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        검색결과 144

        24.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We aimed to predict the Italian ryegrass (IRG) productivity change of introduced and domestic varieties based on climate factors and identify suitable areas for IRG cultivation using the RCP 8.5 scenario. The minimum mean air temperature in January showed the highest correlation with productivity. The ratio of possible and low productivity areas was high in Gangwondo, and the ratio of suitable and best suitable areas was relatively high in the central and southern regions in the past 30 years. The change in the IRG cultivation area was found to be 26.9% in the best suitable area between 1981–2010 but increased significantly to 88.9% between 2090s. In the IRG suitability comparison classes between domestic and introduced cultivars, the ratio of suitable and best suitable areas was relatively high in the domestic varieties during the past 30 years. However, there is almost no difference between the IRG domestic and introduced varieties in the IRG suitability classes after the 2050s. These results can predict changes in the IRG suitability classes between domestic and introduced cultivars according to the climate change scenario, but there are limitations in accurately predicting the productivity of IRG because the results may vary depending on other environmental factors.
        4,000원
        25.
        2020.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Free-standing hybridized electrode consisting of double-walled carbon nanotubes (DWNTs) and activated carbon have been fabricated for flexible supercapacitor applications. The xanthan-gum, used in our methodology, showed high ability in dispersing the strongly bundled DWNTs, and was then effectively converted to activated carbon with large surface area via chemical activation. The homogeneously dispersed DWNTs within xanthan-gum derived activated carbon acted as both electrical path and mechanical support of electrode material. The hybridized film from highly dispersed DWNTs and activated carbon was mechanically strong, has high electrical conductivity, and exhibited high specific capacitance of 141.5 F/g at the current density of 100 mV/s. Our hybridized film is highly promising as electrode material for flexible supercapacitors in wearable device.
        4,000원
        26.
        2020.09 구독 인증기관 무료, 개인회원 유료
        Acacetin, which is present in damiana (Turnera diffusa ) and black locust (Robinia pseudoacacia ), has several pharmacologic activities such as antioxidant, anti-inflammatory, and anti-proliferative effects on cancer cells. However, the effect of acacetin on head and neck cancers has not been clearly established. This study aimed to examine the effects of acacetin on cell growth and apoptosis induction in FaDu human pharyngeal carcinoma cells. These were investigated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay, Live/Dead cell assay, 4′,6-diamidino-2-phenylindole dihydrochloride staining, caspase-3 and caspase-7 activation assay, and immunoblotting in FaDu cells. Acacetin induced FaDu cell death in a dose-dependent manner, with an estimated IC50 value of 41.9 µM, without affecting the viability of L-929 mouse fibroblasts as normal cells. Acacetin treatment resulted in nuclear condensation in the FaDu cells. It promoted the proteolytic cleavage of procaspase-3, -7, -8, and -9 with increasing amounts of the cleaved caspase isoforms in FaDu cells. Acacetin-induced apoptosis in FaDu cells was mediated by the expression of Fas and activation of caspase-8, caspase-3, and poly (ADP-ribose) polymerase. Immunoblotting showed downregulation of the anti-apoptotic mitochondrial proteins Bcl-2 and Bcl-xL, but upregulation of the mitochondria-dependent pro-apoptotic proteins Bax and Badin FaDu cells after acacetin treatment. These findings indicate that acacetin inhibits cell proliferation and induces apoptotic cell death in FaDu human pharyngeal carcinoma cells via both the death receptor-mediated extrinsic apoptotic pathway and the mitochondria-mediated intrinsic apoptotic pathway.
        4,000원
        28.
        2020.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Aluminum (Al) - based powders have attracted attention as key materials for 3D printing because of their excellent specific mechanical strength, formability, and durability. Although many studies on the fabrication of 3Dprinted Al-based alloys have been reported, the influence of the size of raw powder materials on the bulk samples processed by selective laser melting (SLM) has not been fully investigated. In this study, AlSi10Mg powders of 65 μm in average particle size, prepared by a gas atomizing process, are additively manufactured by using an SLM process. AlSi10Mg powders of 45 μm average size are also fabricated into bulk samples in order to compare their properties. The processing parameters of laser power and scan speed are optimized to achieve densified AlSi10Mg alloys. The Vickers hardness value of the bulk sample prepared from 45 μm-sized powders is somewhat higher than that of the 65 μm-sized powder. Such differences in hardness are analyzed because the reduction in melt pool size stems from the rapid melting and solidification of small powders, compared to those of coarse powders, during the SLM process. These results show that the size of the powder should be considered in order to achieve optimization of the SLM process.
        4,000원
        29.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, Al-Si-Mg alloys are additively manufactured using a selective laser melting (SLM) process from AlSi10Mg powders prepared from a gas-atomization process. The processing parameters such as laser scan speed and laser power are investigated for 3D printing of Al-Si-Mg alloys. The laser scan speeds vary from 100 to 2000 mm/ s at the laser power of 180 and 270W, respectively, to achieve optimized densification of the Al-Si-Mg alloy. It is observed that the relative density of the Al-Si-Mg alloy reaches a peak value of 99% at 1600 mm/s for 180W and at 2000 mm/s for 270W. The surface morphologies of the both Al-Si-Mg alloy samples at these conditions show significantly reduced porosities compared to those of other samples. The increase in hardness of as-built Al-Si-Mg alloy with increasing scan speed and laser power is analyzed due to high relative density. Furthermore, it was found that cooling conditions after the heat-treatment for homogenization results in the change of dispersion status of Si phases in the Al-Si matrix but also affects tensile behaviors of Al-Si-Mg alloys. These results indicate that combination between SLM processing parameters and post-heat treatment should be considered a key factor to achieve optimized Al-Si alloy performance.
        4,000원
        30.
        2019.04 구독 인증기관·개인회원 무료
        한국에 서식하는 모기종 중 흔히 볼 수 있는 금빛숲모기(Aedes vexans nipponii)는 미국에서 West Nile Virus의 주요 매개종으로 알려져 있다. 또한 지카바이러스를 포함한 30가지가 넘는 바이러스의 매개체로 작용할 가능성이 있다고 보고되고 있다. 이들을 방제하기 위한 방법으로 화학적 방제는 매우 효과적일 수 있으나 지속적인 살충제 사용은 저항성 문제를 불러일으킬 수 있다. 현재 금빛숲모기의 경우 이에 대한 관련 연구가 거의 이루어지지 않은 상황이다. 본 연구는 근연종인 흰줄숲모기와 이집트숲모기의 연구를 참고하여 합천에 위치한 축사에서 채집된 금빛숲모기 샘플로부터 기존에 알려진 Acetylcholinesterase-1(Ace-1)의 target site mutation인 G119, T506과 knockdown resistance(kdr) target site mutation인 V410, L982, S989, I1011, L1014, V1016, T1520, I1532, F1534, D1763을 분석하였다. 분석결과, 저항성을 가진 개체는 발견되지 않았으며 mutation site에 관해 정확히 알려진 바가 없으므로 bioassay를 통한 추가조사가 필요할 것으로 판단된다.
        31.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to perform the suitability analysis of whole-crop rye (Secale cereale L.) based on the climatic information in the Republic of Korea to present useful information for producers and policy makers to determine the site-selection for the cultivation of the whole-crop rye. The criteria to analyze the climatic suitability of whole-crop rye was developed firstly. Then, the climatic suitability map for spatial analysis was developed through weighted overlaying the raster layers of climatic items in the evaluation criteria. Meanwhile, 16 geographically representative weather stations were selected to show examples of the calculation process of the climatic suitability score of a specific cultivation area. The results of the climatic suitability mapping indicated that the climatic conditions in most arable lands of the Republic of Korea such as the coastal, southern, western areas in the southern region of the Korean Peninsula and central areas in Jeju Island are suitable for the cultivation of whole-crop rye. The climatic suitability scores of the 16 weather stations were all in line with the results of the climatic suitability map.
        4,000원
        32.
        2018.10 구독 인증기관·개인회원 무료
        말라리아는 말라리아원충에 감염된 Anopheles속 모기에 의해 매개되는 질병이다. 한국의 Anopheles속 Hyrcanus group 모기 가운데 특히 Anopheles kleini, Anopheles lesteri, Anopheles pullus는 말라리아 주요 매개충으로 알려져 있다. 한국의 말라리아는 휴전선 인접지역을 중심으로 환자 발생이 지속되고 있으며 이와 더불어 한국의 기후는 점차 아열대 기후로 변화하고 있다. 이러한 기후변화가 한국의 말라리아 전파력에 미치는 영향을 예측하기 위하여 말라리아 위험지역 가운데 경기 서북부 지역인 파주, 김포, 강화 세 지역의 소 축사에서 2014년과 2015년 6월부터 9월까지 채집된 모기의 월별 종 분포를 분석하였으며, 이러한 종 분포와 기후조건과의 관계를 통계분석 하였다. 기후조건으로는 채집일 기준 14일 전까지의 평균기온, 풍속, 강수량, 습도를 이용하였으며 Hyrcanus group 모기 6종(Anopheles belenrae, An. kleini, An. lesteri, An. pullus, Anopheles sinensis, Anopheles sineroides)의 분포를 로지스틱 회귀분석을 통하여 분석하였고, 상관관계를 확인하기 위하여 정준상관분석(Canonical correlation analysis)을 실시하였다. 분석결과, 강수량과의 연관성은 찾지 못하였으나, An. kleini, An. lesteri, An. pullus는 기온이 상승했을 때 Hyrcanus group 내에서의 분포가 증가할 가능성이 있는 것으로 나타났다. 또한 An. sinensis는 풍속과 습도가 높을 경우 증가할 것으로 나타났으며 이를 제외한 나머지 종들은 풍속과 습도가 낮을 경우 증가하는 것으로 나타났다. 이러한 분석 결과를 바탕으로 현재 한반도의 기온이 점점 상승하는 환경은 말라리아 주요 매개충이 서식하기 좋은 환경으로, 기존의 북한과 인접한 DMZ 부근에서 발생하던 말라리아가 한반도 내 다른 지역으로 분포 지역이 확대될 가능성이 있음을 시사한다.
        33.
        2018.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Boron nitride nanotubes (BNNTs) are receiving great attention because of their unusual material properties, such as high thermal conductivity, mechanical strength, and electrical resistance. However, high-throughput and highefficiency synthesis of BNNTs has been hindered due to the high boiling point of boron (~ 4000℃) and weak interaction between boron and nitrogen. Although, hydrogen-catalyzed plasma synthesis has shown potential for scalable synthesis of BNNTs, the direct use of H2 gas as a precursor material is not strongly recommended, as it is extremely flammable. In the present study, BNNTs have been synthesized using radio-frequency inductively coupled thermal plasma (RF-ITP) catalyzed by solid-state ammonium chloride (NH4Cl), a safe catalyst materials for BNNT synthesis. Similar to BNNTs synthesized from h-BN (hexagonal boron nitride) + H2, successful fabrication of BNNTs synthesized from h-BN+NH4Cl is confirmed by their sheet-like properties, FE-SEM images, and XRD analysis. In addition, improved dispersion properties in aqueous solution are found in BNNTs synthesized from h-BN +NH4Cl.
        4,000원
        34.
        2017.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We demonstrated an effective way of preparing melt spinnable mesophase pitches via catalytic hydrogenation of petroleum residue (fluidized catalytic cracking-decant oil) and their subsequent thermal soaking. The mesophase pitches thus obtained were analyzed in terms of their viscosity, elemental composition, solubility, molecular weight, softening point and optical texture. We found that zeolite-induced catalytic hydrogenation under high hydrogen pressure contributed to a large variation in the properties of the pitches. As the hydrogen pressure increased, the C/H ratio decreased, and the solubility in n-hexane increased. The mesophase pitch with entirely anisotropic domains of flow texture exhibited good meltspinnability. The mesophase carbon fibers obtained from the catalytically hydrogenated petroleum residue showed moderate mechanical properties.
        4,000원
        35.
        2017.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, STS316L powders prepared by gas atomization are used to manufacture bulk structures with dimensions of 10 × 10 × 10 mm3 using selective laser melting (SLM). The microstructures and hardness of the fabricated 316L stainless steel has been investigated with the laser beam overlap varied from 10% to 70%. The microstructures of the fabricated STS316L samples show a decrease in the balling and satellite of powders introducing defect in the bulk samples and the porosity caused by the gap between the molten metal pools disappearing as the overlap ratio increases, whereas a low overlap ratio results in significant balling and a large amount of isolated powders due to the increased gap between the melt pools. Furthermore, the highest value in Vickers hardness is obtained for the sample fabricated by 30% overlapped laser beams. These results show that the overlap ratio of laser beams in the SLM process should be considered as an important process parameter.
        4,000원
        36.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A reliable and selective liquid chromatography–ultraviolet detection method for determination of antiprotozoals (selamectin, doramectin and fenbendazol) has been described. HPLC separation of active constituents was achieved on various C18 columns using methanol, acetonitrile, 0.1% phosphoric acid, acetic acid and distilled water as mobile phase, with UV detection at 243, 245 and 224 nm. The analytical procedure has been successfully identified. The method was validated for specificity, linearity, accuracy, repeatability and intermediated precision. All calibration curves showed good linearity (R2 of 0.9999) within the concentrations ranges (0~200, 0~200 and 50~400 μg/mL). The accuracy and repeatability showed 99%, 100%, 100% and below 0.4%, 0.5%, 0.6%, respectively. The precision tests conducted for 3 days in three different concentrations with standard also revealed below 3.5%, 2.4% and 2.7%. The method has also been applied successfully to monitor post-market 5 veterinary products of which active ingredient are selamectin, doramectin and fenbendazol. There were no non-compliant products.
        3,000원
        37.
        2017.04 구독 인증기관·개인회원 무료
        The aim of this study was to use an in vitro method and estimate glycaemic index (GI) from porridges to determine the digestibility of porridges. Glycaemic index’s concept is to classify foods on the basis of their postprandial blood glucose response. The GI of a foodstuff is generally measured by determining the increment in blood glucose concentration after the consumption of a test meal over a set period of time and comparing it with an isoglucosidic control meal (normally white bread or glucose) and expressed as a percentage. In this study, the 5 porridges were studied for their starch digestibility. The available starch contents of the samples varied from 65~85 g/100 g dry solids. From in vitro digestion, the porridge samples were Medium glycaemic index foods with calculated GIs ranging from 56 to 67.
        38.
        2017.04 구독 인증기관·개인회원 무료
        The present paper proposes an categorization of commercial fluid products. A total of 21 commercial fluid products were analyzed(porridges, universal design foods, foods for special medical purposes) corresponding to 11 different commercial brands. Joint consideration has been made of viscous behavior (flow and thixotropy) and viscoelastic behavior (oscillatory testing). Rheological measurements were fitted to different rheological mathematical models, and a total of 4 parameters were generated. Our results correspond to three different classes. The three defined classes have been named in a way similar those most commonly used in the literature. Each class has been defined from the parameters allows us to know the common rheological characteristics of any of the products belonging to a given class.
        39.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This research was conducted to investigate the effects of feeding high and low forage diets with different forage sources on rumen fermentation characteristics and blood parameters of Holstein cows during the dry period. Eight Holstein cows were completely randomized assigned to two groups and repeated measurement was utilized in the analysis. Cows in two treatments were fed with diets with high (F:C = 70:30, 70F; forage source: mixed-sowing whole crop barley and Italian ryegrass silage, BIRG) and low (F:C = 55:45, 55F; forage source: tall fescue hay, TF) forage level. Rumen fluid pH was higher in 70F group. Levels of acetic acid, propionic acid, and butyric acid showed a similar pattern: from the lowest value at 07:30 h to the highest at 10:30 h and then decreased in both groups. The ratio of acetic acid to propionic acid was significantly higher (p < 0.05) in 55F group at 09:30 and 10:30 h. Rumen fluid NH3-N concentrations were significantly higher (p < 0.05) in 70F group at 09:30 and 10:30 h. Blood urea nitrogen was significantly higher (p < 0.05) in 70F group. It was concluded that BIRG based diet with a high forage level had no adverse effects on rumen fermentation, some blood chemical parameters, and immune system in dry Holstein cows and could be used as a forage source instead of imported TF.
        4,000원
        40.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A recent study reported that Pleurotus ostreatus has the potential to be used as a β-glucan-based cream for supportive complementary therapy of atopic dermatitis. KH054 is a new herbal prescription consisting of P. ostreatus and Panax ginseng. The effects of atopic dermatitis-induced materials on the expression of cytokine genes in human monocytes (THP-1, EoL- 1) have been examined. Some reports demonstrated that P. ginseng augments the activity of natural killer cells, which plays an important role in innate immunity against infection and tumor development. Monocyte chemotactic protein 1 (MCP-1), interleukin (IL)-6, and IL-8 have important roles in mediating the infiltration of various cells into the skin of atopic dermatitis and psoriasis. The present study investigated whether KH054 on induced IL-6, IL-8, and MCP-1 secretion by house dust mite (Dermatophagoides pteronissinus) in THP-1 (human acute monocytic leukemia) and EoL-1(Human eosinophilic leukemia) cell. D. pteronissinus functions in the pathogenesis of allergic diseases, including atopic dermatitis and asthma. The inhibitory effect of KH054 on the induction of IL-6, IL-8, and MCP-1 secretion by D. pteronissinus extract in THP-1 and EoL-1 cells was examined. KH054 potently suppressed the elevated production of IL-6 and IL-8 induced by D. pteronissinus treatment in THP-1 and EoL-1 cells. Based on the present results, KH054 may be useful for developing functional foods to treat atopic dermatitis.
        4,000원
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