• Membrane Journal
• /
• v.27 no.1
• /
• pp.53-59
• /
• 2017

In this study, the composite membranes prepared by sulfonated graphene oxide (sGO) and Nafion were developed as proton exchange membranes (PEMs) for polymer electrolyte membrane fuel cells (PEMFCs). The sGO/Nafion composite membranes were prepared by mixing Nafion solution with the sGO dispersed in a binary solvent system to improve dispersity of sGO. The composite membranes were investigated in terms of ionic conductivity, ion exchange capacity (IEC), FT-IR, TGA and SEM, etc. As a result, the binary solvent system, i.e., ortho-dichlorobenzene (ODB) and N,N-dimethylacetamide (DMAc), were used to obtain high dispersion of sGO particles in Nafion solution, and the ionic conductivity of the sGO/Nafion composite membrane showed $0.06Scm^{-1}$ similar to other research results at lower water uptake, 11 wt%.

• The Journal of Korean Association of Computer Education
• /
• v.18 no.2
• /
• pp.21-33
• /
• 2015

This paper aims at developing IT convergence robot education contents using open hardware-based GoGo Board and presenting three cases that were applied into educational settings with elementary and middle school students. Several types of data for their activities were collected: photos, work output, survey data, video data and interview with robot teacher and students. Each student experienced building up a GoGo Bumper Car with touch sensors attached at front and back sides and figuring out the principle of digital board control and operating of electronic devices by sensing. The participants, in the following phases, conducted domino chain-reaction with GoGo Bumper Cars and acquiring GoGo Driving Licence by driving test on three different road maps. Students in a gifted education program creatively implemented their own ideas as part of robotic art. The result of case analysis showed that the proposed project provides students not only intimacy for technology, fun, concentration but her own empowerment for developing ideas and creative implementation.

• Journal of Oral Medicine and Pain
• /
• v.31 no.2
• /
• pp.167-176
• /
• 2006

Recent studies have shown that there are significant increasing facial asymmetry using 3-dimensional imaging. This study use panorama view and PA cephalograph that were low in price and make good use in dentistry. For this study, 35 persons without remarkable malocclusion were selected, they had panorama view and PA cephalograph, make written questionnaire about facial asymmetry cognition and masticatory pattern. Data obtained were statistically processed by the SPSS Windows program and the results of this study were as follows: 1. There were significant difference between Rt and Lt. on Co-Go, Co-Ag, Co-Go-Ag, Go-Me- Ag. 2. In panorama view, There were significant difference between Rt. and Lt Co-Ag that chewing right side, Rt. and Lt. Co-Go that chewing left side, 3. In PA cephalograph view, There were significant difference in Rt. and Lt. Cg-Go, Rt. and Lt. Co-Ag that chewing right side, Rt. and Lt. Cg-Go that chewing left side 4. There were significant difference in Rt. and Lt. Co-Go, CO-si-CR, go-ME-Ag that cogniting facial asymmetry.

• Journal of the Microelectronics and Packaging Society
• /
• v.26 no.3
• /
• pp.43-49
• /
• 2019

In this study, a new approach using graphene oxide (GO) powder-composited Sn-3.0Ag-0.5Cu(in wt.%) solder paste for improving the bending reliability of solder joints between a flexible substrate and small outline package (SOP) was suggested. The GO addition slightly affected the melting temperature, however, the change in the melting temperature was not significant. Meanwhile, we observed the addition of GO could suppress IMC growth and IMC thickness of solder joint during the reflow process. Moreover, the cyclic bending test was also performed for evaluation of reliability in solder joint and we could improve the cyclic bending reliability of solder joint by adding GO powders. For 0.2 wt.% of GO added to the solder joint, the bending lifetime was increased to 20% greater than that without GO. Pull strength and ductility of the solder joint with GO were also higher than those of the joint without GO and it was assumed that this effect by adding GO could contribute to improve cyclic bending reliability of solder joint.

• The Journal of Internal Korean Medicine
• /
• v.21 no.4
• /
• pp.555-563
• /
• 2000

Objective : In order to know the antibacterial effects of Kyungok-go against Mycobacteria tuberculosis, Methods : In this study, I inverstigated these effects in terms of combination of other antibiotics with and without Kyungok-go on several different media conditions. Results: On Ogawa medium, Kyungok-go of the $10{\mu}/ml$ concentration showed the anti-Mycobacteria tuberculosis activity against antibiotic drug-sensitive strain. On Middle-blue medium, Kyungok-go of the $10{\mu}/ml$ concentration showed the anti-Mycobacteria tuberculosis activity against antibiotic drug-sensitive strain. Kyungok-go showed the anti mycobacteria tuberculosis activity with the meaningful result above a certain concentration. The resistance against M, tuberculosis as the concentration of Kyungok-go was decreased significantlly on the high concentration($500{\mu}/ml$) When rifampicin and Kyungok-go were used together, the resistance was decreased with the statistical significance as to the persistant antibacterial effect against M. tuberculosis, When ciprofloxacin and Kyungok-go were used together, the resistance was decreased with the statistical significance as to the persistant antibacterial effect against M. tuberculosis, The combination of treatment, Kyungok-go with both rifampicin and ciprofloxacin, showed much better antibacterial effect against M, tuberculosis than antibiotics alone. Conclusions : This study shows that Kyungok-go has antibacterial effect against M. tuberculosis and in the combination of treatment, Kyungok-go with antibiotics, showed much better antibacterial effect against M. tuberculosis than antibiotics alone,.

• Polymer(Korea)
• /
• v.35 no.6
• /
• pp.565-573
• /
• 2011

The nanocomposites containing graphene oxide (GO) were prepared in order to improve the mechanical properties of poly(methyl methacrylate)/aluminum hydroxide (PMMA/AH) composites. GO was prepared from graphite by oxidation of Hummers method followed by exfoliation with thermal treatment. The surface of GO was modified by oxygen plasma in various exposure times from 0 to 70 min to improve interfacial compatibility. Compared with PMMA/AH composites, the nanocomposites containing GO modified with oxygen plasma for the exposure time up to 50 min showed significant increases in flexural strength, flexural modulus, Rockwell hardness, Barcol hardness, and Izod impact strength. The morphology of fracture surface showed an improved interfacial adhesion between PMMA/AH composites and GO, which was properly treated with oxygen plasma. The mechanical properties of nanocomposites were deteriorated by increasing the content of GO above 0.07 phr due to the nonuniform dispersion of GO.

• The Korea Journal of Herbology
• /
• v.32 no.3
• /
• pp.9-17
• /
• 2017

Objectives : Kyeongok-go has the effect of antioxidant, anti-cancer, improving fatigue, and hyperlipidemia, but it is not easy to use in clinical practice becausee of the complicated manufacturing process of heat control and moisture control. The aim of this study was to explore the lipid improvement effect of new manufacturing methods prodeced Kyeongok-go in hyperlipidemia rats. Methods : The SD rats were divided randomly into 8 groups of six animals each : Normal rats (Nor), hyperlipidemia rats (Con), hyperlipidemia rats treated with Spirulina 60 mg/kg(SP60), hyperlipidemia rats treated with Commercial Kyeongok-go 1 g/kg (K0), hyperlipidemia rats treated with Kyeongok-go manufactured by heating mantle 1 g/kg (K1), hyperlipidemia rats treated with ginseng fermentation Kyeongok-go 1 g/kg (KF), hyperlipidemia rats treated with Kyeongok-go with black ginseng 1 g/kg (BK), hyperlipidemia rats treated with black ginseng fermentation Kyeongok-go 1 g/kg (BKF). The experimental group induced hyperlipidemia by eating high cholesterol diet for 8 weeks. Also, we compared Kyeongok-go manufacturing method using the new method compared with traditional method. Results : As a result, the improvement effect of hyperlipemia using the new method showed the similar or better improvement effect compared with the conventional method, and it is considered that the Kyeongok-go manufacturing method using the new method can be substituted for the traditional Kyeongok-go manufacturing method. Conclusion : In conclusion, these results suggest that new manufacturing methods prodeced Kyeongok-go has the potential as a anti-hyperlipidemia material which possess lipid improvement activities.

• Membrane Journal
• /
• v.33 no.6
• /
• pp.416-426
• /
• 2023

In this study, hindered amine-grafted graphene oxide (HA-GO) with antioxidant properties was prepared and incorporated into Nafion-based composite membranes as an effective filler material for polymer electrolyte membrane fuel cell applications. HA-GO was synthesized via a ring-opening reaction between amine groups in 4-amino-2, 2, 6, 6-tetramethyl piperidine and epoxy groups on the surface of GO. Nafion-based composite membranes containing different weight contents of HA-GO were fabricated to compare the polymer electrolyte membrane properties with those of the pure Nafion membrane. The composite membranes with HA-GO were found to have better mechanical properties, chemical stability, and proton conductivity than the pure Nafion membrane. In particular, the conductivity retention behavior confirmed by the decrease in proton conductivity after Fenton's test of the composite membranes was better than that of the pure Nafion membrane due to the incorporation of HA-GO with effective antioxidant properties.

• Carbon letters
• /
• v.12 no.3
• /
• pp.138-142
• /
• 2011

Poly(vinyl alcohol) (PVA) composites with various graphite oxide (GO) contents (0 to 10 wt%) were prepared by sonicating the mixture of PVA and GO, followed by crosslinking with glutaraldehyde. GO was pre-treated with oxyfluorination ($O_2:F_2$ = 8:2) in order to modify the surface of GO to allow it to carry hydrophilic functional groups. PVA/GO composite hydrogels were characterized by scanning electron microscopy and Fourier-transform infrared spectrometer (FT-IR). The morphology of the PVA/GO composite hydrogels and the variations in soluble gel portion were investigated under various GO contents and UV irradiation doses. The variation in the chemical structure of photo degraded PVA/GO composite hydrogels was studied by FT-IR. The photochemical stability of PVA/GO composite hydrogels under UV irradiation was found to improve noticeably with increasing content of uniformly dispersed GO.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.39 no.1
• /
• pp.16-24
• /
• 2011

In this paper, we propose a new guidance law for target observability enhancement, which can control both terminal impact angle and acceleration. The proposed guidance law is simple form, combined conventional time-to-go polynomial guidance and a additional bias term which consists of relative position and proportional gain. The guidance law provides oscillatory flight trajectory and it maintains the conventional time-to-go polynomial guidance performance. To investigate the characteristics of the guidance law, we derive the closed-form solution, and various simulations are performed for proving the validity of the proposed guidance.