• 한국초전도ㆍ저온공학회논문지
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• 제10권1호
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• pp.15-18
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• 2008

To achieve high transport current without degradation under magnetic field, it is essential to artificially generate the pinning sites at which moving magnetic flux can be pinned. In this work, $ZrO_2$ nanodots were formed on the substrate surface using electro-spray deposition method. On top of the nanodots, the extended and effective pinning centers can be created. The positively charged Zr precursor solution was sprayed out from the needle using the corona discharge phenomena. Then, the sprayed precursor was deposited onto the negatively charged substrate surface followed by the heat treatment under the controlled atmosphere. Using the electrostatic force among the charged particles of precursor, evenly distributed and nano-sized dots were formed on the substrate surface. The size and density of the nanodots were studied by Atomic Force Microscopy. Also discussed are the effect of the deposition time and solution concentration on the size and density of the nanodot and processing variables in electro-spray method for the effective flux pinning centers in the superconducting films.

• 한국초전도ㆍ저온공학회논문지
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• 제10권2호
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• pp.12-15
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• 2008

Nano-sized dots have been formed on the buffered metal substrates using the novel approach of the electro-spray deposition, to modulate the substrate surface and induce the columnar defects in REBCO films grown on it. The $BaZrO_3$ precursor solution was synthesized and electro-sprayed out onto the negatively charged substrate surface. Using the electrostatic force, nano-sized dots can be grown and uniformly distributed on the buffered metal substrate. The height of BZO nanodots was observed above the 200nm, which are beneficial to induce the columnar defects onto the BZO as a seed. The density of BZO nanodots was also investigated and ${\sim}7.8/{\mu}m^2$ was obtained. As the deposition distance of electro-spray was shortened there was ${\sim}8times$ increase of density of nanodots. The optimization of process variables in electro-spray deposition are discussed in respect to the superconducting REBCO films processed by the Metal-Organic Deposition with the effective flux pinning properties.

• 한국가스학회지
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• 제5권1호
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• pp.52-59
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• 2001

LP가스 용접 용기의 가스 누출사고에 대한 통계적 분석을 통하여 사고 발생에 영향을 미치는 주된 요인을 조사하였다. 그 결과 대부분의 가스 누출은 용접부 국부부식에 따른 핀홀에 의한 누출이 가장 큰 비중을 차지하고 있다. 따라서, 본 논문에서는 2부구조 용기에서의 열처리조건의 문제점과 3부구조 용기의 T부위 터짐 현상에 의한 대책안을 제시하였다. 나아가, LP 가스 용기의 용접부 및 모재부에 대하여 산성비와 해수 분위기에서의 부식속도를 전기화학적 부식실험을 통하여 측정하였다. 또한, LP가스 용기의 제조공정중 분체도장 공정에 의한 도장막의 부착성 및 결함을 주사전자현미경을 통하여 분석하고 최적의 도장 두께를 제시하였다.

• 한국분무공학회지
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• 제7권2호
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• pp.7-15
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• 2002

A particle flow visualization, electrostatic charging measurement and separation of triboelectrically charged particles in the external electric field by a fluidized bed tribocharger are conducted for the removal of PVC particles from mixed waste plastics. The laboratory-scale triboelectrostatic separation system consists of the fluidized bed tribocharger, a separation chamber, a collection chamber and a controller. PVC and PET particles can be imparted negative and positive surface charges respectively due to the difference of triboelectric charging series between particles and particles in the fluidized bed tribocharger, and can be separated by passing them through an external electric field. To visualize these charged particles, He-Ne laser is used with cylindrical lenses to generate a sheet beam. In the charging measurement, the particle motion analysis system (PMAS), capable of determining particle velocity and diameter. is used to non-intrusively measure particle behavior in high strength electric field. The average charge-to-mass ratios of PVC and PET particles are $1.4\;and\;1.2{\mu}C/kg$, respectively. The highly concentrated PVC (91.9%) can be recovered with a yield of about 96.1% from the mixture of PVC and PET materials for a single-stage processing. The triboelectrostatic separation system using the fluidized tribocharger shows the potential to be an effective method for removing PVC from mixed plastics for waste plastic recycling.

• 대한환경공학회지
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• 제27권12호
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• pp.1292-1297
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• 2005

상수나 하수처리장에서 쓰이는 오존처리는 물질전달에 제약을 받는 공정임은 알려져왔다. 이런 물질전달의 한계를 극복하는 방법으로 매우 효과적인 것은 오존가스를 함유한 기포의 크기를 줄임으로써 물질전달에 필요한 접촉면적을 넓히는 것이다. 오존의 전달을 크게 하기 위한 방법으로서 본 연구에서는 전기장분사(Electrostatic spraying: ES)를 사용하였다. 실험에서는 ES와 기포발생판을 비교하였는데 ES실험에서는 전압을 0 kV에서 4 kV 범위까지 높여주어 물질전달효과를 살펴보았고 기공크기가 다른 두 가지 기포발생판(미세기공: 기공크기 $10{\sim}15{\mu}m$, 중간기공: 기공크기 $40{\sim}60{\mu}m$)을 사용하여 물질전달효율을 비교 분석 하였다. 물질전달효율은 시간의 경과에 따른 용존오존농도의 측정과 페놀의 산화시간으로 간접 계산하였다. 실험 결과 ES의 경우 전압을 0 kV에서 4 kV까지 올렸을 때 기포의 크기가 작아짐으로 인해 오존전달율을 약 40% 정도 향상시킬 수 있었다. 또한 ES와 기포발생판의 물질전달 비교실험에서 미세기공 기포발생판보다 4 kV의 ES가 더 효과적임을 알 수 있었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.84.2-84.2
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• 2010

PEMS (printed electro-mechanical system) is fabricated by means of various printing technologies. Passive and active components in 2D or 3D such as conducting lines, resistors, capacitors, inductors and TFT, which are printed with functional materials, can be classified in this category. And the issue of PEMS is applied to a R2R process in the manufacturing process. In many electro-devices, the vacuum process is used as the manufacturing process. However, the vacuum process has a problem: it is difficult to apply toa continuous process as a R2R printing process. In this paper, we propose an ESD (electro static deposition) printing process has been used to apply an organic solar cell of thin film forming. ESD is a method of liquid atomization by electrical forces, anelectrostatic atomizer sprays micro-drops from the solution injected into the capillary, with electrostatic force generated by electric potential of about tens of kV. ESD method is usable in the thin film coating process of organic materials and continuous process as a R2R manufacturing process. Therefore, we experiment the thin films forming of PEDOT:PSS layer and Active layer which consist of the P3HT:PCBM. The result of experiment, organic solar cell using ESD thin film coated method is occurred efficiency of about 1.4%. Also, the case of only used to ESD method in the active layer coating is occurred efficiency of about 1.86% as the applying a spin coating in the PEDOT:PSS layer. We can expect that ESD method is possible for continuous process to manufacture in the organic solar cell or OLED device.

• Journal of Ceramic Processing Research
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• 제18권11호
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• pp.810-814
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• 2017

Proton exchange membrane fuel cells (PEMFCs) are some of the most efficient electrochemical energy sources for transportation applications because of their clean, green, and high efficiency characteristics. The optimization of catalyst layer morphology is considered a feasible approach to achieve high performance of PEMFC membrane electrode assembly (MEA). In this work, we studied the effect of the solvent on the catalyst layer of PEMFC MEAs fabricated using the electrostatic spray deposition method. The catalyst ink comprised of Pt/C, a Nafion ionomer, and a solvent. Two types of solvent were used: isopropyl alcohol (IPA) and dimethylformamide (DMF). Compared with the catalyst layer prepared using IPA-based ink, the catalyst layer prepared with DMF-based ink had a dense structure because the DMF dispersed the Pt/C-Nafion agglomerates smaller and more homogeneously. The size distribution of the agglomerates in catalyst ink was confirmed through Dynamic Light Scattering (DLS) and the microstructure of the catalyst layer was compared using field emission scanning electron microscopy (FE-SEM). In addition, the electrochemical investigation was performed to evaluate the solvent effect on the fuel cell performance. The catalyst layer prepared with DMF-based ink significantly enhanced the cell performance (1.2 A cm-2 at 0.5 V) compared with that fabricated using IPA-based ink (0.5 A cm-2 at 0.5 V) due to the better dispersion and uniform agglomeration on the catalyst layer.

• 한국결정성장학회지
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• 제16권3호
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• pp.116-120
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• 2006

반도체 드라이 에처 시스템의 웨이퍼 정전기 척에 적용하기 위해 플라즈마 스프레이 방법으로 Al-60 계열 기판에 코팅한 $Al_2O_3$ 코팅 막의 특성을 조사하였다. 시편 뒷면에 냉각봉이 장착되었을 때와 없을 때, 용사거리와 분말공급량을 변형하면서 $Al_2O_3$ 막 코팅을 하여 시편을 제작 하였다. 시편 뒷면에 냉각봉이 없을 때는 크랙과 기공이 많이 발생하였다. 시편 뒷면에 냉각봉을 장착하고 분말공급량을 15g/min로 한 경우에 용사거리 60, 70, 80mm에 따른 $Al_2O_3$ 코팅에서는 크랙과 기공은 거의 찾아볼 수 없었다. 용사거리 변화에 따른 $Al_2O_3$ 막 코팅의 표면형태 변화는 없었다. 같은 공정조건에서 분말 공급량을 20g/min로 한 경우에도 크랙은 볼 수 없었으나 약간의 기공이 생겼고, 분말공급량을15g/min로 하였을 때 보다 작은 입자들이 많이 증착되었다. 시편 뒷면에 냉각봉이 없을 때가 시편 뒷면에 냉각봉이 장착된 경우에 비하여 증착 속도가 빨랐다.

• 플랜트 저널
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• 제18권1호
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• pp.50-54
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• 2022

미세먼지 배출 허용 기준이 강화됨에 따라 화력발전소, 제철소, 산업용 열병합 발전소 등 배가스 배출 시설의 미세먼지 제거를 위해 고효율 집진장치 수요가 급증하고 있다. 본 연구에서는 기존 전기집진기에 정전분무 기술을 도입하여 단점을 보완하고 성능을 향상시키는 연구를 진행 중이다. 정전분무는 매우 미세한 액적을 생성하는 목적으로 주로 사용되어왔지만, 집진을 목적으로 할 때는 그 유량이 10mL/min으로 65 ~ 200배에 달하는 고유량 조건이 필요하다. 고유량의 정전분무는 저유량과는 완전하게 다른 분무 형상이 나타나며 코로나 방전 사진 촬영, 그림자 촬영법 등 다양한 촬영을 통하여 이를 가시화하였다.

• 대한치과교정학회지
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• 제53권1호
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• pp.16-25
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• 2023

Objective: We aimed to evaluate the cell viability and antimicrobial effects of orthodontic bands coated with silver or zinc oxide nanoparticles (nano-Ag and nano-ZnO, respectively). Methods: In this experimental study, 30 orthodontic bands were divided into three groups (n = 10 each): control (uncoated band), Ag (silver-coated band), and ZnO (zinc oxide-coated band). The electrostatic spray-assisted vapor deposition method was used to coat orthodontic bands with nano-Ag or nano-ZnO. The biofilm inhibition test was used to assess the antimicrobial effectiveness of nano-Ag and nano-ZnO against Streptococcus mutans, Lactobacillus acidophilus, and Candida albicans. Biocompatibility tests were conducted using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. The groups were compared using oneway analysis of variance with a post-hoc test. Results: The Ag group showed a significantly higher reduction in the number of L. acidophilus, C. albicans, and S. mutans colonies than the ZnO group (p = 0.015, 0.003, and 0.005, respectively). Compared with the control group, the Ag group showed a 2-log₁₀ reduction in all the microorganisms' replication ability, but only S. mutants showed a 2-log₁₀ reduction in replication ability in the ZnO group. The lowest mean cell viability was observed in the Ag group, but the difference between the groups was insignificant (p > 0.05). Conclusions: Coating orthodontic bands with nano-ZnO or nano-Ag induced antimicrobial effects against oral pathogens. Among the nanoparticles, nano-Ag showed the best antimicrobial activity and nano-ZnO showed the highest biocompatibility.