• 마이크로전자및패키징학회지
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• 제25권3호
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• pp.1-5
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• 2018

본 연구에서는 InGaN/GaN multi quantum well (MQW)에서 Indium (In) 도핑효과에 따른 광전기화학적 특성을 관찰하였다. 기판으로는 Sapphire을 사용하였고, 각 Quantum well (QW)을 구성하고 있는 InGaN의 조성을 다르게 하였다. 투과도 측정 결과 일정한 In 조성을 가진 InGaN/GaN MQW에 비해 각 QW의 In 조성을 다르게 한 InGaN/GaN MQW에서 흡수도가 향상되는 것을 확인할 수 있었다. 이는 각각 다른 In 조성을 가진 InGaN 층이 더 넓은 영역의 스펙트럼 에너지를 가지는 빛을 흡수하기 때문인 것으로 생각된다. 광학적 특성을 평가하기 위해 진행한 상온 photoluminescence (PL) 실험을 진행한 결과, 역시 다양한 In 조성을 가진 InGaN/GaN MQW이 더 넓은 파장에서 발광이 나타나는 것을 확인할 수 있었다. 이들 샘플에 대한 광전기화학적 특성평가를 통하여, gradation In 조성을 가지고 있는 InGaN/GaN MQW이 일정한 In 조성을 가지는 InGaN/GaN MQW에 비해 광전기화학적 물분해 능력이 월등히 향상됨을 확인하였다.

• 한국식품조리과학회지
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• 제29권5호
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• pp.453-462
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• 2013

Recently, two formulas of sulgidduk added to pine needle juice (PNJ) with various physiological activities were developed for metabolic syndrome patients in our lab. According to previous studies, cooking may alter antioxidant properties by initiating destruction, release or transformation of antioxidant compounds contained in food. Therefore, the aim of this study was to compare the antioxidant activities and antigenotixic effects of sulgidduk with/without PNJ and to note changes in these activities after cooking. The ingredients of sulgidduk was added on the basis of 100% rice flour as follows: conventional sulgidduk (S): 1.5% salt, 30.0% sugar; PNJ added to sulgidduk A (PS-A): 1.4% salt, 30.0% sugar, and 1.0% PNJ; PNJ added to sulgidduk B (PS-B): 1.5% salt, 21.4% sugar, and 1.4% PNJ. Ethanol and water extracts of sulgidduk were analyzed for the total phenolic content (TPC), DPPH radical scavenging activity (DPPH RSA), total radical-trapping antioxidant potential (TRAP), oxygen radical absorbance capacity (ORAC), and antigenotoxic effect by comet assay. The ethanol extracts PS-A and PS-B showed higher TPC and antioxidant activities (DPPH RSA, TRAP, and ORAC) than did the S ethanol extract before cooking. The more PNJ was added, the higher TPC and anitoxidant activities were observed in sulgidduk (PS-A$200{\mu}M$ of $H_2O_2$. Taken together, this study suggests that sulgidduk added to 1.44% of pine needle juice may be a good option antioxidant and antigenotoxic source.

• Journal of Biosystems Engineering
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• 제33권6호
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• pp.430-437
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• 2008

Optical diffuse reflectance sensing in visible and near-infrared wavelength ranges is one approach to rapidly quantify soil properties for site-specific management. The objectives of this study were to investigate effects of preprocessing of reflectance data and determine the accuracy of the reflectance approach for estimating physical and chemical properties of selected Missouri and Illinois, USA surface soils encompassing a wide range of soil types and textures. Diffuse reflectance spectra of air-dried, sieved samples were obtained in the laboratory. Calibrations relating spectra to soil properties determined by standard methods were developed using partial least squares (PLS) regression. The best data preprocessing, consisting of absorbance transformation and mean centering, reduced estimation errors by up to 20% compared to raw reflectance data. Good estimates ($R^2=0.83$ to 0.92) were obtained using spectral data for soil texture fractions, organic matter, and CEC. Estimates of pH, P, and K were not good ($R^2$ < 0.7), and other approaches to estimating these soil chemical properties should be investigated. Overall, the ability of diffuse reflectance spectroscopy to accurately estimate multiple soil properties across a wide range of soils makes it a good candidate technology for providing at least a portion of the data needed in site-specific management of agriculture.

• Restorative Dentistry and Endodontics
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• 제38권1호
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• pp.36-42
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• 2013

Objectives: This study evaluated the antibacterial effect and mechanical properties of composite resins ($L_{CR}$, $M_{CR}$, $H_{CR}$) incorporating chitosan with three different molecular weights (L, Low; M, Medium; H, High). Materials and Methods: Streptococcus (S). mutans 100 mL and each chitosan powder were inoculated in sterilized 10 mL Brain-Heart Infusion (BHI) solution, and was centrifuged for 12 hr. Absorbance of the supernatent was measured at $OD_{660}$ to estimate the antibacterial activities of chitosan. After S. mutans was inoculated in the disc shaped chitosan-containing composite resins, the disc was cleansed with BHI and diluted with serial dilution method. S. mutans was spread on Mitis-salivarius bacitracin agar. After then, colony forming unit (CFU) was measured to verify the inhibitory effect on S. mutans biofilm. To ascertain the effect on the mechanical properties of composite resin, 3-point bending and Vickers hardness tests were done after 1 and 3 wk water storage, respectively. Using 2-way analysis of variance (ANOVA) and Scheffe test, statistical analysis was done with 95% significance level. Results: All chitosan powder showed inhibition effect against S. mutans. CFU number in chitosan-containing composite resins was smaller than that of control resin without chitosan. The chitosan containing composite resins did not show any significant difference in flexural strength and Vickers hardness in comparison with the control resin. However, the composite resin, $M_{CR}$ showed a slightly decreased flexural strength and the maximum load than those of control and the other composite resins $H_{CR}$ and $L_{CR}$. Conclusions: $L_{CR}$ and $H_{CR}$ would be recommended as a feasible antibacterial restorative due to its antibacterial nature and mechanical properties.

• 한국식품과학회지
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• 제44권5호
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• pp.643-647
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• 2012

The antioxidant capacity of aloe vera gel (AG), aloe vera exudates (AE), and a low molecular filtrate of aloe vera gel (ALMF) prepared from aloe vera grown on Jeju Island, Korea was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis-3-ethyl-benzothiazoline-6-sulfonic acid (ABTS), and oxygen radical absorbance capacity (ORAC) assays, and total phenolic content (TPC), and total flavonoid content (TFC) were determined. The phenolic compounds in aloe samples were analyzed. Antioxidant capacities in oil-in-water emulsions following riboflavin photosensitization were analyzed using lipid hydroperoxide. AE had significantly higher antioxidant capacity than that of the other samples based on the DPPH, ABTS, and ORAC assays (p<0.05). Lipid hydroperoxide values of 5 mg/mL for AG, AE, and ALMF were 521.78, 272.32, and 699.89 mmol/kg oil, respectively, whereas that of samples without aloe vera was 893.07 mmol/kg oil over 48 h. AE had higher TPC and TFC values. Aloesin and aloin were found in AE, whereas those compounds were only found in trace amounts in AG and ALMF.

• Korean Chemical Engineering Research
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• 제52권6호
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• pp.701-705
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• 2014

본 연구에서는 꾸지뽕나무의 뿌리, 줄기, 열매 및 잎으로부터 유효성분을 열수 추출하고 다양한 화장품 소재 시험을 실시하여 화장품 소재로서의 개발 가능성을 검토하였다. 세포독성시험에서 꾸지뽕나무의 뿌리, 줄기 그리고 열매 추출물은 독성을 나타내지 않았지만 잎 추출물은 $200{\mu}g/ml$ 이상의 농도에서 다소의 독성을 나타내었다. 꾸지뽕나무 뿌리추출물은 $500{\mu}g/ml$의 농도에서 81%의 tyrosinase 억제효과(미백효과)와 58%의 elastase 억제효과(주름개선효과)를 나타내었고, UVB 자외선 흡수능도 다소 보여주었다. 21일간의 온도 안정성 시험 결과, 꾸지뽕 뿌리 추출물을 포함한 액제와 로션제형은 $25^{\circ}C$에서는 안정하였으나 $47^{\circ}C$에서 점도와 입자크기가 불안정하였다. 본 연구 결과 꾸지뽕 뿌리추출물은 높은 폴리페놀 및 플라보노이드의 함량, 우수한 미백 및 주름개선 효과를 나타내어 천연 기능성 화장품 소재로서 높은 가능성을 보여주었다.

• 복식
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• 제39권
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• pp.79-89
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• 1998

This study was carried out the effect of stability and color extract for it's condition in the curcuma L.. dyeing. The stability is to investigate the absorbance of the curcumin, one of the major yellow pigments and the stability regarding the effect of light, oxygen temperature and pH. The dyeing condition is compared the effect of mordanting condition and the best way to extract pigment and analysed through the color-fastness rating, color-difference value test. The main results obtained are summarized as follows ; 1.The best and proper solvent to extrect curcumin pigment was a ethanol and a distilled water. 2. The light effect indicated that the absorbances of solution in absence of ligh was more stable. 3. The oxygen(O2) effect to curcumin show-ed that the condition in the absence of O2 was more stable than that in presence of O2 4. The temperature showed that the absorbnace was best stable in4$^{\circ}C$ and less changed at $25^{\circ}C$ 5. The curcumin-etanol solution was stable in pH 2~4. 6. Generally color-fastness rating to silk, wool and cotton indicated that crocking C.F. and perspiration C.F. were more than 3rd grade and dry cleaning C.F. was more than 4th grade. But light color-fastness and washing color-fastness were very poor. 7. To make good color fastness, the mordan-ting treated group and the pre-mordant conditions were more effective than others 8. When compared with color-difference value test indicated that the silk was looks like more reddish and bluish color and than the wool and cotton were greenish and bluish. As a mordant, A(C2H4OH(COOH3) and D(K2Cr2O7)were more effective to make green-ish color in the silk and the reddish color was abtained by B(Al.K(SO4)2.12H2O) and C(FeSO4.7H2O).

• Carbon letters
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• 제10권1호
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• pp.14-18
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• 2009

We measured the degree of macrodispersion of the various single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) using UV-VIS-NIR absorption spectroscopy. CNTs were dispersed with SDS of 2 wt % in deionized water using the homogenizer and then were further centrifugated at 6000 g for 10 min. The degree of macrodispersion, expressed by $D_m({\lambda})=A_a({\lambda})/A_b({\lambda})^*100$ (%), where ${\lambda}$ is the wavelength and $A_a({\lambda})$ and $A_b({\lambda})$ are the absorbance of the sample after and before centrifugation, respectively. In the case of MWCNTs, we evaluated the degree of macrodispersion by the average degree of macrodispersion ($D_m({\lambda})$) between 1000 and 1200 nm. The degree of macrodispersion of SWCNTs was evaluated at the wavelength in which van Hove singularity-related transition regions were excluded, i.e., the range was chosen between ${E_{11}}^S$ and ${E_{22}}^S$ peaks. We have estimated six samples with the same method. The standard deviation of each sample was lower than 5. Therefore, we presented a reliable evaluation method for the macrodispersion of CNTs for standardization.

• 한국식품영양과학회지
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• 제23권6호
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• pp.1032-1037
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• 1994

A simple, reproducible , and accurate enzymatic method using a cholesterol assay kit was developed to quantify total cholesterol content in egg yolk. Total egg yolk lipid was extracted with hexane : isopropanol(3 : 2, v/v) mixture. Samples containing various amount of the total lipid(0-3mg) in optically identifical culture tubes were reacted for 10 min in a water bath (37$^{\circ}C$) with the enzyme solution (5ml) from the cholesterol assay kit. Cholesterol content of the reaction mixturesin culture tubes was spectrophotometrically determined by two different ways : (1) using the culture tube as a curvette(designate culture tube method ; CTM) and (2) the quartz cvette containing the reaction mixture transferred from the culture tube (designate standard cvette method, SCM). CTM revealed lower cholesterol content in 0.1-1.0mg lipid sample range that SCM did, but not significant. For more than 2.0mg lipid sample, CTM gave significantly (p<0.01) lower cholesterol content relative to that by SCM, suggesting that SCM give a false positive result from the sample containing more than 2 mg lipid due to the interference of absorbance by lipid dispersed in the reaction solution . Cholesterol content of less than 1.0mg lipid sample by CTM was proportional to the amount of lipid used, but its linear relationship was not seen in more than 2mg lipid sample. Thus, to determine the appropriate lipid amounts (mg) analyzed . A constant level (41$\mu\textrm{g}$/mg) of cholesterol concentration was observed from the sample containing 0.1-1mg lipid. after which the cholesterol level was dropped to less than 41$\mu\textrm{g}$ /mg. Cholesterol concentration in egg yolk samples quantified by CTM was in accordance with that by GC method. These results suggest that CTM is an useful method for the quantification of cholesterol in egg yolk lipid and other lipids as well.

• 공업화학
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• 제2권3호
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• pp.262-269
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• 1991

${\beta}$-carotene의 오존산화반응을 통하여 불포화 색소물질에 대한 오존의 탈색효과와 반응성분의 변화를 정량적으로 비교하였으며, 카로티노이드계 색소가 주요 발색원인물질인 beeswax 에 대한 오존의 산화반응을 물, 0.5%와 1.0% 수산화나트륨수용액, 20% 와 95% 초산수용액에서 실시하여 각 반응계에 따른 탈색효과를 비교검토하였고, 과산화수소의 첨가효과도 검토하였다. ${\beta}$-carotene의 불포화이중결합의 감소와 탈색효과는 정량적으로 비례하였으며 beeswax의 탈색효과도 잘 일치하는 결과를 얻었다. Beeswax의 탈색효과는 1.0 % 수산화나트륨수용액에서 반응한 것이 가장 우수하였으며. 과산화수소의 첨가(왁스의 2%)시 390 nm 에서의 흡광도가 0.045 로 좋은 탈색효과를 얻을 수 있었다. Beeswax의 탈색에 있어 오존산화반응이 물리흡착보다 효과적이라는 결론을 얻을 수 있었다.