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RISS 인기검색어
- 검색키워드
- 저자 : Jeonghoon Nam(남정훈) (검색결과 3 건)
- 무료
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Synthesis of Alumina-coated Graphite Using Polyvinylpyrrolidone via Sol-Gel Reaction
Jeonghoon Nam(남정훈),Yeongseon Kim(김영선),Kyunghee Kim(김경희),Sung Hyeon Baeck(백성현),Dong Wha Park(박동화),Sang Eun Shim(심상은) 한국고분자학회 2016 폴리머 Vol.40 No.1
흑연은 200~800 W/mK의 우수한 열전도성을 지니고 있으나, 인쇄회로기판의 코팅 재료, 반도체 실장용 접착제의 충전제, 열확산 쉬트와 같은 열전도성 복합재료로 사용하기에 한계가 있다. 이는 전기 전도성에 기인한 것으로, 흑연에 전기 절연성을 부여하기 위하여 폴리비닐피롤리돈(PVP)을 접착력 향상제로 사용하여 알루미나 층을 코팅하였다. 알루미늄 이소프로폭사이드(AIP)를 알루미나의 전구체로 사용하였다. 알루미나 코팅은 염기성 촉매하에서 졸-젤 반응을 통하여 이루어졌다. 제조된 결과물의 모폴로지 변화, 코팅된 알루미나의 양 및 전기 절연성이 조사되었으며, 최적의 알루미나@PVP@흑연의 합성 조건을 찾기 위하여 AIP와 PVP의 양을 변화시켰다. 합성된 알루미나가 코팅된 흑연은 면저항이 1012 ohm/sq으로 전기 절연성을 보유하였다. Although graphite has excellent thermal conductivity of 200-800 W/mK, there are definite limits when applying graphite to thermally conductive materials, such as a coating material for printed circuit boards (PCB), an additive to the adhesive for the assembly of electronic chips, and a filler for thermal spreader pads. The problems are largely attributed to the electrically conductive property. To endow graphite with an electrically insulating property, graphite was coated with a well-grown alumina layer using polyvinylpyrrolidone (PVP) as a cohesive promotor. Aluminum isopropoxide (AIP) was used as the alumina precursor and PVP was used to improve the cohesion between graphite and alumina. An alumina-coating on graphite was conducted by a base-catalyzed sol-gel reaction. The changes in the morphology and the amounts of coated alumina, as well as the electrically insulating properties were investigated. An optimized condition to make alumina@PVP@graphite was determined by changing the amounts of AIP and PVP. The synthesized alumina@PVP@graphite was categorized as an electrical insulator with a high surface resistivity of about 10<SUP>12</SUP> ohm/sq.
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기능적 조음장애아동이 산출한 마찰음의 음향음성학적 특성
남정훈(Nam Jeonghoon),이봉원(Yi Bong-won) 한국음성학회 2010 말소리와 음성과학 Vol.2 No.4
The purpose of this study was to compare the acoustic properties of fricatives, /ㅅ, ㅆ/ produced by children with functional articulation disorder and normal children (N=20, aged 6-7). All subjects showed significant differences in both the length of friction intervals and breathing intervals of fricatives according to the changes in the environment presented within each group. However, there is a difference in the extent of variation in length between the two groups. This means that children with functional articulation disorder have greater difficulty in adjusting fricative noises according to changes in the CV · VCV environment than normal children.
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Mechanical Properties of Silica-coated Multi-walled Carbon Nanotube/Epoxy Composites
Kyunghee Kim(김경희),Yeongseon Kim(김영선),Jeonghoon Nam(남정훈),Sung-Hyeon Baeck(백성현),Dong Wha Park(박동화),Sang Eun Shim(심상은) 한국고분자학회 2016 폴리머 Vol.40 No.1
다중벽 탄소 나노튜브(MWCNTs)/에폭시 복합체의 기계적 강도와 전기 절연성을 증가시키기 위하여, tetraethyl orthosilicate(TEOS)를 전구체로 사용한 1 단계 졸-젤 반응을 통하여 다중벽 탄소 나노튜브(MWCNTs)를 실리카 층으로 코팅하였다. MWCNTs 표면을 화학적으로 개질하지 않고 폴리에틸렌이민을 커플링제로 사용하여 실리카로 균일하게 코팅하였다. 실리카 코팅된 MWCNTs 및 순수한 MWCNTs를 충전제로 사용하여 제조된 복합체의 기계적 특성, 열적 특성, 전기적 성질을 관찰하였다. 에폭시 사슬들은 MWCNTs 표면의 실리카 층에 강하게 속박되어, 실리카 층은 MWCNTs에 전기 절연막을 형성하였다. 결과적으로, 실리카 코팅된 MWCNTs가 충전된 에폭시 복합체의 기계적 물성 및 전기저항이 증가하였다. Multi-walled carbon nanotubes (MWCNTs) were coated with silica layers via a one-step sol-gel process with tetraethyl orthosilicate (TEOS) as a silica precursor to enhance the mechanical strength and electrical resistivity of MWCNTs-filled epoxy composites. The MWCNTs were coated uniformly with silica using polyethyleneimine as a coupling agent without chemical modification of the surface of the MWCNTs. The silica-coated MWCNTs were used as a filler in the epoxy. The epoxy composites filled with the raw and silica-coated MWCNTs were prepared and their properties were examined in terms of mechanical, thermal and electrical properties. The epoxy chains were bound strongly to the silica layer on the surface of the MWCNTs, and the silica layer provided the MWCNTs with electrically insulating barriers. As a result, the silica-coated MWCNTs-filled epoxy composites showed improved mechanical strength and electrical resistivity.
ScienceON
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