• Geomechanics and Engineering
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• 제32권5호
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• pp.475-482
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• 2023

This paper studies the effect of the relaxation time on a two-dimensional thermoelastic medium which has a doubly porous structure in the presence of diffusion and gravity. The normal mode analysis is used to obtain the analytic expressions of the physical quantities, which we take the solution form in the exponential image. We have discussed a homogeneous thermoelastic half-space with double porosity with the effect of diffusion and gravity. The equations of generalized thermoelastic material with double porosity structure with one relaxation time have been developed. Moreover, the expressions of many physical quantities are explained. The general solutions, under specific boundary conditions of the problem, were found in some detail. In addition, numerical results are computed.

• 대한수학회보
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• 제60권5호
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• pp.1365-1374
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• 2023

Let F be a periodic singular fiber of genus g with dual fiber F^*, and let T (resp. T^*) be the set of the components of F (resp. F^*) by removing one component with multiplicity one. We give a formula to compute the determinant | det T | of the intersect form of T. As a consequence, we prove that | det T | = | det T^*|. As an application, we compute the Mordell-Weil group of a fibration f : S → ℙ¹ of genus 2 with two singular fibers.

• 대한기계학회논문집A
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• 제26권8호
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• pp.1698-1708
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• 2002

The main topic covered in this paper is that of the impact process, that is, where two bodies come into contact and rebound or stick together. This paper presents how to determine the rebound velocities of a microparticle that approaches a surface with arbitrary initial velocities and relate the impact process to the physical properties of the materials and to the adhesion force. Actual adhesion forces demonstrate a significant amount of energy dissipation in the form of hysteresis, and act generally in a normal to the contact surfaces. Microparticles must also contend with forces tangent to the contact surfaces, namely Coulomb dry friction. The developed model has an algebraic form based on the principle of impulse and momentum and hypothesis of energy dissipation. Finally, several analyses are carried out in order to estimate impact parameters and the developed analytical model is validated using experimental results.

• Journal of the Korean Wood Science and Technology
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• 제44권6호
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• pp.903-912
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• 2016

Morphological and anatomical evaluation of grafted P. merkusii have been undertaken to obtain the information about compatible and incompatible symptoms of 18 years old grafts based on morphological observation and microscopic analysis. Samples of compatible and incompatible grafts were obtained from previous research conducted by the Silviculture Departement Team in 1994. Result showed that compatible grafts have normal stem form and secondary growth (diameter growth), but some abnormality symptoms like undulated pattern of annual growth rings, phloem thickening and abnormality resin ducts in inner and middle parts of the union area occurred. Incompatible ones showed abnormality of the stem form, cortex-bark necrosis and swelling in the union area. Microscopic observation showed abnormality of all parts of the union, undulated pattern of annual growth rings, phloem thickening, abnormal resin ducts, low numbers and discontinuity of vascular elements in the union area.

• 미생물과산업
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• 제20권1호
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• pp.50-52
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• 1994

Coccidioides immitis의 mycelial phase와 tissue phase에 있어서 미세구조를 다음과 같은 결론을 얻었다. 1. mycelial phase의 세포구조에서는 정상적인 균이 보유하고 있는 내용물질을 관찰할 수 있었으며 이는 다른 eucaryotic cell의 구조와 같았다. 2. tissue phase에서는 mycelial phase의 세포의 크기보다 비교적 크기가 컸으며 mycelial phase에서 보다 많은 종의 vacuole이 관찰되었다. 3. Tissue phase에서는 fibril form의 내연층을 볼 수 있었다.

• 대한수학회보
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• 제54권6호
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• pp.2001-2011
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• 2017

In 1997, H. Li [12] proposed a conjecture: if $M^n(n{\geqslant}3)$ is a complete spacelike hypersurface in de Sitter space $S^{n+1}_1(1)$ with constant normalized scalar curvature R satisfying $\frac{n-2}{n}{\leqslant}R{\leqslant}1$, then is $M^n$ totally umbilical? Recently, F. E. C. Camargo et al. ([5]) partially proved the conjecture. In this paper, from a different viewpoint, we study closed convex spacelike hypersurface $M^n$ in locally symmetric Lorentz space $L^{n+1}_1$ and also prove that $M^n$ is totally umbilical if the square of length of second fundamental form of the closed convex spacelike hypersurface $M^n$ is constant, i.e., Theorem 1. On the other hand, we obtain that if the sectional curvature of the closed convex spacelike hypersurface $M^n$ in locally symmetric Lorentz space $L^{n+1}_1$ satisfies $K(M^n)$ > 0, then $M^n$ is totally umbilical, i.e., Theorem 2.

• Steel and Composite Structures
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• 제24권3호
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• pp.369-382
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• 2017

This study investigates the reliability of the performance levels of moment resisting steel frames subjected to lateral loads such as wind and earthquake. The reliability assessment has been performed with respect to three performance levels: serviceability, damageability, and ultimate limit states. A four-story moment resisting frame is used as a typical example. In the reliability assessment the uncertainties in the loadings and in the capacity of the frame have been considered. The wind and earthquake loads are assumed to have lognormal distribution, and the frame resistance is assumed to have a normal distribution. In order to obtain an appropriate limit state function a linear relation between the loading and the deflection is formed. For the reliability analysis an algorithm has been developed for determination of limit state functions and iterations of the first order reliability method (FORM) procedure. By the method presented herein the multivariable analysis of a complicated reliability problem is reduced to an S-R problem. The procedure for iterations has been tested by a known problem for the purpose of avoiding convergence problems. The reliability indices for many cases have been obtained and also the effects of the coefficient of variation of load and resistance have been investigated.

• 대한수학회보
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• 제39권4호
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• pp.671-680
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• 2002

In this article, we show that if a semi-Riemannian space form carries a conformal vector field V of which the tangential part $V^T$ on a connected hypersurface $M^N$ ecomes a conformal vector field and the normal part $V^N on $M^N$ does not vanish identically, then $M^N$ is totally umbilic. Furthermore, we give a complete description of conformal vector fields on semi-Riemannian space forms.

• 한국잠사곤충학회지
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• 제6권
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• pp.9-17
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• 1966

The ratio of form and character in the text generation of silkworms which were double copulated between home race copulation and hetero race copulation in crossing with two males of different races for female(double crossing) are different according to the copulating time, copulating order and sperm activities. But the general tendencies are as follows; 1. During two hour's double copulation, sufficiently ejaculating time, the fertilization percentage of hetero lace copulation are higher than that of homo race, but in case of double copulation with plain and normal marked silkworms showed opposite results. The fertilization percentage of homo race copulation are equal or higher compare with that of hetero race copulation. 2. The form and character of the next generation were largely effected by copulating order, so the primary copulating moths are more effected in the next generation than the secondary moths. 3. The active sperms were more fertilized than non-active sperms in the double copulation.

• Journal of Plant Biotechnology
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• 제30권2호
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• pp.195-199
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• 2003

Extracts of Escherichia coli as a elicit were treated to suspension cultures of Streptanthus tostus in order to observe the effect on the pholem development. By the elicit treatment, cell wall, sieve endoplasmic reticulum (SER) and p-protein were normally synthesized, but the structure of amyloplast was changed from a round form to irregular and swollen unhalthy form with a tiny starch granular. Oil drops were new synthesized and accumulated in a large oleoplast and proteins were also accumulated in a single membrane. The concentration of sucrose in the phloem, which was induced during the elicit treatment, was higher than normally developed phloem cells. These results suggest that phloem cells might be changed in the normal cycles of metabolism of lipids, carbohydrates and proteins to overcome during the eilicit stress.