• Macromolecular Research
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• v.16 no.6
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• pp.555-560
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• 2008

A series of hydroxyl-group containing polyimides (HPIs) were prepared in order to investigate the structure-gas permeation property relationship. Each polymer membrane had structural characteristics that varied according to the dianhydride monomers. The imidization processes were monitored using spectroscopic and thermog-ravimetric analyses. The single gas permeability of He, $H_2$, $CO_2$, $O_2$, $N_2$ and $CH_4$ were measured and compared in order to determine the effect of the polymer structure and functional -OH groups on the gas transport properties. Surprisingly, the ideal selectivity of $CO_2/CH_4$ and $H_2/CH_4$ increased with increasing level of -OH incorporation, which affected the diffusion of $H_2$ or the solubility of $CO_2$ in HPIs. For $H_2/CH_4$ separation, the difference in the diffusion coefficients of $H_2$ and $CH_4$ was the main factor for improving the performance without showing any changes in the solubility coefficients. However, the solubility coefficient of $CO_2$ in the HPIs increased at least four fold compared with the conventional polyimide membranes depending on the polymer structures. Based on these results, the polymer membranes modified with -OH groups in the polymer backbone showed favorable gas permeation and separation performance.

• Mass Spectrometry Letters
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• v.9 no.4
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• pp.95-99
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• 2018

An innovative, simple, and rapid assay method based on liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was developed and validated for the simultaneous determination of eight statin drugs in human urine. A simple sample clean-up procedure using the "dilute and shoot" (DAS) approach enabled a fast and reliable analysis. The influence of the dilution factor was investigated to ensure detectability and reduce the matrix effect. Chromatographic separation was performed on a Phenomenex Kinetex C18 column ($50{\times}3.0mm$ i.d., $2.6{\mu}m$) using an elution gradient of mobile phase A composed of 0.1% acetic acid, and mobile phase B composed of acetonitrile, at a flow rate of 0.35 mL/min. Quantitation was performed on a triple quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode using electrospray ionization in positive ion mode. The total chromatographic run time was 15 min. The method was validated for selectivity, sensitivity, recovery, linearity, accuracy, precision, and stability. The present method was successfully applied to the analysis of Rosuvastatin in urine samples after oral administration to healthy human subjects.

• Membrane and Water Treatment
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• v.10 no.5
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• pp.353-360
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• 2019

ZSM-5 membrane was prepared on tubular macroporous ${\alpha}$-alumina support using a different synthesis route. The effects of organic template agent and Si/Al ratio of the synthesis gel on morphology, structure, and separation performance of the ZSM-5 membrane used for dehydration of isopropanol were investigated. High water perm-selectivity ZSM-5 membrane with a thickness of about $3.0{\mu}m$ and a low Si/Al ratio of 10.1 was successfully prepared from organotemplate-free synthesis gel with a molar composition of $SiO_2$ : $0.050Al_2O_3$ : $0.21Na_2O$ : NaF : $51.6H_2O$ at $175^{\circ}C$ for 24 h. The ZSM-5 membrane exhibited high pervaporation performance with a flux of $3.92kg/(m^2{\cdot}h)$ and corresponding separation factor of higher than 10,000 for dehydration of 90 wt.% isopropanol/water mixture at $75^{\circ}C$.

• Journal of Life Science
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• v.20 no.12
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• pp.1784-1791
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• 2010

In this study, we investigated the effects of ethyl alcohol extracts of Hizikia fusiforme (EHF) on the correlation between tightening of tight junctions (TJs) and anti-invasive activity in human gastric adenocarcinoma AGS cells. Inhibitory effects of EHF on cell proliferation, motility, and invasiveness were found to be associated with increased tightness of the TJs, which was demonstrated by an increase in transepithelial electrical resistance. Activities of matrix metalloprotease (MMP)-2 and -9 in AGS cells were dose-dependently inhibited by treatment with EHF, and this was also correlated with a decrease in expression of their mRNA and proteins; however, tissue inhibitor of metalloproteinase (TIMP)-1 and -2 mRNA levels were increased. Additionally, immunoblotting results indicated that EHF repressed the levels of claudin proteins (claudin-1, -3, and -4), major components of TJs that play key roles in control and selectivity of paracellular transport. Furthermore, EHF decreased expression of insulin such as growth factor-1 receptor proteins, while concurrently increasing that of thrombospondin-1 and E-cadherin. In conclusion, these results suggest that EHF treatment may inhibit tumor cell motility and invasion, and therefore act as a dietary source to decrease the risk of cancer metastasis.

• Journal of radiological science and technology
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• v.17 no.1
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• pp.55-63
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• 1994

We have conducted on experiment with a purpose to evaluate the performance of grids being used at hospitals in Seoul and adjacent cities of Seoul. The results are as follows; Reality of the grids use 1. The focused grids were 105 and the parallel grids were 6 among 111 grids subject to experimenting. 2. The grid interspace material was aluminium of 94 and the remains were wood and bakelite. 3. The umber of Korean products from five companies was 33 and the one of the foreign products was 34 from companies. The physical properties have been examined by the notice of Department of Health and Social Affairs. 4. The intensity of secondary radiation was the highest in 5 : 1 grid ratio. 5. The Bucky factor increased with the increase of grid ratio. The selectivity, the grid improvement factor of grids also increased with increase of the grid ratio. However, with 6 : 1 grid ratio those factors were decreased exceptionally. In measurement of grid density with screen determiners and the beam alignment. 6. In evaluation the results were satifisfied within, 20%. 7. The value of the scale and the value of measurement were within the range of standard deviation, but the value of 103 lines were outranged from the standard deviation with all grid ratio except of 6 : 1 grid ratio.

• Journal of the Ergonomics Society of Korea
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• v.32 no.6
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• pp.535-540
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• 2013

Objective: The aim of this study is to evaluate the effectiveness and efficiency of causal links between various error causes in human error analysis. Background: As finding root causes of human error in safety-critical systems is often a cognitively demanding and time-consuming task, it is particularly necessary to develop a method for improving both the quality and efficiency of the task. Although a few methods such as CREAM have suggested causal linking between error causes as a means to enhance the quality and efficiency of human error analysis, no published research to date has evaluated the performance of the causal links. Method: The performance of the CREAM links between error causes were evaluated with 80 railway accident investigation reports from the UK. From each report, errorneous actions of operators were derived, and for each error, candidate causes were found by following the predefined links. Two measures, coverage and selectivity, were used to evaluate the effectiveness and efficiency of the links, respectively. Results: On average, 96% of error causes actually included in the accident reports were found by following the causal links, and among the total of 121 possible error causes, the number of error causes to be examined further was reduced to one-tenth on average. As an additional result of this work, frequent error causes and frequently used links are provided. Conclusion: This result implies that the predefined causal links between error causes can significantly reduce the time and effort required to find the multiple levels of error causes and their causal relations without losing the quality of the results. Application: The CREAM links can be applied to human error analysis in any industry with minor modifications.

• Biomolecules & Therapeutics
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• v.27 no.1
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• pp.117-125
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• 2019

Mebendazole (MBZ), a microtubule depolymerizing drug commonly used for the treatment of helminthic infections, has recently been noted as a repositioning candidate for angiogenesis inhibition and cancer therapy. However, the definite anti-angiogenic mechanism of MBZ remains unclear. In this study, we explored the inhibitory mechanism of MBZ in endothelial cells (ECs) and developed a novel strategy to improve its anti-angiogenic therapy. Treatment of ECs with MBZ led to inhibition of EC proliferation in a dose-dependent manner in several culture conditions in the presence of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) or FBS, without selectivity of growth factors, although MBZ is known to inhibit VEGF receptor 2 kinase. Furthermore, MBZ inhibited EC migration and tube formation induced by either VEGF or bFGF. However, unexpectedly, treatment of MBZ did not affect FAK and ERK1/2 phosphorylation induced by these factors. Treatment with MBZ induced shrinking of ECs and caused G2-M arrest and apoptosis with an increased Sub-G1 fraction. In addition, increased levels of nuclear fragmentation, p53 expression, and active form of caspase 3 were observed. The marked induction of autophagy by MBZ was also noted. Interestingly, inhibition of autophagy through knocking down of Beclin1 or ATG5/7, or treatment with autophagy inhibitors such as 3-methyladenine and chloroquine resulted in marked enhancement of anti-proliferative and pro-apoptotic effects of MBZ in ECs. Consequently, we suggest that MBZ induces autophagy in ECs and that protective autophagy can be a novel target for enhancing the anti-angiogenic efficacy of MBZ in cancer treatment.

• Membrane Journal
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• v.32 no.1
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• pp.74-82
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• 2022

The objective of this work was to investigate the gas permeation properties of CO₂ and CH₄ for PEBAX^®/TS-530 hybrid membranes and compare with pure PEBAX^®-1657 membrane. With FTIR and XRD it was possible to confirm that TS-530 was dispersed well in PEBAX^® matrix. Compared with pure PEBAX^® membrane, ideal separation factor for PEBAX^®/TS-530 (10 wt%) hybrid membrane was enhanced a little. As the amount of TS-530 was increased, the gas permeability coefficients of both CO₂ and CH₄ were increased, while the ideal separation factor was decreased. This results were explained by the reduction of crystallinity of polyamide block and interchain distance caused by introduction of inorganic nanoparticles. And fumed silica might tend to agglomerate, resulting in forming nonselective nanogaps in the hybrid materials, thus the diffusivity would be enhanced at the expense of diffusivity selectivity.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.11
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• pp.89-94
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• 2008

In this paper, a cascade of a wideband amplifier and a high-Q bandpass filter (BPF) has been realized in a 0.18mm CMOS technology for the applications of subsampling direct-conversion receivers. The wideband amplifier is designed to obtain the -3dB bandwidth of 5.4GHz, and the high-Q BPF is designed to select a 2.4GHz RF signal for the Bluetooth specifications. The measured results demonstrate 18.8dB power gain at 2.34GHz with 31MHz bandwidth, corresponding to the quality factor of 75. Also, it shows the noise figure (NF) of 8.6dB, and the broadband input matching (S11) of less than -12dB within the bandwidth. The whole chip dissipates 64.8mW from a single 1.8V supply and occupies the area of $1.0{\times}1.0mm2$.

• Korean Journal of Medicinal Crop Science
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• v.12 no.4
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• pp.304-308
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• 2004

Immune enhancing activities of water and ethanol extracts of Hypericum perforatum L. (HP) were examined. HP extracts inhibited the growth of human hepatocarcinoma, human gastric cancer cell and human breast cancer cells in concentration-dependent mammers over a concentration range of $0.05{\sim}1.0\;mg/ml$, showing inhibiton of more than 80% with the concentration of 1.0 mg/ml. However, HP the same concentration. Overall selectivity of the extracts on the three human cancer lines was over 3.5, which is higher than those from the conventional herbs. The growth of human immune B and T cells was enhanced up to 1.4 to 2.0 folds by the addition of the extracts for 4 days, compared to controls. Ethanol extracts of HP after 6 days incubation increased the secretions of tumor necrosis factor-alpha $(TNF-{\alpha})$ from T cells and interleukin-6 (IL-6) from B cells to 6.7 pg/cell and 6.8 pg/cell, respectively. These results suggest that HP has a potent immune enhancing effect.