• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.429-429
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• 2016

Organolead halide perovskite have attracted much attention over the past three years as the third generation photovoltaic due to simple fabrication process via solution process and their great photovoltaic properties. Many structures such as mesoporous scaffold, planar heterojunction or 1-D TiO2 or ZnO nanorod array structures have been studied to enhance performances. And the photovoltaic performances and carrier transport properties were studied depending on the cell structures and shape of perovskite film. For example, the perovskite cell based on TiO2/ZnO nanorod electron transport materials showed higher electron mobility than the mesoporous structured semiconductor layer due to 1-D direct pathway for electron transport. However, the reason for enhanced performance was not fully understood whether either the shape of perovskite or the structure of TiO2/ZnO nanorod scaffold play a dominant role. In this regard, for a clear understanding of the shape/structure of perovskite layer, we applied anodized aluminum oxide material which is good candidate as the inactive scaffold that does not influence the charge transport. We fabricated vertical one dimensional (1-D) nanostructured methylammonium lead mixed halide perovskite (CH3NH3PbI3-xClx) solar cell by infiltrating perovskite in the pore of anodized aluminum oxide (AAO). AAO template, one of the common nanostructured materials with one dimensional pore and controllable pore diameters, was successfully fabricated by anodizing and widening of the thermally evaporated Al film on the compact TiO2 layer. Using AAO as a scaffold for perovskite, we obtained 1-D shaped perovskite absorber, and over 15% photo conversion efficiency was obtained. I-V measurement, photoluminescence, impedance, and time-limited current collection were performed to determine vertically arrayed 1-D perovskite solar cells shaped in comparison with planar heterojunction and mesoporous alumina structured solar cells. Our findings lead to reveal the influence of the shape of perovskite layer on photoelectrical properties.

• 전기화학회지
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• 제6권2호
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• pp.145-152
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• 2003

전해 캐패시터와 supercapacitor의 특성을 함께 가지는 하이브리드 캐패시터의 용량은 표면이 산화물로 피복된 양극에 의해서 좌우된다 본 연구에서는 고전압 하이브리드 슈퍼캐패시터의 제조를 위해 양극의 용량 최적화를 수행하였다. $40{\mu}m$의 입자경을 갖는 알루미늄 분말과 NaCl분말을 4:1의 무게비로 혼합하여 디스크 형태의 전극을 만들고 열처리를 하였다. 열처리 후 $50^{\circ}C$의 증류수에서 NaCl을 용해시켜 열처리 온도에 따른 용량과 저항을 비교하였다. 최적의 열처리 과정을 거친 후 electropolishing 및 화학처리, 1차 및 2차 에칭을 단계별로 행하였고 각각의 단계에서 최적의 조건을 조사하였다 각각의 단계에서의 용량과 저항은 ac impedance analyzer를 사용하여 측정하였으며 전극의 표면은 SEM을 이용하여 관찰하였다. 2차 에칭 후 내전압이 300V급인 전극으로 만들기 위하여 365V로 양극산화 시켰으며, 산화된 알루미늄 디스크 전극을 사용하여 단위 셀을 제조하여 주파수에 따른 용량과 저항 특성을 기존의 300V급 알루미늄 전해 캐패시터와 비교하였다.

• Corrosion Science and Technology
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• 제6권6호
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• pp.316-321
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• 2007

The effect of annealing on the pitting corrosion resistance of anodized Al-Mg alloy (AA5052) processed by equal-channel angular pressing (ECAP) was investigated by electrochemical techniques in a solution containing 0.2 mol/L of $AlCl_3$ and also by surface analysis. The Al-Mg alloy was annealed at a fixed temperature between 473 and 573 K for 120 min in air after ECAP. Anodizing was conducted for 40 min at $100-400A/m^2$ at 293 K in a solution containing 1.53 mol/L of $H_2SO_4$ and 0.0185 mol/L of $Al_2(SO_4)_3$. The internal stress generated in anodic oxide films during anodization was measured with a strain gauge to clarify the effect of ECAP on the pitting corrosion resistance of anodized Al-Mg alloy. The time required to initiate the pitting corrosion of anodized Al-Mg alloy was shorter in samples subjected to ECAP, indicating that ECAP decreased the pitting corrosion resistance. However, the pitting corrosion resistance was greatly improved by annealing after ECAP. The time required to initiate pitting corrosion increased with increasing annealing temperature. The strain gauge attached to Al-Mg alloy revealed that the internal stress present in the anodic oxide films was compressive stress, and that the stress was larger with ECAP than without. The compressive internal stress gradually decreased with increasing annealing temperature. Scanning electron microscopy showed that cracks occurred in the anodic oxide film on Al-Mg alloy during initial corrosion and that the cracks were larger with ECAP than without. The ECAP process of severe plastic deformation produces large internal stresses in the Al-Mg alloy; the stresses remain in the anodic oxide films, increasingthe likelihood of cracks. It is assumed that the pitting corrosion is promoted by these cracks as a result of the higher internal stress resulting from ECAP. The improvement in the pitting corrosion resistance of anodized AlMg alloy as a result of annealing appears to be attributable to a decrease in the internal stresses in anodic oxide films

• 전기화학회지
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• 제12권1호
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• pp.47-53
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• 2009

본 연구에서는 불순물이 포함된 Al 기판으로부터 두 단계의 양극산화 (anodization) 법에 의해 균일한 나노기공을 갖는 AAO(Anodic Aluminum Oxide)을 제조하였다. 생성된 AAO템플릿 위에 Deposition-Precipitation(DP)방법을 사용하여 수직으로 형성된 $TiO_2$ 나노섬유에 Au를 첨가시켜 2 wt.% $Au/TiO_2$ 나노섬유룰 제조하였다. 두 단계의 양극산화를 통해 규칙적으로 배열된 AAO 기공 형상과 기판 위에 수직으로 배향된 $TiO_2$ 나노섬유의 형상을 SEM을 통해 확인하였다. 또한 $Au/TiO_2$ 나노섬유의 특성은 XRD와 Raman 분석을 통하여 $TiO_2$의 아나타제(anatase)와 루타일(rutile) 결정구조와 $TiO_2$ 나노섬유에 담지된 Au의 존재를 확인하였다. 또한 일산화탄소(CO) 산화반응을 통해 AAO(Anodic Aluminum Oxide)기판 위에 형성된 $TiO_2$와 2 wt% $Au/TiO_2$ 나노섬유의 광촉매적 활성을 비교하였다.

• 한국재료학회지
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• 제23권4호
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• pp.240-245
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• 2013

Electrochemical surface treatment is commonly used to form a thin, rough, and porous oxidation layer on the surface of titanium. The purpose of this study was to investigate the formation of nanotubular titanium oxide arrays during short anodization processing. The specimen used in this study was 99.9% pure cp-Ti (ASTM Grade II) in the form of a disc with diameter of 15 mm and a thickness of 1 mm. A DC power supplier was used with the anodizing apparatus, and the titanium specimen and the platinum plate ($3mm{\times}4mm{\times}0.1mm$) were connected to an anode and cathode, respectively. The progressive formation of $TiO_2$ nanotubes was observed with FE-SEM (Field Emission Scanning Electron Microscopy). Highly ordered $TiO_2$ nanotubes were formed at a potential of 20 V in a solution of 1M $H_3PO_4$ + 1.5 wt.% HF for 10 minutes, corresponding with steady state processing. The diameters and the closed ends of $TiO_2$ nanotubes measured at a value of 50 cumulative percent were 100 nm and 120 nm, respectively. The $TiO_2$ nanotubes had lengths of 500 nm. As the anodization processing reached 10 minutes, the frequency distribution for the diameters and the closed ends of the $TiO_2$ nanotubes was gradually reduced. Short anodization processing for $TiO_2$ nanotubes of within 10 minutes was established.

• 한국재료학회지
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• 제22권8호
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• pp.439-444
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• 2012

To compare the photocatalytic performances of titania for purification of waste water according to applied voltages and doping, $TiO_2$ films were prepared in a 1.0 M $H_2SO_4$ solution containing $NH_4F$ at different anodic voltages. Chemical bonding states of F-N-codoped $TiO_2$ were analyzed using surface X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the co-doped $TiO_2$ films was analyzed by the degradation of aniline blue solution. Nanotubes were formed with thicknesses of 200-300 nm for the films anodized at 30 V, but porous morphology was generated with pores of 1-2 ${\mu}m$ for the $TiO_2$ anodized at 180 V. The phenomenon of spark discharge was initiated at about 98 V due to the breakdown of the oxide films in both solutions. XPS analysis revealed the spectra of F1s at 684.3 eV and N1s at 399.8 eV for the $TiO_2$ anodized in the $H_2SO_4-NH_4F$ solution at 180 V, suggesting the incorporation of F and N species during anodization. Dye removal rates for the pure $TiO_2$ anodized at 30 V and 180 V were found to be 14.0% and 38.9%, respectively, in the photocatalytic degradation test of the aniline blue solution for 200 min irradiation; the rates for the F-N-codoped $TiO_2$ anodized at 30 V and 180 V were found to be 21.2% and 65.6%, respectively. From the results of diffuse reflectance absorption spectroscopy (DRS), it was found that the absorption edge of the F-N-codoped $TiO_2$ films shifted toward the visible light region up to 412 nm, indicating that the photocatalytic activity of $TiO_2$ is improved by appropriate doping of F and N by the addition of $NH_4F$.

• 한국축산시설환경학회지
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• 제13권2호
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• pp.113-120
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• 2007

본 시험은 근적외선분광법을 이용한 돈분뇨 액비의 질소, 인산, 칼리, 수분 및 유기물의 분석 가능성을 구명하고, 이를 활용한 분석기의 개발을 목적으로 수행하였으며, 그 결과는 다음과 같다. 1. 돈분뇨 액비시료는 $400{\sim}2,500nm$ 대역의 근적외선을 시료에 투과하여 측정하였으며, 동일시료에 대한 습식분석 결과, N, $P_2O_5,\;K_2O$, 수분 및 유기물 함량은 각각 1,555mg/l, 302mg/l, 240mg/l, 98.8%, 0.53%로 조사되었다. 2. 근적외선 분광광도법을 이용한 분석에서 N, $P_2O_5,\;K_2O$, 수분 및 유기물에 대한 RSQ ($r^2$, R, Coefficient of determination)는 각각 0.9190, 0.9749, 0.5046, 0.9883 및 0.9777이었고 SEC(Standard Error of Calibration)는 2.1649, 0.5019, 1.9252, 0.1180 및 0.0789였다. 3. 액비에 대한 이화학적 습식분석과 NIR 흡수스펙트럼 측정결과를 비교 분석하여 돈 분뇨 액비에 포함된 질소, 인산, 칼리, 수분 및 유기물 함량을 실시간으로 분석하고 액비 성분량을 자동 계산할 수 있는 알고리즘을 도입한 액비분석 프로그램을 작성하였다. 4. 액비 성분분석 시작기는 근적외선(NIR : Near InfraRed)을 받아들여 실시간으로 액비성분의 흡수율을 측정하는 광검출장치(NIR Spectrometer), 근적외선 Light Source로부터 나오는 빛을 반사시키는 반사경, 액비성분 분석용 시료를 넣어 측정하는 Cell Mount, $400{\sim}2,500nm$ 대역의 가시광선-근적외선을 방출하는 Tungsten halogen lamp, NIR Spectrometer와 Tungsten halogen lamp로 전압을 입력시켜 주는 Power Supply Module 및 전체를 Black Anodizing한 외형으로 구성되었다. 5. 실험결과, 칼리를 제외한 액비내 모든 성분이 광을 흡수하는 강도는 성분의 농도에 비례하였으며 원시 스펙트럼의 중첩 제거 및 빛의 산란보정을 통해 액비의 질소, 인산성분, 수분 및 유기물 함량을 측정하는데 효과적으로 이용할 수 있을 것으로 사료되며, 분광분석법을 이용한 액비성분 분석기 개발이 완료되면 현장에서 신속하고 정확한 분석이 가능할 것으로 판단된다.

• Applied Science and Convergence Technology
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• 제27권1호
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• pp.9-13
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• 2018

Samples of anodic oxide film used in semiconductor and display manufacturing processes were prepared at different electrolyte temperatures to investigate the corrosion resistance. The anodic oxide film was grown on aluminum alloy 6061 by using a sulfuric acid ($H_2SO_4$) electrolyte of 1.5 M at $0^{\circ}C$, $5^{\circ}C$, $10^{\circ}C$, $15^{\circ}C$, and $20^{\circ}C$. The insulating properties of the samples were evaluated by measuring the breakdown voltage, which gradually increased from 0.43 kV ($0^{\circ}C$) to 0.52 kV ($5^{\circ}C$), 1.02 kV ($10^{\circ}C$), and 1.46 kV ($15^{\circ}C$) as the electrolyte temperature was increased from $0^{\circ}C$ to $15^{\circ}C$, but then decreased to 1.24 kV ($20^{\circ}C$). To evaluate the erosion of the film by fluorine plasma, the plasma erosion and the contamination particles were measured. The plasma erosion was evaluated by measuring the breakdown voltage after exposing the film to $CF_4/O_2/Ar$ and $NF_3/O_2/Ar$ plasmas. With exposure to $CF_4/O_2/Ar$ plasma, the breakdown voltage of the film slightly decreased at $0^{\circ}C$, by 0.41 kV; however, the breakdown voltage significantly decreased at $20^{\circ}C$, by 0.83 kV. With exposure to $NF_3/O_2/Ar$ plasma, the breakdown voltage of the film slightly decreased at $0^{\circ}C$, by 0.38 kV; however, the breakdown voltage significantly decreased at $20^{\circ}C$, by 0. 77 kV. In addition, for the entire temperature range, the breakdown voltage decreased more when sample was exposed to $NF_3/O_2/Ar$ plasma than to $CF_4/O_2/Ar$ plasma. The decrease of the breakdown voltage was lower in the anodic oxide film samples that were grown slowly at lower temperatures. The rate of breakdown voltage decrease after exposure to fluorine plasma was highest at $20^{\circ}C$, indicating that the anodic oxide film was most vulnerable to erosion by fluorine plasma at that temperature. Contamination particles generated by exposure to the $CF_4/O_2/Ar$ and $NF_3/O_2/Ar$ plasmas were measured on a real-time basis. The number of contamination particles generated after the exposure to the respective plasmas was lower at $5^{\circ}C$ and higher at $0^{\circ}C$. In particular, for the entire temperature range, about five times more contamination particles were generated with exposure to $NF_3/O_2/Ar$ plasma than for exposure to $CF_4/O_2/Ar$ plasma. Observation of the surface of the anodic oxide film showed that the pore size and density of the non-treated film sample increased with the increase of the temperature. The change of the surface after exposure to fluorine plasma was greatest at $0^{\circ}C$. The generation of contamination particles by fluorine plasma exposure for the anodic oxide film prepared in the present study was different from that of previous aluminum anodic oxide films.

• 대한치과보철학회지
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• 제47권1호
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• pp.39-45
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• 2009

연구목적: 최근 치과용 임플란트의 임상 경향이 전체 치료기간을 줄일 수 있는 방법에 관심이 집중됨에 따라 불활성의 티타늄 임플란트 표면에 활성을 부여하기 위한 다양한 표면처리 방법이 검토되고 있다. 본 연구에서는 높은 강도가 요구되는 부위의 임플란트 재료로서 사용되고 있지만 표면 특성이 순 티타늄에 비해 떨어지는 Ti-6Al-4V 합금의 골전도성을 개선할 목적으로 시행되었다. 연구 재료 및 방법: $20{\times}10{\times}2\;mm$의 Ti-6Al-4V 합금판을 준비한 다음 $TiO_2$ 나노튜브를 형성하기 위해 DC 정전원 장치의 양극과 음극에 각각 시편과 백금판을 결선하고 0.5 M $Na_2SO_4$와 1.0 wt% NaF를 함유하는 전해액을 사용하여 전압 20 V와 전류밀도 $30\;㎃/cm^2$ 조건에서 2시간 동안 양극산화 처리하였다. $TiO_2$ 나노튜브 형성 후 산화 피막층의 결정화를 유도하기 위해 $600^{\circ}C$에서 2시간 동안 열처리하였고, 표면활성도를 개선하기 위해 0.5 M $Na_2HPO_4$ 수용액 24시간 침적과 $Ca(OH)_2$ 포화 수용액에 5시간 침적을 시행하였다. 준비한 시편의 표면 반응성을 조사하기 위해 pH와 무기이온의 농도를 사람의 혈장과 유사하게 조절한 Hanks 용액 (H2387, Sigma Chemical Co., USA)에 2주간 침적하였다. 결과: 20 V에서의 양극산화처리로 직경 48.0 - 65.0 ㎚ 범위의 무정형의 $TiO_2$ 나노튜브가 전체 표면에 걸쳐서 균일하게 생성되는 양상을 보였다. $TiO_2$ 나노튜브는 $600^{\circ}C$에서 2시간 열처리 후 상대적으로 강한 anatase 피크와 함께 rutile 피크가 관찰되었다. $TiO_2$ 나노튜브의 표면활성도는 0.5 M $Na_2HPO_4$ 수용액 24시간 침적과 $Ca(OH)_2$ 포화수용액에 5시간 침적으로 개선되었다. 열처리와 전석회화 처리 후 SBF에 침적한 결과, $TiO_2$ rutile 피크의 상대적 강도는 크게 증가되었지만 HA의 석출은 저하되는 경향을 보였다. 결론: 이상의 결과로 미루어 볼 때, 양극산화 처리한 $TiO_2$ 나노튜브는 $600^{\circ}C$에서의 열처리에 의해 피막층이 안정화되고, 0.5 M $Na_2HPO_4$ 수용액 24시간 침적과 $Ca(OH)_2$ 포화수용액에 5시간 침적으로 표면에 인산칼슘층을 형성하는 것이 표면활성도를 개선하는데 유효함을 알 수 있었다.

• 대한치과보철학회지
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• 제45권1호
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• pp.85-97
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• 2007

Statement of problem: Recently, anodic oxidation of cp-titanium is a popular method for treatment of titanium implant surfaces. It is a relatively easy process, and the thickness, structure, composition, and the microstructure of the oxide layer can be variably modified. Moreover the biological properties of the oxide layer can be controlled. Purpose: In this study, the roughness, microstructure, crystal structure of the variously treated groups (current, voltage, frequency, electrolyte, thermal treatment) were evaluated. And the specimens were soaked in simulated body fluid (SBF) to evaluate the effects of the surface characteristics and the oxide layers on the bioactivity of the specimens which were directly related to bone formation and integration. Materials and methods: Surface treatments consisted of either anodization or anodization followed thermal treatment. Specimens were divided into seven groups, depending on their anodizing treatment conditions: constant current mode (350V for group 2), constant voltage mode (155V for group 3), 60 Hz pulse series (230V for group 4, 300V for group 5), and 1000 Hz pulse series (400V for group 6, 460V for group 7). Non-treated native surfaces were used as controls (group 1). In addition, for the purpose of evaluating the effects of thermal treatment, each group was heat treated by elevating the temperature by $5^{\circ}C$ per minute until $600^{\circ}C$ for 1 hour, and then bench cured. Using scanning electron microscope (SEM), porous oxide layers were observed on treated surfaces. The crystal structures and phases of titania were identified by thin-film x-ray diffractmeter (TF-XRD). Atomic force microscope (AFM) was used for roughness measurement (Sa, Sq). To evaluate bioactivity of modified titanium surfaces, each group was soaked in SBF for 168 hours (1 week), and then changed surface characteristics were analyzed by SEM and TF-XRD. Results: On basis of our findings, we concluded the following results. 1. Most groups showed morphologically porous structures. Except group 2, all groups showed fine to coarse convex structures, and the groups with superior quantity of oxide products showed superior morphology. 2. As a result of combined anodization and thermal treatment, there were no effects on composition of crystalline structure. But, heat treatment influenced the quantity of formation of the oxide products (rutile / anatase). 3. Roughness decreased in the order of groups 7,5,2,3,6,4,1 and there was statistical difference between group 7 and the others (p<0.05), but group 7 did not show any bioactivity within a week. 4. In groups that implanted ions (Ca/P) on the oxide layer through current and voltage control, showed superior morphology, and oxide products, but did not express any bioactivity within a week. 5. In group 3, the oxide layer was uniformly organized with rutile, with almost no titanium peak. And there were abnormally more [101] orientations of rutile crystalline structure, and bonelike apatite formation could be seen around these crystalline structures. Conclusion: As a result of control of various factors in anodization (current, voltage, frequency, electrolytes, thermal treatment), the surface morphology, micro-porosity, the 2nd phase formation, crystalline structure, thickness of the oxide layer could be modified. And even more, the bioactivity of the specimens in vitro could be induced. Thus anodic oxidation can be considered as an excellent surface treatment method that will able to not only control the physical properties but enhance the biological characteristics of the oxide layer. Furthermore, it is recommended in near future animal research to prove these results.