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        검색결과 436

        201.
        2013.09 구독 인증기관 무료, 개인회원 유료
        Transgenic chickens have been spotlighted as an highly potent bioreactor for their fecundity, short generation time, and eggs associated with mass production of protein. In this study, we generated transgenic chickens exhibiting oviduct specific expression of human growth hormone fused to human transferrin for oral administration. Gene of the modified growth hormone located at downstream ovalbumin promoter (∼3.6 kb) was introduced to stage X blastodermal cell employing retrovirus vector system. Several transgenic chickens were successfully generated. However, genomic analyses showed unexpected deletion within the transgene. The modification of the transgene seemed to occur during germ cell formation because the deletion was detected only from the sperm DNA of the G0 founder animal. There was no evidence of deletion in the somatic cell DNA samples of the same chicken. Consequently, same pattern of the deletion was confirmed in both somatic and germ cells of the G1 progeny.
        4,000원
        202.
        2013.09 구독 인증기관 무료, 개인회원 유료
        소듐 2-브로모에탄술포네이트를 이용한 2-에티닐피리딘의 무촉매중합을 통하여 새로운 이온성 폴리아세틸렌을 합성하였다. 중합반응은 균일하게 진행되었으며 높은 수율 (중합수율: 78%)로 해당고분자를 합성하였다. 반응 초기 사차 염화과정에서 생성된 활성화 N-(에틸술포네이트 소듐)-2-에티닐피리디늄 브로마이드가 중합반응의 단량체로 참여하고 있는 것으로 밝혀졌다. 고분자의 분자 구조를 여러 가지 분석기기로 확인한 결과 설계한 치환기를 갖는 폴리아세틸렌 유도체가 합성되었음을 확인할 수 있었다. 합성 고분자의 고유점도는 0.12-0.15 dL/g 범위였으며 X-선 회절분석 결과 무정형상임을 확인할 수 있었다. 고분자의 광발광 피크가 593 nm에서 관찰되었는데, 이는 2.09 eV의 광에너지에 해당한다. 이 고분자는 도핑과 탈도핑 피크 사이에서 비가역 전기화학적 거동을 보였다.
        4,000원
        203.
        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
        206.
        2013.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to determine the reliability and validity of the postural balance program which uses the movement accelerating field principles of posture balance training and evaluation equipment and smartphone movement accelerometer program (SMAP) in healthy young adults. A total of 34 people were appointed as the subject among the healthy young adults. By using Biodex stability system (BSS) and SMAP on the subject, the posture balance capability was evaluated. For the test-retest reliability, SMAP showed the intra-class correlation (ICC: .62~.91) and standard error measurement (SEM: .01~.08). BSS showed the moderate to high reliability of ICC (.88~.93) and SEM (.02~.20). In the reliability of inter-rater, ICC (.59~.73) as to SMAP, showed the reliability of moderate in eyes open stability all (EOSA), eyes open stability anterior posterior (EOSAP), eyes open stability medial lateral (EOSML) and eyes open dinamic all (EODA), eyes open danamic anterior posterior (EODAP), and eyes open danamic medial lateral (EODML). However, ICC showed reliability which was as low as .59 less than in other movements. In addition, BSS showed the reliability of high as ICC (.70~.75). It showed reliability which was as low as ICC (.59 less than) in other movements. In correlation to the balance by attitudes between SMAP and BSS, EOSML (r=.62), EODA (r=.75), EODML (r=.72), ECDAP (r=.64), and ECDML (r=.69) shown differ significantly (p<.05). However, the correlation noted in other movements did not differ significantly. Therefore, SMAP and BSS can be usefully used in the posture balance assessment of the static and dynamic condition with eyes opened and closed.
        4,000원
        210.
        2013.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study assesses of efficiency of oocyte recovery and in vitro development for during the non breeding season in goat. Thirty-four matured goats, maintained in a pen under natural day length and fed hay ad libitum, were pretreated with progestagen implanted CIDR for 10 days. Superovulation treatment of the goats received twice daily intramuscular injections of a total of 70 mg FSH for 3 days from Day 8 of CIDR. All the gonadotropin treated goats were injected with 10 mg PGF2α on Day 8 and 400~600 IU hCG in the afternoon on Day 10. Oocytes were recovered by follicle aspiration or oviduct flushing at 35 to 40 h after hCG injection through mid-ventral incision. The in vivo matured oocytes were activated by ionomycin (5 min) and 6-DMAP (3.5~4 h). The activated oocytes were cultured in mSOF medium containing 0.8% BSA at 38.5℃ in an atmosphere of 5% CO2, 5% O2, 90% N2 for 7~8 days. There was no significant difference in the mean number of CL and in vivo matured and follicular oocytes recovered. But, quality of I+II grade follicular oocytes was lower (p<0.05) in the prepubertal goat (25.0%) than the adults (52.4%). The same results were also observed in the cleavage and blastocyst rate of activated oocytes. The clavage and blastocyst rate from prepubertal derived oocytes were lower (p<0.05) in the prepubertal goat (54.5%, 23.3%) than the adult goat (86.8%, 46.6%). Considering overall these results, we suggest that maturation of donor goats is a major factor affecting recovered oocytes quality and in vitro development of activated goat oocytes. There was no significant difference in oocyte quality between seasonal treatments.
        4,000원
        211.
        2013.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        태국에의 옥수수 재배는 종자 가격의 상승, 잦은 기후변화, 때때로 부족한 종자로 인하여 종자구입을 주저하고 있는 실정인데, 종자의 자가소비 및 이웃농가 보급을 통하여 옥수수 종자구입 비용의 절감을 목적으로, 태국 농업청(Department of Agriculture, Thailand)과 한국 농촌진흥청(Rural DevelopmentAdministration, Republic of Korea)과의 협력으로 AFACI(Asian Food and Agriculture Cooperation Initiative)의 태국 국별 과제로 옥수수 종자마을 조성(Maize Seed Village) 사업을 선정하여 추진하였다. 대상 품종은 태국 자체 육성종인 건조저항성 단교잡종 나콘사완3(Nakhon Sawan 3)로 교잡종 채종기술은 나콘사완전작물연구소가 운영한 채종농가 훈련을 거쳐 이전되었으며 이를 위하여 종자채종기술 교재 600부를 제작 활용하였다. 2010 여름, 2011 우기, 2011 여름 기간, 총 3작기에 걸쳐 5개주 52개 마을 175농가 96 ha에서 종자 79,988kg을 생산하여 자가 소비 및 이웃 농가 보급에 활용하였다. 생산된 종자의 판매가격은 일반 상업화 종자 가격의 46~60%수준이었으며, 농가는 나콘사완 3 교잡 종자에 대한 채종재배기술과 품종의 성능에 크게 만족하였다.
        4,000원
        212.
        2012.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This study examined whether vocabulary knowledge has meaningful effects on reading comprehension of Korean high school EFL learners and investigated which specific type of vocabulary knowledge, between vocabulary breadth and depth, plays a bigger role in reading comprehension when the learners’ English language proficiency is taken into account. The participants of this study were ninety eight high school EFL learners in Seoul, Korea, and they were tested on a series of measures tapping on their reading comprehension abilities and vocabulary knowledge in two different dimensions (vocabulary breadth and depth). Their listening comprehension abilities were also measured in order to control for the effects of general oral language comprehension abilities known to be the foremost contributor to reading comprehension and thus to enable focused analysis of the role of vocabulary knowledge. The study findings revealed that 1) vocabulary knowledge itself played a critical role in predicting reading comprehension abilities even after controlling for their listening comprehension abilities and that 2) compared to vocabulary breadth, vocabulary depth played a relatively more important role in predicting reading comprehension, regardless of the learners’ language proficiency. The findings provide important implications for vocabulary and reading comprehension instructions for Korean EFL students.
        6,000원
        213.
        2012.12 구독 인증기관 무료, 개인회원 유료
        The technique of SCNT is now well established but still remains inefficient. The in vitro development of SCNT embryos is dependent upon numerous factors including the recipient cytoplast and karyoplast. Above all, the metaphase of the second meiotic division (MII) oocytes have typically become the recipient of choice. Generally high level of MPF present in MII oocytes induces the transferred nucleus to enter mitotic division precociously and causes NEBD and PCC, which may be the critical role for nuclear reprogramming. In the present study we investigated the in vitro development and pregnancy of White-Hanwoo SCNT embryos treated with caffeine (a protein kinase phosphatase inhibitor). As results, the treatment of 10 mM caffeine for 6 h significantly increased MPF activity in bovine oocytes but does not affect the developmental competence to the blastocyst stage in bovine SCNT embryos. However, a significant increase in the mean cell number of blastocysts and the frequency of pregnant on 150 days of White-Hanwoo SCNT embryos produced using caffeine treated cytoplasts was observed. These results indicated that the recipient cytoplast treated with caffeine for a short period prior to reconstruction of SCNT embryos is able to increase the frequency of pregnancy in cow.
        4,000원
        215.
        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
        216.
        2012.06 구독 인증기관 무료, 개인회원 유료
        The use of high throughput screening (HTS) in drug development is principally for the selection new drug candidates or screening of chemical toxicants. This system minimizes the experimental environment and allows for the screening of candidates at the same time. Umbilical cord-derived stem cells have some of the characteristics of fetal stem cell and have several advantages such as the ease with which they can be obtained and lack of ethical issues. To establish a HTS system, optimized conditions that mimic typical cell culture conditions in a minimal space such as 96 well plates are needed for stem cell growth. We have thus established a novel HTS system using human umbilical cord derived-mesenchymal stem cells (hUC-MSCs). To determine the optimal cell number, hUC-MSCs were serially diluted and seeded at 750, 500, 200 and 100 cells per well on 96 well plates. The maintenance efficiencies of these dilutions were compared for 3, 7, 9, and 14 days. The fetal bovine serum (FBS) concentration (20, 10, 5 and 1%) and the cell numbers (750, 500 and 200 cells/well) were compared for 3, 5 and 7 days. In addition, we evaluated the optimal conditions for cell cycle block. These four independent optimization experiments were conducted using an MTT assay. In the results, the optimal conditions for a HTS system using hUC-MSCs were determined to be 300 cell/well cultured for 8 days with 1 or 5% FBS. In addition, we demonstrated that the optimal conditions for a cell cycle block in this culture system are 48 hours in the absence of FBS. In addition, we candidates using our HTS system which demonstrates the feasibility if using hUC-MSCs for this type of screen. Moreover, the four candidate compounds can be tested for stem cell research application.
        4,000원
        217.
        2012.06 구독 인증기관·개인회원 무료
        The generation and application of porcine iPSCs (piPSCs) as a large animal model may enable the test for the efficacy and safety of the therapy in the field of human regenerative medicine. Here, we report the generation of piPSC from wild (a 10-day-old Massachusetts General Hospital miniature pig; MGH minipig) and genetically modified pig, alpha1,3-Galactosyltransferase knock-out (—/—) (GalT KO homo) and human CD46 (membrane cofactor protein) knock-in (hCD46 KI) MGH minipig (a 10-day-old). Fibroblasts were isolated from the ear skin of wild and MGH minipigs, respectively. After 2 passages, each of fibroblasts was transduced with cocktail of 6 human factors (POU5F1, NANOG, SOX2, C-MYC, KLF4, and LIN28) and cultured on a mitotically inactive mouse embryonic fibroblast (MEF) monolayer. Both of reprogrammed somatic cells expressed the classical pluripotency markers (POU5F1, NANOG, and SOX2) and surface marker (SSEA1). Similar to mouse ESCs, both piPSCs from wild and transgenic minipigs were negative for SSEA3, Tra-1-60, and Tra-1-81. Further these cells could form embryoid body (EB) and differentiate into 3 germ layers in vitro (ectoderm: FOXJ3 and PAX6, mesoderm: HAND2, and endoderm: SOX17 and GATA6). Our piPSCs may provide useful source as a large animal model for studying approaches that can reduce an immune- rejection of cell or organ transplantation.
        218.
        2012.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Fe-based self-fluxing alloy powders and TiC particles were ball-milled and subsequently compacted and sintered at various temperatures, resulting in the TiC particle-reinforced Fe self-fluxing alloy hybrid composite, and the microstructure and micro-hardness were investigated. The initial Fe-based self-fluxing alloy powders and TiC particles showed the spherical shape with a mean size of approximately 80 and the irregular shape of less than 5 , respectively. After ball-milling at 800 rpm for 5 h, the powder mixture of Fe-based self-fluxing alloy powders and TiC particles formed into the agglomerated powders with the size of approximately 10 that was composed of the nanosized TiC particles and nano-sized alloy particles. The TiC particle-reinforced Fe-based self-fluxing alloy hybrid composite sintered at 1173 K revealed a much denser microstructure and higher micro-hardness than that sintered at 1073 K and 1273 K.
        4,000원
        219.
        2012.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Mass production of graphene-based materials, which have high specific surface area, is of importance for industrial applications. Herein, we report on a facile approach to produce thermally modified graphene oxide (TMG) in large quantities. We performed this experiment with a hot plate under environments that have relatively low temperature and no using inert gas. TMG materials showed a high specific surface area (430 m2g-1). Successful reduction was confirmed by elemental analysis, X-ray photoelectron spectroscopy, thermogravimetic analysis, and X-ray diffraction. The resulting materials might be useful for various applications such as in rechargeable batteries, as hydrogen storage materials, as nano-fillers in composites, in ultracapacitors, and in chemical/bio sensors.
        3,000원
        220.
        2011.12 구독 인증기관 무료, 개인회원 유료
        The experimental manipulation of protooncogenes and their gene products is a valuable research tool for the study of human neoplasia. In this study, the recently identified human cervical cancer protooncogene (HccR-2) was expressed in transgenic mice under the control of the tetracycline regulatory system. The phenotype observed was similar in many respects to human chronic neutrophilic leukemia (CNL). Thus, the HccR-2 transgenic mouse model is important not only for investigating the biological properties of the HccR-2 protooncogene in vivo, but also for analyzing the mechanisms involved in the progression of CNL.
        4,000원