• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.67.3-68
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• 2017

Bright rays are often observed after coronal mass ejections (CMEs) erupt. These rays are dynamical structures along which plasmas move outward. We investigated the outflows along the post-CME rays observed by the COR2 on board STEREO Behind on 2013 September 21 and 22. We tracked two CMEs, two ray tips, and seven blobs using the NAVE optical flow technique. As a result, we found that the departure times of blobs and ray tips from the optimally chosen starting height of 0.5 $R{\odot}$ coincided with the occurrence times of the corresponding recurrent small flares within 10 minutes. These small flares took place many hours after the major flares. This result supports a magnetic reconnection origin of the outward flows along the post-CME ray and the importance of magnetic islands for understanding the process of magnetic reconnection. The total energy of magnetic reconnection maintaining the outflows for 40 hr is estimated at 1.4' 1030 erg. Further investigations of plasma outflows along post-CME rays will shed much light on the physical properties of magnetic reconnection occurring in the solar corona.

• Bulletin of the Korean Chemical Society
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• v.35 no.12
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• pp.3482-3488
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• 2014

Matrix-induced mass bias and its effect on the accuracy of isotope ratio measurements have been examined for a quadrupole-based inductively coupled plasma-mass spectrometer (Q ICP-MS). Matrix-induced mass bias effect was directly proportional to % mass difference, and its magnitude varied for element and nebulizer flow rate. For a given element and conditions in a day, the effect was consistent. The isotope ratio of Cd106/Cd114 under $200{\mu}g\;g^{-1}$ U matrix deviated from the natural value significantly by 3.5%. When Cd 111 and Cd114 were used for the quantification of Cd with isotope dilution (ID) method, the average of differences between the calculated and measured concentrations was -0.034% for samples without matrix ($0.076{\mu}g\;g^{-1}$ to $0.21{\mu}g\;g^{-1}$ for the period of 6 months). However, the error was as large as 1.5% for samples with $200{\mu}g\;g^{-1}$ U. The error in ID caused by matrix could be larger when larger mass difference isotopes are used.

• YAKHAK HOEJI
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• v.36 no.3
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• pp.259-268
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• 1992

A procedure for the determination of KR-30075 and its metabolites in plasma and urine by high performance liquid chromatography is described. For the study of pharmacokinetic properties of KR-30075, a new PDE III inhibitor, the plasma concentration and urinary excretion after an oral administration of KR-30075 (4 mg/kg) in the male rat (Sprague Dawley) were determined by high performance liquid chromatography. The best extraction efficiency of KR-30075 and KR-30072 is obtained with ethyl ether adjusted to pH 4.0. Retention times of both KR-30072 and KR-30075 were within 5 min and resolution was complete at the flow rate of 1.0 ml/min. The sensitivity and specificity of this HPLC assay appears to be satisfactory for the pharmacokinetic study of KR-30075 and its metabolites. One-compartment open model with first-order absorption was applied to evaluate the pharmacokinetic parameters of KR-30075 according to Minimum AIC Estimation. $T_{max}$ was 1 hr, $C_{max}$ was $0.789{\pm}0.31\;{\mu}g/ml$ and elimination half $T_{1/2}$ was 6.31 min after oral administration of 4 mg/kg KR-30075 to male rats.

• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.287-295
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• 2020

Group method of data handling (GMDH) is considered one of the earliest deep learning methods. Deep learning gained additional interest in today's applications due to its capability to handle complex and high dimensional problems. In this study, multi-layer GMDH networks are used to perform uncertainty quantification (UQ) and sensitivity analysis (SA) of nuclear reactor simulations. GMDH is utilized as a surrogate/metamodel to replace high fidelity computer models with cheap-to-evaluate surrogate models, which facilitate UQ and SA tasks (e.g. variance decomposition, uncertainty propagation, etc.). GMDH performance is validated through two UQ applications in reactor simulations: (1) low dimensional input space (two-phase flow in a reactor channel), and (2) high dimensional space (8-group homogenized cross-sections). In both applications, GMDH networks show very good performance with small mean absolute and squared errors as well as high accuracy in capturing the target variance. GMDH is utilized afterward to perform UQ tasks such as variance decomposition through Sobol indices, and GMDH-based uncertainty propagation with large number of samples. GMDH performance is also compared to other surrogates including Gaussian processes and polynomial chaos expansions. The comparison shows that GMDH has competitive performance with the other methods for the low dimensional problem, and reliable performance for the high dimensional problem.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.662-665
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• 2002

The growth of carbon nanotubes (CNTs) was carried out using ratio frequency plasma enhanced chemical vapor deposition (rf PECVD) system equipped with dc bias for the directional growth. Acetylene and ammonia gas were used as the carbon source and a catalyst. The relation between gas flow rate and dc bias on the growth of CNTs was investigated. We studied the relation between emission properties and the directionality of CNTs grown under different dc bias voltage.

• Journal of Korean Society on Water Environment
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• v.28 no.3
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• pp.401-408
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• 2012

High-voltage dielectric discharges are an emerging technique in environmental pollutant degradation, which that are characterized by the production of hydroxyl radicals as the primary degradation species. The initiation and propagation of the electrical discharges depends on several physical, chemical, and electrical parameters such as 1st and 2nd voltage of power, gas supply, conductivity and pH. These parameters also influence the physical and chemical characteristics of the discharges, including the production of reactive species such as OH, $H_2O_2$ and $O_3$. The experimental results showed that the optimum 1st voltage and air flow rate for RNO (N-Dimethyl-4-nitrosoaniline, indicator of the generation of OH radical) degradation were 160 V (2nd voltage of is 15 kV) and 4 L/min, respectively. As the increased of the 2nd voltage (4 kV to 15 kV), RNO degradation, $H_2O_2$ and $O_3$ generation were increased. The conductivity of the solution was not influencing the RNO degradation and $H_2O_2$ and $O_3$ generation. The effects pH was not high on RNO degradation. However, the lower pH and the conductivity, the higher $H_2O_2$ and $O_3$ generation were observed.

• Journal of Korean Vacuum Science & Technology
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• v.4 no.2
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• pp.55-60
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• 2000

Vertically aligned carbon nanotubes on nickel coated glass substrates were obtained at low temperatures below 600$\^{C}$ by plasma enhanced hot filament chemical vapor deposition where acetylene gas was used as the carbon source and ammonia gas was used as the dilution gas and catalyst. The diameters of the nanotubes decreased from 96 m to 41 m as NH$_3$/C$_2$H$_2$ ratio increased from 2:1 to 5:1. Total flow rate of input gases with constant NH$_3$/C$_2$H$_2$ ratio did not change the diameter of carbon nanotubes. No growth of the carbon nanotubes was observed with only C$_2$H$_2$ nor N$_2$ instead of NH$_2$. G line and D line in Raman spectra were observed, which implies that there were many structural defects in carbon nanotubes.

• Journal of the Korean Vacuum Society
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• v.7 no.1
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• pp.43-50
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• 1998

Transparent and conducting tin oxide films were prepared on Pyrex glass substrates by the remote plasma chemical vapor deposition (RPCVD). The main control variables of the RPCVD process included the deposition time, the flow rates of tetramethyltin, oxygen and argon, the radio-frequency power, and the substrate temperature. Dependence of the deposition rate, electric resistivity, optical transmittance and crystal structure on these parameters was systematically examined to prepare high qualities of tin oxide films and to better understand RPCVD process. The effect of those parameters on the properties of tin oxide films in complicatedly related on another. A tin oxide film parameters on the protimized deposition conditions exhibited deposition rate of 102 $\AA$/min, electric resistivity of $9.7\times 10^{-3}\Omega$cm and visible transmittance of ~80%.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1555-1559
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• 1997

The thin films were obtained by plasma polymerization of phenyl isothiocyanate. Polymerizations were carried out in rf(13.56[MHz]) glow discharge generated in an inter-electrode capacitively coupled gas flow system. It was found that this monomer produces uniform films with a wide range of thicknesses, from hundreds of nanometers to tens of micrometers. The deposition rate appeared to be dependent on the substrate distance from the monomer inlet. The IR data revealed significant decrease in -NCS groups content in the polymer as compared with the monomer spectrum and indicated for the appearance of new absorption bands corresponding to the -CN and C-H aliphatic groups. The soluble fraction by GC was found to be composed of numerous low molecular-weight compounds.

• Korean Journal of Materials Research
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• v.5 no.5
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• pp.568-574
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• 1995

We investigated the effects of B-doping on the growth mechanism of ZnO films. The B-doped ZnO films, which were widely applied for transparent conducting electrode, were deposited by plasma enhanced chemcial vapor depostion(PECVD) using diethylzinc(DEZ), No.sub 2/. and B$_{2}$H$_{6}$. The deposition conditions were a sbustrate temperature of 30$0^{\circ}C$, an rf power of 200, and a chamber pressure of 1 torr. At the given depostion condition, the growth rate of B-doped ZnO thin films was higher than that of undoped ones, but didn't change even with further increasing B$_{2}$H$_{6}$ flow rate and the interplanar distance between(0002) planes was reduced as B atoms substituted Zn sites.s.