• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.167-174
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• 2008

In this study, flutter analyses for supercritical airfoil have been conducted in transonic region. Advanced computational analysis system based on computational fluid dynamics (CFD) and computational structural dynamics (CSD) has been developed in order to investigate detailed static and dynamic responses of supercritical airfoil. Reynolds-averaged Navier-Stokes equations with Spalart-Allmaras (S-A) and SST ${\kappa}-{\omega}$ turbulence models are solved for unsteady flow problems. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of cascades for fluid-structure interaction (FSI) problems. Also, flow-induced vibration (FIV) analyses for various supercritical airfoil models have been conducted. Detailed flutter responses for supercritical are presented to show the physical performance and vibration characteristics in various angle of attack.

• 한국항공운항학회지
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• 제17권2호
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• pp.8-17
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• 2009

In this study, flutter analyses for supercritical airfoil have been conducted in transonic region. Advanced computational analysis system based on computational fluid dynamics (CFD) and computational structural dynamics (CSD) has been developed in order to investigate detailed static and dynamic responses of supercritical airfoil. Reynolds-averaged Navier-Stokes equations with Spalart-Allmaras (S-A) and SST ${\kappa}-{\omega}$ turbulence models are solved for unsteady flow problems. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of cascades for fluid-structure interaction (FSI) problems. Also, flow-induced vibration (FIV) analyses for various supercritical airfoil models have been conducted. Detailed flutter responses for supercritical are presented to show the physical performance and vibration characteristics in various angle of attack.

• 한국수소및신에너지학회논문집
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• 제30권4호
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• pp.297-302
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• 2019

In this paper, the power generation efficiency increase has been studied for a Rankine cycle using both supercritical carbon dioxide as a working fluid and LNG as a coolant with PRO/II with PROVISION release 10.0 from Aveva company. Peng-Robinson equation of the state model with Twu's alpha function was selected for the modeling of the power generation cycle using LNG cold heat. Power generation efficiency was increased from 24.82% to 57.76% when using LNG as a coolant for supercritical carbon dioxide power generation cycle.

• Fibers and Polymers
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• 제5권2호
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• pp.160-169
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• 2004

Polystyrene/layered silicate nanocomposites were prepared by melt intercalation. To examine the distribution of the clay in polymer matrix, small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) were used. Intercalated nanocomposites were obtained and their rheological properties were investigated. Microcellular nanocomposite foams were produced by using a supercritical fluid. As clay contents increased, the cell size decreased and the cell density increased. It was found that layered silicates could operate as heterogeneous nucleation sites. As the saturation pressure increased and the saturation temperature decreased, the cell size decreased and the cell density increased. Microcellular foams have different morphology depending upon the dispersion state of nanoclays.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.669-675
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• 1991

Based on process analysis as well as extensive operation experience, two fuzzy expert control algorithms, for startup and control, are proposed for a supercritical fluid extraction process which has high interacting multivariable structure. In the proposed algorithms, a new simple defuzzification method which only requires four fundamental arithmetic rules is also presented. Through numerical simulations, control performance using the proposed control algorithm is compared with that of a different fuzzy algorithm by an other researcher and that of conventional PID-type controllers which are tuned by well-known optimal criteria. Also, the proposed control algorithm has been tested to the bench scale supercritical fluid extraction process. As a consequence, the proposed fuzzy expert controller has shown fast and robust control performance while the other controllers show sluggish and/or highly oscillatory responses.

• 한국문화재보존과학회:학술대회논문집
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• 한국문화재보존과학회 2004년도 제20회 발표논문집
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• pp.66-71
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• 2004

When waterlogged wood dries up, it shrinks largely. And it is hard to recover original shape. Therefore it happens to lose the value of wood remains frequently. This paper studied how far dried waterlogged wood can recover original shape. Shape recovering course and extent are thoroughly investigated after waterlogged wood of Pinus densiflora, Quercus serrata and Styrax japonica oven-dries and instills varieties of test solution. At 1- step, oven-dried samples infiltrated by chlorous acid sodium or sodium hydroxide solution. At 2- step, wood tissues of samples were swelled by the fast decompression after infiltrating $CO_2-supercritical$ fluid at high pressure. The study investigated the possibility of shape recovering in waterlogged wood. Shape recovering rate is different with solution and wood species. Sample of sodium hydroxide solution doesn't swell anymore when using $CO_2-supercritical$ fluid. In general, the sample of sodium hydroxide solution has higher Shape recovering rate than $CO_2-supercritical$ fluid solution treated by chlorous acid sodium.

• 한국연초학회지
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• 제23권1호
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• pp.65-70
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• 2001

In order to compare the extraction patterns of main components from the raw material between the extraction methods, the aerial parts (dried stem, leaves, and flowers) of Agastache rugosa were extracted by SDE simultaneous steam distillation & extraction) and SFE (supercritical fluid extraction). Volatile components of essential oil and extract were identified by GC and GC-MSD. The contents of essential oil extracted by SDE were 0.49% in aerial part of Agastache rugosa on dry basis. Major components were methyl chavicol(27.2%), isomenthone(24.6%), hexadecanoic acid(13.0%). menthone (5.5%) among 32 kinds of components confirmed in essential oil. On the other hand, the contents of SFE extracts revealed 3.21% on dry basis, 6 times higher than those of SDE. Major components were isomenthone(15.3%), hexadecanoic acid(13.7%), methyl chavicol(12.6%), benzoic acid(3.8%) among 33 kinds of components identified in extract.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 추계학술발표회
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• pp.47-48
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• 2005

• Bulletin of the Korean Chemical Society
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• 제35권10호
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• pp.3107-3110
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• 2014

• Applied Biological Chemistry
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• 제41권5호
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• pp.363-366
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• 1998

홍화로부터 초임계 이산화탄소를 이용하여 황색소(safflower yellow)를 추출할 때의 최적 조건을 조사하였다. 여러 온도$(40,\;50,\;60,\;70,\;80^{\circ}C)$와 압력(2000, 3000, 4000, 5000 psig) 조건에서 추출을 하였으며 수율을 증가시키기 위해 물을 보조용매(0, 3, 6, 10, 14 wt%)로 하여 실험을 수행하였으며 색소분석은 spectrophotometer를 이용하였다. 황색소의 추출 수율은 $60^{\circ}C$, 4000 psig에서 가장 높게 나타났다. 보조용매로 물을 사용하였을 때는 10 wt%일 때 황색소의 추출이 가장 잘 되었고 그 이상에서는 오히려 추출량이 감소하는 경향을 보였다. 또한 시료의 수분함량은 초임계 유체 추출 시 수율과 밀접한 관련이 있는데 홍화의 황색소 추출 시에도 시료의 수분함량이 낮을수록 수율이 증가함을 알 수 있었다. 아울러 초임계 유체를 이용하여 최적 조건에서 추출한 경우 황색소의 수율은 용매로 추출한 경우에 비해 6% 정도 증가하였다. 상기의 결과로 초임계 이산화탄소 추출법은 홍화로부터 황색소의 추출에 적합하다는 것을 확인할 수 있었다.