• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.1
• /
• pp.21-26
• /
• 1993

A study on the fatigue fracture at electro discharge machined(E.D.M) surface has been made with special emphases on the microstructure variation and the residual stress distribution at the E.D.H heat affected zone. Results obtained are summarized as follows. (1) E.D.M brings about a variation of microstructure in heat affected zone, structures of molten, quenching, tempering are formed in order of formation from E.D.M surface. (2) Residual stress generated by E.D.M reduces the fatigue strength of the material through the influencing fatigue crack initiation and growth. (3) Magnitude of the residual stress existed in a microscopic area is approximately estimated by a COD measurement method which was originally suggested by authors.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.485.1-485.1
• /
• 2014

In this research, we report the synthesis of three-dimensional (3D) hierarchical porous graphene aerogels (hpGAs) for application to electrochemical energy storage. For electrochemical systems, the specific capacitance is a key parameter to evaluate the characteristics of electrode materials. By taking full advantage of large surface area, 3D hpGAs would achieve the larger specific capacitance over rGO film and GAs. Microscopic structures and topologies of hpGAs were investigated using field emission scanning electron microscopy and transmission electron microscopy. X-ray photoelectron spectroscopy was used to determine the chemical compositions of rGO film, GAs, and hpGAs. Raman spectra were recorded from 100 to 2500 cm-1 at room temperature using a Raman spectroscopy equipped with a ${\times}100$ objective was used. The specific area and pore distribution of GAs and hpGAs were obtained using a Brunauer-Emmett-Teller apparatus.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.13 no.1
• /
• pp.52-59
• /
• 2000

In order to develop the transparent anti-static film with higher than 80% transparency to visible light, organic conductive compounds, N-methyl phenazinium 7,7,8,8-tetracyanoquinonedimethane (TCNQ) com-plex salts was synthesized and bar-coated on the polythylene terephthalate (PET) film using polymer binders. The best surface properties were obtained when acrylic binder was used. A single layer of TCNQ made of a acrylic binder showed a surface resistance of 10\ulcorner $\Omega$/ , a conductivity of 10\ulcorner S/cm, and a transparency of 75%. An optical microscopic examination revealed that the binder was first solidi-fied on the surface of PET film over which the needle-shaped TCNQ crystals were grown. An acrylic polyol coating over the TCNQ layer improved the transparency to 87%, becuase the acrylic polyol covers the surface of TCNQ crystals to reduce the surface roughness. This conductive material has thermal stability at room temperature and 4$0^{\circ}C$ over 4,000 h.

• Korean Journal of Veterinary Research
• /
• v.37 no.3
• /
• pp.471-477
• /
• 1997

The morphological and immunohistochemical characteristics of the adrenal gland of the lion(Panthera leo) have been studied. In the light microscopic level, the adrenal gland was surrounded by thick capsules arid weak development of the zona glomerulosa was detected. Some medullary tissues were directly connected with capsules, however the adrenal gland in the lion 'demonstrated somewhat pseudolobulated appearance. Weakly or strongly stained chromogranin-immunoreactive cells were detected in medullary regions of the adrenal gland of the lion by immunohistochemistry, and weakly stained chromogranin-immunoreactive cells were detected more frequent than strongly stained ones.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2000.10a
• /
• pp.337-342
• /
• 2000

Experimental investigations were carried out to find the characteristics of grinding of ceramics. Grinding mechanisms of ceramics were inspected through the microscopic examination. It has been found that the specific grinding energy of ceramics is relatively low as compared to that of steels. The specific grinding energy affects the surface roughness and the residual stress of ground surface. The experimental results indicate that the rougher surface finish and higher compressive residual stress are obtained at lower specific grinding energy. The surface roughness and the residual stress of the ground surface have significant effects on the strength of ground piece of ceramics.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2008.04a
• /
• pp.200-203
• /
• 2008

Water mist fire suppression system utilizes the fire suppression features such as cooling of fire source, dilution of ambient oxygen, and shielding of radiation heat with the evaporation of microscopic water droplets. The momentum of water mist is relatively low and the infiltration of water mist to the fire source is not effective. In addition to lower penetration force, the evaporated water vapor is liable to decline to limited portion of fire source due to its light weight and sparse density. On the other hand, the cycling water mist system is expected to improve the penetration force of water mist as well as the dilution coverage capability with the stratified spray characteristics. At this paper we present the analyzed fire suppression capability of intermittent water spray pattern by use of FDS which is computational fire dynamics fire model. We expect this analysis shall be supportive to the development of the prototype of water mist nozzle.

• Journal of the Korean Society of Visualization
• /
• v.16 no.1
• /
• pp.61-69
• /
• 2018

Ion exchange membrane can transfer only cation or anion in electrically conductive fluids. Recent studies have revealed that such selective ion transport can initiate electroconvective instability, resulting vortical fluid motions on the membrane. This so-called electroconvective vortex (a.k.a. electroconvection (EC)) has been in the spotlight for enhancing an ion flux in electrochemical systems. However, EC under shear flow has not been investigated yet, although most related systems operate under pressure-driven flows. In this study, we present the direct visualization platform of EC under shear flow. On the transparent silicone rubber, microscale channels were fabricated between ion exchange membranes, while allowing microscopic visualization of fluid flow and ion concentration changes on the membranes. By using this platform, not only we visualize the existence of EC under shear flow, its unique characteristics are also identified: i) unidirectional vortex pattern, ii) its advection along the shear flow, and iii) shear-sheltering of EC vortices.

• Journal of Applied Biological Chemistry
• /
• v.43 no.2
• /
• pp.74-78
• /
• 2000

A strain that produces a high level of carboxymethyl cellulase was isolated from rotten leaves. The isolated strain was revealed to be gram-negative, oxidase-positive, and catalase-negative. From the electron microscopic features, it was identified as a rod-shaped bacterium with peritrichous flagella and did not form spores. Morphological and biochemical characteristics of the strain were found to be similar to the Pseudomonas species. However, carbon utilization test showed different results. Based on the results, this new strain was identified as Pseudomonas sp. CMC-50. CMCase produced by this strain showed a strong activity in neutral and weak acidic conditions and maximum activity at $50^{\circ}C$.

• The Korean Journal of Cytopathology
• /
• v.2 no.2
• /
• pp.134-141
• /
• 1991

Localized or solitary fibrous tumor (SFT) of the pleura has been classified as a type of mesothelioma, arising from the submesothelial connective tissue cells. The preoperative diagnosis of the tumor at the cytologic or histologic level is very important for the proper handling of the lesion. This preoperative diagnosis is now possible by means of the advance in the transthoracic fine needle aspiration biopsy (FNA) techniques and in the very experience of the cytopathologists. We describe FNA cytologic feature of two cases of SFT arising from the pleura. Cytologic, histologic, immunohistochemical, and electron microscopic characteristics of pleural SFT are discussed. The tumor cells of SFT are spindle or oval in shape with a variable amount of cytoplasm. They are arranged in irregular trabeculae intimately associated with capillaries. A unique cytologic feature observed in this tumor is that thick, eosinophilic, amorphous collagen bundles are scattered between tumor cells.

• Korean Journal of Clinical Laboratory Science
• /
• v.36 no.1
• /
• pp.7-12
• /
• 2004

Trichophyton(T.) tonsurans has been identified for the first time in Korea in 1995 and has been increasing in number of reported in wrestlers, in judo players, and in korean - style wrestlers. Author tried mycological studies with T. tonsurans is isolated in Daegu Korea. The results are as follows: All 16 strains of T. tonsurans tested for nutritional requirement, showed strongly stimulated growth by thiamine, mild to moderate growth on casamino acid agar, poor growth on ammonium nitrates base agar. All 16 strains of T. tonsurans tested showed positive results for hair perforation and urease test. Gross findings of T. tonsurans showed that fine granular surface with light yellow hue or white color and mahogany brown color on the reverse side. Microscopic findings showed that septated hyphae, chlamydoconidia and microcondia. Microconidia were characteristic in their arrangerment and shape : round or oval shaped microconidia laterally to hyphae, some were match - head like terminal swelling.