• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.414-419
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• 2006

In this paper, the numerical results using the Mohr-Coulomb and the Duncan-Chang models, on the stresses and strains of a tunnel under a deep open-cut site and the surrounding ground, were compared with each other. The Mohr-Coulomb model produced larger values than the Duncan-Chang model in stress and displacement of tunnel and ground.

• Journal of the Korean GEO-environmental Society
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• v.19 no.12
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• pp.47-58
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• 2018

Duncan & Chang(1970) proposed the Duncan-Chang model that a linear relation of transformed stress-strain plots was reconstituted from a nonlinear relation of stress-strain curve of triaxial compression test using hyperbolic theory so as to estimate an initial tangent modulus and ultimate deviator stress for the soil specimen. Although the transformed stress-strain plots show a linear relationship theoretically, they actually show a nonlinearity at both low and high values of strain of the test. This phenomenon indicates that the stress-strain curve is not a complete form of a hyperbola. So, if linear regression analyses for the transformed stress-strain plot are performed over a full range of strain of a test, error in the estimation of their linear equations is unavoidable depending on ranges of strain with non-linearity. In order to reduce such an error, a modified regression analysis method is proposed in this study, in which linear regression analyses for transformed stress-strain plots are performed over the entire range of strain except the range the non-linearity is shown around starting and ending of the test, and then the initial tangent modulus and ultimate deviator stresses are calculated. Isotropically consolidated-drained triaxial compression tests were performed on compacted weathered soil with a modified Proctor density to obtain their model parameters. The modified regression analyses for transformed stress-strain plots were performed and analyzed results are compared with results estimated by 2 points method (Duncan et al., 1980). As a result of analyses, initial tangent moduli are about 4.0% higher and ultimate deviator stresses are about 2.9% lower than those values estimated by Duncan's 2 points method.

• Geomechanics and Engineering
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• v.18 no.3
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• pp.291-298
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• 2019

In order to study the mechanical properties of rock salt, triaxial compression tests under different temperatures and confining pressure are carried out on rock salt specimens, the influence of temperature and confining pressure on the mechanical properties of rock salt was studied. The results show that the temperature has a deteriorative effect on the mechanical properties of rock salt. With the increase of temperature, the peak stress of rock salt decreases visibly; the plastic deformation characteristics become much obvious; the internal friction angle increases; while the cohesion strength decreases. With the increase of confining pressure, the peak stress and peak strain of rock salt will increase under the same temperature. Based on the test data, the Duncan-Chang constitutive model was modified, and the modified Duncan-Chang rock salt constitutive model considering the effect of temperature and confining pressure was established. The stress-strain curve calculated by the modified model was compared with the stress-strain curve obtained from the test. The close match between the test results and the model prediction suggests that the modified Duncan-Chang constitutive model is accurate in describing the behavior of rock slat under different confining pressure and temperature conditions.

• Geomechanics and Engineering
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• v.10 no.1
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• pp.37-48
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• 2016

The hyperbolic stress-strain model has been shown to be valid for modeling nonlinear stress-strain behavior for rockfill materials. The Duncan-Chang nonlinear constitutive model was adopted to characterize the behavior of the modeled rockfill materials in this study. Accurately estimating the model parameters of rockfill materials is a key problem for simulating dam deformations during both the dam construction period and the dam operation period. In order to estimate model parameters, triaxial compression experiments of rockfill materials were performed. Based on a genetic algorithm, the constitutive model parameters of the rockfill material were determined from the triaxial compression experimental data. The investigation results show that the predicted strains provide satisfactory precision when compared with the observed strains and the strains forecasted by a gradient-based optimization algorithm. The effectiveness of the proposed inversion procedure of model parameters was verified by experimental investigation in a laboratory.

• Journal of the Korean GEO-environmental Society
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• v.19 no.4
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• pp.27-32
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• 2018

There were many ground excavation projects from past to present to make effective use of the limited land. And it is very important to predict the ground behavior depending on construction stage for ground excavation. Excavation of the ground involves changes in the stress and displacement of the ground around the excavated surface. Thus it affects the stability of the adjacent structure as well as the excavated surface. Therefore, it is very important to predict the ground behavior and stability of adjacent structure. And nowadays, numerical analysis methods are most often used to predict the effects of ground excavation. Recent, improvements of numerical analysis programs, along with improved computer performance, have helped solve complicated ground problems. However, except some specialized numerical analysis, most numerical analysis often predicts larger excavation floor displacement than field data due to adopt the Mohr-Coulomb analysis model. As a result, it raise the problem that increasing the amount of support on ground and structure. In this study, ground behavior analysis depending on analysis model (Mohr-Coulomb, Duncan-Chang, Modified Mohr-Coulomb and Hardening Soil model) has been carried out through the numerical analysis. When numerical analysis is carried out, this study is expected to be used as a basic data for adopting a suitable analysis model in various ground excavation project.

• Geomechanics and Engineering
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• v.16 no.3
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• pp.309-320
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• 2018

In this paper, a numerical study using finite element method with considering soil-structure interaction was conducted to investigate the stress and deformation behavior of a sheet pile wall structure. In numerical model, one of the nonlinear elastic material constitutive models, Duncan-Chang E-v model, is used for describing soil behavior. The hard contact constitutive model is used for simulating the behavior of interface between the sheet pile wall and soil. The construction process of excavation and backfill is simulated by the way of step loading. We also compare the present numerical method with the in-situ test results for verifying the numerical methods. The numerical analysis showed that the soil excavation in the lock chamber has a huge effect on the wall deflection and stress, pile deflection, and anchor force. With the increase of distance between anchored bars, the maximum wall deflection and anchor force increase, while the maximum wall stress decreases. At a low elevation of anchored bar, the maximum wall bending moment decreases, but the maximum wall deflection, pile deflection, and anchor force both increase. The construction procedure with first excavation and then backfill is quite favorable for decreasing pile deflection, wall deflection and stress, and anchor forces.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.2
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• pp.1-8
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• 2013

This study was performed for the purpose of analyzing the effect of tide on the stress-strain behavior in the boundary surface of sea dike embankment. Tide is a dynamic condition, but there are not suitable numerical models to solve the dynamic embankment condition caused by tide. So the analysis was simplified to quasi dynamic as follow. First, seepage by tide was analyzed according to elapsed time, and the results of the analysis at every hour during one periodic cycle time of 12 hours were applied to the pore water pressure conditions of stress-strain analysis with hyperbolic model by Duncan and Chang. The place at which maximum shear strain took place in the analysis result moved up and down repeatedly along the boundary of the dredged sand fill section and the crashed stone filter section. The value of maximum shear strain was large at high water level of tide. This result means that contraction and relaxation occur in turn repeatedly at every specific position along the boundary, and the repeated action compact loose position with sand moved down from the upper position by gravity. The experiment with the small sea dike model showed the result consistent with the numerical analysis. The surface of sea side on the dike collapsed at high water level after a couple of repetition of the rising and falling of water.

• Journal of Animal Science and Technology
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• v.52 no.1
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• pp.51-56
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• 2010

This study was conducted to clarify the characteristics of Holstein dairy cow's vocalization in postpartum related with calf isolation. Vocalizations of 16 individuals of cows were recorded 6 hours per day (1:00am~4:00am and 1:00pm~4:00pm) using digital recorder and microphone during October 2008 and May 2009. Vocalizations were divided into 4 types. Characteristics of frequency, intensity and duration were analyzed by GLM (general linear model) and Duncan's multi-test. There were significant differences in frequency and intensity based on analyses of spectrogram and spectrum among 4 types of vocalizations. Frequencies of vocalizations were dramatically decreased on 2nd and 3rd day. Vocalization would be important factor affecting the motheryoung bond in Holstein dairy cattle.

• Journal of the Korean Society of Physical Medicine
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• v.5 no.4
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• pp.551-558
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• 2010

연구목적 : 미세전류 자극이 아주반트로 류마티스 관절염을 유발한 실험동물의 염증반응과 통증에 미치는 효과를 알아보기 위하여 실험동물의 발허리발가락관절내 염증반응 정도를 나타내는 인터루킨-6(interleukin-6)의 발현과 핫플레이트(hot plate)를 이용한 발도피지연시를 측정하여 미세전류의 효과에 대하여 알아보고자 하는데 목적이 있다. 연구방법 : 실험동물은 무작위로 대조군(n=18)과 미세전류를 적용한 실험군(n=18)으로 구분하였고, 각 군당 6마리씩 1일군, 7일군, 14일군으로 배정하였다. 류마티스 관절염 유발후 1일, 7일, 14일에 모든 실험동물의 열통각 역치를 나타내는 발도피지연시와 발허리발가락관절내 인터루킨-6의 발현정도를 측정하였다. 각 집단 내의 기간에 따른 발도피지연시와 인터루킨-6의 면역반응성은 일원배치 분산분석을 실시하였고, 사후분석으로는 Duncan의 다중범위검정을 실시하였다. 실험군과 대조군을 비교하기 위하여 독립표본 t-test를 실시하였다. 연구결과 : 실험결과는 다음과 같다. 1) 아주반트 주사 1일후, 실험군과 대조군에서 인터루킨-6 면역반응성과 발도피지연시는 비슷한 양상을 보였다. 2) 인터루킨-6 면역반응성은 아주반트 주사 7일, 14일 후 대조군이 실험군보다 유의하게 증가되었다(p<.05). 3) 발도피지연시는 아주반트 주사 7일, 14일 후 실험군이 대조군보다 유의하게 증가되었다(p<.05). 결론 : 이상의 결과로부터, 미세전류 자극이 아주반트로 유발된 류마티스관절염 모델에서 활액 조직내 염증반응을 감소시키고 열통각역치는 증가되는 것을 알 수 있었다.

• Journal of Information Technology Applications and Management
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• v.15 no.3
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• pp.79-90
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• 2008

With the corporate environment nowadays being surrounded by plenty of information, the sharing of information among businesses through mutual cooperation tops the list of hot issues. Predictions of demands from the customer, business, or consumer by sharing information can affect the inventory and order production system. However, notwithstanding the importance of sharing information, empirical studies on quantitative use of information still remain insufficient in spite of many a discussion now being made on the sharing of information. This paper proposes to examine the ways meteorological information may affect the rises in the achievements of supply chains in distributive businesses, the kind of information that noticeably affects the consumer behavioral patterns in the distributive businesses but rarely perceived as a form of information shared by businesses. This study is based on a model in which meteorological information has been added as the one used to predict demands, after the beer distribution game has been modified to fit the current status, and simulations under an assumptive situation, where decisions are made on a daily basis, were conducted 50 times for a period of 1000 days for the generalization of the results, while at the same time a Duncan Test was conducted to determine the threshold to use the meteorological information that will be most profitable to the retailer, wholesaler, supplier and the supply chain as a whole. Our findings indicate that corporations have thresholds that vary from business to business depending upon the ratio of backlog costs to inventory costs. At the same time, our findings also show that there existed effective thresholds depending upon the ratio of backlog costs to inventory costs for the performance of the overall supply chain.