• Journal of the Korean Society for Heat Treatment
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• v.16 no.3
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• pp.127-133
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• 2003

The effect of chemical composition on the microstructural change and tensile property in TRIP-assisted steels with different chemical composition was investigated by using SEM, TEM, XRD and UTM. As a result of microscopic observation, the morphology of retained austenite could be identified as two types; a granular type in a steel containing higher Si and a film type in a steel having higher C. For the case of higher C-containing steel with a tensile strength of 860 MPa and a total elongation of 38%, film-typed retained austenite could be observed between lath bainitic ferrite. Actually, metastable retained austenite was a requisite for the good formability, which means that chemical composition plays a significant role in the microstructure and tensile property of TRIP-assisted steels. With respect to tensile property, the steels containing suitable Si and Mn, respectively, showed a typical TRIP effect in stress-strain curve, while a steel containing higher Mn content exhibited the similar behavior shown in dual phase steel.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1441-1455
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• 1993

Under unlubricated condition, the friction and wear tests of silicon nitride and zirconia manufactured by HIP were carried out at room temperature. The wear resistance of silicon nitride was superior to that of zirconia under low load, whereas the wear resistance of zirconia was superior to that of silicon nitride under high load. Wear model of ceramic was suggested by the microscopic SEM observation of worn surfaces and debris. Theoretical analysis and discussions based on linear fracture mechanics were made out about this ceramic wear model. From the theoretical analysis, a new nondimensional parameter, Scf, was introduced to estimate wear rate of ceramics. This new nondimentional parameter consists of contact pressure, surface defect of contact material, frictional coefficient and fracture toughness.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.22 no.2
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• pp.159-161
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• 2011

Malignant fibrous histiocytoma is one of the rare types of larynx tumor. The most common sites of the tumor are limbs, trunk, and retroperitoneal space, but tumor localization within head and neck are very rare. It is built of histiocytes, fibroblasts and multinuclear giant cells. A diagnosis of the tumor includes microscopic and immunohistologic examination with identification of specific tissue markers and intermediate filaments of proteins. This disease has been treated by several methods combining radical surgery, radiotherapy, and chemotherapy, but the prognosis is poor. We present 74-year-old Asian man with dysphonia for 2 years. The tumor of the larynx was examined on laryngoscopy. The radical surgery rendered the final pathological diagnosis, confirmed histologically and immunohistochemically as malignant fibrous histiocytoma. This tumor was treated with laser cordectomy followed by radiotherapy. 3.5 year's observation of the patient didn't either show any signs of recurrence or dysphonia.

• Korean journal of food and cookery science
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• v.15 no.6
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• pp.639-644
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• 1999

The objective of this study was to compare the quality characteristics of cultured and red sea bream. The color of dorsal muscle was different between wild and cultured red sea bream. Lipid content of the dorsal muscle was higher in cultured fish than in wild one. The contents of moisture and crude protein in cultured fish muscle were almost same as those of wild one. Sensory evaluation of raw fish meat showed that cultured fish had lower preference in appearance, taste and texture than wild one. Especially the texture of cultured raw fish meat had lower preference than wild meat. For cooked fish meat, cultured fish were harder and less juicy than wild fish. These textural differences between wild and cultured meats were confirmed by objective evaluation including the measurements of hardness, springiness, and cohesiveness. Light microscopic observation showed that cultured red sea bream had more lipid in the surface layer near epidermis than wild one. Also more lipid droplet between muscle fibers were observed in cultured red sea bream by SEM.

• Archives of Pharmacal Research
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• v.22 no.1
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• pp.35-43
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• 1999

Overstimulation of both kainate (KA) and N-methyl-D-aspartate (NMDA) receptors has been reported to induce excitatoxicity which can be characterized by neuronal damage and formation of reactive oxygen free radicals. Neuroprotective effect of melatonin against KA-induced excitotoxicity have been documented in vitro and in vivo. It is, however, not clear whether melationin is also neuroportective against excitotoxicity mediated by NMDA receptors. In the present work, we tested the in vivo protective effects of striatally infused melatonin against the oxidative stress and neuronal damage induced by the injection of KA and NMDA receptors into the rat striatum. Melatonin implants consisting of 22-gauge stainless-steel cannule with melatonin fused inside the tip were placed bilaterally in the rat brain one week prior to intrastriatal injection of glutamate receptor subtype agonists. Melatonin showed protective effects against the elevation of lipid peroxidation induced by either KA or NMDA and recovered Cu, Zn-superoxide dismutase activities reduced by both KA and NMDA into the control level. Melatonin also clearly blocked both KA- and NMDA-receptor mediated neuronal damage assessed by the determination of choline acetyltransferase activity in striatal monogenages and by microscopic observation of rat brain section stained with cresyl violet. The protective effects of melatonin are comparable to those of DNQX and MK801 which are the KA- and NMDA-receptor antagonist, respectively. It is suggested that melatonin could protect against striatal oxidative damages mediated by glutamate receptors, both non-NMDA and NMDA receptors.

• Natural Product Sciences
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• v.9 no.2
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• pp.97-101
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• 2003

This study was undertaken to evaluate the antinociceptive and antiinflammatory effects of the heartwood extract of Rhus verniciflua (Anacardiaceae) and the two major components, sulfuretin and fustin. The MeOH extract, its EtOAc-soluble portion and sulfuretin showed significant antinociceptive activity in writhing and hot plate test assays and antiinflammaory effects in carrageenan-induced hind paw edema in rats. In particular, treatment of sulfuretin with 10 mg/kg dose (i.p.) reduced writhing frequency by 48.0% (p<0.01) compared to that of a control group. Further, the treatment of sulfuretin (5, 10 mg/kg, i.p.) for 7 days prevented the carrageenan-induced hind paw edema significantly (p<0.01). The antiinflammatory effect of sulfuretin was also confirmed by microscopic observation of mast cell numbers in muscle. In addition, sulfuretin suppressed the cyclooxygenase- 2 (COX-2) activity $(IC_{50}\;=\;28.7\;{\mu}M)$ in lipopolysaccharide-activated macrophage cells. This result indicates that the inhibitory effect of sulfuretin on COX-2 may be one of the antinociceptive/antiinflammatory mechanism.

• Korean Journal of Veterinary Research
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• v.34 no.2
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• pp.339-347
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• 1994

This study was carried out to investigate the pathological changes with paraquat(1.1'-dimethyl-4.4'-dipyrildiylium dichloride) administered by intraperitoneally, orally, skin applied in mice, rats and rabbits. Results were obtained as follows; In 2 days after paraquat administration clinical signs anorexia, depression, tachypnea, and tachycardia, respiratory failure, coma and death were observed in mice, rats and rabbits. Compared toxicity of paraquat with mouse were observed toward to paraquat that resistance was strong than rats and rabbits. Also, mortality of skin application were found the low than intraperitoneal and high than oral administration. In the case of gross observation were appear lips moisture in orally administered rats and rabbits by skin application. Lung of all laboratory animals were observed congestion and haemorrhage, swelling or atrophy. In the case of microscopic findings were severe congestion and haemorrhage, interstitial pneumonia of lung. Congestion and haemorrhage of liver, congestion and haemorrhage, renal tubule epithelium necrosis of kidney were observed in mice, rats and rabbits. Skin application group of mice, rats and rabbits showed infiltration of inflammatory cells and folliculitis of epidermis and dermis. Also, in oral administration group showed congestion and haemorrhage, tachment, necrosis of alimentary tract mucosa.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.3
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• pp.106-113
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• 2007

The effect of chemical composition on the microstructural change and tensile property in TRIP-assisted steels with different chemical composition was investigated by using SEM, TEM, XRD and UTM. As a result of microscopic observation, the morphology of retained austenite could be identified as two types : a granular type in a steel containing higher sillicon and a film type in a steel having higher carbon. For the case of higher carbon-containing steel with a tensile strength of 860 MPa and a total elongation of 38%, film-typed retained austenite could be observed between lath bainitic ferrite. Actually, metastable retained austenite was a requisite for the good formability, which means that chemical composition plays a significant role in the microstructure and tensile property of TRIP-assisted steels. With respect to tensile property, the steels containing suitable silicon and manganese, respectively, showed a typical TRIP effect in stress-strain curve, while a steel containing higher manganese content exhibited the assimilar behavior shown in dual phase steel.

• Applied Microscopy
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• v.21 no.1
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• pp.86-107
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• 1991

An experimental study was performed to observe the early effects of monocrotaline on pulmonary vascular system by means of light microscopy and scanning electron microscopy, attempting to expore the mechanism behind the process of pulmonary hypertension. Experimental animal(Sprague-Dawley male rats ; 150-200g B. W.) were intra-peritoneal administered with 100mg/kg B. W. monocrotaline. Authors observed light microscopically various gradational increase of wall thickness in pulmonary muscular and non-muscular arteries in duration from 2 weeks to 5 weeks after monocrotaline administration and the changes were more sever in the latter than the former. The scanning electron microscopy shows severe and diffuse endothelical cell swelling, microvilli and microbleb formation since 1 hour after monocrotaline administration and during the course, after 5 hours the severity of endothelial cell damage was prominent with presence of fibrin, webs, platelet thrombi and white cell adherence. It was concluded that the monocrotaline primarily induced severe and diffuse endothelial cell damage of pulmonary arteries and laterly added the participation of platelets, which attributed to the pathogenesis of monocrotaline induced pulmonary vascular lesions in relation to pulmonary hypertension.

• Journal of the Korean Society for Heat Treatment
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• v.24 no.5
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• pp.262-270
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• 2011

Carbide precipitation and dissolution behavior at various temperatures during heat treatment has been studied in STD11 cold working die steel through confocal scanning laser microscopy; dilatometry; and X-ray diffraction analysis. The equilibrium phase diagram and phase fractions with temperature were calculated using a FactSage program. Confocal laser microscopic observation revealed that ${\alpha}$ to ${\gamma}$ transformation temperature is near $800^{\circ}C$; M7C3 carbides melt at $1245^{\circ}C$; and the melting temperature of STD11 is near $1370^{\circ}C$. XRD results indicated that the M23C6 carbides dissolve in the matrix if austenitized at over $1030^{\circ}C$; while the M7C3 carbides remain up to $1200^{\circ}C$ although their amount decreases. The calculated equilibrium phase diagram showed good agreement with experimental results on carbide dissolution and phase transformation temperatures.