• Transactions on Electrical and Electronic Materials
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• 제10권6호
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• pp.217-221
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• 2009

The use of the carbon nanotube (CNT) is superior to the general powder state materials in their thermal and chemical properties. Because its ratio of diameter to length (aspect ratio) is very large, it is known to be a type of ideal nano-reinforcement material. Based on this advantage, the existing carbon black of the semiconductive shield materials used in power cables can acquire excellent properties by the use of a small amount of CNTs. Therefore, we fabricated specimens using a solution mixing method. We investigated the thermal properties of the CNT, such as its storage modulus, loss modulus, and its tan delta using a dynamic mechanical analysis 2980. We found that a high thermal resistance level is demonstrated by using a small amount of CNTs. We also investigated the chemical properties of the CNT, such as the oxidation reaction by using Fourier transform infrared spectroscopy (FT-IR) made by Travel IR. In the case of the FT-IR tests, we searched for some degree of oxidation by detecting the carboxyl group (C=O). The results confirm a tendency for a high cross-linking density in a new network in which the CNTs situated between the carbon black constituent molecules show a bond using similar constructive properties.

• Preventive Nutrition and Food Science
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• 제22권2호
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• pp.107-117
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• 2017

The purpose of this study was to evaluate the antioxidant and anticholinesterase activities of yellow and white bitter yams from South Western Nigeria using methanolic extraction and simulated gastrointestinal digestion models. The phenolic compounds in the bitter yam varieties were evaluated by high performance liquid chromatography with a diode array detector (HPLC-DAD). The total phenolic content of the bitter yams was measured by the Folin-Ciocalteu method, reductive potential by assessing the ability of the bitter yam to reduce $FeCl_3$ solution, and the antioxidant activities were determined by the 2,2-diphenyl-1-picrylhydrazyl radical ($DPPH^{\cdot}$) scavenging activity, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation ($ABTS^{{\cdot}+}$) scavenging activity, nitric oxide radical ($NO^{\cdot}$) scavenging ability, hydroxyl radical scavenging ability, and ability to inhibit $Fe^{2+}$-induced lipid oxidation. The HPLC-DAD analysis revealed the presence of some phenolic compounds in the studied bitter yam varieties, with varying degree of quantitative changes after cooking. The antioxidant indices (total phenolic content, total flavonoid content, reducing power, $DPPH^{\cdot}$ scavenging activity, $ABTS^{{\cdot}+}$ scavenging activity, and $NO^{\cdot}$ scavenging activity) were higher in the simulated gastrointestinal digestion model compared to the methanolic extract, with the in vitro digested cooked white bitter yam ranking higher. Similarly, the in vitro digested yams had a higher inhibitory action against lipid oxidation compared to the methanolic extracts, with the cooked white bitter yam ranking high. The methanolic extracts and in vitro enzyme digests showed no acetylcholinesterase inhibitory abilities, while methanolic extracts and the in vitro enzyme digest displayed some level of butyrylcholinesterase inhibitory activities. Therefore the studied bitter yams could be considered as possible health supplements.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.198-198
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• 2016

An ideal orthopedic implant should provide an excellent bone-implant connection, less implant loosening and minimum adverse reactions. Commercial pure titanium (CP-Ti) and Ti alloys have been widely utilized for biomedical applications such as orthopedic and dental implants. However, being bioinert, the integration of such implant in bone was not in good condition to achieve improved osseointegraiton, there have been many efforts to modify the composition and topography of implant surface. These processes are generally classified as physical, chemical, and electrochemical methods. Plasma electrolytic oxidation (PEO) as an electrochemical route has been recently utilized to produce this kind of composite coatings. Mg ion plays a key role in bone metabolism, since it influences osteoblast and osteoclast activity. From previous studies, it has been found that Mg ions improve the bone formation on Ti alloys. PEO is a promising technology to produce porous and firmly adherent inorganic Mg containing $TiO_2$($Mg-TiO_2$ ) coatings on Ti surface, and the amount of Mg introduced into the coatings can be optimized by altering the electrolyte composition. In this study, a series of $Mg-TiO_2$ coatings are produced on Ti-6Al-4V ELI dental implant using PEO, with the substitution degree, respectively, at 0, 5, 10 and 20%. Based on the preliminary analysis of the coating structure, composition and morphology, a bone like apatite formation model is used to evaluate the in vitro biological responses at the bone-implant interface. The enhancement of the bone like apatite forming ability arises from $Mg-TiO_2$ surface, which has formed the reduction of the Mg ions. The promising results successfully demonstrate the immense potential of $Mg-TiO_2$ coatings in dental and biomaterials applications.

• Journal of Animal Science and Technology
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• 제48권1호
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• pp.107-114
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• 2006

CLA를 이용한 고품질 기능성 육계의 생산 가능성을 알아보기 위해 첨가수준과 급여기간에 따른 부위별 CLA 축적율과 지방산 조성 및 지방산패도를 분석하였다. CLA 축적율은 첨가수준이 증가할수록 유의적으로(P<0.05) 증가하였으며, 급여기간에 따라서도 다소 증가하는 경향을 보였다. 그러나 급여 1주와 급여 2주 및 3주의 비교에서 큰 차이는 나타나지 않았다. CLA 첨가수준에 따른 포화지방산은 증가하는 경향을 보였지만, 불포화 지방산은 감소하는 경향을 보였으며, 특히 CLA와 가장 비슷한 구조를 가지고 있는 linoleic acid(C18:2)는 CLA 함량이 증가한 만큼 감소하는 경향을 나타내었다. CLA 첨가수준에 따른 지방산패도의 변화는 첨가수준이 증가함에 따라 낮게 나타났으며, 대조구에 비해 처리구가 낮게 나타났다. 이상의 결론은 근육내 CLA 축적을 극대화 시키기 위한 최적의 급여기간은 1주이며, 지방산패도의 효과적인 억제를 위해서 첨가수준 4.8%가 가장 적합하다는 것을 나타낸다.

• 한국식품과학회지
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• 제20권5호
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• pp.704-710
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• 1988

본 실험은 여러 가지 보습제 및 방부제(Sodium lactate, Glycerol, Propylene glycol, sorbitol, Mannitol, Sodium benzoate, Potassium sorbate 및 Calcium propionate)처리를 한 중간수분식품 모델의 보수력을 등온흡습 곡선으로 처리하였다. 중간수분식품의 모델은 오징어를 재료로 사용하였고, 제조된 모델식품의 저장성도 검토하였다. 저장요인으로서는 지질산패, 색깔변화 및 곰팡이 번식을 관찰하였다. 보습제의 보수력은 mannitol

• 한국대기환경학회지
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• 제27권5호
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• pp.534-544
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• 2011

The secondary aerosol forming potential of ambient air was first measured with the Potential Aerosol Mass(PAM) chamber at Gosan supersite on Jeju island from October 22 to November 5, 2010. PAM chamber is a small flowthrough photo-oxidation chamber with extremely high OH and $O_3$ levels. The OH exposure in the PAM chamber was $(2{\pm}0.4){\times}10^{11}{\sim}(6{\pm}1.2){\times}10^{11}$ molecules $cm^{-3}$ s and was similar to 2 to 5 days of aging in the atmosphere. By periodically turning on and off UV lamps in the PAM chamber, ambient aerosol and newly formed aerosol (e.g. called as PAM aerosol) was alternately measured. Aerosol number and mass concentration in the range of 10~487 nm in diameter was measured by SMPS 3034. With UV lamps on, the nucleation mode particles smaller than 50 nm in diameters were formed. Their number concentration was greater than 105 $cm^{-3}$, leading to increase in aerosol mass by 0~8 ${\mu}gm^{-3}$. The variations of PAM and ambient aerosols were greatly dependent on characteristics of air masses such as precursor concentrations and degree of aging. This preliminary results suggests that PAM chamber is useful to assess the aerosol formation potential of air mass and its impact on the air quality. The further analysis of data with gaseous and particulate measurements will be done.

• 대한의용생체공학회:의공학회지
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• 제43권1호
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• pp.1-10
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• 2022

Non-alcoholic fatty liver disease(NAFLD) is excessive hepatic lipid accumulation mainly caused by obesity. This study aimed to evaluate whether micro-current stimulation(MCS) could modulate lipid metabolism regarding the Sirt1/AMPK pathway, fatty acid β-oxidation pathway, and lipolysis and lipogenesis-related factors in FL83B cells. For the NAFLD cell model, FL83B cells were treated with oleic acid for lipid accumulation. MCS were stimulated for 1 hr and used frequency 10 Hz, duty cycle 50%, and biphasic rectangular current pulse. The intensity of MCS was divided into 50, 100, 200, and 400 ㎂. Through the results of Oil red O staining, it was confirmed that MCSs with the intensity of 200 ㎂ and 400 ㎂ significantly reduced the degree of lipid droplet formation. Thus, these MCS intensities were applied to western blot analysis. Western blot analysis was performed to analyze the effects of MCS on lipid metabolism. MCS with the intensity of 400 ㎂ showed that significantly activated the Sirt1/AMPK pathway, a key pathway for regulating lipid metabolism in hepatocytes, and fatty acid β-oxidation-related transcription factors. Moreover, it activated the lipolysis pathway and suppressed lipogenesis-related transcription factors such as SREBP-1c, FAS, and PPARγ. In the case of MCS with the intensity of 200 ㎂, only PGC1α and SREBP-1c showed significant differences compared to cells treated only with oleic acid. Taken together, these results suggested that MCS with the intensity of 400 ㎂ could alleviate hepatic lipid accumulation by modulating lipid metabolism in hepatocytes.

• Composites Research
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• 제35권4호
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• pp.242-247
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• 2022

본 연구는 기존의 폐CFRP를 재활용하여 얻은 재생 탄소섬유를 다시 CFRP 제조에 활용하는 대신 탄소를 모재로 구성하는 탄소/탄소 (Carbon/Carbon, C/C) 복합소재를 제조하는 원료로 활용하기 위한 것이다. 먼저 일반적으로 많이 활용되는 에폭시수지 복합재료의 열분해 공정에 산화-불활성 분위기 변환 기술을 적용하여 1~2% 수준의 잔탄률을 19%까지 향상시켰으며, 이를 통해 에폭시수지 활용 C/C 복합재료 제조 가능성을 확인하였다. 다만, 산화-불활성 분위기 제어를 통한 열분해 공정으로 얻은 탄소의 경우 산소결합도가 높아 추후 개선 연구가 필요한 것으로 나타났다. 또한, 폐CFRP를 열분해 열처리 후 파쇄 및 해쇄 공정을 통해 단섬유 C/C 복합재료 시험편을 제조하였으며 이에 대한 기계적 물성 평가를 통해 최적 공정 조건을 도출하였다.

• 대한화장품학회지
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• 제25권1호
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• pp.6-22
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• 1999

천연고분자인 키틴으로부터 저분자 키토산을 얻은 후 이를 아질산을 이용한 분해반응에 의해 세포증식효과 및 상처치유효과 등의 생리적인 효과가 있는 키토산 올리고당을 합성하였다 이를 위해 아질산을 이용하여 deamination한 후, sodium borohydride로 환원시켜 reducing-end residue들을 alditol unit로 치환하였으며 MBTH시약을 사용하여 반응이 진행하였음을 확인하였다. 얻어진 키토산 올리고 당의 분자량 분포를 HPLC로 확인한 결과 중합도가 2∼6 인 올리고당이 얻어졌음 을 알 수 있었다. 상대습도 43％와 81％에서 측정한 흡습력 실험결과, 글리세린 에 대해 각각 63％, 57％의 흡습력을 보였으며, 상대습도 43％와 실리카겔 분위기 하의 보습력 측정결과, 각각 98％, 91％의 수분잔존률을 나타내었다 키토산 올리고당은 0,000032∼0.01％ 농도 범위에서 세포증식효과를 보였으며, 2％와 20％로 처리한 경우 상처치유효과를 나타내었다.

• 한국식품과학회지
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• 제41권6호
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• pp.628-635
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• 2009

금강밀 또는 Dark Northern Spring(DNS)밀의 기울과 배아로부터 추출한 유지(WBG유)를 빛을 차단하고 $50^{\circ}C$에서 12일 동안 저장하면서 과산화물값, 지방산조성 변화로 자동산화안정성을 평가하였고 토코페롤과 토코트리엔올, 카로티노이드, 인지질 함량 변화도 함께 측정하였다. 금강밀과 DNS밀에서 추출한 WBG유는 초기 과산화물값에 뚜렷한 차이를 보이지 않았으나 금강밀 WBG유는 DNS밀 WBG유에 비해 높은 유리지방산값을 보였다. 또한 금강밀 WBG유는 DNS밀 WBG유보다 리놀레산이, DNS밀 WBG유는 금강밀 WBG유보다 올레산이 유의하게 더 많았다. 인지질 함량은 DNS밀 WBG유에서 많았으며 토코페롤과 카로티노이드 함량은 반대 경향을 보였다. 금강밀과 DNS밀에서 추출한 WBG유는 산화기간이 증가함에 따라 과산화물값이 유의하게 증가하였으며, 산화속도는 두 기름 사이에 유의한 차이가 없었다. 금강밀과 DNS밀 WBG유의 자동산화 중 카로티노이드와 인지질은 모두 유의한 차이를 보이며 분해되었고, 인지질함량이 WBG유의 자동산화정도와 높은 상관관계를 보여주었다.