• 항공우주산업기술동향
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• 제6권1호
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• pp.90-98
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• 2008

나노기술(NT, Nanotechnology)은 분자 및 원자 수준에서 물질을 제작 및 가공할 수 있는 초극미세기술을 의미하며, 재료, 물리, 전자 등의 기존의 기술 분야들을 융합하여 새로운 기술 영역을 구축하는 학제간 연구(Interdisciplinary)가 필요한 분야이다. 국내에서는 탄소나노튜브가 향후 반도체를 견인할 10대 신성장동력 미래기술로 선정되어 활발한 연구가 이루어지고 있다. 나노기술이 미소과학 분야라면 우주기술(ST, Space Technology)는 거대 복합과학 분야를 대표하는 기술로서 기계, 재료, 전자, 통신 등의 기술을 활용하는 시스템 기술이다. 우리나라의 우주개발은 선진국 보다 비록40년 가량 늦었지만 15년 남짓한 기간에 기술자립화 단계로 나아가는 비약적인 성과를 보여주고 있다. 전남 고흥에 나로우주센터가 완공되면 우리 땅에서, 우리 위성을, 우리 발사체로 발사할 수 있게 된다. 나노기술분야는 나노재료, 나노전자, 나노제조 등 매우 광범위하므로 우주기술 개발을 위한 제한된 자원의 견지에서, 비용 대비 성능이 가장 우수하게 평가되는 나노 기술적 구성요소들에 집중하는 것이 필요하다. 본 논문에서는 미국 NASA에서 수행중인 나노기술 개발현황과 유럽의 9차 나노포럼에서 보고한 우주항공분야의 나노기술을 기초로, 현재 우주항공선진국에서 수행중인 개발 현황을 정리하였다. 성능 나노기술의 도움으로 이전에는 불가능하였던 우주 기술이 현실로 다가오고 있는바, 우주개발의 경쟁력을 얻기 위해서는 나노기술을 접목해야만 한다는 것을 알 수 있다. 우리나라는 국가우주개발중장기계획에 따라 2025년 달탐사 착륙선을 개발할 계획이므로, 나노기술을 적극적으로 활용하여 선진국수준의 기술을 확보해야 할 것이다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제5권2호
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• pp.131-135
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• 2005

The effect of different surface passivation films on blue or green (465-505 nm) InGaN/GaN multi-quantum well light-emitting diodes (LEDs) die were examined. $SiO_2$ or $SiN_x$ deposited by plasma enhanced chemical vapor deposition, or $Sc_2O_3$ or MgO deposited by rf plasma enhanced molecular beam epitaxy all show excellent passivation qualities. The forward current-voltage (I-V) characteristics were all independent of the passivation film used, even though the MBE-deposited films have lower interface state densities ($3-5{\times}10^{12}\;eV^{-1}\;cm^{-2}$) compared to the PECVD films (${\sim}10^{12}\;eV^{-1}\;cm^{-2}$), The reverse I-V characteristics showed more variation, hut there was no systematic difference for any of the passivation films, The results suggest that simple PECVD processes are effective for providing robust surface protection for InGaN/GaN LEDs.

• BMB Reports
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• 제53권11호
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• pp.594-599
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• 2020

Lin28a has diverse functions including regulation of cancer, reprogramming and regeneration, but whether it promotes injury or is a protective reaction to renal injury is unknown. We studied how Lin28a acts in unilateral ureteral obstruction (UUO)-induced renal fibrosis following unilateral ureteral obstruction, in a mouse model. We further defined the role of Lin28a in transforming growth factor (TGF)-signaling pathways in renal fibrosis through in vitro study using human tubular epithelium-like HK-2 cells. In the mouse unilateral ureteral obstruction model, obstruction markedly decreased the expression of Lin28a, increased the expression of renal fibrotic markers such as type I collagen, α-SMA, vimentin and fibronectin. In TGF-β-stimulated HK-2 cells, the expression of Lin28a was reduced and the expression of renal fibrotic markers such as type I collagen, α-SMA, vimentin and fibronectin was increased. Adenovirus-mediated overexpression of Lin28a inhibited the expression of TGF-β-stimulated type I collagen, α-SMA, vimentin and fibronectin. Lin28a inhibited TGF-β-stimulated SMAD3 activity, via inhibition of SMAD3 phosphorylation, but not the MAPK pathway ERK, JNK or p38. Lin28a attenuates renal fibrosis in obstructive nephropathy, making its mechanism a possible therapeutic target for chronic kidney disease.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.84-87
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• 2001

A demand for the aggregates is increasing in the field of civil and architectural industry and so on. In these industries, the particle size and shape of aggregates are important factors and especially spherical or rounded particles are desired. In Japan, waste glass is used as one of the aggregate materials for the pavement or the construction. In this study based on the frictional action of material on each other, an autogenous grinding of silica glass with a stirred mill were carried out in order to eliminate flakelike or squarish particles and get spherical or rounded ones for aggregate materials. The autogenous grinding experiments were conducted by applying loads to the particle layer of silica glass. The particle shape was evaluated by the shape index, N/T and the degree of circularity, Ψ$_{ci}$ . The unfractured particles (20~13mm) were evaluated by N/T and Ψ$_{ci}$ , and the products (finer than 10${\mu}{\textrm}{m}$) by Ψ$_{ci}$ . As a result, N/T of the unfractured particles decreased with an increase of grinding time. Ψ$_{ci}$ of the unfractured particles and the products increased with an increase of grinding time (; progress of grinding), and became almost constant in the long time grinding. These tendencies were not changed by the applied load on the particle layer, but the limit value of Ψ$_{ci}$ at the products were varied with the applied load.plied load.

• BMB Reports
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• 제50권1호
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• pp.43-48
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• 2017

Accumulation of tissue macrophages is a significant characteristic of disease-associated chronic inflammation, and facilitates the progression of disease pathology. However, the functional roles of these bone marrow-derived macrophages (BMDMs) in aging are unclear. Here, we identified age-dependent macrophage accumulation in the bone marrow, showing that aging significantly increases the number of M1 macrophages and impairs polarization of BMDMs. We found that age-related dysregulation of BMDMs is associated with abnormal overexpression of the anti-inflammatory interleukin-10. BMDM dysregulation in aging impairs the expression levels of pro-inflammatory cytokines and genes involved in B-cell maturation and activation. Phagocytosis of apoptotic Jurkat cells by BMDMs was reduced because of low expression of phagocytic receptor CD14, indicating that increased apoptotic cells may result from defective phagocytosis of apoptotic cells in the BM of aged mice. Therefore, CD14 may represent a promising target for preventing BMDM dysregulation, and macrophage accumulation may provide diagnostic and therapeutic clues.

• 소성∙가공
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• 제17권8호
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• pp.633-642
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• 2008

It's important to measure quantitative properties about thermal-nano behavior of polymer for producing high quality components using Nanoimprint lithography process. Nanoscale indents can be used to make the cells for molecular electronics and drug delivery, slots for integration into nanodevices, and defects for tailoring the structure and properties. In this study, formability of polymethylmetacrylate(PMMA) and polycarbonate(PC) were characterized Polymer has extreme variation in thermo mechanical variation during forming high temperature. Because of heating the polymer, it becomes softer than at room temperature. In this case it is particularly important to study high temperature-induced mechanical properties of polymer. Nanoindenter XP(MTS) was used to measure thermo mechanical properties of PMMA and PC. Polymer was heated by using the heating stage on NanoXP. At CSM(Continuous Stiffness Method) mode test, heating temperature was $110^{\circ}C,120^{\circ}C,130^{\circ}C,140^{\circ}C$ and $150^{\circ}C$ for PMMA, $140^{\circ}C,150^{\circ}C,160^{\circ}C,170^{\circ}C$ and $180^{\circ}C$ for PC, respectively. Maximum indentation depth was 2000nm. At basic mode test, heating temperature was $90^{\circ}C$ and $110^{\circ}C$ for PMMA, $140^{\circ}C,160^{\circ}C$ for PC. Maximum load was 10mN, 20mN and 40mN. Also indented pattern was observed by using SEM and AFM. Mechanical properties of PMMA and PC decreased when temperature increased. Decrease of mechanical properties from PMMA went down rapidly than that of PC.

• International journal of advanced smart convergence
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• 제5권4호
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• pp.15-20
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• 2016

When a virtual sound source for 3D auditory system is reproduced by a linear loudspeaker array, listeners can perceive not only the direction of the source, but also its distance. Control over perceived distance has often been implemented via the adjustment of various acoustic parameters, such as loudness, spectrum change, and the direct-to-reverberant energy ratio; however, there is a neglected yet powerful cue to the distance of a nearby virtual sound source that can be manipulated for sources that are positioned away from the listener's median plane. This paper address the problem of generating binaural signals for moving sources in closed or in open environments. The proposed perceptual enhancement algorithm composed of three main parts is developed: propagation, reverberation and the effect of the head, torso and pinna. For propagation the effect of attenuation due to distance and molecular air-absorption is considered. Related to the interaction of sounds with the environment, especially in closed environments is reverberation. The effects of the head, torso and pinna on signals that arrive at the listener are also objectives of the consideration. The set of HRTF that have been used to simulate the virtual sound source environment for 3D auditory system. Special attention has been given to the modelling and interpolation of HRTFs for the generation of new transfer functions and definition of trajectories, definition of closed environment, etc. also be considered for their inclusion in the program to achieve realistic binaural renderings. The evaluation is implemented in MATLAB.

• Korean Chemical Engineering Research
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• 제46권4호
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• pp.647-659
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• 2008

콜로이드는 거시적으로 균일한 성질을 갖는 입자분산계이다. 콜로이드 입자는 다양한 입자분산계의 모델로서 많은 기초연구가 이루어져 왔을 뿐만 아니라, 산업적으로 다양하게 응용이 되었다. 최근에는 나노-바이오 관련 연구에 적용되어 새롭게 각광을 받고 있는 나노 소재중 하나이다. 본 총설에서는 입자 분산계의 정의 및 분류에 대해 간략히 기술하고, 나노-바이오 응용을 위한 표면 성질 및 표면 개질방법에 대해 다룰 것이다. 또한, 기존의 구형의 입자분산계에서 더 나아가, 모양과 크기가 제어된 입자 분산계의 합성에 관한 최근 결과를 소개하였다. 마지막으로, 콜로이드 입자의 나노-바이오 응용분야로서, 금속 콜로이드 잉크와, 3차원 콜로이드 결정을 활용한 나노-바이오 센서, 및 2차원 콜로이드 구조를 이용한 패턴제작과 응용 연구에 대해 살펴보았다.

• 한국재료학회지
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• 제11권3호
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• pp.185-190
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• 2001

(hfac)Cu(I)L구리 1가 전구체의 경우 L의 종류에 따라 여러 화합물이 존재하며 L이 전구체의 특성 및 증착에 미치는 영향을 규명하였다. 이때 중성리간드는 ATMS(allytrimethylsilane), VTMS(vinyltri-methylsilane), VCH(vinylcyclohexane), MP (4-methyl-1-pentene), ACP(allylcyclopentane), DMB (3,3-dimethyl-1-butene) 등의 alkene류이었다 hfacCu(I)L 전구체는 TG-DSC 분석에서 관찰된 Cu(I)-L 분해 온도가 낮으면 $100^{\circ}C$ 이하의 저온 증착이 가능하였고 저온에서 낮은 박막 비저항 값을 얻을 수 있었다. 또한 이 분해온도가 높은 전구체 일수록 열적으로 안정함을 일정 시간 가열평가를 통해 알 수 있었다. 약 $125~175^{\circ}C$ 증착온도에서는 중성리간드의 종류에 무관하게 증착된 구리 박막의 비저항값이 거의 비슷하였고 약 $226^{\circ}C$ 이상의 증착온도에서는 박막의 비저항이 중성리간드의 분자량의 크기에 비례하여 증가하였다. 전구체의 증기압은 중성리간드의 끓는점과 가장 밀접한 관계가 있으며 중성리간드의 끓는점이 낮으면 낮을수록 증기압은 높았다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.111-114
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• 1999

Electroluminescence(EL) devices based on organic thin films have been attracted lots of interests in large-area light-emitting display. In this stuffy, an emissive layer was fabricated using Langmuir-Blodgett(LB) technique in organic light-emitting (OLEDs). This emissive organic material was synthesized and named PECCP[poly(3.6-N-2-ethylhexyl carbazolyl cyanoterephthalidene)] which has a strong electron donor group and an electron acceptor group in main chain repeated unit. This material has good solubility in common organic solvents such as chloroform. THF, etc, and has a good stability in air. The Langmuir-Blodgett(LB) technique has the advantage of precise control of the thickness down to the molecular scale, In particular, by varying the film thickness it is possible to investigate the metal/polymer interface. Optimum conditions for the LB film deposition are usually determined by investigating a relationship between a surface pressure $\pi$ and an effective are A occupied by one molecule on the subphase. The LB films were deposited on an indium-tin-oxide(ITO) glass at a surface pressure of 10 mN/m and dipping speed of 12 mm/min after spreading PECCP solution on distilled water surphase at room temperature, Cell structure was ITO/PECCP LB film/Alq$_3$/Al. We considered PECCP as a hole -transport layer inserted between the emissive layer and ITO. We also used Alq$_3$ as an emissive layer and an electron transport layer. We measured current-voltage(I-V) characteristics, UV/visible absorption, PL spectrum and EL spectrum of the OLEDs.