• Journal of The Korean Astronomical Society
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• v.55 no.2
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• pp.23-36
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• 2022

We present a method to determine nitrogen abundance ratios with respect to iron ([N/Fe]) from molecular CN-band features observed in low-resolution (R ~ 2000) stellar spectra obtained by the Sloan Digital Sky Survey (SDSS) and the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). Various tests are carried out to check the systematic and random errors of our technique, and the impact of signal-to-noise (S/N) ratios of stellar spectra on the determined [N/Fe]. We find that the uncertainty of our derived [N/Fe] is less than 0.3 dex for S/N ratios larger than 10 in the ranges T_eff = [4000, 6000] K, log g = [0.0, 3.5], [Fe/H] = [-3.0, 0.0], [C/Fe] = [-1.0, +4.5], and [N/Fe] = [-1.0, +4.5], the parameter space that we are interested in to identify N-enhanced stars in the Galactic halo. A star-by-star comparison with a sample of stars with [N/Fe] estimates available from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) also suggests a similar level of uncertainty in our measured [N/Fe], after removing its systematic error. Based on these results, we conclude that our method is able to reproduce [N/Fe] from low-resolution spectroscopic data, with an uncertainty sufficiently small to discover N-rich stars that presumably originated from disrupted Galactic globular clusters.

• Journal of Pharmaceutical Investigation
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• v.36 no.1
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• pp.23-29
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• 2006

A rapid, selective and sensitive reversed-phase HPLC method for the determination of promethazine in human serum was developed, validated, and applied to the pharmacokinetic study of promethazine. Promethazine and internal standard, chlorpromazine, were extracted from human serum by liquid-liquid extraction with n-hexane containing 0.8% isopropanol and analyzed on a Capcell Pak CN column with the mobile phase of acetonitrile-0.2 M potassium dihydrogen phosphate (42:58, v/v, adjusted to pH 6.0 with 1 M NaOH). Detection wavelength of 251 nm and flow rate of 0.9 mL/min were fixed for the study. The assay robustness for the changes of mobile phase pH, organic solvent content, and flow rate was confirmed by $3^{3}$ factorial design using a fixed promethazine concentration (10 ng/mL) with respect to its peak area and retention time. In addition, the ruggedness of this method was investigated at three different laboratories using same quality control (QC) samples. This method showed linear response over the concentration range of 1-40 ng/mL with correlation coefficients greater than 0.999. The lower limit of quantification using 1 mL of serum was 1 ng/mL, which was sensitive enough for pharmacokinetic studies. The overall accuracy of the quality control samples ranged from 96.15 to 105.40% for promethazine with overall precision (% C.V.) being 6.70-11.22%. The relative mean recovery of promethazine for human serum was 63.54%. Stability (freeze-thaw and short-term) studies showed that promethazine was stable during storage, or during the assay procedure in human serum. However, the storage at $-80^{\circ}C$ for 4 weeks showed that promethazine was not stable. Extracted serum sample and stock solution were not allowed to stand at ambient temperature for 12 hr prior to injection. The peak area and retention time of promethazine were not significantly affected by the changes of mobile phase pH, organic solvent content, and flow rate under the conditions studied. This method showed good ruggedness (within 15% C.V.) and was successfully used for the analysis of promethazine in human serum samples for the pharmacokinetic studies of orally administered Himazin tablet (25 mg as promethazine hydrochloride) at three different laboratories, demonstrating the suitability of the method.

• Journal of Life Science
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• v.17 no.2 s.82
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• pp.266-271
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• 2007

Bisphenol A (BPA) has been widely used as a monomer for production of epoxy resins and polycarbonate plastics. The annual production of BPA exceeds 640,000 metric tons in worldwide. BPA, a suspected phenolic endocrine disrupter, is moderately soluble and frequently detected in industrial wastewater. To date, HPLC and GC has been used for BPA analysis. However, HPLC and GC-analysis need high operation lost, experts, and an elaborate pre-treatment of samples, and is difficult to apply on-time and mass analysis. Therefore, simple, mass and rapid detection of BPA in environments is necessary. In the present study, spectrophotometric method of BPA quantification was developed. Based on blue-color product formation with BPA and ferric chloride/ferricyanide under the optimized conditions, the standard curve was acquired $({\lambda}_{750}=0.061\;BPA\;[{\mu}M]+0.07155,\;R^2=0.992)$. Using an established method, the BPA contents in the soil extract, and different water samples and living products, including disposable syringe, cup and plastic tube, were analyzed. The results suggested that the method is useful for BPA determination from different massive samples. Since the BPA metabolites, nontoxic 4-hydroxyacetophenone or 4-hydroxybenzaldehyde, did not form blue-color product, this method is also useful to screen a microorganism for BPA bioremediation.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.1
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• pp.99-108
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• 2012

In this paper, fatigue tests are conducted for the specimens with longitudinal and transverse attachment under variable amplitude axial loading based on storm model. Considered loadings include repeated single storm, 6 or 8 storms randomly, and storms including calm sea condition while the mean stress and the maximum stress of loadings are changed. The effect of three variables are investigated; root mean square(RMS) value of stress amplitude, mean stress shift and maximum stress, which can characterize storm loading on fatigue life. In addition, experiments including calm sea loading are also carried out to investigate the effect of calm sea state. Test results are evaluated and compared with DNV-CN2005 and Matsuoka's method for the estimation of crack initiation and propagation life. To verify the validity of the criteria, the measured crack initiation lifes are compared with the specific crack length 15mm, which are calculated with beach marks.

• Spatial Information Research
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• v.8 no.2
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• pp.257-274
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• 2000

Recently, natural environment is being forced by the quick increasing of population and industrialization, and especially, capacity and pollution of water resource is being come to the front. It needs to extract the accurate topological and hydrological parameters of watershed in order to manage water resource efficiently. But, these data are processed yet by manual work and simple operation in hydrological fields. In this paper, we presented algorithm that could extract topological any hydrological parameters over Sumjin watershed using GIS and RS and it gives the saving of data processing time and the confidency of data. The extraction procedure of topological characteristics and hydrological parameters is as below. First, watershed and stream are extracted by DEM and curve number is extracted throughout the overlay of landcov map and soil map. Also, we extracted surface parameters like watershed length and the slope of watershed length by Grid computation into watershed and stream. And we gave the method that could extract hydrologic parameters like Muskingum K and sub-basin lag time by executing computation into surface parameters and average SCS curve number being extracted.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1783-1790
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• 2013

A simultaneous analytical method has been developed for the fluorimetric determination of haloacetonitriles (HANs) [dichloroacetonitrile (DCAN), trichloroacetonitrile (TCAN), dibromoacetonitrile (DBAN), haloacetamides [dichloroacetamide (DCAD), and trichloroacetamde (TCAD)] in drinking water by using the combined on-line perconcentration/reversed phase liquid chromatography (RPLC)-postcolumn detection system. This on-line perconcentration system was achieved by employing a precolumn packed with a commercial solid phase extraction (SPE) sorbent for the enrichment and purification of the target analytes. The haloacetonitriles and haloacetamides were separated on CN analytical column in a 7.5% methanol-0.02 M phosphate buffered mobile phase at pH 3. The column effluents were reacted with postcolumn reagents of ophthaldialdehyde (OPA) and sulfite ion at pH 11.5, to produce a highly fluorescent isoindole fluorophore, which were measured with a fluorescence detector. Under the optimized conditions for RPLC and the postcolumn derivatization system all of the coefficient of determination of the standard calibration curves for the target analytes were over 0.99 and had a linear range from 5 to 100 ${\mu}g/L$. The detection limits showed 1.6 ${\mu}g/L$ for DCAD, 0.1 ${\mu}g/L$ for TCAD, 0.6 ${\mu}g/L$ for DCAN, 1.6 ${\mu}g/L$ for TCAN and 1 ${\mu}g/L$ for DBAN, and the recoveries were ranged from 64 to 99% except for DCAD with precisions less than 4.9% in distilled water, and from 72(${\pm}4%$) to 116%(${\pm}2%$) in tap water.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.226-226
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• 2016

PHOLED devices which have the structure of ITO/HAT-CN(5nm)/NPB(50nm)/EML(30nm)/TPBi(10nm)/Alq3(20nm)/LiF(0.8nm)/Al(100nm) are fabricated to investigate the green emission profile in EML by using a gasket doping method. CBP and Ir(ppy)3 (2% wt) are co-deposited homogeneously as a background material of EML for green PHOLED, then a 5nm thickness of additionally doped layer by Ir(btp)2 (8% wt) is formed as a profiler of the green emission. The total thickness of the EML is maintained at 30nm while the distance of the profiler from the HTL/EML interface side (x) is changed in 5nm steps from 0nm to 25nm. As shown in Fig. 1, the green (513nm) peak from Ir(ppy)3 is not observed when Ir(btp)2 is also doped homogeneously because Ir(ppy)3 works as an gasket dopant of the Ir(btp)2 :CBP system. Therefore, in this experment, Ir(btp)2 can be used as a profiler of the green emission in CBP:Ir(ppy)3 system. The emission spectra from the PHOLED devices with different x are shown in Fig. 2. In this gasket doping system, stronger red peak means more energy transfer from green to red dopant or higher exciton density by green dopant. To find the green emission profile, the external quantum efficiency (EQE) at 3mA/cm2 for red peaks are calculated. More green light emission at near EML/HBL interface than that of HTL/EML is observed (insert of Fig. 2). This means that the higher exciton density at near EML/HBL interface in homogeneously doped CBP with Ir(ppy)3. As shown in Fig. 3, excitons can be quenched easily to HTL(NPB) because the T1 level of HTL(2.5eV) is relatively lower than that of EML(2.6eV). On the other hand, the T1 level of HBL(2.7eV) is higher than that of EML.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.225-225
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• 2016

PHOLED devices which have the structure of ITO/HAT-CN(5nm)/NPB(50nm)/EML(47nm)/TPBi(10nm)/Alq3(20nm)/LiF(0.8nm)/Al(100nm) are fabricated to investigate the diffusion length of the triplet exciton by using double-quantum-well(DQE) EML structure. To fabricate DQW structures, Ir(ppy)3(2% wt) and Ir(btp)2(8% wt) are used as green and red emission zones, respectively. In DQW structured EML, as shown in Fig. 1, 1nm thick layers of green and red emission zones are located middle of the EML, and the distance between these wells(x) is changed from 0nm to 10nm. As shown in Fig. 2, the emission spectra from DQW PHOLED devices are changed with different x. The intensity of the green emission(520nm) is decreased when x is decreased, and it goes to near zero when x=0nm. This behavior can be identified as the diffusion of the triplet excitons from Ir(ppy)3 to Ir(btp)2 by the Dexter energy transfer(DET). From the external quantum efficiency(EQE) of the red emission, as shown in Fig. 3, the diffusion length of the triplet excitons can be determined by the equation of DET rate, R=A Exp(-2RDA/L), where RDA is donor-acceptor distance and L is the sum of the van der Wals radii. As a result, the measured data of the red EQEs with different x are identified to theoretical result from the equation of DET rate(Fig. 4). From this results, we could confirm that the diffusion length of the triplet excitons can be determined by using DQW structure and this method is very useful to investigate the behavior of the excitons in PHOLEDs.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.1
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• pp.16-22
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• 2017

In this paper, we first introduce a mobile data traffic offload method called Local IP Access (LIPA) with femtocell networks. Then, we evaluate the traffic transmission time and probability of mobile data traffic that is transmitted to the core network (CN) when mobile devices transmit the mobile data traffic to indoor devices in three different scenarios, i.e., conventional systems, femtocell based systems, and femtocell and LIPA based systems. Through performance results, it is shown that the next generation mobile network with the femtocell and LIPA not only decrease the density of the mobile data traffic in CNs but also reduce the total transmission time of the mobile data traffic in indoor environments. That is, for the traffic transmission time, the conventional systems and femtocell based systems have 3 and 4 times higher than the femtocell and LIPA based systems, respectively, when the Internet delay is 10ms while 14 and 26 times higher than that, respectively, when the Internet delay is 100ms.

• Journal of the Korean Chemical Society
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• v.43 no.1
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• pp.85-91
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• 1999

The second order rate constants for the hydrolysis of substituted phenyl N,N-diethyl-P-benzylphosphonamidates (2,4-$(NO_2)_2$, 4-$NO_2$, 4-CN, 4-Cl, 4-H)in 20% dioxane-water (v/v) have been determined by UV/Vis spectrophotometric method at various temperatures. The activation parameters (Ea, ${\Delta}H^{\neq}$,${\Delta}S^{\neq}$) were calculated from the rate constants and the reaction constant ($\rho$) was also estimated by Hammett equation. The activation entropies of the title reactions show considerably negative values, this result is not consistent with a dissociative mechanism (EA) in which a positive or a slightly negative value of the entropy of activation should be expected. Further, kinetic evidence for an associative mechanism (AE) was obtained from the linear free energy relationship. By the results of kinetic study for the alkaline hydrolysis of substituted phenyl N,N-diethyl-P-benzylphosphonamidates, it may be concluded that these reactions proceed through an associative mechanism.