• Macromolecular Research
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• 제16권1호
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• pp.6-14
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• 2008

Polypropylene (PP)-layered silicate nanocomposites were developed using a new processing method involving a supercritical carbon dioxide ($scCO_2$)-assisted co-rotating twin-screw extrusion process. The nanocomposites were prepared through two step extrusion processes. In the first step, the PP/clay mixture was extruded with $CO_2$ injected into the barrel of the extruder and the resulting foamed extrudate was cooled and pelletized. In the second step, the foamed extrudate was extruded with venting to produce the final PP/clay nanocomposites without $CO_2$. In this study, organophilic-clay and polypropylene matrix were used. Maleic anhydride grafted polypropylene (PP-g-MA) was used as a compatibilizer. This study focused on the effect of $scCO_2$ on the dispersion characteristics of the clays into a PP matrix and the rheological properties of the layered silicate based PP nanocomposites. The dispersion properties of clays in the nanocomposites as well as the rheological properties of the nanocomposites were examined as a function of the PP-g-MA concentration. The degree of dispersion of the clays in the nanocomposites was analyzed by X-ray diffraction and transmission electron microscope. Various rheological properties of the nanocomposites were measured using a rotational rheometer. In the experimental results, the $scCO_2$ assisted continuous manufacturing extrusion system was used to successfully produce the organophilic-clay filled PP nanocomposites. It was found that $scCO_2$ had a measurable effect on the clay dispersion in the polymer matrix and the melt intercalation of a polymer into clay layers.

• 한국축산식품학회지
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• 제33권5호
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• pp.581-586
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• 2013

The objective of this study was to investigate the effects of supercritical carbon dioxide (SC-$CO_2$) treatment on meat quality and sensory evaluation of marinated pork. Meat marinated in two traditional Korean marinades, soy sauce and hot-pepper paste, and raw marinated meat were then treated with 7.4, 12.2, or 15.2 MPa $CO_2$ at $31.1^{\circ}C$for 10 min. The SC-$CO_2$ treatments had no effect on the meat pH (p>0.05) or Warner-Bratzler shear force (p>0.05). There was no significant difference (p>0.05) in the total loss (sum of treatment loss and cooking loss) between the control and SC-$CO_2$ treated samples at 15.2 MPa (soy sauce marinated pork: 21.78 vs. 18.97%; hot-pepper marinated pork: 21.61 vs. 18.01%). After the SC-$CO_2$ treatment, lighter surface colors were observed in the treatment samples compared to those of the control samples (p< 0.001). However, tasting panelists were unable to distinguish a difference in color or in overall acceptability of the control and treatment (p>0.05). In the case of soy sauce marinated pork, when SC-$CO_2$ applied at 15.2 MPa and $31.1^{\circ}C$for 10 min, treatment samples showed a tenderer meat than the control samples. Therefore, the SC-$CO_2$ treatment conditions had no adverse effects on the sensory quality characteristics of the marinated meat products.

• KSBB Journal
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• 제16권3호
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• pp.233-236
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• 2001

원료 의약품의 경우 정제된 최총제품 내려 잔류용매 제거는 매우 중요하다. 일반적인 진공건조 방법에 의한 제품생산시 case hardening 효과 때문에 잔류용매획 제거가 상당히 어렵다. 본 연구에서는 초임제 이산화탄소를 아용하여 정제된 paclitaxel 내의 methylene chloride와 methanol 의 잔류용매를 효과적으로 제거하였다. 초임계 이산화탄소를 이용하여 $40^{circ}C$, 80 bar에서 30분간 조업하였율 경우 최초 최종제품 내 잔류 용매인 methylene chloride 와 methanol이 각각 5,869 ppm과 2,135 ppm에서 468 ppm과 403 ppm으로 줄어 ICH 규정치를 충분히 만족시킬 수 있다. 이러한 연구 결과는 초임계 유체의 새로운 응용 분야를 개척하고 많은 원료 의약품의 잔류용매 제거에 효과적으로 사용할 수 있을 것으로 사료된다.

• 한국콘텐츠학회논문지
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• 제16권5호
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• pp.660-667
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• 2016

원자력발전 등에 기인한 방사성 오염물질들은 대부분 제염과정을 통하여 방사능과 그 부피를 줄이는데, 물을 주로 사용하는 기존의 방사성 물질 제염방법은 많은 양의 2차 폐기물을 발생시킨다. 본 연구에서는 용매로 이산화탄소의 특성을 이용하여 폐기물 저감에 효과적인 제염 방법을 적용해보았다. 이를 위해 본 연구에서는 우선 원자력 오염물질의 제염 대상을 금속 이온, 금속과 금속산화물로 분류하여 두 가지 방법을 적용하였다. 전자의 경우 계면활성제 킬레이트법을 이용하여 제염하였다. 제염대상 핵종으로는 Sr, Co, Nb, Zr을 선정하였다. Sr과 Co는 각각 핵분열 생성물과 방사화 부식 생성물의 대표 핵종이고 Nb과 Zr은 오염된 방호복에서 가장 많은 방사능을 차지하는 핵종이다. Static Extraction을 통하여 Sr은 최고 97%, Nb과 Co, Zr은 각각 79%, 73%, 64%의 추출율을 얻었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.471-475
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• 1988

Pressure and flowrate control systems for a supercritical extraction process are designed and analyzed. To do this, the dynamic model was first set up using the performance equations of control valves, CO2 compressor and the state equation of the supercritical fluid. Using this model, optimum pairs of manipulated and controlled variable which give least steady stat interaction are determined though the relative gain analysis.

• Bulletin of the Korean Chemical Society
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• 제30권8호
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• pp.1760-1766
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• 2009

Enzymatic syntheses of water soluble Bakuchiol glycosides were carried out in di-isopropyl ether organic media using amyloglucosidase from Rhizopus mold. The reactions were carried out under conventional reflux conditions and in supercritical $CO_2$ atmospheric conditions. Out of the eleven carbohydrate molecules employed for the reaction, D-glucose, D-ribose and D-arabinose gave glycosides in yields of 9.0% to 51.4% under conventional reflux conditions. Under supercritical $CO_2$ atmosphere (100 bar pressure at 50 ${^{\circ}C}$), bakuchiol formed glycosides with Dglucose, D-galactose, D-mannose, D-fructose, D-ribose, D-arabinose, D-sorbitol and D-mannitol in yields ranging from 9% to 46.6%. Out of the bakuchiol glycosides prepared, 6-O-(6-D-fructofruranosyl)bakuchiol showed the best antioxidant (1.4 mM) and ACE inhibitory activities (0.64 mM).

• 대한기계학회논문집B
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• 제40권11호
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• pp.737-744
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• 2016

인쇄기판형 열교환기는 집적도가 높고 구조적으로 견고하여 차세대 초임계 이산화탄소 발전 사이클용 열교환기로 각광받고 있다. 본 논문에서는 열원측과 열침측의 채널 크기가 상이한, 획기적인 형태의 인쇄기판형 열교환기에 대한 수치적 연구 결과를 보고한다. 초임계 이산화탄소를 작동유체로 하는 인쇄기판형 열교환기에 대해서 형상변수에 따른 전열성능을 해석하였으며, 그 결과 열원 혹은 열침측의 채널 직경이 증가함에 따라 유속 감소에 의해 전열성능이 단조적으로 감소하는 것을 확인하였다. 채널간격의 경우 열교환기의 전열성능에 크게 영향을 미치지 않는 것으로 나타났다. 또한 수력직경이 동일할 경우 채널 단면의 모양은 전열성능에 괄목할 만한 영향을 미치지 않는 것으로 나타났다.

• 한국식품저장유통학회지
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• 제7권2호
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• pp.177-183
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• 2000

A supercritical fluid extraction was performed for the extraction of phenolics from grape seeds which up to now have been discarded. The optimum condition for extraction process was predicted through response surface methodology using central composit experimental design. The extraction amount of grape seed phenolics was increased by increasing extraction temperature, pressure, and concentration of co-solvent (ethanol). The optimum extraction conditions were 84.83$^{\circ}$C, 51.50MPa and 1.27% ethanol. The yield of phenolics using SFE was higher with 3 folds than ethanol and 4 folds than hexane but less than 80% methanol. In the respects of food poisoning, the approved solvents were restricted to ethanol and hexane. So, SFE for extraction of phenolics could be powerful alternative method for solvent extraction.

• 한국식품과학회지
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• 제36권2호
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• pp.317-320
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• 2004

Curcumin의 추출효율은 에탄을 추출방법이 가장 높았고, 항산화효과는 에탄올, 초임계, 열수 추출물 순으로 나타났다. Ames의 mutagenicity test를 실시한 결과 각각의 추출물은 돌연변이원이 없는 것으로 확인되었고, TA98에 직접변이원 2-NF 처리시 초임계 추출물의 저해율이 20.1%로 에탄올과 열수 추출물에 비하여 가장 높은 항돌연변이 효과를 나타냈다. 또한 간접 변이원 2-acetamidofluorene($10\;{\mu}L/plate$; Sigma Co.; 2-AF)에 대한 항돌연변이 효과를 알아본 결과 2-AF로 유도된 TA98은 초임계 추출물을 0.1 mL/plate로 처리시 항돌연변이의 효과는 12.2%였으며, 알코올 추출물과 열수 추출물의 경우는 항돌연변이 효과가 나타나지 않았다. Nitrite의 분해능의 경우에 있어서도 에탄올 및 열수 추출물에 비하여 초임계 추출물이 높은 분해율을 나타냈으며 pH 1.2에서 가장 높은 분해율을 보였다. 이와 같이 초임계를 이용해 추출한 curcumin은 항산화효과, nitrite 분해능, 항돌연변이효과 등에 대한 생리활성 기능을 보였으며, 기존의 에탄올이나 열수 추출법에 비하여 유사하거나 더 높은 생리활성 효과가 나타나기도 했다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.821-826
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• 2009

Due to environmental concerns $CO_2$ has been reintroduced as a potential candidate to replace HFCs in refrigeration systems. Oils are always required in a vapor-compression cycle, and thus actual working fluid in the system is $CO_2$-oil mixtures even though the oil concentrations are low at the heat exchangers and the expansion device. The cooling heat transfer coefficients for $CO_2$-oil mixtures under supercritical condition are required to designing of the gas cooler in the $CO_2$ refrigeration system properly. In the present study, the gas cooling heat transfer coefficients for $CO_2$-PEC9 was estimated by using the Gnileinski correlation, and the Kim and Ghajar model through the previous prediction models for the thermo-physical properties of $CO_2$-oil mixture. The Gnileinski correlation was used when the oil wt.% in the mixture is less than 1.0, and for the higher oil concentration the Kim and Ghajar model was applied. The estimated results agree with the experimental results conducted by the Dang et al.