• 한국산학기술학회논문지
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• 제17권1호
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• pp.290-297
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• 2016

도시철도 터널내에 축적된 미세먼지(PM10 and PM2.5)의 제거를 위해 사용되는 분진흡입차량의 성능은 하부흡입시스템의 설계방법에 따라 성능이 달라진다. 본 논문에서는 터널집진차량의 하부에 설치된 먼지흡입시스템의 고효율화를 위하여 궤도의 바닥면에 쌓인 먼지를 비산시키는 압축공기 블로어와 먼지 흡입구를 동시에 가지는 모듈화된 먼지흡입구조를 제안하였다. 흡입과 블로어의 상반된 구조를 동시에 가진 흡입시스템의 먼지유동 최적화를 위해 난류유동에 기초한 수치해석을 수행하였다. 해석결과로 먼지흡입효율을 최대화 할 수 있는 공기 블로어의 설치각이 $6^{\circ}$ 내외에서 결정되고, 이를 적용하면 5 km/h의 청소속도를 가지는 분진흡입차량의 흡입효율을 10%이상 높일 수 있음을 확인하였다.

• 대한기계학회논문집
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• 제15권1호
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• pp.285-291
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• 1991

본 연구에서는 800 1pm인 대유량을 처리하고 공기중 1.8~4.5$\mu\textrm{m}$ 입자를 효율 적으로 선별하여 농축시키는 슬릿형 2단 가상충돌기를 설계 제작하고 그 성능이 평가 되었다. 즉, 첫째단과 둘째단에서 4.5$\mu\textrm{m}$과 1.8$\mu\textrm{m}$이 각각 50%의 효율로 분리되도록 설계되었다. 즉, 첫째단과 둘째단에서 4.5$\mu\textrm{m}$과 1.8$\mu\textrm{m}$이 각각 50%의 효율로 분리되도 록 설계한다. 설계인자(design parameter)들을 결정하기 위하여 먼저 슬릿형 노즐의 1단 가상충돌기의 분리효율(separation efficiency)에 대한 실험을 통하여 50% 커트오 프 Stokes수를 구하고, 이를 기초로 하여 2단 가상 충돌기의 주요치수와 작동조건을 결정하였다.

• 청정기술
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• 제20권3호
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• pp.283-289
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• 2014

가정용 진공청소기는 기본적으로 집진장치(dust collector), 프리 필터(pre filter), 모터(motor), 배기 필터(exhaust filter)의 구조를 가지며, 흡입된 먼지가 포함된 공기는 이러한 구조를 지나 깨끗한 공기가 되어 대기로 방출된다. 본 연구에서는 실생활에 사용되고 있는 구조가 다른 2개의 사이클론 청소기를 선정하여 사이클론 청소기 내 집진장치의 내부 공기 유동에 대해 전산유체역학을 적용하여 집진성능을 평가하고자 하였다. 사이클론 콘(cyclone cone) 영역에서 공기의 유선(streamline)을 해석한 결과, 사이클론 콘 영역에서 상당한 선회수를 가지는 것을 확인하였다. 특정 형상의 청소기에 대한 전산해석 결과에서 출구에서의 속도 분포가 매우 불균일한 결과를 나타내었고 이로 인해 집진성능에 악영향이 나타남이 파악되었다. 이 문제를 해결하기 위해 집진장치 형상에 추가적으로 배플을 설치하여, 달라진 속도 분포에 의한 속도 RMS (Root Mean Square) 값의 개선을 평가하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2007-2009
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• 1999

In this paper, discharge domain of wire-cylindrical plasma reactor was separated from a gas flow duct to avoid unstable discharge by aerosol particle deposited on discharge electrode and grounded electrode. The NOx, SOx removal was experimentally investigated by a reaction induced to ammonium nitrate, ammonium sulfate using a low price of aqueous NaOH solution and a small quantity of ammonia. Volume percentage of aqueous NaOH solution used was 20% and $N_2$ flow rate was 2.5[$\ell$/min] for bubbling aqueous NaOH solution. Ammonia gas(14.82%) balanced by argon was diluted by air and was introduced to a main simulated flue gas duct through $NH_3$ injection system which was in downstream of reactor. The $NH_3$ molecular ratio[MR] was determined based on $NH_3$ to [NO+$SO_2$]. MR is 1.5. The NOx removal rates increased in the order of DC, AC and pulse, but SOx removal rates was not significantly effected by source of electricity. The NOx removal rate slightly decreased with increasing initial concentration but SOx removal rate was not significantly effect by initial concentration, and NOx, SOx removal rates decreased with increasing gas flow rate.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.604-605
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• 2017

본 연구는 C-D 노즐로부터 발생하는 초음속 제트 유동을 가시화하는데 목표가 있다. 본 실험에서 PIV를 이용하여 정량적인 제트의 결과를 얻어 쉴리렌 기법을 통해 얻은 정성적 결과와 비교하여 나타내었다. 컬러 쉴리렌은 $0.5{\mu}s$의 스파크 광원을 이용하였다. $M_d=2.0,2.2$의 C-D 노즐에 대해 다양한 압력비($p_0/p_b=5$, 6, 7, 8)를 적용하여 발생하는 제트에 대해 가시화 실험을 수행하였다. 가시화 결과, 제트의 주된 특성인 과팽창 제트, 부족팽창 제트, 음파 등이 관측 되었다.

• Nuclear Engineering and Technology
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• 제52권10호
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• pp.2230-2237
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• 2020

Self-priming venturi scrubber is one of the most effective devices used to collect aerosols and soluble gas pollutants from gaseous stream during severe accident in a nuclear power plant. The present study focuses on investigation of dust particle removal efficiency of the venturi scrubber both experimentally and theoretically. Venturi scrubber captures the dust particles in tiny water droplets flowing into it. Inertial impaction is the main mechanism of particles collection in venturi scrubber. The water injected into venturi throat is in the form of jets through multiple holes present at venturi throat. In this study, aerosols removal efficiency of self-priming venturi scrubber was experimentally measured for different operating conditions. Alumina (Al₂O₃) particles with 0.4-㎛ diameter and 3950 kg/㎥ density were treated as aerosols. Removal efficiency was calculated for different gas flow rates i.e. 3-6 ㎥/h and liquid flow rates i.e. 0.009-0.025 ㎥/h. Experimental results depict that aerosols removal efficiency increases with the increase in throat velocity and liquid head. While at lower air flow rate of 3 ㎥/h, removal efficiency decreases with the increase in liquid head. A theoretical model of venturi scrubber was also employed and experimental results were compared with mathematical model. Experimental results are found to be in good agreement with theoretical results.

• 한국소음진동공학회논문집
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• 제14권6호
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• pp.528-535
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• 2004

Ultrasonic Vibrator is designed to achieve the maximum vibration amplitude at 30 kHz by in-cluding a horn (diameter, 40 mm), mechanical vibration amplifier at the top of the ultrasonic vibrator in the system and making the complete system resonate. In addition, it is experimentally visualized by particle imaging velocimetry (PIV) that the acoustic streaming velocity in the gap is at maximum when the gap between the ultrasonic vibrator and stationary plate agrees with the multiples of half-wavelength of the ultrasonic wave. This fact results from the resonance of the sound wave and the theoretical analysis of that is also accomplished and verified by experiment. It is observed that the magnitude of the acoustic streaming dependent upon the gap between the ultrasonic vibrator and stationary plate possibly changes due to the measurement of the average velocity fields of the acoustic streaming induced by the ultrasonic vibration at resonance and non-resonance. There exists extremely small average velocity at non-resonant gaps while the relatively large average velocity exists at resonant gaps compared with non-resonant gaps. It also reveals that there should be larger axial turbulent intensity at the hub region of the vibrator and at the edge of it in the resonant gap where the air streaming velocity is maximized and the flow phenomena is conspicuous than that at the other region. Because the variation of the acoustic streaming velocity at resonant gap is more distinctive than that at non-resonant gap, shear stress increases more in the resonant gap and is also maximized at the center region of the vibrator except the local position of center (r〓0). At the non-resonant gap there should be low values of vorticity distribution, but in contrast to the non-resonant gap, high and negative values of it exist at the center region of the vibrator with respect to the radial direction and in the vicinity of the middle region with respect to the axial direction. Acoustic streaming is noise-free due to the ultrasonic vibration and maintenance-free because of the absence of moving parts. Moreover, the proposed method by acoustic streaming can be utilized to the nano and micro-electro mechanical systems as a driving mechanism in addition to the augmentation of the streaming velocity.

• Applied Science and Convergence Technology
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• 제24권5호
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• pp.196-202
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• 2015

Human blood consists of 55% of plasma and 45% of blood cells such as white blood cell (WBC) and red blood cell (RBC). In plasma, there are many kinds of promising biomarkers, which can be used for the diagnosis of various diseases and biological analysis. For diagnostic tools such as a lab-on-a-chip (LOC), blood plasma separation is a fundamental step for accomplishing a high performance in the detection of a disease. Highly efficient separators can increase the sensitivity and selectivity of biosensors and reduce diagnostic time. In order to achieve a higher yield in blood plasma separation, we propose a novel fluid wing structure that is optimized by COMSOL simulations by varying the fluidic channel width and the angle of the bifurcation. The fluid wing structure is inspired by the inertial particle separator system in helicopters where sand particles are prevented from following the air flow to an engine. The structure is ameliorated in order to satisfy biological and fluidic requirements at the micro scale to achieve high plasma yield and separation efficiency. In this study, we fabricated the fluid wing structure for the efficient microfluidic blood plasma separation. The high plasma yield of 67% is achieved with a channel width of $20{\mu}m$ in the fabricated fluidic chip and the result was not affected by the angle of the bifurcation.

• 한국안전학회지
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• 제28권6호
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• pp.11-16
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• 2013

This paper presents a study on the analyzing reliability of smoke fire detector using accelerated life test. In general, the smoke fire detector is broken by dust which flow in smoke detection chamber. In order to conduct accelerated life test of smoke fire detector dust is set accelerated factor in this paper. The dust is fly-ash which is test particle 5th regulated by KS A 0090. The dust accelerated level is 60 g, 180 g and 360 g and failure time is measured by smoke sensitivity testing. It is considered to failure of detector if detector don't operate within 30 secconds when subjected to an air stream having a velocity of 20 cm/s~40 cm/s containing smoke with a concentration of 15% of rate of light-response of 1 m. The goodness of fit test and mean life prediction conduct using the failure time. The result show that life distribution fits the weibull distribution for failure time data and the mean lifes calculate 22.5 year in domestic product and 14.7 years in overseas product applied dust stress only.

• 한국결정성장학회지
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• 제9권1호
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• pp.119-125
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• 1999

본 연구는 싸이클론 반응로에서 $FeS_{2}$의 반응 특성에 관한 조사를 연구하였다. 수학적인 모형도로 이 반응로에서 $FeS_{2}$의 oxidation과 suifation 등을 전개하엿다. 모형은 $FeS_{2}$에서 chemical control shrinking core로서 그리고 ${Ca(OH)}_{2}$에서 fluid film control shrinking core로서 가정하였으며 수식으로서 발전시켰다. 본 실험은 이 반응 파라메터들의 영향에 연구로서 진행하였으며 즉 반응로의 온도변화, $FeS_{2}$의 입자크기, 공기 주입비율, 시료 주입비율, 그리고 $FeS_{2}$와 ${Ca(OH)}_{2}$ 비율 등이다. Oxidation과 Sulfation에 의한 반응물들은 화학적 및 물리적으로 특성을 기술하였다.