• Proceedings of the Plant Resources Society of Korea Conference
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• 2000.10b
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• pp.16-17
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• 2000

Aralia elata is found in mountain areas all over Korean peninsula. Aralia elata is the scientific name for Japanese angelica tree. The tree belongs to the family Araliaceae, commonly known as ginseng family. Bud sprouts from apical shoot tip of the plants are rich in flavor and thus mainly used for both folk medicine and vegetable. The stalks with apical buds are gathered in the early spring and planted in sandy soil or water in the greenhouse. The sprouting buds are then collected and sold as fresh vegetable. Although the plants have been used for food, they have been cultivated in a very small scale. In spring, local farmers just go around mountain areas to search the trees and gather the stalks as much as they get and sell them to the market. No conservation efforts have been made to stop the exploitation or to save the dwindling population. We tried to provide local farmers with the plants that may be used as an alternative to stalks from wild populations. This will hel! p conserve the wild populations. However, it is hard to propagate them either by conventional cuttings or by seed germination in a short period of time. Mass propagation using tissue culture systems have shown a great promise with several woody plants. Recently we developed a mass propagation technique via somatic embryogenesis system using mature and/ or juvenile explants for Aralia elata. Several factors affecting somatic embryogenesis system including SE(somatic embryo) induction, embryogenic callus proliferation, SE germination, plant regeneration and transplanting to field will be presented. And some problems arising for the somatic embryogenesis system will be also discussed.lso discussed.

• Wind and Structures
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• v.28 no.1
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• pp.49-62
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• 2019

In this paper, an analytical analysis for the study of vibratory behavior and wave propagation of functionally graded plates (FGM) is presented based on a high order shear deformation theory. The manufacture of these plates' defects can appear in the form of porosity. This latter can question and modify the global behavior of such plates. A new shape of the distribution of porosity according to the thickness of the plate was used. The field of displacement of this theory is present of indeterminate integral variables. The modulus of elasticity and the mass density of these plates are assumed to vary according to the thickness of the plate. Equations of motion are derived by the principle of minimization of energies. Analytical solutions of free vibration and wave propagation are obtained for FGM plates simply supported by integrating the analytic dispersion relation. Illustrative examples are given also to show the effects of variation of various parameters such as(porosity parameter, material graduation, thickness-length ratio, porosity distribution) on vibration and wave propagation of FGM plates.

• Horticultural Science & Technology
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• v.28 no.5
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• pp.845-849
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• 2010

This study was conducted to compare various culture methods and evaluate economic feasibility of each method for mass propagation of new ever-bearing strawberry 'Goha'. Four different methods such as semi-solid culture, solid culture, liquid suspension culture and bioreactor culture were compared. The solid culture and bioreactor culture showed the shortest and longest root length, such as 3.6 cm and 8.3 cm, respectively. Fresh weights of plants cultured in bioreactor were 2,261 mg, which were heavier than those of cultures. Dry weights of plants cultured in bioreactor were the heavier compared to those in other cultures. The number of axillary bud developed in bioreactor was seven, but axillary bud was not developed in other cultures. Production cost through bioreactor culture was calculated to be 303 won per plant which was 542 won less than that of solid culture. As a result, we found that the bioreactor culture was the most cost effective culture method for in vitro mass propagation in new ever-bearing strawberry 'Goha'.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.5
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• pp.350-355
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• 2004

This experiment was carried out to screen the aeroponically grown host plants suitable for the mass propagation of arbuscular mycorrhizal fungi (AMF) inoculum and clarify the effect of P levels in nutrient solution on the growth of aeroponically grown sweet potato (Ipomoea batatas L.), AMF infection, and mass propagation of mycorrhizal spores, etc. Amount of biomass of host plant became higher, as the P levels in nutrient solutions increased from 5 to 20 M. AMF infection rates in mycorrhizal roots increased in higher P levels in nutrient solution, and decreased in lower parts of mycorrhizal roots by about 18.6-26.0%. About 586 mycorrhizal spores per 1 g fresh root were formed at 16 weeks after inoculation of mycorrhizal inoculum. Total of 830,479 mycorrhizal spores were propagated in each plot.

• Geomechanics and Engineering
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• v.22 no.6
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• pp.529-540
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• 2020

Water inrush is a major hazard for mining and excavation in deep coal seams or rock masses. It can be attributed to the coalescence of rock fractures in rock mass due to the interaction of fractures, hydraulic flow and stress field. One of the key technical challenges is to understand the course and mechanism of fluid flows in rock joint networks and fracture propagation and hence to take measures to prevent the formation of water inrush channels caused by possible rock fracturing. Several case observations of fluid flowing in rock joint networks and coupled fracture propagation in underground coal roadways are shown in this paper. A number of numerical simulations were done using the recently developed flow coupling function in FRACOD which simulates explicitly the fracture initiation and propagation process. The study has demonstrated that the shortest path between the inlet and outlet in joint networks will become a larger fluid flow channel and those fractures nearest to the water source and the working faces become the main channel of water inrush. The fractures deeper into the rib are mostly caused by shearing, and slipping fractures coalesce with the joint, which connects the water source and eventually forming a water inrush channel.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.1
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• pp.115-123
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• 2001

This study describes the combustion characteristics under various condition of air excess ratio and ignition timing in a 2-valve gasoline optically accessible engine with swirl control valve(SCV). It adapted three different types of SCA(open ration 72.5%, 78%, 89%) to strengthen a swirl flow. Pressure data were acquired using pressure sensor to investigate the effect of swirl flow on combustion, and from these pressure data, IMEP(indicated mean effective pressure) and MFB(mass fraction burnt)were calculated to explain burn rate and flame speed. From acquired flame images, inspected the flame propagation direction, flame area, and flame centroid, Flame propagation direction was shown different tendency between with/without SCV, and flame area with SCV was faster and larger than that of conventional engine. Finally, the representative flame image at each crank angle were acquired by PDF method to verify flame growth process. It is found that strengthened swirl flow is more beneficial for faster and stable combustion.

• Structural Engineering and Mechanics
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• v.9 no.2
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• pp.111-126
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• 2000

Truss type structures are attractive to a variety of engineering applications on earth as well as in space due to their high stiffness to mass ratios and ease of construction and fabrication. During the service life, an individual member of a truss structure may lose load carrying capacity due to many reasons, which may lead to collapse of the structure. An analytical and computational procedure has been developed to study the response of truss structures subject to member failure under static and dynamic loadings. Emphasis is given to the dynamic effects of member failure and the propagation of local damage to other parts of the structure. The methodology developed is based on nonlinear finite element analysis technique and considers elasto-plastic material nonlinearity, postbuckling of members, and large deformation geometric nonlinearity. The pseudo force approach is used to represent the member failure. Results obtained for a planar nine-bay indeterminate truss undergoing sequential member failure show that failure of one member can initiate failure of several members in the structure.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.894-899
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• 2008

Measured sensor datum from a quadruped robotics is commonly used for recognizing physical environment information which controls the posture of robotics. We can advance the ambulation with this sensed information and need to synthesize various sensors for obtaining accurate data, but most of these sensors are expensive and require excessive load for the operation. Those defects can be serious problem when it comes to the prototype's practicality and mass production, and maintenance of the system. This paper suggests virtual sensor technology for avoiding previous defects and presents ways to apply a theory to a walking robotics through virtual sensor information which is trained with several kinds of actual sensor information from the prototype system; the general algorithm is initially based on the neural network theory of back propagation. In specific, we verified a possibility of replacing the virtual sensor with the actual one through a reaction force measurement experiment.

• Plant Resources
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• v.3 no.3
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• pp.219-222
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• 2000

For the purpose of establishing an efficient propagation through airlift bioreactor system of Zingiber of officinale Rosc. Korean native Seosanjong, the effect of different factors and bioreactor on cultured plantlets were investigated. The highest number of plantlets, fresh weight per plant was obtained from explants when cultured in MS liquid medium including 0.3 mg/L NAA and 2.0 mg/L kinetin for 40 days. A 10 L bottle type bubble bioreactor, compared with 250 mL Erlenmeyer flask, was more efficient, producing 4.7 plantlets or from 1.5 to 1.6 times more than did the Erlenmeyer flask. The results demonstrate the rapid mass propagation of airlift bioreactor to produce normal ginger.

• Earthquakes and Structures
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• v.3 no.3_4
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• pp.383-411
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• 2012

The objective of the present paper is to review and implement the most recent developments in the Spectral Element Method (SEM), as well as improve aspects of its implementation in the study of wave propagation by numerical simulation in elastic unbounded domains. The classical formulation of the method is reviewed, and the construction of the mass matrix, stiffness matrix and the external force vector is expressed in terms of matrix operations that are familiar to earthquake engineers. To account for the radiation condition at the external boundaries of the domain, a new absorbing boundary condition, based on the Perfectly Matched Layer (PML) is proposed and implemented. The new formulation, referred to as the Multi-Axial Perfectly Matched Layer (M-PML), results from generalizing the classical Perfectly Matched Layer to a medium in which damping profiles are specified in more than one direction.