• 한국연소학회지
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• 제7권4호
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• pp.10-20
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• 2002

This paper discusses effect of solid mass inventory on the hydrodynamic characteristics of circulating fluidized bed(CFB). Operating parameters of solid mass inventory and air flow rates were varied to understand their effects on fludization pattern. Experimental measurements were made in a CFB of which height and diameter are 3m and 0.05m respectively. Black SiC particles ranging from $100{\mu}m\;to\;500{\mu}m$ were employed as the bed material. Superficial gas velocity of riser and J-valve fluidizing velocity were in the ranges of $1.39{\sim}3.24m/s\;and\;0.139{\sim}0.232m/s$, respectively. The axial solid fraction and solid circulation rate of CFB were calculated based on the experimental data and compared with modellings through IEA-CFBC Model and commercial CFD code.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2001년도 학술발표회 발표논문집
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• pp.275-280
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• 2001

The purpose of this study was to investigate the air flow characteristics of the rock bed storage for solar-heated greenhouse design. Heat storage material was gravels and experiments were performed under constant inside temperature condition. The experimental parameters were operation method and air flow rate of fan. It was resulted that the temperature and amount of heat stored in rock-bed increased as the increase of air flow velocity and were more influenced by operation of inlet fan than outlet fan.

• 한국수소및신에너지학회논문집
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• 제26권3호
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• pp.260-270
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• 2015

One-dimensional packed bed reactor model accounting for interfacial and intra-particle gradients was developed and based on it numerical analyses were performed to investigate the dynamic behavior of a commercial scale methanation reactor. Methanation reaction was almost complete near the reactor inlet and gases with equilibrated composition were discharged from the reactor. Both the intra-particle temperature gradient and differential surface temperature rise were found to be severe near the reactor inlet. To reduce the possible degradation or fracture of catalyst particles and prevent local overheating on the catalyst, addition of inert material can be an effective way.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제25회 KOSCI SYMPOSIUM 논문집
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• pp.165-172
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• 2002

This paper discusses hydrodynamic characteristics of cold circulating fluidized bed(CFB) in different solid mass inventories. Operating parameters of solid mass inventory, primary air and J-valve fluidizing air were varied to find out the effect on the flow fludization pattern. Experimental measurements were made in a 3m tall CFB that has 0.05m riser diameter and black silica-carbonate of particle sizes from $100{\mu}m$ to $500{\mu}m$ were employed as the bed material. The operating conditions of superficial gas velocity and J-valve fluidizing velocity were in the ranges of 1.39~3.24 m/s and 0.139~0.232 m/s respectively. The axial solid fraction and solid circulation rate of CFB were observed and compared with modelling through IEA-CFBC Model and commercial CFD code.

• Water Engineering Research
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• 제1권4호
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• pp.259-266
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• 2000

Scour hole is formed due to the high shear stress of the jet flow at the outlet of a hydraulic structure and vortex erosion occurs in the scour hole. It is important to determine the amount of vortex erosion occurs in the scour hole. It is important to determine the amount of vortex erosion for the design of bed protection. If the vortex erosion continues and reaches to the hydraulic structure, it causes the deformation of the structure itself. To obtain the amount of the vortex erosion, it is necessary to determine the shear velocity of the line vortex in the scour hole was derived by the theory of energy conservation and found to be related to the upstream overflow velocity. The amount of vortex erosion from the scour hole was obtained using entrainment equation for given value of shear velocity. For a design purpose, if the flow velocity at the end of an apron and the properties of bed material are given, the amount of vortex erosion was obtained.

• Environmental Engineering Research
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• 제9권5호
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• pp.193-200
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• 2004

A study of the treatment of piggery wastes using a multilayered metal-activated carbon system followed by carbon bed filtration was carried out at bench scale. From the physicochemical properties obtained from samples treated with aqueous solutions containing metallic ions such as Ag$^+$, Cu$^{2+}$, Na$^{-}$, K$^+$ and Mn$^{2+}$, main inspections are subjected to isothem shape, pore distribution with micropore, SEM and EDX. Multilayered metal-activated carbons were contacted to waste water to inwestigate the simultaneous catalytic effect for the COD, BOD, T-N and T-P removal. From these removal performance was achieved. The high efficiency of the multilayered metal-activated carbon bed, satisfactory removal performance was achieved. The high efficiency of the multilayered metal-activated carbon bed was derermined by the properties of this material for trapping, catalytic effect and adsorption of organic solid particles.

• 한국식품과학회지
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• 제34권5호
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• pp.924-926
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• 2002

분쇄땅콩의 결착력 증대 및 산패방지를 위한 유동층코팅 기술을 개발하고자, 유동충코팅공정의 흡입공기온도 및 분무압력이 분쇄땅콩의 유동층 코팅효율에 미치는 영향을 검토하였다. 흡입공기온도가 높을수록 코팅효율이 증가하였으며, 분무압력도 3 bar까지는 분무압력이 커질수록 코팅효율이 증가하는 경향을 나타내었다. 그리고, 덱스트린과 카제인나트륨로 구성된 코팅물질은 분쇄땅콩의 산패를 부분적으로 억제할 수 있음을 보여주었다.

• 한국환경과학회지
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• 제16권3호
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• pp.255-260
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• 2007

The photocatalytic decolorization of Rhodamine B (RhB) was studied using packed-bed reactor and immobilized $TiO_2/UV$ System. The 20 W UV-A, UV-B and UV-C lamps were employed as the light source. The effect of shape and surface polishing extent of reflector, distance between the reactor and reflector, reactor material were investigated. The results showed that the order of the initial reaction constant with reflector shape was round > polygon > W > rhombus. The optimum distance between the reactor and reflector was 2 cm. The initial reaction constant of quartz reactor was 1.46 times higher than that of tile PVDF reactor.

• 소성∙가공
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• 제31권2호
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• pp.89-95
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• 2022

3D printing products manufactured by material extrusion are used in many industrial fields recently. However, these products are difficult to use in the field due to their low tensile strengths. In order to solve this problem, research on improving the tensile strength of the output using a 3D printer has been continuously conducted. In this study, we performed a tensile test using Universal Testing Machine according to infill pattern, nozzle temperature, bed temperature, and printing speed conditions. Results revealed that tensile specimen of concentric shape had the highest tensile strength in infill pattern condition and that the tensile strength increased linearly with increasing nozzle and bed temperatures. However, the tensile strength decreased with increasing printing speed. Consequently, we confirmed that tensile strength could be increased and decreased depending on output conditions of 3D printing.

• 대한토목학회논문집
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• 제32권1B호
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• pp.1-7
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• 2012

본 연구에서는 준 2차원 수치모형인 GSTARS를 이용하여 형산강의 하상변동모의에 적합한 최적 유사량공식을 산정하고자 하였다. 모형의 검보정을 위한 유사량, 하상재료 및 하천지형자료를 현장조사를 통해 취득하였다. 현재까지 널리 적용되는 유사량 공식들에 대하여 장기하상변동 모의결과의 실측치에 대한 평균오차, 상대오차, 평균제곱오차, 상대제곱근오차, 불일치율, 그리고 Nash-Sutcliffe 효율계수를 비교한 결과, Laursen(1958)공식이 형산강의 장기하상 변동을 모의하기 위한 가장 적합한 유사량공식으로 판단되었다.