• Advances in nano research
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• v.13 no.6
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• pp.561-574
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• 2022

The stability of protein tissues and protein fibers in the human muscle is investigated in the presented paper. The protein fibers are modeled via tube structures embedded in others proteins fibers like the elastic substrate. Physical sport and physical exercise play an important role in the stability of synthesis and strength of the protein tissues. In physical exercise, the temperature of the body increases, and this temperature change impacts the stability of the protein tissues, which is the aim of the current study. The mathematical simulation of the protein tissues is done based on the mechanical sciences, and the protein fibers are modeled via wire structures according to the high-order theory beams. The thermal stress due to the conditions of the sport is applied to the nanoscale protein fibers, then the stability regarding the frequency analysis is investigated. Finally, the impact of temperature change, physical exercise, and small-scale parameters on the stability of the protein tissues are examined in detail.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.170-171
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• 2022

In recent years, due to the occurrence of traffic accidents caused by black ice in winter, the number of personal injuries is increasing rapidly. Black ice is a phenomenon that occurs like a thin layer of ice on the road surface. Accordingly, many developments of heat-generating concrete are being developed to remove ice by increasing the temperature by supplying constant electricity to places where black ice is likely to occur. These heating elements are being developed by mixing a conductive material represented by carbon nanotubes with concrete. However, research up to now has been focused on efficient temperature rise and derivation of the optimum mixing ratio, and the evaluation of maintaining heat generation performance during continuous repetition is insufficient. Therefore, in this study, a heating test specimen was manufactured and 50V power was repeatedly supplied to evaluate the heating characteristics.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.67-68
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• 2021

In this study, Repair mortar was prepared using CNT powder with improved dispersibility and its characteristics were analyzed. As a result of the experiment, the compressive strength and flexural strength were found to be at similar levels compared to Plain without CNT. In addition, as a result of the drying shrinkage test, it was found that the drying shrinkage amount was decreased due to the effect of CNT mixed into the porous material filling the internal pores of the repair mortar.. The Bond strength of the repair mortar was at a similar level regardless of whether CNT was added or not

• Structural Engineering and Mechanics
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• v.88 no.2
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• pp.109-115
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• 2023

In this paper, frequencies of zigzag structure of carbon nanotubes isinvestigated based on Donnell shell theory. These tubes are wrapped with the ring supports in the axial direction. The fundamental frequency curves displayed in article show the dependence of vibrations attributes to zigzag single walled carbon nanotubes. Various zigzag indices are introduced against the variation of length to predict the vibration. Also, the influence of ring supports is sketched with proposed structure for frequency analysis. The frequencies of zigzag tube decreases as the length increases. It is observed that the frequencies decreases with ring support and have higher frequencies without ring. The problem is formulated using Partial Differential Equation. Three expressions of modal deformation displacement functions is used for the elimination of temporal variation to form the solution in the eigen from. For the stability of present study the results are compared with experimentally and numerically in the open text.

• Journal of radiological science and technology
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• v.33 no.3
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• pp.179-184
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• 2010

A hard X-ray microscope system for obtaining images of nano-spatial resolution has been widely studied and requires monochromatic X-ray. A multilayer mirror of 84% reflectivity was designed to acquire tungsten characteristic X-ray of 8.4 keV from the white beam generated from an X-ray tube, and the C/W multilayer mirror of $50{\times}50\;mm$ size and 5.65 nm d-spacing was fabricated by the ion-beam sputtering system. The C/W multilayer had a uniformity of 99.5%, and the structure of the multilayer mirror was verified by a TEM image. The obtainable x-ray reflectivity for the C/W multilayer mirror at 8.4 keV was estimated from measuring the X-ray reflectivity using the copper characteristic X-ray of 8.05 keV. Monochromatic X-ray of 8.4 keV was generated by combining a X-ray tube, and the reflectivity and monochromaticity were 77.1% and 0.21 keV, respectively. Monochromatic X-ray generated from the combination of an X-ray tube and an C/W multilayer mirror has enough potential to use X-ray source for hard X-ray microscope system of laboratory size. If the C/W multilayer mirror of d-spacing of a few nanometers can be fabricated, monochromatic X-ray corresponded to 17.5 keV, molybdenum characteristic X-ray, can be obtained and applied to mammography in the medical application.

• Korean Journal of Clinical Laboratory Science
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• v.49 no.4
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• pp.323-328
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• 2017

Angiogenesis is a process including members of the angiogenic factors. In particular, fibroblast growth factor 2 (FGF2) is considered the most potent angiogenic factor because it promotes cell proliferation and tube formation. A recent study reported that fucoidan derived from marine plant potentiated FGF-2 induced tube formation in human endothelial cells. On the other hand, the molecular mechanisms involved in the angiogenic activity of fucoidan and FGF2 are unknown. In this study, a fucoidan treatment promoted angiogenesis induced by FGF2. The effects of fucoidan on FGF2-induced angiogenesis were confirmed by a proliferation assay using a CellTiter96 Aqueous One solution after a treatment with fucoidan and FGF2. The tube formation and wound healing assay for the angiogenic activity were also confirmed. Reverse transcription PCR showed a change in the mRNA of vascular endothelial growth factor-A (VEGF-A), intercellular adhesion molecule-1 (ICAM-1), matrix metallopeptidase9 (MMP9), and the signal transducer and activator of transcription3 (STAT3). In summary, the Fucoidan/FGF2 treatment induced an increase in cell proliferation, improved the tube formation and wound healing activity, and altered the STAT3, VEGF-A, ICAM-1, and MMP9 mRNA expression levels. Further research will be needed to provide a scientific explanation in terms of cell-signaling and confirm the present findings.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.49-55
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• 2018

Under the era of energy crisis, hydrogen energy is considered as one of the most potential alternative energies. Liquid hydrogen has much higher energy density per unit volume than gas hydrogen and is counted as the excellent energy storage method. In this study, Navier-Stokes equations based on 2-phase model were solved by using a computational fluid dynamics program and the liquefaction process of gaseous hydrogen passing through a cryogenic cooling tube was analyzed. The copper with high thermal conductivity was assumed as the material for cryogenic cooling tube. For different inlet velocities of 5 m/s, 10 m/s and 20 m/s for hydrogen gas, the distributions of fluid temperature, axial and radial velocities, and volume fractions of gas and liquid hydrogens were compared. These research results are expected to be used as basic data for the future design and fabrication of cryogenic cooling tube to transform the hydrogen gas into liquid hydrogen.

• Science of Emotion and Sensibility
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• v.18 no.4
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• pp.25-34
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• 2015

TThis study explored the requirement of fabric sensor that can measure the motion of the joint effectively by measuring and analyzing the variation in electric resistance of a sensor in accordance with bending and stretching motion of the arm by the implementation of a motion sensor utilizing conductive fabric. For this purpose, on both sides of two kinds of knitted fabric, namely 'L' fabric and 'W' fabric Single Wall Carbon Nano-Tube(SWCNT) was coated, fabric sensor was developed by finishing them in a variety of ways, and the sensor was attached to the arm band. The fabric sensor consisted of total 48 cases, namely background fabric for coating, the method of sensor attachment, the number of layer of sensors, the length of sensor, and the width of sensor. The performance of fabric motion sensors in terms of a dummy arm, that is, a Con-Trex MJ with 48 arm bands around it was evaluated. For each arm band, a total of 48, fastened around the dummy arm, it was adjusted to repeat the bending and stretching at the frequency : 0.5Hz, ROM : $20^{\circ}{\sim}120^{\circ}$, the voltage was recorded for each case after conducting three sets of repeat measurement for a total of 48 cases. As a result of the experiment, and as a consequences of the evaluation and analysis of the voltage based on the uniformity of the base line of the peak-to-peak voltage(Vp-p), the uniformity of Vp-p within the same set, and the uniformity of the Vp-p among three sets, the fabric sensors that have been configured in SWCNT coated 'L' fabric / welding / two layers / $50{\times}5mm$, $50{\times}10mm$, $100{\times}10mm$, and SWCNT coated 'W' fabric / welding / two layers / $50{\times}10mm$ exhibited the most uniform and stable signal value within 5% of the total variation rate. Through all these results of the experiment, it was confirmed that SWCNT coated fabric was suitable for a sensor that can measure the human limb operation when it was implemented as a fabric sensor in a variety of forms, and the optimal sensor types were identified.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.1
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• pp.11-21
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• 2013

The Geyoungju Ca-bentonite with dry density of 1.6 g/$cm^3$ has been considered as a standard buffer material for the disposal of high level waste in KAERI disposal system design. But it had relatively lower thermal conductivity compared with other surrounding materials, that was one of key parameters to limit the increase of the disposal density in the disposal system. In this study, various additives were selected and mixed with the Ca-bentonite in different mixing methods in order to increase the thermal conductivity from 0.8 W/mK to 1.0 W/mK. As an additive, CNT (Cabon Nano Tube), graphite, alumina, CuO, and $Fe_2O_3$ were selected, which are chemically stable and have good thermal conductivity. As mixing methods, dry hand-mixer mixing, wet milling and dry ball mill mixing were applied for the mixing. Above all, the ball mill mixing was proved to be most effective since the produced mixture was most homogeneous and showed higher increase in the thermal conductivity. From this study, it was confirmed that the thermal conductivity for the Geyoungju Ca-bentonite could be improved by adding small amount of highly thermal conductive material to 1.0 W/mk. In conclusion, it was believed that the experimental results will be valuable in the disposal system design if the additive effects on the swelling and permeability on the compact bentonite are also approved in further studies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2904-2912
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• 2011

Water qualities in the decentralized water treatment plants do not frequently satisfy the water standard limit, in particular, fluoride and nitrate are notorious for the poor removal. In this study, an electro-adsorption equipped with carbon nonotube (CNT) electrodes were carried out to effectively remove the nitrate and fluoride in the decentralized water treatment plants. Two types of CNT electrodes, coating and sintering electrodes were applied. Coating electrodes were made based on different kinds of binder and sintering electrodes were made based on different sintering temperature. Removal of fluoride and nitrate when the coated electrodes with organic binder were used for electro-adsorption were 46 and 99.9% respectively, which were better performances than the coated electrodes with inorganic binder were used. On the other hand, removal of fluoride and nitrate when the electrodes sintered at higher temperature ($1,000^{\circ}C$) were 77 and 87% respectively, which were better performances than the electrodes sintered at lower temperature ($850^{\circ}C$). As a consequences, the electro-adsorption equipped with a CNT electrodes could be an potential alternative process for the removal of fluoride and nitrate in a decentralized water treatment plants if proper current density and contact time were applied.