• Polymer(Korea)
• /
• v.34 no.5
• /
• pp.434-441
• /
• 2010

Sodium polyacrylate (PAANa) was synthesized by inverse emulsion polymerization method to absorb excess water in concrete. Liquid paraffin was used as a continuous phase. Acrylic acid (AA) was neutralized by aqueous sodium hydroxide solution (8 M). Different amount of N,N'-methylene bisacrylamide (MBA) was used as a crosslinking agent to change crosslinking density of the synthesized PAANa. The size distribution of synthesized particles was measured by particle size analyzer. Swelling ratio of crosslinked PAANa was evaluated from the equation in D. I. water, cement aqueous solution, and $Ca(OH)_2$ aqueous solution. The FTIR spectroscopy was used to characterize $Ca^{2+}$ ion interaction with PAANa. Incorporation of 1.0 wt% PAANa into cement increased compressive and flexural strength approximately 30% and 10%, respectively, compared with those of ordinary portland cement.

• Journal of Mechanical Science and Technology
• /
• v.19 no.4
• /
• pp.1044-1051
• /
• 2005

The isothermal characteristics of a rectangular parallelepiped sodium heat pipe were inves­tigated for high-temperature applications. The heat pipes was made of stainless steel of which the dimension was $140\;m\;(L)\;{\times}\;95m\;(W)\;{\times}\;46 m\;(H)$ and the thickness of the container was 5 mm. Both inner surfaces of evaporator and condenser were covered with screen meshes to help spread the liquid state working fluid. To provide additional path for the working fluid, a lattice structure covered with screen mesh wick was inserted in the heat pipe. The bottom surface of the heat pipe was heated by an electric heater and the top surface was cooled by circulating coolant. The concern in this study was to enhance the temperature uniformity at the bottom surface of the heat pipe while an uneven heat source up to 900 W was in contact. The temperature distribution over the bottom surface was monitored at more than twenty six locations. It was found that the operating performance of the sodium heat pipe was critically affected by the inner wall temperature of the condenser region where the working fluid may be changed to a solid phase unless the temperature was higher than its melting point. The maximum temperature difference across the bottom surface was observed to be $114^{\circ}C$ for 850 W thermal load and $100^{\circ}C$ coolant inlet temperature. The effects of fill charge ratio, coolant inlet temperature and operating temperature on thermal performance of heat pipe were analyzed and discussed.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.11
• /
• pp.3494-3499
• /
• 2009

The stability of omeprazole in the aqueous solutions containing loxoprofen or Sodium bicarbonate was examined at room temperature. Loxoprofen or Sodium bicarbonate (60 mg) was added to omeprazole (600 ${\mu}g$/ml) solution to check the stability profile. Then, the solution was kept at room temperature for 80 hours. The concentration was assayed at each concentration by stability-indicating High performance liquid chromatography (HPLC) method. Aliquots of the solution were withdrawn at specified time intervals and assayed by chromatographic analysis for intact omeprazole. The relation between omeprazole concentration and peak area was linear from 5 to 160 ${\mu}g$/ml. The analysis method was precise with relative standard deviation (% RSD) no greater than 3.05 %. The remaining percentage-time curves revealed that omeprazole was degraded rapidly as functions of time and temperature following pseudo first-order kinetics. In conclusion, the stability of omeprazole was significantly affected by liquid solutions mixed with alkalizer (Sodium carbonate) or the NSAIDs (loxoprofen).

• Nuclear Engineering and Technology
• /
• v.48 no.5
• /
• pp.1162-1173
• /
• 2016

In this paper, we describe a physicomathematical model of the processes that occur in a sodium circuit with a variable flow cross-section in the case of a water leak into sodium. The application area for this technique includes the possibility of analyzing consequences of this leak as applied to sodium-water steam generators in fast neutron reactors. Hydrodynamic processes that occur in sodium circuits in the event of a water leak are described within the framework of a one-dimensional thermally nonequilibrium three-component gas-liquid flow model (sodium-hydrogen-sodium hydroxide). Consideration is given to the results of a mathematical modeling of experiments involving steam injection into the sodium loop of a circulation test facility. That was done by means of the computer code in which the proposed model had been implemented.

• Analytical Science and Technology
• /
• v.30 no.3
• /
• pp.154-158
• /
• 2017

The Korean Pharmacopoeia (KP XI), British Pharmacopoeia (BP 2013) and Japanese Pharmacopoeia contain monographs for the quality control of raw fusidate sodium and its formulations using high performance liquid chromatography (HPLC). However, the assay method for the determination of fusidate sodium in commercial tablets is titration which is less specific than HPLC. In this study, we present an alternative HPLC method for quantitation of fusidate sodium in tablets. Method validation was performed to determine linearity, precision, accuracy, system suitability, and robustness. The linearity of calibration curves in the desired concentration range was high ($r^2=0.9999$), while the RSDs for intra- and inter-day precision were 0.25-0.37 % and 0.11-0.60 %, respectively. Accuracies ranged from 99.46-100.85 %. Since the system suitability, intermediate-precision and robustness of the assay were satisfactory, this method will be a valuable addition to the Korean Pharmacopoeia (KP XI).

• Transactions of the KSME C: Technology and Education
• /
• v.1 no.1
• /
• pp.83-90
• /
• 2013

The purpose of this study is to replace existing liquid chlorine with localization of on-site high (12%) sodium hypochlorite generation system. On-site high (12%) sodium hypochlorite generation system is higher the current efficiency of 38.7%, 54.6% reduction of salt consumption, and 97.3% lower rate of chlorate than on-site low (0.8%) sodium hypochlorite generation system.

• Nuclear Engineering and Technology
• /
• v.51 no.1
• /
• pp.284-292
• /
• 2019

For the continuous operation of a nuclear reactor, burnt fuel needs to be replaced with fresh fuel, where appropriate (ex-vessel) fuel handling is required. Particularly for the Sodium-cooled Fast Reactor (SFR) refueling, its process has unique challenges due to liquid sodium coolant. The ex-vessel spent fuel transportation should concern several design features such as the radiation shielding, decay-heat removal, and inert space separated from air. This paper proposes a new design optimization methodology of cask shielding to transport the spent fuel assembly in a prototype SFR for the first time. The Particle Swarm Optimization (PSO) algorithm had been applied to design trade-offs between shielding and cask weight. The cask is designed as a double-cylinder structure to block an inert sodium region from the air-cooling space. The PSO process yielded the optimum shielding thickness of 26 cm, considering the weight as well. To confirm the shielding performance, the radiation dose of spent fuel removed at its peak burnup and after 1-year cooling was calculated. Two different fuel positions located during transportation were also investigated to consider a functional disorder in a cask drive system. This study concludes the current cask design in normal operations is satisfactory in accordance with regulatory rules.

• Nuclear Engineering and Technology
• /
• v.56 no.1
• /
• pp.283-291
• /
• 2024

Sodium cooled Fast Reactors (SFR) are built with several engineered safety features and hence a severe accident such as a core melt accident is hypothetical with a probability of <10^-6/ry. However, in case of such accidents, the mixture of the molten fuel and structural materials interacts with sodium. This phenomenon is known as Molten Fuel Coolant Interaction (MFCI) and results in fragmentation of the melt due to various instabilities. The fragmented particles settle as a debris bed on the core catcher at the bottom of the reactor vessel, and continue to generate decay heat. Characteristics of the debris particles play a vital role in heat transfer from the bed and need thorough investigation. The size, shape, and physical state of the debris depend on the associated fragmentation mechanism, superheating of the melt, and sodium temperature. Experiments have been conducted by releasing simulated corium, a molten mixture of alumina and iron generated by the aluminothermy process at ~2400 ℃ into liquid sodium, to study the fragmentation phenomena. After the experiment, the fragmented debris was retrieved and the particle size distribution was determined by sieve analysis. The debris was subjected to microscopic investigation for obtaining morphological characteristics. Based on the characteristics of debris, an attempt has been made to assess of fragmentation mechanism of simulated corium in sodium.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.10
• /
• pp.3387-3390
• /
• 2012

In this research work the potentialities of microemulsion bulk liquid membrane for the selective transport of L-tryptophan (L-Trp) and L-tyrosine (L-Tyr) are investigated at 298.15 K. Reversed micelle formed by sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in dichloroethane, was used as mobile carrier to transport amino acids between a source and a receiving aqueous phase. The effects of pH, surfactant concentration and initial amino acid concentration on the extraction efficiency and transfer rate of the amino acids were studied. It is verified that for a mixture of two amino acids, L-Trp can be extracted selectively by using this type of the bulk liquid membrane with optimized condition.

• Environmental Analysis Health and Toxicology
• /
• v.16 no.3
• /
• pp.121-126
• /
• 2001

Analytical method of benzophenone (BP) in sediment and soil was developed by gas chromatography/mass selective detector/selected ion monitoring (GC/MSD/SIM). The ultrasonic extraction of US EPA (method 3550B) method and liquid-liquid extraction for sediment and soil samples were used for the analysis of BP from sediment and soil. BP was extracted with n-hexane. Organic layer was washed with 5% sodium chloride solution. 1∼2 l of the concentrated solution of organic layer was applied to GC/MSD. The retention time of BP peak was 11.10 min. Recovery (％) of BP by ultrasonication from sediment and soil samples was 96.0∼100.6％ and 40.0∼83.0％, respectively. Recovery of BP by liquid-liquid extraction was 51∼59％ in soil samples. The detection limit of BP in sediment and soil samples were determined to 0.1 ng/g.