• 청정기술
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• 제18권2호
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• pp.209-215
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• 2012

분말활성탄과 제올라이트가 담지된 폴리우레탄 담체를 충진한 파일롯 규모의 바이오필터를 이용하여 암모니아와 황화수소의 처리 성능을 평가하였다. 약 10개월간 하수처리장 슬러지 농축조에서 발생하는 악취를 대상으로 바이오필터 유입 암모니아 농도는 0.1~1.5 $ppm_v$, 황화수소 농도는 2~20 $ppm_v$ 범위에서 운전되었다. 바이오필터의 공탑체류시간 3.6~5초 범위에서 초기 순응기간을 제외하고는 거의 모든 경우 100%에 가까운 악취 제거율을 보여주었다. 바이오필터에서의 기체흐름에 의한 압력손실도 매우 낮아 10개월 동안 최대 31 mm $H_2O$ 정도의 차압이 발생하였다. 이것은 본 연구에 이용된 바이오필터의 막힘이나 담체의 압착 현상이 거의 일어나지 않아 장기간의 운전에도 안정성을 확인할 수 있었다. 담체에 부착하여 서식하는 미생물군집은 바이오필터의 처리 성능에 중요한 영향을 미치는데 특히 암모니아나 황화수소를 제거하기 위한 암모니아 산화균과 황산화균의 분포가 중요하다. FISH (Fluorescence in Situ Hybridization) 방법으로 확인한 결과 질산화를 주관하는 암모니아 산화균인 Nitrosomonas sp.와 황산화균인 Thiobacillus ferroxidans가 검출되었다. 또한 바이오필터의 운전기간이 길어질수록, 그리고 악취의 유입부분이 유출부분에 비해 미생물 분포량이 더 많음을 확인하였다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2013년도 자성 및 자성재료 국제학술대회
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• pp.95-95
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• 2013

The NdFeB magnet can be classified into the sintered magnet and bonded magnet. The former has superior magnet characteristics but the degree of freedom in shape is highly restricted, whereas the latter has a high degree of freedom, but its magnet characteristics are inferior to the former. When a NdFeB magnet is used at the elevated temperature, part of Nd must be replaced with a high priced Dy to increase its coercive force. For these reasons, a Dy free and high performance NdFeB bonded magnet is desired strongly. The author successfully developed a Dy free NdFeB anisotropic bonded magnet based on discovery of new phenomena called as d-HDDR reaction and its mass production process such as a thermally balanced hydrogen reaction furnace, micro capsuled powder, compression molding / injection molding under magnetic field, magnetic die and so on. Applied to DC brush seat motor for automotive use, the motor has become 50% small in size and weight. The commercialization of a half sized motor for automotive use has been realized up to the market share of 30%. At present, its commercialization is extending to various types of motors such as power tool, ABS motor, wiper motor, window motor, electric bike power motor, and compressor motor. It is expected that the applications will be increasingly enlarged to EV motor, wind generator, EPS motor, washing machine, and glass cutting machine. This innovative technology has realized Dy free high performance magnet and mudt make big contribution to not only rare element strategies but also energy conservation.

• 대한기계학회논문집B
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• 제39권12호
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• pp.945-952
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• 2015

본 연구에서는 바이오매스 합성가스를 모사하여 합성가스의 주요성분에 따른 자착화 특성을 실험 및 수치적으로 고찰하였으며, 온도, 혼합물의 조성, 압력의 변화가 자착화 특성에 미치는 영향을 분석하였다. 충격파관(Shock Tube)을 이용하여 모사 합성가스의 점화지연 시간을 측정하였고, 수치해석은 실험결과 검증과 연소과정 중 중간화학종 분석을 위해 상용프로그램인 CHEMKIN-PRO를 사용하였다. 모든 온도 조건에서 혼합물 내의 수소의 몰 비율이 증가함에 따라 점화지연 시간이 감소하는 현상을 확인할 수 있었다. 1150K 이상의 온도 조건에서 압력이 증가함에 따라 점화지연 시간이 감소하는 현상을 확인 할 수 있었다. 하지만 1150K 이하의 온도 조건에서는 압력이 증가함에 따라 점화지연 시간이 증가하는 현상을 확인할 수 있었다.

• Nuclear Engineering and Technology
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• 제52권3호
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• pp.597-609
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• 2020

Accident Tolerant Fuels have been widely studied since the Fukushima-Daiichi accident in 2011 as one of the options on how to further enhance the safety of nuclear power plants. Deposition of protective coatings on nuclear fuel claddings has been considered as a near-term concept that will reduce the high-temperature oxidation rate and enhance accidental tolerance of the cladding while providing additional benefits during normal operation and transients. This study focuses on experimental testing of Zr-based alloys coated with Cr-based coatings using Physical Vapour Deposition. The results of long-term corrosion tests, as well as tests simulating postulated accidents, are presented. Zr-1%Nb alloy used as nuclear fuel cladding serves as a substrate and Cr, CrN, Cr_xN_y layers are deposited by unbalanced magnetron sputtering and reactive magnetron sputtering. The deposition procedures are optimized in order to improve coating properties. Coated as well as reference uncoated samples were experimentally tested. The presented results include standard long-term corrosion tests at 360℃ in WWER water chemistry, burst (creep) tests and mainly single and double-sided high-temperature steam oxidation tests between 1000 and 1400℃ related to postulated Loss-of-coolant accident and Design extension conditions. Coated and reference samples were characterized pre- and post-testing using mechanical testing (microhardness, ring compression test), Thermal Evolved Gas Analysis analysis (hydrogen, oxygen concentration), optical microscopy, scanning electron microscopy (EDS, WDS, EBSD) and X-ray diffraction.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.198-201
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• 2001

Porous structures of aluminum foam have been studied by using return aluminum scrap. The apparent foam shape, foam height, density, pore size and their distributions in various section areas of the experimental samples have been investigated. The sample have been cast into metallic mold, using aluminum foam prepared from a precursor based on pure Al ingot and return aluminum scrap mixed with various amounts of 1-2wt% increasing viscosity and foam agent materials. The process provides for flexibility in design of foam structures via relatively easy control over the amount of hydrogen evolution and the drainage processes which occur during foam formation. This is facilitated by manipulating parameters such as the foaming agent, thermal histories during solidification and mix melt viscosities. A metal for producing the foamed are decomposing a foaming agent in a molten metal such that there is an initial and a subsequent expansion due to foaming agent. It has been found that the Al porous foaming with variation amount of 1∼2wt% foam agent and at 2min holding time, which melting temperature has appeared homogeneous pore size at 650∼700$^{\circ}C$. The compression strength were 10-13 kg/min at 125ppi, and increased by higher pore density. The acoustical performance of the panel made with the foamed aluminum is considerably improved; its absorption coefficient shows NRC 0.6-0.8. It has been found that the Al foam is very preferable for the compactness of the thermal system.

• Korean Chemical Engineering Research
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• 제59권1호
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• pp.6-10
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• 2021

PEMFC(Proton Exchange Membrane Fuel Cell) 고분자 막의 shorting 저항(Shorting Resistance, SR)은 고분자 막의 내구성에 관한 중요한 지표다. SR이 감소하면 shorting 전류(Shorting Current, SC)가 증가하여 내구성과 성능이 감소하고, SR이 약 0.1 kΩ·㎠ 이하가 되면 shorting이 발생하여 온도가 급상승하고 MEA(Membrane Electrode Assembly)를 연소시켜 스택 구동이 종료된다. Shorting 현상을 방지하기 위해서는 SR을 제어해야 하므로 SR에 영향을 주는 조건들에 대해서 연구하였다. SR 측정방법들에서도 차이가 있어서 DOE(Department of Energy)와 NEDO(New Energy and Industrial Technology Development Organization) 방법을 개선한 SR 측정법을 제시하였다. 상대습도와 온도, 셀 체결 압이 상승하면 SR이 감소함을 확인하였다. 고분자 막의 가속내구 평가과정에서 마지막 단계에서 SR이 0.1 kΩ·㎠ 이하로 급감해 수소투과전류밀도가 15 mA/㎠ 이상이 되었고, 이 MEA를 해체 후 SEM(Scanning Electron Microscope) 분석한 결과 고분자 막 내부에 백금이 많이 분포함을 보였다.

• 한국지반신소재학회논문집
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• 제16권1호
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• pp.31-39
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• 2017

본 연구에서는 중금속 오염지반을 정화하기 위한 향상제로 친환경 재료인 나노버블수를 적용하기 위한 기초 연구를 수행하였다. 수소 나노버블을 제조하여 입도분석과 제타 포텐셜 측정을 통해 장기 생존성을 평가하였다. 제조된 나노버블수를 회분식 탈착실험에 적용하여 구리 오염토양에 대한 나노버블수의 정화 효과를 증류수와 비교하여 분석하였다. 가압용해식 나노버블 제조 장치를 통해 제조한 나노버블은 최소 14일간 존재함을 알 수 있었다. 또한 구리 오염 토양에 대한 회분식 탈착실험을 수행한 결과, 토양 종류에 관계없이 나노버블수의 제거효율은 전반적으로 증류수보다 높았으며 고액비와 반응시간에 비례하여 증가하였다. pH 변화에 따라 사질토는 산성 측에서 제거 효율이 높게 나타났으나 점성토는 그 차이가 다소 낮았다. 실험 결과를 통해 나노버블의 구리 탈착 효과는 나노버블의 큰 비표면적과 제타 포텐셜에 기인하여 전반적으로 우수하게 나타난 것으로 판단된다. 따라서 본 연구를 바탕으로 나노버블수의 중금속 제거 효과를 확인하였으며 이를 토양정화의 향상제로 적용하여 친환경적인 정화공법으로 활용될 수 있을 것으로 기대된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1998년도 제14회 학술발표회 논문개요집
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• pp.120-120
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• 1998

Boron nitride (BN) films have attracted a growing interest for a variety of t technological applications due to their excellent characteristics, namely hardness, c chemical inertness, and dielectrical behavior, etc. There are two crystalline phases 1551; of BN that are analogous to phases of carbon. Hexagonal boron nitride (h-BN) has a a layered s$\sigma$ucture which is spz-bonded structure similar to that of graphite, and is t the stable ordered phase at ambient conditions. Cubic boron nitride (c-BN) has a z zinc blende structure with sp3-bonding like as diamond, 따ld is the metastable phase a at ambient conditions. Among of their prototypes, especially 삼Ie c-BN is an i interesting material because it has almost the same hardness and thermal c conductivity as di없nond. C Conventionally, significant progress has been made in the experimental t techniques for synthesizing BN films using various of the physical vapor deposition 밍ld chemical vapor deposition. But, the major disadvantage of c-BN films is that t they are much more difficult to synthesize than h-BN films due to its narrow s stability phase region, high compression stress, and problem of nitrogen source c control. Recent studies of the metalorganic chemical vapor deposition (MOCVD) of I III - V compound have established that a molecular level understanding of the d deposition process is mandatory in controlling the selectivity parameters. This led t to the concept of using a single source organometallic precursor, having the c constituent elements in stoichiometric ratio, for MOCVD growth of 삼Ie required b binary compound. I In this study, therefore, we have been carried out the growth of h-BN thin f films on silicon substrates using a single source precursors. Polycrystalline h-BN t thin films were deposited on silicon in the temperature range of $\alpha$)() - 900 $^{\circ}$C from t the organometallic precursors of Boron-Triethylamine complex, (CZHs)3N:BRJ, and T Tris(dimethylamino)Borane, [CH3}zNhB, by supersonic molecular jet and remote p plasma assisted MOCVD. Hydrogen was used as carrier gas, and additional nitrogen w was supplied by either aDlIDonia through a nozzle, or nitrogen via a remote plasma. T The as-grown films were characterized by Fourier transform infrared spectroscopy, x x-ray pthotoelectron spectroscopy, Auger electron spectroscopy, x-ray diffraction, t transmission electron diffraction, optical transmission, and atomic force microscopy.roscopy.