• 한국전기전자재료학회논문지
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• 제25권8호
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• pp.639-645
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• 2012

Embossed $TiO_2$ thin films with high surface areas are achieved using soft-templates composed of monolayer polystyrene beads. The form of links between the beads in the templates is controlled by varying the $O_2$ plasma etching time on the templates, resulting in various templates with close-linked, nano-linked, and isolated beads. Room-temperature deposition of $TiO_2$ on the plasma-treated templates and calcination at $550^{\circ}C$ result in embossed films with tailored links between anatase $TiO_2$ hollow hemispheres. Although all the embossed films have similar surface areas, the sensitivity of films with nano-linked $TiO_2$ hollow hemispheres to 500 ppm CO and ethanol gases are much higher than that of films with close-linked and isolated hollow hemispheres, and the detection limits of them are as low as 0.6 ppm for CO and 0.1 ppm for ethanol. The strong correlation of sensitivity with the form of links between hollow hemispheres reveals the critical role of potential barriers formed at the links. The facile, large-scale, and on-chip fabrication of embossed $TiO_2$ films with nano-linked hollow hemispheres on Si substrate and the high sensitivity without the aid of additives give us a sustainable competitive advantage over various methods for the fabrication of highly sensitive $TiO_2$-based sensors.

• 한국정밀공학회지
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• 제27권1호
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• pp.18-24
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• 2010

Efforts to obtain more efficient coupling of light from a laser diode to a single mode fiber have continued for various applications such as links for optical fiber communication systems. In TO-can package, configuration of optimized aspherical lens is bi-aspheric and its diameter is 2.4mm. We designed and fabricated aspherical coupling lens by means of glass molding technique under consideration of glass shrinkage. By controlling the aspherical profile error and surface roughness which were below 90nm and 10nm, respectively, we obtained the low coupling loss, 5.40dB, which was able to use for coupling a single mode fiber to laser diode.

• 통합자연과학논문집
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• 제3권2호
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• pp.96-102
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• 2010

It is still controversial where the improved stability of n-octadecyltriethoxysilane self-assembled monolayer (OTE SAM) on plasma-pretreated mica surface exactly originates from. To date, it has been well known that the extensive cross-polymerization between silane headgroups is a crucial factor for the outstanding mechanical strength of the monolayer. However, this study directly observed that the stability comes not only from the cross-links but also, far more importantly, from the direct chemical bonds between silane headgroups and mica surface. To observe this phenomenon, n-octadecyltrichlorosilane monolayers were self-assembled on both untreated and plasma treated mica surfaces, and their adhesion properties at various stress conditions and force profiles in pure water were investigated and compared through the use of the surface forces apparatus technique. It revealed that, in pure water, there is a substantial difference of stability between untreated and plasma treated cases and the plasma treated surface is mechanically much more stable. In particular, the protrusion behavior of the monolayer during contact repetition experiment was always observed in the untreated case, but never in the plasma treated case. It directly demonstrates that the extensive chemical bonds indeed exist between silane head-groups and plasma treated mica surface and dramatically improve the mechanical stability of the OTE monolayer-coated mica substrate.

• 통합자연과학논문집
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• 제3권2호
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• pp.89-95
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• 2010

It is still controversial where the improved stability of n-octadecyltriethoxysilane self-assembled monolayer (OTE SAM) on plasma-pretreated mica surface exactly originates from. To date, it has been well known that the extensive cross-polymerization between silane head-groups is a crucial factor for the outstanding mechanical strength of the monolayer. However, this study clearly showed that the stability comes not only from the cross-links but also, far more importantly, from the direct chemical bonds between silane headgroups and mica surface. To examine this phenomenon, n-octadecyltrichlorosilane monolayers were self-assembled on both untreated and plasma treated mica surfaces, and their adhesion properties at various physical conditions (relative humidity, high stress, and contact repetition) were investigated and compared through the use of the surface forces apparatus technique. It revealed that, in highly humid conditions (>90%RH), there is a substantial difference of stability between untreated and plasma treated cases and the plasma treated surface is mechanically much more stable. It obviously proves that the extensive chemical bonds indeed exist between silane head-groups and plasma treated mica surface and dramatically improve the mechanical stability of the OTE monolayer-coated mica substrate.

• 한국표면공학회지
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• 제42권4호
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• pp.179-185
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• 2009

Diamond-like carbon(DLC) films were deposited by linear ion source(LIS)-physical vapor deposition method changing the anode voltages from 800 V to 1800 V, and characteristics of the films were investigated using residual stress tester, nano-indentation, micro raman spectroscopy, scratch tester and Field Emission Scanning Electron Microscope(FE-SEM). The results showed that the residual stress and hardness increased with increasing the ion energy up to anode voltage of 1400 V. It was also found that the content of $SP^3$ carbon increased with increasing the anode voltage $SP^3/SP^2$ ratio through investigation of $SP^3/SP^2$ ratio by the micro-raman analysis. From these results, it can be concluded that the physical properties of DLC films such as residual stress and hardness are increased with increasing the anode voltage. These results can be explained that 3-dimensional cross-links between carbon atoms and Dangling bond are enhanced and the internal compressive stress also increased with increasing the anode voltage. The optimal anode voltage is considered to be around 1400 V in these experimental conditions.

• 인터넷정보학회논문지
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• 제20권1호
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• pp.17-24
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• 2019

2016년 세계경제포럼(WEF)에서 4차산업혁명이 소개된 이래 사물인터넷, 인공지능, 빅데이터, 5G, 클라우드 컴퓨팅, 3D/4D 프린팅, 로보틱스, 나노기술, 바이오 공학 등 다양한 분야에서 이런 기술을 활용한 제품과 비즈니스가 빠르게 확대되어 왔다. 사물인터넷 중에서는 웨어러블 디바이스가 최종고객을 대상으로 활용되는 선도적 적용분야로 인식되고 있다. 본 연구의주요 목적은 활동량 측정기에 대해서 고객의 욕구를 파악하고, 이를 마케팅 믹스와 연계시킨 제1차 연구에 기반하여 제2차 연구를 수행하고 이 결과를 제1차 연구결과와 비교하는 종단연구이다. 더불어서 미래 활동령 측정기 개발을 위한 잠재욕구를 파악하는 것이다. 이를 위해서 2018년 5월 대학생들을 대상으로 서베이가 수행되었으며 이용특성에 관한 주요변수에 대해서 ANOVA 등 실증연구가 이루어졌다. 또한 제1차 연구와는 달리 잠재욕구에 대한 분석결과를 단어구름기법을 사용하여 시각화하였다. 제품 가격 유통 촉진 등의 마케팅 믹스에 기반을 둔 종단연구결과에 따르면 현재 활동량 측정기는 도입기에서 성장기로 이전하고 있으며, 마케팅 믹스 각각에 대한 변화를 발견할 수 있었다. 연구결과는 학계뿐 아니라 사물인터넷 기반의 디바이스를 개발하려는 개발자에게 고객의 욕구에 기반 개발과 관련하여 시사점을 제공한다.