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        검색결과 143

        82.
        2008.10 구독 인증기관·개인회원 무료
        This study was conducted to improve the effect of environment-friendly Tetranychus urticae pesticide through the development of Tetranychus urticae biopesticide using the plant extract. Tested extracts were fig leaf extract, viburnum erosum extract; besides Sophora flavescens Ait extract, Derris root extract, Tobacco leaf extract, and they were proved to be the caricidal effect of two spotted spider mite adults by spraying on the French bean leaf inoculated for Tetranychus urticae with each concentration; 500ppm, 200ppm, 100ppm, 50ppm. In the control treatments, caricidal effect was compared with only ‘Eungsami’ (500ppm, 200ppm, 100ppm, 50ppm), of which the main ingredient as environment-friendly organic material is, and distilled water. The caricidal effect of tested extracts to the two spotted spider mite adult was the highest in the Sophora flavescens Ait extract and Tobacco leaf extract over 90%, and comparatively low in the Derris root extract. When the caricidal effect of ‘Eungsami’ was compared with two spotted spider mite adults with each concentration, ‘Eungsami’(500ppm) and Tobacco leaf extract(500ppm) were very excellent as each 95.5%, 98.7% in treated concentration. The effect of Sophora flavescens Ait extract was also high as 96.5%. In the low concentration(50ppm), Sophora flavescens Ait extract was 45.8%, Tobacco leaf extract was the most effective as 53.8%.
        83.
        2008.06 구독 인증기관 무료, 개인회원 유료
        The endogenous retrovirus-like elements (HERVs) found on several human chromosomes are somehow involved in gene regulation, especially during the transcription level. HERV-H, located on chromosome Xp22, may regulate gastrin-releasing peptide receptor (GRPR) in connection with diverse diseases. By suppression subtractive hybridization screen on SV40-immortalized lung fibroblast (WI-38 VA-13), we discovered that expression of HERV-HX2, a clustered HERV-H sequence on chromosome X, was upregulated in immortalized lung cells, compared to that of normal cells. Expression of HERV-HX2 was then analyzed in various cell lines, including normal somatic cells, cancer cells, SV40-immortalized cells, and undifferentiated and differentiated human embryonic stem cells. Expression of HERV-HX2 was specifically upregulated in continuously-dividing cells, such as cancer cells and SV40-immortalized cells. Especially, HERV-HX2 in HeLa cells was highly upregulated during the S phase of the cell cycle. Similar results were obtained in hES cells, in which undifferentiated cells expressed more HERV-HX2 mRNA than differentiated hES cells, including neural precursor and endothelial progenitor cells. Taken together, our results suggest that HERV-HX2 is upregulated in cancer cells and undifferentiated hES cells, whereas downregulated as differentiation progress. Therefore, we assume that HERV-HX2 may playa role on proliferation of cancer cells as well as differentiation of hES cells in the transcriptional level.
        4,000원
        84.
        2008.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We have investigated the optical properties of the global haze on Titan from spectra recorded between 7100 and 9200Åwhere CH4 absorption bands of various intensities occur. The Titan spectra were obtained on Feb. 23, 2005 (UT), near the times of the Cassini T3 flyby and Huygens probe, using an optical echelle spectrograph (BOES) on the 1.8-m telescope at Bohyunsan Observatory in Korea. In order to derive the optical properties of the haze as a function of altitude, we developed an inversion radiative-transfer program using an atmospheric model of Titan and laboratory CH4 absorption coefficients available from the literature. The derived extinction coefficients of the haze increase toward the surface, and the coefficients at shorter wavelengths are greater than those at longer wavelengths for the 30 - 120 km altitude range, indicating that the Titanian haze becomes optically thin toward the longer wavelength range. Total optical depths of the haze are estimated to be 1.4 and 1.2 for the 7270 -7360Åand 8940 -9150Å ranges, respectively. Based on the Huygens/DISR data set, Tomasko et al. (2005) reported total optical depths of 2.5 - 3.5 at 8290Å depending on the assumed fractal aggregate particle model. The total optical depths based on our results are smaller than those of Tomasko et al., but they partially overlap with their results if we consider a large uncertainty from possible variations of the CH4 mixing ratio over Titan's disk. We also derived the single scattering albedo of the haze particles as a function of altitude: it is less than 0.5 at altitudes higher than ~150Km the average particle radius is smaller than the wavelengths, whereas near the surface, it becomes comparable or greater.
        4,300원
        87.
        2004.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ixeris dentata is a typical oriental herb. It is a widely distributed perennial in Korea, Japan and China, which belongs to the Compositae Family. The whole plant of I. dentata has been used for the treatment of pneumonia, contusion, tumor and hepatitis.
        4,000원
        88.
        2004.12 구독 인증기관 무료, 개인회원 유료
        Human embryonic stem (ES) cells are derived from the inner cell mass of the preimplantation embryo. Human ES cells have the capacity to differentiate into various types of cells in the body. Human ES cells are indefinite source of cells for cell therapy in various degenerative disorders including neuronal disorders. Directed differentiation of human ES cells is a prerequisite for their clinical application. The objective of this study is to develop the culture condition for the derivation of neural precursor cells from human ES cells. Neural precursor cells were derived from human ES cells in a stepwise culture condition. Neural precursor cells in the form of neural rosette structures developed into neurospheres when cultured in suspension. Suspension culture of neurospheres has been maintained over 4 months. Expressions of nestin, soxl, sox2, pax3 and pax6 transcripts were upregulated during differentiation into neural precursor cells by RT-PCR analysis. In contrast, expression of oct4 was dramatically downregulated in neural precursor cells. Immunocytochemical analyses of neural precursor cells demonstrated expression of nestin and SOX1. When induced to differentiate on an adhesive substrate, neuro-spheres were able to differentiate into three lineages of neural systems, including neurons, astrocytes and oligo-dendrocytes. Transcripts of sox1 and pax6 were downregulated during differentiation of neural precursor cells into neurons. In contrast, expression of map2ab was elevated in the differentiated cells, relative to those in neural precursor cells. Neurons derived from neural precursor cells expressed NCAM, Tuj1, MAP2ab, NeuN and NF200 in immunocytochemical analyses. Presence of astrocytes was confirmed by expression of GFAP immuno-cytochemically. Oligodendrocytes were also observed by positive immuno-reactivities against oligodendrocyte marker O1. Results of this study demonstrate that a stepwise culture condition is developed for the derivation of neural precursor cells from human ES cells.
        4,000원
        96.
        2018.11 KCI 등재 서비스 종료(열람 제한)
        관망의 해석은 관망의 설치, 운영에서 매우 중요한 요소이다. 이를 위한 연구 방법은 1차원 모형과 3차원 모형이 있으나 각각은 정확도와 계산속도의 면에서 관망 해석에 장점과 한계점을 보인다. 2차원 모형의 경우 1차원 모형과 달리 난류 점성을 이용하여 보다 정확한 마찰을 모의할 수 있게 하는데, 이때 사용되는 난류 점성을 모의하는 모형은 Five-Region Turbulence Model을 이용하였다. 그러나 이들 모형에 사용되는 매개 변수들은 실험에 의한 값이기 때문에 이러한 매개변수에 따른 2차원 부정류 해석 방법의 응답 특성을 알아보았다. 이를 위해 실제 상수관망에서의 수격압 데이터와 부정류 해석 모형으로 부터의 수격압 데이터를 비교하고, 다양한 매개변수에 따른 속도 분포 모의 특성을 조사하였다. 이를 통해서, 난류 해석 모형의 마찰 거동과 매개변수와의 관계를 규명하였다.
        97.
        2018.09 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        본 연구는 완주에서 재배된 세계 주요 11개 적포도 품종으로 제조된 적포도주의 향기 성분을 headspace-solid phase microextraction 분석법으로 확인하였다. 향기성분은 총 75종이 확인되었다. 아로마화합물은 그들의 OAV 값에 의해 5 그룹으로 나뉘었다. 알콜, 알데하이드, 에스테르, C6 화합물이 11개 적포도주의 주요한 향기성분이었다. Isoamy alcohol 알콜과 phenylethyl 알콜은 11개 포도주에서 공통적으로 꽃향기, 달콤한 향을 나타내는데 중요한 물질이었다. Octanoic acid, ethyl ester, hexanoic acid ethylester은 모든 레드와인에서 과실향과 꽃향, 달콤한 향을 내는 중요한 성분이었다. 1-Hexanol은 모든 포도주에서 분석되었으나 풀향을 나타내는 향으로 나타났다. Chanceller, Malbec, marchel, Nsrsha, Pinot Meunier, Sangiovetto 포도주의 주요 향기성분은 과실 향인 것으로 나타났으며 Cabernet Franc, Cabernet Sauvignon, Sauvignon Vert 포도주의 주요 향기성분은 풀향인 것으로 조사되었다. 또한, MBA와 Narsha 포도주의 경우 꽃향이 주요 향인 것으로 조사되었다. 본 연구 결과를 바탕으로 적포도주용 품종을 육성할 때 선발기준으로 향기성분 분석을 활용할 수 있을 것으로 판단되었다.
        98.
        2018.04 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        The study compared the juice and wine odorants of the Cheongsoo grape cultivar with those of Chardonnay and Reisling wines. The volatile compounds of the three grape varieties were analyzed using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry. The most common volatile compounds in the juices from the three cultivars were terpenes, C13-norisoprenoids, etones, alcohols, and aldehydes. Terpenes were established as the most abundant group of volatiles in Cheongsoo grape juice, where as aldehydes predominated in Chardonnay and Riesling juices. Forty-two volatile compounds (acids, alcohols, esters, and others) were detected in the three white wines. The concentration of esters was about four times higher in Cheongsoo wine than in Chardonnay and Riesling wines. Five esters found in the Cheongsoo wine, namely, isoamyl acetate, ethyl butanoate, ethyl hexanoate, ethyl octanoate, and ethyl decanoate, exhibited high odor activity values (OAV) of >1. Furthermore, only Cheongsoo wine had a high OAV for isoamyl acetate odorant, which is associated with banana and sweet aromas. Therefore, the abundant and varied esters are believed to be key volatile fruity/sweet odorants in Cheongsoo wine.
        99.
        2017.11 서비스 종료(열람 제한)
        There is a rising interest of depletion of deposited fossil fuel and environmental pollution, inducing extensive studies to find new alternative sustainable energy sources to replace current petroleum based energy usage. As one of solutions, anaerobic digestion (AD) treating organic wastes has been considered one of the most promising processes owing to its sustainability, low production of sludge, unnecessariness of aeration, and biogas generation. Swine wastewater is characterized by high strength of organic matter contents, so it is regarded as a potential feedstock to produce methane through AD process. To investigate the functional relationship between the microbial communities and anaerobic process performance, regular seasonal sampling was done at four full scale anaerobic digesters treating swine wastewater in South Korea for two years. As results of process and microbial community analyses, chemical oxygen demand (COD) removal efficiency was monitored to proportional to those of carbohydrates, proteins and lipids. Methanogenic and bacterial populations were also positively related to the removal efficiencies of carbohydrates and lipids. However, proteins removal efficiency was independent of microbial population. It means that microbial communities in full scale anaerobic digesters are most likely to be mainly associated with carbohydrates and/or lipids metabolisms, indicating that proteins may be putative recalcitrant contents in wastewater. The microbial population tends to be more affected by places rather than seasons; however, with respect to seasons, the highest species abundances were observed mainly at winter. This implied that rising temperature in the anaerobic digesters in summer would be not suitable for the growth of mesophilic microorganisms, known to be predominant in anaerobic process. Actually, this speculation is supported by the fact that the highest removal efficiency of COD was measured at winter samples. The marked information in this study must provide a real insight into the effective field operation of anaerobic digestion.
        100.
        2017.02 KCI 등재 서비스 종료(열람 제한)
        This paper presents the development of a 3D printer based piezo-driven vertical micro-positioning stage. The stage consists of two flexure bridge structures which amplify and transfer the horizontal motion of the piezo-element into vertical motion of the end-effector. The stage is fabricated with ABS material using a precision 3D printer. This enables a one-body design eliminating the need for assembly, and significantly increases the freedom in design while shortening fabrication time. The design of the stage was optimized using response surface analysis method. Experimental results are presented which demonstrate 100nm stepping in the vertical out-of-plane direction. The results demonstrate the future possibilities of applying 3D printers and ABS material in fabricating linear driven motion stages.
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