• Journal of the Korean Magnetics Society
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• v.11 no.6
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• pp.245-249
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• 2001

Natural convection of a magnetic fluid is different from that of Newtonian fluids because magnetic body force exists in an addition to gravity and buoyancy. In this paper, natural convection of a magnetic fluids (W-40) in annular pipes was studied by experimentally. Inside wall was kept at a constant temperature (25 $^{\circ}C$), and outside wall was also held at a constant but lower temperature (20 $^{\circ}C$). The magnetic fields of various magnitude were applied up. This study has resulted in the following fact that the natural convection of a magnetic fluids was controlled by the direction and intensity of the magnetic fields.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.5
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• pp.752-757
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• 1999

Studies were made of digestion of timothy (Pheleum pretense) hay, tall fescue (Festuca elatior) hay, and rice (Oryza sativa) straw in pure cultures of rumen anaerobic fungus, Neocallimastix frontails MCH3. The fungus was inoculated on ground forages (1%, w/v) in an anaerobic medium and incubated at $39^{\circ}C$. Incubation was continued for 24, 48, 72 and 96 h. The losses of dry matter, xylose and glucose of forage during incubation were determined at the end of these incubation periods. Xylose and glucose were considered to be released from xylan and cellulose, respectively. The digested xylan to digested cellulose (X/C) ratios of the substrate were calculated. Xylanase and carboxymethyl cellulose (CMCase) of culture supernatant and residual substrate was measured at the same time. The X/C ratios in the cultures on timothy hay and rice straw were greater than 0.5 in the first 24-h incubation period. The values were smaller than 0.3 in tall fesque. The ratio of xylanase activity to that of CMCase in the first 24-h incubation period correlated well with the traits in X/C ratio. However xylanase activity was still superior to CMCase in the following incubation period (48 to 96 h), although the glucose (designated as cellulose) was more intensively digested than xylose (designated as xylan). The production of these polysaccharidases appeared to correlate with substrate cell-wall sugar composition, xylose to glucose ratios, at the beginning of fast growing period.

• Korean Journal of Materials Research
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• v.19 no.9
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• pp.473-480
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• 2009

In order to provide the mechanism of nozzle clogging, recovered nozzles for high strength steel grade were examined carefully after continuous casting. The thickness of clogged material in SEN is increased in the following order: from the bottom to the top of the nozzle, upper part of slag line, and the pouring hole. Nozzle clogging material begins to form due the adhesion of metal to nozzle wall, the decarburization, and reduction of oxide in the refractory by Al and Ti in the melt. The reduction of oxide in the refractory by Al and Ti improves the wettability of the melt on the refractory and forms a thin Al-Ti-O layer. Metal containing micro alumina inclusions is solidified on the Al-Ti-O layer, and the solid layer grows due to the heat evolution through the nozzle wall. Thermodynamic calculation has been made for the related reactions. The effect of superheat to the nozzle clogging is discussed on ultra low carbon steel and low carbon steel.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.9
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• pp.843-852
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• 2000

The flow characteristics and the heat transfer rate on a surface by interaction of a pair of vortices were studied experimentally. The test facility consisted of a boundary-layer wind tunnel with a vortex introduced into the flow by half-delta winglet protruding from the surface. In order to control the strength of the longitudinal vortices, the angles of attack of the vortex generators were varied from $\pm20\;degree\;to\;\pm45$ degree, but spacings between the vortex generators were fixed to 4 cm. The 3-dimensional mean velocity measurements were made using a five-hole pressure probe. Heat transfer measurements were made using the thermochromatic liquid to provide the local distribution of the heat transfer coefficient. By using the method mentioned above, the following conclusions were obtained from the present experiment. The boundary layer was thinned in the regions where the secondary flow was directed toward the wall and thickened where it was directed away from the wall. The peak augmentation of the local heat transfer coefficient occurred in the downwash region near the point of minimum boundary-layer thickness.

• International Journal of Fluid Machinery and Systems
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• v.4 no.3
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• pp.349-359
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• 2011

An unsteady numerical analysis has been carried out to study the strong impeller volute interaction of a centrifugal pump with six backward swept blades shrouded impeller. The numerical analysis is done by solving the three-dimensional Reynolds Averaged Navier-Stokes codes with standard k-${\varepsilon}$ two-equations turbulence model and wall regions are modeled with a scalable log-law wall function. The flow within the impeller passage is very smooth and following the curvature of the blade in stream-wise direction. However, the analysis shows that there is a recirculation zone near the leading edge even at design point. When the flow is discharged into volute casing circumferentially from the impeller outlet, the high velocity flow is severely distorted and formed a spiraling vortex flow within the volute casing. A spatial and temporal wake flow core development is captured dynamically and shows how the wake core diffuses. Near volute tongue region, the impeller/volute tongue strong interaction is observed based on the periodically fluctuating pressure at outlet. The results of existing analysis also proved that the pressure fluctuation periodically is due to the position of impeller blade relative to tongue.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.2
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• pp.329-340
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• 1997

A passive control of interaction of condensation shock wave / boundary layer for reducing the strength of condensation shock was conducted experimentally in a 2.5 * 8 cm$^{2}$ indraft type supersonic wind tunnel. The effects of following factors on passive control were investigated: 1) the thickness of porous wall, 2) the diameter of porous hole, and 3) the orientation of porous hole. On the other hand, the location of nonequilibrium condensation region and condensation shock wave was controlled by regulation of the stagnation conditions. Surface static pressure measurements as well as Schlieren observations of the flow field were obtained, and their effects were compared with the results the cases of without passive control. It was found that thinner porous wall, smaller porous hole and FFH orientation for the same cavity size and porosity of 12% are more favourable than the cases of its opposite.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.9 no.2
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• pp.160-163
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• 1998

The glottis consists of two parts : The intermembranous portion or the anterior glottis, and the posterior glottis. The posterior glottis has been described by various inappropriate terms such as posterior commissure and interarytenoid region. The structure surrounding the posterior glottis consists of three portions ; The cartilaginous portion of the vocal fold, the lateral wall of the posterior glottis, and the posterior wall of the glottis. The posterior glottis may be a very rare site for primary squamous cell carcinoma of the larynx because of its embriologic and histologic differences from the anterior glottis. Recently we have experienced a case of a 81-year-old woman who had been presented with throat discomfort and voice change for 10months. She had the smoking history of 40 pack-year. The physical examination revealed poorly demarcated, papillary, whitish-pink colored mass on the posterior glottis. The vocal cord mobility was not affected. Biopsy under the suspension larygoscope showed moderately differentiated squamous cell carcinoma. No regional and distant metastasis was found. She was irradiated with 7000cGy over 7 weeks at a daily dose of 200cGy. No evidence of recurrence was found by the fifteenth month following radiation therapy. We report this case with a review of literature.

• Food Science and Biotechnology
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• v.15 no.6
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• pp.877-883
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• 2006

The immunostimulatory activities of Lactobacillus plantarum, the major microorganism in kimchi fermentations were investigated. Five strains of L. plantarum exhibited weak immunopotentiating activity, but L. plantarum PS-21 showed as strong a mitogenic activity as Bifidobacterium adolescentis M101-4, a known positive strain. It is of interest that, L. plantarum PS-21 stimulated proliferation of Peyer's patch cells, one of the most important tissues in the gut-associated lymphoreticular system. Cell' wall fractions from L. plantarum PS-21 also showed strong mitogenic activity compared with the soluble cytoplasmic fraction. A peptidoglycan fraction (PG) extracted from the cell wall of L. plantarum PS-21 was identified as an active mitogenic component when used in murine lymph node and spleen cell test systems. PG showed dose-dependent mitogenic activity and significantly enhanced antibody production in lymph node cells when studied in vitro. The lysosomal enzyme activity of murine peritoneal macrophages was increased when analyzed following injection of PG to the host animal. Furthermore, PG enhanced the production of cytokines such ($TNF-{\alpha}$ and IL-6) in the in vitro culture of RAW 264.7 macrophage cells.

• Korean Journal of Veterinary Pathology
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• v.1 no.1
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• pp.72-76
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• 1997

Histological investigation of the number of follicles following gonadotropin treatments for superovulation was carried out in mature Sprague-Dwaley(SD) rats. Routinely serial sections of paraffin-embedded ovaries were stained with hematoxylin-eosin and evaluated with light microscope. During the study unusual cases of microscopic alterations were observed in the medulla of ovaries in two rats. Case one: An ovum and its follicular fluid outflowed in medulla of ovary. The follicular fluid was densly proteinuous. Corona raiata consisted of 2-6 layers thick cells in the periphery of the ovum. While the cortical side of the follicular wall was intact with normal granulosa cell layer the meullary side of it was ruptured. Case two: A large cyst was present in medulla of ovary hilus. The cyst occupied the entire medulla displacing the ovarian archetecture and enclosed by connective tissue and smooth muscle wall.

• Journal of Chest Surgery
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• v.7 no.1
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• pp.93-100
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• 1974

This is a case report of successful surgical correction of coarctation of the aorta associated with the patent ductus arteriosus and the persistent left superior vena cava. The patient was a 15 year old girl and congenital heart anomaly was suspected at the sixth month after birth. Afterward there has been no embarrassing symptoms until the day of operation except slight dyspnea on exertion, The diagnosis of coarctation of the aorta and the patent ductus arteriesus detected by physical signs and X-ray studies including aortography. In the first place, coarctation of the aorta was corrected with following procedure: partial resections of the aortic wall just above and below the coarctating line of the aorta and removal of diaphragmatic structure of coarctation performed by. cross clamping aorta above and below coarctation, and then the defect of the aortic wall was closed by lateral aortorrhapic suture with atraumatic needle 3-0 silk continuously [Fig. 6]. In the second place, the patent ductus arteriosus was closed with double ligation method. The persistent left superior vena cava left as it has been, because there has been no evidence of hemodynamic abnormal shunt. After operation, excellent result was obtained; blood pressure in the upper and lower extremities was normalized and subjective complains of hypertension in the upper extremity was disappeared.