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Performance Evaluation of Atomization-Based Uniform Spray Coating for 3D Scanning
Jungsoo Nam(남정수),Benzad Valinasab(발리나사브 베자드),Martin B. G. Jun(전병국) Korean Society for Precision Engineering 2017 한국정밀공학회지 Vol.34 No.10
Three-dimensional (3D) scanning processes have been applied to a wide range of manufacturing industries for inspection and reverse engineering. Especially, optical scanning method is used mostly as a non-contact scanning technique in manufacturing field. However, it can be influenced from surface characteristics such as transparency and reflectivity. To resolve these problems, various coating techniques have been studied for years. Among them, atomization-based coating method is one of the key technologies to change its characteristics before scanning the objects. In this study, atomizationbased spray coating system is developed for producing a uniform thin layer. Then, a series of experiments are conducted to evaluate the coating performance with the developed coating system. As a result, after coating the surface of transparent and shiny target objects: glass slide, colour sample, cell cover, and clutch lever, 3D scanning results show that a uniform coating of target objects is significantly improved. Its coating thickness is less than 1 μm which means that it is important to keep the geometry unchanged of the part.
고분자전해질 연료전지 분리판을 위한 그라핀이 코팅된 스테인리스강의 특성
남대근(Nam, Daeguen),김정수(Kim, Jungsoo),최창용(Choi, Changyong),박영도(Park, Youngdo),오원태(Oh, Weontae) 한국신재생에너지학회 2011 한국신재생에너지학회 학술대회논문집 Vol.2011 No.05
연료전지 분리판은 연료, 공기, 수분이 흐를 수 있는 채널들이 포함되어 있으며, 전지들에 의해서 생산되는 전류를 흐르게 할 수 있는 전기전도성을 가져야 할 필요가 있다. 일반적인 금속판들은 연료전지 스택 내의 산성 분위기에 존재해야 하기 때문에 표면 부식이 쉽게 발생한다. 그라핀(graphene)은 우수한 전기전도성을 가지고 있을뿐만 아니라 물리화학적 내식성 및 내구성을 가지고 있어 연료전지 분리판으로서 응용이 가능할 것으로 판단된다. 본 연구에서는 일반적으로 널리 사용하고 있는 스테인리스강(stainless steel)을 모재로 사용하였으며, 그라핀을 전기분무법(electro spray coating)으로 코팅하여 스테인리스강의 내식성 및 전기전도성을 동시에 향상시키고자 하였다. 그라핀은 에탄올을 용매로 사용하여 분산하였으며, 분산제로 소량의 다이페닐다이에톡시실란(diphenyldiethoxysilane)을 첨가하여 코팅용액을 제작하였다. 코팅공정은 15kV 전압을 가하여 1시간동안 코팅을 진해하였으며, 그라핀-스테인리스강 모재의 미세구조를 전자현미경과 광학현미경을 통하여 관찰하였다. 또한 X-선 회절분석법을 이용하여 그라핀의 결정구조를 분석하였다. 한편 스택의 내부와 유사한 산화성 분위를 모사하기 위해 80?C의 0.1N H₂SO₄+2ppm;F^- 용액에서 내식성 실험을 수행하였고, 면간접촉저항도 측정하였다. 그라핀이 코팅된 스테인리스강 시편은 고분자전해질 연료전지 분리판의 요구조건을 만족하였으며, 연료전지 분리판으로서의 적용가능성을 확인하였다.
Electrochemical Oxidations of Alcohols on Platinum/Carbon Nanotube Composites
Kim, Jungsoo,Nam, Dae-Geun,Oh, Weontae The Korean Institute of Electrical and Electronic 2013 Transactions on Electrical and Electronic Material Vol.14 No.3
Composites of platinum and multiwalled carbon nanotubes (MWNTs) were prepared in various reduction conditions and characterized using cyclic voltammetry. The MWNTs were functionalized with carboxylic acid and/or hydroxyl groups in acidic solutions prior to the formation of MWNT-Pt composites. Platinum nanoparticles were deposited onto the chemically-oxidized MWNTs in 1-propanol and 1,3-propanediol. The reduction of Pt precursors in other solutions could induce differences in their morphologies in composite thin films. The morphologies of MWNTs with Pt deposited were dependent on the reduction solutions, and the electrocatalytic activities on alcohols changed accordingly. The electrochemical activities of the as-prepared MWNT-Pt thin films on common alcohols such as methanol and ethanol were investigated.
Characterization of Graphite Oxide Reduced by Thermal and/or Chemical Treatments
Kim, Jungsoo,Nam, Dae-Geun,Yeum, Jeong Hyun,Suh, Sungbu,Oh, Weontae The Korean Institute of Electrical and Electronic 2015 Transactions on Electrical and Electronic Material Vol.16 No.5
Reduced graphite oxides (rGOs) were prepared by the common graphite oxidation method and the subsequent reductions. The reduction of graphite oxides (GOs) was conducted chemically and/or thermally. To further reduce the as-prepared rGOs, GOs were treated with chemical/thermal reductions or thermal/chemical reductions, in which the reduction sequence was also considered. The structural changes of as-prepared rGOs, depending on reduction methods, were investigated by X-ray diffraction analyses, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. In addition, we discuss the structural change of the rGOs and their closely related physical and electrical properties, such as thermogravimetry, nitrogen adsorption isotherm, and sheet resistance.
Thermal Properties of epoxy composites with silicon carbide and/or graphite
Kim, Jungsoo,Kim, Yang Do,Nam, Dae Geun,Bae, Jong-Seong,Yeum, Jeong Hyun,Oh, Weontae 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol. No.
<P>Epoxy composites were fabricated with a filler of silicon carbide (SiC) and/or graphite to improve the thermal conductivity and thereby enhance the transfer of the heat from the light-emitting diode (LED) to the heat sink. The two fillers (SiC and graphite) were each added either separately, within a content range of 10 - 50 wt.%, or together to give a combined total content of 40 - 60 wt.%. The effect of the filler addition on the thermal and the mechanical properties of the epoxy composites was examined. The filler-induced change on the structural properties was investigated by using a morphological analysis of the epoxy composites, and the thermal conductivity was analyzed by measuring the thermal diffusivity, heat specific, and density. To confirm the adhesive property with aluminum, which is mostly used as the heat sink material were tested, the mechanical properties by using a bonding test with a modified tensile test. The thermal and the mechanical properties were improved with increasing filler content in the epoxy composites. In the case of combined filler addition, graphite was more effective than SiC in increasing the thermal properties. However, excessive filler addition reduced the epoxy's natural adhesive property and hence degraded the mechanical properties.</P>