• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.615-619
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• 2009

(+)-$Tr{\ddot{o}}ger$'s base in $Tr{\ddot{o}}ger$'s base racemates that inhibits thromboxane A2($T{\times}A2$) synthase has been used to treat arteriosclerosis. Separation of (+)-$Tr{\ddot{o}}ger$'s base by chromatography has become a major concern. However separation experiments of (+)-$Tr{\ddot{o}}ger$'s base need time and consumables so that simulation with Aspen Chromatography could save time and costs by predicting the efficiency of separation. Injection amount and eluent flow rate were varied to compare the resolutions and yields of TB(-) and TB(+). Highest resolution and yield were attained at the eluent rate of 0.25 mL/min. Isotherms representing the relationship between mobile phase concentration and stationary phase concentration were changed to get the best separation with Ideal Adsorbed Solution(IAS) Statistical Lanmuir isotherms.

• KSBB Journal
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• v.23 no.2
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• pp.135-141
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• 2008

SMB (simulated moving bed) chromatography is a very useful utility for the separation of binary system. We simulated the separation of L-arabinose and L-ribose from the mixture by using lab-scale 4(1-1-1-1)-zone SMB chromatography. Preliminary experiments of PIM (pulse input method) were performed to measure adsorption isotherms of L-ribose and L-arabinose in $NH_2$ HPLC column, and experimental and simulated results from ASPEN chromatography were compared. To find the most suitable separation condition in SMB, we carried out a simulation in $m_2-m_3$ plane base on the triangle theory and calculated operating parameters (flow rate of four zone, switching time and feed concentration and so on) using ASPEN chromatography under the conditions of linear isotherms obtained from PIM.

• Clean Technology
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• v.22 no.4
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• pp.225-231
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• 2016

In this study, modeling and optimization study have been performed to obtain $1,524.58kg\;h^{-1}$ of a solidified NaCl by evaporating a 21.0 wt% of NaCl aqueous solution in order to reduce the steam consumption from $3,139kg\;h^{-1}$ to $496kg\;h^{-1}$ using a two-stage evaporation and a vapor recompression processes. Aspen Plus release 8.8 at AspenTech was utilized for the modeling of two stage evaporation process and PRO/II with PROVISION release 9.4 at Schneider Electric was also used for the simulation of two-stage vapor recompression process with an inter-cooler. For the simulation of the evaporation process containing NaCl aqueous solution, Aspen Plus release 8.8 at AspenTech Inc. was utilized and for the modeling of vapor recompression process PRO/II with PROVISION release at Schneider Electric Inc. For the vapor recompression process, single stage compression and two-stage compression system was compared.

• Journal of Korean Society of Forest Science
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• v.85 no.4
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• pp.656-666
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• 1996

Aspen demand has increased recently in the Great Lakes region in the United States. Since aspen has moved into the region in late 1800's, its growing stock has increased so as to change forestry industry of the Lake States. Intensive timber harvesting and biomass removal may cause nutrient depletion, especially on nutrient-poor sites. Forest nutrients and nutrient cycling were investigated in aspen stands of 7-10, 27-33, and 41-42 year-old growing on sandy soils in Minnesota. Nutrients added to the aspen stands by atmospheric deposition and soil weathering were efficiently absorbed and stored in the tree biomass. Aboveground biomass increased from $24.4t{\cdot}ha^{-1}$ at young stands to $139.2t{\cdot}ha^{-1}$ at mature stands. Nutrients accumulated in the tree biomass showed same magnitude of difference. Nutrients added to the site through atmospheric deposition were in the order of Ca, N, K, Mg, and P. Annual litterfall was greater in older stands. However, the amount of nutrients returned by litterfall was not significantly different among stand ages due to the greater nutrient contents in the litterfall of young stands. Litter decomposition and nutrient release rates were greater at young stands than at older stands. Likewise, nutrient availability was higher in young aspen stands and became lower as the stands grew older. Nutrient leaching loss was minimal at all stand ages. Soil N mineralization was greater at young stands than at older stands. Nutrient cycling process was facilitated in young aspen stands with an increased level of available nutrients, Based on the estimations of nutrient balance and nutrient removal by harvesting, Ca was the most critical element which was likely to be depleted if aspen stands are intensively harvested with short rotations.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2007.10a
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• pp.500-501
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• 2007

• Journal of the Korean Wood Science and Technology
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• v.18 no.1
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• pp.15-23
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• 1990

Roughage feeds were produced from Hyun-aspen (Populus alba $\times$ P. glandulosa) by autohydrolysis. The objectives of this work were to find proper conditions for the treatment of Hyun-aspen by analyzing the compositional change and digestibility and to determine the content of sugar and phenol contained in liquor extracted by digestion. The results of this work were as follows: 1. The proper condition for autohydrolysis of Hyun-aspen chips were $160^{\circ}C$ and 30 minutes in an autoclave. The yield of potential feed from original material and digestibility were 91.3% and 38.9% respectively 2. According to cooking conditions the sugar concentration of extracted solution and the recovery rate of sugar were 0.1~2.5%, 0.3~14.6% respectively. The phenol concentration of extracted solution and the recovery rate of phenol were 0.1~0.3, 0.5~1.8% respectively.

• The Plant Pathology Journal
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• v.15 no.4
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• pp.210-216
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• 1999

TREGRO, a computer simulation model of individual tree growth, was applied to estimate ozone ($\textrm{O}_3$) effects on aspen(Populus tremuloides) growth under ambient and 1.7 times ambient $\textrm{O}_3$ of Seoul in 1996. The three highest $\textrm{O}_3$ (Kuui-dong, Ssangmun-dong, Sungsoo-dong) and the two lowest $\textrm{O}_3$ sites (Mapo-dong, Namgajwa-dong) were evaluated. The current ambient $\textrm{O}_3$ did not affect aspen growth compared to simulation without $\textrm{O}_3$. The only effect was 6.6 percent of total assimilated carbonloss at Ssangmun-dong where the level of $\textrm{O}_3$ was greatest among the 21 sites examined. Decrease as much as 50 percent of total carbon gain was calculated at 1.7 times ambient $\textrm{O}_3$ of the three highest sites. The carbon loss by $\textrm{O}_3$ came from biomass of tissues and total nonstructural cabron (TNC) such as starch and sugar. The most sensitive fraction was TNC and the next was root biomass. Foliage mass was not affected by $\textrm{O}_3$. Structural biomass loss was at best 1 to 3 percent at 1.7 times ambient $\textrm{O}_3$ at the two lowest sites. The daily carbon simulation was affected by $\textrm{O}_3$ mainly during Growth Period 4 (Jul. 21-Oct. 26). Correlations between site, dose, and the simulated responses of aspen (tissue biomass, TNC, respiration, and senescence) ranged from -0.703 to -0.973 depending on the plant responses. The ozone effects on poplar in Seoul are not severe currently, but are probably measurable at Ssangmun-dong. However, severe $\textrm{O}_3$ effects on biomass would occur if $\textrm{O}_3$ levels increase to 1.7 times ambient $\textrm{O}_3$ in Seoul. In addition, v could weaken the trees thus increasing susceptibility to pathogens or insects.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.550-564
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• 2020

Distillation columns are one of the main equipment used for the separation of chemical components in petrochemical process design. However, in spite of the efficient operation in wide range, and the advantage of data collection for equipment verification, the distillation columns are inherently known for high energy consumption and capital cost. Hence, the trade-off analysis needs to be done between investment cost and operation cost to develop the most economical distillation columns. This study was conducted using Aspen Plus, a popular process simulation program, in the pursuit of broad application by as many process engineers as possible. In this paper, design variables for optimization of distillation columns were defined to improve emphatically the design quality with reducing erratic practice of many engineers. In addition, by eliminating unnecessary reviewing step and establishing systematic and efficient procedures, the amount of time for design and human resources were minimized. Aspen Process Economic Analyzers (APEA) program was introduced in order to calculate the investment cost reliably, and the efficient systematic procedure for utilization of APEA was established.

• Journal of Energy Engineering
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• v.8 no.1
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• pp.85-94
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• 1999

전력연구원에서 수행 중인 7 kW 용융탄산염형 연료전지 시스템의 운전 조건과 일치하는 모델을 in-Line FORTRAN 블록을 이용하여 상용 소프트웨어인 ASPEN PLUS로 전산 모사한 결과와 가스 크로마토그래피를 이용하여 분석한 실험적인 값을 비교 분석한 결과 실험치와 거의 일치함을 보였다. 향후 대형 시스템에서 사용하게될 가스 recycle을 위해서 연료극, 공기극의 가스를 recycle할 때와 연료극 가스를 catalytic burner를 이용하여 recycle하였을 때 연료의 전체적인 시스템의 효율 변화를 살펴보았다. 이러한 결과는 용융탄산염 연료전지 대형 시스템의 설계에 중요한 자료가 될 것이다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1996.04a
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• pp.65-70
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• 1996

본 연구는 상용공정해석용 프로그램으로서 고체 반응물을 포함하고 있는 공정을 해석할 수 있는 ASPEN(Advanced System for Process Engineering) 코드를 이용하여 IGCC BSU 실험플랜트를 모사하고 실제 실험 결과와 비교하였으며, IGCC BSU 시스템을 수정보완하여 가스정화공정을 도입하고 석탄가스화기에서 생성된 생성가스에 대해 발전 연료로서의 타당성 및 적합성 여부를 살펴보고 이 자료를 토대로 향후 IGCC 플랜트의 scale-up 및 실용플랜트에 대한 이해를 도모코자 한다. 또한 환경적인 측면에서 IGCC BSU에서 방출되는 슬랙, 비산재 및 flare stack을 통한 SOx 및 NOx 등의 방출량을 살펴보았다.