion with geotextile may promote the better performance of cushion for transmitting the loads to piles and surrounding soils. Arching effect in the cushion of the composite foundation is a progressive process. The compression of the rigid piles contributes less than 20% to 25% of the total settlement while the penetration of the piles and the compression of the bearing stratum below the pile tips contribute more than 70% of the total settlement. Some effective measures to reduce the settlement of soils need to be taken into consideration to improve the bearing capacity of pile foundation.

• 터널과지하공간
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• 제26권6호
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• pp.493-507
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• 2016

본 연구에서는 축소모형실험을 통해 석회암 공동 상부에 존재하는 구조물 기초의 안정성을 검토하였다. 공동의 형상은 단축장축비율 1/3인 타원형으로 가정하고, 공동의 심도, 위치, 경사, 크기, 개수를 변화시킨 5가지 그룹, 12개 모형들을 실험하였다. 실험결과로서 모형별 균열개시압력, 최대압력, 변형거동, 파괴양상, 침하곡선을 구하였으며, 공동의 제반 조건들이 기초의 안정성에 어떠한 영향을 미치는지를 알아보았다. 무공동 모형은 전단파괴를 보였으나, 공동 포함 모형들은 관입파괴만 발생한 경우, 전단파괴와 관입파괴가 함께 발생한 경우, 전단파괴가 이중으로 발생한 경우 등의 다소 복잡한 파괴형식을 보였다. 공동의 심도가 작을수록, 크기가 클수록, 개수가 많을수록 기초의 안정성은 감소하였다. 공동의 일부가 기초저면의 직하부에 놓일 때는 부등침하가 관찰되었고, 공동들의 분포상태에 따라 침하곡선은 다른 형태를 보였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.3-25
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• 2003

In this presentation, soil dynamics for vibrating machine foundation is briefly stated, and the result of a model pile test is presented. Analystical methods used in solving for the stiffness and damping factor for pile-soil system are also treated and the results of the test and the calculated values are compared.

• Earthquakes and Structures
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• 제15권2호
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• pp.215-225
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• 2018

To reach a better foundation treatment project, an optimized analysis of composite foundation was studied in the field of hydraulic engineering. Its unique characteristics in hydraulic engineering were concluded. And, the overall and detailed analysis of the composite foundation model established was carried out. The index parameters of the vertical reinforced rigid pile composite foundation were formulated. Further, considering the unique role of cushion in hydraulic engineering, its penetration and regularity were analyzed. Then, comparative and optimized analyses of cushion multistage physical dimensions and multistage material characteristics were established. The parameters of the piles distance were optimized and the multilevel scientific and reasonable parameters information was obtained. Based on the information of these parameters, the practical application was verified. It effectively supported the effective application of vertical reinforcement rigid pile composite foundation in hydraulic engineering. The service mechanism of composite foundation was fully analyzed.

• Asian Pacific Journal of Cancer Prevention
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• 제16권8호
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• pp.3153-3157
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• 2015

Background: Incidence and mortality rates for cancer have increased dramatically in the recent 30 years in Taiwan. However, not all patients receive treatment. Treatment refusal might impair patient survival and life quality. In order to improve this situation, we proposed this study to evaluate factors that are related to refusal of treatment in cancer patients via a cancer case manager system. Materials and Methods: This study analysed data from a case management system during the period from 2010 to 2012 at a medical center in Northern Taiwan. We enrolled a total of 14,974 patients who were diagnosed with cancer. Using the PRECEDE Model as a framework, we conducted logistic regression analysis to identify independent variables that are significantly associated with refusal of therapy in cancer patients. A multivariate logistic regression model was also applied to estimate adjusted the odds ratios (ORs) with 95% confidence intervals (95%CI). Results: A total of 253 patients (1.69%) refused treatment. The multivariate logistic regression result showed that the high risk factors for refusal of treatment in cancer patient included: concerns about adverse effects (p<0.001), poor performance(p<0.001), changes in medical condition (p<0.001), timing of case manager contact (p=.026), the methods by which case manager contact patients (p<0.001) and the frequency that case managers contact patients (${\geq}10times$) (p=0.016). Conclusions: Cancer patients who refuse treatment have poor survival. The present study provides evidence of factors that are related to refusal of therapy and might be helpful for further application and improvement of cancer care.

• 한국농공학회지
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• 제36권2호
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• pp.67-78
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• 1994

This is a fundamental study aiming at scrutinizing the effect of reinforcement and deformation characteristics of soft clayey foundation improved by vanous technical treatments. Among many methods proposed thus far, geotextile was selected for the purpose of improvement of the model soil foundation on which plate loading test was subsequently performed. Loading test has been carried out with the variation of the location and number of covering layers of geotextile, and actual values for ground deformation and geotextile effect were secured. As for technique on deformation analysis, elasto-plastic model for soil, elastic model for sand, and beam theory for geotextile were coupled with satisfactory results between observed and numerical values.