• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.258-264
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• 2018

In this study, the improved performance of sprayed green soil was evaluated by incorporating functional additives. The optimal mixing ratio of the thickener and super-absorbent polymer, as an additive for moisture supply to the growth of plants within the range of mixing ratios that gives sufficient strength of green soil, was 5% and 1%, respectively. Using Portland cement as a main binder, the pH of the green soil was 9.1. To solve this alkali problem, the mixing proportion was improved so that the pH of the green soil was approximately 7.2 by mixing more than 10% of the chelate resin. The soil conductivity was measured to be 280 ~ 350mS/m under all the mixing conditions. This satisfied the criterion of less than 1000mS/m on the slope surface. As a result of measuring the soil hardness of the green soil prepared under the optimal mixing conditions of functional additives, it satisfied the criteria of 18 ~ 23mm when sprayed under a 1 bar pressure. The rebound rate was less than 15% when spraying green soil on a 75 % slope, and the hardness of the sprayed green soil was more than 18 mm.

• Resources Recycling
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• v.29 no.6
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• pp.15-26
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• 2020

In recent years, there is an increasing interest in environmental friendly treatment of waste-plastics in terms of the generation of microplastics. Accordingly, the recycling of waste-plastics is very important because it provides advantages of volume reduction, mitigation of carbon dioxide emission, and reproduction of value-added products. In particular, in order to recycle the eco-friendly waste-plastics, it is necessary to use a physical separation methods, and among them, flotation separation, which can separate material (i.e., polymer component) in waste-plastics is well known as a very effective separation method in terms of material recycle. Therefore, in this review, the research trend of flotation separation for effective separation of mixture waste-plastics was investigated. In addition, through the reported research results, approaches to use as new functional materials from polymers, which are raw materials for waste-plastics, are summarized.

• Progress in Superconductivity and Cryogenics
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• v.19 no.1
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• pp.47-50
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• 2017

Carbon is proven to be very effective in pinning the magnetic vortices and improving the superconducting performance of $MgB_2$ at high fields. In this work, we have used polymethyl methacrylate (PMMA) polymer as a safe and cost effective carbon source. The effects of molecular weight of PMMA on crystal structure, microstructure as well as on superconducting properties of $MgB_2$ were studied. X-ray diffraction analysis revealed that there is a noticeable shift in (100) and (110) Bragg reflections towards higher angles, while no shift was observed in (002) reflections for $MgB_2$ doped with different molecular weights of PMMA. This indicates that carbon could be substituted in the boron honeycomb layers without affecting the interlayer interactions. As compared to undoped $MgB_2$, substantial enhancement in $J_c(H)$ properties was obtained for PMMA-doped $MgB_2$ samples both at 5 K and 20 K. The enhancement could be attributed to the effective carbon substitution for boron and the refinement of crystallite size by PMMA doping.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.1.1-1.1
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• 2011

Printed electronics based on the direct writing of solution processable functional materials have been of paramount interest and importance. In this talk, the synthesis of printable inorganic functional materials (conductors and semiconductors) for thin-film transistors (TFTs) and photovoltaic devices, device fabrication based on a printing technique, and specific characteristics of devices are presented. For printable conductor materials, Ag ink is designed to achieve the long-term dispersion stability and good adhesion property on a glass substrate, and Cu ink is sophisticatedly formulated to endow the oxidation stability in air and even aqueous solvent system. The both inks were successfully printed onto either polymer or glass substrate, exhibiting the superior conductivity comparable to that of bulk one. In addition, the organic thin-film transistor based on the printed metal source/drain electrode exhibits the electrical performance comparable to that of a transistor based on a vacuum deposited Au electrode. For printable amorphous oxide semiconductors (AOSs), I introduce the noble ways to resolve the critical problems, a high processing temperature above $400^{\circ}C$ and low mobility of AOSs annealed at a low temperature below $400^{\circ}C$. The dependency of TFT performances on the chemical structure of AOSs is compared and contrasted to clarify which factor should be considered to realize the low temperature annealed, high performance AOSs. For photovoltaic application, CI(G)S nanoparticle ink for solution processable high performance solar cells is presented. By overcoming the critical drawbacks of conventional solution processed CI(G)S absorber layers, the device quality dense CI(G)S layer is obtained, affording 7.3% efficiency CI(G)S photovoltaic device.

• Korean Journal of Optics and Photonics
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• v.15 no.2
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• pp.109-113
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• 2004

We have manufactured and characterized the fiber-to-Planar Waveguide Coupler for analysis of the photo-induced refractive index change of DM-BTE .(l,2-bis[2,5-dimethylthio-phen-3-yl]-hexafluorocyclopentene) When irradiated with ultraviolet light, the colorless diarylethene(DM-BTE)-crystal turned red while keeping the crystal shape. The red color was bleached by irradiation with visible light(λ＞450 nm). The resonant wavelength was shifted and recovered owing to the refractive index variation of the planar waveguide because of its photo-functional properties on exposure to UV and visible light. The wavelength responses of this switch by UV exposure were measured as 0.057 nm/sec with saturation time of 60 seconds. and when illuminated by visible light, resonance wavelength variations were measured as 0.028 nm/sec, with recovery time of 140 seconds.

• Journal of Environmental Science International
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• v.22 no.3
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• pp.341-346
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• 2013

The purpose of this study was to assess the effects of Cordyceps militaris extract supplementation on the improvement of blood glucose, lipid compositions and hepatic functional enzyme activities in the serum of streptozotocin(STZ, 50 mg/kg BW, IP injection)-induced diabetic rats fed the experimental diets for 5 weeks. The concentrations of blood glucose and lipid compositions(total cholesterol, ${\beta}$-lipoprotein, free cholesterol, cholesteryl ester, triglyceride and phospholipid) and atherosclerotic index in serum were significantly lower in the DM+CM group than in the DM group, whereas the ratio of HDL-cholesterol concentration to total cholesterol in the DM+CM group were higher than in the DM group. The activities of hepatic functional enzymes(aminotransferase, LDH and ALP) in serum were lower in the Cordyceps militaris extract administration group(group DM+CM) than in the hyperglycemic DM group. The results shown above suggested that Cordyceps militaris extract supplementation effectively improves blood glucose and atherosclerosis in the serum of diabetic rats.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2245-2250
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• 2014

A new accepter unit, 6,7-difluoro-2,3-dihexylquinoxaline, was prepared and utilized for the synthesis of the conjugated polymers containing electron donor-acceptor pair for OPVs. New series of copolymers with dioctyloxybenzodithiophene as the electron rich unit and 6,7-difluoro-2,3-dihexylquinoxaline as the electron deficient unit are synthesized. The solid films of poly[2,6-(4,8-bis(2-ethylhexyloxy)benzo[1,2-b:4,5-b']dithiophene)-alt-5,8-(6,7-difluoro-2,3-dihexylquinoxaline)] (PBQxF) and poly[2,6-(4,8-bis(2-ethylhexyloxy) benzo[1,2-b:4,5-b']dithiophene)-alt-5,8-(6,7-difluoro-2,3-dihexyl-5,8-di(thiophen-2-yl) quinoxaline)] (PBDTQxF) show absorption bands with maximum peaks at about 599 and 551 nm and the absorption onsets at 692 and 713 nm, corresponding to band gaps of 1.79 and 1.74 eV, respectively. The devices comprising PBQxF with $PC_{71}BM$ (1:2) showed open-circuit voltage ($V_{OC}$) of 0.64 V, short-circuit current density ($J_{SC}$) of $1.58mA/cm^2$, and fill factor (FF) of 0.39, giving power conversion efficiency (PCE) of 0.39%. To obtain absorption in the longer wavelength region, thiophene units without any alkyl group are incorporated as one of the monomers in PBDTQxF, which may result in low solubility of the polymers to lead lower efficiency.

• 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.

• KSBB Journal
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• v.28 no.2
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• pp.115-122
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• 2013

Volatile flavor compounds of Chamaecyparis obtuse essential oil were extracted by simultaneous steam distillation extraction (SDE) and supercritical fluid extraction (SFE) and analyzed by GC-MS. A total of 48 and 50 components were identified in essential oil by SDE and SFE, respectively. Monoterpenes, oxygenated monoterpenes, sesquiterpenes, oxygenated sesquiterpenes, and diterpenes in essential oil by SDE were 37.24, 10.9, 9.61, 0.22, and 0.22%, respectively. In the case of SFE, they were 19.1, 23.3, 22.66, 1.31, and 10.57%, respectively. Antioxidant activities were increased with the increase of essential oil up to $80{\mu}L/mL$, irrespective of extraction method. Especially, when the essential oil concentration extracted by SDE was increased from 20 to $80{\mu}L/mL$, the antioxidant activity was increased from 10.5 to 55.1%. However, over $80{\mu}L/mL$ of essential oil, an equilibrium state was maintained. In the case of essential oil extracted by SFE, it was decreased compared to that of SDE. For the improvement of atopic dermatitis, various cosmetics such as an ato-cide soap, ato-cide spray, and ato-cide lotion containing essential oil extracted by SFE were tested. About over 90% was useful for the improvement of atopic dermatitis after 4 weeks of clinical trial targeting 40 female adults. These results demonstrate that ato-cide soap, ato-cide spray, and ato-cide lotion containing essential oil extracted by SFE could be used in functional cosmetics.

• Journal of Microbiology and Biotechnology
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• v.29 no.3
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• pp.500-505
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• 2019

Staphylococcus aureus is a round-shaped, gram-positive bacterium that can cause numerous infectious diseases ranging from mild infections such as skin infections and food poisoning to life-threatening infections such as sepsis, endocarditis and toxic shock syndrome. Various antibiotic-resistant strains of S. aureus have frequently emerged, threatening human lives significantly. Despite much research on the genetics of S. aureus, many of its genes remain unknown functionally and structurally. To counteract its toxins and to prevent the antibiotic resistance of S. aureus, our understanding of S. aureus should be increased at the proteomic scale. SAV0927 was first sequenced in an antibiotic resistant S. aureus strain. The gene is a conserved hypothetical protein, and its homologues appear to be restricted to Firmicutes. In this study, we determined the crystal structure of SAV0927 at $2.5{\AA}$ resolution. The protein was primarily dimeric both in solution and in the crystals. The asymmetric unit contained five dimers that are stacked linearly with ${\sim}80^{\circ}$ rotation by each dimer, and these interactions further continued in the crystal packing, resulting in a long linear polymer. The crystal structures, together with the network analysis, provide functional implications for the SAV0927-mediated protein network.