• Applied Chemistry for Engineering
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• v.29 no.2
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• pp.155-161
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• 2018

For the efficient recovering of collapsed sloped soil, using a soil binder that can support the soil strongly and help the growth of plants is very important. The soil binder should also have functions of recovering the soil ecologically as well as be environmental friendly materials. In this research, optimum values of the water content and permeability and direct shear strength were searched by adding the water absorbent and coagulant into the soil binder. The polyacrylamide (PAM) with various anionic strength, super absorbent polymer (SAP) and cellulose ether (CE) were used as a soil binder, water absorbent and coagulant, respectively. Effects of the soil binder on the characteristics of soil were observed by changing the mixing ratio of PAM, SAP and CE. Experimental results showed that the soil binder increased the direct shear strength tens of times and the water content around two times, whereas decreased the water permeability. Also, the addition of CE to increase the coagulation of SAP increased more of the direct shear strength and water content.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.12
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• pp.5059-5062
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• 2015

Background: ALL is an irredeemable disease due to the resistance to treatment. There are several influences which are involved in such resistance to chemotherapy, including oxidative stress as a result of the generation of reactive oxygen species (ROS) and presence of hypodiploid cells. Cluster of differentiation 26 (CD26), also known as dipeptidyl peptidase-4, is a 110 kDa, multifunctional, membrane-bound glycoprotein. Aim and objectives: The aim of this study was to evaluate the clinical significance of serum CD26 in patients with acute lymphoblastic leukaemia patients in the post remission induction phase, as well as the relationship between CD26 activity and the oxidative stress status. Materials and Methods: CD26, total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI), in addition to activity of related enzymes myeloperoxidase, glutathione-s-transferase and xanthine oxidase, were analysed in sixty children with acute lymphoblastic leukaemia in the post remission induction phase. Results: The study showed significant elevation in CD26, TOS and OSI levels in patients with acute lymphoblastic leukaemia in the post remission induction phase in comparison to healthy control samples. In contrast, myeloperoxidase, glutathione-s-transferase and xanthine oxidase activities were decreased significantly. A significant correlation between CD26 concentration and some oxidative stress parameters was evident in ALL patients. Conclusions: Serum levels of CD26 appear to be useful as a new biomarker of oxidative stress in children with acute lymphoblastic leukaemia in the post remission induction phase, and levels of antioxidants must be regularly estimated during the treatment of children with ALL.

• Composites Research
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• v.28 no.5
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• pp.285-290
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• 2015

Multiscale multiphysics in structural batteries make mechanical property testing difficult. In this research, the effect of electrolyte-coating on the mechanical performance of carbon fabric was studied using a suitable mechanical test method for structural batteries. For this experiment, two types of specimens were determined their dimension according to ASTM. One type of specimen was smaller than the standard dimension. The specimens were coated by spreading the electrolyte material on carbon fabric, hardened using epoxy, and tested for tensile properties using universal testing machine. As a result, it was found that the mechanical properties of carbon fabric were not influenced by electrolyte coating. In addition, the small-scale specimen used in this experiment was determined to be sufficiently reliable.

• Composites Research
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• v.29 no.3
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• pp.98-103
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• 2016

This paper deals with the fabrication and verification of the microwave absorbing structure using semiconductive fiber reinforced composite. Two kinds of fiber were used to fabricate composites. Electromagnetic properties of the composites were measured by freespace measurement system over X-band. Two single slab absorbers and a double slab absorber were designed by thickness optimization method. Single slab absorbers did not show good microwave absorption performance because the permittivity is away from non-reflection curve. Double slab absorber complemented the limitations on single slab absorber and it showed good microwave absorption performance. Double slab absorber showed -43.9 dB loss near 10 GHz.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.1
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• pp.63-71
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• 2020

Recently, to improve convenience, flexible electronics are quickly being developed for a number of application areas. Flexible electronic devices comprise characters such as being bendable, stretchable, foldable, and wearable. Effectively manufacturing flexible electronic devices requires high efficiency, low costs, and simple processes for manufacturing technology. Through this study, we enabled the rapid production of multifunctional flexible bending sensors using a simple, low-cost Fused Deposition Modeling (FDM) 3D printer. Furthermore, we demonstrated the possibility of the rapid production of a range of functional flexible bending sensors using a simple, low-cost FDM 3D printer. Accurate and reproducible functional materials made by FDM 3D printers are an effective tool for the fabrication of flexible sensor electronic devices. The 3D-printed flexible bending sensor consisted of polyurethane and a conductive filament. Two patterns of electrodes (straight and Hilbert curve) for the 3D printing flexible sensor were fabricated and analyzed for the characteristics of bending displacement. The experimental results showed that the straight curve electrode sensor sensing ability was superior to the Hilbert curve electrode sensor, and the electrical conductivity of the Hilbert curve electrode sensor is better than the straight curve electrode sensor. The results of this study will be very useful for the fabrication of various 3D-printed flexible sensor devices with multiple degrees of freedom that are not limited by size and shape.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.491-491
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• 2011

Transparent and flexible electronic devices that are light-weight, unbreakable, low power consumption, optically transparent, and mechanical flexible possibly have great potential in new applications of digital gadgets. Potential applications include transparent displays, heads-up display, sensor, and artificial skin. Recent reports on transparent and flexible field-effect transistors (tf-FETs) have focused on improving mechanical properties, optical transmittance, and performances. Most of tf-FET devices were fabricated with transparent oxide semiconductors which mechanical flexibility is limited. And, there have been no reports of transparent and flexible all-organic tf-FETs fabricated with organic semiconductor channel, gate dielectric, gate electrode, source/drain electrode, and encapsulation for sensor applications. We present the first demonstration of transparent, flexible all-organic sensor based on multifunctional organic FETs with organic semiconductor channel, gate dielectric, and electrodes having a capability of sensing infrared (IR) radiation and mechanical strain. The key component of our device design is to integrate the poly(vinylidene fluoride-triflouroethylene) (P(VDF-TrFE) co-polymer directly into transparent and flexible OFETs as a multi-functional dielectric layer, which has both piezoelectric and pyroelectric properties. The P(VDF-TrFE) co-polumer gate dielectric has a high sensitivity to the wavelength regime over 800 nm. In particular, wavelength variations of P(VDF-TrFE) molecules coincide with wavelength range of IR radiation from human body (7000 nm ~14000 nm) so that the devices are highly sensitive with IR radiation of human body. Devices were examined by measuring IR light response at different powers. After that, we continued to measure IR response under various bending radius. AC (alternating current) gate biasing method was used to separate the response of direct pyroelectric gate dielectric and other electrical parameters such as mobility, capacitance, and contact resistance. Experiment results demonstrate that the tf-OTFT with high sensitivity to IR radiation can be applied for IR sensors.

• Journal of Microbiology and Biotechnology
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• v.26 no.6
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• pp.999-1010
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• 2016

Ganoderma lucidum BCCM 31549 has a long established role for its therapeutic activities. In this context, much interest has focused on the possible functions of the (1,3)-β-D-glucan (G) produced by these cultures in a stirred-tank bioreactor and extracted from their underutilized mycelium. In the existing study, we report on the systematic production of G, and its sulfated derivative (GS). The aim of this study was to investigate G and its GS from G. lucidum in terms of their antibacterial properties and cytotoxicity spectrum against human prostate cells (PN2TA) and human caucasian histiocytic lymphoma cells (U937). ¹H NMR for both G and GS compounds showed β-glycosidic linkages and structural similarities when compared with two standards (laminarin and fucoidan). The existence of characteristic absorptions at 1,170 and 867 cm^-1 in the FTIR (Fourier Transform Infrared Spectroscopy) for GS demonstrated the successful sulfation of G. Only GS exhibited antimicrobial activity against a varied range of test bacteria of relevance to foodstuffs and human health. Moreover, both G and GS did not show any cytotoxic effects on PN2TA cells, thus helping demonstrate the safety of these polymers. Moreover, GS showed 40% antiproliferation against cancerous U937 cells at the low concentration (60 μg/ ml) applied in this study compared with G (10%). Together, this demonstrates that sulfation clearly improved the solubility and therapeutic activities of G. The water-soluble GS demonstrates the potential multifunctional effects of these materials in foodstuffs.

• Corrosion Science and Technology
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• v.18 no.5
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• pp.212-219
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• 2019

This paper reviews recent approaches to develop composite polymer-containing coatings by plasma electrolytic oxidation (PEO) using various low-molecular fractions of superdispersed polytetrafluoroethylene (SPTFE). The features of the unique approaches to form the composite polymer-containing coating on the surface of MA8 magnesium alloy were summarized. Improvement in the corrosion and tribological behavior of the polymer-containing coating can be attributed to the morphology and insulating properties of the surface layers and solid lubrication effect of the SPTFE particles. Such multifunctional coatings have high corrosion resistance ($R_p=3.0{\times}10^7{\Omega}cm^2$) and low friction coefficient (0.13) under dry wear conditions. The effect of dispersity and ${\xi}$-potential of the nanoscale materials ($ZrO_2$ and $SiO_2$) used as electrolyte components for the plasma electrolytic oxidation on the composition and properties of the coatings was investigated. Improvement in the protective properties of the coatings with the incorporated nanoparticles was explained by the greater thickness of the protective layer, relatively low porosity, and the presence of narrow non-through pores. The impedance modulus measured at low frequency for the zirconia-containing layer (${\mid}Z{\mid}_{f=0.01Hz}=1.8{\times}10^6{\Omega}{\cdot}cm^2$) was more than one order of magnitude higher than that of the PEO-coating formed in the nanoparticles-free electrolyte (${\mid}Z{\mid}_{f=0.01Hz}=5.4{\times}10^4{\Omega}{\cdot}cm^2$).

• Applied Chemistry for Engineering
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• v.30 no.2
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• pp.167-177
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• 2019

The jadeite powder has a disadvantage affecting the stability of the formulation due to the agglomeration of the powder when applied to cosmetic formulations. To overcome this problem, a new composite powder was prepared by modifying the surface of jadeite powder and applied to foundation pact and sun stick. In this study, a triethoxycaprylylsilane among various surface modifiers was selected as an optimum component, and applied to each formulation by making the jadeite powder composite. As a result, the foundation pact maintained the clarity of the product color, and the sun stick gave about 30% higher UV blocking effect in the UVB area compared with that of the blank. In the user sensory evaluation, the formulation containing the jadeite powder composite showed a high score for the overall indicator. The stability evaluation of the formulation was also confirmed that it was stable against discoloration, detachment and hardness. In conclusion, the jadeite powder composite is stable as an inorganic pigment which is applicable to cosmetics as a multifunctional material while maintaining the color clarity of the product and acting as a booster for sunscreen agents.

• Composites Research
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• v.37 no.3
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• pp.155-161
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• 2024

Boron nitride nanotubes and carbon nanotubes are the most representative one-dimensional nanostructures, and have received great attention as reinforcement for multifunctional composites for their excellent physical properties. The two nanotubes have similar excellent mechanical stiffness, strength, and heat conduction properties. Therefore, the reinforcing effect of these two nanotubes is greatly influenced by the properties of their interface with the polymer matrix. In this paper, recent comparative studies on the reinforcing effect of boron nitride nanotubes and carbon nanotubes through experimental pull-out test and in-silico simulation are summarized. In addition, the conflicting aspect of the two different nanotubes with structural defects in their side wall is discussed on the viscoelastic damping performance of nanocomposites.