현장시험결과를 이용한 지반의 변형계수 추정에 관한 연구

천병식 ( Chun Byung-sik ),서덕동 ( Seo Deok-dong ),이승현 ( Lee Soung-hyun ) 한국구조물진단유지관리공학회 2004 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.8 No.2

본 연구에서는 국내 14개 현장에서 SPT N치 그리고 베인전단시험과 콘관입시험로 구한 비배수전단강도(c_u)의 데이터를 공내재하시험(LLT) 결과와 비교 · 분석하여 그 상관성에 대하여 파악해 보았다. 특히, 지반을 점성토, 모래 그리고 토사와 암반의 중간지반인 IGM(Intermediate Geomaterials)으로 분류하여 그 특성과 적용성에 관하여 분석하였다. 즉, 기존의 제안식인 SPT N치와 변형계수 관계식 그리고 비배수전단강도와 변형계수의 관계식을 현장시험결과와 비교하여 적용성을 평가하였으며, 시험결과를 토대로 점성토, 모래, IGM 지반별로 새로운 추정식을 제안하였다. The deformation modulus is an important variable which is used to predict settlement of structures, analyze horizontal directions of piles and design roads. Though many equations about standard penentration test N-value and undrained shear strength were suggested to predict deformation modulus, these equations are not reasonable in demestic areas. Therefore, in this study, with field test results, reasonable equations in domestic area are suggested and the problems are grasped. Finally, new equations are suggested to estimate deformation modulus.

Constitutive Behaviour of Fine Grained Soils of Vijayawada Region

Sateesh Narepalem,Venkata Rama Subba Rao Godavarthi 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.6

A comprehensive study was carried out to examine the suitability of hyperbolic model to establish undrained stress–strain (σ-ε) response of cohesive soils of Vijayawada region, India. The majority of locations in this region covered with cohesive soils. Standard penetration test (SPT) is the most commonly used in-situ test conducted as a part of geotechnical investigation in this region. In this paper a simplified hyperbolic model was proposed to evaluate the σ-ε curve in terms of SPT value (N value). The present study aims on predicting undrained shear strength/undrained cohesive strength (Cu) and elastic modulus (E) from N value. Empirical correlations would permit consulting engineers to rapidly estimate Cu and E using N value.

암버력이 혼재된 토사의 토량환산계수 변화에 관한 실험적 연구

박영목 대한토목학회 2012 대한토목학회논문집 C Vol.32 No.5

본 연구는 밀양과 울산지역에 건설 중인 2개소의 도로현장을 택하여 현장시험을 통한 암석과 토사가 혼재되어 있는 경우에 대한 토량환산계수의 특정 및 단위중량의 변화 등을 검토한 것이다. 시험 결과, 암석과 토사가 동등한 비율로 혼합한 경우에 최대 단위중량을 얻을 수 있었으며, 암석만의 경우와 비교한 결과 2개소의 현장에서 각각 19%와 18%의 단위중량이 증가되었다. L값은 표준품셈에서 제시된 값보다 4~11% 크게 나타났으나, C값은 약 13~20% 낮게 나타냄을 알 수 있었다. 이는 최근 다짐장비의 대형화 및 다짐작업의 합리화에 기인되는 현상이므로 토공작업에서 이에 대한 고려가 있어야 할 것으로 판단된다. 또한 운반 시 암석과 토사가 5:5로 혼합되었을 때 가장 높은 단위중량을 나타내어 유리한 조건이 됨을 알 수 있었다. Field and laboratory tests were performed to investigate the swelling(L value) and shrinkage modulus (C value) of soil and rock mixtures using 2 sites. According to test results, when disturbed soil and rock were mixed with same amount (5 : 5), the maximum density was achieved and showed 19% and 18% increased at each site comparing with the unit weight of rock only. Since measured L values of mixtures were overestimated about 4 to 11% compare to estimated values based on the conventional method. While C values were underestimated about 13~20% compare to conventional values due to the development of compacting equipments and effective construction management. When rock and soil were mixed in the ratio of 5 to 5, the unit weight of the mixture was higher than that of other mixtures and rock or soil only.

중립면 대칭 기능경사재료 보의 자유진동 변화도

뉴엔 반 뚜안,노혁천 한국전산구조공학회 2018 한국전산구조공학회논문집 Vol.31 No.3

In this paper, a scheme for the evaluation of variability in the eigen-modes of functionally graded material(FGM) beams is proposed within the framework of perturbation-based stochastic analysis. As a random parameter, the spatially varying elastic modulus of FGM along the axial direction at the mid-surface of the beam is chosen, and the thru-thickness variation of the elastic modulus is assumed to follow the original form of exponential variation. In deriving the formulation, the first order Taylor expansion on the eigen-modes is employed. As an example, a simply supported FGM beam having symmetric elastic modulus with respect to the mid-surface is chosen. Monte Carlo analysis is also performed to check if the proposed scheme gives reasonable outcomes. From the analyses it is found that the two schemes give almost identical results of the mean and standard deviation of eigen-modes. With the propose scheme, the standard deviation shape of respective eigen-modes can be evaluated easily. The deviated mode shape is found to have one more zero-slope points than the mother modes shapes, irrespective of order of modes. The amount of deviation from the mean is found to have larger values for the higher modes than the lower modes. 본 논문에서는 기능경사재료 보 고유벡터의 변화도 산정을 위한 해석 정식화를 섭동법에 기초하여 제시한다. 불확실인수로는 기능경사재료 보의 중앙면에서 보의 축을 따르는 방향으로 공간적 불확실성을 가지는 재료탄성계수를 택하였다. 두께 방향으로의 탄성계수 변화는 원래의 지수함수를 따르는 것으로 가정하였다. 정식화에서는 고유벡터에 대한 선형 Taylor전개를 적용한다. 수치예제로는 보의 중앙면에 대하여 대칭인 탄성계수를 가지는 단순지지 보를 택하였다. 몬테카를로 해석을 함께 수행하여 제안한 정식화가 합리적인 결과를 주는지 확인하였다. 해석을 통하여 몬테카를로 해석과 제안된 방법에 의한 결과가 고유모드의 평균 및 표준편차에서 거의 동일한 결과를 제시함을 볼 수 있었다. 제안된 방법을 통하여 고유모드의 표준편차 형상을 쉽게 산정할 수 있다. 고유모드의 평균중심 변화량은 고유모드의 차수에 관계없이 그 고유모드 대비 한 개가 더 많은 경사 0인 점을 가지게 된다. 또한 평균 고유모드형상으로부터의 변화량은 저차 모드보다 고차모드에서 더 크게 나타남을 알 수 있었다.

롤투롤 시스템에서 소재의 기계적 물성변화를 포함한 권취공정의 장력해석

이종수(J. S. Lee),신기현(K. H. Shin),강현규(H. K. Kang),박성식(S. S. Park) 한국정밀공학회 2010 한국정밀공학회 학술발표대회 논문집 Vol.2010 No.11월

NOTE ON THE MODULUS METHOD IN R<SUP>n</SUP>

Chung, Bo-Hyun 충청수학회 2003 충청수학회지 Vol.16 No.2

In this note, we introduce the concept of the modulus of a curve family in $R^n$ and examine some basic properties. And we study the boundary behavior of quasiconformal mappings on a domain $D{\subset}\bar{R}^n$ and present some geometric applications.

An Estimation of VaR in stock markets using transformations

여인권,정추미 한국데이터정보과학회 2005 한국데이터정보과학회지 Vol.16 No.3

It is usually assumed that asset returns in the stock market are normally distributed. However, analyses of real data show that the distribution tends to be skewed and to have heavier tails than those of the normal distribution. In this paper, we investigate the method of estimating the value at risk(VaR) of stock returns. The VaR is computed by using the transformation and back-transformation method. The analysis of KOSPI and KOSDAQ data shows that the proposed estimation outperformed that under the normal assumption.

An Estimation of VaR in Stock Markets Using Transformations

Yeo, In-Kwon,Jeong, Choo-Mi 한국데이터정보과학회 2005 한국데이터정보과학회지 Vol.16 No.3

It is usually assumed that asset returns in the stock market are normally distributed. However, analyses of real data show that the distribution tends to be skewed and to have heavier tails than those of the normal distribution. In this paper, we investigate the method of estimating the value at risk(VaR) of stock returns. The VaR is computed by using the transformation and back-transformation method. The analysis of KOSPI and KOSDAQ data shows that the proposed estimation outperformed that under the normal assumption.

An Estimation of VaR in Stock Markets Using Transformations

In Kwon Yeo,Choo Mi Jeong 한국데이터정보과학회 2005 한국데이터정보과학회지 Vol.16 No.3

An Improved Steganography Method Based on Least-Significant-Bit Substitution and Pixel-Value Differencing

( Hsing-han Liu ),( Pin-chang Su ),( Meng-hua Hsu ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.11

This research was based on the study conducted by Khodaei et al. (2012), namely, the least-significant-bit (LSB) substitution combined with the pixel-value differencing (PVD) steganography, and presented an improved irreversible image steganography method. Such a method was developed through integrating the improved LSB substitution with the modulus function-based PVD steganography to increase steganographic capacity of the original technique while maintaining the quality of images. It partitions the cover image into non-overlapped blocks, each of which consists of 3 consecutive pixels. The 2nd pixel represents the base, in which secret data are embedded by using the 3-bit LSB substitution. Each of the other 2 pixels is paired with the base respectively for embedding secret data by using an improved modulus PVD method. The experiment results showed that the method can greatly increase steganographic capacity in comparison with other PVD-based techniques (by a maximum amount of 135%), on the premise that the quality of images is maintained. Last but not least, 2 security analyses, the pixel difference histogram (PDH) and the content-selective residual (CSR) steganalysis were performed. The results indicated that the method is capable of preventing the detection of the 2 common techniques.