• 접착 및 계면
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• 제24권4호
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• pp.136-142
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• 2023

본 연구에서는 실리카원으로 Tetraethyl orthosilicate (TEOS)를 사용하고 주형으로 트리블럭 공중합체(P123)를 사용하여 산성 조건에서 자기조립 방법과 수열합성 과정을 거쳐서 잘 배열된 육방체 구조의 메조세공 배열구조를 가지는 다공성 실리카 물질(Surfactant-extracted SBA-15)을 합성하였다. Surfactant-extracted SBA-15는 약 980 nm의 크기를 가지는 짧은 로드의 입자 모양을 보여주었다. 그리고 표면적과 세공 직경은 각각 730 m²g^-1와 70.8 Å이었다. 한편, 포스트-합성방법(post-synthesis method)을 이용하여 메조세공 내에 아미노실란(3-aminopropyltriethoxysilane, APTES)을 그래프팅(grafting) 하였다. 아미노실란으로 개질된 메조다공성 실리카(APTES-SBA-15)는 잘 배열된 세공구조(p6mm)를 가지고 짧은 로드의 입자모양을 잘 유지 하였다. APTES-SBA-15의 표면적과 세공 직경은 각각 350 m²g^-1와 60.7 Å으로 감소하였다. APTES가 개질된 메조 다공성 실리카에 희토류 금속이온(Eu³⁺, Tb³⁺) 용액을 처리하여 메조세공 내에 희토류 금속 착물이 도입된 메조다공성 실리카 물질을 합성하였다. (Eu/APTES-SBA-15, Tb/APTES- SBA-15) 이들 물질은 λ_ex=250 nm 광에 의해 특징적인 광발광 스펙트라를 나타내었다. (Tb/APTES-SBA-15를 위하여 ⁵D₄→⁷F₅ (543.5 nm), ⁵D₄→⁷F₄ (583.5 nm), ⁵D₄→⁷F₃ (620.2 nm) 전이; Eu/APTES-SBA-15를 위하여 ⁵D0→⁷F₀ (577.7 nm), ⁵D0→⁷F₁ (592.0 nm), ⁵D0→⁷F₂ (614.9 nm), ⁵D₀→⁷F₃ (650.3 nm) and ⁵D₀→⁷F₄ (698.5 nm) 전이)

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 추계학술대회
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• pp.543-545
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• 2017

본 논문에서는 고성능 루프내 필터를 위한 SAO 하드웨어 구조 설계에 대해 기술한다. SAO는 루프내 필터 내부 모듈이며, 블록 단위 영상 압축 및 양자화 등에서 발생하는 정보의 손실을 보상하는 기술이다. 하지만, HEVC의 SAO는 픽셀 단위 연산을 수행하기 때문에 높은 연산 시간을 요구한다. 따라서 본 논문에서 제안하는 SAO 하드웨어 구조는 고속연산을 위해 $4{\times}4$ 블록 연산과 2단 파이프라인 구조를 기반으로 한다. SAO 연산을 위한 정보생성 및 offset 연산구조는 병렬구조로 설계하여 연산시간을 최소화 하였다. 제안하는 하드웨어 구조는 Verilog HDL로 설계하였으며, TSMC 칩 공정 130nm 및 65nm 셀 라이브러리로 합성을 진행하였다. 130nm에서 최대 동작 주파수는 476MHz이고, 전체 게이트 수는 163k이다. 65nm에서 최대 동작 주파수는 312.5MHz이고, 전체 게이트 수는 193.6k이다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.543-543
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• 2013

Thin-film transistors (TFTs) based on oxide semiconductors have been regarded as promising alternatives for conventional amorphous and polycrystalline silicon TFTs. Oxide TFTs have several advantages, such as low temperature processing, transparency and high field-effect mobility. Lots of oxide semiconductors for example ZnO, SnO2, In2O3, InZnO, ZnSnO, and InGaZnO etc. have been researched. Particularly, zinc-tin oxide (ZTO) is suitable for channel layer of oxide TFTs having a high mobility that Sn in ZTO can improve the carrier transport by overlapping orbital. However, some issues related to the ZTO TFT electrical performance still remain to be resolved, such as obtaining good electrical contact between source/drain (S/D) electrodes and active channel layer. In this study, the bottom-gate type ZTO TFTs with staggered structure were prepared. Thin films of ZTO (40 nm thick) were deposited by DC magnetron sputtering and performed at room temperature in an Ar atmosphere with an oxygen partial pressure of 10%. After annealing the thin films of ZTO at $400^{\circ}C$ or an hour, Cu, Mo, ITO and Ti electrodes were used for the S/D electrodes. Cu, Mo, ITO and Ti (200 nm thick) were also deposited by DC magnetron sputtering at room temperature. The channel layer and S/D electrodes were defined using a lift-off process which resulted in a fixed width W of 100 ${\mu}m$ and channel length L varied from 10 to 50 ${\mu}m$. The TFT source/drain series resistance, the intrinsic mobility (${\mu}i$), and intrinsic threshold voltage (Vi) were extracted by transmission line method (TLM) using a series of TFTs with different channel lengths. And the performances of ZTO TFTs were measured by using HP 4145B semiconductor analyzer. The results showed that the Cu S/D electrodes had a high intrinsic field effect mobility and a low effective contact resistance compared to other electrodes such as Mo, ITO and Ti.

• 한국생산제조학회지
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• 제22권3_1spc호
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• pp.537-543
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• 2013

A water-$Al_2O_3$ nanofluid was manufactured, and its thermal conductivity was measured in this study. The measurement was performed at volumetric concentrations of 0.5%, 1%, 2%, and 3%, and the nanoparticle sizes were 20 nm and 70 nm. Experimental test equipment, using the transient hot wire method, was installed to measure the thermal conductivity of the nanofluid, and the measured results were confirmed by measuring pure water with a measurement error of 0.92% at $20^{\circ}C$. The thermal conductivity enhancement ranged from 4.8% to 13.6% for the 20 nm particle size, and from 3.1% to 8.8% for the 70 nm particle size at a concentration range of 0.5% to 3%. The enhancement increased with a decrease in particle size and an increase in concentration. With the elapse of time after manufacturing the nanofluid, the thermal conductivity enhancement decreased significantly from 5 to 9 h, and this trend was measured under all of the measurement conditions. After 24 h, the enhancement ranged from 1.2% to 3.5% for the 20 nm particles, and from 0.6% to 2.3% for the 70 nm particles. The enhancement trends with the elapse of time were almost identical with and without stirring the nanofluid. SDBS (Sodium Dodecyl Benzene Sulfonate) was added as a dispersing agent, and the decrease in the thermal conductivity enhancement was delayed.

• 한국환경과학회지
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• 제26권4호
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• pp.543-547
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• 2017

Normalized Difference Vegetation Index (NDVI) has played an important role in assessing green plant biomass through remote sensing on global scale since the early 1970s. The concept of NDVI is based on the fact that green plants show higher reflection in near-infrared region than in visible region of the electromagnetic spectrum. However, it is well known that the relocation of chloroplasts in plant leaf cells may dramatically change the optical properties of plant leaves. In this study I traced the changes in the reflectance and transmittance properties of Tobacco leaves at the wavelengths of 660 and 800 nm after a sudden increase in light intensity. The results showed that NDVI of leaves gradually decreased from 72.7% to 69.9% when exposed to a sudden increase in light intensity from 30 to $1,200{\mu}mol/m^2{\cdot}s$. This means that the error resulting from the physiological status of the plant should be accounted for a more precise understanding of ground truth corresponding to the data from the remotely acquired images.

• 한국재료학회지
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• 제16권9호
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• pp.543-549
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• 2006

Polyimides (PI) are treated with $He/O_2$ and $He/O_2/NF_3$ atmospheric pressure rf dielectric barrier discharge in order to investigate the roles of $NF_3$ that is one of the PI etching gases. Surface changes are analyzed by x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and contact angle measurement. The surface roughness of PI and the ratio of C=O, which is hydrophilic functional group, is more increased by $He/O_2/NF_3$ discharge than by $He/O_2$ discharge. The C=O species on the PI surface is increased up to 30 percent with rf power. The surface roughness of PI is increased from 0.4 to 11 nm with rf power. The water drop contact angles on PI, however, are reduced from $65^{\circ}\;to\;9^{\circ}$ by plasma treatment independently of $NF_3$.

• Korean Chemical Engineering Research
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• 제53권6호
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• pp.776-782
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• 2015

$TiO_2$ 나노입자의 광촉매 반응을 억제하기 위해 평균 직경 3~5 nm의 $TiO_2-SnO_2$ 나노입자가 titanium tetraisopropoxide(TTIP)와 tin chloride의 가수분해 반응에 의해 합성되었다. 생성된 $TiO_2-SnO_2$ 나노입자를 졸-겔법에 의해 3-glycidoxypropyl trimethoxysilane(GPTMS)과 반응시킴에 의해 유-무기 혼성 코팅 용액이 제조되었다. 그 후 코팅 용액을 기재인 polycarbonate(PC) 시트 위에 스핀 코팅시키고, $120^{\circ}C$에서 열경화 시켜 고굴절률 하드코팅 도막이 제조되었다. $TiO_2-SnO_2$ 나노입자로부터의 코팅 도막은 $TiO_2$ 나노입자로부터 얻어진 코팅 도막의 2H에 비해 증가된 3H의 연필경도를 보였다. 또한 $TiO_2-SnO_2$ 나노입자로부터의 코팅 도막의 굴절률은 Sn/Ti 몰 비가 0에서 0.5로 증가함에 따라 633 nm 파장에서 1.543으로부터 1.623으로 향상되었다.

• Bulletin of the Korean Chemical Society
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• 제34권9호
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• pp.2774-2780
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• 2013

Two new isostructural dinuclear complexes, $Ln_2(4-cpa)_6(bpy)_2$ (Ln = Eu (1); Tb (2), 4-cpa = 4-chlorophenylacetate, bpy = 2,2'-bipyridine), have been hydrothermally synthesized and characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis (TGA), powder X-ray diffraction and single-crystal X-ray diffraction. The lanthanide ions are bridged by two bidentate and two terdentate carboxylate groups to give centrosymmetric dimers with $Ln{\cdots}Ln$ separations of 3.967(2) and 3.956(3) ${\AA}$, respectively. Each metal atom is nine-coordinate and exhibits a distorted tricapped trigonal prismatic geometry. Three-dimensional fluorescence spectra show that both 1 and 2 emit bright red and green luminescence at room temperature, with long lifetimes of up to 0.369 ms (at 614 nm) and 0.432 ms (at 543 nm), respectively. Moreover, poor luminescence efficiency has been noted for complex 2. The 4-Hcpa ligand and complexes 1-2 have been screened for their phytogrowth-inhibitory activities against Brassica napus L. and Echinochloa crusgalli L., and the results are compared with the activity of quizalofop-P-ethyl.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVI)
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• pp.541-543
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• 2005

조협은 trosinase 저해 활성 실험 결과 1.9%(w/v) 이상의 농도에서 70%이상의 저해를 나타내고, UV 흡수능에서는 220-230nm 에서 최대 흡수 파장이 나타나고 250-550nm 에서 고르게 흡수되는 경향을 보인다. 조협은 자외선 차단효과와 활성산소종 형성 억제 및 멜라닌 생성을 저해함으로써 피부미백 효과에 기여한다. 따라서 조협을 이용한 liposome을 제조하여 미백화장품에의 응용 가능성을 높여 줄 수 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.542-543
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• 2012

Coherent diffraction imaging (CDI) method using hard x-ray at 5.46 keV was applied to study assembly of Ni and Ni oxide nano structures formed on a Si3N4 membrane. Density distribution of Ni nano-particles was obtained quantitatively with about 15 nm lateral resolution by reconstructing images from the speckle diffraction pattern. In addition, reconstructed images of nickel oxide particles indicated that Ni atoms diffuse out during the oxidation process leaving pores inside the nickel oxide crust. Furthermore, we recognize that really weak phase object, less than 5 nm thickness of Ni residues, can be reconstructed due to the reference particles. We achieved quantitative information of nanometer sized materials and demonstrate the effect of reference particles by using hard x-ray coherent diffractive imaging method.