• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.435-441
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• 2017

Studies on self-healing have currently been diversified and the methods to evaluate the studies have become more diversified as well. Among them, the back-scattered electron (BSE) image acquired through the scanning electron microscope (SEM) is attempted as the means to evaluate the self-healing effect on cracks. In order evaluate by the BSE image, sophisticated pre-processing of specimen is critical and this injected inside the particle, pore and artificial crack of the hardener to stabilize the structure of the newly generated self-healing product and it enables to endure the stress on polishing without deformation. The impregnated specimen smoothen the surface to obtain the BSE image of high resolution that polishing is made for diamond suspension for wet polishing after dry polishing. As a result of evaluating the self-healing product on the impregnated and polished self-healing specimen, the generated product is formed from the surface of the artificial crack and the self-healing substances are confirmed as $Ca(OH)_2$ and C-S-H.

• The Korean Journal of Malacology
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• v.25 no.2
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• pp.145-151
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• 2009

The ultrastructural changes in germ cells during oogenesis of the melania snail, Semisulcospira libertina libertina have been investigated by light and electron microscopy. The ovary is located on the surface of the hepatopancreas in the spiral posterior region. The ovary exhibited greenish color in the gonadal mature season. The ovary was composed of a number of oogenic follicles. Oogenesis was divided into five stages with histological features: (1) oogonia, (2) previtellogenic, (3) initial vitellogenic, (4) active vitellogenic, and (5) mature stages. Oogonia were oval in shape, $4-6\;{\mu}m$ in diameter, and had a large nucleus. Previtellogenic oocytes were about $20\;{\mu}m$ in diameter and the cytoplasm reacted with hematoxylin in H-E satin. Initial vitellogenic stage, oocytes were $60-80\;{\mu}m$ in diameter, and small yolk granules of low electron density are scattered in the cytoplasm. Oocytes in the initial vitellogenic stage were connected with ovarian follicle by egg stalk. Active vitellogenic oocyte were $100-120\;{\mu}m$ in diameter. Electron density, size and quantity of yolk granules that are distributed in the cytoplasm have increased from the previous stage. Result of TEM observations, the oocyte contains well-developed Golgi complex, endoplasmic reticula and tubular mitochondria in the cytoplasm. Cytoplasm of mature oocyte was filled with proteinaceous yolk globules of high electron density. In this stage, the length of microvilli in the egg envelope was approximately $1.1\;{\mu}m$.

• The Korean Journal of Cytopathology
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• v.1 no.1
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• pp.111-120
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• 1990

Small cell neuroendocrine carcinoma of the uterine cervix is a distinct subtype of cervical cancer that appears analogous to oat cell carcinoma and carcinoid tumors of the lung. It has been assumed to be derived from the neural crest via argyrophilic cells in the normal endocervix. We have recently encountered a case of small cell neuroendocrine carcinoma of the uterine cervix coexisting with adenocarcinoma which was argyrophil negative. A 66-year-old multiparous woman was admitted because of vaginal bleeding for 2 months. Cervicovaginal smear revealed several scattered clusters and sheets of monotonous small cells with some peripheral palisading in the background of hemorrhage and necrosis. Radical hysterectomy specimen revealed an ulcerofungating tumor on endocervical canal which was composed of two components. Major component of the tumor was made up of monomorphic population of small oval-shaped tumor cells arranged in sheets and partly in acinar structures or trabecular fashion. Other component was adenocarcinoma, endocervical well-differentiated type. Argyrophilia was present on the Grimelius stain and immunohistochemical studies revealed diffuse positivity to neuron-specific enolase and carcinoembryonic antigen. Electron microscopic examination showed clusters of small round to oval cells, which had a few well-formed desmosomes and several membrane-bound, dense-core neurosectetory granules.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3191-3195
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• 2012

New silver nanoparticle (AgNP)-loaded amino acid based hydrogels were synthesized successfully from poly (vinyl alcohol) (PVA) and poly(acryl amide-co-acryloyl phenyl alanine) (PAA) by redox polymerization. The formation of AgNP in hydrogels was confirmed by using a UV-Vis spectrophotometer and XRD. The structure and morphology of silver nanocomposite hydrogels were studied by using a scanning electron microscopy (SEM), which demonstrated scattered nanoparticles, ca. 10-20 nm. Thermogravimetric analysis revealed large differences of weight loss (i.e., 48%) between the prestine hydrogel and silver nanocomposite. The antibacterial studies of AgNP-loaded PAA (Ag-PAA) hydrogels was evaluated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. These Ag-PAA hydrogels showed significant activities against all the test bacteria. Newly developed hydrogels could be used for medical applications, such as artificial burn dressings.

• Journal of the Korean Society for Heat Treatment
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• v.31 no.6
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• pp.307-314
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• 2018

Simple tensile tests and microstructural investigations have been performed on extrudates of high strength aluminum alloys such as 7075, 7021 and 7xxx(Sc) to understand correlation between extruding conditions and extruded properties. Tensile specimens which were taken from different locations at the same cross section of an extrudate were tested at room temperature and with a strain rate of $8.9{\times}10^{-5}/s$. The microstructures according to the locations at the cross section have been observed using optical microscopy and electron back-scattered diffraction (EBSD) mapping to characterize the effect on stress-strain curve. The results could be classified in three types independent of alloying contents and extusion methods. The fine differences in the stress-strain curves were resulted from inhomogenity in the microstructures according to locations of an extrudate which were performed through instantaneous extruding conditions such as temperature, strain rate and strain.

• Journal of The Korean Astronomical Society
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• v.51 no.4
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• pp.111-117
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• 2018

A numerical method is proposed to calculate the response of detectors measuring particle energies from incident isotropic fluxes of electrons and positive ions. The isotropic flux is generated by injecting particles moving radially inward on a hypothetical, spherical surface encompassing the detectors. A geometric projection of the field-of-view from the detectors onto the spherical surface allows for the identification of initial positions and momenta corresponding to the clear field-of-view of the detectors. The contamination of detector responses by particles penetrating through, or scattering off, the structure is also similarly identified by tracing the initial positions and momenta of the detected particles. The relative contribution from the contaminating particles is calculated using GEANT4 to obtain the geometric factor of the instrument as a function of the energy. This calculation clearly shows that the geometric factor is a strong function of incident particle energies. The current investigation provides a simple and decisive method to analyze the instrument geometric factor, which is a complicated function of contributions from the anticipated field-of-view particles, together with penetrating or scattered particles.

• Applied Microscopy
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• v.28 no.3
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• pp.379-390
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• 1998

Dermal wound healing responses in the skin of the toad, Bombina orientalis, were examined using transmission electron microscopy. At 12 hours after wounding, debridement and collagenolysis occurred in damaged dermis. Histocyte has a large nucleus and long cytoplasm process. Phagocytic vesicle and lysosome were observed in the cytoplasm. Damaged blood cells were transformed spindle to irregular shape. Autolysis was observed in their cytoplasm. Histocytes are found in poly-band. The irregularly shaped nucleus is located peripheral region in cytoplasm. At 2 days after wounding, partial aggregation of blood cells is observed. Phagocytic, activity is observed in histocyte and collagenolytic collagen fibers are scattered. Fibroblast is observed in the dermis at 3 days after wounding. Clusters of ribosomes and some short cisternae of rough-surfaced endoplasmic reticulum are found in the cytoplasm. In histocyte at 7 days post wounding, various size granules composed of moderately dense material are found the cytoplasm. In this period histocyte is round to rod in profile, with slender processes projecting from the surface. At 7 day after injury, it was observed that formation of connective tissue fibers and amorphous ground substance in regenerating skin.

• Korean Journal of Veterinary Research
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• v.37 no.4
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• pp.817-823
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• 1997

Suckling piglets and weaned pigs showed anorexia, dehydration, severe abdominal breathing, emaciation and paresis from Oct. 1993. to Nov. 1993. Five 2-week-old piglets were submitted for diagnosis in Kangwon National University. At necropsy, the pin-point well demarcated yellowish white foci were scattered on the surface of the lung, heart, liver, spleen and kidney. Histologically, multifocal areas of necrosis with mononuclear cells infiltration were found in the lung, heart, liver, lymph node, spleen, kidney and small intestine. These lesions tended to be associated with blood vessels. Variable round to ovoid tachyzoites were located at the periphery of the lesions. The organisms were demonstrated as Toxoplasma gondii by immunohistochemical staining method. Ultrastructurally, this parasite was surrounded with parasitophorous vacuole in alveolar macrophage. The parasite was crescent-shaped and $6{\sim}8{\times}1{\sim}2{\mu}m$ in size. It was enclosed by an thick outer membrane and an underlying thin inner membrane. Several club-shaped paired organelles and conoids lay in the cytoplasm at the anterior. Numerous round body and one to several mitochondria were presented in the cytoplasm. Based on the gross findings, histopathology, immunohistochemical and electron microscopic findings, this case was diagnosed as toxoplasmosis in piglets.

• Mycobiology
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• v.31 no.1
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• pp.1-8
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• 2003

Detailed structures of ectomycorrhizae formed in Pinus roots were observed with various microscopes: light, fluorescence, and scanning electron microscopes. The mantles and Hartig nets commonly found in the structure of ectomycorrhiza were newly observed according to developmental stage by various staining. The mycelia were observed to be composed of coiled types on the surface of epidermal root during early stage and fused to form mantles of smooth fungal layers, loosing mycelia with some viscous liquid secreted. The ectomycorrhizal hyphae in anatomical roots penetrated the cortical layer and formed obviously mantle and Hartig net. The round spots of ectomycorrhizal mycelia were observed morphological distribution from the cortical layer to vascular bundle of stele in the ectomycorrhizal roots of Pinus species and especially scattered at the area of meristem at the root tip as longitudinal sections. Those mycelia penetrated seemed to move into other roots by means of vascular bundle of ectomycorrhizal roots and newly form ectomycorrhizal roots of dichotomous branches.

• Analytical Science and Technology
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• v.14 no.1
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• pp.50-58
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• 2001

The effect of cryogenic heavy rolling method on grain refinement has been studied and compared with those obtained by previous methods of cryogenic rolling and heavy rolling developed separately. Both grain structure and grain size were analyzed using electron back scattered diffraction (EBSD), which can distinguish grains each other by means of crystallographic misorientations between them. The cryogenic rolling and heavy rolling exhibit reduction in grain size of 39% and 87%, respectively, and the cryogenic heavy rolling shows reduced grain size similar to that observed in the heavy rolling. The heavy rolling was proved more effective in grain size refinement than the cryogenic rolling.