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        검색결과 16

        1.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Military aircraft R&D projects require large-scale investment in cost and time, and involve a complex coordination process in decision-making. The R&D project manager should determine the development management priorities as accurately as possible and focus on R&D capabilities, thereby reducing the risks of the aircraft R&D project. To this end, this study aims to reduce R&D risk by prioritizing cost, schedule, and performance, which are basic management factors used in R&D project management in defense project management regulations. Analytic Hierarchy Process (AHP) is applied using a questionnaire for managers in charge of aviation R&D under the Defense Acquisition Program Administration. As a primary result, the importance of the factors that the aircraft R&D project manager should consider was derived in the order of performance, cost, and schedule, and the priorities of performance and cost in the lower layer were also identified. In addition, in order to provide practical risk management measures to aircraft R&D project managers, the results of analyzing 28 cases of US National Transportation Safety Board accidents were compared and analyzed with the AHP analysis results, and management measures suitable for the situation were specified.
        4,000원
        2.
        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
        3.
        2018.09 구독 인증기관 무료, 개인회원 유료
        Resveratrol (3,4',5,-trihydroxystilbene), a phytoalexin present in grapes, exerts a variety of actions to reduce superoxides, prevents diabetes mellitus, and inhibits inflammation. Resveratrol acts as a chemo-preventive agent and induces apoptotic cell death in various cancer cells. However, the role of resveratrol in odontoblastic cell differentiation is unclear. In this study, the effect of resveratrol on regulating odontoblast differentiation was examined in MDPC-23 mouse odontoblastic cells derived from mouse dental papilla cells. Resveratrol significantly accelerated mineralization as compared with the control culture in differentiation of MDPC-23 cells. Resveratrol significantly increased expression of ALP mRNA as compared with the control in differentiation of MDPC-23 cells. Resveratrol significantly accelerated expression of ColⅠmRNA as compared with the control in differentiation of MDPC-23 cells. Resveratrol significantly increased expressions of DSPP and DMP-1 mRNAs as compared with the control in differentiation of MDPC-23 cells. Treatment of resveratrol did not significantly affect cell proliferation in MDPC-23 cells. Results suggest resveratrol facilitates odontoblast differentiation and mineralization in differentiation of MDPC-23 cells, and may have potential properties for development and clinical application of dentin regeneration materials.
        4,000원
        4.
        2017.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        새우젓갈을 대상으로 젓갈의 품질에 가장 큰 영향을 미치는 식염의 농도 및 숙성 온도가 전체 숙성기간 동안에 식품 위생적 품질 인자의 변화에 미치는 영향을 살펴보았으며, 그 결과는 다음과 같다. 새우젓갈의 휘발성 염기질소 함량은 식염 농도가 높을수록 휘발성 염기질소 함량은 낮게 나타났고, 숙성온도 20oC에서는 10oC에 비해 빠른 휘발성 염기질소 증가를 나타내었다. 또한, 히스타민의 발현은 식염첨가량은 히스타민의 생성에 미치는 영향은 크지 않았으나 숙성온도가 낮은 경우 히스타민의 함량도 낮게 나타나 온도가 히스타민의 발현에 영향을 미치는 인자 임을 확인하였으며, 새우젓갈의 히스타민 함량은 낮은 수준으로 숙성기간 내내 유지되어 새우젓갈에 있어서 히스 타민은 숙성기간을 단축하기 위해 숙성온도를 지나치게 높이지 않는다면 크게 우려하지 않아도 될 것으로 사료된다. 아미노산성 질소함량의 변화는 숙성기간 동안 지속적으로 증가하는 경향을 나타내었으나 숙성온도간 차이에 비해 그 차이는 크지 않았으며, 새우젓갈의 총균수 변화에 미치는 식염 농도 및 숙성온도의 영향은 식염 농도가 높을수록 식염에 의한 미생물의 생육억제 효과가 크게 나타났고, 숙성온도가 낮을수록 총균수도 낮게 나타났으나, 대체로 숙성 30일까지 총균수가 증가하다가 이후 유지 또는 감소하는 경향을 나타내었다. 대장균군 및 대장균의 변화는 원료단계에서 대장균군 및 대장균이 거의 검출되지 않아 이후 숙성동안에도 검출되지 않았다.
        4,000원
        5.
        2017.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This research aimed to improve the healthy properties of puffer fish broth, which has been utilized in Korean and Japanese food. Various healthy foods such as garlic, onion, mushroom, and cauliflower were added as ingredients to pufffer fish stock, and the antioxidative activity of each stock was measured by assaying the DPPH and ABTS radical scavenging activities, reducing power and amount of polyphenol. Shiitake was the most effective in increasing the antioxidative activity of puffer fish stock. The high antioxidative activity of shiitake mushroom seems to be correlated with the amount of polyphenol content in puffer fish broth. The antioxidant activities of puffer fish stock increased proportionally with increasing amount of added shiitake, which in turn was due to the increased amount of total polyphenol in the stock.
        4,000원
        6.
        2017.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to investigate the effect of gelatin concentration and storage on color and texture of puffer fish stock jelly. Puffer fish stock jelly was prepared by adding various amounts (2.5~10 percent) of gelatin to puffer fish stock. Color changes of puffer fish sstock jelly were also investigated during storage at 4℃ and 25℃ with varying amount of gelatin (2.5~10.0 percent). Regardless of storage temperature, the L values of puffer fish stock jelly were slightly increased, while a values of the stock jelly were negatively decreased during storage. However, L and negative b values were decreased with increasing gelatin concentration, whereas a values were increased negatively with increasing gelatin concentration. The texture profiles of puffer fish stock jelly such as hardness, springiness, cohesiveness adhesiveness, chewiness and brittleness were determined during storage at 25℃ and 4℃ at various intervals. The hardness, chewiness and brittleness were increased during storage at 25℃ for four days, while those of springiness and cohesiveness were decreased during storage. However, the values of all textural parameters were increased with increasing gelatin concentration in puffer fish stock jelly. Patterns of textural parameters of puffer fish stock jelly stored at 4℃ were practically identical to those stored at 25℃.
        4,000원
        7.
        2017.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Effect of salt concentration (10, 20 and 30%, respectively) and fermentation temperature (10 and 20oC, respectively) on changes in quality index (VBN, Histamine, Amino nitrogen, Total viable cell counts, Coliform bacteria and E. coli counts) of culinary salted and fermented anchovy during fermentation were investigated to suggestion of fundamental documents for industrial objectives. Our results show that the effect of salt concentration on changes in quality index was not high compared with fermentation temperature in salted and fermented anchovy with below 20% of salt concentration however effect of salt concentration and fermentation temperature on quality index was not significant with 30% salt concentration. And all most whole changes of quality index were rapidly increased or decreased for 30 days of fermentation.
        4,000원
        8.
        2013.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Size-sorted graphene nanoplatelets are highly desired for fundamental research and technological applications of graphene. Here we show a facile approach for fabricating size-sorted graphene oxide (GO) nanoplatelets by a simple centrifugal method using different dispersion solvents. We found that the small-sized GO nanoplatelets were more effectively separated when dispersed in water or dimethylformamide (DMF) than in an alkali aqueous solution. After several iterations of the centrifugation, the sizes of GO in the supernatant solution were mostly several micrometers. We found that the GO area was not strongly correlated with the C-O content of the GO dispersed in water. However, the size-sorted GO nanoplatelets in DMF showed different C-O content, since DMF can reduce GO nanoplatelets during exfoliation and centrifugation processes.
        4,000원
        9.
        2007.12 구독 인증기관 무료, 개인회원 유료
        Single-walled carbon nanotubes (SWNTs)를 320 ℃에서 90분 동안 가열하여 비정질 탄소를 제거하고 남아 있는 금속 촉매를 제거하기 위해 염산에 24시간 처리하였다. 정제된 SWNT 표면에 산화반응을 통해 카복실기를 도입하였으며, 가혹한 환경으로 인해 길이가 짧아진 SWNT를 얻었다. 세정된 실리콘 웨이퍼를 3-aminopropyldiisopropylethoxysilane (3-APDIPES)의 톨루엔 용액에 담가 표면에 3-APDIPES의 자기 조립 단층막을 형성시켰다. SWNT의 카복실기와 3-APDIPES의 아미노기 사이의 산-염기 반응을 통해 생성되는 이온 사이의 정전기적 인력을 이용하여 실리콘 웨이퍼 표면에 SWNT를 배열하였다. Atomic Force Microscopy (AFM) 분석을 통해 반응시간과 농도에 따른 효과를 확인하였고, Transmission Electron Microscopy (TEM)을 이용해 산 처리 시간에 따른 효과를 확인하였다.
        4,000원
        10.
        2012.03 KCI 등재 서비스 종료(열람 제한)
        The purpose of this paper is to investigate Discourse Markers (DMs) used by NNETs (non-native English Teacher) and NETs (native English Teacher). DMs play a significant role in communication to develop ideas and to relate them to one another. Four sub-objectives of the present study were: (1) How do non-native English teachers differ from native English teachers in their most frequent use of DMs (2) What is the most frequently used DM and how frequently does it occur in both groups, (3) What are the prevailing functions of the DMs employed in both groups, and (4) What are the implications for teaching L2 learners and the training of Korean English teachers? The encoded DMs offer a reservoir of DMs from six NETs and NNETs teachers` DM usages when teaching in class. The data were based on the video recorded data analysis performed by six NETs and six NNETs at a Korean university. First, they were analyzed by the Statistical Package for the Social Sciences (SPSS), and then classified according to Brinton`s (1996) inventory of items and Schiffrin`s (1987) classification. It is concluded that both NNETs and NETs more frequently consider coherent discourse by using DMs in an interactive situation that requires speakers to draw upon communicative knowledge and pragmatic resources. This may be because NNETs and NETs have different normative pragmatics (Sellars, 1969) of language. Therefore, more research and attention should be redirected to DMs to emphasize pragmatic use of English in teachers` training programs.
        15.
        2006.01 KCI 등재 서비스 종료(열람 제한)
        The simultaneous analysis of multi-residual pesticides was developed using a gas chromatography (GC) method. In this study, a simple and reliable methodology was improved to detect 154 kinds of pesticides in ginseng extract sample by using a liquid-liquid extraction procedure, open column chromagraphy and chromatographic analysis by GC electron capture detector (ECD) and GC nitrogen-phosphorus detector (NPD). The 154 kinds of pesticides were classified in 4 groups according to the chemical structure. The extraction of pesticides was experimented with 70% acetone and dichloromethane/petroleum ether in order, and cleaned up via open column chromatography (3×30㎝) packed with florisil (30g, 130℃, 12hrs). The final extract was concentrated in a rotator evaporator at 40℃ until dryness. Then the residue was redissolved to 2㎖ with acetone, and analyzed by GC-ECD and GC-NPD. The applied concentration of pesticides was over 1~10㎍/㎖. The recovery tests were ranged from 70.7% to 115.2% with standard deviations between 0.3 and 5.7% of the standard spiked to the ginseng extract sample (Group Ⅰ~Ⅳ). The limit of detection (LOD) ranged from 0.001 to 0.099㎍/㎖ (Group Ⅰ~Ⅳ). The 9 kinds of pesticides were not detected. The developed method was applied satisfactory to the determination of the 154 kinds of pesticides in the ginseng extract with good reproducibility and accuracy.
        16.
        2004.12 KCI 등재 서비스 종료(열람 제한)
        This study was investigated the residual contents of sulfur dioxide on the 373 kinds of herbal medicine distributed from Korea, China, and Japan. A modified Monier-Williams method was described for the determination of SO2 contents in herbal medicines. The residual contents of SO2 were not detected at 221 products(59.8%) in total 373 products. Regardless of region, SO2 contents were not found at Farfarae Flos, Zizyphi Spinosi Semen, Castanea crenata, and Strychni Ignatii Semen. But it's found at Asparagi Radix, Codonopsitis Radix, Lilii Bulbus, and Kaempferiae Rhizoma of every region collected the samples. Also, SO2 contents were not detected at the herbal medicines which collected cultural fields of dometic. SO2 contents ranged 11~3990 mg/kg(mean 152 mg/kg) at domestic samples, 11~3440 mg/kg(mean 603 mg/kg) at imported samples. After treated with water wash and hot water extraction, the reduction rates of sulfur dioxide were appeared with 24.4%~68.7% and 83.8%~100.0%, respectively. These data will be used to establish a criteron of residual sulfur dioxide in herbal medicines.