• 한국안전학회지
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• 제19권1호
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• pp.77-80
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• 2004

The purpose of this study was to examine effects of combustion retardation for paper filter impregnated metal salts by measurement of extinguishing concentration, CO concentration, and limiting oxygen index(LOI, ASTM D 2863). And thermal stability analysis using DSC was carried out. In case of extinguishing concentration, $NH_4H_2PO_4$ showed excellent effect of combustion retardation. The result of LOI measurement showed that metal salts possessed good effect of combustion retardation. And thermal analysis using DSC showed that these metal salts possessed thermal stability. In case of CO concentration, CO concentration was increasing because of imperfect combustion process due to combustion retardation effect of metal salts.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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• pp.759-762
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• 2003

The epitaxially grown Mg-doped GaN thin film was prepared by MOCVD (Metal Organic Chemical Vapor Deposition) for a SAW(Surface Acoustic Wave) filter. Mg-doped GaN thin film had enough properties for a SAW filter which include crystallinity and morphology. The surface morphology and crystalline of the Mg-doped GaN thin films were characterized using AFM and an X-ray rocking curve. The SAW filter, which was fabricated by lift-off process and frequency response, was measured by HP 8753C network analyzer. Center frequency was 96.687 MHz and SAW velocity was 5801 m/s when wavelength(λ) was 60${\mu}{\textrm}{m}$. Insertion loss was over -10 dB, Q was factor over 200, and side lobe attenuation was over 22 dB which was suitable for use as a SAW filter. Electro-mechanical coupling coefficient (k$^2$) was calculated from the measured data. k$^2$ was from 1 % to 1.44 %. The fabricated SAW filter using Mg-doped GaN/sapphire structure has good qualities as a filter and will be used as a SAW filter for operating RF frequency.

• Nuclear Engineering and Technology
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• 제55권5호
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• pp.1830-1837
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• 2023

The thermal cutting of contaminated or activated metals during decommissioning nuclear power plants inevitably results in the release of radioactive aerosol. Since radioactive aerosols are pernicious particles that contribute to the internal dose of workers, air conditioning units with a HEPA filter are used to remove radioactive aerosols. However, a HEPA filter cannot be used permanently. This study evaluates the efficiency and lifetime of filters in actual metal cutting condition using a plasma arc cutter and a high-resolution aerosol detector. The number concentration and size distribution of aerosols from 6 nm to 10 ㎛ were measured on both the upstream and downstream sides of the filter. The total aerosol removal efficiency of HEPA filter satisfies the standard of removing at least 99.97% of 0.3 ㎛ airborne particles, even if the pressure drop increases due to dust feeding load. The pressure drop and particle size removal efficiency at 0.3 ㎛ of the HEPA filter were found to increase with repeated cutting experiments. By contrast, the efficiency of used HEPA filter reduced in removing nano-sized aerosols by up to 79.26%. Altogether, these results can be used to determine the performance guidance and replacement frequency of HEPA filters used in nuclear power plants.

• 멤브레인
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• 제32권1호
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• pp.66-73
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• 2022

본 연구에서는 stainless steel로 재질로 된 금속평막모듈을 이용하여 고플럭스가 유지되면서 처리수의 안정화 방안을 모색하였다. 이 모듈은 기공사이즈가 13 ㎛ 단위여서 플럭스가 60 LMH에서 100 LMH까지 고플럭스로 운전이 가능하다 그러나 SS가 초기 운전 시 30~50 ppm 정도 유출되지만 SS가 응집핵으로 작용하므로 응집이 가능하게 된다. 기존 고분자막 여과수는 응집핵이 없어서 coagulation은 되지만 floculation이 안되므로 추가적으로 응집보조제인 clay나 벤토나이트를 투여하게 되는데 본 연구에서는 이런 응집보조제 필요 없이 SS 누출만으로 floculation이 되므로 총인처리와 처리수질이 안정성을 도모하고자 하였다. 최종적으로 안정적인 처리수에 고플럭스가 가능한 Metal필터 운전이 MBR 시스템에서 적용가능한지 타당성을 연구하고자 하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 반도체재료
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• pp.30-33
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• 2001

Chemical mechanical polishing(CMP) process has been widely used to planarize dielectrics, which can apply to employed in integrated circuits for sub-micron technology. Despite the increased use of CMP process, it is difficult to accomplish the global planarization of free-defects in inter-level dielectrics (ILD). Especially, defects like micro-scratch lead to severe circuit failure, and affects yield. CMP slurries can contain particles exceeding $1{\mu}m$ size, which could cause micro-scratch on the wafer surface. The large particles in these slurries may be caused by particle agglomeration in slurry supply line. To reduce these defects, slurry filtration method has been recommended in oxide CMP. In this work, we have studied the effects of filtration and the defect trend as a function of polished wafer count using various filters in inter-metal dielectric(IMD)-CMP. The filter installation in CMP polisher could reduce defect after IMD-CMP. As a result of micro-scratches formation, it shows that slurry filter plays an important role in determining consumable pad lifetime.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권5호
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• pp.191-195
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• 2002

Chemical mechanical Polishing (CMP) process is widely used for the global planarization of inter-metal dielectric (IMD) layer and inter-layer dielectric (ILD) for deep sub-micron technology. However, as the IMD and ILD layer gets thinner, defects such as micro-scratch lead to severe circuit failure, which affect yield. In this paper, for the improvement of CMP process, deionized water (DIW) pressure, purified $N_2$ ($PN_2$) gas, point of use (POU) slurry filler and high spray bar (HSB) were installed. Our experimental results show that DW pressure and P$N_2$ gas factors were not related with removal rate, but edge hot-spot of patterned wafer had a serious relation. Also, the filter installation in CMP polisher could reduce defects after CMP process, it is shown that slurry filter plays an important role in determining consumable pad lifetime. The filter lifetime is dominated by the defects. However, the slurry filter is impossible to prevent defect-causing particles perfectly. Thus, we suggest that it is necessary to install the high spray bar of de-ionized water (DIW) with high pressure, to overcome the weak-point of slurry filter Finally, we could expect the improvements of throughput, yield and stability in the ULSI fabrication process.

• 센서학회지
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• 제33권1호
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• pp.48-55
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• 2024

Metal-oxide-based semiconductor gas sensors are widely used because of their advantages, such as high response and simple sensing mechanism. Recently, with the rapid progress in sensor networks, computing power, and microsystem technology, sensor applications are expanding to various fields, such as food quality control, environmental monitoring, healthcare, and artificial olfaction. Therefore, the development of highly selective gas sensors is crucial for practical applications. This article reviews the developments in novel sensor design consisting of sensing films and physical and chemical filters for highly selective gas sensing. Unlike conventional sensors, the sensor structures with filters can separate the sensing and catalytic reactions into independent processes, enabling selective and sensitive gas sensing. The main objectives of this study are directed at introducing the role of various filters in gas-sensing reactions and promising sensor applications. The highly selective gas sensors combined with a functional filter can open new pathways toward the advancement of high-performance gas sensors and electronic noses.

• 소성∙가공
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• 제14권5호
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• pp.473-476
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• 2005

The demand of on-chip total analyzing system with MEMS (micro electro mechanical system) bio/chemical sensor is rapidly increasing. In on-chip total analyzing system, to detect the bio/chemical products with submicron feature size, a filtration system with nano-filter is required. One of the conventional methods to fabricate nano-filter is to use direct patterning or RIE (reactive ion etching). However, those procedures are very costly and are not suitable fur mass production. In this study, we suggested new fabrication method for a nano-filter based on replication process, which is simple and low cost process. After the Si master was fabricated by laser interference lithography and reactive ion etching process, the polymeric mold was replicated by UV-imprint process. Metallic nano-filter was fabricated after removing the polymeric part of metal deposited polymeric mold. Finally, our fabrication method was applied to metallic nano-filter with $1{\mu}m$ pitch size and $0.4{\mu}m$ hole size for bacteria sensor application.

• 한국대기환경학회지
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• 제19권3호
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• pp.297-306
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• 2003

Works were focused on back pressure characteristics of ceramic fiber filter on DPF (Diesel Particulate Filter) system and experiments were performed to select appropriate filter which can filter particulates. Filters were installed on metal -support tube which has openings for exhaust gas flow. Ceramic fiber filters with high specific surface area and adequate high temperature strength are commercially available for filtration of diesel particulates and in -situ hot regeneration. Thus, ceramic blanket and ceramic board which are used as insulating media were applied to filter and filtration apparatus was installed on exhaust gas line connected to 2.0 L diesel engine. Alternating filter structure to adapt DPF system, collection efficiency test of diesel particulates was measured. In case of ceramic blanket, pressure drop was low, caused by the destruction of soft structures. Also, particulate collection efficiency was decreased depending on loading time. In case of ceramic board, structure design was altered to reduce back pressure on DPF system. Structure design was altered to induce Z-flow by making 10 mm and 5 mm holes on the surface of media. Alteration of 5 mm hole showed that media have low back pressure but particulate collection efficiency was 77%, while 10 mm hole showed that of 90%.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2001년도 추계 학술발표회 논문집
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• pp.279-284
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• 2001