• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.4
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• pp.847-864
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• 1988

The main purpose of this study is to investigate the local velocity acceleration in a boundary layer diffusion flame over a flat plate. In order to know the effect of separation on the local velocity acceleration, two typical cases, flows with and without separation, are considered. For these cases, flow visualization using paraffine smoke tracers has been made. Mean velocity and r.m.s. value of fluctuating velocity are measured by using a laser Doppler velocimeter. In addition, measurements of time-mean concentration and time-mean temperature have been made. Time-mean density profiles have been obtained from the data of concentration and temperature. The obtained results are summarized as follows : (1) In the case without separation, the local velocity acceleration is clearly observed near the visible flame zone for all flow conditions. On the while, in the case with serration, the local velocity acceleration is observed only at low free stream velocity and high fuel injection velocity. As increasing the free stream velocity or decreasing the fuel injection velocity, it is not distinctly observed in the mean velocity profile. (2) The r.m.s. value of fluctuating velocity is significantly decreased by combustion in the case with separation. But in the case without separation, the r.m.s. value is increased near the visible flame zone in comparison with cold flow. In both cases, the peak value of r.m.s. appeared just at the visible flame zone, where the mean velocity gradient is not too high.

• Applied Chemistry for Engineering
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• v.5 no.1
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• pp.127-138
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• 1994

In the process of pervaporation separation for aqueous ethanol solution through cellulose tai-acetate(CTA) membrane, the modelling on the solution-diffusion permeation mechanism was built up on the basis of sorption and permeation experimental results. Also its function type and parameter were examined. The composition of sorption equilibrium in three component system(Ethanol/Water/CTA) were compared with the calculated value by Flory-Huggins' equation using the pure component sorption data. In order to apply the thermodynamic equilibrium relationship between the membrane free composition in the membrane and the equilibrium composition in the liquid phase, the apparent activity this system, however, the results were not satisfied. Diffusion equations were expressed with the concentration gradient considering permeate alone, and a concentration-dependent diffusion coefficient which includes a parameter was used. And this model was fitted with the measured permeation rates. If the permeation rate and the amount of sorption of one component were much larger than those of the other, the bulk flow term could not be negligible. The flux and selectivity were increased with increasing temperature, and with decreasing downstream pressure.

• Korean Journal of Food Science and Technology
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• v.27 no.2
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• pp.176-180
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• 1995

Direct contact heat exchange (DCHE) method has been employed to investigate the separation of ethanol from dilute aqueous solutions. Bubbles at high temperature were dispersed into a continuous liquid phase, generating temperature gradient in air-liquid interface, which causes heat and mass transfer accordingly. The experiments were performed in the ranges of jet regime air flow. The air-water stripping coefficient increased $5{\sim}10,\;and\;1{\sim}1.5$ times as temperature and air flow rate increased, respectively. The recovery ratio based on the initial ethanol concentration reached into 80% at the air flow rate of 84.88 m/min. The initial ethanol concentration showed little effect on the stripping coefficient and the recovery ratio.

• Applied Biological Chemistry
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• v.19 no.3
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• pp.121-129
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• 1976

A high concentration of myo-Inositol in rat's milk was observed (61-91mg. of myo-Inositol per 100g of milk) by gas-liquid chromatographic method, using a 3% SE-52 column. Feeding experiments showed that approximately 85% of myo-Inositol in milk was from dietary origin: the rest was considered to be synthesized by 1L-myo-Inositol-1-phosphate lyase. Results suggested that the biosynthesis was not sufficiently high to permit the maintenance of its myo-Inositol level in milk. However, study $using(^{14}C)-glucose$ injection into lactating female rats confirmed biosynthesis of myo-Inositol from glucose in mammary gland. This biosynthesis reached a maximum within an hour after $(^{14}C)-glucose$ injection intraperitoneally as lactose biosynthesis did. Study using $(^3H)-myo-Inositol$ confirmed that most of the myo-Inositol in milk was transported from blood plasma myo-Inositol against a concentration gradient. About four hours after the beginning of the injection of $(^{14}C)-glucose$, the specific radioactivity of myo-Inositol in milk was 8% of that of glucose in the blood. When $(^3H)-myo-Inositol$ was injected, the specific radioactivity of myo-Inositol in milk was about 26% of that of blood six hours after injection.

• Korean Journal of Crystallography
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• v.8 no.1
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• pp.15-19
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• 1997

Single crystals of Co-doped quartz (blue quartz) were grown hydrothermally from the $Na_2CO_3$ solution. The size of as-grown crystal was $100{\times}50{\times}35mm^3$ and the growth rate was 0.55 mm/day under the growth condition of $5wt.\%\;Na_2CO_3$ mineralizer, growth temperature of $343^{\circ}C$ and temperature gradient of $22^{\circ}C$. Visible spectrum showed a typical absorption feature of the synthetic blue quartz near 545, 570 and 643 nm. The concentration of color of the as-grown blue quartz related not to the concentration of cobalt in raw material but to the growth temperature.

• Nuclear Engineering and Technology
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• v.42 no.1
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• pp.79-88
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• 2010

Spent $UO_2$ nuclear fuel discharged from a nuclear power plant (NPP) contains fission products, U, Pu, and other actinides. Due to neutron capture by $^{238}U$ in the rim region and a temperature gradient between the center and the rim of a fuel pellet, a considerable increase in the concentration of fission products, Pu, and other actinides are expected in the pellet periphery of high burnup fuel. The characterization of the radial profiles of the various isotopic concentrations is our main concern. For an analysis, spent nuclear fuels originating from the Yeonggwang-2 pressurized water reactor (PWR) were chosen as the test specimens. In this work, the distributions of some actinide isotopes were measured from center to rim of the spent fuel specimens by a radiation shielded laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) system. Sampling was performed along the diameter of the specimen by reducing the sampling intervals from 500 ${\mu}m$ in the center to 100 ${\mu}m$ in the pellet periphery region. It was observed that the isotopic concentration ratios for minor actinides in the center of the specimen remain almost constant and increase near the pellet periphery due to the rim effect apart from the $^{236}U$ to $^{235}U$ ratio, which remains approximately constant. In addition, the distributions of local burnup were derived from the measured isotope ratios by applying the relationship between burnup and isotopic ratio for plutonium and minor actinides calculated by the ORIGEN2 code.

• Advances in nano research
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• v.7 no.4
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• pp.233-240
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• 2019

The present research work reports in-vitro anti-cancer activity of biologically synthesized ZnO nanoparticles (ZnO NPs) against human carcinoma cells viz SCC-40, SK-MEL-2 and SCC-29B using Sulforhodamine-B (SRB) Assay. ZnO NPs were synthesized by a unique and novel biological route using Temperature-gradient phenomenon where the extract of combination of Catharanthus roseus (L.) G. Don (C. roseus), Azadirachta indica (A. indica), Ficus religiosa (F. religiosa) and NaOH solution were used as synthesis medium. The morphology of the ZnO NPs was characterized by Transmission Electron Microscopy (TEM). TEM images reveal that particle size of the samples reduces from 76 nm to 53 nm with the increase in reaction temperature and 68 nm to 38 nm with the increase in molar concentration of NaOH respectively. XRD study confirms the presence of elements and reduction in crystallite size with increase in reaction temperature and NaOH concentration. The diffraction peaks show broadening and a slight shift towards lower Bragg angle ($2{\theta}$) which represents the reduction in crystallite size as well as presence of uniform strain. The FTIR spectra of the extract show transmittance peak fingerprint of Zn-O bond and presence of bioactive molecules These NPs exhibit inhibition greater than 50% for SCC-40, SK-MEL-2 and SCC-29B cell lines and more than 50% cell kill for SCC-29B cells at concentrations < $80{\mu}g/ml$. Nanoparticles with smallest size have shown better anti-cancer activity and peculiar cell-selectivity. The combination of extracts of these plants with ZnO NPs can be used in targeted drug delivery as an effective anti-cancer agent, a potential application in cancer treatment.

• Journal of Veterinary Clinics
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• v.37 no.6
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• pp.311-316
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• 2020

Biomarkers used in dogs with heartworm disease include N-terminal pro B-type natriuretic peptide (NT-proBNP) and cardiac troponin I (cTnI), which are associated with damage to the myocardium. Pulmonary hypertension is one of the clinical signs of canine heartworm disease. The purpose of this study is to investigate the change in the concentration of each biomarker, severity of pulmonary hypertension and the correlation between biomarkers according to the severity of clinical signs. Five healthy dogs and 10 heartworm-infected dogs were recruited for the study. The heartworm-infected group was classified based on the history, clinical signs, and blood assay, thoracic radiography, and echocardiography after confirming the infection according to the results of the commercial ELISA kit (SNAP test, IDEXX Laboratories, Maine, USA). NT-proBNP was higher in the severely infected group than the control group (p < 0.05); cTnI was also higher in the severely infected group than the control group (p < 0.05). The pressure gradient of pulmonary hypertension was higher in the severe group than the mild group (p < 0.05). The severity of pulmonary hypertension was correlated with NT-proBNP (r = 0.818, p < 0.01), cTnI (r = 0.894, p < 0.01). When the correlation of the two serum values for each group was examined, a correlation was not found in the mild group (r = 0.707, p = 0.182), but a correlation was found in the severe group (r = 0.9, p < 0.05). NT-proBNP and cTnI were significantly increased and correlated with severe clinical signs. Pulmonary hypertension was significant higher in the severe group than in the mild group (p < 0.05). Evaluation of blood biomarker concentration and severity of pulmonary hypertension and referring to each correlation between these indicators may be helpful to assess the severity of the heartworm disease.

• Journal of Korean Medicine for Obesity Research
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• v.20 no.2
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• pp.97-108
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• 2020

Objectives: Ephedra sinica and Wolbigachul-tang which contains Ephedra sinica are used to treat obesity in Korean medicine. The aim of this study was to analyze the quantities of ephedrine alkaloids by high-performance liquid chromatography. Methods: The analysis was performed using a YMC-Triat C18 column with operating at 25℃, and UV detection at 210 nm. The mobile phase used a gradient flow with 0.1% H3PO4 in water and acetonitrile. Specificity, linearity, precision, accuracy, limit of detection, and limit of quantification were measured for validation anaylsis. This method was applied to analyze the quantities of ephedrine alkaloids in Ephedra sinica and Wolbigachul-tang. Results: The concentration per Ephedra sinica (gram) of ephedrine and pseudoephedrine in Ephedra sinica decoction are 4.74±0.22 mg and 2.19±0.10 mg, respectively and in Wolbigachul-tang decoction are 6.39±0.34 mg and 2.97±0.21 mg, respectively. The retention time of ephedrine was 23.6 min and that of pseudoephedrine was 25.8 min, and norephedrine and methylephedrine were not detected. Conclusions: In conclusion, analyzed the concentration of ephedrine alkaloids in Ephedra sinica and Wolbigachul-tang by the developed validation method.

• Journal of Korean Society of Steel Construction
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• v.12 no.5 s.48
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• pp.617-628
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• 2000

In this study, the 4-point bending test has been performed in order to estimate the effect of TIG-dressing on fatigue strength and fatigue characteristics quantitatively for non load-carrying fillet welded joints subjected to pure bending. As a result of fatigue tests, fatigue strength of as-welded specimens has been satisfied the grade of fatigue strength prescribed in specifications of domestics and AASHTO & JSSC, and fatigue strength at $2{\times}106cycles$ of TIG-dressing specimens has been increased compared with as-welded specimens. As the result of beachmark tests, fatigue cracks have been occurred at several points, where the radius of curvature and flank angle in the weld bead toes are low, and grown as semi-elliptical cracks, then approached to fracture. As a result of finite element analysis, stress concentration factor in weld bead toes has been closely related to the flank angel and radius of curvature, and between these, the radius of curvature has more largely affected in stress concentration factor than flank angle. As a result of fracture mechanics approaches, the crack correction factor of test specimens has been largely affected on stress gradient correction factor in case a/t is below 0.4. From the relations between stress intensity factor range estimated from FEM analysis and fatigue crack growth rate, fatigue life has been correctly calculated.