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        검색결과 134

        62.
        2015.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Powder injection molding is an important manufacturing technology to mass produce superalloy components with complex shape. Injection molding step is particularly important for realizing a desired shape, which requires much time and efforts finding the optimum process condition. Therefore computer aided engineering can be very useful to find proper injection molding conditions. In this study, we have conducted a finite element method based simulation for the spiral mold test of superalloy feedstock and compared the results with experimental ones. Sensitivity analysis with both of simulation and experiment reveals that the melt temperature of superalloy feedstock is the most important factor for the full filling of mold cavity. The FEM based simulation matches well the experimental results. This study contributes to the optimization of superalloy powder injection molding process.
        4,000원
        63.
        2014.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To compensate for the critical shortage of human organs for allotransplantation, xenotransplantation studies using genetically modified pigs are being performed in Korea. Two types of pigs that are used are α1,3-galactosyltransferase gene knockout (GalT KO) pigs and GalT KO+hCD46 (human complement regulatory protein) pigs. The present study measured the gestation time, birth weight, daily growth rate, and heart weight of both kinds of transgenic minipigs. The gestation period for both types of pigs was 117∼119 days. There was no difference in the body weight of GalT KO (—/+) and GalT KO (—/—) piglets, but GalT KO+hCD46 (—hCD46+/+) pigs were significantly heavier at birth than were GalT KO+hCD46 (—hCD46+/—hCD46+) pigs. During the first 10 weeks of life, the daily weight gain of GalT KO+hCD46 (—hCD46+/—CD46+) piglets, which are considered the optimal type for xenotransplantation, was 0.19 kg. The weight of hearts from GalT KO piglets up to two months of age was affected more by body weight than by age. Transgenic pigs showed no differences in gestation period or reproductive ability compared with normal pigs. These results comprise basic data that may be used in xenotransplantation studies and transgenic animal production in Korea.
        4,000원
        68.
        2013.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Star clusters are superb astrophysical laboratories containing cospatial and coeval samples of stars with similar chemical composition. We initiate the Sejong Open cluster Survey (SOS) - a project dedicated to providing homogeneous photometry of a large number of open clusters in the SAAO Johnson-Cousins’ UBV I system. To achieve our main goal, we pay much attention to the observation of standard stars in order to reproduce the SAAO standard system. Many of our targets are relatively small sparse clusters that escaped previous observations. As clusters are considered building blocks of the Galactic disk, their physical properties such as the initial mass function, the pattern of mass segregation, etc. give valuable information on the formation and evolution of the Galactic disk. The spatial distribution of young open clusters will be used to revise the local spiral arm structure of the Galaxy. In addition, the homogeneous data can also be used to test stellar evolutionary theory, especially concerning rare massive stars. In this paper we present the target selection criteria, the observational strategy for accurate photometry, and the adopted calibrations for data analysis such as color-color relations, zero-age main sequence relations, Sp - MV relations, Sp - Teff relations, Sp - color relations, and Teff - BC relations. Finally we provide some data analysis such as the determination of the reddening law, the membership selection criteria, and distance determination.
        5,700원
        70.
        2012.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The current standard solutions for somatic cells used for calibration of electronic somatic cell counts as reference material in raw milk are preserved with bronopol, boric acid, sodium azide, or potassium dichromate, and have a shelf-life of only up to 6 days at 4 ± 2℃. In the present study, a set of somatic cell standard solutions (SCSS) with a stability of 5 months for calibration of electronic instruments was developed. Somatic cells collected from cow’s milk and stored in a bulk tank at a dairy plant were treated with 10% formaldehyde in order to improve stability, and then separated by centrifugation. The resulting somatic cell suspension was preserved with glycerin, thimerosal, and dimethyl sulfoxide, and diluted in 3% processed skim milk solution ranging from 200,000~250,000 (low level), 350,000~ 450,000 (medium level), and 550,000~650,000 (high level) cells/㎖. Each SCSS was verified by direct microscope somatic cell counting (DMSCC), C-reader, and commercial standard samples. The average somatic cell count determined by DMSCC was 248, 214, 226 × 103 cells/㎖, 436, 382, 420 × 103 cells/㎖, and 612, 595, 609 × 103 cells/㎖. The coefficient of variation representing the repeatability of DMSCC decreased as the number of cells increased, and was <10.0% in almost all SCSS samples (range 4.6~7.1%). No statistically significant difference in somatic cell concentration was observed after storage at refrigeration temperature (2~6℃) over a period of 22 weeks (5 months). The stabilized SCSS may be useful as a reference material for determination of somatic cell count and quality control in testing of bovine raw milk.
        4,000원
        71.
        2012.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this study we apply Support Vector Machine (SVM) to the prediction of geo-effective halo coronal mass ejections (CMEs). The SVM, which is one of machine learning algorithms, is used for the purpose of classification and regression analysis. We use halo and partial halo CMEs from January 1996 to April 2010 in the SOHO/LASCO CME Catalog for training and prediction. And we also use their associated X-ray flare classes to identify front-side halo CMEs (stronger than B1 class), and the Dst index to determine geo-effective halo CMEs (stronger than -50 nT). The combinations of the speed and the angular width of CMEs, and their associated X-ray classes are used for input features of the SVM. We make an attempt to find the best model by using cross-validation which is processed by changing kernel functions of the SVM and their parameters. As a result we obtain statistical parameters for the best model by using the speed of CME and its associated X-ray flare class as input features of the SVM: Accuracy=0.66, PODy=0.76, PODn=0.49, FAR=0.72, Bias=1.06, CSI=0.59, TSS=0.25. The performance of the statistical parameters by applying the SVM is much better than those from the simple classifications based on constant classifiers.
        4,000원
        72.
        2011.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        국화과(Compositae)는 현화식물 중 세계에서 가장 넓게 분포하고, 쌍자엽식물 중 가장 진화된 식물분류군이며, 우리나라에는 약 300여종이 존재하는 것으로 알려져 있다. 구절초, 감국, 쑥, 쑥갓, 개미취, 참취, 곰취 등 국화과 식물들은 예로부터 민간에서 약용 및 식용 소재로써 다양하게 사용되어왔다. 본 연구는 국화 및 국화근연종 유용유전자원 선발을 통하여 육종 소재를 확대하고, 중간모본 및 신품종 육성기반을 구축하고자 DNA 마커시스템의 개발을 위해 수행되었다. 1. 화단국인 Smileball(Dendranthema grandiflorum) 품종을 사용하여 SSR-enriched library를 작성하였고, GS FLX 분석을 통해 18.83Mbp의 염기서열 결과를 얻었으며, read의 평균 길이는 280.06bp로 나타났다. 2. 단순반복염기서열(SSR) 부위를 포함하는 26,780개 clones 중 di-nucleotide motifs가 16,375개(61.5%)로 우세하였고, trinucleotide motifs(6,616개, 24.8%), tetra-nucleotide motifs(1,674개, 6.3%), penta-nucleotide motifs(1,283개, 4.8%), hexa-nucleotide motifs(693개, 2.6%) 순으로 나타났다. 3. 얻어진 di-nucleotide motifs들 중에서는, AC/CA class가 93.5%로 대부분이었고, tri-nucleotide motifs에서는 AAC class가 50.5%, tetra-nucleotide motifs는 ACGT class가 43.6%이고, pentanucleotide motif에서는 AACGT class 27.2%이며, hexa-nucleotide motif에서는 ACGATG class 21.8%였다. 4. 얻어진 염기서열 결과를 토대로 다양한 motif를 갖는 100개의 SSR 마커를 제작하였고, 차후 이를 활용하여 국화 유전자원의 다형성 및 유전자형 분석을 통해 분자유전학적 다양성 및 집단의 구조분석이 가능하고, 국화의 분자육종기반 구축을 위한 유용한 도구가 될 것 이다.
        4,000원
        73.
        2011.11 구독 인증기관·개인회원 무료
        This purpose of this study was to analyze the nutritional composition about Auricularia spp., which has been used to Auricularia auricula-judae(black and brown) and Auricularia polytricha. First, the contents of total polyphenol and beta-glucan were analyzed. Subsequently, the contents of free sugars, amino acids and organic acids were analyzed by HPLC. In addition, the content of vitamin D from these strains was also measured and the D3 of this vitamin D was anlyzed. In conclusion, Auricularia spp. showed evident differences in the nutritional composition.
        78.
        2011.05 구독 인증기관·개인회원 무료
        This study was conducted to investigate the physiological activities of the ethanol extracts from 3 different strains of Hericium erinaceum. In addition, the β-glucan and polyphenol contents from these strains were also measured. As a result, total polyphenol contents were the highest in 1ho(39.07 mg%) strain and lowest in 2ho(17.59 mg%). β-glucan contents ranged from 17.69 to 18.26%. In the physiological activities, Inhibition effects of DPPH radical and Nitrite ranged from 3.29 to 9.6% and 1.52 to 5.27%, respectively. Inhibitory effects of nitric oxide production ranged from 23.72 to 33.47%. The highest inhibitory activities on α-amyloglucosidase activity and angiotensin I converting enzyme were 39.30% and 14.10%, respectively. Lastly, the cytotoxic activities of ethanol extracts from all the strains on A549, HT-29 and HeLa cell was shown the highest effect in A549 cell.
        79.
        2010.12 KCI 등재 구독 인증기관·개인회원 무료
        In this study, the anti-oxidant, anti-tumorigenic, anti-hypertensive, anti-thrombic, anti-diabetic, and anti- inflammatory properties of 18 different species of genus Pleurotus were investigated. In addition, the amino acid, β-glucan, and polyphenol contents were also measured. The β-glucan and polyphenol contents were the highest in Pleurotus cornucopiae var. citrinopileatus (yellow Pleurotus) of all species. The yellow Pleurotus also exhibited the highest physiological activity as assessed by the DPPH IC, Cytotoxic activity, ACE activity and so on. To confirm the mechanism for the physiological activity of the yellow Pleurotus, we performed further examinations within ICR mice. The yellow Pleurotus reduced glucose, triglyceride and total cholesterol levels in the ICR mice blood for 4 weeks after feeding, and also significantly lowered both GOT and GPT levels. Taken together, our data indicates the yellow pleurotus is a promising functional food ingredient.
        80.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The phenethyl ester of caffeic acid (CAPE), an active component of honeybee propolis extract, is shown to inhibit cancer growth previously. However, studies on human ovarian cancer are largely obscure. This study evaluated the effects of CAPE as a potenti
        4,000원
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