• 한국분무공학회지
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• 제4권3호
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• pp.32-41
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• 1999

In this research, internal-mixing twin-fluid atomizer using sonic energy is designed and manufactured. We are trying to intimate high efficiency twin-fluid atomizer to obtain good liquid atomization in the low pressure region. Define of geometric form of atomizer, characteristics of spray is influenced by position, depth and height variation of cavity resonator, variation of sound intensity and resonant sound frequency with liquid flow rate. The liquid atomization is promoted by multi-stage disintegration of mixing flow of gas with liquid and the optimum condition of position and depth of cavity resonator according to sonic energy is obtained from the condition at a=2.5mm and L=2mm. The velocity distribution of droplets shows negative value due to recirculation region at the center of axial, and as the radial direction distance is far, the velocity distribution of droplets decrease slowly after having a maximum value. However velocity and SMD show nearly uniform distribution at the down stream and as result compared to Nukiyama and Tanasawa's equation. atomization of mixing flow with air and liquid dispersing from the outlet of the nozzle is promoted by the effect of collision at the cavity resonator.

• Korean Chemical Engineering Research
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• 제56권2호
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• pp.186-190
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• 2018

For the first time, the characteristics of solid circulation rate ($G_S$) were investigated in a three-phase (gas-liquid-solid) viscous circulating fluidized bed (TPCFB). The solid circulation rate was controlled separately by adjusting the experimental apparatus as well as operating variables. Effects of primary and secondary liquid velocities ($U_{L1}$ and $U_{L2}$), gas velocity ($U_G$), particle size ($d_p$), height of particles piled up in the solid recycle device (h), and viscosity of continuous liquid media (${\mu}_L$) on the value of $G_S$ were determined. The experimental results showed that the value of $G_S$ increased with increases in the values of $U_{L1}$, $U_{L2}$, h and ${\mu}_L$, while it decreased with increasing $U_G$ and $d_p$ in TPCFBs with viscous liquid media. The values of $G_S$ were well correlated in terms of dimensionless groups within this experimental conditions.

• Earthquakes and Structures
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• 제27권3호
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• pp.165-176
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• 2024

In this study, a direct Lagrangian-based three-dimensional computational procedure is developed to evaluate the seismic performance of reinforced concrete liquid-containing circular tanks (RC-LCT). In this approach, fluid-structure interaction (FSI), material nonlinearity, and liquid-structure large deformations are formulated realistically. Liquid is modeled using Mie-Grüneisen equation of state (EOS) in compressible form considering the convective and impulsive motions of fluid. The developed numerical framework is validated based on a previous study. Further, nonlinear analyses are carried out to assess the seismic performance of RC-LCT with various diameter-to-liquid height ratios ranging from 2.5 to 4.0. Based on observations, semi-deep tanks (i.e., D/H_l=2.5) show low collapse ductility due to their shear failure mode while shallow tanks (i.e., D/H_l=4.0) behave in a more ductile manner due to their dominant wall membrane action. Furthermore, the semi-deep tanks provide the least over-strength and ductility due to their catastrophic failure with little energy dissipation. This study shows that LCTs can be categorized as between immediately operational and life safety levels and therefore a drift limiting criterion is necessary to prevent probable damages during earthquakes.

• 대한환경공학회지
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• 제29권1호
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• pp.62-67
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• 2007

본 연구의 목적은 액상 균일질 촉매를 이용하여 연소가스 중에 포함되어 있는 $SO_2/NO$의 동시제거 기술 개발에 있다. 연구는 bench scale/소규모 pilot scale에서 이루어졌으며 연구 결과는 다음과 같다. 1) $SO_2$는 실험조건에 상관없이 높은 제거효율을 가지는 것으로 확인되었다. 그러나 NO의 경우 충진층 높이가 증가할수록, 농도가 낮을수록, 촉매 분사량이 증가할수록 제거효율이 증가하는 것으로 나타났다. 2) Fe(II)-EDTA를 이용한 $SO_2/NO$ 동시처리 기술 개발을 위한 최적의 설계 인자는 충진 높이 =0.5 m, 액체-기체비 = 20 $L/m^3$, 반응기 단수=3단, 반응기 단면적 = 0.025 $m^2$로 결정하였다. 3) 연구 결과를 기초로 $SO_2/NO$의 동시처리 효율을 실험한 결과 각각 95%, 81% 이상 제거가 가능했다. 4) 높은 HTU는 NO의 제거에 있어 유리하지만 과도한 HTU는 스크러버의 운전효율을 감소시키므로 최적의 HTU를 결정하는 것이 필요하다.

• 대한영양사협회학술지
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• 제20권1호
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• pp.63-69
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• 2014

The volume perception of water according to cup shape was examined in female college students divided into a normal weight group (<23 body mass index, n=51) and an overweight group (${\geq}$23 body mass index, n=48). The perceived water volume was recorded by participants after they observed the water volume in cups with different shape (highball and tumbler) and with different base height (high base and low base), which contained the same amount of water (150 ml). The normal weight group perceived a water volume of 238.5 ml (highball) and 201.6 ml (tumbler) for the high base cups. The overweight group perceived a volume of 245.6 ml (highball) and 188.8 ml (tumbler). For the low base cups, the normal weight group perceived a water volume of 207.8 ml (highball) and 104.1 ml (tumbler). The overweight group perceived a volume of 202.2 ml (highball) and 100.4 ml (tumbler). Both the normal weight and overweight groups perceived significantly more liquid in the highball cups compared to the tumbler cups. In addition, both groups perceived significantly more liquid in the high base cups compared to the low base cups. However, there were no significant differences in the estimated variance of perceived volume between the normal weight and overweight groups according to the cup shape and cup base height. In conclusion, cup shape and base height potentially affects volume perception. Therefore, modifying cup shape may be used in a weight control program to help control caloric beverage consumption.

• 대한기계학회논문집B
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• 제26권1호
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• pp.82-93
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• 2002

The effects of the interaction between the flow and temperature field and a boundary layer due to a variety of the height of a vortex generator are experimentally investigated. The test facility consists of a boundary-layer wind tunnel with the vortex generator protruding from the bottom surface. In order to control the strength of the longitudinal vortices, the angle of attack and the spacing distance of the vortex generator are 20 degree and 40 mm, respectively. The height of the vortex generator (H) is 15 mm, 20 mm and 30 mm and the cord length of it is 50 mm. Three-component mean velocity measurements are made using a 5-hole probe system and the surface temperature distribution is measured by the hue capturing method using thermochromatic liquid crystals. By using the method mentioned above, the following conclusions are obtained from the present experiment. The boundary layer is thinned in the downwash region where the strong downflow and the lateral outflow of the boundary layer fluid occur and thickened in the upwash re,3ion where the longitudinal vortex sweeps low momentum fluid away from the bottom surface. In case that the height of the vortex generator increases, the averaged circulation and the maximum vorticity of the vortex pair decrease. The contours of the non-dimensional temperature show the similar trends fur all the cases (H=15 mm, 20 mm and 30 mm). The peak augmentation of the distribution of the local non-dimensional temperature occurs in the downwash region near the point of minimum boundary-layer thickness.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.209-209
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• 2017

The application of liquid swine manure to soil has been commonly reported to increase crop productivity by improving plant nutrient availability. This study was conducted to investigate the effect of liquid swine manure (LSM) application on yield of green manure crops in paddy. Three different application rates of LSM equivalent to 25%, 50%, and 75% of standard fertilization rate of P were applied to the paddy field after rice harvest, and two cover crops, hairy vetch (Vicia villosa Roth) and barley (Hordeum vulgare L.), were subsequently mix-seeded and cultivated. Plant height of barley was 7% higher in LSM P25% and LSM P50% compared to control treatment (no LSM application), while no significant difference was observed between LSM P75% and control. However, there were no significant differences in plant height of hairy vetch among treatments. Dry matter (DM) yield of green manure increased with LSM application rate, reaching a maximum at LSM P50% (38 and 17% yield increase over control for hairy vetch and barley, respectively), but it decreased at LSM P75% rate. Nitrogen production by green manure crops was the highest in LSM P50% treatment, where the amount of produced N was 57% higher than the optimum N fertilization level for rice ($90kg\;N\;ha^{-1}$). Excess green manure biomass above an optimum level can be removed and utilized either for incorporation into nearby cropland or for sale as fresh forage. Therefore, it is concluded that the application rate of LSM P50% is recommendable for the maximum biomass and nitrogen production from green manure crops in paddy.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.399-413
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• 2020

The numerical simulation of liquid sloshing in the three-dimensional tanks under horizontal excitation and roll excitation was carried out, and the inhibition effect of different baffles on the sloshing phenomenon was investigated. The numerical calculations were carried out by the nonlinear Boundary Element Method (BEM) with Green's theorem based on the potential flow, which was conducted with the governing equation corresponding to the boundaries of each region. The validity of the method was verified by comparing with experimental values and published literatures. The horizontal baffle, the vertical baffle and the T-shaped baffle in the sloshing tanks were investigated respectively, and the baffles' position, dimension and the liquid depth were provided and discussed in detail. It is drawn that the baffle shape plays a non-negligible role in the tank sloshing. The vertical baffle is a more effective way to reduce the sloshing amplitude when the tank is under a horizontal harmonic excitation while the horizontal baffle is a more effective way when the tank is under a roll excitation. The amplitude of free surface elevation at right tank wall decreases with the increasing of the horizontal baffle length and the vertical baffle height. Although the T-shaped baffle has the best suppression effect on tank sloshing under horizontal excitation, it has limited suppression effect under roll excitation and will complicate the sloshing phenomenon when changing baffle height.

• 한국화재소방학회논문지
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• 제26권3호
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• pp.73-78
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• 2012

화점높이 변화에 따른 풀 화재와 회오리 화염의 연소특성을 알아보기 위하여 인화성 액체인 메탄올을 $100{\times}100{\times}50$ 크기의 스테인레스 재질의 사각형 용기에 넣고 연소실험을 하였다. 연소시간, 질량감소속도, 화염온도, 화염높이 및 외부로부터 화염으로의 공기유입속도 등을 측정하였으며, 연소시 화염의 거동은 비디오카메라를 이용하였다. 모든 실험결과로부터 화점높이 변화에 따른 연소특성은 풀 화재보다는 회오리 화염에 있어서 더 큰 영향을 준다는 것을 알 수 있었다.

• 한국산학기술학회논문지
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• 제11권11호
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• pp.4671-4676
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• 2010

화점높이 변화에 따른 풀 화재의 연소특성을 알아보기 위하여 인화성액체인 메탄올과 노르말 헵탄을 $100mm{\times}100mm{\times}50mm$ 크기의 사각형 용기에 내에 넣고 연소실험을 하였다. 용기의 재질은 스테인레스를 사용하였다. 연소시간, 질량감소속도, 화염온도, 화염높이 및 외부에서 화염으로의 공기유입속도 등을 측정하였으며 연소시 화염의 거동은 비디오카메라를 이용하여 촬영하였다. 실험을 통해서 화점의 높이가 증가할수록 외부에서 화염으로 유입되는 차가운 공기의 유입량이 증가하여 풀 화재의 연소특성이 감소함을 확인 할 수 있었다.