• Applied Microscopy
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• v.8 no.1
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• pp.49-52
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• 1978

Mask cells are distributed in the animal tissue, The bat subject has not been studied with the electron microscope, The material was fixed in 2.5% phosphate buffered glutaraldehyde for 24 hours at $4^{\circ}C$ and then post-fixed in phosphate buffered 1% osmium tetroxide for 2 hours at $4^{\circ}C$ and then the cleared tissues were embedded in Epon. The mast cell has numerous cytoplasmic processes projecting into the surrounding connective tissue. In general, the cytoplasmic granules showed ovoid, round, lunal or irregular shape, most of them were fine particulate substructure in texture. Especially, the granules was enclosed by the lamella structure.

• Journal of the Korean Wood Science and Technology
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• v.35 no.2
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• pp.9-15
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• 2007

A comparative study of the structure and organization of the primary and secondary walls in different types of tropical plant waste fibers was carried out using transmission electron microscopy (TEM). The thickness of each layer was also measured using Image Analyzer. TEM micrographs haveconfirmed that cell wall structure of all six types of tropical plant waste fibers (empty fruit bunch, oil palm frond, oil palm trunk, coir, banana stem and pineapple leaf) has the same ultrastructure with wood fibre. The fibers consisted of middle lamella, primary and thick secondary wall with different thickness for different types of fibers. The secondary wall was differentiated into a $S_1$ layer, a unique multi-lamellae $S_2$ layer, and $S_3$ layer.

• Architectural research
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• v.10 no.1
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• pp.25-32
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• 2008

Stability is a very important part which we must consider in structural design. In this paper, we take advantage of finite element method to study parametrical instability of lattice dome structures, which is subjected to harmonically pulsating load. We consider elastic stiffness and geometrical stiffness simultaneously during the calculation of stiffness matrix, and adopt consistent mass matrix to make the solution more correct. In order to obtain instability regions, we represent displacements and accelerations in dynamic equation by trigonometric series expansions, and then obtain Hill's infinite determinants. After first order approximation, we can get first and second order dynamic instability regions eventually. Finally, we take 24-bar star dome and 90-bar lamella dome as examples to investigate dynamic instability phenomena.

• Journal of Powder Materials
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• v.9 no.3
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• pp.148-152
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• 2002

The microstructures and indentation fracture of pressureless-sintered $DyNbO_4$ crystalline were investigated as a basic study for the application of weak phase of fibrous monolithic composites. They were comprised with many lamella twins as well as micro-cracks at the grain boundaries. The hardness at room temperature was remarkably low value(575 Hv) due to the low relative density and existence of microcracks at grain boundaries. The main fracture mode was a typical intergranular fracture, and showed remarkable micro-cracking effect. The heavy plastic deformation was observed around the site of indentation. In addition, the $DyNbO_4$ was expected to apply as a weak phase in the fibrous monolithic composites because of the low hardness and easily plastic deformation that could be led the preferable pulled-out and microcracking toughening under the failure.

• Environmental Analysis Health and Toxicology
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• v.11 no.3_4
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• pp.45-51
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• 1996

Histopathological changes of gills and caudal fins isolated from fishes, Cyprinus carpio, Carassius auratus, and Hernibarbus labeo, which were killed by oxygen deficiency or toxic chemicals, were studied. The toxic chemicals were HCl, NaOH, chloroform, benzene, heavy metals(Cu, Cr, Zn, Pb, Hg), and o-dichlorobenzene. The exposure level was enough to kill the fishes within 30 minutes. Oxygen deficient water was prepared by aeration of nitrogen gas and the oxygen concentration was less than l ppm. Cryocutting was used for the rapid preparation of tissue slides and the tissues were stained by hematoxylin/eosin. In the fishes killed by hazardous chemicals, congestion and/or hyperplasia of secondary lamella and erosion of fin were found as the major histopathological changes. Whereas, these characteristics were not observed in gills or caudal fins of fishes killed by oxygen deficiency. These different bioindications appeared in the fishes killed by toxic substances or natural causes, can be used for the rapid identification of the causes of fish kills.

• Korean Journal of Veterinary Research
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• v.35 no.4
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• pp.809-814
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• 1995

The acute and subacute toxicity of fumomsin $B_1$ was evaluted in fingerlings of common carp, Cyprinus carpio. Dipping of fish for acute toxicity was performed for a period of 48 hours, and the $TLm_{48h}$ value(median tolerance limit) was more than 1000 ppm in common carp. Severe damages were observed in various organs and among them, clubbing of gill lamella, lytic degeneration and vacuolation of liver cells, and epithelial edema of renal tubules were relatively prominent. The most significant changes were hyperbasophilic foci of liver cells in subacute toxicity test and these can imply the possibility of hepatocarcinogenecity of fumonisin $B_1$.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.11a
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• pp.205-214
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• 1999

In order to investigate the influencing factors of flotation fractionation. flotations were performed at varied conditions. The selectivity of fines fractionation is mainly affected by long fibers flocculating degree and if it were not for sufficient flocculation of long fibers, increase of long fibers loss could not be avoided. The amount of flotation reject totally depends on the stability of forth floated on the stock surface. only the small size fines stabilize the froth as they hinder the drainage of liquid lamella in flotation-froth. Two important factors of flotation conditions are improving the flocculation of long fibers and increasing the amount of flotation reject. Changing a flotation flux or an air-mixing ratio with aims of increasing the flocculation of fibers and reject ratios is in conflict. In order to satisfy the both conditions for reducing long fiber loss and for increasing flotation reject a new fractionation promoter is urgently required.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.3
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• pp.461-470
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• 1998

The effects of addition of water extract of pine needle(WEPN) on texture and cell wall polysac-charides content of kimchi during fermentation at 1$0^{\circ}C$ were investigated. Textural properties of hardness, gumminess and cohesiveness of kimchi were higher for WEPN-added kimchi than for the control during the entire fermentation periods, while its adhesiveness was lower. Alcohol insoluble substance, among cell wall polysaccharide fractions of kimchi was higher in WEPN-added kimchi than in the control but water soluble materals was high in control during fermentation periods. The separation phenomenon of middle lamella of control kimchi tissue was observed at 14th days of fermentation but WEPN-added kimchi showed at 21th days fermentation. The vasular of kimchi tissue was more destroyed in control than in WEPN-added kimchi.

• Journal of Korea Foundry Society
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• v.7 no.3
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• pp.192-198
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• 1987

Commercial semicontinuous cast ingots of aluminum alloys often exhibit large grains composed of parallel arrays of continuous lamellae. Each lamella consists of a central {111} coherent twin boundary and wavy solidification boundary. This microstructure is referred to as a twin columnar growth(TCG) structure. The factors influencing the formation of a TCG structure include a unidirectional thermal gradient and the critical range of the alloying element content. The higher the thermal gradient is, the shorter the twin plane spacings are. The composition profile for an untwinned dendrite shows maximums at the positions of the interdendritic channels and the minimum appears at the center of the dendrite. While for twinned dendrite, it has wavy apperance. This profile has two local minimums instead of one shown in the untwinned.

• Journal of fish pathology
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• v.18 no.2
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• pp.125-131
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• 2005

Amoebic gill disease of flounder, Paralichthys olivaceus was diagnosed at commerical culture facility in South Korea. The amoeba was identified as a species of the genus Neoparamoeba based on the morpholgical characteristics of trophozoites. Transmisson electron microscopy revealed the presence of a symbiotic organism, parasome in the cytoplasm and dense glycocalyx on the surface of the trophozoites. They lacked the boat-shaped microscales on the surface and contained numerous vacuoles and channels, mitochondria in the cytoplasm. Colonization of amoebae on gill tissue elicited extensive fusion and hyperplasia of gill lamella.