• 대한기계학회논문집B
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• 제30권7호
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• pp.612-621
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• 2006

Drawing is a mechanical operation attenuating material thickness to an appropriate level for the next processing or end usage. When the input material has a form of bundle or bundles made of very thin and long shaped wires or fibers, this attenuation operation is called 'bundle drawing' or 'drafting'. Bundle drawing is being used widely in manufacturing micro sized wires or staple yarns. However, the bundle processed by this operation has more or less defects in the evenness of linear density. Such irregularities cause many problems not only for the product quality but also for the efficiency of the next successive processes. In this research a mathematical model for the dynamic behavior of the bundle fluid is to be set up on the basis of general physical laws containing physical variables, i.e. linear density and velocity as the dynamic state variables of the bundle fluid. The governing equations resulting from the modeling show that they appear in a slightly different form from what they do in a continuum fluid. Then, the governing equations system is simplified in a steady state and the bundle dynamics is simulated, showing that the shape of the velocity profiles depends on two model parameters. Experiments confirm that the model parameters are to be well adjusted to show a coincidence with the theoretical analysis. The higher the drawing ratio and drawing speed we, the more sensitive becomes the bundle flow to exogenous disturbances.

• Advances in Traditional Medicine
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• 제8권3호
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• pp.311-315
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• 2008

The objective of the study was to investigate the antihyperlipidemic activity of alcoholic extract of Pongamia pinnata Linn. (PPAE) leaves in rats fed with high fat diet (HFD). PPAE was administered orally in the divided doses of 250 and 500 mg/kg/day for 30 days in HFD fed rats. Body weights were observed and the analysis of serum lipid profile was carried out on day 30. Marked decrease in the body weight, total cholesterol (TC), triglycerides (TG), low density lipoprotein (LDL) and very low density lipoprotein (VLDL) whereas significant increase in the levels of high density lipoprotein (HDL) were observed after treatment with PPAE. However, PPAE in a dose of 250 mg/kg did not show significant (P < 0.05) increase in HDL levels. The PPAE also lowered TC: HDL-c and LDL: HDL-c ratios significantly suggesting it's antihyperlipidemic and cardioprotective potential. The present work reveals that PPAE at the dose of 500 mg/kg/day exhibited significant (P < 0.01) antihyperlipidemic effects.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.526-526
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• 2012

DC magnetron discharges were studied using three-dimensional self-consistent particle-in-cell and Monte Carlo collisional (PIC-MCC) simulation codes. Two rectangular sputter sources (120 mm * 250 mm and 380 mm * 200 mm target sizes) were used in the simulation modeling. The number of incident ions to the Cu target as a function of position and simulation time was obtained. The target erosion profile was calculated by using the incident ions and the sputtering yields of the Cu target calculated with SRIM codes. The maximum ion density of the ion density distribution in the discharge was about $10^{10}cm^{-3}$ due to the calculation speed limit. The result may be less than one or two order of magnitude smaller than the real maximum ion density. However, the target erosion profiles of the two sputter sources were in good agreement with the measured target erosion profiles except for the erosion profile near the target surface, in which which the measured erosion width was broader than the simulation erosion width.

• Nuclear Engineering and Technology
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• 제40권6호
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• pp.477-488
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• 2008

The objective of the paper is to analyze the thermally induced density wave oscillations in water cooled boiling water reactors. A transient thermal hydraulic model is developed with a characteristics-based implicit finite-difference scheme to solve the nonlinear mass, momentum and energy conservation equations in a time-domain. A two-phase flow was simulated with a one-dimensional homogeneous equilibrium model. The model treats the boundary conditions naturally and takes into account the compressibility effect of the two-phase flow. The axial variation of the heat flux profile can also be handled with the model. Unlike the method of characteristics analysis, the present numerical model is computationally inexpensive in terms of time and works in a Eulerian coordinate system without the loss of accuracy. The model was validated against available benchmarks. The model was extended for the purpose of studying the flow-induced density wave oscillations in forced circulation and natural circulation boiling water reactors. Various parametric studies were undertaken to evaluate the model's performance under different operating conditions. Marginal stability boundaries were drawn for type-I and type-II instabilities in a dimensionless parameter space. The significance of adiabatic riser sections in different boiling reactors was analyzed in detail. The effect of the axial heat flux profile was also investigated for different boiling reactors.

• Journal of Pharmaceutical Investigation
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• 제34권3호
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• pp.201-207
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• 2004

In order to develop an optimum formulation for iontophoretic flux of vitamine C 2-phosphate (VCP), we have prepared three different hydrogels containing VCP, using carbopol, HPMC and poloxamer, and iontophoretic flux through hairless mouse skin from these hydrogels was carried out. Drug stability in phosphate buffer (PBS) solution (pH 7.4) with and without current application was studied. The effect of various factors, such as drug concentration, current density, and current profile on skin flux was also investigated. Stability study indicated that VCP in PBS (pH 7.4) solution was stable under the experimental condition, irrespective of the presence of current. Cathodal delivery increased the flux markedly, whereas the anodal and passive flux was negligible. Thus, cathodal delivery was used in all experiments. Flux increased as the drug concentration (2.5, 5.0, 7.5%) and current density $(0.2,\;0.4,\;0.6\;mA/cm^2)$ increased. Pulsed application of the current showed lower flux than constant current application. The results obtained suggest that VCP can be delivered into the skin and the amount delivered can be controlled by varying hydrogel, current density, drug concentration and current application profile.

• 천문학회지
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• 제40권4호
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• pp.119-122
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• 2007

From the HCN observations of dense molecular cloud L694-2, Lee et al.(2007) determined internal distributions of density and velocity for the cloud. The density profile collaborates roughly with the Bonnor- Ebert gas sphere, but the velocity field departs significantly from the result of numerical simulations that are started from the BE sphere. Taking L694-2 as an example of collapsing clouds, we have performed a series of collapse simulations and determined initial configurations for the cloud in such a way that the resulting density and velocity profiles both match with the empirically deduced ones. Among many trial configurations the cloud which is initially uniform in density and bound by an expanding envelop depicts most closely the empirically obtained profiles of both density and velocity.

• 한국동물학회지
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• 제37권4호
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• pp.597-604
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• 1994

Membranes obtained from the normal human RBC population were separated by continuous sucrose density gradient centrifugation and the density-fractionated membranes were then examined for changes in molecular markers. This study focuses on changes of (i) the membrane protein profile, (ii) differences in membrane-associsted enzyme activities, and (iii) the amount of autologous IgG bound. The following observations were made: (i) ratios for band 4. la over the sum of bands (4. la + 4.Ib) ranged from 0.58 to 0.79 for membranes of lowest density; (ii) significant changes in bound glyceraldehyde-3-phosphate dehydrogenase and acetvlcholinesterase activities were found; (iii) the amounts of autolosous IgG's attached to the red blood cells was highest in the membrane fraction of lowest density.

• 천문학회보
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• 제40권1호
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• pp.68.1-68.1
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• 2015

Gravitational collapse is a dynamical process associated with star formation. One observational evidence of such infall motion is so called "blue asymmetry" profile, which is the optically thick line profile with the intensity peak skewed blueward relative to the intensity peak of optically thin lines. We analyzed both HCN J=1-0 and HNC J=1-0 line profiles to study the inflow motion in different evolutionary stages of massive star formation; Infrared dark clouds (IRDCs), High-mass protostellar object (HMPOs), and Ultra-compact HII regions (UCHIIs). The infall asymmetry in the HCN spectra seems to be more prevalent than the HNC spectra throughout all the three evolutionary phases. The prevalence of the blue profile in the HCN spectra is found in every evolutionary stage, with IRDCs showing the largest blue excess. In the case of the HNC spectra, only IRDCs show the blue excess statistically significant. These results suggest that HCN may be a better infall tracer in massive star forming region. In addition, even though the characteristics of the blue profile largely depend on the suitable combination of optical depth and critical density, our analyses also indicate that IRDCs may have the most active infall process compared to other evolutionary phases.

• 한국군사과학기술학회지
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• 제22권5호
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• pp.674-686
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• 2019

In this paper, we will discuss the absolute angular error control mode for the Gun/Turret driving system. The Gun/Turret driving controller receives absolute angular error calculated from the fire control system (FCS). Thus, the Gun/Turret driving controller is subjected to step command to cause residual vibration and system unstable. In order to reduce residual vibration and to ensure the system stability, we propose an error motion profile method with two types of trapezoidal and S-Curve. The validity of the proposed error motion profile method is confirmed via simulation by observing that the resulting position error, driving power, and power density satisfied the control performance.

• 대기
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• 제15권3호
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• pp.149-153
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• 2005

A balloon-borne Optical Particle Counter (hereafter "OPC Sonde"), which was developed by the atmospheric research group of Nagoya University, is used for getting the information of vertical profile of particle size and concentration in Anmyeon ($36^{\circ}32^{\prime}N$ $126^{\circ}19^{\prime}E$) on 18 March 2005. A range of five different particle sizes is shown in the vertical profile of aerosol number density estimated from the OPC Sonde. It was found that small size particles have vertically larger aerosol number density than relatively big ones. For all size ranges the vertical aerosol number density shows a decreased pattern as the altitude becomes higher. The aerosol number density of $0.3{\sim}0.5{\mu}m$, $0.5{\sim}0.8{\mu}m$, $0.8{\sim}1.2{\mu}m$ size ranges at the 10km height, which is the tropopause approximately, are $1,000,000ea/m^3$, $100,000ea/m^3$, $10,000ea/m^3$ respectively. The data of OPC Sonde are also compared with the data of PM10 $\beta$-ray) and Micro Pulse Lidar which are operating at Korea Global Atmosphere Watch Observatory in Anmyeon.