Highly self-cleaning thin films of TiO2-SiO2 co-doped with Ag and F are prepared by the sol-gel method. The asprepared thin films consist of bottom SiO2 and top TiO2 layers which are modified by doping with F, Ag and F-Ag elements. XRD analysis confirms that the prepared thin film is a crystalline anatase phase. UV-vis spectra show that the light absorption of Ag-F-TiO2/SiO2 thin films is tuned in the visible region. The self-cleaning properties of the prepared films are evaluated by a water contact angle measurement under UV light irradiation. The photocatalytic performances of the thin films are studied using methylene blue dye under both UV and visible light irradiation. The Ag-F-TiO2/SiO2 thin films exhibit higher photocatalytic activity under both UV and visible light compared with other samples of pure TiO2, Ag-doped TiO2, and F-doped TiO2 films.
The passivation of AZ91D Mg alloys by plasma anodization requires deliberate choice of process parameters due to the presence of large amounts of structural defects. We study the dependence of pore formation, surface roughness and corrosion resistance on voltage by comparing the direct current (DC) mode and the pulse wave (pulse) mode in which anodization is performed. In the DC plasma anodization mode, the thickness of the electrolytic oxide film of the AZ91D alloy is uneven. In the pulse mode, the thickness is relatively uniform and the formed thin film has a three-layer structure. The pulse mode creates less roughness, uniform thickness and improved corrosion resistance. Thus, the change of power mode from DC to pulse at 150 V decreases the surface roughness (Ra) from 0.9 μm to 0.1 μm and increases the corrosion resistance in rating number (RN) from 5 to 9.5. Our study shows that an optimal oxide film can be obtained with a pulse voltage of 150 V, which produces an excellent coating on the AZ91D casting alloy.
Conductive and dielectric SiC are fabricated using electroless plating of Ni–Fe films on SiC chopped fibers to obtain lightweight and high-strength microwave absorbers. The electroless plating of Ni–Fe films is achieved using a two-step process of surface sensitizing and metal plating. The complex permeability and permittivity are measured for the composite specimens with the metalized SiC chopped fibers dispersed in a silicone rubber matrix. The original noncoated SiC fibers exhibit considerable dielectric losses. The complex permeability spectrum does not change significantly with the Ni–Fe coating. Moreover, dielectric constant is sensitively increased with Ni–Fe coating, owing to the increase of the space charge polarization. The improvements in absorption capability (lower reflection loss and small matching thickness) are evident with Ni–Fe coating on SiC fibers. For the composite SiC fibers coated with Ni–Fe thin films, a -35 dB reflection loss is predicted at 7.6 GHz with a matching thickness of 4 mm.
Trogoderma variabile B. is one species of well-known stored product insect. This study was conducted to test the perforation ability of larvae of T. variabile on different packaging films which has been widely used in food industry at different thickness. The tested packaging films are polypropylene (PP) 20μm, low density polyethylene (LDPE) 20μm, polyethylene terephthalate (PET) 12μm, PP 30μm and PP 40μm. This investigation was carried out for 7 days. In the same order as the films mentioned above, the perforation rate are 33.33%, 0%, 14.81%, 29.62%, 0%. From these results, the easiest film to perforate among PP, LDPE, PET is PP, and there are significant differences on thickness. Therefore, different type of materials and thickness would be considered to be used for food packaging.
식품의 생물학적 위해요소인 해충과 유해균 및 부패균을 제어하기 위해 실제 포장필름 생산 공정 설비를 이용하여 방충 및 항균 기능성을 갖는 식품용 다층 포장필름을 제조하였다. 우선, 효과적인 활성 물질의 스크리닝 과정을 통해 식품의 대표적 해충인 화랑곡나방 유충(Plodia interpunctella)에 대해 기피력을 나타내는 팔각회향 에센셜 오일과, 황색포도상구균(Staphylococcus aureus) 및 페니실리움(Penicillium roqueforti)에 대해 항균력을 갖는 티몰(thymol)을 필름내 혼입할 활성 물질로 선정하였다. 선정된 활성 물질을 혼입한 폴리우레탄계 코팅액을 polyethylene terephthalate (PET) 12 μm 필름 표면에 코팅하였으며, 방충용 필름은 polypropylene (PP) 30 μm을, 항균용 필름은 low-density polyethylene (LDPE) 30 μm을 적층하여 다층필름의 구조로 제조하였다. Large-scale 생산 공정 설비를 통해 제조된 필름을 활용하여 유충에 대한 기피 효과와 항균력을 측정하였으며, 대조군 필름은 유충에 대한 기피력 및 항균 효과를 보이지 않은 반면, 개발된 방충 및 항균 필름은 화랑곡나방 유충과 두 가지 균에 대해 각각 뛰어난 기피력과 항균 효과를 보였다. 따라서, 본 연구는 식품 포장소재의 대량생산에 활용 가능한 표면 코팅 기술을 개발하고 그 방충효과 및 항균 효과를 입증함으로써 식품 중 생물학적 위해요소의 저감화를 위한 식품 포장 신소재 개발에 기여할 것이다.
최근 우수한 유연성과 화학적 안정성 등을 가진 고분자 수지와 우수한 기계적 성질 등을 나타내는 무기 재료로 이루어진 나노 복합 시스템으로써 유-무기 하이브리드 코팅 필름에 관한 연구가 활발히 진행되고 있다. 아크릴레이트 단량체로써 사용된 o-phenylphenoxyethyl acrylate (OPPEA)는 1.576의 높은 굴절률을 나타내고, Bisphenol A ethoxylate diacrylate (BAEDA)는 굴절률은 낮지만 경화된 고분자의 경도를 향상시킨다. 또한, 무기 소재로써 사용된 지르코니아는 산화지르코늄으로써 우수한 내구성과 광학특성 등을 나타낸다. 본 연구에서는 광학 특성을 향상시키기 위한 목적으로 아크릴레이트 단량체 중 BAEDA의 함량을 조절하여 필름을 제조한 뒤 연필 경도계와 아베굴절계를 이용하여 광학 특성 변화를 확인하였고, UV-vis spectrophotometer을 이용해 투과도를 비교하여 최적의 조건을 확립하였다. 그리고 실란 커플링제인 γ-methacryloxypropyltrimethoxysilane (MPS)를 사용하여 지르코니아를 소수화 처리하여 아크릴레이트 단량체에 대한 분산성을 향상시키고, 개질 전후의 물에 대한 분산성 변화를 조사하여 물에 대한 친화력이 감소하였음을 확인하였고, FT-IR ATR spectrophotometer를 통해 MPS에 의해 도입된 1716 cm-1에서의 에스터 C=O 결합 peak의 존재를 통해 MPS에 의한 지르코니아 표면의 개질 반응이 진행되었음을 확인하였다. 또한, 지르코니아의 표면에 도입된 규소 원자의 존재는 X 선 형광법을 이용하여 확인하였다. 그리고 화학적으로 개질된 지르코니아를 아크릴레이트 단량체에 도입하여 광경화 필름을 제조하였을 때, 굴절률은 아크릴레이트 자체 필름보다 1.2% 향상되었음을 확인하였고, SEM/EDS mapping 분석을 통해 PET 필름에 코팅된 개질 후 지르코니아가 아크릴레이트 코팅층에 균일하게 분포되어 있음을 알 수 있었다.
Copper oxide thin films are deposited using an ultrasonic-assisted spray pyrolysis deposition (SPD) system. To investigate the effect of substrate temperature and incorporation of a chelating agent on the growth of copper oxide thin films, the structural and optical properites of the copper oxide thin films are analyzed by X-ray diffraction (XRD), field-emssion scanning electron microscopy (FE-SEM), and UV-Vis spectrophotometry. At a temperature of less than 350 ℃, threedimensional structures consisting of cube-shaped Cu2O are formed, while spherical small particles of the CuO phase are formed at a temperature higher than 400 ℃ due to a Volmer-Weber growth mode on the silicon substrate. As a chelating agent was added to the source solutions, two-dimensional Cu2O thin films are preferentially deposited at a temperature less than 300 ℃, and the CuO thin film is formed even at a temperature less than 350 ℃. Therefore the structure and crystalline phase of the copper oxide is shown to be controllable.
We fabricated a Li-S battery with post-treated carbon nanotube (CNT) films which offered better support for sulfur, and investigated the effect of the surface properties and pore structure of the post-treated CNT films on Li-S battery performance. Post-treatments, i.e., acid treatment, unzip process and cetyltrimethylammonium bromide (CTAB) treatment, effectively modified the surface properties and pore structure of the CNT film. The modified pore structure impacted the ability of the CNT films to accommodate the catholyte, resulting in an increase in initial discharge capacity.
Tungsten oxide(WO3) films with uniform surface morphology are fabricated using a spin-coating method for applications of electrochromic(EC) devices. To improve the EC performances of the WO3 films, we control the heating rate of the annealing process to 10, 5, and 1 oC/min. Compared to the other samples, the WO3 films fabricated at a heating rate of 5 oC/min shows superior EC performances for transmittance modulation(49.5 %), response speeds(8.3 s in a colored state and 11.2 s in a bleached state), and coloration efficiency(37.3 cm2/C). This performance improvement is mainly related to formation of a uniform surface morphology with increased particle size without any cracks by an optimized annealing heating rate, which improves the electrical conductivity and electrochemical activity of the WO3 films. Thus, the WO3 films with a uniform surface morphology prepared by the optimized annealing heating rate can be used as a potential candidate for performance improvement of the EC devices.
TiN and CrN thin films are among the most used coatings in machine and tool steels. TiN and CrN are deposited by arc ion plating(AIP) method. The AIP method inhibits the reaction by depositing a hard, protective coating on the material surface. In this study, the characteristics of multi-layer(TiN/CrN/TiN(TCT), CrN/TiN/CrN(CTC)) are investigated. For comparison, TiN with the same thickness as the multilayer is formed as a single layer and analyzed. Thin films formed as multilayers are well stacked. The characteristics of micro hardness and corrosion resistance are better than those of single layer TiN. The TiN/CrN peak is confirmed because both TCT and CTC are formed of the same component(TiN, CrN), and the phase is first grown in the (111) direction, which is the growth direction. However, the adhesion and abrasion resistance of the multilayer films are somewhat lower.
본 연구는 ‘제조업 생산직 여성들의 생존권 투쟁’을 주제로 1980년대 한국의 민중미술운동의 영향을 받으며 ‘노동자로서의 여성’이라는 측면을 여성의 시각에서 스스로 표현하고자 한 한국의 여성주의 미술운동의 시발점에 주목하였다. 같은 맥락에서 1990년대 이후 노동자로서의 여성의 노동활동을 다룬 영상작품들이 계속하여 한국여성영상작가에 의해 발표되고 있는데, 이는 1980년대 산업체의 여성 노동운동을 뿌리를 두고 전개되기 시작한 한국의 여성주의 문화운동의 한 특징이다. 이것은 제2차 세계대전 이후 독립 국가들이 겪었던 경제성장과 민주화의 정착이라는 근대화의 역사를 배경으로 한국 사회의 경제성장구조에서 자신의 ‘노동’의 가치를 인정받고자 한 여성들의 주체의식에서 비롯되며 서구권의 여성주의 문화운동과는 그 역사적 차이점을 갖는다.
Among the fuel cell electrolyte candidates in the intermediate temperature range, glass materials show stable physical properties and are also expected to have higher ion conductivity than crystalline materials. In particular, phosphate glass has a high mobility of protons since such a structure maintains a hydrogen bond network that leads to high proton conductivity. Recently, defects like volatilization of phosphorus and destruction of the bonding structure have remarkably improved with introduction of cations, such as Zr4+ and Nb5+, into phosphate. In particular, niobium has proton conductivity on the surface because of higher surface acidity. It can also retain phosphorus content during heat treatment and improve chemical stability by bonding with phosphorus. In this study, we fabricate niobium phosphate glass thin films through sol-gel processing, and we report the chemical stability and electrical properties. The existence of the hydroxyl group in the phosphate is confirmed and found to be preserved at the intermediate temperature region of 150-450 oC.
Edible biopolymer films were developed from the exopolysaccharides (EPS) extracted from Weissella confusa 113-2. The optimum composition for film formation was determined using the response surface analysis with the explanatory variables of the EPS (0.5-5.5%) and glycerol (0.5-5.5%) concentrations and the response variable of film elastic modulus (EM). The mass ratio of distilled water to solids was set constant (14:1). Tensile strength (TS), percentage elongation at break (%E), EM, water vapor permeability (WVP) of EPS films were evaluated. The glass transition temperatures of the films were also determined by a dynamic mechanical analysis. The optimum mass ratio of EPS to glycerol was 0.754:0.375. The WVP, TS, %E, and EM of the film under the optimal composition were 3.53±0.21 g·mm/kPa·h·m2, 7.03±0.49 MPa, 84.82±12.31%, and 62.03±6.93 MPa, respectively. The glass transition temperature varied from 54 to 83 °C. The EPS film has the potential to be applied to food products as an edible film with physical and barrier properties comparable to other biopolymer edible films.
A protein-lipid film formed on the surface of soymilk by heating can be applied in various areas such as edible package film, cosmetic sheet, and meat analog. In this study, a colloid formulation of isolated soy protein (ISP) and soybean oil (4:1) was used to make protein-lipid films and it compared with the product using soymilk (Glycine max L. Merrill) for making a meat analog of fibrous shape. The colloid with 2.3 cm depth in a pan at 85︒C produced 8 sheets of protein-lipid films. The films were collected from the pan as a bundle to make a fibrous shape. Color parameters and texture profile analysis (TPA) were measured depending on the order of the film formation. Color parameters (Hunter-values) of the films using ISP and oil notably decreased the lightness and increased the redness as the order of the films. And changes of color differences in the films using ISP and oil were larger than those in the films using soymilk. TPA Parameters of the film such as hardness, resilience, springiness, cohesiveness, and gumminess were increased as increasing the order of the films formation. In the films using ISP and oil, lipid concentration was the highest in the first formed film rather than other films. However, in the films using soymilk, lipid concentration was similar among the order of the films. Consequently, the films using ISP and oil were produced non-uniformity of color, texture, and lipid composition in the order of the film formation compared with the films using soymilk. Combination of the soy protein-lipid films as a bundle could be used as a meat analog which had non-uniformity and fibrous shape.
TaNx film is grown by plasma enhanced atomic layer deposition (PEALD) using t-butylimido tris(dimethylamido) tantalum as a metalorganic source with various reactive gas species, such as N2+H2 mixed gas, NH3, and H2. Although the pulse sequence and duration are the same, aspects of the film growth rate, microstructure, crystallinity, and electrical resistivity are quite different according to the reactive gas. Crystallized and relatively conductive film with a higher growth rate is acquired using NH3 as a reactive gas while amorphous and resistive film with a lower growth rate is achieved using N2+H2 mixed gas. To examine the relationship between the chemical properties and resistivity of the film, X-ray photoelectron spectroscopy (XPS) is conducted on the ALD-grown TaNx film with N2+H2 mixed gas, NH3, and H2. For a comparison, reactive sputter-grown TaNx film with N2 is also studied. The results reveal that ALD-grown TaNx films with NH3 and H2 include a metallic Ta-N bond, which results in the film’s higher conductivity. Meanwhile, ALD-grown TaNx film with a N2+H2 mixed gas or sputtergrown TaNx film with N2 gas mainly contains a semiconducting Ta3N5 bond. Such a different portion of Ta-N and Ta3N5 bond determins the resistivity of the film. Reaction mechanisms are considered by means of the chemistry of the Ta precursor and reactive gas species.
In order to increase the efficiency of the sputtering method widely used in thin film fabrication, a dc sputtering apparatus which supplies both high frequency and magnetic field from the outside was fabricated, and cobalt thin film was fabricated using this apparatus. The apparatus can independently control the applied voltage, the target-substrate distance, and the target current, which are important parameters in the sputtering method, so that a stable glow discharge is obtained even at a low gas pressure of 10−3 Torr. The fabrication conditions using the sputtering method were mainly performed in Ar+O2 mixed gas containing about 0.6% oxygen gas under various Ar gas pressures of 1 to 30 mTorr. The microstructure of Co thin films deposited using this apparatus was examined by electron diffraction pattern and X-ray techniques. The magnetic properties were investigated by measuring the magnetization curves. The microstructure and magnetic properties of Co thin films depend on the discharge gas pressure. The thin film fabricated at high gas pressure showed a columnar structure containing a large amount of the third phase in the boundary region and the thin film formed at low gas pressure showed little or no columnar structure. The coercivity in the plane was slightly larger than that in the latter case.
In order to explore the similarities and differences among the "Petty bourgeois" factors in the various periods of Chinese film, this paper traces the evolution of the "Petty bourgeois" factors in the context of the Mao era, the Deng era, and the globalization era, respectively. First of all, under the Guidance of "Literature and Art Serving the Workers, Peasants and Soldiers" in the Mao era, film became a tool for propagating the ideology of class struggle. Elements of petty bourgeoisie literature such as "Individualism, Critical Realism, Sentimentalism" were abandoned and obscured in the film. The urban petty bourgeoisie was the main cinema audiences at the time, but it was not the subject of film creation. Second, in the era of Deng, as the reform of the social commodity economy, the traumatic literature film with the characteristics of "Individualism and Sentimentalism" was popular with the public. "Petty bourgeois" elements of literature and art abandoned by the Mao era began to return to the stage of history. Especially in the late 1980s, the "Wang Shuo Literature" movie, which depicts a special youth class in modern Chinese society, opened the prelude to the "new" Petty bourgeois era. Finally, with the return of Hollywood films to the Chinese market in 1995, Chinese films entered the era of globalization. Hollywood films produced a large amount of "new" petty bourgeois with the aesthetic taste of "Western middle class." With the rise of "new" petty bourgeois, films which expressed romance, rebellion, sentimental, comedy have become part of China’s diversified film market. Students and urban youth with “new” petty bourgeois character became the subject of the “new” petty-bourgeois films. The main body of Chinese film creation has taken a step closer to the image of a multi-faceted public image.
Li-incorporated ZnO thin films were deposited by using ultrasonic-assisted spray pyrolysis deposition (SPD) system. To investigate the effect of Li-incorporation on the performance of ZnO thin films, the structural, electrical, and optical properites of the ZnO thin films were analyzed by means of X-ray diffraction (XRD), field-emssion scanning electron microscopy (FE-SEM), Hall effect measurement, and UV-Vis spectrophotometry with variation of the Li concentraion in the ZnO sources. Without incorporation of Li element, the ZnO surface showed large spiral domains. As the Li content increases, the size of spiral domains decreased gradually, and finally formed mixed small grain and one-dimensional nanorod-like structures on the surface. This morphological evolution was explained based on an anti-surfactant effect of Li atoms on the ZnO growth surface. In addition, the Li-incorporation changed the optical and electrical properties of the ZnO thin films by modifying the crystalline defect structures by doping effects.
Sb-doped SnO2 (ATO) transparent conducting films are fabricated using horizontal ultrasonic spray pyrolysis deposition (HUSPD) to form uniform and compact film structures with homogeneously supplied precursor solution. To optimize the molar concentration and transparent conducting performance of the ATO films using HUSPD, we use precursor solutions of 0.15, 0.20, 0.25, and 0.30 M. As the molar concentration increases, the resultant ATO films exhibit more compact surface structures because of the larger crystallite sizes and higher ATO crystallinity because of the greater thickness from the accelerated growth of ATO. Thus, the ATO films prepared at 0.25 M have the best transparent conducting performance (12.60±0.21 Ω/□ sheet resistance and 80.83% optical transmittance) and the highest figure-of-merit value (9.44±0.17 × 10-3 Ω-1). The improvement in transparent conducting performance is attributed to the enhanced carrier concentration by the improved ATO crystallinity and Hall mobility with the compact surface structure and preferred (211) orientation, ascribed to the accelerated growth of ATO at the optimized molar concentration. Therefore, ATO films fabricated using HUSPD are transparent conducting film candidates for optoelectronic devices.
In this study, we synthesize tungsten oxide thin films by electrodeposition and characterize their electrochromic properties. Depending on the deposition modes, compact and porous tungsten oxide films are fabricated on a transparent indium tin oxide (ITO) substrate. The morphology and crystal structure of the electrodeposited tungsten oxide thin films are investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). X-ray photoelectron spectroscopy is employed to verify the chemical composition and the oxidation state of the films. Compared to the compact tungsten oxides, the porous films show superior electrochemical activities with higher reversibility during electrochemical reactions. Furthermore, they exhibit very high color contrast (97.0%) and switching speed (3.1 and 3.2 s). The outstanding electrochromic performances of the porous tungsten oxide thin films are mainly attributed to the porous structure, which facilitates ion intercalation/deintercalation during electrochemical reactions.