• Nuclear Engineering and Technology
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• v.48 no.5
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• pp.1192-1205
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• 2016

Field programmable gate array (FPGA)-based systems are thought to be a practical option to replace certain obsolete instrumentation and control systems in nuclear power plants. An FPGA is a type of integrated circuit, which is programmed after being manufactured. FPGAs have some advantages over other electronic technologies, such as analog circuits, microprocessors, and Programmable Logic Controllers (PLCs), for nuclear instrumentation and control, and safety system applications. However, safety-related issues for FPGA-based systems remain to be verified. Owing to this, modeling FPGA-based systems for safety assessment has now become an important point of research. One potential methodology is the dynamic flowgraph methodology (DFM). It has been used for modeling software/hardware interactions in modern control systems. In this paper, FPGA logic was analyzed using DFM. Four aspects of FPGAs are investigated: the "IEEE 1164 standard," registers (D flip-flops), configurable logic blocks, and an FPGA-based signal compensator. The ModelSim simulations confirmed that DFM was able to accurately model those four FPGA properties, proving that DFM has the potential to be used in the modeling of FPGA-based systems. Furthermore, advantages of DFM over traditional reliability analysis methods and FPGA simulators are presented, along with a discussion of potential issues with using DFM for FPGA-based system modeling.

• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.171-176
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• 2012

A novel chemiluminescence (CL) system was established for the determination of cytosine arabinoside (Ara-C) in pharmaceutical preparations. It was showed that a clear CL signal was observed when Eosin Y mixed with Fenton reagent. The CL intensity was decreased significantly when Ara-C was added to the reaction system and partially scavenged the hydroxyl radicals in the solution. The extent of decrease in the CL intensity had a good stoichiometrical relationship with the Ara-C concentration. Based on this, we developed a new method for the determination of Ara-C using a flow injection analysis (FIA) technique with CL detection. Under the optimal conditions, the linear range of Ara-C concentration was $6.0{\times}10^{-9}\sim1.0{\times}10^{-7}mol/L$ (R = 0.9982) with a detection limit of $7.6{\times}10^{-10}mol/L$ (S/N=3), the RSD was 5.6% for $6.0{\times}10^{-8}mol/L$ Ara-C (n = 11). The method was successfully applied to the determination of Ara-C in injection samples. The possible chemiluminescence reaction mechanism was discussed.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3259-3264
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• 2010

A label-free amperometric immunosensor has been proposed for the detection of myeloperoxidase (MPO) in human serum. To fabricate such an immunosensor, a composite film consisting of N,N-dimethylformamide (DMF), multiwall carbon nanotubes (MWCNTs) and 1-ethyl-3-methyl imidazolium tetrafluoroborate ($EMIMBF_4$) suspension was initially formed on a glassy carbon electrode (GCE). Then cerium dioxide ($CeO_2$) dispersed by chitosan was coated on the GCE. After that, MPO antibodies (anti-MPO) were attached onto the nano$CeO_2$ surface. With a noncompetitive immunoassay format, the antibody-antigen complex formed between the immobilized anti-MPO and MPO in sample solution. The immunosensor was characterized by cyclic voltammetry, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The factors influencing the performance of the immunosensor were studied in detail. Under optimal conditions, the current change before and after the immunoreaction was proportional to MPO concentration in the range of 5 to $300\;ng\;mL^{-1}$ with a detection limit of $0.2\;ng\;mL^{-1}$.

• Journal of the Korean Wood Science and Technology
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• v.36 no.5
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• pp.49-55
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• 2008

This study was carried to investigate the effects of steaming and four different drying methods on the longitudinal liquid permeability of Korean pine (Pinus koraiensis Sieb.et Zucc.) board. Four drying methods were air drying, conventional kiln drying, microwave-vacuum drying and high temperature drying. Darcy equation was used for calculating the specific permeability of the small sapwood specimens taken from the treated boards while capillary rising method was used for the heartwood specimens. The sapwood specimens were extracted with water and benzene-alcohol solution to examine the mechanism of liquid flow in treated wood. No significant correlation was found between specific permeability and the number of resin canals of the sapwood specimens. Extraction decreased the differences of specific permeabilities of the sapwood specimens between the five treatment methods. The effects of extraction on the longitudinal permeability are different between five treatments. The fluid path in heartwood was observed by dynamic observation method.

• ETRI Journal
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• v.34 no.3
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• pp.361-368
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• 2012

A complete high-frequency small-signal circuit model of a 40 Gb/s butterfly electroabsorption modulator integrated laser module is presented for the first time to analyze and optimize its electro-optic (E/O) response and reflection characteristics. An agreement between measured and simulated results demonstrates the accuracy and validity of the procedures. By optimizing the bonding wire length and the impedance of the coplanar waveguide transmission lines, the E/O response increases approximately 5% to 15% from 20 GHz to 33 GHz, while the signal injection efficiency increases from approximately 15% to 25% over 18 GHz to 35 GHz.

• Korean Journal of Materials Research
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• v.25 no.10
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• pp.571-576
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• 2015

The effects of coating thickness on the delamination and fracture behavior of thermal barrier coating (TBC) systems were investigated with cyclic flame thermal fatigue (FTF) and thermal shock (TS) tests. The top and bond coats of the TBCs were prepared by electron beam-physical vapor deposition and low pressure plasma spray methods, respectively, with a thickness ratio of 2:1 in the top and bond coats. The thicknesses of the top coat were 200 and $500{\mu}m$, and those of the bond coat were 100 and $250{\mu}m$. FTF tests were performed until 1140 cycles at a surface temperature of $1100^{\circ}C$ for a dwell time of 5 min. TS tests were also done until more than 50 % delamination or 1140 cycles with a dwell time of 60 min. After the FTF for 1140 cycles, the interface microstructures of each TBC exhibited a sound condition without cracking or delamination. In the TS, the TBCs of 200 and $500{\mu}m$ were fully delaminated (> 50 %) within 171 and 440 cycles, respectively. These results enabled us to control the thickness of TBC systems and to propose an efficient coating in protecting the substrate in cyclic thermal exposure environments.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.491-494
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• 2006

Kalman filtering (KF) is hard to be applied to the SINS (Strap-down Inertial Navigation System)/RDSS (Radio Determination Satellite Service) integrated navigation system directly because the time delay of RDSS positioning in active mode is random. BP (Back-Propagation) Neuron computing as a powerful technology of Artificial Neural Network (ANN), is appropriate to solve nonlinear problems such as the random time delay of RDSS without prior knowledge about the mathematical process involved. The new algorithm betakes a BP neural network (BPNN) and velocity feedback to aid KF in order to overcome the time delay of RDSS positioning. Once the BP neural network was trained and converged, the new approach will work well for SINS/RDSS integrated navigation. Dynamic vehicle experiments were performed to evaluate the performance of the system. The experiment results demonstrate that the horizontal positioning accuracy of the new approach is 40.62 m (1 ${\sigma}$), which is better than velocity-feedback-based KF. The experimental results also show that the horizontal positioning error of the navigation system is almost linear to the positioning interval of RDSS within 5 minutes. The approach and its anti-jamming analysis will be helpful to the applications of SINS/RDSS integrated systems.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.3
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• pp.220-226
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• 2000

The piezoelectric material for piezoelectric transformer needs the high electromechanical coupling factor( $k_{p}$) the piezoelectric constant( $d_{33}$) and the mechanical quality factor( $Q_{m}$)in order to obtain high voltage step-up ratio and low temperature rising. In this study the piezoelectric transformers were fabricated using Pb［$Zr_{0.45}$/ $Ti_{0}$48//L $u_{0.02}$(M $n_{1}$3//S $b_{2}$3/)$_{0.05}$］ $O_3$(PMS-PZT) and Pb［Z $r_{0.25}$/ $Ti_{0.375}$(M $g_{1}$3//N $b_{2}$3/)$_{0.375}$］ $O_3$+0.5wt%Mn $O_2$(PMN-PZT) ceramics. The piezoelectric properties of PMS-PZT and PMN-PZT were measured. The voltage set-up ratios of the piezoelectric transformers using PMS-PZT and PMN-PZT were the value of 15, 20 respectively under 100$_{KΩ}$ in Rosen type transformer.r.ormer.r.r.r.r.r.r.

• 보존과학연구
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• s.23
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• pp.5-39
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• 2002

The scientific analysis and provenance study of potteries excavated from kiln sites at Jeonla Nam. Buk-do were carried out using XRD,ICP-AES and NAA. We can summarize the following consequence. First, as a result of XRD analysis, it showed that soft potteries consist of quartz, feldspar and clay minerals while hard potteries consist of high temperature crystals such as mullite, tridymite, cristobalite. In case of firing temperature which are determined by crystals using XRD, potteries are composed of quartz, feldspar and clay minerals had very low firing temperature. While potteries having only cristobalite ranged above$1200^{\circ}C$. Second, as a result of correlation analysis using trace element, the selected characteristic elements which was able to distinguish from each kiln site was Ce, Lu, Cs, Sc, Eu. Third, discriminant analytical results showed that kiln site of the Jeonla Namdo were classified into five groups and that of the Jeolna Buk-do into three groups. This suggests that there are no correlations between the raw materials used in each kiln sites.

• Nuclear Engineering and Technology
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• v.49 no.6
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• pp.1318-1325
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• 2017

Direct Numerical Simulation (DNS) serves as an irreplaceable tool to probe the complexities of multiphase flow and identify turbulent mechanisms that elude conventional experimental measurement techniques. The insights unlocked via its careful analysis can be used to guide the formulation and development of turbulence models used in multiphase computational fluid dynamics simulations of nuclear reactor applications. Here, we perform statistical analyses of DNS bubbly flow data generated by Bolotnov ($Re_{\tau}=400$) and LueTryggvason ($Re_{\tau}=150$), examining single-point statistics of mean and turbulent liquid properties, turbulent kinetic energy budgets, and two-point correlations in space and time. Deformability of the bubble interface is shown to have a dramatic impact on the liquid turbulent stresses and energy budgets. A reduction in temporal and spatial correlations for the streamwise turbulent stress (uu) is also observed at wall-normal distances of $y^+=15$, $y/{\delta}=0.5$, and $y/{\delta}=1.0$. These observations motivate the need for adaptation of length and time scales for bubble-induced turbulence models and serve as guidelines for future analyses of DNS bubbly flow data.