Reliability Enhancement of the Diverse Protection System Regarding Common Cause Failures

The issue of CCF （common cause failure） in digital I ＆ C （instrumentation and control） systems is of great interest because an increasing number of such systems are implemented in nuclear power plants. For the mitigation of ATWS （anticipated transients without scram） as well as CCF within the PPS （plant protection system） and the ESF-CCS （engineered safety feature-component control system）, the ADPS （advanced diverse protection system） has been developed by KEPCO E ＆ C （KEPCO Engineering and Construction） Company for new nuclear units in Korea. As compared to the DPS （diverse protection system） design of APR1400, the ADPS has a diverse safety injection function considering a LBLOCA （large break loss of coolant accident） concurrent with the CCF of the PPS and ESF-CCS. Besides the function of SIAS （safety injection actuation signal） initiation, several CCF avoidance features, such as the changes of software design classification, communication methods, equipment platform, and man-machine interfaces, are introduced to enhance the reliability of the ADPS. In addition, the ADPS has recently incorporated four redundant channels with 2-out-of-4 voting logics to enhance its fault tolerant capability. Therefore, it is expected that the ADPS can provide an enhanced reliability regarding possible CCFs in the safety-grade digital I ＆ C systems as well as the ADPS itself.     

Managerial capabilities of information technology and firm performance: role of e-procurement system type

Firms need to find a proper fit between their own information technology (IT) capabilities and IT systems in order to enhance performance. Thus, the purpose of this paper is to examine the moderating effect of certain e-procurement system types on the relationship between IT capabilities and firm performance. Moderated regression analysis is used to test for interaction effects of IT capabilities, including collaboration capability and dynamic capability, and e-procurement system types including, E-market and Extranet. Data of 142 Korean manufacturing firms are collected and used in the analysis. There is a stronger effect when relationships between IT capability and firm performance are considered with the involvement of other resource such as e-procurement system type. When e-procurement has a minimum-information sharing function and a high market-making function, collaboration capability had a greater contribution on financial performance. On the other hand, when an e-procurement system has limited search functions, the dynamic capability shows a greater contribution to financial performance. The result of this paper gives a strategic view by providing a new perspective regarding the suitability between e-procurement being used by itself and the IT capability necessary for this.     

Development of an efficient algorithm for global optimization by simplex elimination

An efficient multi-start algorithm for global optimization is developed by introducing multi-dimensional simplexes as new expression units of attraction regions. The region elimination method generally consists of making a set of eliminated regions called attraction regions, checking adjacency between the current design point and the attraction region, and quitting local optimization for the attracted design points. The efficiency of the elimination method is considerably enhanced by supplementing general simplexes and their neighborhoods to conventional units of attraction regions of points and lines. To show the effectiveness of the proposed algorithm, mathematical problems from the literature are solved and the results are compared with several well-known multi-start algorithms. The present algorithm produces the global optimum in all problems more efficiently than the variants of the multi-start method. Several types of truss, frame, and composite material structures are optimized as engineering applications. Many local optima are found and the differences among the local optima are not negligibly small. These results suggest that an efficient and reliable global optimizer is strongly required in some fields of engineering optimization.     

Physicochemical Characterization of Rutaecarpine-Loaded Microemulsion System

To develop an o/w microemulsion system containing poorly water-soluble rutaecarpine, the solubility of rutaecarpine in water, ethanol, various oils, and surfactants were investigated. Among the surfactants and oils tested, Tween 20/PEG 400 and castor oil were chosen as the surfactant system and oil phase of the microemulsion, as rutaecarpine was most soluble in them, respectively. Pseudoternary phase diagrams were constructed to obtain the concentration range of oil, surfactant, and cosurfactant for microemulsion formation, and the stability test of rutaecarpine delivered by microemulsion formation was then evaluated. Pseudoternary phase diagrams show that the areas of microemulsion appeared at those with 0–20% Smix (PEG 400/Tween80 = 60/40), 64–81% water, and 10–20% oil. The rutaecarpine (300 µg/g)-loaded microemulsion composed of 10.8% PEG 400, 7.2% Tween 80, 20% caster oil, and 72% water was physically and chemically stable for at least 6 months. Thus, the microemulsion system composed of castor oil, PEG 400, Tween 80, and water could be a stable dosage form for rutaecarpine.     

Prediction of residual stress and viscoelastic deformation of film insert molded parts

Film insert molding (FIM) has been modeled numerically to predict residual stress and viscoelastic deformation of the part. Nonisothermal three dimensional flow analysis for filling, packing, and cooling stages was carried out by using a commercial software. It was assumed that the inserted film was solid throughout the entire molding procedure although remelting could occur at the interface with the substrate. The flow analysis results, e.g., temperature, stress, and density distribution in the substrate domain, were transported to a finite element stress analysis program for viscoelastic stress analysis. Deflection of the FIM part was obtained as soon as the part was ejected from the mold by assuming isotropic elastic material. The residual stress distribution in the FIM part was acquired by removing the constraints along the boundary of the molded part. Viscoelastic deformation of the FIM part was predicted by performing viscoelastic stress analysis in order to understand long term behavior of the FIM part when exposed to room temperature. Durability of automotive and electronic parts produced by the film injection molding can be predicted by the procedure adopted in this study. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Investigation of various ionomer-coated carbon supports for direct methanol fuel cell applications

High-performance fuel cell electrodes require architectures that offer appropriate electrochemical and nanoscopic catalytic reaction zones. In this direction, ionomer (perfluoro sulfonic acid)-coated carbon supports were prepared by adopting a simple and cheap synthetic strategy to offer both electronic and protonic contacts to the catalyst particulates. Pt–Ru bimetallic anode catalysts were prepared on these modified carbon supports by a colloidal method. The role of surface area of carbon supports and the influence of ionomer content in them towards the catalytic activities of Pt–Ru catalysts has been probed by using three kinds of carbon black powders with different physical properties. Their electrocatalytic efficiencies toward methanol oxidation were scrutinized via half-cell measurements in cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Catalysts particulates dispersed on carbon supports coated with ionomer exhibited better performance than those on the plain carbon supports, owing to the reduced micropores and increased interfacial area between catalyst particles and ionomer. Plain and modified carbon (MC) supports were characterized by using FTIR, BET-PSD and TEM techniques. Physico-chemical characterizations of supported catalyst systems were done by using XRD and TEM.     

Epoxidation of Propylene with Hydrogen Peroxide Over TS-1 Catalyst Synthesized in the Presence of Polystyrene

Titanium silicalite-1 (TS-1) catalyst was synthesized in the presence of polystyrene (PS) particles (denoted as TS-1_PS catalyst) for use in the epoxidation of propylene with hydrogen peroxide. For the purpose of comparison, TS-1 catalyst was also synthesized by a conventional method (in the absence of polystyrene particles). In the epoxidation of propylene, the TS-1_PS catalyst showed a higher conversion of hydrogen peroxide and a higher selectivity for propylene oxide (PO) than the TS-1 catalyst. Consequently, the TS-1_PS catalyst showed a higher yield for PO than the TS-1 catalyst. Characterization results showed that the high catalytic performance of TS-1_PS was attributed to the enhanced hydrophobic property of the catalyst and the suppressed formation of anatase TiO₂ in the catalyst.     

Chemical composition and anti-inflammatory effects of essential oil from Farfugium japonicum flower

In this study, the chemical composition and anti-inflammatory activities of hydrodistilled essential oil from Farfugium japonicum were investigated for the first time. The chemical constituents of the essential oil were further analyzed by GC-MS and included 1-undecene (22.43%), 1-nonene (19.83%), beta-caryophyllene (12.26%), alpha-copaene (3.70%), gamma-curcumene (2.86%), germacrene D (2.69%), and 1-decene (2.08%). The effects of the essential oil on nitric oxide (NO) and prostaglandin E2 (PGE(2)) production in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages were also examined. The results indicate that the F. japonicum essential oil is an effective inhibitor of LPS-induced NO and PGE(2) production in RAW 264.7 cells. These inhibitory effects of the F. japonicum essential oil were accompanied by dose-dependent decreases in the iNOS and COX-2 mRNA expression. In order to determine whether F. japonicum essential oil can safely be applied to human skin, the cytotoxic effects of F. japonicum essential oil were determined by colorimetric MTT assays in human dermal fibroblast and keratinocyte HaCaT cells. F. japonicum essential oil exhibited low cytotoxicity at 100 mug/mL. Based on these results, we suggest that F. japonicum essential oil may be considered a potential anti-inflammatory candidate for topical application.     

Electrohydrodynamic drop-on-demand patterning in pulsed cone-jet mode at various frequencies

The patterning of a series of drops was investigated by the electrohydrodynamic printing method in the drop-on-demand fashion. A positive pulse voltage was applied to the capillary nozzle periodically to eject a pulsed liquid jet. The ejected jet was directed to the moving substrate, to which DC bias voltage was applied. High-speed imaging revealed that a Taylor cone was established at the nozzle tip during the ejection of the liquid jet, and that the jet directly struck the substrate to form a drop without the jet break-up. The frequency of drop generation can be controlled precisely, because the frequency of the pulsed voltage was almost same as the pulsating frequency of the liquid in pulsed cone-jet mode. The deposited patterns showed a series of uniformly sized drops with a regular spacing. At the pulse voltage frequency of 25 Hz, the diameter of the drops was approximately 95 μm. Using this drop-on-demand method, it is feasible to produce a variety of patterns of dots and continuous/discontinuous lines.     

Synthesis and characterization of polypyrrole rod doped with p‐toluenesulfonic acid via micelle formation

Rod‐type polypyrrole (PPY) doped with p‐toluenesulfonic acid (TSA) was synthesized by chemical oxidative polymerization via a self‐assembly process. The shape of the PPY particles is mainly determined by the ratio of TSA/pyrrole (PY) and feed rate of the oxidant. Particle of different shapes (rod, grain, and partially rod) exhibit differences in morphology, electrical properties, dispersity, and thermal properties. Wide‐angle X‐ray diffraction patterning analysis was used to investigate the mechanism of rod formation. The effect of the TSA concentration on the PPY structure was investigated using Fourier transform infrared spectroscopy. The PPY rods doped with TSA exhibited better electrical conductivity than granular PPY doped with TSA, and their dispersity and thermal stability were also higher. Self‐orientation of PPY in the micelles of TSA and high crystallinity of the rod particles led to improved thermal stability. Hence, the decomposition temperature of the polymer chain was considerably increased. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008