• Journal of computational fluids engineering
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• v.15 no.3
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• pp.24-31
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• 2010

boiling flow in vertical tube. The multiphase flow model used in this CFD analysis is the two-fluid model in which liquid(water) and gas(vapour) are considered as continuous and dispersed fluids, respectively. A wall boiling model is also used to simulate the subcooled boiling heat transfer at the heated wall boundary. The diameter and heated length of tube are 0.0154 m and 2 m, respectively. The system pressure in tube is 4.5 MPa and the inlet subcooling is 60 K. The near-wall grid size in the non-dimensional wall unit for lqiuid phase ($y^+_{w,l}$) was examined from 101 to 313 at the outlet boundary. The CFD calculations predicted the void distributions as well as the liquid and wall temperatures in tube. The predicted axial variations of the void fraction and the wall temperature are compared with the measured ones. The CFD prediction of the wall temperature is shown to slightly depend on the near-wall grid size but the axial void prediction has somewhat large dependency. The CFD prediction was found to show a better agreement with the measured one for the large near-wall grid, e.g., $y^+_{w,l}$ > 300 at the tube exit.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.3114-3114
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• 2001

During the last years phytochemistry and phytopharmaceutical applications have developed rapidly and so there exists a high demand for faster and more efficient analysis techniques. Therefore we have established a near infrared transflectance spectroscopy (NIRS) method that allows a qualitative and quantitative determination of new polyphenolic pharmacological active leading compounds within a few seconds. As the NIR spectrometer has to be calibrated the compound of interest has at first to be characterized by using one or other a combination of chromatographic or electrophoretic separation techniques such as thin layer chromatography (TLC), high performance liquid chromatography (HPLC), capillary electrophoresis (CE), gas chromatography (GC) and capillary electrochromatography (CEC). Both structural elucidation and quantitative analysis of the phenolic compound is possible by direct coupling of the mentioned separation methods with a mass spectrometer (GC-MS, LC-MS/MS, CE-MS, CEC-MS) and a NMR spectrometer (LC-NMR). Furthermore the compound has to be isolated (NPLC, MPLC, prep. TLC, prep. HPLC) and its structure elucidated by spectroscopic techniques (UV, IR, HR-MS, NMR) and chemical synthesis. After that HPLC can be used to provide the reference data for the calibration step of the near infrared spectrometer. The NIRS calibration step is time consuming, which is compensated by short analysis times. After validation of the established NIRS method it is possible to determine the polyphenolic compound within seconds which allows to raise the efficiency in quality control and to reduce costs especially in the phytopharmaceutical industry.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.44.2-44.2
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• 2019

Comets, one of the least-altered leftovers from the nascent solar system, have probably preserved the primitive structure inside, whereas their surfaces become modified from the initial states after repetitive orbital revolutions around the Sun. Resurfacing makes the surface drier and more consolidated than the bulk nuclei, creating inert refractory dust layer ("dust mantle"). Near-infrared (NIR; 1.25-2.25 m) polarimetry is theoretically expected to maximize contrast of the porosity between inner fresh and evolved dust particles, by harboring more dust constituents in the single wavelength than the optical; thus, intensifies electromagnetic interaction in dust aggregates. Despite such an advantage, only a few studies have been made in this approach mainly due to the limited accessibility of available facilities. Herein, we present our new multi-band NIR polarimetric study of near-Earth object 252P/LINEAR over 12 days near perihelion, together with the results of optical (0.48-0.80m) imaging observations and backward dynamical simulation of the comet. Based on the results, we will characterize the dust properties of the comet and discuss the possible environmental (temperature and UV radiation) effects that could produce the observed phenomena.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.441-442
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• 2005

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.251-251
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• 2003

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1285-1285
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• 2001

For NIR measurements of papers normally diffuse reflectance accessories are used which can provide a large sampling area. The in-line process control FT-NIR spectrometer MATRIX-E enables the contactless measurement of paper samples of low silicone coat weights on label-stocks in a paper converting factory. For this study concentrations of silicone between 0 and 2 g/$m^2$ on various paper substrates were included in a quantitative method. The aim was to achieve an absolute value for the deviation from the target value of 1 g/$m^2$ during continuous movement of the paper with velocities around 400 numinute. Influences from the uncoated paper type due to supplier, color, opacity, area densities, pre-coating as well as different compounds of the agent silicone were investigated and it was found that all these papers can be represented in one PLS-model. Especially the fact that silicone as an element is present in clay coated papers is of no consequence to the measurements with MATRIX-E. Moreover during in-line installations the variation of the moisture contents in the moving paper due to variable machine velocities as well as the reflecting material of the cylinder have to be considered. It is shown that the result of the in-line calibration has the same prediction ability compared to lab scale results(Root Mean Square Error of Cross-Validation RMSECV = 0.034 g/$m^2$).

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1193-1193
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• 2001

For NIR measurements of papers normally diffuse reflectance accessories are used which can provide a large sampling area. The in-line process control FT-NIR spectrometer MATRIX-E enables the contactless measurement of paper samples of low silicone coat weights on label-stocks in a paper converting factory. For this study concentrations of silicone between 0 and 2 g/㎡ on various paper substrates were included in a quantitative method. The aim was to achieve an absolute value for the deviation from the target value of 1 g/㎡ during continuous movement of the paper with velocities around 400 m/minute. Influences from the uncoated paper type due to supplier, color, opacity, area densities, pre-coating as well as different compounds of the agent silicone were investigated and it was found that all these papers can be represented in one PLS-model. Especially the fact that silicone as an element is present in clay coated papers is of no consequence to the measurements with MATRIX-E. Moreover during in-line installations the variation of the moisture contents in the moving paper due to variable machine velocities as well as the reflecting material of the cylinder have to be considered. It is shown that the result of the in-line calibration has the same prediction ability compared to lab scale results (Root Mean Square Error of Cross-Validation RMSECV = 0.034 g/㎡).

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.86.2-86.2
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• 2012

We present the study of association between sub-photospheric flow and photospheric magnetic fields of active regions respectively derived from the local helioseismology and observed magnetic fields. It is believed that the energetic transients, e.g., flares and CMES, are caused by changes in magnetic and velocity field topologies in solar atmosphere. These changes are essentially brought about by the magnetic fields that are rooted beneath the photosphere where they interact and get affected by sub-photospheric flows. Therefore, we expect the topology of sub-surface flows to be correlated with the observable topology of magnetic fields at the photosphere and higher layers. In order to examine the correlation, if any, we computed the near photospheric flows and photospheric magnetic fields using the Doppler velocity and magnetic fields observations, respectively, provided by the SDO/HMI. The high resolution Doppler observations from the HMI enabled us to compute the very high p-modes parameters which sample the sub-photosphere shallow near the photosphere. Furthermore, we compute the sub-photospheric flow topology parameters, e.g., vorticity, kinetic helicity, and photospheric magnetic field topology parameters, e.g., magnetic helicity, from the magnetic fields observations to compare their associations. We present the result of the analysis in the paper.

• Korean journal of applied entomology
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• v.33 no.4
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• pp.250-256
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• 1994

Flight behavior of Mntsucoccus thunbergianae males and their response to the synthetic sex pheromone, (6R.lOR)-matsuone, were studied in Pinus thunbergiana forests More males were flying around the tree crown than near the ground. A dispenser loaded w~th 50 vg of the pheromone appeared to affect the density of male flights less than 10 meters Sticky traps with 50 pg of the pheromone attracted flylng males, but those with 1 pg were not effectwe in a forest wlth high crown closure, more males were tmpped at upper crown level than near the ground whereas males appeared to be more responsive to pheromone near the ground in a forest with low crown closure Monitoring new scale iniestations with pheromone mps was much more effective than egg sac surveys, the customary detecting procedures Maiing disruption was not achieved by placing 32 mg of pheromone m a space of l X l X l meter.

• Journal of Veterinary Clinics
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• v.18 no.4
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• pp.442-447
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• 2001

A 2-year-old 4.0-kg female Shih Tzu with history of hematemesis and melena was referred to Veterinary Medical Teaching Hospital, Seoul national University for further evaluation and treatment. During physical examination, the dog revealed mild depression, dry mucous membrane and abdominal pain. Hematologic values were normal and serum chemical values showed increased serum bile acid (53.47 umol/l, preprandial), fasting serum ammonia concentration (184 g/dl), alanine transferase (98 U/L), alkaline phosphatase (871 U/L) and gamma glutamyl transpeptidase (21 U/L), and decreased blood urea nitrogen (4 mg/dl), total protein (4.1 g/dl) and albumin (1.2 g/dl). Microhepatica was shown in abdominal radiography. During the ultrasound examination, dilated tortuous vein communicating with caudal vena cava ws observed near the stomach. Intraoperative jejunal vein portography was performed during laparotomy to confirm the location and size of shunt vessel. According to history taking, physical examination, hematologic and serum chemical examination and radiographic study, it was diagnosed as single extrahepatic portosystemic shunt. The anomalous vessel (7 mm, o.d.) that enter the caudal vena cava from the left gastric vein, near the level of the diaphragm, was identified. A Ameroid constrictor (5 mm, i.d.) was applied to the shunting vessel near the caudal vena cava. Hematologic and serum chemical values recovered gradually and were revealed normal values 4 months after surgery. Four month after surgery serum bile acids concentrations were 0.56 $\mu$mol/l (preprandial) and 18.45 umol/l (postprandial). Abdominal radiograph showed normal gastric axis and it revealed normal size of the liver. Fine texture and increased echogenecity of liver and enlargement of portal vein were shown in ultrasonography. Single extrahepatic portosystemic shunt might be treated surgically using Ameroid constrictor.