• Korean Journal of Clinical Pharmacy
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• v.22 no.2
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• pp.160-166
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• 2012

Purpose: The purpose of the present study was to investigate the pharmacokinetics of urea, a new potential diagnosis reagent of Helicobacter pylori infection. Methods: Considering the mechanism of urea breath test, we determined the excretion of urea in expired air after its oral administration in rats and beagle dogs at the dose of 2 mg/kg (including 50 mCi/mmol $^{14}C$-urea 50 ${\mu}Ci/kg$ for rats and 13.5 ${\mu}Ci/kg$ for dogs). Results: Urea was rapidly disappeared from the blood circulation by 1 hr after its i.v. bolus injection, followed by a slow disappearance by 24 hr. The half-lives at the distributive phase ($t_{1/2{\alpha}}$) and post-distributive phase ($t_{1/2{\beta}}$) were 2 min and 6 hr, respectively. The bioavailability of urea was 64.3% after its oral administration. The values of the volume of distribution ($V_{dss}$) and the total body clearance ($CL_t$) after the oral administration were compatible with those after i.v. administration. The recovery of urea in the bile was about 0.1% of the dose by 24 hr after its oral administration. Urea was extensively eliminated in the urine by 48 hr. The recovery ratios of urea in the urine and expired air were about 86.8% and 2.99% of the dose by 48 hr, respectively. Moreover, urea was mostly distributed from the blood circulation to the kidney, followed by being eliminated in the urine without metabolism. The concentration of urea in the kidney was 4.0 times higher than that of plasma at 40 min after its oral administration. Conclusions: These findings indicated that oral route appears to be available for the administration of urea. Orally administered urea, thus, was considered to be useful for the diagnosis of Helicobacter pylori infection.

• Korean Journal of Applied Biomechanics
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• v.13 no.3
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• pp.81-98
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• 2003

The purpose of this study is to closely examine kinematic characteristics by jump phase of Li Xiaopeng motion in horse vaulting and provide the training data. In doing so, as a result of analyzing kinematic variables through 3-dimensional cinematographic using the high-speed video camera to Li Xiaopeng motion first performed at the men's vault competition at the 14th Busan Asian Games, the following conclusion was obtained. 1. It was indicated that at the post-flight, the increase of flight time and height and twisting rotational velocity has a decisive effect on the increase of twist displacement. And Li Xiaopeng motion showed longer flight time and higher flight height than Ropez motion with the same twist displacement of entire movement. Also the rotational displacement of the trunk at peak of COG was much short of $360^{\circ}$(one rotation) but twist displacement showed $606^{\circ}$. Likewise, Li Xiaopeng motion was indicated to concentrate on twist movement in the early flight. 2. It was indicated that at the landing, Li Xiaopeng motion gets the hip to move back, the trunk to stand up and the horizontal velocity of COG to slow down. This is thought to be the performance of sufficient landing, resulting from large security of rotational displacement of airborne and twist displacement. 3. It was indicated that at the board contact, Li Xiaopeng motion made a rapid rotation uprighting the trunk to recover slowing velocity caused by jumping with the horse in the back, and has already twisted the trunk nearly close to $40^{\circ}$ at board contact. Under the premise that elasticity is generated without the change of the feet contacting the board, it will give an aid to the rotation and twist of pre-flight. Thus, in the round-oH phase, the tap of waist according to the fraction and extension of hip joint and arm push is thought to be very important. 4. It was indicated that at the pre-flight, Li Xiaopeng motion showed bigger movement than the techniques of precedented studies rushing to the horse, and overcomes the concern of relatively low power of jump through the rapid rotation of the trunk. Li Xiaopeng motion secured much twist distance, increased rotational distance with the trunk bent forward, resulting in the effect of rushing to the horse. 5. At horse contact, Li Xiaopeng motion makes a short-time contact, and maintains horse take-off angle close to vertical, contributing to the increase of post-flight time and height. This is thought to be resulted from rapid move toward movement direction along with the rotational velocity of trunk rapidly earned prior to horse contact, and little shave of rotation axis according to twist motion because of effective twist in the same direction.

• The Korean Journal of Nuclear Medicine
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• v.4 no.2
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• pp.55-66
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• 1970

Reappraisal measurements of apparent half survival time of red cell by $^{51}Cr$ method was made and effects of blood-letting over red cell survival were observed. The study was performed on 53 normal male subjects under three different experimental conditions. 1. Group 1 Mean $^{51}Cr$ red cell half survival by ACD wash method was 29.7 days. $T\frac{1}{2}$ of Ascorbic acid method was 29.0 days in group with 100 mg dose and 29.1 days in group with 50 mg dose respectively. There was no difference between these two methods in regards to red cell half survival. No difference were noted in amount of ascorbic acid administered. 2. Group 2 As daily amount of blood loss is increased the shortening of red cell half survival was noted. Rapid phase was seen when blood loss ranged 10 to 25 ml per day, while slow phase noted when more loss amounted 25 ml or more daily. Thus, it was clear that there was more than an exponential relation between $T\frac{1}{2}$ and the amount of blood loss. 3. Group 3 $T\frac{1}{2}$ measured by cpm per whole blood was within normal range and $T\frac{1}{2}$ measured by cpm per red cell mass showed shortening tendency when compared with the former in the group measured after blood loss (from 25 ml daily up to 100 ml daily in 10 days). In the group with rather constant blood loss of 100 ml daily for 10 consecutive days revealed the significant difference in two measurements (P<0.01). 4. $T\frac{1}{2}$ in non-steady state When red cell production is increased compared with red cell destruction, $T\frac{1}{2}$ measured by cpm per red cell mass being shorter than that by cpm per whole blood. Shortening of $T\frac{1}{2}$ measured by cpm per whole blood is more prominent. if red cell destrction is enhanced and exceeds production. 5. It is clear that when expressing red cell destruction rate, $T\frac{1}{2}$ measured by cpm per whole blood is more adequate and production more consistent with cpm red cell mass. 6. $T\frac{1}{2}$ measured during blood-letting, when corrected by amount of blood loss, it remains normal. It is erroneous to use conventional equational when measuring $T\frac{1}{2}$ in non-steady. $T\frac{1}{2}$ measured by cpm per whole blood is considred more applicable in clinical evaluation.

• Resources Recycling
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• v.22 no.1
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• pp.64-71
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• 2013

Mineral carbonation has been proposed as a possible way for $CO_2$ sequestration. The electric arc furnace slags consist of calcium, magnesium and aluminum silicates in various combinations. If they could be used instead of natural mineral silicates for carbonation, considerable energy savings and $CO_2$ emissions reductions could be achieved. Indirect aqueous carbonation of the slags consists of two steps, extraction of calcium and carbonation. Acetic acid leaching of electric arc furnace slags had been already studied to extract Ca in them, but it was reported that the carbonation of the extracted $Ca^{2+}$ in the leached solution would suffer from too slow kinetics, even at high pressure of $CO_2$. In this work, to develop more efficient extraction of the electric arc furnace slags, hydrochloric acid leaching to separate calcium from them was studied, and the results were compared with the acetic acid ones. The phase boundary between $Ca^{2+}$ and $CaCO_3$ in the solution with pH was determined by thermodynamic calculations. Hydrochloric acid was more effective than acetic acid for the extraction of Ca in electric arc furnace slag, and there is a possibility to recycle an unreacted hydrochloric acid in the leached solution by electrolysis or evaporation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.1-7
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• 2017

The atomization of a liquid into multiple droplets has many important industrial applications, including the atomization of fuels in combustion processes and coating of surfaces and particles. Ultrasonic atomizing nozzle has a transducer that receives electrical input in the form of a high frequency signal from a power generator and converts that into mechanical energy at the same frequency. Liquid is atomized into a fine mist spray using high frequency sound vibrations. In coating applications, the unpressurized, low-velocity spray reduces the amount of overspray significantly because the droplets tend to settle on the substrate, rather than bouncing off it. The spray can be controlled and shaped precisely by entraining the slow-moving spray in an ancillary air stream using specialized types of spray-shaping equipment. The desired patterns of spray can be obtained using an air stream. To simulate the water mist behavior of an ultrasonic atomizing nozzle using an air stream, the Lagrangian dispersed phase model was employed using the commercial code FLUENT. The effects of the nozzle contraction shape, water droplet size and the pneumatic pressure drop on the spray characteristics were investigated to obtain the optimal condition for coating applications.

• Journal of Conservation Science
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• v.30 no.4
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• pp.395-407
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• 2014

In this study, firing temperature of bricks from the Songsanri tomb complex is interpreted based on the mineralogical and physical changes of soil samples fired at different temperature. When soil samples were burned at 500 to $1,200^{\circ}C$, phase transition of clay minerals affected the mineralogical composition and microstructure, which leaded to alteration of physical features as color, water absorption and porosity. Mineralogical composition can be assumed to vary with the temperature by mineral phase stability, however, color, water absorption, porosity and microstructure had slow change under $1,000^{\circ}C$, and had rapid change from 1,000 to $1,200^{\circ}C$. Upon the mineral and physical alteration of soil, firing temperature of bricks from the Songsanri tomb complex were estimated. Some bricks were over fired at temperature more than $1,200^{\circ}C$, some high-burned bricks were fired from 1,100 to $1,200^{\circ}C$, some bricks were fired by 900 to $1,000^{\circ}C$ and some bricks ere assumed not to be fired. Henceforward mineralogical and physical study can be applied to interpretate more precise firing temperature.

• Korean Chemical Engineering Research
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• v.48 no.3
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• pp.283-291
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• 2010

In this review, the studies on the electrochemical properties of $TiO_2$ nanotube as an anode material of lithium-ion battery, which was prepared by an alkaline hydrothermal reaction and anneling process, were investigated andanalyzed in terms of charge-dischage characteristics. Up to date, a maximum discharge capacity of $338mAh\;g^{-1}$(x=1.01) was achieved by the nanotube with $TiO_2(B)$ phase, whereas the theoretical capacity of $TiO_2$ anode was $335mAh\;g^{-1}$(x=1) in the basis of $Li_xTiO_2$ as a product of electrochemical reaction between $TiO_2$ and lithium. This was due to fast lithium transport by a shortened diffusion path provided by controlling the nanostructure of $TiO_2$, because the self-diffusion of lithium was slow in a basis of its activation energy as 0.48 eV. Due to an excellent ion storage capabilities in both the surface and the bulk phase, the $TiO_2$ nanotube could be a promising active material as both an anode of lithium-ion battery and an electrode of capacitor with high-rate performances.

• Korea-Australia Rheology Journal
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• v.21 no.4
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• pp.269-280
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• 2009

The drop formation dynamics of a shear thinning, elastic, yield stress ($\tau_o$) fluid (Carbopol 980 (poly(acrylic acid)) dispersions) in silicone oil has been investigated in a flow-focusing microfluidic channel. The rheological character of each solution investigated varied from Netwonian-like through to highly non-Newtonian and was varied by changing the degree of neutralization along the poly (acrylic acid) backbone. We have observed that the drop size of these non-Newtonian fluids (regardless of the degree of neutralisation) showed bimodal behaviour. At first we observed increases in drop size with increasing viscosity ratio (viscosity ratio=viscosity of dispersed phase (DP)/viscosity of continuous phase (CP)) at low flowrates of the continuous phases, and thereafter, decreasing drop sizes as the flow rate of the CP increases past a critical value. Only at the onset of pinching and during the high extensional deformation during pinch-off of a drop are any differences in the non-Newtonian characteristics of these fluids, that is extents of shear thinning, elasticity and yield stress ($\tau_o$), apparent. Changes in these break-off dynamics resulted in the observed differences in the number and size distribution of secondary drops during pinch-off for both fluid classes, Newtonian-like and non-Newtonian fluids. In the case of the Newtonian-like drops, a secondary drop was generated by the onset of necking and breakup at both ends of the filament, akin to end-pinching behavior. This pinch-off behavior was observed to be unaffected by changes in viscosity ratio, over the range explored. Meanwhile, in the case of the non-Newtonian solutions, discrete differences in behaviour were observed, believed to be attributable to each of the non-Newtonian properties of shear thinning, elasticity and yield stress. The presence of a yield stress ($\tau_o$), when coupled with slow flow rates or low viscosities of the CP, reduced the drop size compared to the Newtonian-like Carbopol dispersions of much lower viscosity. The presence of shear thinning resulted in a rapid necking event post onset, a decrease in primary droplet size and, in some cases, an increase in the rate of drop production. The presence of elasticity during the extensional flow imposed by the necking event allowed for the extended maintenance of the filament, as observed previously for dilute solutions of linear polymers during drop break-up.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.6
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• pp.115-121
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• 2013

This paper related with the DSE-MMA (Dithered Sign-Error MMA) that is the simplification of computational arithmetic number in blind equalization algorithm in order to compensates the intersymbol interference which occurs the passing the nonlinear communication channel in the presence of the band limit and phase distortion. The SE-MMA algorithm has a merit of H/W implementation for the possible to reduction of computational arithmetic number using the 1 bit quantizer in stead of multiplication in the updating the equalizer tap weight. But it degradates the overall blind equalization algorithm performance by the information loss at the quantization process compare to the MMA. The DSE-MMA which implements the dithered signed-error concepts by using the dither signal before qualtization are added to MMA, then the improved SNR performance which represents the roburstness of equalization algorithm are obtained. It has a concurrently compensation capability of the amplitude and phase distortion due to intersymbol interference like as the SE-MMA and MMA algorithm. The paper uses the equalizer output signal, residual isi, MD, MSE learning curve and SER curve for the performance index of blind equalization algorithm, and the computer simulation were performed in order to compare the SE-MMA and DSE-MMA applying the same performance index. As a result of simulation, the DSE-MMA can improving the roburstness and the value of every performance index after steady state than the SE-MMA, and confirmed that the DSE-MMA has slow convergence speed which meaning the reaching the seady state from initial state of adaptive equalization filter.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.2 s.332
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• pp.23-30
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• 2005

This paper describes a DLL(delay locked loop)-based multi-clock generator having the lower active stand-by power as well as a fast relocking after re-activating the DLL. for low power and high speed VLSI chip. It enables a frequency multiplication using frequency multiplier scheme and produces output clocks with 50:50 duty-ratio regardless of the duty-ratio of system clock. Also, digital control scheme using DAC enables a fast relocking operation after exiting a standby-mode of the clock system which was obtained by storing analog locking information as digital codes in a register block. Also, for a clock multiplication, it has a feed-forward duty correction scheme using multiphase and phase mixing corrects a duty-error of system clock without requiring additional time. In this paper, the proposed DLL-based multi-clock generator can provides a synchronous clock to an external clock for I/O data communications and multiple clocks of slow and high speed operations for various IPs. The proposed DLL-based multi-clock generator was designed by the area of $1796{\mu}m\times654{\mu}m$ using $0.35-{\mu}m$ CMOS process and has $75MHz\~550MHz$ lock-range and maximum multiplication frequency of 800 MHz below 20psec static skew at 2.3v supply voltage.