• The Journal of Engineering Geology
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• v.5 no.2
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• pp.201-213
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• 1995

Understanding of the fracture processes in rock mass for hydrogeology necessitates such information as fracture mechanics including genesis, propagation, termination, and the relation of fracture distribution to geologic structures and fracture modelling, etc. A current status of information on fracture for groundwater flow in rock mass, however, is very paucity except on a few special fields throughout the world. The desired and reasonable approach method in the evaluation on the groundwater flow in fractured rock mass must be based on the thorough understanding of fracture processes and a simplified model representing fracture properties which would be met to natural conditions for the interpretation and prediction.

• Korean Journal of Plant Resources
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• v.19 no.2
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• pp.252-258
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• 2006

The most effective conditions of In vitro culture and ex vitro sporophyte formation from prothallus were studied for mass propagation of Dyropteris varia. The most effective medium of prothallus proliferation was Murashige and Skoog's basal medium supplemented with 10:50mM of $NH_4^+:NO_3^-$ and 2% sucrose. The optimum pH level was 5.8 and prothallus growth was promoted on medium containing $0.6{\sim}0.8%$ agar. Almost of the tested growth regulators (NAA, IAA, 2,4-D, BAP, kinetin and 2ip) were inhibitory in prothallus proliferation as the concentration of growth regulators became higher. The highest number of sporophytes was obtained by transplanting prothallus on compost only than on any other soil compositions. Sporophyte formation was promoted remarkably by soaking prothallus with $100{\mu}M\;GA_3$ for 3 hours.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.3
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• pp.269-276
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• 2001

Ultrasonic testing of composite materials is much more difficult than that of isotropic materials, because of the beam skew phenomenon caused by their elastic anisotropy. An established analytical method exists for elastic wave propagation in anisotropic media as a result of previous research efforts. Yet, due to the complexity of the analytical method, solution of real problems must resort to the numerical method. In this work, analytical solutions have first been obtained for the wavefield due to a point source in a unidirectional fiber-reinforced composite, which may be modeled as transversely isotropic. Then, the corresponding numerical solutions have been obtained using the mass-spring lattice model(MSLM). The two solutions have agreed well with each other. Other problems such as reflection from free boundaries and scattering from cracks have also been solved numerically, and the results have been investigated from the viewpoint of wave mechanics. The numerical model whose validity has been confirmed by this work will be of great use in simulating ultrasonic testing of composite materials.

• Korean Journal of Plant Tissue Culture
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• v.27 no.6
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• pp.479-484
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• 2000

This study was conducted to examine the effects of explant sources and plant growth regulators on mass propagation of Cyclamen persicum. Tuber, cotyledon, and petiole tissues were cultured on MS medium supplemented with different concentrations and combinations of auxins and cytokinins. Shoots were not induced from calli on cotyledon and petiole explants cultured on MS medium containing various concentrations of 2,4-D or NAA. However, multiple shoots were formed directly from tuber explants cultured on the medium containing 0.5 and 1.0 mg/L 2,4-D or NAA. In MS medium with cytokinin alone, TDZ was more effective in shoot formation than BA or kinetin in all explants. The combinations of NAA and BA was found to be most effective in shoot formation from tuber, cotyledon and petiole explants. Especially, shoots were formed from all the tuber explants on the medium containing 0.5 mg/L of NAA and BA. Hormonal effects on root formation were examined by subculturing single shoots on MS medium containing NAA or IBA. The medium with 0.5 mg/L IBA was most effective in root induction and subsequent plantlet regeneration.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.2
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• pp.21-33
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• 1992

Under the intense-impulsive loading, structures are subjected to the wide range of pressures at an instantaneous time. The constitutive laws capable to describe the material behavior under the extreme pressure as well as the low pressure are necessary for the analysis of the structural behavior under the intense -impulsive loadings. In this study, two plastic models, the pressure independent Von-Mises model and the pressure dependent Drucker-Prager model, are employed for the wave propagation analysis. Governing equations of this study are conservation equations of momentum and mass in Lagrangian coordinate system which is fixed to the material. Due to the shock-front which violates the continuity assumptions inherent in the differential equations numerical artificial viscosity is used to spread the shock front over several computational zones. These equations are solved by Finite Difference Method with discretized time and space coordinates. The associate normality flow rule as a plastic theory is implemented to find the plastic strains.

• Journal of Plant Biotechnology
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• v.30 no.4
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• pp.359-363
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• 2003

Mass propagation of tulip tree (Liriodendron tulipifera L) via somatic embryogenesis was successfully achieved with immature samaras collected from adult trees. Embryogenic tissues were induced by culturing them samaras on 1/2 LM medium (Litvay's) containing 2,4-D and BA. Somatic embryos developed from the embryogenic tissues and germinated to normal plants (emblings) upon transfer onto the same medium containing either AgNO$_3$ or activated charcoal. So far, several factors appeared to influence both the induction of embryogenic tissues and germination of the embryos into plants. These include the collection time of samaras for the induction of embryogenic tissue, sucrose level in the culture medium, the level of both AgNO$_3$ and activated charcoal, and plating density of somatic embryos on germination medium for maturation and germination of somatic embryos into plantlets.

• Fire Science and Engineering
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• v.13 no.3
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• pp.3-17
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• 1999

Smoldering is a non-flaming combustion mode, characterized by thermal degradation and c charring of the virgin material, evolution of smoke and emission of visible glow. A big fire may @ occur even in a confined environment having a limited amount of oxygen, due to smoldering c combustion through a porous solid material. This paper presents a theoretical analysis on the effect of smoldering combustion on fire occurrence based on a report about fire investigation of a real f fire accident. It is assumed that the propagation of the smolder wave is one-dimensional, d downward, opposing an upward forced flow and steady in a frame of reference moving with the s smolder wave. Smoldering combustion is modeled by a one-step reaction mechanism, without c considering pyrolysis. It is found that dominant parameters controlling smoldering combustion i include mass flux of oxidizer entering the reaction zone and void fraction of solid fuel. It is also found that the mechanism of transition to flaming is critically influenced by these two parameters.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.70.2-70.2
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• 2014

We developed a three-dimensional (3D) magnetohydrodynamic (MHD) simulation code to reproduce the structure of a solar wind and the propagation of a coronal mass ejection (CME) through it. This code is constructed by a finite volume method based on a total variation diminishing (TVD) scheme using an unstructured grid system (Tanaka 1994). The grid system can avoid the singularity arising in the spherical coordinate system. In this study, we made an improvement of the code focused on the propagation of a CME through a solar wind, which extends a previous work done by Nakamizo et al. (2009). We first reconstructed a solar wind in a steady state from physical values obtained at 50 solar radii away from the Sun via an MHD tomography applied to interplanetary scintillation (IPS) data (Hayashi et al. 2003). We selected CR2057 and inserted a spheromak-type CME (Kataoka et al. 2009) into a reconstructed solar wind. As a result, we found that our simulation well captures the velocity, temperature and density profiles of an observed solar wind. Furthermore, we successfully reproduce the general characteristics of an interplanetary coronal mass ejection (ICME) obtained by the Helios 1/2 spacecraft (R. J. FORSYTH et al. 2006).

• Korean Journal of Plant Resources
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• v.15 no.3
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• pp.279-284
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• 2002

To establish the mass propagation method of Typha orientatis Presl, several factors influencing seed germination were investigated. The best seed germination of T. orientalis was achieved under the light and 25~3$0^{\circ}C$ temperature. GA$_3$ tended to enhance seed germination, and 500 mg.L$^{-1}$ GA$_3$ showed 90.7% germination, which was 1.2 times of control. Compared to control, BA treatment prohibit seed germination. Especially, seeds were not germinated under 500 mg.L$^{-1}$ BA treatment. In case of KNO$_3$ and Ca(NO$_3$)$_2$ treatment, the germination rate was decreased by all concentrations, except 100 mM Ca(NO$_3$)$_2$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.6
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• pp.678-686
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• 1997

This experiment was carried out to develop the mass propagation system for producing plug plantlets using stem cuttings of virus-tree microtubers in potato. Cocopeat, vermiculite, perlite and peatmoss were combined and used as plug nursery media to find out the best combination suitable for the growth of seedlings derived from microtubers. Seedling growth was favored in high temperature (above 2$0^{\circ}C$) and a long-day photoperiod(above 16 hours) condition, while stolons and microtubers formed in outdoor condition. Shoot and root multiplication was not affected by NAA 10mg /1 or IAA 10mg /1 treatment. At the early growth stage of plug plantlets, the number of leaves and roots and the length of root increased significantly when nodes from the upper (near to apex) part of shoots rather than from basal part were taken. But after transplanting, these differences among these characters were not observed. At ninety days after transplanting the plug plantlets in spring time, plant was around 70 to 80cm in height, and the number of stolons and tubers were ten and seven, respectively.