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하이브리드 블라인드 접합을 이용한 이종소재 염수분무 특성에 관한 연구
정윤수(Jung Yoonsoo),김상유(Kim Sangyu),김재열(Kim Jaeyeol) 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.8
연비향상 및 CO₂ 배출량 감축에 크게 영향을 미치는 것은 자동차 중량이다. 완성차 업체에서는 그 중요성을 인식하고, 오래전부터 경량화에 대처해 왔다. 최근 미세먼지 등 대기오염이 심각해짐에 따라 배기가스 규제가 단계적으로 강화되고 있어 경량화에 의한 연비 향상은 이전보다 더욱 더 중요시 되고 있다. 자동차 산업에서 알루미늄 합금과 함께 경금속 적용의 증가로 재료의 따라 가장 적합한 용접 및 접합 방법을 선택해야 한다. 본 연구에서는 하이브리드 블라인드 접합을 이용하여 이종소재 시험편의 염수분무 특성을 분석하고자 한다. 하이브리드 블라인드 접합은 블라인드 리벳과 접착제를 함께 사용한 접합법이다. 이종소재 금속간 전위차이에 의한 갈바닉 부식이 예상되어 염수분무 시험을 통한 부식 시험을 진행하여 시험편의 외관을 육안으로 확인하고, 접합 단면을 FE-SEM 이미지를 통해 분석하였다. 더불어 시험편 조합별로 2회씩 인장전단 테스트를 진행하여 인장강도를 평가하였다.
Sang Ho Rha,Jisim Jung,Yoonsoo Jung,Yoon Jang Chung,Un Ki Kim,Eun Suk Hwang,Byoung Keon Park,Tae Joo Park,Jung-Hae Choi,Cheol Seong Hwang IEEE 2012 IEEE transactions on electron devices Vol.59 No.12
<P>The transmission-line method (TLM) was adopted to clarify the causes of device performance variation according to the source/drain metal electrode and device structure of a thin-film transistor using an amorphous indium-gallium-zinc-oxide channel. Using the TLM, the channel characteristics independent of contact resistance were extracted for the two different contact metals, i.e., Ti and Mo. Based on these results, the mobility characteristics were compared in terms of device scaling and contact structure in the source/drain overlap region. In addition, the transport characteristics according to the contact structure of the source/drain metal electrode were investigated in detail and reproduced using the simulation model.</P>
Multifaceted adsorption of α-cyano-4-hydroxycinnamic acid on silver colloidal and island surfaces
Jung, Dawoon,Jeon, Kooknam,Yeo, Juhyun,Hussain, Shafqat,Pang, Yoonsoo Elsevier 2017 APPLIED SURFACE SCIENCE - Vol.425 No.-
<P><B>Abstract</B></P> <P>The surface adsorption of organic nitrile compounds on the silver colloidal and island surfaces has been studied using surface-enhanced Raman scattering (SERS). α-Cyano-4-hydroxycinnamic acid (CHCA) with nitrile and carboxyl groups shows various surface adsorption on the silver surfaces. In acidic conditions, the surface adsorption of CHCA via the nitrile group with a more or less tilted geometry to the surface was found. When the solution pH increases, the carboxylate and nitrile groups of deprotonated CHCA participate in the surface adsorption, whereas the molecular plane of CHCA becomes more parallel to the surface. The ν(CN) band in SERS of CHCA is the indicator of the surface adsorption geometry. The strongly red-shifted and broadened ν(CN) band in SERS represents the surface adsorption via π-electrons of the CN bond (side-on geometry; π-coordination). Nitriles adsorbed on the surface via the nonbonding electron pair of the nitrogen atom (end-on geometry; σ-coordination) often cause the blue-shifts and small band broadening in ν(CN) in SERS. The surface adsorption geometry of organic nitriles based on many previous experimental results was further confirmed by the surface adsorption of CHCA on the silver island surfaces and dinitrile compounds on the silver colloidal surfaces.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Organic nitriles show two distinct adsorption geometries on silver nanosurfaces. </LI> <LI> Surface adsorption via nitrile and carboxylate groups showed strong pH dependence. </LI> <LI> SERS is a powerful tool for the molecular structure of surface-adsorbed species. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Kim, Jung Han,Kim, Jong Gu,Song, Junghyun,Bae, Tae-Sung,Kim, Kyou-Hyun,Lee, Young-Seak,Pang, Yoonsoo,Oh, Kyu Hwan,Chung, Hee-Suk Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.436 No.-
<P><B>Abstract</B></P> <P>We investigated the semiconductor-catalyzed formation of semiconductor nanowires (NWs) – silver sulfide (Ag<SUB>2</SUB>S)-catalyzed zinc sulfide (ZnS) NWs – based on a vapor-liquid-solid (VLS) growth mechanism through metal-organic chemical vapor deposition (MOCVD) with a Ag thin film. The Ag<SUB>2</SUB>S-catalyzed ZnS NWs were confirmed to have a wurtzite structure with a width and length in the range of ∼30 nm to ∼80 nm and ∼1 μm, respectively. Using extensive transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) analyses from plane and cross-sectional viewpoints, the ZnS NWs were determined to have a c-axis, [0001] growth direction. In addition, the catalyst at the top of the ZnS NWs was determined to consist of a Ag<SUB>2</SUB>S phase. To support the Ag<SUB>2</SUB>S-catalyzed growth of the ZnS NWs by a VLS reaction, an in situ heating TEM experiment was conducted from room temperature to 840 °C. During the experiment, the melting of the Ag<SUB>2</SUB>S catalyst in the direction of the ZnS NWs was first observed at approximately 480 °C along with the formation of a carbon (C) shell. Subsequently, the Ag<SUB>2</SUB>S catalyst melted completely into the ZnS NWs at approximately 825 °C. As the temperature further increased, the Ag<SUB>2</SUB>S and ZnS NWs continuously melted and vaporized up to 840 °C, leaving only the C shell behind. Finally, a possible growth mechanism was proposed based on the structural and chemical investigations.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ag<SUB>2</SUB>S catalyzed ZnS nanowires were synthesized using a VLS method. </LI> <LI> Chemical and structural analyses were performed from the plane and cross-sectional viewpoints. </LI> <LI> An in situ heating TEM experiment was conducted from room temperature to 840 °C. </LI> <LI> A possible growth mechanism was suggested based on the structural and chemical investigation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
이종 경량소재 적용 Fender Apron 최적설계에 관한 연구
이경일(Gyungil Lee),김재열(Jaeyeol Kim),정윤수(Yoonsoo Jung),김상유(Sangyu Kim),이상헌(Sangheon Lee),최현범(Hyunbum Choi),김상두(Sangdog Kim) 한국자동차공학회 2019 한국자동차공학회 학술대회 및 전시회 Vol.2019 No.11
At present, the vehicle market has developed environment-friendly vehicles to comply with fuel economy regulations and exhaust regulations stricter and stricter over time. Many studies have been conducted to improve travel performance and fuel economy of the environment-friendly vehicles, and vehicle manufacturers study how to manufacture light-weight vehicles for improving fuel economy for both existing vehicles and environment-friendly vehicles. Exemplary light-weight vehicle technologies include optimal design of vehicle body structure which is a light-weight vehicle method by changing component shapes or layout to optimize the vehicle body structure, and the new process technology for using new light-weight and very strong materials, not typical materials, to manufacture light-weight vehicles. This study aims at optimal design of vehicle body structure using multi-materials for the Fender-Apron which is a important frame member for the external front side of a vehicle body by conducting FEA (Finite Element Analysis) and multi-material bonding.