• 대한화학회지
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• 제17권4호
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• pp.247-255
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• 1973

$Li^{+},\;Na^{+},\;K^{+}, Ca^{2+},\;Ni^{2+},\;Al^{3+}$, 과 $F^{3+}$의 陽이온을 포화시킨 Wyoning montmorillonite에 acetone, methyl-ethyl ketone. diethyl ketone을 加熱用 i.r. gas cell 內에서 各各 다른 壓力아래 吸着시켜 $4000{\sim}1200cm^{-1}$에서spectra를 얻었다.두가지 형태의 C=O결합변화가$1713cm^{-1}$과 $1690cm^{-1}$ 나타났으며 이들은 陽이온의 水酸基 및 吸着水와 그리고 表面水酸基와 水素結合을 일으키는 결과로 나타났다. OH 吸收 spectra의 强度는 陽이온의 水酸基의 resonance 理論을 뒷받침해 주었다. coordinate bond를 일으키는 경향은 計算한 C=O기의 酸素의 formal charge의 크기와 잘 맞았다.

• 한국재료학회지
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• 제24권1호
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• pp.60-65
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• 2014

Fe-based amorphous coatings were fabricated on a soda-lime glass substrate by the vacuum kinetic spray method. The effect of the gas flow rate, which determines particle velocity, on the deposition behavior of the particle and microstructure of the resultant films was investigated. The as-fabricated microstructure of the film was studied by field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HR-TEM). Although the activation energy for transformation from the amorphous phase to crystalline phase was lowered by severe plastic deformation and particle fracturing under a high strain rate, the crystalline phases could not be found in the coating layer. Incompletely fractured and small fragments 100~300 nm in size, which are smaller than initial feedstock material, were found on the coating surface and inside of the coating. Also, some pores and voids occurred between particle-particle interfaces. In the case of brittle Fe-based amorphous alloy, particles fail in fragmentation fracture mode through initiation and propagation of the numerous small cracks rather than shear fracture mode under compressive stress. It could be deduced that amorphous alloy underwent particle fracturing in a vacuum kinetic spray process. Also, it is considered that surface energy caused by the formation of new surfaces and friction energy contributed to the bonding of fragments.

• 전기화학회지
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• 제2권4호
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• pp.202-208
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• 1999

[ $50/50 vol\%$ ] LSM-YSZ의 양극은 콜로이드 증착법에 의해 YSZ 전해질상에 증착하였다. 양극 특성은 주사전자현미경과 임피던스 분석기에 의해 고찰하였다. LSM-YSZ양극의 제조 조건에 따른 영향을 관찰하였으며, 그 영향에 대한 개선책이 고체산화물 연료전지의 성능향상을 위해 제시되었다. 임피던스에 대한 온도, YSZ전해질로의 양극 접착에 대한 표면 오염, 사용하는 Pt 페이스트, 미세구조에 대한 곡표면에 가해진 연무질 분사기술과 셀과 셀의 변동성에 대한 영향들은 각각 $900^{\circ}C$ 측정, YSZ표면 연마, 일단의 Pt페이스트 사용, 평편한 YSZ판의 사용과 일관된 절차와 기술의 사용에 의해 해결되었다. 이때 재현성 있는 임피던스 스펙트럼들이 향상된 셀을 사용함으로써 얻어졌고, $900^{\circ}C$에서 (공기)LSM-YSZ/YSZ/LSM-YSZ(공기) 셀에 대해 측정된 전형적인 임피던스 스펙트럼들은 2개의 불완전한 호로 구성되었다. 또한 LSM-YSZ 양극의 임피던스 특성은 촉매층, 양극 조성, 인가 전류 등과 같은 실험 조건들에 의해서도 영향을 받았다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
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• pp.170-170
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• 2000

Synthetic polymers such as polyimide, polycarbonate, and poly(methyl methacrylate) are long chain molecules which consist of carbon, hydrogen, and heteroatom linked together chemically. Recently, polymer surface can be modified by using a high energy ion beam process. High energy ions are introduced into polymer structure with high velocity and provide a high degree of chemical bonding between molecular chains. In high energy beam process the modified polymers have the highly crosslinked three-dimensionally connected rigid network structure and they showed significant improvements in electrical conductivity, in hardness and in resistance to wear and chemicals. Polyimide films (Kapton, types HN) with thickness of 50~100${\mu}{\textrm}{m}$ were used for investigations. They were treated with two different surface modification techniques: Plasma Source Ion Implantation (PSII) and conventional Ion Implantation. Polyimide films were implanted with different ion species such as Ar+, N+, C+, He+, and O+ with dose from 1 x 1015 to 1 x 1017 ions/cm2. Ion energy was varied from 10keV to 60keV for PSII experiment. Polyimide samples were also implanted with 1 MeV hydrogen, oxygen, nitrogen ions with a dose of 1x1015ions/cm2. This work provides the possibility for inducing conductivity in polyimide films by ion beam bombardment in the keloelectronvolt to megaelectronvolt energy range. The electrical properties of implanted polyimide were determined by four-point probe measurement. Depending on ion energy, doses, and ion type, the surface resistivity of the film is reduced by several orders of magnitude. Ion bombarded layers were characterized by Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS), XPS, and SEM.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.174-174
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• 2010

Gallium Nitride(GaN) attracts great attention due to their wide band gap energy (3.4eV), high thermal stability to the solid state lighting devices like LED, Laser diode, UV photo detector, spintronic devices, solar cells, sensors etc. Recently, researchers are interested in synthesis of polycrystalline and amorphous GaN which has also attracted towards optoelectronic device applications significantly. One of the alternatives to deposit GaN at low temperature is to use Single Source Molecular Percursor (SSP) which provides preformed Ga-N bonding. Moreover, our group succeeds in hybridization of SSP synthesized GaN with Single wall carbon nanotube which could be applicable in field emitting devices, hybrid LEDs and sensors. In this work, the GaN thin films were deposited on c-axis oriented sapphire substrate by MBE (Molecular Beam Epitaxy) using novel single source precursor of dimethyl gallium azido-tert-butylamine($Me_2Ga(N_3)NH_2C(CH_3)_3$) with additional source of ammonia. The surface morphology, structural and optical properties of GaN thin films were analyzed for the deposition in the temperature range of $600^{\circ}C$ to $750^{\circ}C$. Electrical properties of deposited thin films were carried out by four point probe technique and home made Hall effect measurement. The effect of ammonia on the crystallinity, microstructure and optical properties of as-deposited thin films are discussed briefly. The crystalline quality of GaN thin film was improved with substrate temperature as indicated by XRD rocking curve measurement. Photoluminescence measurement shows broad emission around 350nm-650nm which could be related to impurities or defects.

• 대한금속재료학회지
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• 제50권8호
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• pp.569-573
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• 2012

In order to understand the difference in SiC deposition between the $CH_3SiCl_3-H_2$ and $C_3H_8-SiCl_4-H_2$ systems, we calculate the phase stability among ${\beta}$-SiC, graphite and silicon. We constructed the phase-diagram of ${\beta}$-SiC over graphite and silicon via computational thermodynamic calculation considering pressure (P), temperature (T) and gas composition (C) as variables. Both P-T-C diagrams showed a very steep phase boundary between the SiC+C and SiC region perpendicular to the H/Si axis, and also showed an SiC+Si region with a H/Si value of up to 6700 in the $C_3H_8-SiCl_4-H_2$, and 5000 in the $CH_3SiCl_3-H_2$ system. This difference in phase boundaries is explained by the ratio of Cl to Si, which is 4 for the $C_3H_8-SiCl_4-H_2$ system and 3 for the $C_3H_8-SiCl_4-H_2$ system. Because the C/Si ratio is fixed at 1 in the $CH_3SiCl_3-H_2$ system while it can be variable in the $C_3H_8-SiCl_4-H_2$ system, the functionally graded material is applicable for better mechanical bonding during SiC coating on graphite substrate in the $C_3H_8-SiCl_4-H_2$ system.

• 한국인터넷방송통신학회논문지
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• 제19권4호
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• pp.35-39
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• 2019

3차원 구조에서 EMI 스프레이 코팅막의 차폐효과(SE)를 측정하였다. 차폐효과의 측정은 동축형 표준 측정기를 이용하는 ASTM D4935 방법으로 수행하였다. ASTM D4935의 동축형 표준 측정기를 이용하여 차폐효과를 측정하기 위하여 원통 슬랩(Slab)의 표준 시료를 가공하여 넣게 된다. 이 때 표준 시료에 낸드 플래시 메모리를 모델링한 3차원 구조를 접합하여 스프레이 코팅을 하였다. 스프레이 코팅의 경우 3차원 구조의 수평면뿐만 아니라 수직면에도 균일하게 코팅이 되었다. 측정결과, 3차원 구조에서도 3차원 구조가 없는 샘플과 비슷하게 최대 59 dB의 차폐효과가 측정되었다. 이러한 결과로 3차원 구조에서도 스프레이 코팅을 균일하게 할 수 있음을 확인하였다.

• 마이크로전자및패키징학회지
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• 제29권1호
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• pp.71-75
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• 2022

Graphene oxide를 ZnCl₂:NaCl 전해질과 함께 교반한 후 순환 전압전류법에 의해 전기화학적으로 제막하여 유기태양전지용 전자수송층 제막과정을 단순화하고 이를 갖는 유기태양전지를 제작하였다. 소자의 구조는 FTO/ZnO:graphene 전자수송층/P3HT:PCBM 광활성층/PEDOT:PSS 정공수송층/Ag이다. ETL의 형태 및 화학적 특성은 주사전자현미경(scanning electron microscopy, SEM), X선 광전자 분광법(X-ray photoelectron spectroscopy, XPS), 라만 분광법으로 확인하였다. XPS 측정결과 ZnO 금속산화물 및 탄소결합이 동시에 확인되었고, 라만 분광법에서 ZnO와 graphene 피크를 확인하였다. 제작한 태양전지의 전기적 특성을 솔라시뮬레이터로 측정하였고 0.05 V/s의 속도로 2회 제막한 ETL 소자에서 1.94%의 가장 높은 광전변환효율을 나타내었다.

• 한국건축시공학회지
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• 제23권1호
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• pp.1-9
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• 2023

본 연구에서는 보편적으로 건물의 옥상 등에 사용되는 폴리 우레탄 방수재의 바탕구조물의 함수정도와 시공환경조건에 따른 하자원인을 분석하기 위한 것으로 바탕판의 함수조건에 따른 부착강도, 표면상태를 육안관찰하였고, 온도, 습도의 양생조건에 따라서 방수재 도막의 기계적 성능을 평가하였다. 실험결과 바탕판의 함수상태가 10%이상일 때 도막의 부착이 이뤄지지 않음을 확인하였고, 온습도 조건이 20℃, 80% RH일때는 기초물성이 모두 확보되었으나, 40℃, 60% RH일 때 표면에 기포가 관찰되었으며, 40℃, 80% RH일 때 건조도막 기초물성이 KS F 3211 성능기준이하로, 우레탄 방수재 도포에 있어 시공환경조건의 하자원인 중 바탕판의 함수조건 및 양생 시 절대습도가 중요한 요인임을 확인하였다.

• 한국염색가공학회지
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• 제35권4호
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• pp.214-220
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• 2023

Poly(vinyl alcohol) (PVA) is a common hydrophilic polymer that is synthesized through the saponification reaction of poly(vinyl ester)-based polymers, mostly using poly(vinyl acetate) (PVAc) as a precursor. The heterogeneous saponification reaction of poly(vinyl ester)-based films leads to PVA films with new surface properties. Cellulose acetate (CA), in which the hydroxyl group of cellulose is replaced by an acetyl group, is a typical cellulose derivative capable of overcoming the low processability of cellulose due to strong hydrogen bonding. In this study, P(VAc/VPi)/CA blended films were prepared by the solvent casting, and then PVA/Cellulose blended films with improved surface properties were prepared by heterogeneous saponification. The structural changes caused by heterogeneous saponification were confirmed by FT-IR analysis, where both saponification and deacetylation reactions occurred in the saponification solution. In addition, the surface property changes were analyzed by FE-SEM and contact angle analyses, and the transmittance changes of the modified films were also assessed.