• 대한의생명과학회지
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• 제15권1호
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• pp.25-29
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• 2009

The changes on the regional distributions and frequencies of somatostatin-immunoreactive (IR) cells in the fundus and pylorus of the stomach of osteoporotic Sprague-Dawley rats induced by ovariectomy were studied by immunohistochemical methods. The experimental animals were divided into two groups, one for non-ovariectomized group (Sham) and the other for ovariectomized group (OVX). Samples were collected from the fundus and pylorus regions at the 10 th week after ovariectomy or sham-operation. Somatostatin-IR cells were observed in both regions of the stomach regardless of ovariectomy. Most of these IR cells in the mucosa of the fundus or pylorus were generally spherical or spindle in shape (open type cell) while cells found in the gastric gland regions were round in shape (close type cell). Significantly lower number (P<0.01) of somatostatin-IR cells were detected in OVX as compared with Sham in the fundus and pylorus. In the present study, the density of somatostatin in the stomach was markedly decreased. Therefore, these changes in density of somatostatin-IR cells detected in this study may support the speculation that the development of gastrointestinal symptoms in osteoporosis such as impairments of calcium and some lipids, frequently encountered in patients with postmenopausal osteoporosis because the changes in gastrointestinal endocrine density would reflect the change in the capacity of producing these hormones and regulating gut motility and digestion.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제29회 KOSCI SYMPOSIUM 논문집
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• pp.161-166
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• 2004

A study of argon droplet vaporization is conducted using molecular dynamics. Instead of using traditional method such as the Navier-Stokes equation. Molecular dynamics uses Lagrangian frame to describe molecular behavior in a system and uses only momentum and position data of all molecules in the system. So every property is not a hypothetical input but a statistical result calculated from the momentum and position data. This work performed a simulation of the first-order stability for phase transition of a three dementional submicron argon droplet within quiescent environment. Lennard-Jones 12-6 potential function is used as a intermolecular potential function. The molecular configuration is examined while an initially non-sperical droplet is changed into the spherical shape and droplet evaporates or condensates.

• ALGAE
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• 제19권3호
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• pp.277-282
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• 2004

Prymnesium patelliferum was collected from Hwajinpo, South Korea in November 2002. This is the first record of P. patelliferum in Korea waters. The characteristic shape of P. patelliferum was that of a rice grain. Cells were sub spherical or elongate, and sometimes slightly compressed. The motile cells of P. patelliferum (8-10 ㎛ long, 5-6 ㎛ broad) prossessed two equal or sub equal flagella(10.5-13 ㎛) and a short non-coiling haptonema (3-5 ㎛). The cell was covered by two layers of organic scales, which were important taxonomic characteristics. Internal scales were a narrow inflexed rim on the distal face, a thickening central and radial fibrillar pattern. External scales were very similar to internal scales with relatively tall upright rims. The ridges were in quadrants with 11-12 ridges per quadrant.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.254-257
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• 2003

The modified yield function of Gologanu-Leblond-Devaux in conjunction with the Barlat and Lian's yield criterion is studied to clarify the plastic deformation characteristic of voided anisotropic sheet metals. The void growth of an anisotropic sheet under biaxial tensile loading and damage effect of void growth on forming limits of sheet metals are investigated. Also, the shape parameter defining non-spherical(prolate ellipsoidal) voids with initially random orientations is introduced in M-K model. The predicted forming limits are compared with the published experimental data.

• 한국세라믹학회지
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• 제36권4호
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• pp.417-424
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• 1999

Laser lapping of diamond films is performed with focused beam of copper vapor laser. Both spherical and rod-shape laser beam are used. Diamond surface is scanned at various scan speeds(0,125, 0.5, 0.75 mm/sec) and baem shifts (5, 10, 20, 40, 100$\mu\textrm{m}$) At 0.125 mm/sec 10$\mu\textrm{m}$ scan condition the level difference of di-amond surface of about 700$\mu\textrm{m}$ over 20 mm is reduced to 200$\mu\textrm{m}$ In addition surface roughness is also im-proved from 3.53$\mu\textrm{m}$ to 2.47$\mu\textrm{m}$ at 5$\mu\textrm{m}$ beam shift. But at higher beam shift than 10$\mu\textrm{m}$ laser scan makes the surface rougher which is considered to be due to the non uniform spatial distribution of laser en-ergy. It is concluded that homogenized laser beam with high average power is needed for large area laser lapping of diamond films at appreciable rates.

• Applied Microscopy
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• 제50권
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• pp.13.1-13.7
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• 2020

We examined the morphology of fertilized egg and ultrastructures of fertilized egg envelopes of Ancistrus cirrhosus belong to Loricariidae using light and electron microscopes. The fertilized eggs formed a mass on the spawning place and were yellowish, spherical, non-transparent, demersal, adhesive, and a narrow perivitelline space. But, the adhesiveness of fertilized eggs was disappeared after spawning excluding contact parts. The micropyle with funnel shape was surrounded by 15-19 furrow lines of egg envelope in a spoke-like pattern. The outer surface of egg envelope has smooth side and inner surface of egg envelope was rough with grooves. Also, the total thickness of the fertilized egg envelope was about 32.58 ± 0.85 ㎛ (n = 20), and the fertilized egg envelope consisted of three layers, an outer adhesive electron-dense layer, a middle layer with low electron density and an inner electron-dense layer with grooves in counter structure from other most teleost. Collectively, these morphological characteristics and adhesive property of fertilized egg, and ultrastructures of micropyle, outer surface, and section of fertilized egg envelope are showed species specificity.

• Journal of Electrochemical Science and Technology
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• 제12권1호
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• pp.137-145
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• 2021

Among the non-precious metal catalysts, iron-nitrogen doped carbon (Fe-N/C) catalysts have been recognized as the most promising candidates for an alternative to Pt-based catalysts for the oxygen reduction reaction (ORR) under alkaline and acidic conditions. In this study, the nano replication method using mesoporous silica, which features tunable primary particle sizes and shape, is employed to prepare the mesoporous Fe-N/C catalysts with different shapes. Platelet SBA-15, irregular KIT-6, and spherical silica particle (SSP) were selected as a template to generate three different kinds of shapes of the mesoporous Fe-N/C catalyst. Physicochemical properties of mesoporous Fe-N/C catalysts are characterized by using small-angle X-ray diffraction, nitrogen adsorption-desorption isotherms, and scanning electron microscopy images. According to the electrochemical evaluation, there is no morphological preference of mesoporous Fe-N/C catalysts toward the ORR activity with half-cell configuration under alkaline electrolyte. By implementing X-ray photoelectron spectroscopy analysis of Fe and N atoms in the mesoporous Fe-N/C catalysts, it is possible to verify that the activity towards ORR highly depends on the portions of "Fe-N" species in the catalysts regardless of the shape of catalysts. It was suggested that active site distribution in the Fe-N/C is one important factor towards ORR activity.

• Animal Systematics, Evolution and Diversity
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• 제28권3호
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• pp.168-177
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• 2012

Two stichotrichid ciliates, collected from marine waters in Jeju Island, were identified as Afroamphisiella multinucleata Foissner et al., 2002 and Pseudokahliella marina (Foissner et al., 1982) Berger et al., 1985. They are recorded for the first time in Korea. The descriptions are based on examinations of living as well as protargol-impregnated specimens. These species are characterized as follows. Afroamphisiella multinucleata has a body size in vivo of $70-95{\times}20-35{\mu}m$; elongate rectangular in shape; contractile vacuole located slightly above mid-body. The adoral zone is bipartited into 3 distal and 13-17 proximal membranelles and occupies 28-35% of the body length. The frontal row comprises 1-4 cirri and one buccal cirrus. The amphisiellid median cirral row is composed of 14-21 cirri, 10-19 left marginal cirri, and 21-30 right marginal cirri. Cortical granules are yellowish. 11-20 globular/ellipsoidal macronuclear nodules arrange proximally along the cell margins. Pseudokahliella marina has a body size in vivo of $110-195{\times}40-110{\mu}m$ and broadly elliptical in shape. The adoral zone of the membranelles occupies 50-60% of the body length, and is composed of 41-70 membranelles. A prominent frontal scutum is present. The contractile vacuole is located below the mid-body. There are 11-13 frontoventral rows, including marginal rows. Caudal cirri and transverse cirri are absent. Three invariable non-fragmented bipolar dorsal kineties are present. The left and right marginal rows are composed of 22-35 and 28-40 cirri, respectively. Colourless cortical granules are present. 8-11 spherical/ellipsoidal macronuclear nodules are connected with each other by thread-like tructures, forming an inverted C-shape.

• 한국수산과학회지
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• 제53권4호
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• pp.583-587
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• 2020

Imitation fish roe (IFR) based on calcium alginate hydrogels (CAG) can be heat treated for sterilization and salted to prolong the shelf life. However, these processes change the physical properties of IFR, and it is necessary to minimize these changes. In this study, we investigated the effects of xanthan gum (XG) treatment on the quality and stability of IFR. Both non-XG and XG-treated IFRs were treated with boiling water (95℃), sodium chloride (0.5-2.0%, w/v), and autoclaving. The non-XG treated IFR shrunk slightly after the boiling water and autoclaving processes. By comparison, shrinkage of the XG-treated IFR after autoclaving was significantly reduced. The sphericity of the non-XG treated IFR was reduced by the boiling water, sodium chloride, and autoclaving treatment. However, the sphericity of the XG-treated IFR was maintained by 90% or more, preserving the IFR shape at a level visually recognized as spherical. In addition, unlike the non-XG treated IFR, the XG-treated IFR showed high rupture strength even after the salt and heat treatments. Our findings provide useful information for the industrialization of IFR based on CAG with heat and salt treatments.

• 산업기술연구
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• 제20권A호
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• pp.29-36
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• 2000

The shape of the polymers in the mixed alkoxide solutions of Si(OC2H5)4 and Zr(n-OC3H7)4 with various water contents (1, 2, 4, and 8 in molar ratio to alkoxide, r) and catalysts was examined by rheological measurements, and its relation with fiber drawing behavior of the solutions was described. It was found that fibers could be drawn in the viscosity range 1~100 P from the acid-catalyzed solutions with lower water contents of the molar ratio H2O/alkoxide, $r{\leq}2$. On the other hand, no fiber could be drawn from the acid-catalyzed solutions including a large amount of water($r{\geq}4$) and the base-catalyzed solutions. The relation between the intrinsic viscosity [${\eta}$] and number average molecular weight ${\bar{M}}n$, namely $[{\eta}]=K{\bar{M}}n{\alpha}$, has shown that the acid-catalyzed spinnable solution (r = 1 and 2) had linear polymers where the exponent a's were about 0.56 and 0.81, whereas non-spinnable solutions (r = 4 and 8) had three dimensional network polymers or spherical particles where the exponent a's were 0.41-0.51 and 0.35.