• Analytical Science and Technology
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• v.28 no.2
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• pp.125-131
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• 2015

A method was developed and fully validated for the determination of terbutaline, a β₂-receptor agonist, in human plasma. Plasma samples were prepared by solid-phase extraction with Sep-Pak silica, followed by high-performance liquid chromatography (HPLC). The terbutaline was pre-separated from the interfering components in plasma on a Luna C18 (2) column, and terbutaline and salbutamol as an internal standard were resolved and determined on a Luna Silica column. The two columns were connected by a switching valve equipped with silica pre-column. The pre-column was used to concentrate the terbutaline in the eluent from the C18 column before back-flushing onto the silica column with fluorescence detection at an excitation/emission wavelength of 276/306 nm. The method was shown to be specific by testing six different human plasma sources. Linearity was established for a concentration range of 0.4-20.0 ng/mL with a correlation coefficient of 0.9999. The lower limit of quantitation was 0.4 ng/mL with a precision of 10.1% as C.V.%.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.1
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• pp.68-75
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• 2015

In this paper, unsteady characteristics of pressure in solid rocket motor were analyzed by using response of pintle actuation, pressure and thrust data from ground test. Pressure and thrust in solid rocket motor can be controlled in real time by varying nozzle throat area with pintle, installed in the valve. Unsteady characteristics of pressure can be observed in this system occurred by various reasons. Two critical reasons, error of pintle actuation and ablation of center tube, are found and effects of each reason can be analyzed individually by re-prediction of pressure with response of pintle actuation and analyzing thrust to pressure ratio.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.507-510
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• 2009

The small size of hybrid rocket using PE-$LN_2O$ was designed, constructed and launched for a development basic technology of Hybrid rocket vehicle. The hybrid engine ignition system was designed with valve system using external actuator and confirmed working without any fault. To design fuel grain an internal ballistics design was carried out, and to estimate rockets flight path an external ballistics analysis was carried out. So the rocket was designed and constructed, and the launch test proves that hybrid rocket's design was suitable. The hybrid rocket(weight : 9kg, diameter : 110 mm, height : 1.7 m) was launched successfully. But parachute was deployed on mid-flight and the mission could not finish its purposed flight. Some of problems were found in this activity but next launch vehicle will be improved.

• Journal of Biosystems Engineering
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• v.29 no.6 s.107
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• pp.521-530
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• 2004

The solar powered water pump is very ideal equipment because solar power is more intensive when the water is more needed in summer and it is very helpful in the rural area, in which electrical power is not available. The average solar radiation power is $3.488\;kWh/(m^2{\cdot}day)$ in Korea. In this study, the experimental system of the water pump driven by the radiation energy were designed, assembled, tested and analyzed fur realizing the solar powered water pump. Energy conversion ken radiation energy to mechanical energy by using n-pentane as operating material was done and the water pumping cycles were able to be continued. The quantity of the water pumped per cycle ranged from 2 L to 10 L depending on the level of the valve open area far the vapour supply. The average quantity was about 4,366 cc. The thermal efficiency was about $0.018\%$. The pressure level of the n-pentane vapour in flash tank was about $110\~150\;kPa$ and that in the water tank was $93\~130\;kPa$. The pressure in the condenser during cycles was maintained as about 70 kPa. The condensation of the n-pentane vapour in the water tank was increased with the cycles even though the internal and external insulation were done. Air tank performance was better with increasing of the water piston displacement and the water could be pumped with the water piston displacement becoming higher than 6,500 cc.

• Tuberculosis and Respiratory Diseases
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• v.81 no.2
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• pp.106-115
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• 2018

Chest tube insertion is a common procedure usually done for the purpose of draining accumulated air or fluid in the pleural cavity. Small-bore chest tubes (${\leq}14F$) are generally recommended as the first-line therapy for spontaneous pneumothorax in non-ventilated patients and pleural effusions in general, with the possible exception of hemothoraces and malignant effusions (for which an immediate pleurodesis is planned). Large-bore chest drains may be useful for very large air leaks, as well as post-ineffective trial with small-bore drains. Chest tube insertion should be guided by imaging, either bedside ultrasonography or, less commonly, computed tomography. The so-called trocar technique must be avoided. Instead, blunt dissection (for tubes >24F) or the Seldinger technique should be used. All chest tubes are connected to a drainage system device: flutter valve, underwater seal, electronic systems or, for indwelling pleural catheters (IPC), vacuum bottles. The classic, three-bottle drainage system requires either (external) wall suction or gravity ("water seal") drainage (the former not being routinely recommended unless the latter is not effective). The optimal timing for tube removal is still a matter of controversy; however, the use of digital drainage systems facilitates informed and prudent decision-making in that area. A drain-clamping test before tube withdrawal is generally not advocated. Pain, drain blockage and accidental dislodgment are common complications of small-bore drains; the most dreaded complications include organ injury, hemothorax, infections, and re-expansion pulmonary edema. IPC represent a first-line palliative therapy of malignant pleural effusions in many centers. The optimal frequency of drainage, for IPC, has not been formally agreed upon or otherwise officially established.

• Nuclear Engineering and Technology
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• v.51 no.6
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• pp.1540-1553
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• 2019

A nuclear power plant (NPP) is a highly complex system-of-systems as manifested through its internal systems interdependence. The negative impact of such interdependence was demonstrated through the 2011 Fukushima Daiichi nuclear disaster. As such, there is a critical need for new strategies to overcome the limitations of current risk assessment techniques (e.g. the use of static event and fault tree schemes), particularly through simulation of the nonlinear dynamic feedback mechanisms between the different NPP systems/components. As the first and key step towards developing an integrated NPP dynamic probabilistic risk assessment platform that can account for such feedback mechanisms, the current study adopts a system dynamics simulation approach to model the thermal dynamic processes in: the reactor core; the secondary coolant system; and the pressurized water reactor. The reactor core and secondary coolant system parameters used to develop system dynamics models are based on those of the Palo Verde Nuclear Generating Station. These three system dynamics models are subsequently validated, using results from published work, under different system perturbations including the change in reactivity, the steam valve coefficient, the primary coolant flow, and others. Moving forward, the developed system dynamics models can be integrated with other interacting processes within a NPP to form the basis of a dynamic system-level (systemic) risk assessment tool.

• Analytical Science and Technology
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• v.37 no.2
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• pp.123-129
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• 2024

We present a rapid method for the determination of Cs, Sr, and Ba, heat generators found in highly active liquid wastes, by gas-pressurized extraction chromatography (GPEC) using a column containing a cation-exchange resin. GPEC is a microscale column chromatographic technique that uses a constant flow rate of solvent (0.07 mL/min) with pressurized nitrogen gas supplied through a valve. In particular, because this method uses a small sample volume (a few hundred microliters), it produces less chemical waste and allows for faster separation compared to traditional column chromatography. In this study, we evaluated the separation of Cs, Sr, and Ba using GPEC. The eluate from the column (GPEC or conventional column chromatography) was quantitatively analyzed using inductively coupled plasma-mass spectrometry to measure the column recovery and precision. The column reproducibility of the proposed GPEC system (RSDs of recoveries) ranged from 2.7 to 4.1 %, and the column recoveries for the three elements ranged from 72 to 98% when aqueous HCl was used as the eluent. The GPEC results are slightly different in efficiency and separation resolution compared to those of conventional column chromatography because of the differences in the eluent flow rate as well as the internal diameter and length of the column. However, the two methods had similar recoveries for Cs and Sr, and the precision of GPEC was improved by two-fold. Remarkably, the solvent volume required for GPEC analysis was five times lower than that of the conventional method, and the total analysis time was 11 times shorter.

• Journal of Hydrogen and New Energy
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• v.35 no.3
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• pp.280-289
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• 2024

In this study, a cryogenic vessel was constructed to maintain and control the safe pressure of liquid hydrogen boil-off gas (BOG), and the numerical analysis was conducted on the development of computational fluid dynamics model inside the high-pressure vessel. An evaluation system was constructed using cryogenic inner and outer containers, pre-cooler, upper flange, and internal high-pressure container. We attempted to analyze the performance of the safety valve by injecting relatively high temperature hydrogen gas to generate BOG gas and quickly control the pressure of the high-pressure vessel up to 10 bar. As a results, the liquid volume fraction decreased with a rapid evaporation, and the pressure distribution increased monotonically inside a high pressure vessel. Additionally, it was found that the time to reach 10 bar was greatly affected by the filling rate of liquid hydrogen.

• Journal of Veterinary Clinics
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• v.29 no.4
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• pp.271-276
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• 2012

In humans, N-terminal pro-B-type natriuretic peptide (NT-proBNP) was shown to be inversely related to obesity; in addition, its association with contributing factors for obesity such as insulin, lipids, and glucose profiles has been demonstrated in the literature. However, this association between NT-proBNP and the severity of obesity has not been investigated in veterinary medicine. Our study hypothesis is that plasma levels of NT-proBNP may be related to body condition score (BCS) and contributing factors to obesity in dogs with heart diseases. To achieve our study goal, we collected blood samples from 73 client-owned dogs of small breeds at different stages of heart failure due to chronic mitral valvular insufficiency (CMVI). Fasting glucose concentrations, lipid profiles (i.e., total triglycerides [TG], total cholesterol [TC], high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol [LDL-C]), fructosamine, insulin and NT-proBNP concentrations were measured. The insulin/glucose ratio was also determined. NT-proBNP showed not only a significant correlation with the severity of CMVI related heart failure but also an inverse relationship to body condition scores (BCS), insulin plasma levels and fructosamine concentrations. We found the presence of an inverse relationship between plasma levels of NT-proBNP and the severity of obesity. In addition, NT-proBNP was associated with lower levels of contributing factors to obesity such as fructosamine and insulin, creating a possible link between the obesity and NT-proBNP in dogs with heart disease. This is also the first report demonstrating an inverse association between obesity and NT-proBNP in dogs with heart failure.

• Journal of the Korean Vacuum Society
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• v.6 no.2
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• pp.136-142
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• 1997

An/n-GaAs(100) Schottky barrier diode has been investigated by using electoreflectance(ER). From the observed Franz-Keldysh oscillatins(FKO), the internal electric field(Ei) of the sample is $5.76\times 10^{4}$V/cm at 300 K. As the modulation voltage($V_{ac}$) IS changed, the line shape of ER signal does not change but its amplitude various linerly. For increasing forward and reverse dc bias boltage($V_{bias}$), the amplitude of ER signal decreases. The internal electric field decreased from $19.3\times 10^4\sim4.39\times10^4$V/cm as $V_{bias}$ INCREASES FROM -5.0 V TO 0.6 V. For Au/n-GaAs the valve of built-in voltage($V_{bi}$) determined from the plot of $V_{bias}$ versus $E_i^2$ is 0.70 V. This value agrees with that observed in the plot of $V_{bias}$ versus amplitude of FKO peak. In addition, the carrier concentraion(N) and potential barrier($\Phi$) of the sample at 300 K are found to be about $2.4\times 10^{16}\textrm{cm}^{-3}$ and 0.78 eV, respectively.