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        검색결과 149

        101.
        2017.12 KCI 등재 서비스 종료(열람 제한)
        원자로 내 사고발생 시 냉각수의 비등으로 기포가 발생하고, 기포율을 측정하기 위하여 열수력 안전 분 야에서는 주로 Optical Fiber Probe(OFP)나 광학 카메라를 이용하여 측정하지만 기하학적 구조의 한계로 인 해 17 × 17 배열의 봉 다발 내에 장비를 설치하는 것에는 어려움이 있다. 본 연구는 예비 연구로서 봉 다발 에 적용하기 전 X선 시스템과 다양한 모사 팬텀을 이용하여 연구 가능성 평가를 수행하였다. 라디오그라피 및 토모그라피 실험을 통해 X선 발생 장치의 관전압 130 kVp, 관전류 1 mA가 적합하였다. 또한, 기포 해상 도 팬텀을 통해 가시적으로 1 mm 크기의 구멍에 대해 측정이 가능하였으며 막대 팬텀을 이용한 대조도 평 가의 경우 프레온 내부에서 대조도가 상대적으로 떨어짐을 확인할 수 있었다. 그러나 영상 재구성 시 일그 러짐이 없는 좋은 영상을 획득할 수 있었다. 기포 발생 팬텀 실험을 통해 기포의 유동 방향 확인 및 단층 영상을 획득할 수 있었고, Image J 툴을 이용하여 하나의 단층영상에 대해 18 %의 기포율을 측정할 수 있 었다. 본 연구는 핵연료 주변 기포율 측정을 위한 선행 연구를 수행하였고 지속적인 연구를 위한 기초 연 구로서 활용할 수 있을 것이다.
        103.
        2017.08 KCI 등재 서비스 종료(열람 제한)
        To investigate skin-whitening effect of Adenophora triphylla var. japonica sprout extract, antioxidant activity, inhibitory effect on tyrosinase and melanin synthesis in B16/F10 melanoma cell were examined. Total phenolic content (246.25 ㎎ GAE/g) and total flavonoid content (303.94 ㎎ RE/g) of ethyl acetate fraction from Adenophora triphylla sprout (EFAT) showed the highest contents than other fractions (n-hexane, chloroform and distilled water). Antioxidant activities of EFAT has been evaluated using ABTS, DPPH radical scavenging activities, FRAP and inhibitory effect of lipid peroxidation. EFAT showed excellent radical scavenging activity and inhibitory effect on MDA production. Inhibitory effect of tyrosinase as a major enzyme of melanin synthesis was also measured. In these results, EFAT showed higher inhibitory effect against L-DOPA (51.27%) than L-tyrosine. IC50 value on α-glucosidase was 41.93 ㎍/㎖. In B16/F10 melanoma cells, EFAT inhibited melanin synthesis at 200 ㎍/㎖ concentration (about 42% decrease). Finally, main physiological compounds of EFAT were identified as a rutin and a chlorogenic acid using high performance liquid chromatography.
        104.
        2017.04 KCI 등재 서비스 종료(열람 제한)
        This study was conducted to evaluate the contents of total polyphenol and flavonoid, and the effect of antioxidant, antimicrobial activities and cytotoxicity in vitro by different solvent fractions from Orostachys japonicus. The ethylacetate fraction extract for O. japonicus contained 634.48 ㎍/g polyphenol and 205.20 ㎍/g flavonoid. The ABTS radical scavenging ability of ethylacetate fraction extract at 1 ㎎/㎖ was higher than 95% which is comparable to ascorbic acid of 97%. The APX enzymatic activity and CAT activity were 1125.89 μmol ascorbate oxidized/min/㎎ protein and 119.87 H2O2 decomposed/ min/㎎ protein, respectively. In disc agar plate diffusion assay, the extract gave rise to a larger inhibition circle with Listeria monocytogenes, Staphylococcus epidermidis, Staphylococcus aureus and Malassezia furfur strains compared with antibiotics kanamycin suggestive of high antibiotic activity. The cytotoxicity of extracts of O. japonicus was significant differences between solvent fractions. That is, the cytotoxic effect against human cancer cell was higher in ethylacetate fraction extract than other fraction extracts. These results suggest that fraction extract of O. japonicus might be very effective and economical in developing natural antioxidant and antimicrobial.
        105.
        2017.04 서비스 종료(열람 제한)
        According to the KCI 2012, it is presented that steel fiber can replace minimum shear reinforcement when beams are designed. However, there is no standard for columns, and there is a lack of research on SFRC columns. Therefore, it is evaluated how much the capacity of columns increases according to the volume fraction of steel fiber through the cyclic lateral loading tests. Also, it is evaluated whether steel fiber can replace transverse reinforcements in concrete columns.
        106.
        2017.03 KCI 등재 서비스 종료(열람 제한)
        목화진딧물과 복숭아혹진딧물은 채소를 포함한 다양한 작물에 큰 피해를 주는 해충이다. 이들 해충의 친환경 방제를 위해 진딧물에 병원성이 높은 곰팡이(B. bassiana) 유래 대사물 질을 이용한 방제 연구를 수행하였다. 이 균주의 배양여액의 살충율은 목화진딧물에 처리 3일 후 100%, 복숭아혹진딧물에 처리 5일 후 99%였다. 이 추출물을 CHCl3 : MeOH 비율을 달리하여 silica gel column chromatography 한 결과, 50:1 (CHCl3 : MeOH)의 추출물 분획의 살충률이 목화진딧물과 복숭아혹진딧물에 각 80%와 75.4%로 다른 분획에 비해 현저하게 높았다. 또 각 용매비율별 추출물을 1:1로 혼합하여 처리한 결과, 분획 추출물 혼합에 의한 상승효과는 보이지 않았으며 두 진딧물에 모두 50:1 (CHCl3 : MeOH) 단독처리에서 살충률 (목화진딧물 77.3%, 복숭아혹진딧물 76.4%)이 가장 높았으며 50:1 + 70:1이 두 번째로 높았 다(목화진딧물 72%, 복숭아혹진딧물 70.2%). 앞으로 안정적인 진딧물 방제를 위해 50:1 분 획 추출물 내 진딧물 살충성 물질을 분리 동정 및 대량생산 연구를 진행할 예정이다.
        107.
        2017.02 KCI 등재 서비스 종료(열람 제한)
        Background: To date, the anti-wrinkle efficacy of phellodendri cortex has not been defined. In this study, we investigated the nitric oxide (NO) production and elastase inhibitory activities of 80% methanol extract of Phellodendri cortex and its ethyl acetate fraction. Methods and Results: We prepared 80% methanol extract, and its fractions from phellodendri cortex. The treatment of RAW 264.7 cell with 25㎍/㎖ 80% methanol extract and ethyl acetate fraction resulted in no toxicity. We conducted assays of nitric oxide (NO) production and elastase inhibition. In the NO production assay, the ethyl acetate fraction showed an inhibitory effect approximately 17 times stronger than the 80% methanol extract. In elastase inhibitory assay, the ethyl acetate fraction also showed a stronger effect than the 80% methanol extract. In order to standardize the extract and fraction, we used TLC to separate the extract and observed the plate under UV light. We confirmed that the known pharmacological ingredients berberine, and palmatine in the 80% methanol extract and the ethyl acetate fraction. Conclusions: These results indicated that phellodendri cortex extract and its ethyl acetate fraction produced strong inhibitory effect on elastase and NO production.
        108.
        2016.10 서비스 종료(열람 제한)
        Background : Reactive oxygen species (ROS), whether produced endogenously as a consequence of normal cell functions or derived from external sources, pose a constant threat to cells living in an aerobic environment as they can result in severe damage to DNA, protein, and lipids. The effects of Valeriana fauriei extract and fractions on hydrogen peroxide-induced neuronal cell damage are studied. Methods and Results : Oxidative stress plays an important role in the pathological process of neurodegenerative diseases. Valeriana fauriei extract (VFE) and EA fractions (VFEA) was investigated total phenolic contents using method. VFE of total phenolic contents had 2.54 ± 0.01 mg/g, also, VFEA had a 18.78 ± 0.03 mg/g. High phenolic content of the VFEA is expected to better the inhibition of oxidative stress. VFE and VFEA were experimented to inhibit ROS induced 200 μM 3-morpholinosydnonimine (SIN-1). VFE of inhibit SIN-1 induced-ROS dose dependently and signficantly. In addition, VFEA inhibition was also dose dependant and significant. Moreover, Treatment of SH-SY5Y and SK-N-SH cells with VFEA significantly reduced hydrogen peroxide-induced generation of intercellular ROS. Conclusion : From the above results, we may suggest that VFEA might have useful as a material for functional food and pharmaceutics for the pathological process of neurodegenerative diseases.
        109.
        2016.10 서비스 종료(열람 제한)
        Background : Perilla frutescens L. is valuable as a medicinal plant as well as a natural medicine and functional food. Limonene perilla collected from various places showed 60% limonene compounds. However biological activity of these accession has not been reported before. Therefore, this study was conducted to investigate the biological activity of limonene perilla. Methods and Results : Fractional solvent extracts were obtained by using organic solvents such as n-hexane, chloroform, ethyl acetate, n-BuOH, and aqueous solvent from different parts of limonene perilla extracted initially in 70% EtOH. We investigated the effects of limonene perilla on total phenol and flavonoid contents, FRAP (Ferric Reducing Antioxidant Power), total saponin contents and tyrosinase inhibition activity. Leaves of limonene perilla produced the highest total phenolic contents (29.88 mg·CAE/g), flavonoid (8.39 mg·QE/g) and saponin contents (47.77 mg·GIE/g) than stems and roots of limonene perilla. FRAP of leaves was 823.00±3.58 μM·FeSO4·E/mg. Tyrosinase inhibition activity rate was 40.31% in 70% ethanol extracts from leaves of limonene perilla. Conclusion : This results suggest that leaf of limonene perilla fractions has significant antioxidant activity. Also, limonene perilla could be used as a functional biomaterial in developing cosmetics and functional foods.
        110.
        2016.10 서비스 종료(열람 제한)
        Background : This study, the fraction for testing the efficacy of the Astragalus extract was concentrated active ingredient. The concentrated fraction was applied to a cosmetic material that Astragalus testing results confirmed that the improved efficacy. Methods and Results : The fractions were performed using an n-butanol solvent for increasing the efficacy of the Astragalus extract, by using the material fractions collected to compare and ultimately an increase in whitening and wrinkle efficacy. The solvent to be used in the fractions was used for the n-butanol good dissolution to the effective substance(Astragaloside, Isoflavonoid). It increased approximately 6.5 times the sample extract and the n-butanol fraction of the Astragalus as a result Astragaloside 15 ppm, 97 ppm respectively analyzed by HPLC equipment, isoflavonoid content was confirmed by an increase in the content of the fractions increased 4.5 times to 280 ppm, 1,260 ppm. Tyrosinase inhibitory effect, respectively IC50 5.70 mg/mL, IC50 1.02 mg/mL to, Collagenase producing ability is IC50 4.88 mg/mL, IC50 0.93 mg/mL with n-butanol fraction was good whitening, anti-wrinkle efficacy than the extract. Sensory evaluation was conducted in the same amount of sample, using a purified Astragalus cosmetics received high marks. Stability evaluation(MTT assay) was checked for more than 100% cell viability at the concentration 2,000 ppm. Conclusion : n-butanol fraction of Astragalus was subjected to a component analysis and In vitro test, it was confirmed an increase active ingredient content. The results of sensory evaluation and stability evaluation, it was confirmed been made to improve qualities as a cosmetic materials.
        111.
        2016.10 서비스 종료(열람 제한)
        Based on the study of researchers carried about SFRC, it was found that SFRC was effective to achieve flexural toughness according to higher volume fraction. On the other hand, higher volume fraction did not effect at compressive strength and toughness.
        112.
        2016.08 KCI 등재 서비스 종료(열람 제한)
        연령이 증가함에 따라 피부 내부에서는 콜라겐의 합성 능력이 떨어지고 탄력섬유의 손상 및 matrix metalloproteinase (MMPs) 발현이 증가한다. 본 연구의 목적은 눈가에 주름이 형성되기 전에 연령이 증가할수 록 피부 내부에서 피부 노화의 징후가 관찰된다는 것을 확인하고, 피부 내부에서 먼저 발생하는 노화의 징후가 칠엽담 지페노사이드 분획물 함유 크림(칠엽담 지페노사이드 크림)의 효능으로 인해 개선되는 것을 확인하는 데 있다. 이에 본 연구에서는 육안으로 눈가에 주름이 관찰되지 않는 21 ∼ 34세의 한국 여성 52명을 대상으로 임상 시험을 수행하였다. 이들에게서 연령이 증가함에 따라 피부 외부의 노화 징후가 관찰되지는 않지만 피부 내부에서 노화의 징후가 시작되는 시점을 진피치밀도 측정을 통해 확인하였다. 그리고 육안으로 주름이 관찰되 지는 않았지만, 진피치밀도가 감소하는 연령대에서 칠엽담 지페노사이드 크림을 4주 및 8주 사용한 후에 진피치 밀도 값이 유의하게 증가함을 확인하였다. 따라서 칠엽담 지페노사이드 크림이 피부 내부에서 먼저 진행되는 노화를 효과적으로 개선하는데 도움을 주며, 이 결과를 토대로 칠엽담 지페노사이드 분획물이 향후 주름 개선 기능성 화장품 개발에 활용하기 적합하다고 판단된다.
        113.
        2016.06 KCI 등재 서비스 종료(열람 제한)
        피부 기저막(basement membrane, BM)이란 표피와 진피 사이에 존재하는 특별한 구조물로 표피와 진피 를 단단히 고정시켜 피부 구조를 유지하는 데에 중요한 역할을 수행한다. 노화 및 자외선 노출에 의한 피부 기저막 의 구조적 변화와 파괴는 피부 주름 형성과 탄력 저하를 포함하는 피부노화 현상의 요인으로 여겨지고 있다. Laminin-332 (LN-332)는 피부 기저막을 구성하는 주성분으로 피부에서 표피와 진피를 단단히 고정시키는데 중요한 역할을 한다. 본 연구에서는 왕불유행 헥산 분획물(Melandrium firmum hexane fraction, MFHF)이 각 질형성세포에서 LN-332 발현에 미치는 효과를 확인하였다. 정량적 real-time PCR (RT-PCR)과 단백질 발현 분석을 통해서 MFHF가 LN-332의 mRNA 발현 및 단백질 발현을 촉진시키는 것을 확인하였다. 또한 MFHF가 어떤 신호전달 경로를 통해 LN-332 발현을 조절하는지 확인하기 위하여 p38 MAPK 억제제인 SB202190과 ERK1/2 억제제인 U0126을 처리한 결과, p38 MAPK 억제제에 의해서 LN-332 발현이 완벽히 억제됨을 확인 하였다. 또한, 피부 기저막을 구성하고 있는 콜라겐 타입 VII과 integrin α6의 mRNA 발현 역시 MFHF에 의해 증가하는 것을 확인하였다. 우리는 본 연구를 통해 MFHF가 각질형성세포에 작용하여 피부 기저막을 구성하는 성분들의 생성을 촉진할 수 있는 소재로 작용할 수 있다는 것을 확인하였다. 이러한 결과는 기저막의 구조적, 기능 적 이상에 의해 나타나는 피부노화 현상의 개선을 위해 활용할 수 있을 것이라 제안한다.
        114.
        2016.04 서비스 종료(열람 제한)
        Concrete behaves as a brittle material with low tensile strain capacity. By adding fibers, the cracking in concrete matrix is controlled, and the mechanical properties are improved. In this study, the mechanical properties of fiber reinforced concrete are compared with fiber type and fiber volume fraction. From the results, the fiber mixed in concrete must be at least 0.5% regardless fiber type, in order to ensure the compressive and flexural strength equivalent or higher than OPC.
        115.
        2016.04 서비스 종료(열람 제한)
        Concrete behaves as a brittle material with low tensile strain capacity. By adding fibers, the cracking in concrete matrix is controlled, and the durability is improved. In this study, the microstructure and Chloride diffusion resistance of fiber reinforced concrete are compared with fiber type and fiber volume fraction. From the results, the fiber mixed in concrete must be at least 0.5% regardless fiber type, in order to ensure the chloride diffusion coefficient higher than OPC at 91days. However, the micro structure distribution is affected with fiber volume fraction and fiber type at range 10~100nm.
        116.
        2016.01 KCI 등재 서비스 종료(열람 제한)
        The Intergovernmental Panel on Climate Change (IPCC) recommended the first order decay (FOD) model for estimating methane emissions from solid waste landfills. However, selecting appropriate parameter is a major challenge in methane emission modeling. The degradable organic carbon (DOC) and the fraction of degradable organic carbon which decomposes (DOCF) are the two primary parameters in the methane generation potential (L0). The DOC is the amount of organic carbon that can be decomposed by biochemical reactions in microorganisms. Chemical analysis methods are currently available to measure the DOC including using total organic carbon and element analysis methods. However, chemical analysis methods are not appropriate for determination of the DOC, which indicated that the DOC should be measured by biochemical tests. In addition, these methods should consider a fossil carbon content that needs a complex and high cost of analysis. The DOCF is an estimate of the fraction of carbon that is ultimately degraded and released from landfills. However, no methodology is provided for determination of the DOCF in landfills. Therefore, the purpose of this study was to suggest methodologies for the determination of DOC and DOCF in solid waste landfills. A biochemical methane potential (BMP) test could be used to calculate the DOC because the BMP represents an upper limit on the methane potential of a waste, which corresponds to a maximal amount of degraded organic carbon. The calculation was based on the assumption that the DOCF is 100%. In this study, two methodologies were suggested to determine the DOCF in landfills. The first one uses a new equation (DOCF = 2.76W-0.44) with moisture content in the landfill that actual methane flux data are unavailable. Moisture content is a major ecological parameter on the anaerobic biodegradability of the solid waste in the landfill. Another methodology is to use L0,Landfill/L0,BMP ratio. The L0,Landfill could be determined by a regression analysis if methane flux data were available.
        117.
        2015.10 KCI 등재 서비스 종료(열람 제한)
        This study describes a preliminary evaluation of the anti-inflammatory activity of Acrosorium yendoi Yamada extracts. A. yendoi Yamada was extracted using 80% ethanol and then fractionated sequentially with n-hexane, ethyl acetate and butanol. To screen for anti-inflammatory agents effectively, we first examined the inhibitory effect of 80% EtOH extract and solvent fractions of A. yendoi Yamada on the production of pro-inflammatory factors and cytokines stimulated with lipopolysaccharide. In addition, we examined the inhibitory effect of 80% EtOH extract and solvent fractions of A. yendoi Yamada on pro-inflammatory mediators (NO, iNOS, PGE2, and COX-2) in RAW 264.7 cells. In the sequential fractions of n-hexane and EtOAc inhibited the NO and PGE2 production and the protein level of iNOS and COX-2, and protein expression of pro-inflammatory cytokines (TNF-α, and IL-6). These results suggest that A. yendoi Yamada may have significant effects on inflammatory factors and may be provided as possible anti-inflammatory therapeutic seaweed.
        119.
        2015.10 서비스 종료(열람 제한)
        Concrete shrinkage is happened due to the cement hydration and water evaporation from early ages, and it induces crack of concrete. In this study, the crack resistance of fiber reinforced concrete was compared with fiber type and fiber volume fraction. From the results, cracking is delayed when the volume fraction is increased. And, crack resistance is improved regardless of fiber type.
        120.
        2015.07 KCI 등재 서비스 종료(열람 제한)
        본 연구는 SIFCON 형태의 고성능 강섬유보강 시멘트 복합체의 섬유혼입률에 따른 휨실험을 수행하였고, 실험결과를 바탕으로 휨성능을 평가하였다. 슬러리를 충전하는 형태로 일반 섬유보강시멘트와 달리 높은 섬유혼입률을 확보할 수 있는 장점을 가지고 있다. 주요 실험변수는 섬유혼입률 8.0%, 7.5%, 7.0%, 6.5% 및 6.0% 이며, 각 변수에 대한 휨강도 및 휨인성 특성을 분석하였다. 그 결과, 높은 섬유혼입률로 인하여 초기균열 발생 이후에도 계속적으로 하중이 증가하였으며, 최대강도 이후 충분한 잔류강도를 확보하였다. 또한 최대 50MPa 수준의 높은 휨강도를 발현하였으며, 섬유혼입률에 따른 휨강도 및 휨인성은 비례하여 증가하는 경향으로 나타났다.
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