• JSTS:Journal of Semiconductor Technology and Science
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• 제8권2호
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• pp.121-127
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• 2008

This paper presents design and fabrication of optimized geometry structure of electrostatic inkjet head. In order to verify effect of geometry shape, we simulate electric field intensity according to the head structure. The electric field strength increases linearly with increasing height of the micro nozzle. As the nozzle diameter decreases, the electric field along the periphery of the meniscus can be more concentrated. We design and fabricate the electrostatic inkjet heads, hole type and pole type, with optimized structure. It was fabricated using thick-thermal oxidation and silicon micromachining technique such as the deep reactive ion etching (DRIE) and chemical wet etching process. It is verified experimentally that the use of the MEMS inkjet head allows a stable and sustainable micro-dripping mode of droplet ejection. A stable micro dripping mode of ejection is observed under the voltages 2.5 kV and droplet diameter is $10\;{\mu}m$.

• 한국환경과학회지
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• 제23권11호
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• pp.1953-1961
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• 2014

Increasing public concerns over odors and air regulations necessitates the remediation of a wide range of odor substances for industrial and indoor purpose. Currently, the wet scrubbing technique by neutralization using oils is being used to treat odor substances such as Ammonia($NH_3$), Methyl Mercaptan($CH_3SH$), Hydrogen Sulfide($H_2S$), Methylamine($CH_3NH_2$), Acetaldehyde($CH_3CHO$). The chemical analysis is performed to analyze the composition of an Arctium Lappa Root extract by VOC analyzer(Phocheck 5000Ex, ION SCIENCE co.) The objectives of the this study are to clarify the possibility of the neutralization of odors sprayed in the fixed bed and determine the removal efficiencies for different input odor concentrations. It is found that Ammonia($NH_3$), Methyl Mercaptan($CH_3SH$), Hydrogen Sulfide($H_2S$), Methylamine($CH_3NH_2$), Acetaldehyde($CH_3CHO$) are significantly removed and their removal efficiencies are higher than 98%. The kitchen detergent with Arctium Lappa Root extract showed excellent removal efficiencies of odor substances and high possibility for the development of kitchen detergent with odor removal.

• 한국전기전자재료학회논문지
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• 제18권12호
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• pp.1075-1079
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• 2005

The Pseudo MOSFET measurements technique has been used for the electrical characterization of the nano SOI wafer. Silicon islands for the Pseudo MOSFET measurements were fabricated by selective etching of surface silicon film with dry or wet etching to examine the effects of the etching process on the device properties. The characteristics of the Pseudo MOSFET were not changed greatly in the case of thick SOI film which was 205 nm. However the characteristics of the device were dependent on etching process in the case of less than 100 nm thick SOI film. The sub 100 nm SOI was obtained by thinning the silicon film of standard thick SOI wafer. The thickness of SOI film was varied from 88 nm to 44 nm by chemical etching. The etching process effects on the properties of pseudo MOSFET characteristics, such as mobility, turn-on voltage, and drain current transient. The etching Process dependency is greater in the thinner SOI wafer.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.912-915
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• 2004

Inductors material utilized in the downsizing passive devices and Rf components requires the physical and electrical properties at given area such as inductors thickness reduction, inductance and q-factor increase, low leakage current and thermal stability. In this study, Spiral inductors on the $SiO_2/Si$(100) substrate were fabricated by the magnetron sputtering method. Cu thin film with the thickness of $2{\mu}m$ was deposited on the substrate. Also we fabricated square inductors through the wet chemical etching technique. The inductors are completely specified by the turn width and the spacing between spirals. Both the width and spacing between spirals were varied from 10 to $60{\mu}m$ and from 20 to $70{\mu}m$, respectively. Inductance and Q factor dependent on the RF frequency were investigated to analyze performance of inductor arrays

• 한국광학회지
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• 제6권2호
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• pp.148-155
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• 1995

저손실의 단일모드 $Al_{0.042}Ga_{0.958}As/GaAs/Al_{0.042}Ga_{0.958}As$ strip-loaded 도파로들이 유효굴절률 방법으로 설계되고 MOCVD 성장기법과 화학적인 습식 식각방법으로 제작되었다. 제작된 도파로의 전파손실과 도파로 단면의 반사율은 $1.31{\mu}m$ 파장에서 Fabry-Perot 공명방법과 연속적인 절단 실험을 이용하여 측정되었다. 실험결과 폭이 $ w=4.1{\mu}m$인 직선 도파로에 대해 전파손실은 0.62dB/cm로 작았으며 도파로의 반사율은 0.299가 되었다.

• 한국전기전자재료학회논문지
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• 제16권8호
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• pp.700-704
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• 2003

This paper describes on characteristics of 2" 3C-SiC wafer bonding using PECVD (plasma enhanced chemical vapor deposition) oxide and HF (hydrofluoride acid) for SiCOI (SiC-on-Insulator) structures and MEMS (micro-electro-mechanical system) applications. In this work, insulator layers were formed on a heteroepitaxial 3C-SiC film grown on a Si (001) wafer by thermal wet oxidation and PECVD process, successively. The pre-bonding of two polished PECVD oxide layers made the surface activation in HF and bonded under applied pressure. The bonding characteristics were evaluated by the effect of HF concentration used in the surface treatment on the roughness of the oxide and pre-bonding strength. Hydrophilic character of the oxidized 3C-SiC film surface was investigated by ATR-FTIR (attenuated total reflection Fourier transformed infrared spectroscopy). The root-mean-square suface roughness of the oxidized SiC layers was measured by AFM (atomic force microscope). The strength of the bond was measured by tensile strength meter. The bonded interface was also analyzed by IR camera and SEM (scanning electron microscope), and there are no bubbles or cavities in the bonding interface. The bonding strength initially increases with increasing HF concentration and reaches the maximum value at 2.0 ％ and then decreases. These results indicate that the 3C-SiC wafer direct bonding technique will offers significant advantages in the harsh MEMS applications.ions.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.3-4
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• 2005

The Pseudo-MOSFET measurements technique has been used for the electrical characterization of the nano SOL Silicon islands for the Pseudo-MOS measurements were fabricated by selective etching of surface silicon film with dry or wet etching to examine the effects of the etching process on the device properties. The characteristics of the Pseudo-MOS was not changed greatly in the case of thick SOI film which was 205 nm. However the characteristics of the device was dependent on etching process in the case of less than 100 nm thick SOI film. The sub 100nm SOI was obtained by thinning the silicon film of standard thick SOI. The thickness of SOI film was varied from 88 nm to 44 nm by chemical etching. The etching process effects on the properties of pseudo-MOSFET characteristics, such as mobility, turn-on voltage, and drain current transient. The etching process dependency is greater in the thinner SOI and related to original SOI wafer quality.

• Advances in nano research
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• 제12권4호
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• pp.415-426
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• 2022

Nickel substituted cobalt-zinc ferrite nanoparticles with composition Co_0.5Zn_0.5Ni_xFe_2-xO₄ (x = 0.25, 0.5, 0.75, 1.0) were synthesized using a wet chemical method named citrate precursor method. Various characterizations of the prepared nanoferrites were done using X-ray powder diffractometry (XRD), Scanning electron microscopy (SEM), UV visible spectroscopy and Fourier transform spectroscopy technique (FT-IR). XRD confirmed the formation of cubic spinel structure of the samples with single phase having one characteristic peak at (311). The value of optical band gap (E_g) was found to decrease with Ni substitution and have values in the range 2.30eV to 1.69eV. A Fenton-type system was created by photocatalytic activity using source of visible light for removal of methylene blue dye. Observations revealed increase in the degradation of methylene blue dye with increasing nickel content in the samples. The degradation percentage was increased from 77.32% for x = 0.25 to 90.16% for x = 1.0 in one hour under the irradiation of visible light. Also, the degradation process was found to have pseudo first order kinetics model. Hence, it can be observed that synthesized nickel doped cobalt-zinc ferrites have good capability for water purification and its degradation efficiency enhanced with increase in nickel concentration.

• 한국습지학회지
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• 제25권4호
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• pp.221-229
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• 2023

수도권에 일 약 8백만톤의 물을 취수하여 공급하는 팔당호는 수질보전정책 시행으로 BOD(Biochemical Oxygen Demand)1.1mg/L를 달성하였으나 난분해성 물질을 포함하는 COD(Chemical Oxygen Demand) 항목은 점점 증가하는 양상을 보였다. 난분해성 유기물질의 상수원 유입은 잠재적인 BOD의 증가, 수돗물의 냄새와 맛 유발, THM(Trihalomethane) 발생 증가, 조류 증식을 일으키며 유해 난분해성 미량오염물질이 잔류할 경우 수생 환경에서 내분비 교란과 항생제 내성과 같은 현상을 유발한다. 본 연구에서는 팔당호의 난분해성 유기물질 관리를 위해 팔당호와 팔당호 상류의 점 오염원과 비점오염원의 난분해성 유기물질 유출 농도를 파악하기 위한 모니터링을 실시하였다. 지역별 난분해성 유기물질 유출 농도를 비교하고 하수처리장에서의 제거율을 파악하였다. 또한 피어슨 상관성 분석 기법을 사용해 유기물질 지표와 선행건기일수, 선·선행건기일수간 상관성 분석을 실시하였다. 하천과 팔당호의 난분해성 유기물질 농도는 유사한 양상을 보였다. 하수처리장 유출수는 하천과 팔당호보다는 높은 농도를 보였으며, 유입수와 유출수 농도의 비교 결과 하수처리장에서 난분해성 유기물질 제거율은 65.73%였다. 난분해성 유기물질 유출 농도와 선행건기일수, 선·선행건기일수 사이에서는 유의미한 상관성이 나타나지 않았다. 이는 데이터 부족으로 판단되며 장기적인 모니터링으로 데이터 축적이 필요하다 사료된다.