• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.5
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• pp.247-253
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• 2003

In this study, a numerical analysis of the deposition of gallium arsenide from TMGa and arsine in a horizontal MOCVD reactor is performed to investigate the effect of inlet diffuser shape of reactor on the flow and deposition characteristics. The effects of two geometric parameters (diffuser angle, diffuser shape) on the growth rate, growth rate uniformity, flow uniformity and pressure loss are presented. As a results, it is found that the optimum linear diffuser angle is in the range of $50^{\circ}$∼$55^{\circ}$ and parabolic diffuser in the range of $40^{\circ}$∼$45^{\circ}$ from the viewpoint of growth rate uniformity, flow uniformity and average growth rate. It is also found that variation of diffuser angle has greater impact on growth rate uniformity than average growth rate particularly in parabolic diffuser.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.2
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• pp.92-98
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• 2015

The physical effect induced by acoustic cavitation was investigated to accumulate basic data for the design of ultrasonic soil washing processes using aluminum foil erosion tests. A square aluminum foil was placed on the glass beads in the pyrex vessel submerged in the sonoreactor equipped with a 36 kHz ultrasound transducer module at the bottom. Cavitational erosion of foils was quantitatively analyzed for various glass bead diameter conditions (1, 2, and 4 mm), glass bead height conditions (5, 10, 15, and 20 mm), and water height conditions (5, 10, 15, and 20 mm). It was found that aluminum foil erosion significantly increased as the glass bead diameter increased and water height over the glass bead increased due to less attenuation of ultrasound and the optimization of sound field for cavitation. Moreover mechanical mixing was suggested to move constantly particles to the bottom area where the acoustic cavitation occurs most violently. It was because aluminium foil erosion by ultrasound transmitted through glass beads was relatively too weak.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.1
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• pp.21-26
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• 2002

The behavior of the biological water treatment process on start-up operation was evaluated in the integrated recirculating aquaculture system consisting of a double drain type rearing tank ($2.5 m^3$), a sedimentation tank, a floating bead filter, a foam separator and a rotating biological contactor. A system was stocked with nile tilapia (Oreochromis niloticus) at an initial rearing density of $2\%$ for 2 weeks for acclimated rotating biological contactor. The total ammonia nitrogen (TAN) level increased to $13.6 g/m^3$ on day 4 after adding feed and was decreased to $0.3 g/m^3$ on day 7. The total suspended solid was completely removed during overall experimental period.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.118-119
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• 2007

TWO-CHANNEL방식의 디지털 광센서는 I2C의 출력을 가지고 있다. 하나의 CMOS집적회로에 포토다이오드와 기존의 아날로그-디지털 변환기(ADC)로 구성되어 있었던 방식과는 달리 2개의 비교기(Comparotor)로 2개의 채널을 형성하게 된다. 인간의 눈과 비슷한 반응을 얻기 위해 16-bit의 유효 범위를 갖는다. 이 광센서는 광원의 넓은 파장에 적합하게 설계 되었다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.11a
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• pp.417-418
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• 2002

열분해는 독성이 강한 염화탄화수소의 처리뿐만 아니라 염화물을 효과적으로 제거하여 이들로부터 유용한 탄화수소를 얻을 수 있는 반응이다 Biomass에 열분해를 적용하여 가스상, 액상, 고상형태의 유동한 부산물로 전환시키고 있으며 현재 액상생성물은 외국에서 큰 주목을 받고 있는 부산물이다. 1,1,2-trichloroethane(TCE)는 독성이 강한 휘발성 유기화합물(VOC)이며 발암물질이다. (중략)

• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.482-488
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• 1997

Copper recovery from waste water of electronic industry has been conducted effectively in a fluidized bed reactor. Initial concentration of copper in the waste water, liquid flow rate in the reactor, reaction temperature and time and current density between the cathode and anode in the reactor have been selected as operating variables. The effects of operating variables on the recovery of copper have been studied. It has found that the copper resolved in the waste water can be recovered continuously by means of a fluidized bed reactor The recovery of copper decreased with an increase in the initial concentration of copper in the waste water, while it increased with increasing reaction time and current density, however, it exhibited its maximum value with the variations of liquid flow rate and reaction temperature. The optimum reaction condition to maintain the copper recovery around 85% is as follows ; $X_o=3wt%$, $U_L=0.5cm/s$, $T=25^{\circ}C$, $I=7A/dm^2$ and t=2hrs within this experimental condition.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.2
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• pp.155-162
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• 2003

Design optimization of a transonic compressor rotor (NASA rotor 37) using response surface method and three-dimensional Navier-Stokes analysis has been carried out in this work. Baldwin-Lomax turbulence model was used in the flow analysis. Three design variables were selected to optimize the stacking line of the blade. Data points for response evaluations were selected by D-optimal design, and linear programming method was used for the optimization on the response surface. As a main result of the optimization, adiabatic efficiency was successfully improved. It is also found that the design process provides reliable design of a turbomachinery blade with reasonable computing time.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.135-142
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• 2001

Design optimization of a transonic compressor rotor (NASA rotor 37) using response surface method and three-dimensional Navier-Stokes analysis has been carried out in this work. Baldwin-Lomax turbulence model was used in the flow analysis. Three design variables were selected to optimize the stacking line of the blade. Data points for response evaluations were selected by D-optimal design, and linear programming method was used for the optimization on the response surface. As a main result of the optimization, adiabatic efficiency was successfully improved. Ana, it is found that the design process provides reliable design of a turbomachinery blade with reasonable computing time.

• The KSFM Journal of Fluid Machinery
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• v.19 no.2
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• pp.16-20
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• 2016

Design optimization of a transonic compressor rotor(NASA rotor 37) was carried out using response surface method(RSM) which is one of the optimization methods. A numerical simulation was conducted using ANSYS CFX by solving three-dimensional Reynolds-averaged Navier Stokes(RANS) equations. Response surfaces that were based on the results of the design of experiment(DOE) techniques were used to find an optimal shape of blade which has the maximum aerodynamic performance. Two objective functions, viz., the adiabatic efficiency and the loss coefficient were selected with three design configurations to optimize the blade shape. As a result, the efficiency of the optimized blade is found to be increased.

• Korean Chemical Engineering Research
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• v.45 no.6
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• pp.656-662
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• 2007

Fuel reformer using plasma and shift reactor for CO oxidation were designed and manufactured as $H_2$ supply device to operate a polymer electrolyte membrane fuel cell (PEMFC). $H_2$ selectivity was increased by non-thermal plasma reformer using GlidArc discharge with Ni catalyst simultaneously. Shift reactor was consisted of steam generator, low temperature shifter, high temperature shifter and preferential oxidation reactor. Parametric screening studies of fuel reformer were conducted, in which there were the variations of the catalyst temperature, gas component ratio, total gas ratio and input power. and parametric screening studies of shift reactor were conducted, in which there were the variations of the air flow rate, stema flow rate and temperature. When the $O_2/C$ ratio was 0.64, total gas flow rate was 14.2 l/min, catalytic reactor temperature was $672^{\circ}C$ and input power 1.1 kJ/L, the production of $H_2$ was maximized 41.1%. And $CH_4$ conversion rate, $H_2$ yield and reformer energy density were 88.7%, 54% and 35.2% respectively. When the $O_2/C$ ratio was 0.3 in the PrOx reactor, steam flow ratio was 2.8 in the HTS, and temperature were 475, 314, 260, $235^{\circ}C$ in the HTS, LTS, PrOx, the conversion of CO was optimized conditions of shift reactor using simulated reformate gas. Preheat time of the reactor using plasma was 30 min, component of reformed gas from shift reactor were $H_2$ 38%, CO<10 ppm, $N_2$ 36%, $CO_2$ 21% and $CH_4$ 4%.