• Korean Chemical Engineering Research
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• v.55 no.5
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• pp.660-667
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• 2017

Equilibrium data of the mixture is essential in the design and operation of separation equipment such as distillation or extraction in chemical processes. These equilibrium data can be obtained through experiments or by calculations using the known binary parameters and the thermodynamic models. Generally, to obtain these parameters, phase equilibrium experimental data such as gas-liquid and liquid-liquid are used. In this study, the excess enthalpy of the mixture was measured using the flow type microcalorimeter which is a simpler method than phase equilibria experiments, and the parameters of various theories were obtained by using this data. In order to investigate the relationship between carbon chain length, enthalpy and binary parameters in the alkane system, excess enthalpies for the n-hexane + alkane (n-pentane, n-heptane, n-octane and n-dodecane) were measured at 298.15 K and the banary interaction parameters of Wilson, NRTL, and UNIQUAC were obtained from the experimental data. In addition, we wanted to obtain basic information on the interaction and association phenomena of the system including electrolyte applicable to various fields by using the excess enthalpy experimental data and the existing theory. First, we investigated the excess enthalpy for the NaOH / Water / Ethanol system as a basic experiment and examined the applicability using the electrolyte-NRTL (eNRTL) theory.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.2
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• pp.113-123
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• 2005

The removal of radioactive corrosion products from the reactor coolant through a magnetic filter system is one of the many approaches being investigated as a means to reduce radiation sources and exposures to the operational and maintenance personnel in a nuclear power plant. Many research activities in water chemistry, therefore, have been performed to provide a filtration system with high reliability and feasibility and are still in process. In this study, it was devised the magnetic filter system with permanent and electric magnets to remove the corrosion products in the coolant stream taking an advantage of the magnetic properties of corrosion particles. Permanent magnets were used for separation of corrosion products and electric magnets were utilized for flocculation of colloidal particles to increase in their size. Experiments using only permanent magnets, in the previous study, displayed the satisfactory outcome of filtering corrosion products and indicated that the removal efficiency was more than 90 $\%$ for above 5 $\mu$m particles. Experiments using electric magnets also showed the good performance of flocculation without chemical agents and exhibited that most corrosion particles were flocculated into larger aggregates about 5 $\mu$m and over in diameter. It is, thus, expected that the magnetic filter system with the arrangement of permanent and electric magnets will be an effective way for the removal of radioactive corrosion products with considerably high removal efficiency.

• Land and Housing Review
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• v.12 no.4
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• pp.103-117
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• 2021

With the current rapid changes in population and technology, the long-lastig housing certification system is a means of prolonging the physical and functional lifespan of a building. The certification requires differentiation between the structure and infill elements to allow for variability and ease of repairs. This works well with prefabricated houses so this study investigated the possibility of applying the long-lastig housing certification requirements to apartment construction using off-site construction (OSC) methods focused on the installation of bathrooms (plumbing and toilet) that differ from the traditional wet method. This study examined three different sized floor plans at 22 m², 46 m², and a combined one resulting in 69 m². The larger 69 m² plan utilized a removeable non-load bearing wall to increase flexibility in the layout of the floorplan. The apartments are constructed of steel reinforced concrete composite columns on a 9 m × 10.5 m grid with integrated slabs. The exterior and interior infill walls are all non-load bearing with some containing plumbing. This separation of the structure and infill walls can help meet some of the criteria in the long-lastig housing certification, particularly with the ease of repairs. Technologies that facilitate the replacement of infill elements that contain plumbing and other building services can benefit the nation by reducing carbon emissions and therefore tax incentives should be introduced to increase the adoption of the proposed construction methods.

• The Journal of the Acoustical Society of Korea
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• v.29 no.7
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• pp.458-467
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• 2010

In this paper, a new audio reproduction system was developed in which the cross-talk signals would be reasonably cancelled at an arbitrary listener position. To adaptively remove the cross-talk signals according to the listener's position, a method of tracking the listener position was employed. This was achieved using the two microphones, where the listener direction was estimated using the time-delay between the two signals from the two microphones, respectively. Moreover, room reverberation effects were taken into consideration where linear prediction analysis was involved. To remove the cross-talk signals at the left-and right-ears, the paths between the sources and the ears were represented using the KEMAR head-related transfer functions (HRTFs) which were measured from the artificial dummy head. To evaluate the usefulness of the proposed listener tracking system, the performance of cross-talk cancellation was evaluated at the estimated listener positions. The performance was evaluated in terms of the channel separation ration (CSR), a -10 dB of CSR was experimentally achieved although the listener positions were more or less deviated. A real-time system was implemented using a floating-point digital signal processor (DSP). It was confirmed that the average errors of the listener direction was 5 degree and the subjects indicated that 80 % of the stimuli was perceived as the correct directions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.175-178
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• 2008

While read operation on flash memory is fast and doesn't have any constraints, flash memory can not be overwritten on updating data, new data are updated in new area. If data are frequently updated, garbage collection, which is achieved by erasing blocks, should be performed to reclaim new area. Hence, because the number of erase operations is limited due to characteristics of flash memory, every block should be evenly written and erased. However, if data with access locality are processed by cost benefit algorithm with separation of hot block and cold block, though the performance of processing is high, wear-leveling is not even. In this paper, we propose CB-MG (Cost Benefit between Multi Group) algorithm in which hot data are allocated in one group and cold data in another group, and in which role of hot group and cold group is exchanged every period. Experimental results show that performance and wear-leveling of CB-MG provide better results than those of CB-S.

• Membrane Journal
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• v.22 no.2
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• pp.128-134
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• 2012

In this study, hydroxy polyimide (HPI) was prepared for non-porous membrane by solvent evaporation method. As the result of gas permeance properties measurement, $CO_2$ permeability was 85 Barrer and the $CO_2/N_2$ selectivity was 23 at $30^{\circ}C$. Flat sheet membrane and hollow fiber membrane were prepared by using ternary system of polymer, solvent and non-solvent additive. Morphologies and gas permeance properties were measured by FE-SEM and bubble flow meter. Each $CO_2$ permeability of 18.28 GPU, 70 GPU and $CO_2/N_2$ selectivity of 6.72, 8.63 at $30^{\circ}C$ in the flat sheet membrane and hollow fiber membrane. Hollow fiber membrane has gas permeance property better than flat sheet membrane.

• Applied Chemistry for Engineering
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• v.4 no.3
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• pp.601-615
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• 1993

A series of polycarbonate(PC)/polyamide 6(PA6) blends were prepared by three different blending methods to investigate their compatibility. From the DSC results, all of these blends have two Tg's in their own Tg regions, and there was no significant depression of the melting point and the crystallization temperature of PA6. With respect to the microstructure of the blends by SEM, the phase separation occurred at very low blend compositions, PC/PA6=95/5 and 5/95, already. In addition, a method is proposed to determine the Flory-Huggins polymer-polymer interaction parameter(${\chi}_{12}$) in polymer blend systems by using the experimentally determined Tg's. The values of ${\chi}_{12}$ obtained were 0.0381, 0.0411, 0.0418, for solution casting, solution precipitation, and extrusion blending methods, respectively. These values were higher than the critical value of ${\chi}_{12}$,($({\chi}_{12})_c$, 0.0271). Therefore it was concluded that the PC/PA6 blend system have little compatibility.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2010.04a
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• pp.389-391
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• 2010

The Free surface influenced the wake behind a circular cylinder and its effects were investigated experimentally in a circulating water channe with the variation of water depth Instantaneous velocity fields were measured in this paper. the measured results has been compared with each other to investigate the flow characteristics of the circular cylinder's 2-dimensional section at $Re=1.0\times10^3$ using 2-frame grey level cross correlation PIV method. The flow around the circular cylinder with free surface affected the wake structure. especially, in case of d=1.0D, the boundary layer was measured in the whole area. The separation point and boundary layer of the circular cylinder could be controlled by the water depth.

• Korean Journal of Food Science and Technology
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• v.36 no.4
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• pp.558-562
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• 2004

Conditions for rapid quantification of isoflavones were studied. Rapid and clear separation of isoflavones (genistin and daidzin) was obtained using solvent system of chloroform : methanol : water : acetic acid (60 : 30 : 10 : 0.5, v/v/v/v). Quantification of each isoflavone separated by TLC was conducted by densitometry analysis. Genistin and daidzin were quantified in $0.15-1.80\;{\mu}g/{\mu}L$ range with 99% confidence. Concentrations of isoflavones in soybeans and kudzu roots originated from Korea were determined, and validity of TLC method for quantification of isoflavones was confirmed by comparison with HPLC analysis.

• Korean Journal of Pharmacognosy
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• v.47 no.4
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• pp.381-388
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• 2016

Hyangso-san is a traditional herbal medicine that consists of the seven herbal medicines, Cyperi Rhizoma, Perillae Folium, Atractylodis Rhizoma, Citri Unshius Pericarpium, Glycyrrhizae Radix et Rhizoma, Zingiberis Rhizoma Crudus, and Allii Fistulosi Bulbus. Hyangso-san has long been clinically used to treat the influenza, including headache, ferver, chills, and pantalgia. In this study, we were performed the simultaneous analysis of the 15 marker compounds (liquiritin apioside, liquiritin, ferulic acid, naringin, hesperidin, rosmarinic acid, liquiritigenin, kaempferol, glycyrrhizin, nobiletin, 6-gingerol, elemicin, atractylenolide III, nootkatone, and atractylenolide I) in Hyangso-san using liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS). Column for the separation of the 15 ingredients was used a Waters Acquity UPLC BEH $C_{18}$ analytical column ($2.1{\times}100mm$, $1.7{\mu}m$) at $45^{\circ}C$ by using a mobile phase of 0.1% (v/v) formic acid in water and acetonitrile with gradient condition. Identifications of all analytes were performed using a Waters ACQUITY TQD LC-MS/MS system. The flow rate and injection volume were 0.3 mL/min and $2.0{\mu}L$, respectively. Correlation coefficient of the calibration curve was ${\geq}0.9958$. The values of limits of detection and quantification of the 15 components were 0.002-4.29 and 0.01-12.88 ng/mL, respectively. The result of an analysis using the established LC-MS/MS method, kaempferol and atractylenolide I were not detected, while other 13 compounds were 0.08-56.87 mg/g in lyophilized Hyangso-san sample.