• Journal of the Korean Electrochemical Society
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• v.27 no.2
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• pp.73-79
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• 2024

As the use of fossil fuels has gradually increased, so has the emission of greenhouse gases such as carbon dioxide, leading to environmental problems. As a result, lithium-ion batteries (LiB) have emerged as the solution to this issue. To manufacture medium to large-sized lithium-ion batteries (LiB), it requires electrodes with high capacity and fast charging capabilities. Silicon (Si) is considered a next-generation anode with high-capacity properties, so, reduced graphene oxide (rGO) was compounded with Si@resorcinol-formaldehyde resin (RF) composite to prevent the volume expansion of Si. It was confirmed that the composite anode prepared exhibited improved capacity and enhanced stability.

• Journal of Surface Science and Engineering
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• v.57 no.4
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• pp.265-273
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• 2024

An amperometric sensor for measuring indole-3-acetic acid (IAA) was studied based on a screen-printed carbon electrode (SPCE) coated with a reduced graphene oxide composite electrocatalyst. The PEI-GO dispersion is uniformly formed through a nucleophilic substitution reaction between the active amine group of Polyethyleneimine (PEI) and the epoxide group exposed on the surface of graphene oxide. And The 3-dimensional PEI-rGO AG (Polyethyleneimine-reduced graphene oxide aerogel) complex was easily prepared through simple heat treatment of the combined PEI-GO dispersion. The proposed composite catalyst electrode, PEI-rGO AG/SPCE, showed a two linear relationship in the low and high concentrations in IAA detection, and the linear equation was I_pa = 0.2883C + 0.0883 (R²=0.9230) at low concentration and Ipa = 0.00464C + 0.6623 (R²=0.9894) at high concentration was proposed, and the detection limit was calculated to be 203.5nM±33.2nM. These results showed the applicability of the PEI-rGO AG composite catalyst as an electrode material for electrocatalysts for the detection of IAA.

• Proceedings of the Korea Contents Association Conference
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• 2011.05a
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• pp.361-362
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• 2011

본 연구는 사건관련전위를 이용하여 정신병질자들이 정서인식에 따른 반응억제의 어려움이 있는지를 알아보기 위해 수행되었다. 교도소에 수용 중인 수형자들을 대상으로 PCL-R(Psychopathy Checklist-Revised)의 점수에 따라 6명의 정신병질 수형자집단과 4명의 정상 수형자집단을 선별하고, 얼굴자극을 이용한 시각 Go/NoGo 과제를 실시하였다. 모든 피험자들은 Go 자극에 버튼을 누르고 NoGo 자극에 버튼을 누르지 않도록 지시를 받았으며, 과제를 실시하는 동안 사건관련전위를 측정하였다. 과제 1에서는 공포표정을 NoGo자극으로 사용하고 중성표정을 Go자극으로 사용하였으며, 과제 2에서는 슬픈 표정을 NoGo자극으로 사용하고 중성표정을 Go자극으로 사용하였다. 정신병질 수형자집단은 공포표정의 NoGo P3 진폭이 중성표정의 Go P3 진폭보다 크게 나타난 반면에 정상 수형자집단은 공포표정과 중성표정 간의 P3 요인의 진폭이 유사하거나 공포표정의 NoGo P3 진폭보다 중성표정의 Go P3 진폭이 더 크게 나타났다. P3 잠재기를 분석한 결과, 정신병질 수형자집단은 슬픔 표정자극의 NoGo조건에서 중성표정자극의 Go조건보다 느린 P3 잠재기를 나타낸 반면, 정상 수형자집단은 NoGo조건에서 Go조건보다 빠른 P3 잠재기를 나타냈다. 정서인식검사결과, 정신병질 수형자집단은 정상 수형자 집단보다 유의미하게 낮은 정확도를 나타냈다. 이러한 결과는 정신병질자들이 공포, 슬픔과 같은 부정적인 정서를 인식한 후에 반응을 억제하는데 인지적인 어려움을 겪는다는 것을 보여준다.

• Laser Solutions
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• v.15 no.4
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• pp.1-5
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• 2012

We demonstrate that reduced graphene oxide (rGO) coated thin aluminum film is an effective optoacoustic transmitter for generating high pressure and high frequency ultrasound previously unattainable by other techniques. The rGO layer of different thickness is deposited between a 100 nm-thick aluminum film and a glass substrate. Under a pulsed laser excitation, the transmitter generates enhanced optoacoustic pressure of 64 times the aluminum-alone transmitter. A promising optoacoustic wave generation is possible by optimizing thermoelasticity of metal film and thermal conductivity of rGO in the proposed transmitter for laser-induced ultrasound (LIUS) applications.

• ETRI Journal
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• v.32 no.5
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• pp.827-830
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• 2010

For an adaptive cruise control (ACC) stop-and-go system in automotive applications, three radar sensors are needed because two 24 GHz short range radars are used for object detection in an adjacent lane, and one 77 GHz long-range radar is used for object detection in the center lane. In this letter, we propose a single sensor-based 24 GHz radar with a detection capability of up to 150 m and ${\pm}30^{\circ}$ for an ACC stop-and-go system. The developed radar is highly integrated with a high gain patch antenna, four channel receivers with GaAs RF ICs, and back-end processing board with subspace based digital beam forming algorithm.

• Applied Chemistry for Engineering
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• v.33 no.6
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• pp.600-605
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• 2022

In this study, nitrogen oxide (NO_x) removal experiments were performed using a graphene based ceramic filter coated with a V₂O₅-WO₃-TiO₂ catalyst. Graphene oxide (GO) was prepared by Hummer's method using graphite, and the reduced graphene oxide was produced by reducing with hydrazine (N₂H₄). Vanadium (V), Tungsten (W), and Titanium (Ti) were coated by the sol-gel method, and then a metal oxide-supported filter was prepared through a calcination process at 350 ℃. A NO_x removal efficiency test was performed for the catalytic ceramic filters with UV light in a humid condition. When graphene oxide (GO) and reduced graphene oxide (rGO) were present on the filter, the NOx removal efficiency was superior to that of the conventional ceramic filter. Most likely, this is due to an improvement in the adsorption properties of NOx molecules on graphene coated surfaces. As the concentration of graphene increased, higher NO_x removal efficiency was confirmed.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.574-581
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• 2022

Nanofibers comprising reduced graphene oxide (rGO) and Mo₂C/Mo₂N nanoparticles (Mo₂C/Mo₂N rGO NFs) were prepared for a functional interlayer of Li-S batteries (LSBs). The well-dispersed Mo₂C and Mo₂N nanoparticles in the nanofiber structure served as active polar sites for efficient immobilization of dissolved lithium polysulfide. The rGO nanosheets in the structure also provide conductive channels for fast ion/electron transport during charging-discharging and ensured reuse of lithium polysulfide during redox reactions through a fast charge transfer process. As a result, the cell assembled with Mo₂C/Mo₂N rGO NFs-coated separator and pure sulfur electrode (70 wt% of sulfur content and 2.1 mg cm^-2 of sulfur loading) showed a stable discharge capacity of 476 mA h g^-1 after 400 charge-discharge cycles at 0.1 C. Furthermore, it exhibited a discharge capacity of 574 mA h g^-1 even at a high current density of 1.0 C. Therefore, we believe that the proposed unique nanostructure synthesis strategy could provide new insights into the development of sustainable and highly conductive polar materials as functional interlayers for high performance LSBs.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.235-235
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• 2012

Reduced graphene oxide (rGO) 물질을 사용하여 전계효과 트랜지스터를 제작하였고 이의 광전기적 특성을 펄스 레이저와 진공 저온 측정을 통하여 분석하였다. 이를 통하여 rGO 소자의 광소자로써의 이용 가능성에 대하여 고찰하였다.

• Journal of the Korean Applied Science and Technology
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• v.35 no.3
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• pp.935-939
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• 2018

3D Printing technology is developing in various prototypes for medical treatment, food, fashion as well as machinery and equipment parts production. 3D printing technology is also able to fully be utilized to other industries in terms of developing its technology which has been reported in many field of areas. 3D printing technology is expected to be used in various applications related to $4^{th}$ industrial revolution such as finished products and parts even it is still carried out in the prototype model. In this study, we have investigated and developed conductive resin for 3d printing application based on reduced graphene oxide(rGO)/Polypyrrole(Ppy) composite and polycaprolactone(PCL) as a biodegradable polymer. The electrical properties and surface morphology of the conductive PCL resin based on therGO/Ppy composite were analyzed by 4point-probe and scanning electron microscope(SEM). The conductive PCL resin based on rGO/Ppy composite is expected to be applicable not only 3D printing, but also electronic materials in other industrial fields.

• Textile Coloration and Finishing
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• v.30 no.2
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• pp.98-106
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• 2018

In this study, graphene oxide(GO) was synthesized by using Hummer's method. Then, GO was used as a additive for epoxy resin nanocomposites that were prepared by mixing Tetraglycidyl diamino diphenyl methane(TGDDM) and hardner(MDEA+M-MIPA). Thermal and mechanical properties of epoxy resin nanocomposites were confirmed by analytical methods such as TG-DTA, DMA, fracture toughness, tensile strength, and flexural strength. The fracture surfaces of epoxy resin nanocomposites with different content of the GO were observed by a Scanning Electron Microscope(SEM). The mechanism for mechanical properties of epoxy resin nanocomposites was analyzed by modeling of nanocomposites with different GO weight. Due to the GO, both the heat resistance and the glass transition temperature of the epoxy resin nanocomposites were improved. Interestingly, when 0.1wt.% of GO was added to the epoxy resin/hardner mixture, the properties of mechanical increased compared with the neat epoxy resin. This results were caused by an aggregation between the GO.