• New & Renewable Energy
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• v.2 no.2 s.6
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• pp.60-68
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• 2006

소수 station의 수소분리정제를 위한 compact형 PSA 공정을 연구하였다. 기존 PSA 공정의 흡착탑이 차지하는 시스템의 공간을 줄이기 위하여 하나의 흡착탑 안에 다른 흡착탑을 넣어 흡착탑이 차지하는 공간을 최소화하였으며, 흡착탑 간의 열교환이 효과적으로 일어나도록 설계하였다. 수소 혼합물에 대한 활성탄으로 충진된 dual bed에서의 수소 혼합물에 대한 흡/탈착 동특성 실험을 실시하였으며, 시간에 따른 농도와 온도의 변화를 측정하였다. 수소 혼합물로는 $H_2/CO/CH_4/CO_2$ (69:2:3:26 vol.%) 를 사용하였으며, 흡착유량은 7LPM, 흡착압력은 9atm 조건에서 운전하였다. Inner bed와 outer bed의 성능은 각각의 열전달 특성의 차이로 인하여 다르게 나타났으나, 단일탑의 동특성보다는 우수한 성능을 보이고 있었다. 따라서 개발된 dual bed는 적은 부지를 차지하면서도, 보다 우수한 수소 분리 성능을 보일 수 있는 PSA 공정에 응용될 수 있음을 확인하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.5-8
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• 2006

수소 station에서 수소분리정제를 위한 compact형 PSA 공정 설계를 위하여 활성탄으로 충진된 dual bed의 흡착동특성을 연구하였다. 기존 PSA 공정의 흡착탑이 차지하는 시스템의 공간을 줄이기 위하여 하나의 흡착탑 안에 다른 흡착탑을 넣어 흡착탑이 차지하는 공간을 최소화하고, 흡착탑 간의 열교환을 효과적으로 할 수 있도록 고안하였다. 수소 혼합물에 대한 dual bed에서의 흡착, 탈착 실험 실시하였으며, 시간에 따른 농도와 온도의 변화를 측정하였다. 수소 혼합물로는 $H_2/CO/CH_4/CO_2$ (69:2:3:26vol.%)를 사용하였으며, 흡착유량은 7LPM, 흡착압력은 9atm 조건에서 운전하였다. Inner bed와 outer bed의 수소 농도 파과곡선의 형태에 있어 차이를 보였으며, 이는 각 탑에서 열교환 효과로 인한 내부 온도 차이에 기인하여 발생하였다.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.82-87
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• 2008

$N_2O$ decomposition characteristics of dual bed mixed metal oxide catalytic system was investigated. The partial oxidation of methane at first reactor of dual bed catalytic system was performed over Co-Rh-Al (1/0.2/1) catalyst under the optimized condition of $8,000h^{-1}$ GHSV, gas ratio ($CH_4:O_2=5:1$) at $500^{\circ}C$. In the dual bed system investigated herein, the second catalyst bed was employed for the $N_2O$ decomposition using product of partial oxidation of methane at first bed. An excellent $N_2O$ conversion activity even at lower temperature ($<250^{\circ}C$) was obtained with Co-Rh-Al (1/0.2/1) or Co-Rh-Zr-Al (1/0.2/0.3/1) catalyst by combining Co-Rh-Al (1/0.2/1) hydrotalcite catalyst for the partial oxidation of methane in a dual-bed system. The $N_2O$ conversion activity is drastically reduced in the presence of oxygen in second bed of a dual-bed system over Co-Rh-Al (1/0.2/1) catalyst at $300^{\circ}C$.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.118-121
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• 2007

수소 스테이션의 수소분리정제를 위한 Compact 형 PSA를 연구하였다. 수소 스테이션의 공정과정 중에서 수소 분리를 위한 PSA 장치는 에너지효율면에서 장점을 가지고 있지만 부피가 커서 많은 부지를 차지하는 단점이 있다. 수소 PSA의 이러한 단점을 줄이기 위하여 하나의 흡착탑 안에 다른 흡착탑을 넣는 Dual bed 형태의 Compact형 수소 PSA공정을 연구하였다. Compact형 수소 PSA는 하나의 bed안에 다른 하나의 bed를 넣음으로써 시스템이 차지하는 부피를 줄이는 한편, inner bed와 outer bed사이의 열교환 효과가 나타나기 때문에 그 효율을 높일 수가 있다. Compact형 Dual bed는 활성탄으로 충진하였고 공급 기체로는 4성분 수소 혼합물 ($H_2/CO/CH_4/CO_2$, 69:2:3:26 vol.%)를 사용하였다. 흡착탑의 동특성을 알아보기 위하여 공급유량 7LPM, 흡착압력 9atm의 조건으로 파괴 실험을 수행하였다. 또한, Compact형 흡착탑의 열교환 효과가 PSA공정에 미치는 영향을 보고자 한 쪽 탑에서 흡착을 할 때, 다른 탑에서 탈착이 일어나는 실험을 하였다. 그리고 P/F ratio에 따라 Compact형 PSA 공정 실험을 하고 Compact형 흡착탑과 같은 부피의 일반 두 탑 PSA 공정을 시뮬레이션 값과 비교함으로써 Compact형 PSA의 성능을 알아 보았다. 그 결과 Dual bed PSA는 작은 부피를 차지하는 장점뿐만 아니라 열적 효과로 인하여 기존의 단일 흡착탑 PSA에 비하여 보다 높은 효율을 나타내면서 우수한 수소 분리 성능을 보여주었다.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.214-225
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• 2016

Gasification is one of the important contribution to resource recycling by conversion of biomass to a variety of energy sources such as alcohol, SNG etc., and to global warming prevention by reduction of green house gases such as $CO_2$. The aim of this study is to draw the optimal operation condition of dual fluidized-bed gasifier with biomass fuel, to verify SNG production efficiency and to establish the basis for the domestic commercialization of dual fluidized bed gasification. As a result, dual fluidized-bed gasifier has the optimal conditions at $826^{\circ}C$ with steam input 1,334 g/hr, air input 5.56 L/min. The carbon conversion is 81% and SNG production efficiency was $CH_4$ 92%.

• Journal of Korea Water Resources Association
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• v.34 no.5
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• pp.459-472
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• 2001

The objective of this study is to evaluate the filtration efficiency of deep-bed filters by comparing to single and dual media filters. Pilot-plant tests using four-filter columns were conducted for the comparison of head loss development and filtered water quality. The dual-media filter showed greater initial head loss, but less rate of head-loss development than those of the coarse-sand-0deep-bed filters. For 180 m/day of filtration rate, the dual-media filter produces larger unit production rate by 30-40%, and the turbidities of filtered water were below 0.1 NTU. The initial breakthrough could be effectively controlled by the dual-media filter rather than coarse-sand-deep-bed filters.

• Carbon letters
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• v.2 no.2
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• pp.113-119
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• 2001

The advanced method for $CO_2$capture is currently one of the most important environmental issues in worldwide and it is therefore necessary to have available technologies, which minimize the discharge of $CO_2$ including Carbon-14 from nuclear facilities into the atmosphere. A key aspect of this work is to provide the technically principal data required to improve a $CO_2$ removal system for the utilization of regenerative sorbent use, specifically include suggestions regarding its modified column design (parallel dual-bed assembly), stop-restart operation and the economic feasibility of sorbent use. The removal performance of soda lime and the effects of relative humidity (RH) and packing bed-depth (BD) on $CO_2$ removal were investigated. In a single-bed, it revealed that the utilization of soda lime for $CO_2$ removal at line velocity of 13 cm/sec and bed depth of 12 cm increased with the increased relative humidity up to 85%. However, in the parallel dual-bed assembly applied with the stop-restart operation, a maximum utilization rate of soda lime for $CO_2$ removal was obtained even at 55% of RH and 8 cm of BD, specifically the utilization rate of soda lime by using this $CO_2$ removal assembly was about two-fold superior to that in a single-bed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.163-167
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• 2007

Silver is widely used for catalytic decomposition of hydrogen peroxide, but start-up at room temperature is difficult and cannot withstand at high temperature. In this paper, to overcome these short-comings, a dual catalytic bed which consists of a vaporizer catalyst and a high temperature catalyst was studied. Platinum was selected as the vaporizer catalyst and perovskite type catalyst was selected for the high temperature catalyst. Preliminary test demonstrated start-up capability with non-preheating at room temperature and good thermal stability at high temperature.

• Geomechanics and Engineering
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• v.36 no.2
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• pp.121-130
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• 2024

Many foundation projects are built on red-bed soft rocks, and the damage evolution of this kind of rocks affects the safety of these projects. At present, there is insufficient research on the damage evolution of red-bed soft rocks, especially the progressive process from mesoscopic texture change to macroscopic elastoplastic deformation. Therefore, based on the dual-porosity characteristics of pores and fissures in soft rock, we adopted a cellular automata model to simulate the propagation of these voids in soft rocks under an external load. Further, we established a macro-mesoscopic damage model of red-bed soft rocks, and its reliability was verified by tests. The results indicate that the relationship between the number and voids size conformed to a quartic polynomial, whereas the relationship between the damage variable and damage porosity conformed to a logistic curve. The damage porosity was affected by dual-porosity parameters such as the fractal dimension of pores and fissures. We verified the reliability of the model by comparing the test results with an established damage model. Our research results described the progressive process from mesoscopic texture change to macroscopic elastoplastic deformation and provided a theoretical basis for the damage evolution of these rocks.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.11 no.1
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• pp.29-35
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• 2017

It was hard for a conventional care-bed to be realized to a low-floor position due to a complex actuation mechanism installed under the mattress support platform. In this paper a mechanism design to set a low-floor position as well as to adjust back- and leg-rest angles was proposed. A dual motor was applied to the back- and leg-rest mechanism of which design parameters were determined by an optimal method. An elevation mechanism was also designed to enlarge a limited stroke range up to two times of its original stroke using a pulley mechanism. An evaluation test was performed by five healthy subjects ($24.4{\pm}0.5yrs.$) when going up from a floor position to a preset best position which was set to the 240mm height for a prototype low-floor bed and to the 600mm height for a conventional bed. As a result, the moving distance was 38% lower than the conventional bed when the subject used the low-floor bed. It showed that the low-floor care-bed reduced physical burdens and was effective to assist activities of daily living of the elderly people.