• Journal of the Korean Wood Science and Technology
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• 제34권5호
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• pp.104-110
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• 2006

We investigated why aspen extractives are more resistant in kraft pulping than pine extractives. Residual extractives content in aspen kraft pulps were 0.5~1.1% compared with 0.1~0.2% in pine pulps. This different response arises from the different composition of extractives in wood chips. Resin acids in pine were almost completely removed in kraft pulping but those are not existence in aspen. Slower saponification of aspen steryl esters resulted from different chemical structure of aspen steryl esters. Main sterols in aspen steryl esters were 24-methyl cyclolanostenol which was highly resistant to alkaline hydrolysis with its characteristic steric hindrance. Sterols in aspen were not well removed in kraft pulping. The relative composition of sterol in aspen kraft pulps was increased with increasing pulping time. The presence of fatty acids in aspen kraft pulps is considered to unusual. Fatty acids in alkaline are supposed to be well ionized and removed well in the washing stage. Nevertheless, there were significant amount of fatty acids remaining in aspen kraft pulps.

• Asian-Australasian Journal of Animal Sciences
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• 제1권4호
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• pp.195-199
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• 1988

Two experiments were conducted to evaluate the nutritive value of a diet containing 20% alkaline hydrogen peroxide(AHP) treated aspen sawdust for ruminants. In experiment 1, sheep fed treated aspen(treated) had higher (p < 0.05) average daily gain and improved feed/gain ratio compared to animals fed untreated aspen (untreated), Apparent NDF and ADF digestibilities of treated aspen were higher (p < 0.05) than for untreated material. A similar trend was observed for DM, organic matter and cellulose digestibilities coefficients. In experiment 2, the soluble and degradable DM and crude protein (CP) fractions tended to increase with AHP treatment. Treatment also increased (p<0.05) the degradation rate of the degradable fraction. Results of these experiment indicate that AHP treatment results in a substantial improvement in the extent of utilization of aspen sawdust by ruminants.

• Korean Chemical Engineering Research
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• 제48권1호
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• pp.88-92
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• 2010

DNA 구조를 밝히기 위해 의학, 약학 그리고 생명과학분야 등에서 활발한연구가 이루어지고 있다. 그 중 DNA의 염기쌍은 생명체의 정보 전달에 매우 중요한 역할을 하므로 염기쌍의 집중적인 분석이 필요하다. 그래서 DNA의 염기쌍 중 하나인 구아닌과 시토신을 선택하여 분석 실험을 하였다. 구아닌과 시토신의 분석은 Aspen chromatography 전산모사와 HPLC(High Performance Liquid Chromatography) 실험을 통하여 이루어졌다. Aspen Chromatography(ver. 2006 Aspen Tech. U.S.A)로 시료농도, 이동상 유속 그리고 이론단수를 변화시켜 전산모사하였다. HPLC 실험은 $C_{18}$ HPLC column 칼럼과 이동상 water/methanol/acetic acid 혼합액(90/10/0.1)을 이용하여 시료의 주입 농도와 이동상 속도를 변화시켰고 구아닌과 시토신의 크로마토그램의 분리도와 이론단수를 비교하였다. 실험과 전산모사 크로마토그래피 결과가 비교적 일치하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제5권4호
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• pp.635-641
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• 1992

The influence of alkaline hydrogen peroxide (AHP) and peracetic acid treatment on in sacco digestion of aspen was evaluated in three non-lactating ruminally cannulated Holstein cows fed a diet containing 90% forage and 10% concentrate on a DM basis. AHP treatment decreased lignin concentration by 40 to 60% resulting in increased concentrations of neutral detergent fiber (NDF), acid detergent fiber (ADF) and cellulose. Lignin concentrations in peracetic acid treated samples were less than 10% of values for control samples. In sacco disappearance rates of aspen DM, NDF, ADF and cellulose increased (p<.05) with AHP and peracetic acid treatment. Effective degradability of DM, NDF, ADF and cellulose were determined at a ruminal outflow rate of $.05h^{-1}$. Effective degradabilities of AHP treated aspen were approximately three-fold greater and peracetic acid treated samples five-fold greater than untreated control samples. For all parameters measured, peracetic acid treatment resulted in higher (p<.05) digestion coefficients than AHP treated aspen. Results demonstrate that peracetic acid or AHP treatment can enhance the nutritive value of aspen sawdust for ruminants to a level comparable to that reported for many forages.

• 펄프종이기술
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• 제37권3호
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• pp.74-80
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• 2005

The compositions of residual extractives in woodmeal, unbleached and oxygen-delignified aspen kraft pulps were investigated with gas chromatography(GC) and gas chromatography-mass spectrometry (GC-MS) with focus on fate of extractives in kraft pulping and oxygen delignification. Steryl esters and shorter retention time (shorter than palmitic acid) extractives were main extractives in aspen woodmeal. Shorter retention time extractives were well removed in kraft pulping. Sterol esters were hydrolyzed to sterols and fatty acids. Sterols and fatty acids were two major extractives classes in unbleached kraft pulps. Linoleic acid was main fatty acids in unbleached pulps compared with palmitic acid which is generally found in aspen woodmeal. Sterolsand fatty acids were also two major extractives classes in oxygen-delignified kraft pulps. However, linoleic acid was well removed in oxygen delignification.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.207-207
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• 2009

Aspen plus는 Aspentech사에서 개발한 공정모사용 프로그램으로서 다양한 화학종의 열역학적 자료를 기반으로 공정설계, 공정최적화, 공정모니터링 등 공정개발에 활용되고 있다. 연료개질기는 수증기 개질반응, 수성가스전이반응, 선택적화학반응으로 구성된 소규모 수소생산공정에 해당된다. 따라서 Aspen 전산모사를 통해 다양한 조건에서의 운전결과를 모사하여 개질기에 미치는 영향을 분석함으로써 운전조건을 최적화 할 수 있다. 연료개질기의 성능에 영향을 미치는 주요인자는 주로 수증기개질 촉매층 출구온도 및 수증기/탄소 비이다. 수증기개질 촉매층의 출구온도를 $660{\sim}740^{\circ}C$로 변화시키면서 개질가스의 조성, 카본 전환율, 개질효율 등을 비교 분석하였다. 또한 수증기/탄소 비를 3~5의 범위에서 변화시키면서 영향을 살펴보았다. 수증기개질 촉매층의 온도가 높을수록 수소생산량이 증가에 따른 효율 증가가 나타났으며 수증기/탄소 비가 증가할 경우에도 개질효율에 긍정적인 영향을 미치는 것을 확인하였다. 하지만 실제 개질기의 운전에서는 소재의 제약에 따라 운전 온도에 제약이 있으며 수증기/탄소비의 증가 역시 개질기의 부피 증가로 이어지는 단점이 있다는 것을 고려해야 한다. 따라서 반응기 재질, 크기, 운전온도와 개질효율과의 상관관계를 파악하여 개질기의 특성을 최적화 하여야 한다.

• Korean Chemical Engineering Research
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• 제49권4호
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• pp.423-431
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• 2011

최근 대체에너지에 대한 관심이 높아짐에 따라 수소에너지를 기반으로 하는 차세대 발전 장치인 연료전지 관련 기술 개발이 활발하게 이루어지고 있다. 특히, 고온 연료전지의 대표적인 형태인 용융 탄산염 연료전지(MCFC: Molten Carbonate Fuel Cell, 이하 MCFC)는 전력사업용으로의 높은 가능성을 인정받아 화석연료를 대체할 발전방식으로 평가 받고 있다. 본 연구에서는 Aspen Custom Modeler($ACM^{TM}$)에서 평형반응식을 이용하여 스택 모델을 구성한 후, Aspen $Plus^{TM}$에서 BOP(Balance of Plant) 시스템과 스택을 연결하여 전체 MCFC 발전 시스템의 정상상태를 모사하였다. 모델의 유효성을 입증하기 위해서 전류밀도, 연료이용률, S/C ratio, 재순환 흐름 비와 같은 주요 조업변수에 따른 셀 전압, 전력, 효율 등 시스템의 성능을 분석하였다. 그리고 Aspen $Dynamics^{TM}$에서 PID제어 방식을 적용하여 제어루프를 구성하였고 부하변화, 설정점 변화, 재순환 흐름비 변화에 따른 각각의 사례연구를 통하여 전체 시스템의 성능변화를 예측하였다. 그 결과 연료이용률과 전류밀도의 변화에 따른 전체 시스템의 최대 발전 효율 및 출력전압을 위한 운전조건을 제안하였다.

• 한국군사과학기술학회지
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• 제19권2호
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• pp.211-217
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• 2016

The fuel cell based auxiliary power unit (APU) is promising for power source of armed vehicles due to its silence and high efficiency. Especially, the on board hydrogen generation and fed to fuel cell system was core technology of this power system. In this study, we analyzed the performance of the Auto thermal reactor (ATR) that produce the hydrogen from the fuel, integrated High temperature polymer electrolyte fuel cell (HT-PEFC) by Aspen plus software. The fuel was designed as a n-dodecane for analysis of military fuel (JP-8).

• 펄프종이기술
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• 제43권1호
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• pp.29-35
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• 2011

Since the role of lignin in the wood cell wall is to keep integrity and structure rigidity of lignocellulosic substrate, lignin of the cell wall has to be destroyed before enzymatic hydrolysis of wood polysaccharides. The aspen wood meals were delignified with ozone in acidic condition. The chemical characteristics of wood meal were investigated. The 60% of lignin and almost zero % of polysaccharides in aspen wood meal was degraded with 10min. ozone treatment. The phenolic hydroxyl groups of lignin in ozonated wood meal were increased with ozonation time. The sugar composition of ozonated wood meal showed that the hemicellulose was more susceptible to ozonation than cellulose. The yield of aldehyde was increased in some degree with 10min. ozone treatment and decreased with longer ozone treatment.

• 한국수소및신에너지학회논문집
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• 제32권6호
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• pp.489-496
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• 2021

The performandce of polymer electrolyte membrane fuel cell depends on the effective management of heat and product water by the electrochemical reaction. This study is designed to investigate the parametric change of heat management along the channel of polymer electrolyte membrane. The model was developed by an aspen custom modeler that it can solve differential equation with distretization model. The model can simulate water transport through the membrane electrolyte that is coupled with heat generation. In order to verify the model, it is compared with the experimental data. The water transport behavior is then evaluated with the simulation model.