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        검색결과 57

        1.
        2019.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, a process is developed for 3D printing with alumina (Al2O3). First, a photocurable slurry made from nanoparticle Al2O3 powder is mixed with hexanediol diacrylate binder and phenylbis(2,4,6- trimethylbenzoyl) phosphine oxide photoinitiator. The optimum solid content of Al2O3 is determined by measuring the rheological properties of the slurry. Then, green bodies of Al2O3 with different photoinitiator contents and UV exposure times are fabricated with a digital light processing (DLP) 3D printer. The dimensional accuracy of the printed Al2O3 green bodies and the number of defects are evaluated by carefully measuring the samples and imaging them with a scanning electron microscope. The optimum photoinitiator content and exposure time are 0.5 wt% and 0.8 s, respectively. These results show that Al2O3 products of various sizes and shapes can be fabricated by DLP 3D printing.
        4,000원
        2.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Rare earth magnets are the strongest type of permanent magnets and are integral to the high tech industry, particularly in clean energies, such as electric vehicle motors and wind turbine generators. However, the cost of rare earth materials and the imbalance in supply and demand still remain big problems to solve for permanent magnet related industries. Thus, a magnet with abundant elements and moderate magnetic performance is required to replace rare-earth magnets. Recently, a”-Fe16N2 has attracted considerable attention as a promising candidate for next-generation non-rare-earth permanent magnets due to its gigantic magnetization (3.23 T). Also, metastable a”-Fe16N2 exhibits high tetragonality (c/a = 1.1) by interstitial introduction of N atoms, leading to a high magnetocrystalline anisotropy constant (K1 = 1.0MJ/m3). In addition, Fe has a large amount of reserves on the Earth compared to other magnetic materials, leading to low cost of raw materials and manufacturing for industrial production. In this paper, we review the synthetic methods of metastable a”-Fe16N2 with film, powder and bulk form and discuss the approaches to enhance magnetocrystalline anisotropy of a”-Fe16N2. Future research prospects are also offered with patent trends observed thus far.
        4,000원
        3.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the effect of the content of MgO-CaO-Al2O3-SiO2 (MCAS) glass additives on the properties of AlN ceramics is investigated. Dilatometric analysis and isothermal sintering for AlN compacts with MCAS contents varying between 5 and 20 wt% are carried out at temperatures ranging up to 1600℃. The results showed that the shrinkage of the AlN specimens increases with increasing MCAS content, and that full densification can be obtained irrespective of the MCAS content. Moreover, properties of the AlN-MCAS specimens such as microhardness, thermal conductivity, dielectric constant, and dielectric loss are analyzed. Microhardness and thermal conductivity decrease with increasing MCAS content. An acceptable candidate for AlN application is obtained: an AlN-MCAS composite with a thermal conductivity over 70 W/m·K and a dielectric loss tangent (tan δ) below 0.6 × 10−3, with up to 10 wt% MCAS content.
        4,000원
        6.
        2018.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, MgO–CaO–Al2O3–SiO2 (MCAS) nanocomposite glass powder having a mean particle size of 50 nm and a specific surface area of 40 m2/g is used as a sintering additive for AlN ceramics. Densification behaviors and thermal properties of AlN with 5 wt% MCAS nano-glass additive are investigated. Dilatometric analysis and isothermal sintering of AlN-5wt% MCAS compact demonstrates that the shrinkage of the AlN specimen increases significantly above 1,300oC via liquid phase sintering of MCAS additive, and complete densification could be achieved after sintering at 1,600oC, which is a reduction in sintering temperature by 200oC compared to conventional AlN-Y2O3 systems. The MCAS glass phase is satisfactorily distributed between AlN particles after sintering at 1,600oC, existing as an amorphous secondary phase. The AlN specimen attained a thermal conductivity of 82.6 W/m·K at 1,600oC.
        4,000원
        7.
        2018.06 구독 인증기관 무료, 개인회원 유료
        Codium fragile (Suringar) Hariot is an edible green seaweed that belong to the Codiaceae family and has been used in Oriental medicine for the treatment of enterobiasis, dropsy, and dysuria. Methanol extract of codium fragile has anti-oxidant, anti-inflammatory and anti-cancer properties, although the anti-cancer effect on oral cancer has not yet been reported. In this study, we investigated the anti-cancer activity and the mechanism of cell death by methanol extracts of Codium fragile (MeCF) on human FaDu hypopharyngeal squamous carcinoma cells. Our data showed that MeCF inhibits cell viability in a dose-dependent manner, and markedly induced apoptosis, as determined by the MTT assay, Live/Dead assay, and DAPI stain. In addition, MeCF induced the proteolytic cleavage of procaspase -3, -7, -9 and poly(ADP-ribose) polymerase(PARP), and upregulated or downregulated the expression of mitochondrial-apoptosis factor, Bax(pro-apoptotic factor), and Bcl-2(anti-apoptotic factor), . Futhermore, MeCF induced a cell cycle arrest at the G1/S phase through suppressing the expression of the cell cycle cascade proteins, p21, CDK4, CyclinD1, and phospho-Rb. Taken together, these results indicated that MeCF inhibits cell growth, and this inhibition is mediated by caspase- and mitochondrial-dependent apoptotic pathways through cell cycle arrest at the G1/S phase in human FaDu hypopharyngeal squamous carcinoma cells. Therefore, methanol extracts of Codium fragile can be provided as a novel chemotherapeutic drug due to its growth inhibition effects and induction of apoptosis in human oral cancer cells.
        4,000원
        8.
        2017.12 구독 인증기관 무료, 개인회원 유료
        Ficus carica L. (common fig), one of the first plants cultivated by humans, originated in the Mediterranean basin and currently grows worldwide, including southwest Asia and South Korea. It has been used as a traditional medicine for treatment of metabolic, cardiovascular, and respiratory diseases as well as hemorrhoids and skin infections. Its pharmacological properties have recently been studied in detail, but research on the anti-cancer effect of its latex has been only been studied on a limited basis on several cell lines, such prostate cancer, breast cancer, and leukemia. In this study, we investigated the anti-cancer activity of the latex of Ficus carica L.and its underlying mechanism in FaDu human hypopharynx squamous carcinoma cells. (See Ed. note above) We confirmed through SDS-PAGE analysis and gelatinolytic activity analysis that the latex of Ficus carica contains cysteine protease ficin. Our data showed that the latex inhibited cell growth in a dose-dependent manner. In addition, the latex treatment markedly induced apoptosis in FaDu cells as determined by FACS analysis, elevated expression level of cleaved caspase-9, -3 and PARP (poly (ADP-ribose) polymerase), and. increased the expression of Bax (pro-apoptotic factor) while decreasing the expression of Bcl-2 (anti-apoptotic factor). Taken together, these results suggested that latex containing the ficin inhibited cell growth and induced apoptosis by caspase and the Bcl-2 family signaling pathway in FaDu human hypopharynx squamous carcinoma cells. These findings point to the potential of latex of Ficus carica to provide a novel chemotherapeutic drug due to its growth inhibition effects and induction of apoptosis in human oral cancer cells.
        4,000원
        9.
        2017.06 구독 인증기관 무료, 개인회원 유료
        Anthriscus sylvestris (L.) Hoffm. is a perennial herb found widely distributed in various regions of Korea, Europe, and New Zealand. The root of A. sylvestris have been extensively used in the treatment for antitussive, antipyretic, cough remedy in Oriental medicine, but the physiologically active function of the leaf of A. sylvestris is as yet unknown. In this study, we investigated the anti-cancer activity and the mechanism of cell death of water extracts of leaf of Anthriscus sylvestris (WELAS), on human FaDu hypopharyngeal squamous carcinoma cells. Our data showed that WELAS treatment inhibited cell viability in a concentration- and time-dependent manner. In addition, the treatment of WELAS markedly induced apoptosis in FaDu cells, as determined by the viability assay, DAPI stain and FACS analysis. WELAS also increased the proteolytic cleavage of procaspase-3, -9 and PARP (poly(ADP-ribose) polymerase). In addition, exposure to WELAS decreased the expression of Bcl-2 (an anti-apoptotic factor), but increased the expression of Bax (a pro-apoptotic factor), suggesting that mitochondria-dependent apoptotic pathways are mediated in WELAS-induced apoptosis. Taken together, these results indicate that water extracts of leaf of A. sylvestris inhibits cell growth and induces apoptosis via the mitochondrial-dependent apoptotic pathway in FaDu human hypopharyngeal squamous carcinoma cells. Therefore, we propose that the water extracts of leaf of A. sylvestris is a novel chemotherapeutic drug, having growth inhibitory properties and induction of apoptosis in human oral cancer cells.
        4,000원
        10.
        2017.05 구독 인증기관·개인회원 무료
        CO2 분리막 기술은 화학 유해 물질 사용·배출이 없는 친환경 기술로, 규모나 위치, 적용처별 사업 다각화가 가능한 기술이다. 전력연구원에서는 저비용 분리막 대량 생산 기술을 확보하고, 적층 방식의 분리막 모듈 상용화를 추진 중에 있다. Lab-scale의 분리 모듈의 성능 평가 결과를 기반으로 96% 순도, 90% 포집률을 동시달성하는 분리막 공정의 설계를 완료하였다. 현재 ’17년 8월 준공을 목표로 세계 최대 규모인 1MW급 CO2 분리막 테스트 베드를 당진 화력에 건설진행 중이다.
        11.
        2016.12 구독 인증기관 무료, 개인회원 유료
        Anthricin (Deoxypodophyllotoxin), a naturally occurring flavolignan, has well known anti-cancer properties in several cancer cells, such as prostate cancer, cervical carcinoma and pancreatic cancer. However, the effects of Anthricin are currently unknown in oral cancer. We examined the anticancer effect and mechanism of action of Anthricin in human FaDu hypopharyngeal squamous carcinoma cells. Our data showed that Anthricin inhibits cell viability in a dose- and time-dependent manner (IC50 50 nM) in the MTT assay and Live & Dead assay. In addition, Anthricin treated FaDu cells showed marked apoptosis by DAPI stain and FACS. Furthermore, Anthricin activates anti-apoptotic factors such as caspase-3, -9 and poly (ADP-ribose) polymerase (PARP), suggesting that caspase-mediated pathways are involved in Anthricin- induced apoptosis. Anthricin treatment also leads to accumulation of the pro-apoptotic factor Bax, followed by inhibition of cell growth. Taken together, these results indicate that Anthricn-induced cell death of human FaDu hypopharyngeal squamous carcinoma cells is mediated by mitochondrial-dependent apoptotic pathway. In summary, our findings provide a framework for further exploration on Anthricin as a novel chemotherapeutic drug for human oral cancer.
        4,000원
        12.
        2014.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 파장의 위상차를 변화시켜 균일한 살균을 유도할 수 있고 저전력으로 효과를 높일 수 있는 QRD(quadratic residue diffusor) 마이크로파를 이용하여 챔버 내부의 위치에 따른 온도변화를 측정하여 효율성과 균등성을 분석한 결과는 다음과 같다. 챔버 내부의 수직 35cm, 중앙 위치에서는 7kW 조사시 가장 효율이 높게 나타났고, 좌우측 위치에서는 5kW에서 효율성이 높았다. 그리고 마그네트론 No. 1, 2, 3에서 3kW로 하였을 때, Bar의 위치에 따른 온도 균등성은 1Bar와 2Bar의 위치에서는 거의 비슷하게 나타났다. 마그네트론 No. 3, 4, 5의 3kW로 하였을 경우에는 3Bar에서 온도가 약 10~ 20% 정도 높게 나타났고 마그네트론 용량을 5, 7, 9kW로 하였을 때, 조사 시간에 대한 평균 온도는 Bar의 위치에 무관하게 거의 유사한 형태로 증가하였다. 반면에 챔버의 적정 내용적에 대한 효율성은 조사용량에 반드시 비례하지는 않았다. 마그네트론 3kW를 60, 120, 180초 동안 조사하였을 경우 마그네트론 조사 위치에 따라 구석 부분에서 약 5~10oC 더 높게 상승하였고 수평면의 위치별 온도 분포는 비교적 균일하였으며 부분적으로 구 석부분에서 약간 더 온도가 상승하는 경향이 있었다. 마그네트론 5, 7, 9kW 조사에서는 Bar의 위치와 상관없이 전반적으로 온도가 비교적 균일하게 상승하고 있었다.
        4,000원
        13.
        2011.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this research was to provide basic educational data on the proper eating habits of children who use the community children center. The results of the research conducted by polling the fourth, fifth, and sixth-grade children of the community children centers are summarized as follows. Male children had more meals and ate them faster than those of female children, and they also tended to watch more TV and read books. Moreover, children of families headed by fathers ate until they were full, whereas children of households headed by mothers ate less. More female than male children skipped breakfast, and the percentage of children who had their meals alone was high among children reared by their grandfathers. Most of the children ate only what they liked. Moreover, male children ate only particular fruits and vegetables, whereas female children ate only beans and miscellaneous cereals. Most of the children recognized that they had eating problems, such as eating only what they liked and eating meals on irregular schedules. Such eating habits were affected mainly by family members such as parents, brothers, and sisters. Female children scored higher than male children in terms of nutrition and hygiene knowledge. Approximately 40~50.3% of all subjects became interested in nutrition and hygiene education at the community children center. Most of the children recognized that nutrition and hygiene education is necessary at the community children center. They also recognized their own eating problems and wanted nutrition and hygiene education to be taught at the community children center. Accordingly, regular educational activities and meals for children in the community children center considered a children`s particular home background to improve eating habits in the children.
        4,300원
        14.
        2011.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In using both hands, everyone dominantly use one hand and it is called left-handedness or right-handedness person. Measurements of grip and pinch strength provide objective indexes to represent functional integrity of the upper extremity. This study was conducted for thirty female college students(19 right-handedness and 11 lefthandedness). For assessment of the type of handedness, questionnaire was used; for grip strength, Jamar dynamometer was used; for pinch strength, Jamar pinch gauge was used. In right handedness, the grip and pinch strength of the dominant right hand was significantly higher than those of the non-dominant hand. In addition, regular exercises were shown to give influences on reduction of strength gaps between dominant and non-dominant hands. In both groups of left and right handedness, the grip and pinch strength of the dominant hand were significantly higher than those of the non-dominant hand, and regular exercises were shown to give influences on reduction of strength gaps between dominant and non-dominant hand.
        4,000원
        15.
        2016.10 서비스 종료(열람 제한)
        Background : Some of invasive plants, which were introduced from foreign countries, have caused problems in Korea. Invasion of these invasive plants in the ecosystem threatens the habitat of endemic species, reducing biodiversity, and causing a disturbance in the ecological system. Hypochaeris radicata L. (Asteraceae), the most invasive plants in Korea, particularly in Jeju Island, invade farmland, and autochthonous forest, establishing monocultures and modifying the ecosystem structure. This invasive species has become a serious environmental problem because they displace the indigenous plant species. This study was conducted to evaluate the antioxidantive effects of ethanolic extracts from different parts (root, stem, seed and leaf) of the invasive exotic species Hypochaeris radicata L. Methods and Results : The aim of present study was to estimate the total phenolic and flavonoid contents and to investigate in vitro antioxidant potential of ethanolic leaf, root, seed, and stem extracts of the Hypochaeris radicata. Antioxidant activity was assessed by using 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assay, reducing power activity, [2,2-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid)] ABTS+ assay and ferrous ion chelating activity. The total phenolic and flavonoid contents were also determined and expressed in gallic acid and quercetin equivalent respectively. The results of the study indicate that the ethanolic extracts of the leaf, root, seed, and stem of H. radicata posses significant scavenging activity against DPPH (21.25% for leaf, 34.98% for root, 60.76% for seed and 45.25% for stem at 250 μg/ml each) and ABTS+ radical scavenging activity (14.85% for leaf, 17.40% for root, 35.91% for seed and 24.70% for stem at 250 μg/ml each), reducing power activity (0.178 absorbance at 300 μg/ml for leaf, 0.211 absorbance at 300 μg/ml for root, 0.447 absorbance at 300 μg/ml for seed, 0.276 absorbance at 300 μg/ml for stem). The free radical scavenging and antioxidant activities may be attributed to the presence of adequate phenolic (gallic acid content is 361.92.98 μg/g in leaf, 356.59μg/g in root, 719.72 μg/g in seed and 512.08 μg/g stem) and flavonoid compounds (219.52 μg/g in leaf, 75.67μg/g in root, 281.39 μg/g in seed and 215.66 μg/g stem). This study revealed that the ethanolic extracts of both leaf, root, seed and stem of H. radicata has demonstrated significant antioxidant activity. Conclusion : In conclusion, the present study has demonstrated that Hypochaeris radicata seed ethanol extracts are rich in phenolics and have a strong antioxidant activity and a radical-scavenging action in all of the tested methods. This suggests that Hypochaeris radicata is a good source of natural antioxidants.
        17.
        2012.09 KCI 등재 서비스 종료(열람 제한)
        화장품 분야에 있어서 마이크로 에멀젼은 잘 알려져 있는 처방이다. 액정형 에멀젼은 마이크로 에멀젼의 한 종류이며, 액정형 에멀젼은 기능성 성분을 포집하는데 사용되어 왔다. 액정은 이름이 의미하듯이 액체와 고체 결정의 중간의 성질을 가지는 물질 상태이다. 주로 계면활성제 이중층 또는 마이셀로 이루어지는데 종류도 다양하고 모양도 상당히 많다. 최근, 마이크로 에멀젼은 콜로이드 과학 분야에서 열역학적으로 안정성을 향상시키기 위해 연구되고 있다. 이번 연구에서는 PEG-8 Capryliccapric Glycerides 와 Polyglyceryl-3 Diisostearate 유화제를 사용하여 마이크로 에멀젼을 제조하였다. 오일과 유화제의 함량 및 2가지 유화제의 비율에 따라 제조된 마이크로 에멀젼을 연구하였다. 또한, 이러한 실험 결과를 바탕으로 기능성 성분을 함유한 액정형 에멀젼의 일종인 페이셜 오일과 클렌징 오일을 개발하는데 그 의의가 있다.
        18.
        2011.10 KCI 등재 서비스 종료(열람 제한)
        고감미 다수성 계통인 자가수정 스테비아의 hypocotyl 절편체를 이용하여 대량증식방법 개발에 대한 결과는 다음과 같다. 선발된 자가수정개체는 초장이 72.0~120.7 cm로 분포되어 있었고, 분지수는 4.9~56.6개로 분포되어 있었다. HPLC 분석을 통하여 rebaudioside-A(RA)성분이 평균함량 55.2%이상 함유된 자가수정 개체를 선발하였다. 스테비아의 hypocotyl 절편체를 이용하여 MS배지에 1.5 mg/L BA와 0.5 mg
        20.
        2010.08 KCI 등재 서비스 종료(열람 제한)
        국내에서 육성된 품종인 ‘일품’을 대상으로 현미배양 후대의 주요 농업형질에 대한 변이체의 발생양상과 범위 및 종류등을 조사하고 변이집단의 크기와 변이집단의 육종적 유용성에 대한 결과는 다음과 같다. ‘일품’ 완숙현미 유래 캘러스로 부터 424개체의 식물체를 재분화하고 297개체로부터 종자를 채종하여 계통 재배하면서 간장, 출수기 등 주요 농업형질과 형태적 변이를 조사하였다. 주요 농업형질과 형태적 특성이 모품종과 다른 변이체는 전체의 21.5%인 64계
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