• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.237.1-237.1
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• 2016

Electrical properties of graphene-based field effect transistors (G-FETs) can be degraded in ambient conditions owing to physisorbed oxygen or water molecules on the graphene surface. Passivation technique is one of a fascinating strategy for fabrication of G-FETs, which allows to sustain electrical properties of graphene in the long term without disrupting its inherent properties: transparency, flexibility and thinness. Ironically, despite its importance in producing high performance graphene devices, this method has been much less studied compared to patterning or device fabrication processes. Here we report a novel surface passivation method by using atomically thin self-assembled alkane layers such as C18- NH2, C18-Br and C36 to prevent unintentional doping effects that can suppress the degradation of electrical properties. In each passivated device, we observe a shift in charge neutral point to near zero gate voltage and it maintains the device performance for 1 year. In addition, the fabricated PG-FETs on a plastic substrate with ion-gel gate dielectrics exhibit not only mechanical flexibility but also long-term stability in ambient conditions. Therefore, we believe that these highly transparent and ultra-thin passivation layers can become a promising candidate in a wide range of graphene based electronic applications.

• 한국응용과학기술학회지
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• 제32권3호
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• pp.512-521
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• 2015

PCB 제조에서 photoresist와 Copper Clad Laminate(CCL)의 구리표면과의 부착력을 항상시키기 위하여 사용되는 soft etching제를 제조하기 위하여 과산화수소 사용을 배제하고, 유기산과 유기과산화물을 이용하여 산의 종류, 농도, 에칭시간 등에 따른 구리표면의 에칭속도, 표면 조도, 및 오염도 등을 조사하였다. 또한 에칭 후의 표면의 얼룩을 제거하기 위한 안정제의 최적 배합 및 농도도 확립하였다. 본 연구 결과 유기산의 종류 중에서는 아세트산이 초기 구리 에칭속도가 가장 빨랐으며, 농도가 0.04 M이었을 때 $0.4{\mu}m/min$이였다. 유기과산화물인 APS의 농도는 높을수록 에칭속도가 가장 빨랐으나, 표면 오염이 심각하였다. 안정제 용액의 조성도 표면 오염도에 큰 영향을 주었다. 결과적 0.04 M 아세트산, 0.1M APS에 4 g/L의 안정제(ST-1)를 첨가한 에칭액의 경우 $0.37{\mu}m/min$의 에칭속도와 표면오염이 전혀 없으며, 표면 조도도 가장 우수하였다. 즉, CCL과 photoresist와 접착력을 향상시킬 수 있을 것으로 판단된다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.1118-1125
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• 2009

본 연구는 국내의 초연약지반에 적용 가능한 표층보강재를 이용한 연약지반 표층처리공법을 정립시키기 위한 기초적 연구로서 표층처리공법에 사용되는 보강재의 강성도를 고려한 지 지력산정방법을 제안하는 것을 목적으로 하고 있다. 이를 위하여 직포, 지오그리드, 강봉(대나무 대채재료)을 이용하여 광폭인장시험 및 보강재의 단부 구속조건을 완전구속, 부분구속(3종류)으로 한 21 종류의 실내모형실험을 수행하였다. 실험결과, Terzaghi의 지지력이론식은 직포와 지오그리드와 같은 연성보강재 사용시에는 지지력산정이 적절하나, 대나무 망과 같은 강성도가 큰 재료에 대해서는 강성도를 적절히 표현하지 못하는 것으로 평가되었으며, 초연약지반 표층처리공법의 지지력산정방법을 Terzaghi 지지력이론식을 수정하여 강성도의 영향을 정확히 평가하는 새로운 지지력이론식을 제안하였다.

• 센서학회지
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• 제25권3호
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• pp.178-183
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• 2016

Semiconductor gas sensors based on metal oxide are widely used in a number of applications, from health and safety to energy efficiency and emission control. Nanomaterials including nanowires, nanorods, and nanoparticles have dominated the research focus in this field owing to their large number of surface sites that facilitate surface reactions. Recently, metal oxide hollow structures using soft templates have been developed owing to their high sensing properties with large-area uniformity. Here, we provide a brief overview of metal oxide hollow structures and their gas-sensing properties from the aspects of template size, morphology, and additives. In addition, a gas-sensing mechanism and perspectives are presented.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.423-428
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• 2005

If the load of constructing vehicles during the construction work acts on the road or the ground surface on the soft ground, due to the excess stresses in soils the trafficability of the vehicles influences the constructing efficiency, constructing period and so on. Stress distribution in soils is the very important element to design and to solve the problems of settlement, safety of foundations and trafficability of constructing vehicle in civil engineering. This research represents the comparative estimation of the actual and theoretical measurement on the underground stress of outer layer for each soil after the observation of each top soil layer for its vertical and horizontal stress in (1)homogeneous sand ground (2) weak stratum with the sand soil (3) weak stratum with gravel of the soil model, and it also investigates the effect of subsidence of ground by the repeated load. The underground stress turn out to be different in the value of theoretical and actual measurement after the trial examination of model.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.15.1-15.1
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• 2009

Nano transfer printing and micro contact printing is well known printing method based on soft lithography which uses conformal soft elastomer with designed surface relief structures. Here I introduce another class of novel 3D nanofabrication technique by using the same elastomer but in a different manner. The approach, which we refer to as proximity field nanopatterning, uses the surface-reliefed elastomers as phase masks to pattern thick layers of transparent, photosensitive materials. Aspects of the optics, the materials, and the physical chemistry associated with this method are outlined. A range of 3D structures illustrate its capabilities, and several application examples demonstrate possible areas of use in technologies ranging from microfluidics to photonic materials to density gradient structures for chemical release and high-energy density science.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.310-313
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• 2008

Recently, study on the weak interaction energy between the soft polymer surface and liquid crystals has been a primary topic for new LC device applications. In this paper, to understand the switching property of nematic liquid crystals (LCs) at the interface with a weak anchoring boundary, we investigate experimentally the rotation property of surface nematic director by electric field on non-treated Poly-Methylmethacrylate (PMMA, $T_g=110^{\circ}C$, Sigma Aldrich) film observed under various temperatures including the glass transition temperature ($T_g$) of the polymer layer.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.479-482
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• 2002

The purpose of this paper is to present and discuss some of evaporation and desiccation observed in field experiments. Surface desiccation of dredged material is basically changed by evaporation characteristics which is controlled by weather and ploughing interval, etc. This study shows that ploughing interval is important factors in desiccation of dredged soft clay. A series of field experiments with variation of ploughing interval were carried out to get evaporation effiency and strength increase. In this study, it is proposed that ploughing technique on the total surface area expedites surface desiccation efficiency. Desiccation efficiency is improved when ploughing technique is applied on the surface area.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 추계 학술논문 발표대회
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• pp.80-81
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• 2013

There is the increasing number of constructing soil or structure on the soft ground during public works. Usually cement or slag cement has been the traditional material for surface soil stabilization method. Recently, early strength development properties of hardening agent is required for driving abilities of execution equipment and shortening of the construction time. Therefore, the purpose of this study is to develop the early compressive strength hardening agent for surface soil stabilization. The study was confirmed performance and availability of hardening agent using early strength type cement and industrial by-product minerals through early strength development properties in accordance with water cement ratio, content of hardening agent for soft soil.

• 한국기계가공학회지
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• 제18권11호
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• pp.63-68
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• 2019

The dimensional quality of flexible foams is often difficult to be evaluated through general machine vision inspection methods due to the free deformation of the outer shape. For the evaluation of the dimensions of flexible foams, methods of estimating the size of the product through the expansion rate of the product surface are evaluated. Specimens with various dimensions and surface gratings are prepared, and the degree of surface expansion is measured through machine vision. The correlation, between the measured surface grid size and the actual size of test specimens, is analyzed. We further analyze the correlation between the size of test specimens and the position of the surface grid. This study provides a basis for estimating the actual dimensions of specimens by measuring the surface expansion of flexible foams.