• Journal of the Korean Geotechnical Society
• /
• v.24 no.12
• /
• pp.65-73
• /
• 2008

In the current practice for slope stability problem in Japan, the shear strength, $\tau$, mobilized along the failure surface is usually estimated based on an empirical approximation in which the cohesion, c, is assumed to be equal to the soil thickness above the supposed slip surface, d(m). This approximation is advantageous in that the result of stability analysis is not influenced by the designers in charge. However, since the methodology has little theoretical background, the cohesion may often be grossly overestimated, and conversely the angle of shear resistance, $\phi$, is significantly underestimated, when the soil thickness above the supposed slip surface is quite large. In this paper, a case record of natural slope failure that took place in Hyogo Prefecture in 2007, is described in detail for the case in which the shear strength along the collapsed surface was carefully examined in a series of direct shear box (DSB) tests by considering the effects of in-situ shear stress along the slip surface. It is demonstrated that the factor of safety agrees with that of in-situ conditions when the shear strength from this kind of DSB test was employed for the back-analysis of the slope failure.

• Korean Journal of Food Science and Technology
• /
• v.24 no.4
• /
• pp.393-395
• /
• 1992

The ${\alpha}-lactalbumin({\alpha}-la)$ concentration in raw and laboratory-heated milks by HPLC was 1.20 mg/ml (unheated), 1.17 mg/ml ($63^{\circ}C$, 30min), 1.13 mg/ml ($72^{\circ}C$, 15sec) and 0 mg/ml ($100^{\circ}C$, 10min), respectively. Whereas, ${\alpha}-lactalbumin$ concentration ranges of commercial milks were $1.00{\sim}1.02\;mg/ml$ (pasteurized), $0.23{\sim}0.68\;mg/ml$ (UHT-pasteurized) and $0.77{\sim}0.89\;mg/ml$ (UHT-sterilized), respectively. It was supposed that the ${\alpha}-lactalbumin$ content of sterilized milk will be lower than that of UHT milk, but the opposite occurred. This discrepancy would be caused by the different heating system in the milk plants, where indirect UHT-treatment had more heat intensity than direct UHT-processing. The HPLC determination of ${\alpha}-lactalbumin$ may be an indicator to evaluate correctly and rapidly heated milks.

• Journal of the Korean Chemical Society
• /
• v.34 no.2
• /
• pp.130-135
• /
• 1990

The title compound (C13H17NO2S) is monoclinic, space group P21/a, with a = 13.756 (3), b = 9.310(4), c = 21.305(3) $\AA$, $\beta$ = 95.0。, Z = 8, V = 2718.11 $\AA$3, Dc = 1.23$g·{\cdot}cm-3$, (Mo k$\alpha$) = 0.71069$\AA$,$\mu$ = 2.18 cm-1, F(000) = 1071.86, T = 298, R = 0.085 for 2935 unique observed reflections with I >2.0$\sigma$(I). The structure was solved by direct methods. The C-H bond lengths and the methyl groups are fixed and refined as their ideal geometry by allowing to ride on the parent atoms. Both molecules A and B have almost same structures except for two terminal ethyl groups. The ethylene-like skeleton including the nitro group in one molecule is nearly perpendicular to the plane of the methylbenzene group and two ethyl groups form a cis-type structure which has the dfferent orientations between two molecules; in the molecule A, two terminal methyl groups being the opposite directional arrangement against the plane of its skeleton, while in the B, with the same directional structure from its plane. The molecules in the crystal are packed together by non-bonded van der Waals forces.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.15 no.2
• /
• pp.271-279
• /
• 2002

This study develops the module to find the lateral stiffness influence matrix of each story and performs the displacement sensitivity analysis by virtual load method for the efficiency of optimal design using lateral stiffness influence matrix. Also, resizing technique based on the estimated lateral stiffness increment factors is developed to apply directly the results of optimal design. To this end, resizing technique is divided into the continuous and discrete section design methods. And then the relationships between section properties and section size are established. Specifically, an initial design under strength constraints is first performed, and then the lateral load resistant system is designed to control lateral displacements yet exceeding the drift criteria. Two types of 45-story three dimensional structures we presented to illustrate the features of the lateral drift control and resizing technique for tall buildings proposed in this study.

• Journal of the Korean Geotechnical Society
• /
• v.16 no.4
• /
• pp.63-70
• /
• 2000

The quantitative analyses and the mechanical interpretation of discontinuity planes are the most important factor for the study of strength and deformation properties of rock masses containing discontinuity planes. However, the relationship between the factors investigated in the field and the actual mechanical properties of discontinuity planes is not fully understood. The main purpose of this study is to investigate the effects of density, length, and spacing of joints on elastic modulus of rock masses as these values vary. A new parameter which has a direct relation with the elastic modulus of discontinuity planes is also preposed in this study. The combination of finite element methods and homogenization methods has been used for the numerical analyses of a uintcell with discontinuity planes, which is generated using random-number generation methods. The elastic modulus of the discontinuity plane is found from the numerical analyses. The final results propose not only the relation between the investigation parameters of discontinuity planes and the elastic modulus of rock masses but also a new parameter, an effect area ratio having a linear relation with the elastic modulus of rock masses.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.985-988
• /
• 2008

A linear analysis method using reduced secant stiffness was developed for inelastic earthquake design of reinforced concrete structures. In the proposed method, the beam-column element and plane element, which are the same as used in conventional elastic analysis, are used for structural modeling. Based on the structural plastic mechanism intended by engineer, the distribution of inelastic members is determined. The secant stiffness of the inelastic members is determined based on the target ductility of the structure. Inelastic strengths of the members are calculated by using linear analysis on the structure modeled with secant stiffness. Plastic rotations in the inelastic members are calculated with the nodal rotations resulting from the secant stiffness analysis. For verification, the proposed method was applied to the inelastic earthquake designs of a moment-resisting frame and a dual system of two dimensions, and also a dual system of three dimensions.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.12 no.3
• /
• pp.149-156
• /
• 2002

Europium-activated $Ga_2O_3$ phosphor powders were prepared by homogeneous precipitation method. The resulting powders were characterized by means of TG/DTA, XRD, FT-IR and SEM, Two kinds of powders formed were the crystalline GaOOH and the amorphous-like $\gamma$-$Ga_2O_3$ phases. When the urea concentration was below 0,5 M, rod-like micrometer-sized GaOOH powders were formed. They were transformed via $\alpha$-$Ga_2O_3$ to $\beta$-$Ga_2O_3$ phases under heat treatment. On the other hand, the nanometer-sized $\gamma$-$Ga_2O_3$ powders were formed with urea concentrations higher than 1.0 M, and they were directly changed into $\beta$-$Ga_2O_3$.Photoluminescence (PL) spectra were observed at room temperature, and PL intensities of nanometer-sized $Ga_2O_3$ : $Eu^{3+}$ powders around 610 nm were higher than those of micrometer-sized ones.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.10
• /
• pp.1243-1248
• /
• 2011

Internal defects are a major concern in the casting process because they have a significant influence on the strength and fatigue life of casting products. In general, they cause stress concentration and can be a starting point of cracks. Therefore, it is important to understand the effects of internal defects on mechanical properties such as fatigue life. In this study, fatigue experiments on tensile specimens with internal defects were performed. The internal defects in the casting product were scanned by an industrial CT scanner, and its shape was simplified by ellipsoidal primitives for the structural and fatigue analysis. The analysis results were compared with experimental results for casting products with internal defects. It was demonstrated that it is possible to consider internal defects of casting products in stress and fatigue analysis. The proposed method provides a tool for the prediction of the fatigue life of casting products and the investigation of the effects of internal defects on mechanical performance.

• The Journal of Engineering Geology
• /
• v.21 no.4
• /
• pp.295-304
• /
• 2011

The first step in improving our understanding of uncertainties suclt as rock mass strength parameters and deformation modulus in rock masses around high-level radioactive waste disposal repositories, for improved safety, is to study the process of crack development in intact rock. Therefore, in this study, the fracture process and crack development were examined in samples of KURT granite taken from the KAERI Underground Research Tunnel (KURT), based on acoustic emission (AE) and moment tensor analysis. The results show that crack initiation, coalescence, and unstable crack occurred at rock uniaxial compressive strengths of 0.45, 0.73, and 0.84, respectively. In addition, moment tensor analysis indicated that during the early stage of loading, tensile cracks were predominant. With increasing applied stress, the number of shear cracks gradually increased. When the applied stress exceeded the stress level required for crack damage, unstable shear cracks which directly result in failure of the rock were generated along the failure plane.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2017.05a
• /
• pp.426-426
• /
• 2017

국가간 지역간 물의 이동을 개념화하여 물 부족 현상을 정치경제학적 관점에서 접근하려는 가상수(virtual water) 연구가 국제적으로 진행되고 있다. 가상수를 양적 측면에서 산정하여 정확한 물 수지를 파악하면 수자원에 대한 국가의 계획과 전략 수립에 매우 유리한 여건이 조성된다. 우리나라의 국가계획인 수자원장기종합계획은 국가 간의 물 이동을 고려하지 않고 국내에서 발생하는 용수의 수요와 공급 측면만을 산정하고 있다. 그러나 현재에도 국내에서 소비하는 농산물과 축산물의 상당량은 수입에 의존하고 있으며, 향후 국제교역과 FTA의 확대 등으로 그 의존도는 더욱 증대될 것으로 추산된다. 따라서 국가 간 물 이동에 대한 양적 규모를 파악하여 국가전략을 수립하는 기초자료로 활용하기 위한 연구가 필요하다. 이에 본 연구에서는 산업연관분석법을 활용하여 국내 산업별(제조업, 서비스업) 가상수를 산정하여 국가 수자원계획 수립에 필요한 기초자료로서 제공하고자 한다. 산업연관분석(Inter-industry analysis)은 산업연관표를 바탕으로 산업 간의 상호 연관관계를 수량적으로 파악하는 방법이다. 이를 가상수 산정에 활용하여 직접수와 간접수를 포함한 물의 전체 사용량을 산정할 수 있다. 본 연구에서는 각 산업의 용수량을 총 생산량으로 나누어 물 강도($m^3$/원)를 계산하고, 생산유발계수와 최종수요를 곱하는 방식으로 산업별 가상수량을 산정하였다. 산업별 가상수 산정 결과는 경제총조사의 용수비와 산업연관표의 생산유발계수를 적용하였으며, 제2차 산업인 제조업 분야의 연간 가상수량은 60.4억 $m^3$, 제3차 산업인 서비스 분야의 가상수량은 연간 43.1억 $m^3$으로 분석하였다. 또한 향후 10년의 OECD 기술수준 제품군별 무역수지 전망을 고려한 결과, 기술수준 중 및 고 기술제품의 가상수 수출량이 2020년에는 2010년에 비해 약 3배 증가하는 것으로 산정하였다. 이와 같은 방법으로 산정된 산업별 가상수는 각 산업의 물 사용량을 추정하고 산업 전반의 수자원 활용도를 파악하는데 이용 가능하다. 더불어 국제 환경 및 기후변화가 반영된 가상수 시나리오 연구를 통해 장래 용수 수요변화예측 등 효과적인 물 관리 정책 수립에 기여할 수 있다.