검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 509

        101.
        2012.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Morphological control on hydroxyapatite crystals has attractive prospects in research to clarify the effects of crystal planes on biological performance. Hydrothermal processing is known as a typical type of processing for fabricating well-grown crystals with unique morphology. The purpose of the present study is to examine the feasibility of well-crystallized crystals with oriented structures through hydrothermal treatment of calcite. A single crystal of calcite was applied to hydrothermal treatment in a phosphate solution at 160˚C. Rod-shaped hydroxyapatite crystals with micrometer-size were formed on the 100 face of calcite after treatment, while nanometer-sized hydroxyapatite crystals were formed on the (111). The hydroxyapatite crystals formed on each plane were not morphologically changed with increasing treatment periods. An oriented structure of rod-shaped hydroxyapatite was constructed after hydrothermal treatment of 100 planes on the calcite single, while such orientation was not observed on the (111) plane after the treatment. The layer of hydroxyapatite formed on the 100 plane was thicker than that of the (111) plane. The 100 plane of calcite shows a higher reactivity than that of the (111) plane, which results in rapid crystal growth of hydroxyapatite. The difference in the morphology of the formed hydroxyapatite was governed by the reactivity of each crystal plane exposed to the surrounding solution.
        4,000원
        102.
        2012.08 구독 인증기관·개인회원 무료
        Time runs at a constant speed twenty four hours per day and seven days a week. However ancient poets of Korea, China, and Japan had sung songs that time had run at different speeds according to the situations of the poets. The poets of the three countries had visualized agony, 'Han(恨),' and hope according to the slow and fast flows of time. They had sung human limitations not to control the flows of time and importance of present time with rises and falls of human lives. 'BaiJuyi' sang songs combining into time and human lives in 'Chang-Han-Ka' and 'Bi-Pa-Hang.' 'Chang-Han-Ka' describes the love of King, 'Xuanzong,' and 'Yang Guifei,' a royal concubine; the tragic death of her; his yearning, sorrow, 'Han,' and hope for the lost in the flows of time. ‘漢皇重色思傾國’, ‘天旋地轉迴龍馭’,‘春風桃李花開日’ ‘秋雨 梧桐落葉時’, ‘悠悠生死別經年’, ‘昭陽殿裏恩愛絶’ ‘蓬萊宮中日月長’, ‘天長地久 有時盡,’ and ‘此恨緜緜無絶期’ are typical poetic expressions about them. 'Bi-Pa-Hang' describes the miserable stories of a relegated poet 'BaiJuyi' and the sad stories of a woman who was an excellent harp player but finally became a wife of an old merch ant in the flows of time. ‘千呼萬喚始出來’, ‘今年歡笑復明年’,‘秋月春風 等閑度,’ ‘暮去朝來顔色故,’ ‘門前冷落鞍馬稀’, ‘老大嫁作商人婦,’ ‘終歲不聞絲 竹聲,’ and ‘春江花朝秋月夜’are typical poetic expressions about those. There is no literature having no connection with time. Literature is expressions of happiness and sadness which happen in the flows of time. Therefore, it is important to understand the meaning of time in Chinese poetry. In order to teach Chinese poems, one must understand the slow and fast flows of time which were embedded in them.
        103.
        2012.08 구독 인증기관·개인회원 무료
        This paper examine Korean word written in Chinese character about thedifferences of meaning with Chinese vocabulary. To do this work, I used Korean dictionary which is called 《PyoZunKukAweDaeSaZun標準國語大詞典》published by Korean government and Baidu internet cite. The scope of usage and application of Korean word written in Chinese character especially in this 《PyoZunKukAweDaeSaZun標準國語大詞典》is limited than Chinese vocabulary usage. And it is not easy for Korean people to use Korean word written in Chinese character easily. Now, many Korean classic that is written in classical chinese are translated into korea language. It is the time that 《PyoZunKukAweDaeSaZun標準國語大詞典》have to adopt the Korean word written in Chinese character which is in Korean classic as an example of usage. And then this dictionary will be more abundant to use. It also solve many difficulties for korean people to learn how toapply Korean word written in Chinese character in Korean language. After restriction on the use of Korean word in Chinese word after 1945, Korea still have many obstacles to use Korean word written in Chinese character as an government official document. More important thing is that 《PyoZunKukAweDaeSaZun標準國語大詞典》needs more supplement explanation. And the reference of Chinese and classical chinese vocabulary explanation is very helpful to find out its usage and meaning. If 《PyoZunKukAweDaeSaZun標準國語大詞典》adopt new way, it is also possible for Korean to understand Korean classics more easily and correctly.
        104.
        2012.07 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Two types of nanoclusters, termed Cluster (1) and Cluster (2) here, both play an important role in the age-hardening behavior in Al-Mg-Si alloys. Small amounts of additions of Cu and Ag affect the formation of nanoclusters. Two exothermic peaks were clearly detected in differential scanning calorimetry(DSC) curves by means of peak separation by the Gaussian method in the base, Cu-added, Ag-added and Cu-Ag-added Al-Mg-Si alloys. The formation of nanoclusters in the initial stage of natural aging was suppressed in the Ag-added and Cu-Ag-added alloys, while the formation of nanoclusters was enhanced at an aging time longer than 259.2 ks(3 days) of natural aging with the addition Cu and Ag. The formation of nanoclusters while aging at 100˚C was accelerated in the Cu-added, Ag-added and Cu-Ag-added alloys due to the attractive interaction between the Cu and Ag atoms and the Mg atoms. The influence of additions of Cu and Ag on the clustering behavior during low-temperature aging was well characterized based on the interaction energies among solute atoms and on vacancies derived from the first-principle calculation of the full-potential Korrinaga-Kohn-Rostoker(FPKKR)-Green function method. The effects of low Cu and Ag additions on the formation of nanoclusters were also discussed based on the age-hardening phenomena.
        4,000원
        105.
        2012.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To investigate the biochemical nature of changes in vaginal physiology during estrus and pregnancy, we examined the cytology and viscosity, and monitored the protein expression profile in vaginal mucus during estrus and pregnancy. The viscosity progressively decreased from estrus to pregnancy. Cell type analysis revealed that white blood cells progressively increased from estrus to pregnancy, while red blood cells progressively decreased during pregnancy. The cornification index (CI) was higher in estrus than in pregnancy. Protein mass spectrumetry identified the presence of ribosome-binding protein 1, GRIP 1 (Glutamate receptor-interacting protein 1)-associated protein 1, DUF729 (Domain of unknown function729) domain-containing protein 1, prolactin precursor, dihydrofolatereductase, and MMP (Matrix metalloprotease)-9 in vaginal mucus. MMP-2 and MMP-9 proteins in the vaginal mucus were active throughout estrus and gestation, as measured by a gelatinase assay, but most abundant in the vaginal mucus on day 0 of estrus. Results from ELISA of MMP-2 and MMP-9 were in accordance with the gelatinase assay. In light of the crucial role of metalloproteinases in extracellular matrix remodeling, the level of MMP-9 in vaginal mucus might be useful as an indicator of estrus and pregnancy to increase the efficiency of reproduction.
        4,000원
        106.
        2012.06 구독 인증기관 무료, 개인회원 유료
        We identified cdf based on screening of the Arabidopsis cDNA library for functional suppressors of the AtBI-1 (a gene described to suppress the cell death induced by Bax gene expression in yeast). The cdf was located on Chr. V and was composed of 5 exons and 4 introns. It encodes a protein of 258 amino acid residues with a molecular weight of 28.8 kDa. The protein has 3 transmembrane domains in the C-terminal region. The cdf has one homologue, named cdf2, which was found in Arabidopsis. Like cdf, cdf2 also induced growth defect in yeast. The effect of the cell growth defect factor was somewhat lower than Bax. cdf could arrest the growth of yeast. Its localization to the nucleus was essential for the suppression of yeast cell proliferation. Morphological abnormality of intracellular network, which is a hallmark of AtBI-1, was attenuated by expression of cdf.
        4,200원
        107.
        2012.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Fe doped TiO2 nanoparticles were prepared under high temperature and pressure conditions by mixture of metal nitrate solution and TiO2 sol. Fe doped TiO2 particles were reacted in the temperature range of 170 to 200˚C for 6 h. The microstructure and phase of the synthesized Fe doped TiO2 nanoparticles were studied by SEM (FE-SEM), TEM, and XRD. Thermal properties of the synthesized Fe doped TiO2 nanoparticles were studied by TG-DTA analysis. TEM and X-ray diffraction pattern shows that the synthesized Fe doped TiO2 nanoparticles were crystalline. The average size and distribution of the synthesized Fe doped TiO2 nanoparticles were about 10 nm and narrow, respectively. The average size of the synthesized Fe doped TiO2 nanoparticles increased as the reaction temperature increased. The overall reduction in weight of Fe doped TiO2 nanoparticles was about 16% up to ~700˚C; water of crystallization was dehydrated at 271˚C. The transition of Fe doped TiO2 nanoparticle phase from anatase to rutile occurred at almost 561˚C. The amount of rutile phase of the synthesized Fe doped TiO2 nanoparticles increased with decreasing Fe concentration. The effects of synthesis parameters, such as the concentration of the starting solution and the reaction temperature, are discussed.
        3,000원
        108.
        2012.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The effect of Al addition on the precipitation behavior of a binary Mg-Zn alloy was investigated based on thechanges in the morphology, distribution and element concentration of precipitates formed during aging treatment. The as-castMg-6.0 mass%Zn (Mg-6Zn) and Mg-6.0 mass%Zn-3.0 mass%Al (Al-added) were homogenized at 613K for 48h and at 673Kfor 12h; they were then solid solution treated at 673K for 0.5 h and 1 h, respectively. The Mg-6Zn and Al-added alloys wereaged at 403 K and 433K. The peak hardness of the Al-added alloy was higher than that of the Mg-6Zn alloy at each agingtemperature. Rod-like, plate-like, blocky, and lath-like precipitates were observed in the Al-added alloy aged at 433K for230.4ks, although the rod-like and plate-like precipitates were observed in the TEM microstructure of the Mg-6Zn alloy agedat 433K for 360 ks. Moreover, the precipitates in the Al-added alloy were refined and densely distributed compared with thosein the Mg-6Zn alloy. The Cliff-Lorimer plots obtained by the EDS analysis of the rod-like and plate-like phases in theAl-added alloy peak aged at 433K for 230.4ks were examined. It was confirmed that the phases had higher concentrationof solute Al atom than was present in the phases, indicating that the properties of precipitates can be changed by Al addition.
        4,000원
        109.
        2011.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Mammalian fertilization is a complex cascade process consisting of sperm migration through the female reproductive tract, physiological changes to sperm such as sperm capacitation and acrosome reaction, and sperm-egg interaction in the oviduct in vivo. On the other hand, in vitro fertilization (IVF) is a process by which egg cells are fertilized by sperm outside the body: in vitro. IVF has been used for a variety of purposes in reproductive biotechnology for human and animals. The discovery of sperm capacitation in 1951 promoted the development of IVF technology. In the initial stage of IVF, sperm capacitation in preincubation medium was shown to be essential to fuse with eggs. Besides, sperms should detour some of the in vivo regulations for IVF. This review introduces a general mammalian fertilization process, including sperm capacitation, removal of cumulus matrix, acrosome reaction, and sperm-egg fusion and focuses on the roles of key biochemical molecules, signal mechanisms, and genes involved during IVF and novel results of sperm-oocyte interaction elucidated in various gene-knockout mice models.
        4,000원
        110.
        2011.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ski protein is implicated in proliferation/differentiation in a variety of cells. We had previously reported that Ski protein is present in granulosa cells of atretic follicles, but not in preovulatory follicles, suggesting that Ski has a role in apoptosis of granulosa cells. The alternative fate of granulosa cells other than apoptosis is to differentiate to luteal cells, however, it is unknown whether Ski is expressed and has a role in granulosa cells undergoing luteinization. Thus, the aim of the present study was to examine whether the initiation of luteinization with luteinizing hormone (LH) directly regulates expression of Ski in the luteinized granulosa and luteal cells after ovulation by in vitro models. RT-PCR and real time PCR analysis respectively revealed that LH had no effect on c-Ski mRNA expression in the cultured granulosa cells regardless of LH treatment. Though Ski protein is absent in granulosa cells of preovulatory follicle, its mRNA (c-Ski) was expressed and the level was unchanged even after LH surge. Taken together, these results demonstrated that Ski protein expression is induced in granulosa cells upon luteinization, and suggested that its expression is regulated post-transcriptionally. Moreover, expression of mRNA of Arkadia, an E3 ubiquitin ligases, in luteinizing granulosa cells in vivo was assessed by realtime-PCR. The levels of Arkadia mRNA expression were unchanged during follicular growth and postovulatory luteinization. These findings suggest that Ski protein level may be regulated during luteinization at translational and/or post-translational level but not by Arkadia.
        4,000원
        111.
        2011.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Sloan-Kettering virus gene product of a cellular protooncogene c-Ski is an unique nuclear pro-oncoprotein and belongs to the Ski/Sno proto-oncogene family. Ski plays multiple roles in a variety of cell types, it can induce both oncogenic transformation and terminal muscle differentiation when expressed at high levels. Ski protein is implicated in proliferation/differentiation in a variety of cells. The alternative fate of granulosa cells other than apoptosis is to differentiate to luteal cells, however, it is unknown whether Ski is expressed and has a role in granulosa cells undergoing luteinization. Thus, the aim of this study was, by means of immunohistochemical methods, to locate Ski protein in the rat ovaries during ovulation and corpora lutea (CL) formation to predict the possible involvement of Ski in luteinization. In addition, we performed to examine whether the initiation of luteinization with luteinizing hormone (LH) directly regulates expression of Ski in the luteinized granulosa and luteal cells after ovulation by in vivo models. In order to examine the expression pattern of Ski protein along with the progress of luteinization, follicular growth was induced by administration of equine chorionic gonadtropin to immature female rat, and luteinization was induced by human chorionic gonadtropin treatment to mimic luteinizing hormone (LH) surge. While no Ski-positive granulosa cells were present in preovulatory follicle, Ski protein expression was induced in response to LH surge, and was maintained after the formation of corpus luteum (CL). These results indicate that Ski is profoundly expressed in the luteinized granulosa cells and luteal cells of CL during luteinization, and suggest that Ski may play a role in luteinization of granulosa cells.
        4,000원
        112.
        2011.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The preparation of Y2O3-doped ZrO2 nanoparticles in Igepal CO-520/cyclohexane reverse micelle solutions is studied here. In this work, we synthesized nanosized Y2O3-doped ZrO2 powders in a reverse micelle process using aqueous ammonia as the precipitant. In this way, a hydroxide precursor was obtained from nitrate solutions dispersed in the nanosized aqueous domains of a microemulsion consisting of cyclohexane as the oil phase, with poly (oxyethylene) nonylphenylether (Igepal CO-520) as the non-ionic surfactant. The synthesized and calcined powders were characterized by thermogravimetrydifferential thermal analysis (TGA-DTA), X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). The crystallite size was found to nearly identical with an increase in the water-to-surfactant (R) molar ratio. A FTIR analysis was carried to monitor the elimination of residual oil and surfactant phases from the microemulsion-derived precursor and the calcined powder. The average particle size and distribution of the synthesized Y2O3-doped ZrO2 were below 5 nm and narrow, respectively. The TG-DTA analysis showed that the phase of the Y2O3-doped ZrO2 nanoparticles changes from the monoclinic phase to the tetragonal phase at temperatures close to 530˚C. The phase of the synthesized Y2O3-doped ZrO2 when heated to 600˚C was tetragonal ZrO2.
        4,000원
        113.
        2011.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        As homework, a total of 32 seventh grade science-gifted students were asked to observe the moon at daily intervals for one month duration. They were also asked to take the photos and to record relevant variables in a given format. The purpose of the task was to investigate what students thought, as they observed the moon. The results show that students paid attention mainly to the position of the moon relative to other variables such as the date in the lunar calendar, the observer's position on the earth, and the position of the sun. Overall students' response implied that students did not observe the lunar phase in relation with relevant variables. Some reponses from students show common misconceptions such as the cause of the lunar phase to reflect the shadow of the earth. However, some responses reveal students' idea that has been rarely reported in the previous researches. For example, some students drew the moon to revolve in the opposite direction. Significant number of students drew the sun's position to be due west before the full moon and due east after the full moon. Few students recognized the relation between the time of observation and observer's position on the earth. The results of current research suggest that not only the education but also the research needs to be expanded to consider informal environment such as the actual field conditions.
        4,000원
        114.
        2011.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Tin (IV) dioxide (SnO2) has attracted much attention due to its potential scientific significance and technological applications. SnO2 nanoparticles were prepared under low temperature and pressure conditions via precipitation from a 0.1 M SnCl4·5H2O solution by slowly adding NH4OH while rapidly stirring the solution. SnO2 nanoparticles were obtained from the reaction in the temperature range from 130 to 250˚C during 6 h. The microstructure and phase of the synthesized tin oxide particles were studied using XRD and TEM analyses. The average crystalline sizes of the synthesized SnO2 particles were from 5 to 20 nm and they had a narrow distribution. The average crystalline size of the synthesized particles increased as the reaction temperature increased. The crystalline size of the synthesized tin oxide particles decreased with increases in the pH value. The X-ray analysis showed that the synthesized particles were crystalline, and the SAED patterns also indicate that the synthesized SnO2 nanoparticles were crystalline. Furthermore, the morphology of the synthesized SnO2 nanoparticles was as a function of the reaction temperature. The effects of the synthesis parameters, such as the pH condition and reaction temperature, are also discussed.
        3,000원
        115.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we examined the effectiveness of in vitro fertilization of porcine immature oocytes on the embryo development of blastocysts or hatched blastocysts and the number of cells according to the in vitro fertilization conditions. In the in vitro fertilization of in vitro matured porcine oocytes, there were no significant differences between treatment groups regarding fertilization rate, blastocyst rate, and embryo development of hatched blastocysts according to the storage periods of liquid sperm of 24, 48, and 72 hours. The embryo development rate of hatched blastocysts after the fertilization according to different spermatozoa concentrations (, , and cells/ml) showed the highest rate in the group with a spermatozoa concentration of cells/ml; in particular, this rate was significantly higher than that in the cells/ml group (p<0.05). The total number of blastocysts cells as well as trophectoderms (TE) that developed in each treatment group were also significantly higher in the cells/ml group than in any other groups (p<0.05). In contrast, the embryo development rate of blastocysts according to different co-incubation periods of sperm and oocyte (1, 3, and 6 hr) was high in the 6-hour group; in particular, the rate was significantly higher than that of the I-hour group (p<0.05). Furthermore, the total number of oocytes cells and TEs that developed was significantly higher in the 6-hour group than any other group (p<0.05). In this study, the most effective treatment conditions for porcine embryo development and high cell number were found to be as follows: a sperm storage period of less than 72 hours, a spermatozoa concentration of cells/ml, and a 6-hour co-incubation period for sperm and ooocyte.
        4,000원
        116.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In general, zona pellucida (ZP) of the blastocyst has to be removed first, then either isolated the inner cell mass (ICM) or ZP-removed whole blastocyst, which is then cultured on the feeder layer to induce ICM outgrowth for the generation of embryonic stem cells (ESC). However, it is unclear whether ICM isolation before seeding on feeder layer is beneficial or not because the interaction between ICM and trophoblasts may affect cellular growth and/or pluripotency during the culture on the feeder. In the present study, two ZP removal methods (mechanically by splitting with a 28-gauge needle versus chemically by the treatment of acid-Tyrode's solution) and two ICM isolation methods (ZP-free whole blastocyst seeding versus mechanical isolation of ICM) were evaluated for the efficient isolation and culture of putative parthenogenetic bovine ESC. The number of maintained outgrown colonies was counted in each experimental group. As the result, mechanical removal of ZP with a needle and followed by whole ZP-free blastocyst seeding on feeder cells tended to attach more on the feeder layer and resulted in more outgrown colonies with its simple and less time-costing benefits. Currently we are generating ESC lines in HanWoo cattle by using this method for initial outgrowth of the parthenogenetic bovine blastocysts.
        4,000원
        117.
        2011.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Perovskite manganites such as RE1-xAxMnO3 (RE = rare earth, A = Ca, Sr, Ba) have been the subject of intense research in the last few years, ever since the discovery that these systems demonstrate colossal magnetoresistance (CMR). The CMR is usually explained with the double-exchange (DE) mechanism, and CMR materials have potential applications for magnetic switching, recording devices, and more. However, the intrinsic CMR effect is usually found under the conditions of a magnetic field of several Teslas and a narrow temperature range near the Curie temperature (Tc). This magnetic field and temperature range make practical applications impossible. Recently, another type of MR, called the low-field magnetoresistance(LFMR), has also been a research focus. This MR is typically found in polycrystalline half-metallic ferromagnets, and is associated with the spin-dependent charge transport across grain boundaries. Composites with compositions La0.7(Ca1-xSrx)0.3MnO3)]0.99/(BaTiO3)0.01 [(LCSMO)0.99/(BTO)0.01]were prepared with different Sr doping levels x by a standard ceramic technique, and their electrical transport and magnetoresistance (MR) properties were investigated. The structure and morphology of the composites were studied by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). BTO peaks could not be found in the XRD pattern because the amount of BTO in the composites was too small. As the content of x decreased, the crystal structure changed from orthorhombic to rhombohedral. This change can be explained by the fact that the crystal structure of pure LCMO is orthorhombic and the crystal structure of pure LSMO is rhombohedral. The SEM results indicate that LCSMO and BTO coexist in the composites and BTO mostly segregates at the grain boundaries of LCSMO, which are in accordance with the results of the magnetic measurements. The resistivity of all the composites was measured in the range of 90-400K at 0T, 0.5T magnetic field. The result indicates that the MR of the composites increases systematically as the Ca concentration increases, although the transition temperature Tc shifts to a lower range.
        3,000원