• Korean Chemical Engineering Research
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• 제48권2호
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• pp.185-192
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• 2010

매체 순환식 연소는 연소 공정 자체에서 질소 산화물 생성이나 부가적인 에너지 소비 없이 이산화탄소 분리가 이루어지는 신공정이다. 이 공정은 금속 산화물 입자가 두 개의 반응기를 순환하며 산화와 환원을 거치는 과정으로 구성되어 있다. 이 연구에서는 bentonite에 담지된 산화철 산소 공여 입자의 반응 속도 식을 shrinking core 모델을 통하여 수립하였다. 반응성 결과를 바탕으로 반응기 설계 기준인 고체 순환량과 입자 충전량을 도출하였다. 매체 순환식 연소 공정의 적용을 위하여 두 가지 형태의 연결된 유동층 즉, 상승관과 기포 유동층이 각각 한 개씩인 형태, 상승관 한 개와 기포 유동층이 두 개로 구성된 형태로 시스템을 설계하였다. 고체 순환량은 loop-seal을 통하여 $30kg/m^2s$ 정도까지 변화시켰다. 고체 순환량은 loop-seal의 기체 주입량이 증가할수록 증가하였으며 보조 기체를 주입하면 그 양이 더 증대되었다. 고체 순환량이 증가함에 따라 상승관 내부의 고체량은 증가하였다. 상승관으로부터 다른 반응기로의 기체 누출량은 1% 미만의 수준이었다.

• 한국실내디자인학회논문집
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• 제21권5호
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• pp.355-362
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• 2012

Water Culture Pavilion was constructed as a part of dam construction and Four-major rivers restoration projects, which have the purpose to prevent damage of natural disaster, localized heavy rain and drought, and has several functions; promotion, education and region culture community. Exhibition space in this culture pavilion should have the excellent connection of various media, contents, and exhibition space because of limited space. The purpose of this study is to analyze flows, continuation and connection of exhibit space with the perspectives of the attribute of water and to suggest various content things, technical, spatial types. This study targets Four-major rivers Water Culture Pavilion in Korea and suggests exhibition presentation methods as analyzing contents, media and constituent of exhibition space for each pavilion exhibition. The result of this study is as follows : First, the circulation is common expressed attribute of water in these four water culture pavilion. The reason is that there is a connection between Four-major rivers restoration projects and the physical attribute of water circulating the steps of evaporation, condensation and precipitation. Second, each pavilion presents circulative solid exhibit, circulative background exhibit, circulative reflective exhibit based on circulation. These three types of exhibition is related the floor separation. Third, each pavilion exhibit zone shows the most circulation, solid, background, reflexibility through educational contents and promoting contents by using graphic, video, sound media.

• Ocean Science Journal
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• 제40권4호
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• pp.201-208
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• 2005

An accurate particle tracking method for a finite difference method model is developed using a constant acceleration method. Being assumed constant temporal and spatial gradients, the new method permits temporal-spatial variability of particle velocity. Test results in a solid rotating flow show that the new method has second-order accuracy. The performance of the new method is compared with that of other methods; the first-order Euler forward method, and the second-order Euler predictor-corrector method. The new method is the most efficient method among the three. It is more accurate and efficient than the other two.

• 동력기계공학회지
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• 제16권4호
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• pp.24-29
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• 2012

The numerical analysis by using CFX 11.0 commercial code was done for prediction of fluid flow and thermal field in the vertical heat exchanger. The present experimental studies were also conducted to investigate the effects of circulating solid particles on the fluid flow and temperatures in the fluidized bed vertical shell and tube type heat exchanger with counterflow, at which the solid particles of glasses (3 $mm{\Phi}$) were used in the fluidized bed with a smooth tube. The effect of circulation on the distance(L) of tube inlet and baffle plate was also examined. The present experimental and numerical results showed that the particles in the distance (Ds) of 15 mm showed a more efficient circulation without stacked the space and the LMTD(Log Mean Temperature Difference) in the fluidized bed type was much lower than that in the typical type shell and tube heat exchanger.

• 한국수소및신에너지학회논문집
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• 제24권5호
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• pp.428-436
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• 2013

Attrition characteristics of $CO_2$ absorbents for pre-combustion $CO_2$ capture were investigated to check attrition loss of those absorbents and to determine solid circulation direction and the better $CO_2$ absorbent. The cumulative attrition losses of two absorbents increased with increasing time. However, attrition loss under a humidified condition was lower than that under a non-humidified condition case. Between two absorbents, attrition loss of PKM1-SU absorbent was higher than that of P4-600 absorbent. The average particle sizes of the attrited particles were less than $2.5{\mu}m$ for two absorbents under a non-humidified condition case, and therefore, we could conclude that the main mechanism of attrition for two absorbents is not fragmentation but abrasion. Based on the results from the test for the effect of humidity on the attrition loss, we selected solid circulation direction from SEWGS reactor to regeneration reactor because the SEWGS reactor contains more water vapor than regeneration reactor. Attrition loss and make-up rate of two absorbents were compared based on the results from $CO_2$ sorption capacity tests and attrition tests. Required make-up rate of P4-600 absorbent was lower than that of PKM1-SU absorbent. However, more detail investigation on the optimum regeneration temperature, manufacturing cost, solid circulation rate, regeneration rate, and long-term sorption capacity should be considered to select the best $CO_2$ absorbent.

• 한국수소및신에너지학회논문집
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• 제30권4호
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• pp.330-337
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• 2019

Effects of cyclone and freeboard geometry on solid entrainment loss were investigated with two different types of cyclones and bubbling beds in a gas-solid fluidized bed system. The solid entrainment loss was measured by collected fines during continuous solid circulation condition. Bubbling bed which has an expanded freeboard showed less solid entrainment than the bubbling bed which has a straight freeboard. The cyclone which has a wide gas-solid mixture inlet showed less solid entrainment loss than the cyclone which has a narrow gas-solid mixture inlet. Moreover, the cyclone has a wide gas-solid mixture inlet can capture smaller particles.

• 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.

• 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.

• Ocean and Polar Research
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• 제22권2호
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• pp.81-90
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• 2000

Supposed construction of a large port in the mouth of Tuman River requires careful examination of possible unfavorable ecological consequences for the Far Eastern Federal Marine Reserve. Since the Tuman River is the largest source of suspended material and possible contaminants flowing into the sea, and in order to understand how this material is allocated in the coastal zone, analyses are needed to check possible pathways of water transport and circulation system in the region. Linearized shallow water equations were used for numerical simulation of the wind-driven circulation to the north off the Tuman River mouth. The model results satisfactorily agreed with in situ data. The model circulation patterns are largely dependent on the wind direction and are conformed by the distribution of bottom sediments, and by the location of organic carbon and some pollutants accumulation zones. The most unfavorable situation for the Marine Reserve is the case of the southwesterly wind; even with quite moderate wind, the waters polluted by the run-off from the Tuman River can attain the south section of the Marine Reserve during the diurnal period.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.1199-1204
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• 2006

The pressure drop and heat transfer coefficient were measured at room temperature in CFB heat exchanger with multiple vertical tubes. Also the circulation rate of solid particles was measured. The theoretical model for predicting heat transfer coefficient using the solid flowrate was developed in this study. The model predictions were compared with the measured heat transfer coefficient to show relatively good agreement.