• Title/Summary/Keyword: $N_2$ flow rate

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교대연속유입식 SBR 공정을 이용한 하수중의 질소 및 인 제거 (Nitrogen and Phosphorus Removal in Domestic Wastewater using SBR Process with Flow Changing Continuous Feed and Cyclic Draw)

  • 서인석;김홍석;김연권;김지연
    • 한국물환경학회지
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    • 제22권2호
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    • pp.203-208
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    • 2006
  • A continuous feed and cyclic draw SBR process was developed to overcome flow rate fluctuation and to maximize organic matters utilization efficiency for nitrogen and phosphorus removal. The developed SBR process was operated with two parallel reactors. Influent was supplied to one reactor which was not obligately aerated. At the same time, the other reactor was just aerated without supplying influent. In addition this mode was changed periodically. Cycle time was 6hr and aeration time ratio($t_{aer}/t_{total}$) was 0.33, respectively. $COD_{cr}$ and SS removal efficiencies of 95% or higher were achieved. Nitrogen removal was so greatly influenced by influent $COD_{cr}/T-N$ ratio. At influent $COD_{cr}/T-N$ ratio of 5.7, removal efficiencies of ammonia-N, T-N and T-P were 96%, 78% and 55%, respectively. Influent $COD_{cr}/T-N$ of 4 or higher ratio was necessary to achieve 60% or higher nitrogen removal. Organic matters of influent was efficiently utilized in denitrification reaction and consumed COD has a good correlation with removed T-N(about 6.5 mgCOD/mgTN). Continuous feed and cyclic draw SBR process could be one of alternative processes for the removal of nutrients in rural area where $COD_{cr}/T-N$ ratio was low and fluctuation of flow rate was severe.

고선택비 인산공정에서의 식각율 향상과 SiO2 재성장에 관한 연구 (Study on Improvement of Etch Rate and SiO2 Regrowth in High Selectivity Phosphoric Acid Process)

  • 이승훈;모성원;이양호;배정현
    • 한국재료학회지
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    • 제28권12호
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    • pp.709-713
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    • 2018
  • To improve the etch rate of $Si_3N_4$ thin film, $H_2SiF_6$ is added to increase etching rate by more than two times. $SiO_3H_2$ is gradually added to obtain a selectivity of 170: 1 at 600 ppm. Moreover, when $SiO_3H_2$ is added, the etching rate of the $SiO_2$ thin film increases in proportion to the radius of the wafer. In $Si_3N_4$ thin film, there is no difference in the etching rate according to the position. However, in the $SiO_2$ thin film, the etching rate increases in proportion to the radius. At the center of the wafer, the re-growth phenomenon is confirmed at a specific concentration or above. The difference in etch rates of $SiO_2$ thin films and the reason for regrowth at these positions are interpreted as the result of the flow rate of the chemical solution replaced with fresh solution.

목 안정화와 호흡 재교육 운동이 만성 뇌졸중 환자의 목 깊은 굽힘근육의 두께, 노력성 폐활량과 최대 기침 유량에 미치는 효과 (Effects of the Neck Stabilizing Exercise Combined With the Respiratory Reeducation Exercise on Deep Neck Flexor Thickness, Forced Vital Capacity and Peak Cough Flow in Patients With Stroke)

  • 이명효;황보각
    • 한국전문물리치료학회지
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    • 제22권1호
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    • pp.19-29
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    • 2015
  • Impaired respiratory function is common in patients with stroke. The purpose of this study were to investigate the effectiveness of exercises and to assess forced vital capacity and peak cough flow after completion of neck stabilizing and respiratory reeducation exercises (combining diaphragmatic breathing and pursed-lip breathing exercises). The 45 participants were randomly assigned to an experimental group 1 ($n_1=15$), experimental group 2 ($n_2=15$), and a control group ($n_3=15$). All subjects performed conservative physical therapy for 30 minutes. Experimental group 1 undertook the neck stabilizing exercise and the respiratory reeducation exercise. Experimental group 2 undertook the respiratory reeducation exercise. Additional exercise did not exceed 30 minutes, five times a week for six weeks. The subjects were assessed for deep neck flexor thickness and breathing function (forced vital capacity, forced expiratory volume at one second, forced expiratory volume at one second/forced vital capacity, peak expiratory flow, and manual assisted peak cough flow) at pre-post value. The results of this study were as follows. Experimental group 1 showed a significant increase only in deep neck flexor thickness change rate (p<.05). All groups showed significant increases in forced vital capacity, forced expiratory volume at one second, and peak expiratory flow in pre-post measurement (p<.05). Experimental groups 1 and 2 showed an increase in manual assisted peak cough flow in pre-post measurement (p<.05). There was no significant difference between experimental group 1 and experimental group 2, but experimental group 1 improved more than experimental group 2 in respiratory function as a whole. In conclusion, these findings suggest that the neck stabilizing exercise in combination with the respiratory reeducation exercise can improve forced vital capacity and peak cough flow in patients with stroke.

축방향 2단 다공체 내 N2로 과다 희석된 CH4-O2 화염의 안정화에 관한 실험적 연구 (Experimental Investigation on the Highly N2-diluted CH4-O2 Flame Stabilization in an Axially Two-section Porous Medium)

  • 김승곤;이대근;노동순;고창복
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2013년도 제46회 KOSCO SYMPOSIUM 초록집
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    • pp.45-46
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    • 2013
  • Stabilization characteristics of highly $N_2$-diluted $CH_4-O_2$ flame in an axially two-section porous inert medium were experimentally investigated for its application to the waste gas scrubber in semiconductor manufacturing processes. The flame behaviors were observed with respect to the fuel and $N_2$ flow rates and the equivalence ratios. As a result, four kinds of flame behaviors such as stable, flashback crossing the interface, blowout and sudden extinction were observed. It was also found that there exists two flame regime divided by a critical fuel flow rate. In addition, the flame stability was discussed based on the $N_2$ index which means the abatement capacity of our combustor in scrubbing the waste gas from the semiconductor processes.

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단상조직을 갖는 Cu-Zn합금의 고온강도에 미치는 변형속도와 온도의 영향 (Effects of Strain Rate and Temperature on the Hot Strength for Single Phase Cu-Zn Alloy)

  • 권용환;유연철
    • 소성∙가공
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    • 제4권2호
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    • pp.159-168
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    • 1995
  • The torsion tests in the range of $550~800^{\circ}C$, $5.0{\times}10^{-3}~5.0{\times}10^0/sec$ were performed to study the effects of strain rate$(\.{\varepsilon})$ and temperature(T) on the hot strength of Cu-Zn alloy. High temperature flow stresses of this alloy increased with increasing $\.{\varepsilon}$ and/or decreasing T, and than the more grain refinement could be obtained. The flow curves exhibited a peak followed by a steady steady state regime as a result of dynamic recrystallization. The hot strength dependence of $\.{\varepsilon}$ and T was described by a hyperbolic sine law, $\.{\varepsilon}=A(sinh0.017{\sigma})^4.81$exp(-216KJ/mol). Hot strength could be reduced at the arbitary condition, $\.{\varepsilon}$ and T, by constitutive parameter Z(Zenner-Hollomon parameter), $Z=A(sinh{\alpha}{\sigma})^n=\.{\varepsilon}$exp(Q/RT).

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시뮬레이션을 이용한 개별사무공간의 살균공조시스템 연구 (A Study of air Sterilization System in Personalized Office Using Simulation)

  • 최상곤
    • 설비공학논문집
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    • 제22권6호
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    • pp.353-360
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    • 2010
  • Recently H1N1(swine flu) and SARS has been infected widely in the world; we have to care about germs and virus in indoor air environment. The air sterilization system investigated in this study allows occupants to turn on/off and to control the incoming air speed and direction. To predict the performance of air sterilization system without real experiment, a simulation is considered to compare and analyze the performance of the air sterilization systems in a typical office space. Multiple system parameters including volume flow rate and velocity of supply air were varied and investigated during the simulation. The investigation result shows that difference (between simulation and experiment) was about 3.5% in case of minimum air flow rate and about 0.2% in case of maximum air flow rate. The results indicate that multi-zone simulation technique can be used to predict the performance of a sterilization system in personalized office.

부력 효과의 최소화를 통한 대향류 확산화염 소화거동에 관한 실험적 연구 (Experimental Study on Extinction Behavior in Buoyancy-minimized Counterflow Diffusion Flame)

  • 정용호;박정;권오붕;윤진한;길상인;김영주
    • 한국연소학회지
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    • 제17권4호
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    • pp.38-43
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    • 2012
  • Experimental study was conducted to elucidate flame extinction phenomena in counterflow flame. Using a curtain helium flow significantly reduced buoyancy such that the flame can be positioned at the center between the upper and lower nozzles even at the velocity ratio of 1.0. The curves of critical diluent mole fraction versus global strain rate have C-shapes. The flame oscillation was observed prior to low strain rate flame extinction at both flame conditions with and without minimizing buoyancy force. The results show that, at low strain rate flame, the self-excitation frequency with the order of 1.0 Hz in the case of utilizing pure helium gradually decreases in increase of $N_2$ mole fraction in the curtain flow, meaning that buoyancy suppresses the self-excitation of the outer edge flame.

r면 사파이어 위에 HVPE로 성장된 a면 GaN 에피층의 성장온도 효과 및 1000℃에서의 V/III족 비의 효과 (The effects of growth temperatures and V/III ratios at 1000℃ for a-plane GaN epi-layer on r-plane sapphire grown by HVPE)

  • 하주형;박미선;이원재;최영준;이혜용
    • 한국결정성장학회지
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    • 제25권2호
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    • pp.56-61
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    • 2015
  • Ga source 채널의 HCl flow가 700 sccm, 그리고 V/III족 비가 10으로 고정되었을 때, r-면 사파이어 위에 HVPE로 성장된 a-면 GaN 에피층 특성에 대한 성장 온도 영향을 연구하였다. 추가적으로 성장온도가 $1000^{\circ}C$, 그리고 Ga source 채널의 HCl flow가 700 sccm으로 고정되었을 때, 공급가스에 대한 V/III족 비 영향에 대하여 연구하였다. 성장온도가 높아지면서, a-면 GaN 에피층에 대한 (11-20) 면의 Rocking curve(RC)의 반치폭 값이 감소하였고 a-면 GaN 에피층의 성장두께는 증가하였다. $1000^{\circ}C$에서 V/III족 비가 높아짐에 따라, (11-20) 면의 RC의 반치폭 값이 감소하였고, a-면 GaN 에피층의 성장두께가 증가하였다. $1000^{\circ}C$와 V/III족 비=10에서 성장된 a-면 GaN 에피층이 (11-20) 면에서 가장 낮은 RC 반치폭인 734 arcsec을 보이며, RC측정을 통한 (11-20) 면의 방위각 가장 작은 영향을 보여준다.

수소 가스를 첨가한 글라이딩 아크 플라즈마의 과불화화합물(PFCs) 가스 분해 특성 (Decomposition Characteristics of Perfluorocompounds(PFCs) Gas through Gliding Arc Plasma with Hydrogen Gas)

  • 송창호;박동화;신백균
    • 조명전기설비학회논문지
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    • 제25권4호
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    • pp.65-70
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    • 2011
  • Perfluorocompounds (PFCs) gases were decomposed by gliding arc plasma generated by AC pulse power. $N_2$ gas of 10 LPM flow rate and $H_2$ gas of 0.5 LPM were introduced into the gliding arc plasma generated between a pair of electrodes with SUS 303 material, and the PFCs gases were injected in the plasma and thereby were decomposed. The PFCs gas-decomposition-characteristics through the gliding arc plasma were analyzed by FT-IR, where pure $N_2$ and $H_2$-added $N_2$ environment were used to generate the gliding arc plasma. The PFCs gas-decomposition-properties were changed by electric power for gliding arc plasma generation and the H2 gas addition was effective to enhance the PFCs decomposition rate.

ULSI 확산억제막으로 적합한 Ti-Si-N의 조성 범위에 관한 연구 (A study of Compositional range of Ti-Si-N films for the ULSI diffusion barrier layer)

  • 박상기;강봉주;양희정;이원희;이은구;김희재;이재갑
    • 한국진공학회지
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    • 제10권3호
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    • pp.321-327
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    • 2001
  • Radio frequency magnetron sputtering방법으로 타켈의 Ti/si 조성과 $N_2$ 유량을 변화시켜 증착한 다양한 조성비의 Ti-Si-N 박막의 비저항 변화와 확산방지능력을 조사하였다. 높은 Si 함량을 포함한 Ti-Si-N박막내의 Si은 주로 비정질의 $Si_3N_4$ 형태로 존재하였으며 $N_2$의 양이 증가함에 따라 비저항도 증가하였다. 반면, 낮은 Si 함량을 포함한 Ti-Si-N박막은 낮은 $N_2$ 유량에서도 결정질의 TiN이 형성되었고 낮은 비저항을 나타내었다. 또한, 박막내의 N의 양이 증가함에 따라, 높은 박막의 밀도와 압축응력을 갖는 Ti-Si-N이 형성되었으며, 이는 박막 내의 N의 함량이 확산방지능력에 영향을 미치는 가장 중요한 요소 중 하나로 판단된다. 결과적으로, 29~49 at.%, Ti, 6~20 at.% Si, 45~55 at.% N 범위의 조성을 갖는 Ti-Si-N박막이 우수한 확산 억제 능력을 보유하면서 또한 낮은 비저항 특성을 나타내는데 적합한 조성 범위로 나타났다.

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