• Food Engineering Progress
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• v.14 no.2
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• pp.166-172
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• 2010

The extraction of polyphenol and flavonoid from citrus peel was performed by the ethanol, sugar, hot water (80$^{\circ}C$), and subcritical water extraction methods. The maximum yields of total polyphenolic compounds (27.25${\pm}$1.33 mg QE/g DCP, QE and DCP indicate quercetin equivalent and dried citrus peel, respectively) and flavonoids (7.31${\pm}$0.41 mg QE/g DCP) were obtained by subcritical water extraction (SWE) with operating conditions of 190$^{\circ}C$, 1300 psi, and 10 min. The yields by SWE were over 7.2-, and 8.5-fold higher than those of total polyphenols (3.79${\pm}$0.73 mg QE/g DCP) and flavonoids (0.86${\pm}$0.27 mg QE/g DCP) obtained using the ethanol extraction, which showed the highest extraction efficiency among tested conventional methods, respectively. Antioxidant activities of extracts obtained by different methods showed no significant differences. However, the relative antioxidant yield per 1 g dried citrus peel by SWE (190$^{\circ}C$, 10 min) was over 9.5-fold higher than that by the ethanol extraction.

• Food Engineering Progress
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• v.14 no.4
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• pp.335-341
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• 2010

The extraction of polyphenol and flavonoid from black rice bran was performed by diverse extraction methods using the sugar solution, ethanol, hot water ($80^{\circ}C$), and by subcritical water extraction (SWE) method. By SWE under operating conditions of $190^{\circ}C$, 1,300 psi, and 10 min, the maximum yields of total polyphenolic compounds (35.06${\pm}$1.28 mg quercetin equivalent (QE)/g dried material and flavonoids (7.08${\pm}$0.31 mg QE/g dried material) could be obtained. These results were over 11.77- and 12.21-fold higher than those of the ethanol extraction, which showed the highest extraction efficiency among tested conventional methods in total polyphenols (2.98${\pm}$0.74 mg QE/g dried material) and flavonoids (0.58${\pm}$0.21 mg QE/g dried material), respectively. Though the highest antioxidant activity (87.14${\pm}$1.14%) was observed at the dried extract obtained from ethanol method, the relative antioxidant activity per 1 g dried black rice bran by SWE ($190^{\circ}C$, 10 min) was over 11.53-fold higher than that by the ethanol extraction.

• Elastomers and Composites
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• v.34 no.3
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• pp.239-246
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• 1999

Side wall samples from a used automotive tire were subjected to subcritical and supercritical decomposition and extraction with three solvents, water, 28% ammonia solution and ammonia. For 6mm cube samples the rate of supercritical extraction with water followed a first-order kinetics with an activation energy of 140 kJ/mol. Solvent power of 28% ammonia so lotion at supercritical condition was found to be higher than supercritical water at initial extraction as pressure decreased. These phenomena were considered to be an effect of ammonia involved in water.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10b
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• pp.55-57
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• 2003

XML은 W3C에서 웹 문서의 표준으로 제안한 마크업 언어로, 인터넷상에서 데이터를 표현하고 교환하는데 사용되고, 이를 DBMS에 저장하고 관리하려는 연구가 많이 진행되었다. 현재에는 관계형 데이터 모델, 객체지향형 데이터 모델. 그리고 객체관계형 데이터 모델 등 다양한 데이터 모델에서 XML 문서를 관리할 수 있다. 하지만 DBMS가 아무리 뛰어난 기능을 발휘한다하더라도 해당 XML 문서의 구조와 맞지 않는 구조를 가지고 있다면, XML 문서는 효율적으로 관리될 수 없다. 따라서 XML 문서를 DBMS에 저장하기 전에, 그 XML 문서를 어떤 데이터 모델에 저장하는 것이 효율적인지를 미리 판단할 수 있다면 매우 바람직한 일일 것이다. 본 논문에서는 저장 임계점을 사용하여, 일반적인 XML 문서를 어떤 데이터 모델을 사용하여 저장하는 것이 효율적인지를 제시하고자 한다.

• Journal of the Korea Concrete Institute
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• v.19 no.3
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• pp.367-375
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• 2007

Critical chloride content for corrosion initiation is a crucial parameter in determining the durability and integrity of reinforced concrete structures, however, the value is still ambiguous. Most of the studies reporting critical threshold chloride content have involved the experimental measurement of the average amount of the total chloride content at arbitrary time. The majority of these researches have not dealt with this issue combined with carbonation of concrete, although carbonation can significantly impact on critical threshold chloride content. Furthermore, the studies have tried to define the critical chloride content within the scope of their experimental concrete mix proportion at arbitrary time. However, critical chloride content for corrosion initiation is known to be affected by a lot of factors including cement content, type of binder, chloride binding, concentration of hydroxyl ions, and so on. It is necessary to define the unified formulation to express the critical chloride content for various mix proportions of concrete. The purpose of this study is to establish an analytical formulation of the critical chloride content of concrete. In this formulation, affecting factors, such as mix proportion, environment, chemical evolution of pore solution with elapsed time, carbonation of concrete and so on are taken into account. Based on the Gouda's experimental results, critical chloride content is defined as a function of $[Cl^-]$ vs. $[OH^-]$ in pore solution. This is expressed as free chloride content with mass unit to consider time evolution of $[OH^-]$ content in pore solution using the numerical simulation programme of cementitious materials, HYMOSTRUC. The result was compared with other experimental studies and various codes. It is believed that the approach suggested in this study can provide a good solution to determine the reasonable critical chloride content with original source of chloride ions, for example, marine sand at initial time, and sea water penetration later on.

• Food Engineering Progress
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• v.22 no.4
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• pp.304-308
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• 2018

The interest in and development of healthy foods and nutraceuticals have increased because of the trend for a health-oriented society. Cinnamon is used as a food ingredient as well as a herbal medicine because of its functional properties. In this study, flavoring compounds and antioxidative activities of cinnamon extracts were investigated with different extraction solvents and extraction methods. The contents of flavoring compounds such as coumarin, cinnamic acid, cinnamaldehyde, and cinnamyl alcohol were investigated. The contents of courmarin, cinnamic acid, and cinnamylaldehyde in 70% ethanol extract were higher than those in hot water and subcritical water extracts. The contents of courmarin, cinnamic acid, and cinnamaldehyde in subcritical water extract were higher than those in hot water extract, whereas the content of cinnamyl alcohol was lower. DPPH scavenging activity increased with increasing concentration of the extracts, and the 70% ethanol extract showed the highest antioxidant activity. The ascorbic acid content of the 70% ethanol extract was largest in the antioxidative activity measurement by FRAP analysis. The ascorbic acid contents of the hot water and subcritical water extracts were similar.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.3
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• pp.277-284
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• 1986

A numerical procedure (integral method) for calculating the interacting turbulent boundary layer is set up. With this method, some free interactions with various upstream conditions are simulated in order to investigate the influence of upstream state on the interacting turbulent boundary layer. The results obtained by this numerical simulation can be summarized as follows; Free interaction of upstream unstabilized (or separated) turbulent boundary layer is subcritical regardless of its external Mach number, while free interaction of upstream stabilized turbulent boundary layer has two different characteristics (subcritical, supercritical) according to the external Mach number.

• Proceeding of EDISON Challenge
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• 2012.04a
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• pp.77-80
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• 2012

초음속 흡입구는 설계점에서 안정적으로 작동하지만 설계점 밖에서는 엔진성능이 급격히 감소하거나 층 격파 불안정 문제가 발생할 수 있다. 초음속 흡입구의 일반적인 특성을 파악하기 위해 2단 꺾임각을 갖는 외부 압축식 2차원 흡입구를 설계하고 EDISON_열유체 시스템을 이용하여 최종적으로 설계 마하수 2.5에서 작동하는 형상을 얻었다. 그러나 설계 마하수 이하의 영역에서는 충격파-경계층, 충격파간 상호작용으로 인해 유동에서 박리가 발생하고 최종적으로 흡입구 목을 질식시켜 아임계 상태로 천이된다. 이를 해결하기 위해 유동 제어 방법 중 하나인 bleeding을 이용하여 경계층을 제거하거나 유동의 박리를 방지하여 충격파를 cowl lip 전방에 안정하게 고정시킬 수 있었으며, 결과적으로 목적하였던 마하수 2.0에서 2.5에 이르는 작동 영역에서 강건하게 운용될 수 있는 초음속 흡입구를 설계하였다.

• Journal of Power System Engineering
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• v.5 no.1
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• pp.11-20
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• 2001

Super-critical type steam power plant, which operates with steam pressure above the super-critical point, has a good reputation recently and is adopted as a new standard of the Korean Electric Power Corporation. The reason for the good reputation lies in it's superior power efficiency. However, the field data of the new power plant for the verification of it's performance are still insufficient, and more empirical data are needed to acquire technologies on the effective operation of it. In this study, the authors analyzed the field test data on power efficiencies got in a super-critical type steam power plant, and evaluated the excellency of the new plant by comparing the efficiency data with the one got in a conventional sub-critical type steam power plant.

• Applied Chemistry for Engineering
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• v.17 no.3
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• pp.291-295
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• 2006

The keto-enol tautomeric equilibrium constant, K, of ethyl acetoacetate in compressed and supercritical carbon dioxide was determined by using FT-IR (Fourier transform infrared) spectroscopy at three different temperatures. In order to investigate the effect of solvent density, the $CO_{2}$ pressure was systematically changed at a constant temperature. As the $CO_{2}$ density is increased, the amount of keto tautomer is increased, causing the K value to decrease. The modified lattice fluid hydrogen bonding theory has been applied to investigate the effect of density on the K.