• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.33-38
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• 2010

A microfluidic system has been developed using biomaterial for the measurement of cupric ion concentration. The cell-membrane-mimicking bilayer lipid membrane(BLM)-coated silver electrode was used for the sensing of cupric ion concentration. The silver-supported BLM could increase its stability. A silver-supported bilayer lipid membrane(s-BLM) was easily obtained using its self-assembling characteristics by immersing silver wire into lipid(phosphatidylcholine; PC) solution and then dipping into aqueous KCl solution. These s-BLMs were used to determine the relationship between $Cu^{2+}$ concentration and current crossing s-BLM. Their relationship showed high linearity and reproducibility. The calibration curve was constructed to express the relationship between $Cu^{2+}$ concentration and current in the $Cu^{2+}$ concentration range of 10 and $130{\mu}M$. This calibration curve was used to measure $Cu^{2+}$ concentration in an unknown sample. Microfluidic system with s-BLM was made of PDMS(polydimethyl siloxane) using typical soft photolithography and molding technique. This integrated system has various functions such as activation of the silver surface without cutting silver wire, coating of BLM on silver surface, injection of KCl buffer solution, injection of $Cu^{2+}$ sample and measurement of $Cu^{2+}$ concentration in the sample.

• Korean Journal of Veterinary Research
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• v.35 no.4
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• pp.833-841
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• 1995

Ultrasonography was used to measure the corpus luteum area for determining the relationships between corpus luteum size and milk progesterone concentration during the estrous cycle in 16 dairy cows. Cows were classified retrospectively into cows that had corpus luteum with(n=P) and without(n=7) cavity. Ultrasound examination and collection of milk samples for progesterone assay were performed with 2 day intervals from Days 0 to 12, and then daily from Day 14 to the day of the next ovulation. The means for corpus luteum area and for milk progesterone concentration during the estrous cycle were not significantly different between cows that had corpus luteum with and without cavity. The correlation coefficients between corpus luteum area and milk progesterone concentration during luteal development (Days 2 to 8) were 0.71(p<0.0001) and 0.74(p<0.0001) for corpus luteum with and without cavity, respectively, during luteal regression(Days -6 to 0 relative to the next ovulation) 0.73(p<0.0001) and 0.76(p<0.0001), respectively. The correlation coefficients combined fur both stages of estrous cycle and both luteal statuses were 0.70(p<0.0001). These results indicate that corpus luteum area is significantly correlated to milk progesterone concentration, and ultrasonographic assessment of the corpus luteum is a reliable method fur estimating peripheral progesterone concentrations during the estrous cycle in cows.

• Journal of Preventive Medicine and Public Health
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• v.33 no.2
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• pp.193-198
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• 2000

Objective : To evaluate the relationship between serum leptin concentration and obesity indices in a rural population. Methods : Two hundred and nine subjects were randomly sampled from 1036 residents who had participated in the survey. Their obesity indices were measured by bioelectrical impedance analysis and anthropometry. Serum leptin concentrations were measured by immunoradiometric assay. Results : Serum leptin concentrations were positively correlated with body mass index, percent of body fat, fat mass, waist circumference, and hip circumference. Serum leptin concentrations were higher in obese or overweighted subjects than normal or thin subjects(8.5[0.9-31.4] compared with $2.7[0.1-12.0]{\mu}g/L$, p<0.01). Serum leptin concentrations were higher in women than men, even after an adjustment to body mass index$(\beta=4.183,\;p<0.01)$. According to body composition, serum leptin concentrations were more related with waist circumference in men, hip circumference in women. Conclusions : Serum leptin concentrations are positively correlated with obesity indices. Serum leptin concentrations are higher in obese subjects, in women, and more related with peripheral obesity. These findings support the hypothesis that human obesity is associated with leptin-resistance rather than leptin-deficiency.

• Microbiology and Biotechnology Letters
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• v.49 no.4
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• pp.485-492
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• 2021

In this study, the whitening effect of Abelmoschus esculentus extract was investigated to confirm its applicability in cosmetics. To determine the whitening effect, the tyrosinase-inhibitory activity of Abelmoschus esculentus hot water extract (AEWE) and 70% ethanol extract (AEEE) was measured. At the final concentration of 1000 ㎍/ml, AEWE showed an inhibitory activity of 22.2% and AEEE of 32.8%. To determine the whitening effect at the cellular level, the viability of melanoma cells treated with AEWE and AEEE was evaluated using the MTT assay. At concentrations of 100 ㎍/ml or less, both AEWE- and AEEE-treated groups showed cell survival rates of >95%. Furthermore, in both AEWE- and AEEE-treated melanoma cells, the melanin content decreased in a concentration-dependent manner. The inhibitory effects of AEWE and AEEE used at 5, 10, 50, and 100 ㎍/ml on protein expression were measured by western blot, with β-actin as the positive control. At a concentration of 100 ㎍/ml, AEWE showed an inhibitory effect of 88.1%, 24.8%, 62.2%, and 42.9% on microphthalmia-associated transcription factors (MITF), tyrosinase, tyrosinase-related proteins (TRP)-1, and TRP-2 factors, respectively. At the same concentration, AEEE showed inhibitory effect of 65.3%, 58.3%, 66.2%, and 65.3% against MITF, tyrosinase, TRP-1, and TRP-2 factors, respectively. In conclusion, the whitening effects of AEWE and AEEE were verified, and their applicability as a natural ingredient in cosmetics was confirmed.

• Journal of Life Science
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• v.34 no.2
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• pp.105-112
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• 2024

In this study, the various whitening activities of Inonotus obliquus were assessed for potential use as functional cosmetic materials. When measuring electron donating ability to confirm the antioxidant ability of I. obliquus extract, increased activity was observed as the concentration increased, and it was found an outstanding antioxidant capacity of 82.1% at a 1,000 ㎍/ml concentration. Also, the tyrosinase inhibitory effect, related to a whitening effect, was found to have inhibitory activity that increased in a concentration-dependent manner. The results of verifying the viability of melanoma cells (B16F10) using an MTT assay showed cell viability of more than 80% at concentrations below 100 ㎍/ml. Therefore, cell-related experiments were conducted at 25, 50, and 100 ㎍/ml concentrations. By measuring protein expression related to melanin synthesis via treating B16F10 cells with I. obliquus extract, it was confirmed that protein expression was inhibited in all factors, depending on the concentration. TRP-1 and MITF appeared by 40.1% and 64.2% amount of expression, respectively, at 100 ㎍/ml concentrations, and tyrosinase and TRP-2 were verified as having better protein expression inhibition than arbutin. In measuring mRNA expression related to melanin synthesis by treating B16F10 cells with I. obliquus extract, it was confirmed that mRNA expression was suppressed as the concentration increased. Accordingly, it was confirmed that I. obliquus extract has excellent whitening activity and could be used as a cosmetic material.

• Journal of Applied Biological Chemistry
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• v.60 no.2
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• pp.101-108
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• 2017

The phenolic contents which were extracted with water and 70% ethanol from O. undulatifolius were 7.7, 10.1 mg/g, respectively. The 1,1-diphenyl-2-picrylhydrazyl free radical scavenging activity of water and ethanol extracts were 78, 82% at $50{\mu}g/mL$ phenolics, respectively. The 2,2'-Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation decolorization activity were 92, 76% at $100{\mu}g/mL$ phenolics. Antioxidant protection factor in water and ethanol extracts at $200{\mu}g/mL$ phenolics were 1.51 and 2.08 PF, respectively. Thiobarbituric acid reactive substance were 84% in water extracts and 99% in ethanol extracts at $50{\mu}g/mL$ phenolics, respectively. The inhibition activity on ${\alpha}-Glucosidase$ was 44% in ethanol extracts at $200{\mu}g/mL$ phenolics. The inhibition activity on ${\alpha}-amylase$ was 37-88% in water extracts at $50-200{\mu}g/mL$ phenolics. The tyrosinase inhibition activity as whitening effect were 82% in ethanol extracts. The elastase inhibition activity were 4, 61% in water and ethanol extracts, respectively. The collagenase inhibition activity of antiwrinkle effect showed an excellent wrinkle improvement effect as 39% in water extracts and 67% in ethanol extracts at $200{\mu}g/mL$ phenolics, respectively. The hyaluronidase inhibition activity as anti-inflammation effect of ethanol extracts was confirmed to 46% of inhibition at $200{\mu}g/mL$ phenolic. The astringent effect of water and ethanol extracts was confirmed to 13, 32% of effect at $200{\mu}g/mL$ phenolic, respectively.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.127-128
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• 2008

본 연구에서는 비분산 적외선 방식을 이용한 일산화탄소, 이산화탄소 듀얼 센서 모듈을 실현한다. 비분산 적외건 방식은 가스분자가 특정 파장의 적외선을 흡수하는 특성을 이용하여 가스의 적외선 흡수도를 측정하여 농도로 환산하는 방식이다. 비분산 적외선 방식은 수명이 길고 정밀도가 높아 기존의 접촉식(화학식) 센서에 비해 우수한 특성을 가지고 있다. 중요한 기술은 NDIR의 핵심부분인 광 공동의 설계 기술과 센서의 성능을 최종 결정짓는 농도-온도 교정 기술이다. 현재까지 개발된 광공동 기술은 $CO_2$ 센서의 단일 센서 방식이었다. 본 연구에서는 이 기술을 접목한 일산화탄소까지 동시에 측정할 수 있는 광 공동기술과 교정기술을 연구개발하여 하나의 광 공동으로 이산화탄소와 일산화탄소를 동시에 측정 할 수 있는 고기능 센서를 실현하는 것이다.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1911-1913
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• 2001

전위차 측정형 바이오 센서는 기준전극에 대한 센서 전극의 전기화학적 전위를 정확하게 측정하여야 하므로 기준전극의 안정성이 매우 중요하다. 기준전극의 전위는 전해질 용액 내의 염소 음이온 농도에 영향을 받으나 다행히도 혈액 내의 염소 음이온 농도는 거의 변화가 없으므로 혈액 속에서의 은/염화은 기준전극의 전위도 거의 변화가 없다. 본 연구에서는, 사진석판 (Photolithography) 공정을 이용하여 실리콘 표면 및 다공질 실리콘 표면에 은/염화은 박막 기준전극을 제작하고 시료 용액에서의 drift, 안정성, 재현성 등에 대한 특성을 고찰하였고, SEM, AES, EDX 스펙트럼 등을 이용하여 전극의 표면을 분석하였다. 시료 용액의 염소 음이온 농도를 $10^{-4}$M에서 1M까지 변화시켜가며 기준 전극의 전위를 측정한 결과 약 50mV/pCl의 기울기를 얻었으며 이것은 Nernst식을 잘 따르는 결과이다.

• Korean Journal of Environmental Agriculture
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• v.19 no.2
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• pp.188-190
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• 2000

We explored changes in soil nitrogen (N) availability in a thinned (control, light, moderate, and heavy thinning) Larix leptolepis plantation determined by using ion exchange resin bags. Nitrogen availability varied among measurement periods, however, total available N (ammonium plus nitrate) concentrations did not change significantly in the 1 year since thinning. We found higher N availability in summer and fall than in winter.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2006.11a
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• pp.117-118
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• 2006

본 연구에서는 2001년부터 2005년까지의 최근 5년간의 대구시 보건환경연구원의 대기질 자동측정망 자료와 대구기상대의 기상자료를 이용하여 다중회귀분석을 통하여 대구시 주거 지역의 오존농도를 예측하였다. 대구시 주거지역의 고농도 오존은 측정소별로 대명동은 총 327회 중 153회(46.79%), 신암동은 총 310회 중 143회(46.13%), 만촌동은 총 262회 중 140회(53.44%)로 기온과 일사량이 증가하는 5, 6월에 주로 많이 발생하였다. 다중회귀분석 결과 각 측정소별로 수정된 $R^2$는 각각 0.611, 0.655, 0.624으로 양호한 회귀 모형을 나타내었다.