• 한국세라믹학회지
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• 제35권10호
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• pp.1049-1054
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• 1998

In order to fabricate ideal powders new processing is necessary in which the solute atoms in solution ra-pidly move to mix each other to the degree of molecular level the viscosity of solution should be low not to effect the moving of solute atoms and the powders could be directly obtained as crystalline. Supercritical fluid is defined as condensed gas sated up to its critical pressure and temperature. In this paper su-percritical fluid methods were studied as a new ceramic processing of powder preparation. The crystalline powders of TiO2 which are useful for electronic ceramic materials were fabricated by hydrolysis of titanium (IV) ethoxide using ethanol as a supercritical fluid at the condition of 270$\pm$3$^{\circ}C$, 7.3 MPa for 2hr. The cry stalline anatase powders could be directly obtained and its primary particle size was 20 min.

• 대한화학회지
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• 제37권6호
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• pp.604-611
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• 1993

초임계 유체 크로마토그래피(Supercritical Fluid Chromatography, SFC)는 종래의 크로마토그래피 방법으로 분석하기 어려운 물질을 분석해 내는 기술로써 발전이 되어왔다. 그러나, SFC에서 이동상으로 많이 사용되고 있는 초임계 C$O_2$는 용매로써 특성이 n-hexane과 매우 비슷하여 극성이 큰 시료들을 용출(elution)시키기가 어렵다. 이러한 점을 해결하기 위하여 초임계 C$O_2$에 극성을 지닌 물질 즉, 변형제(modifier)를 섞어서 이동상으로 사용할 수 있다. 본 연구에서는 초임계 C$O_2$에 변형제를 첨가시키는 새로운 방법을 개발하였고, 변형제로써 초임계 C$O_2$에 첨가된 수분(H$_2O$)의 양을 perfluorosulfonate ionomer(PFSI) film을 이용해 만든 amperometric microsensor로써 측정하였다. 이와같은 방법을 사용함으로써 포화 column보다 상당히 긴 시간동안 일정하게 수분을 첨가할 수 있었고, 실제로 이 방법을 사용하여 순수한 C$O_2$ 이동상만으로는 분리하기 어려운 몇 가지 살균제와 살충제에 적용한결과 좋은 크로마토그램을 얻었다.

• 한국염색가공학회지
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• 제31권1호
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• pp.48-64
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• 2019

With evolution in the production environment of the textile industry, the need for non-water-based dyeing technologies and eco-friendly process facilities in the dyeing and processing stages has increased. In recent years, supercritical fluid dyes have been developed and commercialized in Europe, centering on this demand. However, so far, such dyes have been mainly applied in the processing of PET fibers. Basic research has mainly involved investigation of dyeing by supercritical carbon dioxide or solubility of such dyes, and more in-depth research should be continuously carried out. In this review, we describe the types and characteristics of supercritical fluids that exhibit specific properties at pressures and temperatures over the critical point. In addition, the state of the art in the dyeing and processing technology using supercritical fluids and associated, processing problems, environmental regulation, and wastewater treatment issues are described in detail. We hope this review can contribute to the supercritical fluid technology being further developed as an environment friendly dyeing processing method. Furthermore, we expect that the technique can be used as a means of ensuring different, high-quality dyed products.

• 분석과학
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• 제21권5호
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• pp.392-396
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• 2008

산겨릅나무(Acer tegmentosum)는 지방간, 가염, 간경변증, 간암에 뚜렷한 치료 작용이 있으며, 특히 간에 쌓인 독을 풀고 간세포를 살리는 효능이 있어 약용으로 많이 사용된다. 그러나 산겨릅나무 줄기에는 독성물질이 있어 안전성, 오남용 등의 문제점을 가지고 있다. 그래서 산겨릅나무 줄기의 독성물질을 제거하고 독성 물질에 대한 연구를 활발히 하기 위해 먼저 초임계유체 추출기법(SFE, Supercritical Fluid Extraction)을 이용하였다. 초임계유체 추출에서 최적의 실험 조건은 압력 100 bar, 추출온도 $40^{\circ}C$로 구성하고, 초임계 $CO_2$의 유속 3 mL/min과 modifier인 에탄올의 유속 0.2 mL/min 이다.

• Bulletin of the Korean Chemical Society
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• 제17권6호
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• pp.496-498
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• 1996

Fatty alcohol ethers, nonionic surfactants which are used as general purpose emulsifiers were separated by use of water-modified carbon dioxide mobile phase in capillary supercritical fluid chromatography. Much greater peak intensities and improved separation were observed in the chromatogram with on-line modified mobile phase than with pure CO2. A simple method for the preparation of on-line modified mobile phase is also introduced.

• Journal of Ginseng Research
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• 제41권3호
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• pp.428-433
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• 2017

Background: In this study, the fermentation of ginseng seeds was hypothesized to produce useful physiologically-active substances, similar to that observed for fermented ginseng root. Ginseng seed was fermented using Bacillus, Pediococcus, and Lactobacillus strains to extract ginseng seed oil, and the extraction yield, color, and quantity of phenolic compounds, fatty acids, and phytosterol were then analyzed. Methods: The ginseng seed was fermented inoculating 1% of each strain on sterilized ginseng seeds and incubating the seeds at $30^{\circ}C$ for 24 h. Oil was extracted from the fermented ginseng seeds using compression extraction, solvent extraction, and supercritical fluid extraction. Results and Conclusion: The color of the fermented ginseng seed oil did not differ greatly according to the fermentation or extraction method. The highest phenolic compound content recovered with the use of supercritical fluid extraction combined with fermentation using the Bacillus subtilis Korea Food Research Institute (KFRI) 1127 strain. The fatty acid composition did not differ greatly according to fermentation strain and extraction method. The phytosterol content of ginseng seed oil fermented with Bacillus subtilis KFRI 1127 and extracted using the supercritical fluid method was highest at 983.58 mg/100 g. Therefore, our results suggested that the ginseng seed oil fermented with Bacillus subtilis KFRI 1127 and extracted using the supercritical fluid method can yield a higher content of bioactive ingredients, such as phenolics, and phytosterols, without impacting the color or fatty acid composition of the product.

• Nuclear Engineering and Technology
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• 제54권9호
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• pp.3540-3550
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• 2022

The supercritical carbon dioxide (S-CO₂) Brayton cycle is an important energy conversion technology for the fourth generation of nuclear energy. Since the printed circuit heat exchanger (PCHE) used in the S-CO₂ Brayton cycle has narrow channels, Rayleigh-Bénard (RB) convection is likely to exist in the tiny channels. However, there are very few studies on RB convection in supercritical fluids. Current research on RB convection mainly focuses on conventional fluids such as water and air that meet the Boussinesq assumption. It is necessary to study non-Boussinesq fluids. PRB convection refers to RB convection that is affected by horizontal incoming flow. In this paper, the computational fluid dynamics simulation method is used to study the PRB convection phenomenon of non-Boussinesq fluid-supercritical carbon dioxide. The result shows that the inlet Reynolds number (Re) of the horizontal incoming flow significantly affects the PRB convection. When the inlet Re remains unchanged, with the increase of Rayleigh number (Ra), the steady-state convective pattern of the fluid layer is shown in order: horizontal flow, local traveling wave, traveling wave convection. If Ra remains unchanged, as the inlet Re increases, three convection patterns of traveling wave convection, local traveling wave, and horizontal flow will appear in sequence. To characterize the relationship between traveling wave convection and horizontal incoming flow, this paper proposes the relationship between critical Reynolds number and relative Rayleigh number (r).

• 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.

• Journal of Acupuncture Research
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• 제28권2호
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• pp.89-95
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• 2011

Objectives : The purpose of this study was to investigate the composition of Rehmannia glutinosa's essential oils with Rehmanniae Radix herbal acupuncture Methods : I obtained the essential oils of Rehmannia Radix by hydrodistillation extraction method and supercritical fluid extraction(SFE) method, and then I analyzed those by GC/MS(gas chromatography/mass spectrum). Results : 1. With GC(gas chromatography) and GC/MS(gas chromatography/mass spectrum) analysis. I identified 9 compounds in the Rehmanniae Radix's essential oil obtained through the SFE method. The main compounds were as follows : Hexachloroethane(2.24%), N-Butyl-benzenesulfonamide(2.05%), hexadecanoic acid(1.93%), hexadecanoic acid, ethyl ester(3.49%), 9,12-Octadecadienoic acid(z,z)(2.70%), (9E)-9-Octadecenoic acid(6.14%), ethyl linoleate(4.43%), ethyl oleate(5.80%). 2. I failed to get Rehmanniae Radix's essential oil obtained through the hydrodistillation method. 3. With GC(gas chromatography) and GC/MS(gas chromatography/mass spectrum) analysis. I identified 4 compounds in the Rehmanniae Radix's essential oil obtained through the hydrodistillation method. The main compounds were as follows : Ethylbis(trimethylsilyl)amine(1.04%), 2-(Trimethylsiloxy)benzoic methyl ester(2.65%), Hexadecanoic acid trimethylsilyl ester(12.61%), octadecanoic acid, trimethylsilyl ester(6.28%). Conclusions : The substances by hydrodistillation method may not perfectly match with the substances by supercritical fluid extraction(SFE) method in essential oils extracted form Rehmanniae Radix. But, the main substances was assumed Hexadecanoic acid and octadecanoic acid.

• 문화기술의 융합
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• 제8권6호
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• pp.615-624
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• 2022

본 연구는 자소자 열수추출물과 압력은 일정하게 유지한 상태로 온도를 조절하여 추출한 3종의 자소자 초임계추출물에 대해 항산화력, 항균활성, biofilm 형성 억제능과 염증매개물질(nitric oxide), 염증성 사이토카인(interleukin-6, interleukin-8)의 생성 억제능을 평가하였다. 자소자 열수추출물과 비교하였을 때 자소자 초임계추출물이 항산화 효과는 떨어졌으나, Staphylococcus aureus(S. aureus)에 대한 minimal inhibitory concentration(MIC)이 월등히 낮은 것으로 확인되었고, biofilm 형성 억제능 또한 더 우수하였다. 염증매개물질과 염증성 사이토카인의 생성도 자소자 초임계추출물이 자소자 열수추출물에 비해 현저히 감소시킬 수 있었다. 따라서 우리는 초임계추출물중 가장 우수한 항균작용과 biofilm 형성 억제, 염증인자 생성 억제 효능을 보인 45℃로 추출한 자소자 초임계추출물이 아토피 피부염 환자의 가려움증과 경표피수분손실을 방지하기 위한 천연 기능성 소재로 적합함을 시사한다.