• Applied Microscopy
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• v.26 no.4
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• pp.457-463
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• 1996

Water storage cells (WSCs) in the leaf succulent Orostachys malacophyllus have been studied to understand their adaptive nature to its coastal habitat employing the electron microscopy. Attention has been paid to the features of vacuoles and plasmodesmata in this study, since leaf tissues in O. malacaphyllus are under continous physiological drought due to its occurrence in the shore-line environment. The WSCs occupied almost all of the leaf volume and appeared empty at low magnifications. Among the WSCs, small rudimentary vascular bundles were scattered throughout the internal volume. However, in high magnification the WSCs were vacuolate in most cases and vacuolization into a well-developed huge central vacuole was very common phenomenon. Such vacuolization has been detected within the vacuoles as well as within the cytoplasms. Well-developed plasmodesmata were often found in cells appeared to be mucilagenous. Moreover, plasmodesmata being involved in the secretion of materials or structures were even encountered. Thus, vacuolization from various sizes of vacuoles in the WSCs to have a huge central vacuole seems playing an important role in adapting the plant itself to its coastal habitat.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.132-135
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• 2003

Asymmetric rolling, in which the ratio of the rotation rates of the upper and lower rolls was 2, has been used to introduce an intense plastic shear strain for the purpose of grain refinement and developing shear deformation textures through the sheet thickness to improve the strength and plastic strain ratio of AA1050 aluminum alloy sheets. The alloy sheets were rolled at room temperature without lubrication. The textures and microstructures of the sheets were investigated by x-ray diffraction and electron back-scattered diffraction (EBSD) analyses with emphasis on effects of combinations of rot ling directions.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03a
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• pp.149-152
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• 1999

The effect of initial orientation on the microstructure and texture evolution of two ferritic stainless steels was investigated. the columnar and equiaxed crystal specimens which were prepared from continuous casting slab were hot rolled annealed cold rolled and annealed respectively. The rolling and recrystallization textures at each process stage were examined by orientation distribution function (ODF) and electron back-scattered diffraction (EBSD); The observation showed that the orientation density of the $\alpha$-fibre of hot rolled band of columnar crystal specimen was more pronounced than that of the equaxed one at the center layer. Nevertheless the cold rolled textures of Type 430 steel have demonstrated a rather similar development . Compared to Type 430 steel the development of the $\alpha$-fibre in the center layer of Type 409L steel was much more pronounced. The relation between texture evolution and ridging behaviour has been discussed.

• Transactions of Materials Processing
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• v.11 no.3
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• pp.255-261
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• 2002

The grain size of 7010 Al alloy was refined to submicrometer level by using equal channel angular pressing (ECAP) and additional warm rolling. The mechanisms of grain refinement in ECAP process were fragmentation of coarse grain to ultra fine subgrains after a few passes and continuous recrystallization of the subgrains with the increase o( passes. Because of ultrafine grain size, essentially low temperature and high strain rate superplasticity was observed after ECAP process and warm rolling to form a sheet metal. The maximum elongation of 700% was obtained for an ECA pressed specimen after IS passes without warm rolling at $450^{\circ}C$ with strain rate of 5x$10^{-3}$/sec.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.143-146
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• 2001

The evolution of dynamic recrystallization (DRX) was studied with torsion test for AISI 304 stainless steel in the temperature range of $900-1000^{\circ}C$ and strain rate range of 0.05-5/sec. The evolution of DRX was investigated with microstructural analysis and change of flow stress curve slope. The investigation of serrated grain boundaries using electron back scattered diffraction (EBSD) analysis indicated that the nucleated new DRX grain size was similar to the size of bulging part. Before the steady state, the dynamically recrystallizing grains do not remain a constant size and gradually grow to the size of fully DRX grain at steady state. The calculation of grain size was based on $X_{DRX}$ and the assumption, which the nucleated DRX grains are growing to the steady state, continuously. It was found that the calculated results agreed with the microstructure of the alloy.

• Journal of Plant Biology
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• v.32 no.3
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• pp.151-162
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• 1989

Secretory ducts in the stem of Panax ginseng seedlings are observed with light and electron microscopes to clarify development of the epithelial cells of secretory ducts. Secretory duct initial cell is developed from procambial cell which originated from initial cell is differentiated into ipithelial cell ofsecretory ducts. Intercellular space between the epithelial cells are gradually expanded and differentiated into duct lumen. Disintegrations of epithelial cells occur throughout all the stages of development. The cytoplasm of epithelial cells darken and the epithelial cell wall are lysed, preceding their disintegraton. In the epithelial cell organelles are scattered in the cytoplasm. Development of vcuoles are sparse at the early stage. Starch grains decreased gradually, while lipid droplets increased. Free ribosomes are distributed throughout the cytoplasm and secretory vesicles which originated from rough endoplasmic reticulum and Golgi complex are fused with the plasmalemma. These suggest that the cellular metabolism is active. Microtubules and plasmodesmata are typically observed in the thickened epithelial cell wall. Secretions are accumulated in duct lumen.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.222-225
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• 2006

The effect of lubrication on the development of textures and Microstructure was studied by different lubricating condition during hot rolling of AA1050 aluminum alloy. Hot rolling without lubrication led to the evolution of the pronounced through-thickness texture gradients, whereas hot rolling with lubrication gave rise to the formation of uniform rolling texture in the whole thickness layer. The variation of texture and microstructure according to hot rolling condition are investigated by X-ray diffractometer (XRD) and Electron Back-Scattered Diffraction (EBSD). The experimental results were discussed base on the finite element method (FEM) simulation. FEM calculation reveals that a larger friction between roll and sheet causes the deviated strain state from a plane strain leading to the formation of shear textures in the thickness layers close to the surface.

• The Korean Journal of Cytopathology
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• v.10 no.2
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• pp.151-155
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• 1999

A case of primary malignant fibrous histiocytoma(MFH) of the lung occurring in a 62-year-old man is presented. After preoperative bronchial blushing and washing cytologic diagnosis of poorly differentiated carcinoma, surgical resection and lymph nodes dissection were performed. Subsequent histologic examination revealed a primary MFH. The diagnosis was confirmed by electron microscopic and immunohistochemical examinations. The review of the bronchial brushing and washing cytologic features disclosed many bipolar and a few unipolar spindle tumor cells with a "comel" configuration, mainly single cells, but also forming loose clusters. The nuclei were elongated and hyperchromatic and contained one or more irregular nucleoli. Scattered bizarre, multinucleated tumor giant cells were also present.

• Applied Microscopy
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• v.17 no.1
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• pp.16-28
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• 1987

Carlaviruses were isolated from naturally infected medicinal plants, and identified by means of test plants and electron microscopy. Mottle symptoms were shown on leaves of Panax ginseng, Aralia cordata, Xanthium strumarium, Taraxacum officinale, Aconitum carmichaeli, and Bupleurum longiradiatum var. breviradiatum. Ring spot on leaves of Abutilon avicennae and ring mosaic or vein clearing on leaves of Sambucus sieboldiana were also shown. These viruses had rather narrow host ranges by mechanical inoculation. The virus particles were scattered or aggregated in cytoplasm of infected host plant leaves. The carlaviruses for which the name panax virus S (PaVS), aralia virus S (ArVS), xanthium mottle virus (XaVS), taraxacum virus S (TaVS), aconite mottle virus (AcMV), bupleurum virus S (BuVS) and abutilon ring spot virus (AbRSV) were proposed, had flexuous particles with width 13 nm and length $620{\sim}720nm$. A reported elder ring mosaic virus was isolated from leaves of Sambucus sieboldiana with ring mosaic or vein-clear symptoms.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.106-108
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• 1994

Electromigration(EM) tests were carried out on Al and Cu films in HV systems to study surface migration. The Al films were made on oxidized silicon wafers by thermal evaporation, in-situ annealed at 300$^{\circ}C$, patterned, and EM tested at 260$^{\circ}C$ and 4.5MA/$\textrm{cm}^2$. SEM observation with back scattered electron mode on the EM tested Al films disclosed that thinning took place under the native Al oxide. In the case of Cu films, tested using in-situ TEM, thinning was also observed at the early stage of void formation even though the thinned areas were much less than those of the Al films.