• KSBB Journal
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• 제27권1호
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• pp.33-39
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• 2012

In this study three major curcuminoids in turmeric curcumin (1), demethoxycurcumin (2) and bismethoxycurcumin (3) were efficiently extracted by optimizing extraction condition and simultaneously identified using a fast and reliable RP-HPLC-UV-MS and TLC method. The analysis by the $C_{18}$ column was performed and the UV wavelength was fixed at 425 nm. In this result, the total extraction yield of turmeric (Curcuma longa) was increased with extraction time from 1 to 7 h. So, optimum extraction time is 4 h. Also, the highest yield of extraction amount 0.433g 8.66% was obtained by ultrasonic waves with quarter frequency kHz and an extraction time of 7 h. The experiment method was consistent with theoretical Value $r^2$ = 0.987 (1), 0.997 (2) and 0.998 (3). Moreover, LC-MS analysis provided efficiently molecular weight information of three major curcuminoids in turmeric extracts and high purity (~95%) of the curcuminoids were obtained. This work offers would be useful for chemical and biological studies of natural plants and its products.

• 한국식품영양과학회지
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• 제27권5호
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• pp.914-919
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• 1998

This work was designed to determine the optimum extraction conditions for imporving the quality of Eucommia ulmoidesl leaf-tea. Soluble solid content was 27.7% in the tea extracted at 99.3$^{\circ}C$(extraction temperature) and 67.8 min(extraction time) which were maximum points by the ridge analysis. The extraction conditions for the maximum organoleptic scores were 72.9$^{\circ}C$ and 59.6 min in color, 80.$0^{\circ}C$ and 90.0 min in aroma, 77.8$^{\circ}C$ and 55.5 min in aftertaste, and 77.9$^{\circ}C$ and 53.1 min in overall palatability. The extraction conditions for the minimum organoleptic scores were 77.8$^{\circ}C$ and 52.7 min in astringent taste, and 75.1$^{\circ}C$ and 49.4 min in Chinese medicine taste. The optimum ranges of the conditions based on soluble solid content and overall palatability of the tea wre 75~83$^{\circ}C$ and 55~65 min. The soluble solid content and overall palatability predicted at ooptimum condition(78$^{\circ}C$ and 60 min) werw similar to experimental values.

• 한국작물학회지
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• 제53권1호
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• pp.110-117
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• 2008

검정콩 품질평가의 한 기준이 되는 안토시아닌의 함량평가를 위한 분석기술 개발의 일환으로 검정콩 종피 함유 안토시아닌의 최적의 추출용매 및 추출방법을 확립하고, 주요재배 검정콩 종피 함유 안토시아닌의 함량을 정량적으로 평가한 결과를 요약하면 다음과 같다. 1. 검정콩 종피 함유 안토시아닌의 최적 추출용매를 검토한 결과 1% HCl - $H_2O$로부터 1% HCl - 80% MeOH용액까지 통계적 차이가 인정되지 않았으나, 산술적으로 1% HCl - 60% MeOH 용액으로 추출하였을 때 총 안토시아닌의 함량이 7.72 mg/g으로 가장 높은 양상을 나타내었으나, 추출용매에 메탄을 함량이 높아질수록 안토시아닌 피크의 분리도가 극히 불량한 결과를 나타내므로 종합적 견지에서 볼 때 1% HCl - 20% MeOH를 이용하여 안토시아닌을 추출하는 것이 가장 우수한 것으로 평가되었다. 2. 검정콩 종피 함유 안토시아닌의 최적 추출방법 및 추출시간을 검토한 결과 상온 12시간 추출이 가장 우수한 결과를 나타내었으며, 추출시간이 24시간 이상 지속될 경우 추출시간이 증대됨에 따라 안토시아닌의 함량이 소량 감소되는 양상을 확인할 수 있었다. 3. 국내외 주요 재배 검정콩 품종별 종피 함유 안토시아닌 색소의 함량을 비교한 결과 총 안토시아닌의 함량 범위는 1.58-10.62 mg/g으로 조사되었고, 조사된 품종 중 검정 올콩이 10.62 mg으로 가장 높은 양상을 나타내었으며, 가장 낮은 함량을 나타낸 흑청콩 대비 약 7배 높은 안토시아닌 함량을 나타내었다.

• 전력전자학회논문지
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• 제19권4호
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• pp.312-319
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• 2014

When distributed generation such as a wind power system is connected to the grid, it should meet grid requirements like IEEE Std. 1547, which regulates the anti-islanding method. Since the islanding may cause damage on electrical equipments or safety hazards for utility line worker, a distributed generation should detect it as soon as possible. This paper proposes a hybrid anti-islanding method coupled with the active and passive detection methods. To enhance the harmonic extraction capability for an active harmonic injection method, cascaded second-order band-pass filter and signal processing scheme are employed. Simulation and experiments are carried out under the islanding test condition specified in IEEE Std. 1547. Passive over/under voltage and over/under frequency methods are combined with the active method to improve the detection speed under certain condition. The simulation and experimental results are presented to verify that the proposed hybrid anti-islanding method can effectively detect the islanding.

• Natural Product Sciences
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• 제25권1호
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• pp.44-48
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• 2019

Nelumbo nucifera Gaertn. (Nymphaeaceae) is commonly called lotus and its leaves are widely been used as functional ingredients due to its antioxidant activity. For maximum efficacy, optimized extraction condition was established using response surface methodology. The high F-values, low p-values and insignificant p-value for lack-of-fit supported the fitness of the model and yielded the second-order polynomial regression for the antioxidant activity. The optimized extract was obtained by the extraction of 1 g of lotus leaves with 40 mL of 50% MeOH at $10.0^{\circ}C$, which exerted 70.1% antioxidant activity. Close correlation between phenolic content and antioxidant activity suggested phenolic compounds as active constituents of lotus leaves. In addition, comparison of different parts of lotus demonstrated the most potent antioxidant activity of flowers, followed by leaves and roots. Taken together, these results provide useful information about lotus leaves for the development as antioxidant ingredients. In addition, flowers and roots as well as leaves are suggested as good sources for antioxidant activity.

• Journal of Power Electronics
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• 제19권1호
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• pp.307-315
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• 2019

Condition monitoring has been recognized as an effective and low-cost method to enhance the reliability and improve the maintainability of power electronic converters. In power electronic converters, high-frequency oscillation occurs during the switching transients of power transistors, which is known as ringing. The ringing frequency mainly depends on the values of the parasitic capacitance and stray inductance in the oscillation loop. Although circuit stray inductance is an important factor that leads to the ringing, it does not change with transistor aging. A shift in either the inside inductance or junction capacitance is an important failure precursor for power transistors. Therefore, ringing frequency can be used to monitor the health of power transistors. However, the switching actions of power transistors usually result in a dynamic behavior that can generate oscillation signals mixed with background noise, which makes it hard to directly extract the ringing frequency. A frequency extraction method based on empirical mode decomposition (EMD) and Fast Fourier transformation (FFT) is proposed in this paper. The proposed method is simple and has a high precision. Simulation results are given to verify the ringing analysis and experimental results are given to verify the effectiveness of the proposed method.

• 한국응용과학기술학회지
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• 제41권2호
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• pp.520-529
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• 2024

Lycium barbarum extract has a high potential to be developed as a health functional food due to the various health-promoting effects of Lycium barbarum. This study analyzed changes in nutritional and functional components depending on the extraction solvent (purified water and a mixture of purified water and alcohol) and the condition of the sample. The nutritional components (carbohydrates, protein, fat, ash), organic acids, amino acids, total phenolic compounds, and total flavonoids of the extract produced during the extraction process were analyzed. The nutritional composition and functional substances of the extracts showed some differences depending on the type of solvent and the condition of the sample. The amounts of crude protein (7.61%), crude fat (1.63%), carbohydrate (90.22%), and ash (0.54%) of dried Lycium barbarum extract using purified water as a solvent were similar to those of the powder sample extract. The highest content of citric acid was 4.31 mg/mL, similar to the case of acetic acid, when the powder sample used a mixture of purified water and alcohol as a solvent. The highest amino acid content was 357.39 mg/mL when the powder sample was mixed with purified water and alcohol as a solvent. The total amount of phenolic compounds was 686.16 g/L when the powder sample was extracted with a mixture of purified water and alcohol as a solvent. The highest total flavonoid content was 111.32 g/L when the powder sample was extracted with a mixture of purified water and alcohol as a solvent.

• 자원리싸이클링
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• 제22권5호
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• pp.29-34
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• 2013

TEHA와TEHA 및TBP와 LIX63과의 혼합용매를 사용하여 염산용액으로부터 백금과 로듐을 분리하기 위한 용맥추출실험을 수행하였다. 염산농도 1-9 M 범위에서 추출제의 농도에 따른 두 금속의 추출거동과 분리 가능성을 조사하였다. 혼합용액에서 백금과 로듐의 농도는 각각 $1{\times}10^{-3}M$과 $2{\times}10^{-4}M$로 조절하였다. TEHA와 혼합추출제에 의한 추출시 로듐의 추출율은 추출조건에 의존하나, 백금은 염산농도와 무관하게 모두 추출되었다. 혼합용액에서 염산농도가 낮을 경우 로듐이 추출되지 않아 백금과 로듐의 분리가 가능하였다. LIX63을 첨가한 TEHA는 로듐의 추출율을 향상시켰으나, TBP를 첨가한 TEHA는 두 금속의 추출에 거의 영향을 미치지 않았다.

• 한국식품과학회지
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• 제37권2호
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• pp.178-182
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• 2005

본 연구에서는 올리브 잎의 적정 추출조건을 모색하고자 추출온도, 추출용매, 추출시간 등을 달리하여 올리브 잎 추출물들을 제조하였고 이들 추출물의 추출수율, 총 페놀 함량, 전자공여능 등을 비교, 분석하며 올리브 잎의 적정 추출조건을 조사하였다. 또한, 올리브 잎 추출물의 저장 안정성을 온도 및 pH 조건에서 검토하여 올리브 잎의 식품소재화를 위한 기초자료를 제공하고자 하였다. 추출조건에 따른 올리브 잎 추출물의 고형분 함량은 추출온도가 높아질수록, 추출하는 에탄올의 농도가 높을수록 올리브 잎 추출물들의 고형분 함량은 증가하는 경향을 보였다. 그러나 추출시간의 경우, 고형분 함량과 추출 시간과의 관계는 일정한 경향을 보이지 않았다. 고형분 함량이 가장 높게 나타난 조건은 $85^{\circ}C$, 80% 에탄올, 5시간 추출한 처리구(30%)이었다. 총 페놀 함량과 전자공여능은 추출용매의 에탄올 농도가 높아질수록 증가하는 경향을 보여 가장 많은 총 페놀 함량과 전자공여능을 나타낸 추출조건은 $25^{\circ}C$에서 80% 에탄올로 1시간 추출한 추출물이었으며 이때의 총 페놀 함량은 22.1%, 전자공여능은 70.5%이었다. $25,\;55,\;85^{\circ}C$에서 저장한 올리브 잎 추출물들은 저장기간이 길어짐에 따라 총 페놀 함량과 전자공여능 모두 소량의 감소치를 나타냈지만 올리브 잎 추출물에 함유된 페놀성 화합물들은 비교적 열에 안정하였다. 반면, pH의 경우, 산성과 중성 조건에서는 총 페놀 함량과 전자공여능 모두 증가하는 경향을 보였으나 약알칼리(pH 10) 조건에서는 약간의 감소치를, 강알칼리(pH 14) 조건에서는 급격한 감소치를 보였다. 결론적으로 기능성 식품소재로 올리브 잎 추출물을 제조시 추출용매로는 80% 에탄올을, 추출시간은 1시간 내외로 저온에서 추출하는 것이 바람직하며 올리브 잎 추출물을 저장시 산성 또는 중성 조건에서 저장하는 것이 적절한 것으로 나타났다.

• Applied Biological Chemistry
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• 제40권4호
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• pp.267-270
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• 1997

쑥으로부터 Clostridium perfringens의 생육 저해 물질의 추출 조건을 조사하였다. 쑥의 유용성분을 최대한 추출하기 위하여 C. perfringens에 대한 생육 억제 정도를 기준으로 추출용매 농도, 추출온도 및 추출시간을 조사한 결과 100% ethanol, $40^{\circ}C$, 4시간 추출한 것이 C. perfringens의 생육 저해에 효과가 가장 좋았다.