• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.388-388
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• 2016

Chemical mist deposition (CMD) of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was investigated with cavitation frequency f, solvent, flow rate of nitrogen, substrate temperature $T_s$, and substrate dc bias $V_s$ as variables for efficient PEDOT:PSS/crystalline (c-)Si heterojunction solar cells (Fig. 1). The high-speed camera and differential mobility analysis characterizations revealed that average size and flux of PEDOT:PSS mist depend on f, solvent, and $V_s$. The size distribution of mist particles including EG/DI water cosolvent is also shown at three different $V_s$ of 0, 1.5, and 5 kV for a f of 3 MHz (Fig. 2). The size distribution of EG/DI water mist without PEDOT:PSS is also shown at the bottom. A peak maximum shifted from 300-350 to 20-30 nm with a narrow band width of ~150 nm for PEDOT:PSS solution, whose maximum number density increased significantly up to 8000/cc with increasing $V_s$. On the other hand, for EG/water cosolvent mist alone, the peak maximum was observed at a 72.3 nm with a number density of ~700/cc and a band width of ~160 nm and it decreased markedly with increasing $V_s$. These findings were not observed for PEDOT:PSS/EG/DI water mist. In addition, the Mie scattering image of PEDOT:PSS mist under white bias light was not observed at $V_s$ above 5 kV, because the average size of mist became smaller. These results imply that most of solvent is solvated in PEDOT:PSS molecule and/or solvent is vaporized. Thus, higher f and $V_s$ generate preferentially fine mist particle with a narrower band width. Film deposition occurred when $V_s$ was impressed on positive to a c-Si substrate at a Ts of $30-40^{\circ}C$, whereas no deposition of films occurred on negative, implying that negatively charged mist mainly provide the film deposition. The uniform deposition of PEDOT:PSS films occurred on textured c-Si(100) substrate by adjusting $T_s$ and $V_s$. The adhesion of CMD PEDOT:PSS to c-Si enhanced by $V_s$ conspicuously compared to that of spin-coated film. The CMD PEDOT:PSS/c-Si solar cell devices on textured c-Si(100) exhibited a ${\eta}$ of 11.0% with the better uniformity of the solar cell parameters. Furthermore, ${\eta}$ increased to 12.5% with a $J_{sc}$ of $35.6mA/cm^2$, a $V_{oc}$ of 0.53 V, and a FF of 0.67 with an antireflection (AR) coating layer of 20-nm-thick CMD molybdenum oxide $MoO_x$ (n= 2.1) using negatively charged mist of 0.1 wt% 12 Molybdo (VI) phosphoric acid n-Hydrate) $H_3(PMo_{12}O_40){\cdot}nH_2O$ in methanol. CMD. These findings suggest that the CMD with negatively charged mist has a great potential for the uniform deposition of organic and inorganic on textured c-Si substrate by adjusting $T_s$ and $V_s$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4081-4086
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• 2014

Cellulose acetate butyrate (CAB) is a biodegradable resin with excellent optical properties, but it is difficult to apply film process. In this study, an attempt was made to improve the processability of CAB using polyactic acid and the mechanical properties using an impact modifier. Polylacitc acid (PLA)/Cellulose acetate butyrate (CAB) blends with an impact modifier were prepared using a twin screw extruder. The temperature range was $140^{\circ}C$ to $200^{\circ}C$, and the screw speed was fixed to 200 rpm. To evaluate the miscibility of impact modified CAB/PLA, the glass transition behavior and morphology were observed by DSC and FE-SEM. The mechanical properties were investigated by dynamic mechanical analysis (DMA) and a Universal Testing Machine (UTM). In addition, the effect of an impact modifier in the polymer matrix was determined using a notched Izod impact strength tester. Finally, the PLA/CAB/impact modifier 75/25/10 ratio was found to be a compatible system. In the 10wt.% impact modifier, the sample had a 4 times higher izod impact strength than the non-toughening composition.

• Membrane Journal
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• v.22 no.4
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• pp.272-279
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• 2012

The neutral polymer, poly (vinyl alcohol) (PVA), was coated onto polyamide (PA) thin film composite reverse osmosis (RO) membranes. And then these membranes were investigated for the model foulants, bovine serum albumin (BSA), humic acid (HA), and sodium alginate (SA) whether there are aome improvement. As the operating pressure increased with 2, 4, 8 atm for BSA, HA and SA 100 ppm in feed solution, the fouling phenomena was worse for both none and PSSA coated membranes. The fouling occurred in the sequence of BSA > HA > SA due to the interactions between PVA snd functional groups of foulants, and on the other hand the fouling reduction was observed in the order of HA > BSA > SA. The observation of scanning electron microscopy photographs showed the same trend. As a result, there should be the improvement of fouling phenomena for the PVA coated RO membranes and the case of HA was shown distinct.

• KIPS Transactions on Software and Data Engineering
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• v.4 no.9
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• pp.357-370
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• 2015

Massive data occurred in a manufacturing place is able to fulfill very important roll to improve the manufacturing process. Domestic manufacturing business has been making an multilateral effort to react the change of manufacturing circumstance, but it undergoes many difficulties due to technical weakness. Coatings is a type of paint. It protect products by forming a film layer on the products and assigns various properties to those. The research of coatings is one of the fields studied actively in the polymer industry. The importance of the coatings in various industries is more increased. However, the industry still performs a mixing process in dependence on operator's experiences. In this paper, we propose a design for realtime monitoring system and data analysis verification TA to improve the manufacturing process using HW-SW integrated framework. Analysis results from the proposed framework are able to improve the coatings formulation process by collecting more quantitative reference data for work and providing it to work place. In particular, the framework may reduce the deterioration and loss cost which are caused by absence of a standard data as a accurate formulation criteria. It also may suggest a counterplan regarding errors which can be occurred in the future by deriving a standard calibration equation from the analysis using R and Design of Experiments about an error data generated in the mixing step.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.97-104
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• 2004

Double-layered polysulfone composite films, containing cerium activated yttrium silicate (CAYS) as a flour, were prepared from double casting of two polymeric solutions, and their morphology and physical strength were superior to those of single-layered composites. The prepared polymeric films consist of a dense bottom layer and a CAYS-holding top layer. The former is made of coagulating the polysulfone and methylene chloride binary solution and works as a supporter to improve the composite's physical strength, while the latter holding the inorganic fluor plays a role as an active site to detect the radioactive contamination. The prepared films revealed two distinguished, but tightly attached, double layers, their attachment being identified by morphology of the interface between two layers. As prepared by water immersion coagulation, the films have highly developed macropores, compared with a dense structure in the film prepared by evaporation. In the radionuclide detection test of the CAYS-impregnated composites, the films have reliable detection capacity at a radionuclide spotting test. The double-layered composites with the dense support layer show a better stability in holding the radionuclides spotted on the surface as well as an improvement in physical strength, compared with the single-layer composites having shortcomings such as being too porous or being brittle.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.38.2-38.2
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• 2011

폴리머 박막은 그 고유한 특성으로 인해 여러 산업적으로 널리 사용되고 있는 재료이다 예로 의약품이나 식품 포장지의 배리어, 전자부품의 절연체, 반도체 공정에서의 사용, 혹은 부식방지를 위해 사용 되어지기도 한다. 이 폴리머 박막을 증착 하기 위한 방법으로 이전부터 CVD (Chemical Vapor Deposition) 방법이 많이 사용되었고 지금까지도 가장 많이 사용되는 방법이다. CVD를 사용하여 $SiO_2$-like 필름의 증착은 전구체(precursor)로 Silane ($SiH_4$)을 사용하였으며, 플라즈마 발생 소스(source)로 열 혹은 전기장 등을 사용 하며 공정 시 압력 또한 대부분 저압 하에서 실시 하였다. 이와 같은 이전 CVD 방법의 문제는 사용되는 Silane 자체가 인체에 해로울 정도로 독성이 있으며 폭발성도 같이 가지고 있어 작업환경의 위험성이 높으며 열을 사용한 CVD의 경우 높은 공정 온도로 인해 증착 할 수 있는 대상이 제한 되어 지며 높은 열의 발생을 위해 많은 에너지의 소비가 필요하다. 저압 플라즈마를 사용한 CVD 는 공정상 높은 열의 발생이 일어나지 않아 기판 운용상 문제가 되지 않지만 저압 환경에서 해당 공정이 이루어기 때문에 인해 필수적으로 고가의 진공 챔버가 필수적이며 저압을 유지할 고가의 진공 펌프나 추가 장비들이 필요하게 된다, 또한 챔버 내에서 이루어지는 공정으로 인해 공정의 연속성이 떨어져 시잔비용 또한 많이 잡아 먹는다. 이러한 열 혹은 저압 플라즈마등을 사용한 공정의 단점을 해결하기 위해 여러 연구자들이 다양한 방법을 통해 연구를 하였다. 대기압 유전체 배리어 방전(AP-DBD: Atmospheric Pressure-Dielectric Barrier Discharge)을 사용한 폴리머 박막의 증착은 이전 전통적인 방법에 비해 낮은 장비 가격과 낮은 공정 온도 그리고 연속적인 공정 등의 장점이 있는 폴리머 박막 증착 방법 이다. 대기압 유전체 배리어 방전 공정 변수로 공급 전압 및 주파수 그리고 공급 전압의 영향, 전구체를 유전체 배리어 방전 전극으로 이동 시키기 위해 사용된 캐리어 가스의 종류 및 유량, 화학양론적 계수를 맞추기 위해 같이 포함되는 산소 가스의 유량, DBD 전극의 형태에 따른 증착 박막의 균일성 등 이 존재하며 이런 많은 변수 들에 대한 연구가 진행 되었지만 아직 이 대기압 DBD를 이용한 폴리머 박막의 증착에 대한 명확한 이해는 아직 완전 하다 할 수 없다. 본 연구에서는 이러한 대기압 DBD를 이용하여 폴리머 박막의 증착시 영향을 미치는 많은 공정 변수 등이 박막생성에 미치는 영향과 증착된 박막의 성질에 대한 연구를 진행 하였다.

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.88-99
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• 1999

The purpose of this study was to investigate the physical properties of experimental composite resins made with the spherical and crushed fillers. The 14 experimental composite resins containing 0, 5, 10, 15, 20 and 25%(w/w) in spherical filler group and 0, 10, 20, 30, 40, 50, 60 and 70%(w/w) in crushed filler group, incorporated in a Bis-GMA matrix (Aldrich Co., USA), were made with 1% ${\gamma}$-methoxy silane treated fillers. The polymer matrix was made by dissolving 0.7%(w/w) of benzoyl peroxide(Janssen Chemical Co. Japan) in methacrylate monomer, whereupon 0.7%(v/v) N,N-dimethyl-p-toluidine(Tokyo Kasei Co. Japan) was added to the monomer. The weight percentage of each specific particle size distribution could be determined from a knowledge of the specific gravity, the weight(w/w), and corresponding volume %(v/v) of the filler sample in resin monomer. In crushed silica group and spherical silica group, the diametral tensile strengths and compressive strengths were measured with Instron Testing Machine(No.4467), and analyzed in 14 experimental composite resins made by filler fractions. The shear bond strength of 14 experimental composite resins to bovine enamel was measured with universal testing machine(Instron No.4467). The fracture surfaces were sputter-coated with a gold film and investigated by SEM. The results were as follows; 1. The diametral tensile strength was tendency to increase in crushed silica group, but not in spherical silica group. The highest diametral tensile strength was found in 20% filler fractions of two groups. 2. The compressive strength was higher in 15%(w/w) and 20%(w/w) in spherical silica group than in crushed silica group, but not in spherical silica group. 3. The significant correlation was noticed in increase in shear bond strength in crushed silica group, but not in spherical silica group. 4. The significantly highest shear bond strength was noticed in 50% filler concentration in crushed silica group, and in 15% filler concentration in spherical silica group, it was not significant in relation. 5. In crushed silica group, cut surface of resin matrix and the interface between resin and filler is obvious. In spherical silica group, fractures that occurred through the filler particles were round in shape.

• Korean Chemical Engineering Research
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• v.43 no.1
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• pp.85-91
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• 2005

$SnO_2$ films were prepared at room temperature under a $(CH_3)_4Sn-H_2-O_2$ atmosphere in order to obtain transparent conductive polymer by using ECR-MOCVD (Electron Cyclotron resonance -Metal Organic Chemical Vapor Deposition) system. The electrical properties of the films were investigated as function of process parameters such as deposition time, microwave power, magnetic current power, magnet/showering/substrate distance and working pressure. An increase in microwave power and magnetic current power brought on $SnO_2$ film formation with low electric resistivity. On the other hand, the effects of process parameters described above on optical properties were insignificant in the range of our experimental scope. The transmittance and reflectance of the films prepared by the ECR-MOCVD exhibited their average values of 93-98% at wave length range of 380-780 nm and 0.1-0.5%, respectively. The grain size of the $SnO_2$ films that are also insensitive with the process parameters were in the range of 20-50 nm. On the basis of experimental data obtained in the present study, electrical resistivity of $7.5{\times}10^{-3}ohm{\cdot}cm$, transmittance of 93%, and reflectance of 0.2% can be taken as optimum values.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.348-351
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• 2006

Bipolar plate, which forms about 50% of the stack cost, is an important core part with polymer electrolyte membrane in PEMFC. Bipolar plates have been commonly fabricated from graphite meterial having high electrical conductivity and corrosion resistance. Lately, many researchers have concentrated their efforts on the development of metallic bipolar plate and stainless steel has been considered as a potential material for metallic bipolar plate because of its high strength, chemical stability, low gas permeability and applicability to mass production. However, it has been reported that its inadequate corrosion behavior under PEMFC environment lead to a deterioration of membrane by dissolved metal ions and an increase in contact resistance by the growth of passive film therefore, its corrosion resistance as well as contact resistance must be improved for bipolar plate application. In this work, several types of coating were applied to 316L and their electrical conductivity and corrosion resistance were evaluated In the simulated PEMFC environment. Application of coating gave rise to low interfacial contact resistances below $19m{\Omega}cm^2$ under the compress force of $150N/cm^2$. It also made the corrosion potential to shift in the posit ive direct ion by 0.3V or above and decreased the corrosion current from ca. $9{\mu}A/cm^2$ to ca. $0.5{\mu}A/cm^2$ in the mixed solution of $0.1N\;N_2SO_4$ and 2ppm HF A coat ing layer under potentiostatic control of 0.6V and $0.75V_{SCE}$ for 500 hours or longer showed some instabilities, however, no significant change in coat Ing layer were observed from Impedance data. In addition, the corrosion current maintained less than $1{\mu}A/cm^2$ for most of time for potentiostatic tests. It indicates that high electrical conductivity and corrosion resistance can be obtained by application of coatings in the present work.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.475-480
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• 2017

In this paper, the conductivity of the fine pattern is improved in the insulating substrate by laser-induced forward transfer (LIFT) process. The high laser beam energy generated in conventional laser induced deposition processes induces problems such as low deposition density and oxidation of micro-patterns. These problems were improved by using a polymer coating layer for improved deposition accuracy and conductivity. Chromium and copper were used to deposit micro-patterns on silicon wafers. A multi-pulse laser beam was irradiated on a metal thin film to form a seed layer on an insulating substrate(SiO2) and electroless plating was applied on the seed layer to form a micro-pattern and structure. Irradiating the laser beam with multiple scanning method revealed that the energy of the laser beam improved the deposition density and the surface quality of the deposition layer and that the electric conductivity can be used as the microelectrode pattern. Measuring the resistivity after depositing the microelectrode by using the laser direct drawing method and electroless plating indicated that the resistivity of the microelectrode pattern was $6.4{\Omega}$, the resistance after plating was $2.6{\Omega}$, and the surface texture of the microelectrode pattern was uniformly deposited. Because the surface texture was uniform and densely deposited, the electrical conductivity was improved about three fold.