• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.348-348
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• 2011

Carbon nanotube (CNT) field effect transistors and sensors use CNT as a current channel, of which the resistance varies with the gate voltage or upon molecule adsorption. Since the performance of CNT devices depends very much on the CNT/metal contact resistance, the CNT/electrode contact must be stable and the contact resistance must be small. Depending on the geometry of CNT/electrode contact, it can be categorized into the end-contact, embedded-contact (top-contact), and side-contact (bottom-contact). Because of difficulties in the sample preparation, the end-contact CNT device is seldom practiced. The embedded-contact in which CNT is embedded inside the electrode is desirable due to its rigidness and the low contact resistance. Fabrication of this structure is complicated, however, because each CNT has to be located under a high-resolution microscope and then the electrode is patterned by electron beam lithography. The side-contact is done by depositing CNT electrophoretically or by precipitating on the patterned electrode. Although this contact is fragile and the contact resistance is relatively high, the side-contact by far has been widely practiced because of its simple fabrication process. Here we introduce a simple method to embed CNT inside the electrode while taking advantage of the bottom-contact process. The idea is to utilize a eutectic material as an electrode, which melts at low temperature so that CNT is not damaged while annealing to melt the electrode to embed CNT. The lowering of CNT/Au contact resistance upon annealing at mild temperature has been reported, but the electrode in these studies did not melt and CNT laid on the surface of electrode even after annealing. In our experiment, we used a eutectic Au/Al film that melts at 250$^{\circ}C$. After depositing CNT on the electrode made of an Au/Al thin film, we annealed the sample at 250$^{\circ}C$ in air to induce eutectic melting. As a result, Au-Al alloy grains formed, under which the CNT was embedded to produce a rigid and low resistance contact. The embedded CNT contact was as strong as to tolerate the ultrasonic agitation for 90 s and the current-voltage measurement indicated that the contact resistance was lowered by a factor of 4. By performing standard fabrication process on this CNT-deposited substrate to add another pair of electrodes bridged by CNT in perpendicular direction, we could fabricate a CNT cross junction. Finally, we could conclude that the eutectic alloy electrode is valid for CNT sensors by examine the detection of Au ion which is spontaneously reduced to CNT surface. The device sustatined strong washing process and maintained its detection ability.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.3
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• pp.183-196
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• 2010

Increasing human activity due to rapid economic growth and land use change alters the patterns of the Asian monsoon, which is key to crop yields in Asia. In this study, we tested the performance of regional climate model (RegCM3) by simulating important components of Indian summer monsoon, including land-ocean contrast, low level jet (LLJ), Tibetan high and upper level Easterly Jet. Three contrasting rain years (1994: excess year, 2001: normal year, 2002: deficient year) were selected and RegCM3 was integrated at 60 km horizontal resolution from April 1 to October 1 each year. The simulated fields of circulations and precipitation were validated against the observation from the NCEP/NCAR reanalysis products and Global Precipitation Climatology Centre (GPCC), respectively. The important results of RegCM3 simulations are (a) LLJ was slightly stronger and split into two branches during excess rain year over the Arabian Sea while there was no splitting during normal and deficient rain years, (b) huge anticyclone with single cell was noted during excess rain year while weak and broken into two cells in deficient rain year, (c) the simulated spatial distribution of precipitation was comparable to the corresponding observed precipitation of GPCC over large parts of India, and (d) the sensitivity experiment using NIMBUS-7 SMMR snow data indicated that precipitation was reduced mainly over the northeast and south Peninsular India with the introduction of 0.1 m of snow over the Tibetan region in April.

• Analytical Science and Technology
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• v.25 no.5
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• pp.307-312
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• 2012

To perform inhalation toxicity test by using experiment animals, we set up an analytical method to monitor didecyldimethylammonium chloride (DDAC) in aerosol nebulized into inhalation chambers by ion chromatography. DDAC was adsorbed by XAD-2 resin and analyzed with conductivity detector. Recovery of DDAC desorbed by acetonitrile from XAD adsorbent was 87.8%. The method detection limit (MDL) and the limit of quantitation (LOQ) were 2.97 ${\mu}g/m^3$ and 8.92 ${\mu}g/m^3$, respectively. Repeatability was calculated as RSD 7.8% in the range of 0~20 ${\mu}g/mL$. Time needed to analyze a sample was less than 5 minutes. Therefore, the analysis of DDAC by ion chromatography was practically useful in monitoring DDAC in inhalation chambers with rapidity and sensitivity manner to perform inhalation toxicity test using experimental animals.

• Korean Journal of Head & Neck Oncology
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• v.30 no.2
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• pp.53-61
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• 2014

Background and Objectives : Anaplastic thyroid carcinoma(ATC) is a rare but highly aggressive thyroid malignancy that is associated with an extremely poor survival despite the best multidisciplinary care. BRAF(V600E) mutation is detected in about a quarter of ATC, but unlike its high treatment response to selective BRAF inhibitor (PLX4032) in metastatic melanoma, the treatment response of ATC is reported to be low. The purpose of this study is to investigate the innate resistance mechanism responsible for this low treatment response to BRAF inhibitor and its effect on epithelial-mesenchymal transition(EMT). Materials and Methods : Two ATP cell lines, 8505C and FRO were selected and treated with PLX4032 and its drug sensitivity and effects on cell migration and EMT were examined and compared. Further investigation on the changes in signals responsible for the different treatment response to PLX4032 was carried out and the same experiment was performed on both orthotopic and ectopic xenograft mouse models. Results : FRO cell line was more sensitive to PLX4032 treatment compared to 8505C cell line. The resistance to BRAF inhibition in 8505C was due to increased expression of EGFR. Effective inhibition of both EGFR and p-AKT was achieved after dual treatment with BRAF inhibitor(PLX4032) and EGFR inhibitor(Erlotinib). Similar results were confirmed on in vivo study. Conclusion : EGFR-mediated reactivation of the PI3K/AKT pathway and MAPK pathway contributes to the relative insensitivity of BRAF(V600E) mutant ATC cells to PLX4032. Dual inhibition of BRAF and EGFR leads to sustained treatment response including cell invasiveness.

• The Korean Journal of Zoology
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• v.11 no.2
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• pp.48-54
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• 1968

Male rats of the Albino strain received methylene blue in the dose of 40mg/kg by subcutaneous injection and were subjected to total body X-irradiation, 300 roentgen, at 30 minutes after the injection. The protective effect of methylene blue against the single total body X-irradiation was studied for 24 days after X-irradiation with regard to the levels of liver glycogen, blood glucose, and electrolytes in serum. 1. Total body X-irradiation generally casued an increase in the levels of the liver glycogen and blood glucose in both methylene blue treated and control group during the entire experiment. 2. Methylene blue has been shown to delay slightly the increase of the levels of the liver glycogen and blood glucose when comparing with both groups which were given methylene blue and control saline injection before irradiation in the rats. 3. The delay in the increase in the levels of liver glycogen, in experimental group injected with methylene blue, significantly came in two phases. The first phase appeared at there days after the exposure, the second followed at eighth day. It appeared that the recovery phase was at nineteenth day. 4. During the experimental days the levels of the blood glucose increased generally, methylene blue, however, caused delay in two phases; the first at fifth day, the second at eighteenth day after the exposure to X-rays. 5. In electrolytes, there was not a significant difference. The levels of chloride were, however, slightly decreased in both groups, levels of potassium appeared different in two phases at first day and twelfth day, and the levels of sodium appeared to show irregular changes at the same levels, but there was no significant difference. 6. It may be considered that methylene blue greatly reduces the sensitivity of rats to X-rays, provided that methylene blue is given before the exposure.

• The Korean Journal of Physiology
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• v.17 no.1
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• pp.45-54
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• 1983

Contractile responses of myocardium and vascular smooth muscle to angiotensin II were studied in isolated rabbit papillary muscles and aortic helical strips, with respect to the sensitivity and the mechanism of action. All experiments were performed in $HCO-_3\;-buffered Tyrode solution which was aerated with $3%\;CO_2-97%\;O_2$ and kept pH 7.35 at $35^{\circ}C$. Action potentials were measured by conventional microelectrode technique in the papillary muscles. Helical strips of vascular smooth muscle were prepared from the descending thoracic aorta of the rabbit. Angiotensin II elicited a positive inotropic effect in doses from $10^{-8}$ to $10^{-6}\;M$, and this effect was dose-dependent and characterized by a symmetrical increase of maximum dP/dt during contraction and relaxation phase. Slow responses (or slow action potentials) were induced by A. II $(10^{-6}\;M)$ in the papillary muscle hypopolarized by 27 mM $K^+$. These A. II-induced slow action potentials were eliminated by verapamil (2 mg/l), but not affected by propranolol $(10^{-5}\;M)$. In aortic helical strips, contractile force was increased dose-dependently in the range of $10^{-10}{\sim}10^{-7}\;M$ A. II. $ED_{50}$ in aorta was $3{\times}10^{-9}\;M$ A. II, whereas that in paillary muscle was $2.5{\times}10^{-7}\;M$ A. II. A. II contracted vascular smooth muscle in depolarizing concentration of $K^+$ (100 mM $K^+$), and also produced a sustained contraction even in the presence of verapamil and regitine. The results of this experiment suggest that the primarily important physiological role of A. II is the action on the blood vessel, and the positive inotropic effect of A. II in papillary muscle results from the increase of slow inward $Ca^{++}$ current, and that A. II-induced contraction of aorta is independent of transmembrane potential and associated with promoting bet transmembrane $Ca^{++}\;-influx$ and the mobilization of cellular $Ca^{++}$.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.2999-3005
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• 2009

Among the more than 120 different types of human papillomavirus (HPV), types 16 and 18 have been known to be high risk agents that cause cervical cancer. We examined, in an immuno-chromatographic analysis, the potential of using the early gene product, E7 protein, as a diagnostic marker of cervical cancer caused by HPV. We developed monoclonal antibodies specific to HPV-16 and 18 E7 proteins that were produced from bacterial cells using gene recombinant technology. For each E7 protein, the optimal antibody pair was selected using the immuno-chromatographic sandwichtype binding system based on the lateral flow through membrane pores. Under these conditions, this rapid testing assay had a detection capability as low as 2 ng/mL of E7 protein. Furthermore, since viral analysis required the host cell to be lysed using chemicals such as detergents, it was possible that the E7 protein was structurally damaged during this process, which would result in a decrease in detection sensitivity. Therefore, we examined the detrimental effects caused by different detergents on the E7 protein using HeLa cells as the host. In these experiments, we found that the damage caused by the detergent, nonylphenylpolyethylene glycol (NP-40), was minimal relative to Triton X-100 commonly used for the cell lysis. Temperature also affected the stability of the E7 protein, and we found that the E7 protein was stabilized at 4$^{\circ}C$ for about 2 h, which was 4 times longer than at room temperature. Finally, a HPV-infected cervical cancer cell line, which was used as a real sample model, was treated using the optimized conditions and the presence of E7 proteins were analyzed by immuno-chromatography. The results of this experiment demonstrated that this rapid test could specifically detect HPV-infected samples.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.1
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• pp.47-54
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• 2008

In this paper, we propose an auto-detection algorithm of basal cell carcinoma(BCC) from the protophorphyrin IX(PpIX) fluorescence image induced by appling the methyl 5-aminolaevulinate(MAL) ointment-induced protophorphyrin IX(PpIX) to the skin tumour area and then shining the wood lamp on the area. The proposed algorithm first generates 3 mask areas-tumor area, suspected tumor area and tumor free area and then applies local watershed algorithm to the turner and the suspected tumor areas to make small watershed regions that include similar luminance value pixels. Next, small watershed regions are merged by hierarchical queue based fast region merging that uses the difference between the average luminance values of adjacent watershed regions as a region merging criterion and finally BCC regions are detected. 50 tissue samples are acquired from the tumour regions of 10 patients with BCC that are extracted by using the proposed algorithm and are performed pathological examination by expert dermatologist. Experiment result shows the rate of tumor detection from BCC lesion using presurgical in vivo of MAL-indeuced PpIX fluorescence has high sensitivity 94.1% and relatively high specificity 82.6%.

• Journal of the Korea Concrete Institute
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• v.17 no.4 s.88
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• pp.581-586
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• 2005

High-performance concrete (HPC), which is particularly sensitive to self-desiccation, is required to be durable even in severe environmental conditions, i.e. costal area, cold district, etc. However, in recent years, some attention was particularly given to cracking sensitivity of high performance concrete at early age. It has been argued and demonstrated experimentally that such concrete undergoes autogenous shrinkage due to self-desiccation at early age under restrained condition, nd, as a result, internal tensile stress may develop, leading to micro cracking and macro cracking. This shrinkage-introduced crack produces a major serviceability problem for concrete structures. One possible method to reduce cracking due to autogenous shrinkage is the addition of expansive additive. Tests conducted by many researches have shown the beneficial effects of addition of expansive additive for reducing the risk of autogenous shrinkage-introduced cracking. However, the research on hydration model of expansion additive has been hardly researched up to now. This paper presents a study of the hydration model of Ettringite-Gypsum type expansive additive. As a result of comparing forecast values with experiment value, proposed model is shown to expressible of hydration of expansive additive.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.5
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• pp.606-611
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• 2009

Performance test was carried out between selective media which are generally used in Staphylococcus aureus isolation from food. Sensitivity, determined according to the appearance of characteristic colonies when 30 different S. aureus strains were tested, resulted as Baird-Parker agar (RPF)> $Petrifilm^{TM}$ Staph Express plate> Baird-Parker agar> Mannitol salt agar. Also, the four different media showed the same selectivity because all tested media did not produce the false positive colonies. Recovery efficiency from the artificially inoculated foodstuff was almost the same for the tested media. Presumptive colonies were collected from the dried fishery product using Mannitol salt agar and collected strains were tested on 4 different selective agar. Almost presumptive strains did not show the false positive colonies except for S. carnosus ssp carnosus. This strain was identified as false positive colonies on Mannitol salt agar, Baird-Parker agar and $Petrifilm^{TM}$ Staph Express plate. But Baird-Parker agar (RPF) did not show the false positive colonies with the same strains. So, it was concluded that the Baird-Parker agar (RPF) has more higher selectivity than other tested media in this experiment.