• Journal of Biosystems Engineering
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• v.33 no.6
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• pp.404-409
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• 2008

Excessive presence of heavy metals in environment affects plants and fruits grown in the contaminated area. Rapid on-site monitoring of heavy metals can provide useful information for efficiently characterizing heavy metal-contaminated sites and for minimizing the exposure of the contaminated food crops to humans. This study reports on the evaluation of gold and glassy carbon (GC) electrodes with mercury or bismuth as a coating material for simultaneous determination of cadmium (Cd) and lead (Pb) in 0.1 M $HNO_3$ solution by anodic stripping voltammetry (ASV). The use of a square-wave voltammetric potential between a working electrode and a reference electrode caused Cd and Pb ions deposited on the electrode surface to be oxidized, thereby generating electric currents at different potentials. The mercury-coated gold electrode was not sensitive enough to detect the usable range of Cd concentrations (1 to 100 ppb). The GC electrodes with mercury or bismuth displayed well-defined, sharp and separate current peaks for Cd and Pb ions when the square-wave voltammetric potentials were applied. The peak currents measured with both mercury- and bismuth- coated GC electrodes were linearly proportional to Cd and Pb concentrations in the range of 1 to 200 ppb in 0.1 M $HNO_3$ with strong linear relationships between concentration and peak current ($R^2$ > 0.95), indicating that both of Cd and Pb ions could be quantitatively measured.

• Korean Journal of Materials Research
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• v.24 no.10
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• pp.565-571
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• 2014

Nitrogen-doped ZnO nanoparticle-carbon nanofiber composites were prepared using electrospinning. As the relative amounts of N-doped ZnO nanoparticles in the composites were controlled to levels of 3.4, 9.6, and 13.8 wt%, the morphological, structural, and chemical properties of the composites were characterized by means of field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). In particular, the carbon nanofiber composites containing 13.8 wt% N-doped ZnO nanoparticles exhibited superior catalytic properties, making them suitable for use as counter electrodes in dye-sensitized solar cells (DSSCs). This result can be attributed to the enhanced surface roughness of the composites, which offers sites for $I_3{^-}$ ion reductions and the formation of Zn3N2 phases that facilitate electron transfer. Therefore, DSSCs fabricated with 13.8 wt% N-doped ZnO nanoparticle-carbon nanofiber composites showed high current density ($16.3mA/cm^2$), high fill factor (57.8%), and excellent power-conversion efficiency (6.69%); at the same time, these DSSCs displayed power-conversion efficiency almost identical to that of DSSCs fabricated with a pure Pt counter electrode (6.57%).

• 보존과학연구
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• s.22
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• pp.115-132
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• 2001

No. 3 Tomb of Bogam-ri, in Naju City, Chollanam-do Province, was a site excavated and inspected from 1996 to 1998 and had a various grave forms, including jar-coffins, stone-chambers and stone-cists. Although most of the metal artifacts excavated from it were severely corroded, we could implement microstructure investigation by collecting samples from the iron axes, iron coffin-nails and iron clamps in which the metal parts were remained. The metal structures were inspected by using metallographic microscope and SEM, and fine components analysis was implemented by ICP. To examine the hardness differences in accordance with the structure distribution, we measured the hardness by structures with Vickers hardness testing machine. As a result of the metal structure inspection, most of them were pure iron, ferrite, and also pearlite, cementite and widmannstaten structures were displayed. We could confirm carbonization was formed on the surface of the iron axes-B, iron coffin-nails-B, and iron clamps-A. There was no carbonization in the rest of the artifacts, and it is not certain that whether the carbonized parts were peeled off through extreme corrosion or they were not carbonized when they were made. In the particular part of a blade, the quality of the material was strengthened through processing. Due to the processing re-grain was caused and fine grain particles were formed. As a result of the ICP component analysis, there were no addition atoms because pure irons were used as materials. In the mean time, No. 17 jar-coffin where the iron axes-A are excavated, is chronologically ordered as from the late-fourth century to the mid-fifth century, and No. 1 and No. 2 stone chambers, where the rest of the artifacts were excavated, as the early-sixth century. It was difficult to relate the periodic differences with the manufacture technique artifacts which we inspected because there were no distinct characteristics of the manufacture technique of the metal structures and it is impossible to conclude the artifacts and sites are at the same period although their periods are different.

• Journal of Advanced Navigation Technology
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• v.14 no.3
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• pp.313-320
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• 2010

Preparing for the rapidly increment of air traffic volume of the 21st century, International Civi1 Aviation Organization(ICAO) started for studying a newly developed CNS/ATM System from the 1980s and after 2010, expect that the existing aeronautical facility is overloaded because air traffic volume increase rapidly. For this reason new CNS/ATM System will be the international standard system in the future. Especially, ADS-B(Automatic Dependent Surveillance-Broadcast) as the key component of Surveillance and ATM in new CNS/ATM System provides the real-time and same air traffic information to pilots in the aircraft cockpit, air traffic controllers on the ground and surface vehicles at the same time. Information provided is displayed precisely and accurately through Multi-Function Display(MFD). We implement the MFD system being supporting for new CNS/ATM System. And we show the good performance of MFD system in labortory environment using the MIL-STD-1553B data bus.

• Journal of Korea Foundry Society
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• v.36 no.3
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• pp.81-87
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• 2016

In this study, the effect of scrap ratio on the mechanical properties of Zr alloys was studied. Oxygen content in the ingot cake increased rapidly with increasing fraction of scrap, which can be attributed to the surface oxide of scrap including small pieces of turning, chips, etc. Iron content did not increase much with the increasing addition of scrap, suggesting scrap materials was well reserved in the iron-free container. As-cast structure of Zr alloy with the scrap:sponge ratio displayed plate/or needle ${\alpha}$ phase and no appreciable change of the cast structure was observed with change of scrap fraction. The strength increases with increasing fraction of scrap, which can be attributed to the increase of oxygen content. The ductility decreased slightly with increase of scrap fraction. Dislocation-oxygen interaction is known to increase the strength at the expense of ductility. Ingot cake with intentionally added $Fe_2O_3$ exhibited the drastic decrease of the formability, even exhibited the brittle fracture behavior during rolling. The oxidation resistance, however, increased with the increase of scrap fraction because of high oxygen content, which may prevent more penetration and diffusion of oxygen into matrix.

• Korean Journal of Microbiology
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• v.49 no.2
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• pp.211-214
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• 2013

Bisphenol A (BPA) is a highly hazardous component to human since it is regarded as one of endocrine disruptors. For the analysis and/or removal of BPA, the searching for the specific ligand with a selective affinity to target BPA is required. In order to find the peptide moiety that specifically binds to BPA, the ultrasound-assisted biopanning was carried out with a phage-displayed peptide library expressing constrained heptamer. After six rounds of positive screening against BPA particles followed by the negative screening against the surface of eppendorf tube, the peptide sequence (CysLysSerLeuGluAsnSerTyrCys) with affinity to BPA was screened based on the order of frequency from the screened phage clones. To further verify the specificity of screened peptide sequence, the cross-binding affinity of the phage peptide toward BPA analogues such as Bisphenol S (BPS) and Bisphenol F (BPF) was also assessed, where the selected phage peptide showed a higher affinity to BPA over BPS and BPF.

• IMMUNE NETWORK
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• v.1 no.1
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• pp.53-60
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• 2001

Background: The human mic2 gene is a pseudoautosomal gene that encodes a cell surface antigen, CD99. High levels of CD99 constitute a tumor marker in Ewing s sarcoma (ES). We have recently demonstrated that CD99-induced apoptosis occurs only in undifferentiated ES cells, not in differentiated ES cells, raising the possibility of the involvement of CD99 in neural ontogeny. Methods: To elucidate the relations between the expression of CD99 and the differentiation of neural cells and the mechanism by which the expression of CD99 is regulated, we analyzed the differential patterns of CD99 expression in SH-SY5Y by treatment of 12-O-tetradecanoyl-13-phorbol acetate (TPA) and retinoic acid. In addition, to explore the transcriptional activity of CD 99 during neural cell differentiation, SH-SY5Y cells were transiently transfected with a CD99 promoter-driven luciferase construct, and treated with the inducers. Results: In immunoblotting and flow cytometry, the expression level of CD99 was increased on differentiated SH-SY5Y cells induced by TPA and retinoic acid. The luciferase activity was elevated by the treatment with TPA, known to mature SH-SY5Y cells toward a sympathetic neuronal lineage, whereas retinoic acid inducing a sympathetic chromaffin lineage displayed little effect. Conclusion: The result indicates that CD99 might be expressed only on cells maturing toward a neuronal lineage among differentiating primitive neuronal cells. In addition, the expression of CD99 seems to be regulated at the transcriptional level during the differentiation.

• Journal of the East Asian Society of Dietary Life
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• v.11 no.6
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• pp.479-484
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• 2001

The absorption characteristics of persimmon powder related to different drying methods and various storage temperatures was investigated. The physical properties of persimmon powder by different drying methods displayed the largest amount of porosity in the freeze-dried sample, and the smallest in hot air dried sample. Equilibrium moisture was reached in 6 days. Monolayer moisture contents were predicted to 0.09687~0.19712(freeze drying), 0.07820~0.18617(vacuum drying) and 0.07715~0.18056(hot air drying) g H2O/g solid respectively using the BET equation. BET equation for isothermal absorption curve showed over 0.95 R-square for all dried methods. Monolayer moisture contents were increased as storage temperature was incremented because water molecular movement was more active and there was a greater chance to clash with the absorption surface area.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.9
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• pp.4827-4834
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• 2012

Tumor suppressor genes have received much attention for their roles in the development of human malignancies. Gelsolin has been found to be down-regulated in several types of human cancers, including leukemias. It is, however, expressed in macrophages, which are the final differentiation derivatives for the monocytic myeloid lineage, implicating this protein in the differentiation process of such cells. In order to investigate the role of gelsolin in leukaemic cell differentiation, stable clones over-expressing ectopic gelsolin, and a control clone were established from U937 leukaemia cells. Unlike the control cells, both gelsolin-overexpressing clones displayed retarded growth, improved monocytic morphology, increased NADPH and NSE activities, and enhanced surface expression of the ${\beta}$-integrin receptor, CD11b, when compared with the parental U937 cells. Interestingly, RT-PCR and western blot analysis also revealed that gelsolin enhanced p21CIP1 mRNA and protein expression in the overexpressing clones. Moreover, transient transfection with siRNA silencing P21CIP1, but not the control siRNA, resulted in a reduction in monocytic differentiation, accompanied by an increase in proliferation. In conclusion, our work demonstrates that gelsolin, by itself, is capable of inducing monocytic differentiation in U937 leukaemia cells, most probably through p21CIP1 activation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.9
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• pp.1633-1640
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• 2016

In this paper, we propose a open-ended rectangular microstirp patch antenna with fork-shaped feeding structure. This antenna extends the effective bandwidth by transforming single or multi resonant frequency and is designed planar monopole structure with microstrip line to satisfy the WLAN bands (2.4 - 2.484, 5.15 - 5.35, 5.25-5.825 GHz). The substrate is printed in 0.8 mm thickness on an FR-4 board. A commercial 3D simulation tool was used to analyze surface current and electromagnetic field distribution in order to analyze the operation mode and reconfiguration principle of antenna. According to the lengths of individual patches, simulated reflection loss was compared to obtain optimized values. When it was designed with the optimized values, it satisfied WLAN bands (2.380 - 2.710, 4.900 - 5.950 GHz), if the switch is off, and 2.4 WLAN band (2.380 - 2.710 GHz). From the fabricated and measured results, measured results of return loss, gain and radiation patterns characteristics displayed for operating bands.