• The Korean Journal of Physiology
• /
• v.25 no.2
• /
• pp.189-200
• /
• 1991

During the past few years it has been proposed that lithium clearance can be used as a reliable measure for the outflow of tubular fluid from the proximal tubule. This study was aimed to characterize the inflow dependent reabsorption of Na in renal tubule beyond the proximal tubule. For this purpose, lithium clearance was used as a measure for the inflow from the proximal tubule and the changes in reabsorption fraction of Na and water were determined in rabbits. Rabbits were pretreated with hypotonic saline solutions for an hour (50 mM/L NaCl, 20 ml/hr/kg). And then a hypertonic solution of 500 mM/L NaCl (20 ml/kg) was administered intraperitoneally in conjunction with a bolus of LiCl solution (2 mM/kg, i.v.) for conditioning the $C_{Li}$ and urine flow rate. To rule out the effect of $Li^+$ on tubular functions, a bolus of NaCl solution (2 mM/kg, i.v.) was administered. Fifteen, thirty, and sixty minutes after injection of hypertonic saline arterial blood and urine samples were taken. Urinary and plasma concentrations as well as urinary output of $Li^+,\;Na^+\;and\;K^+$ were measured. From these $C_{Li},\;C_{Na}$ and the reabsorption fraction of Na and water $(Fr_{Na}\;&\;FrH_2O)$ were calculated. These results were compared with those from control groups in which the same amount of isotonic saline (145 mM/L NaCl) and of 15% dextran solution were administered in the same way as that in experimental group. Followings are the results obtained. 1) The plasma concentration of $Na^+$ in rabbits injected with hypertonic saline reached the peak value after 15 min and thereafter no significant change was observed. Hematocrit values did not show any change, while urinary excretion of $Na^+$ increased markedly during the first 15 min and decreased thereafter. These results were not affected by an injection of a small amount of LiCl. 2) The clearances of $Li^+,\;Na^+\;and\;K^+$ in rabbits injected with hypertonic saline and LiCl solution decreased. 3) In spite of the variation in $C_{Li},\;Fr_{Na}$ did not show any significant change while $FrH_2O$ increased gradually. 4) $C_{Li}$ decreased also in rabbits received isotonic saline. $Fr_{Na}$ tended to be higher than that in hypertonic saline group, while $FrH_2O\;and\;Fr_{Na}$ did not associated with the decrease in $C_{Li}$. 5) $C_{Li}$ of the rabbits received dextran solution fluctuated persistently and $Fr_{Na}\;and\;FrH_2O$ did not change in along with $C_{Li}$ although $Fr_{Na}$ had a tendency to be higher than that in hypertonic saline group. 6) From the above results it was concluded that: (a) In rabbits with normal body store of $Na^+$, the $Fr_{Na}$ of renal tubule beyond proximal tubule. calculated from $C_{Li}$ as a measure of inflow from proximal tubule is constant in spite of variations in $C_{Li}$. (b) The $FrH_2O$ calculated from $C_{Li}$ is dependent largely upon ADH rather than inflow from proximal tubule. (c) When there is a decrease in plasma $Na^+$ concentration or ineffective body fluid. $Li^+$ reabsorption may occur in the thick segnent of Henle's loop and hence the determination of $Fr_{Na}$ and $FrH_2O$ will not be easy one, but $Fr_{Na}$ is constant under the same experimental conditions.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.16 no.1
• /
• pp.105-115
• /
• 2014

A numerical analysis on the smoke behavior and evacuee safety has been performed with computational fluid dynamics. The purpose of this study is to build computational processes for an evacuation and prevention of a fire disaster of a 3 km-length tunnel in Korea. To save computational cost, 1.5 km of the tunnel that can include a few cross-passing tunnels is considered. We are going to assess the fire safety in a road tunnel according to the smoke level, which consists of the smoke density and the height from the floor. The smoke density is obtained in detail from three-dimensional unsteady CFD analysis. To obtain proper temperature distributions on the tunnel wall, one-dimensional conduction equation is considered instead of an adiabatic wall boundary or a constant heat flux. The tunnel considered in this study equips the cross passing tunnels for evacuees every 250 m. The distance is critical in both safety and economy. The more cross passing tunnels, the more safe but the more expensive. Three different jet fan operations can be considered in this study; under- and over-critical velocities for normal traffic condition and 0-velocoty operation for the traffic congestion. The SE (smoke environment) level maps show a smoke environment and an evacuating behavior every moment.

• Korean Journal of Clinical Pharmacy
• /
• v.16 no.1
• /
• pp.23-27
• /
• 2006

Doxorubicin (DXR) is a type of anti-cancer drug called an 'anthracycline glycoside', It works by impairing DNA synthesis, a crucial feature of cell division, and thus is able to target rapidly dividing cells. Doxorubicin is a very serious anti-cancer medication with definite potential to do great harm as well as great good. A liquid chromatography-tandem mass spectroscopy (LC-MS/MS) method was developed to identify and quantify DXR in small-volume biological samples. After the addition of internal standard (IS, $5{\mu}L\;of\;1{\mu}M/ml$ daunorubicin methanol solution) into the serum sample, the drug and IS were extracted by methanol. Following vortex for a 1min and centrifugation at 15,000g for 10 min the organic phase was transferred and evaporated under a vacuum. The residue was reconstituted with $350{\mu}L$ of mobile phase and $10{\mu}L$ was injected into C18 column with mobile phase composed of 0.05M ammonium acetate (0.1 M acetic acid adjusted to pH 3.5) and acetonitrile (40:60, v/v). The flow rate was kept constant at $350{\mu}L/min$. The ions were quantified in the multiple reaction mode (MRM), using positive ions, on a triple quadrupole mass spectrometer. The lower limits of quantification for Doxorubicin in plasma and small tissues were approximately 0.5 ng/mL and 0.5 ng/mL respectively. Intra- and inter-assay accuracy (% of nominal concentration) and precision (% CV) for all analytes were within 15%, respectively.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.12 no.3
• /
• pp.179-189
• /
• 2014

Pyroprocessing has been developed for the purpose of resolving the current spent nuclear fuel management issue and enhancing the recycle of valuable resources. An electrolytic reduction of the pyroprocessing is a process to reduce oxides into metals using LiCl as an electrolyte and requires a post-treatment process due to the inclusion of residual salt in porous metal products. A vacuum distillation has been adopted for various molten salt systems and could be applied to the post-treatment process of the electrolytic reduction. The residual salt in the metal products includes LiCl, alkali chlorides, and alkaline earth chlorides. In this paper, vapor pressures of chlorides have been estimated and the composition changes on the residual liquid during the vacuum distillation process have been calculated. A model combining a material balance and vapor-liquid equilibrium relations has been proposed under a constant vapor discharging flow rate and liquid composition changes have been calculated using the vapor pressures with respect to a dimensionless time. The behaviors have been compared with temperature and molten salt composition changes to simulate the process condition variation. The distillation of the residual salt has been dominated by LiCl which is the main component of the salt and CsCl of which vapor pressure is higher than that of LiCl would be readily removed. RbCl exhibits similar vapor pressure with LiCl and maintains its composition. However, $SrCl_2$ and $BaCl_2$ of which vapor pressures are much lower than that of LiCl are concentrated with time and expected to be possibly precipitated during the distillation when the initial compositions are increased.

• Applied Chemistry for Engineering
• /
• v.4 no.3
• /
• pp.537-543
• /
• 1993

The effect of agitation on liquid-liquid dispersion was investigated in an immisible liquid phase(n-hexane/water) system. Four different types of six-bladed turbine impellers were used: a flat blade, two screen blades and a solid edged 60 mesh screen blade. We found that the extent of dispersion of organic phase and power consumption of agitator were decreased in the order of flat, solid edged, 60 mesh, and 40 mesh blades at same agitation speed. And the minimum agitation speed for complete dispersion of organic phase was increased with increasing volume fraction of organic phase. Also, mean diameter of liquid droplets of dispersed phase was decreased with increasing agitation speed and it was increased in the order of solid edged, flat, 60 mesh, and 40 mesh screen blades at same agitation speed. At complete dispersion, the minimum power consumption was not vary significantly with impeller blade types, but the solid edged screen blade impeller gave the smallest and uniform sizes of liquid droplets, and it had a good performance for liquid-liquid dispersion. In this condition, Power number was not affected by Reynolds number and it was constant in turbulent flow region, and Sauter mean diameter($d_{32}$) of liquid droplets was expressed as a function of volume fraction of organic phase(${\phi}$) and Weber number($N_{We}$) as follows: $d_{32}/D=a(1+b{\phi})N_{We}{^{-0.6}}$.

• Journal of Environmental Science International
• /
• v.12 no.1
• /
• pp.47-54
• /
• 2003

This paper have examined the optimum combination of SNCR and SCR by varying SNCR injection temperature and NSR ratio along with SCR space velocity. NOx reduction experiments using a SNCR/SCR combined process have been conducted in simple NO/NH$_3$/O$_2$ gas mixtures. Total gas flow rate was kept constant 4 liter/min throughout the SNCR and SCR reactors, where initial NOx concentration was 500 ppm in the presence of 5% O$_2$. Commercial catalyst, sulfated V$_2$O$\_$5/-WO$_3$/TiO$_2$, was used for SCR NOx reduction. The residence time and space velocity were around 1.67 sec, 2,400 h$\^$-1/ and 6,000 h$\^$-1/ in the SNCR and SCR reactors, respectively. SNCR NOx reduction effectively occurred in a temperature window of 900-950$^{\circ}C$. About 88% NOx reduction was achieved with an optimum temperature of 950$^{\circ}C$ and NSR=1.5. SCR NOx reduction using commercial V$_2$O$\_$5/-WO$_3$-SO$_4$/TiO$_2$ catalyst occurred in a temperature window of 200-450$^{\circ}C$ 80-98% NOxreduction was possible with SV=2400 h$\^$-1/ and a molar ratio of 1.0-2.0. A SNCR/SCR(SV=6000 h$\^$-1/) combined process has shown same NOx reduction compared with a stand-alone SCR(SV=2400 h$\^$-1/) unit process of 98% NOx reduction. The NH$_3$-based chemical could routinely achieve SNCR/SCR combined process total NOx reductions of 98% with less than 5 ppm NH$_3$ slip at NSR ranging from about 1.5 to 2.0, SNCR temperature of 900$^{\circ}C$-950$^{\circ}C$, and SCR space velocity of 6000 h$\^$-1/. Particularly, more than 98% NOx reduction was possible using the combined process under the conditions of T$\_$SNCR/=950$^{\circ}C$, T$\_$SCR/=350$^{\circ}C$, 5% O$_2$, SV=6000 h$\^$-1/ and NH$_3$/NOx=1.5. A catalyst volume was about three times reduced by SNCR/SCR combined process compared with SCR process under the same controlled conditions.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.10
• /
• pp.1217-1224
• /
• 2014

This paper provides a practical scaling method to solve an old problem for scaling and developing the speed and resistance of a model to full-scale submarine in fully submerged underwater test. In every experimental test in towing tank, water tunnel and wind tunnel, in the first step, the speed of a model should be scaled to the full-scale vessel (ship or submarine). In the second step, the obtained resistance of the model should be developed. For submarine, there are two modes of movement: surface and submerged mode. There is no matter in surface mode because, according to Froude's law, the ratio of speed of the model to the full-scale vessel is proportional to the square root of lengths (length of the model on the length of the vessel). This leads to a reasonable speed and is not so much for the model that is applicable in the laboratory. The main problem is in submerged mode (fully submerged) that there isn't surface wave effect and therefore, Froude's law couldn't be used. Reynold's similarity is actually impossible to implement because it leads to very high speeds of the model that is impossible in a laboratory and inside the water. According to Reynold's similarity, the ratio of speed of the model to the full-scale vessel is proportional to the ratio of the full-scale length to the model length that leads to a too high speed. This paper proves that there is no need for exact Reynold's similarity because after a special Reynolds, resistance coefficient remains constant. Therefore, there is not compulsion for high speeds of the model. For proving this finding, three groups of results are presented: two cases are based on CFD method, and one case is based on the model test in towing tank. All these three results are presented for three different shapes that can show; this finding is independent of the shapes and geometries. For CFD method, Flow Vision software has been used.

• Applied Chemistry for Engineering
• /
• v.23 no.1
• /
• pp.86-92
• /
• 2012

A characteristic study of chlorine dioxide generation by the electrolysis system was performed after chlorite ($ClO_2^-$) is adsorbed from sodium chlorite by a polymer ion exchange resin. A strongly basic anion exchange resin was used and a Ti plate coated with Ru and Ir was used as an electrode. Various parameters such as reaction stirring velocity, reaction temperature, chlorine dioxide product concentration, ion exchange resin content and product maker type for the adsorption quantity in the chlorite adsorption of ion exchange resin were investigated and found the ion exchange resin with the maximum adsorption quantity. A generation trend of chlorine dioxide was observed by the electrolysis system and optimum conditions on the desired value were found using response surface design of DOE (Design of Experiments). The strongly basic anion exchange resin with the maximum adsorption quantity was SAR-20 (TRILITE Gel type II) and the adsorption quantity was around 110 mg/IER (g). Observed generation optimum conditions of chlorine dioxide were constant-current (electrode area base; $A/dm^2$) and flow rate of $N_2$ gas (4.7 L/min) at the desired value of sterilization (900~1000 ppm, 1 h).

• Nuclear Engineering and Technology
• /
• v.25 no.4
• /
• pp.539-547
• /
• 1993

A stochastic approach using continuous time Markov process is presented to model the one-dimensional nuclide transport in fractured rock media as a further extension for previous works［1-3］. Nuclide transport of decay chain of arbitrary length in the single planar fractured rock media in the vicinity of the radioactive waste repository is modeled using a continuous time Markov process. While most of analytical solutions for nuclide transport of decay chain deal with the limited length of decay chain, do not consider the case of having rock matrix diffusion, and have very complicated solution form, the present model offers rather a simplified solution in the form of expectance and its variance resulted from a stochastic modeling. As another deterministic way, even numerical models of decay chain transport, in most cases, show very complicated procedure to get the solution and large discrepancy for the exact solution as opposed to the stochastic model developed in this study. To demonstrate the use of the present model and to verify the model by comparing with the deterministic model, a specific illustration was made for the transport of a chain of three member in single fractured rock medium with constant groundwater flow rate in the fracture, which ignores the rock matrix diffusion and shows good capability to model the fractured media around the repository.

• Current Research on Agriculture and Life Sciences
• /
• v.33 no.2
• /
• pp.41-47
• /
• 2015

This study calculated the overall heat transfer coefficient (U-value) of greenhouse covering materials with thermal screens using a simulation model and then estimated the validity of the calculated results by comparison with measured values. The U-value decreased gradually as the thickness of the air space between the double glazing increased, and then remained essentially constant at thicknesses exceeding 25 mm. The U-value also increased with the difference in temperature between the inside and outside of the hot box. The vigorous convective heat transfer between two plastic films caused unsteady heat flow and then created a nonlinear temperature distribution in the air space. The distance did not affect the U-value at distances of 50~200 mm between the plastic covering and thermal curtain. The numerical calculation results, with and without sky radiation, were in accord with the experimental results for a $30^{\circ}C$ temperature difference between the inside and outside of the hot box. In conclusion, a reliable U-value can be calculated for a temperature difference of $30^{\circ}C$ or more between the inside and outside of the hot box.