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        검색결과 2,998

        1561.
        2013.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this study, hydroxyapatite (HAp) was incorporated into toothpaste and its effect on the remineralization and restoration of dental enamel was evaluated. Different sets of toothpaste were incorporated with HAp levels of 0%, 5%, 10 %, and 15 %. The filler particles of the resulting toothpaste samples were observed via SEM and XRD and compared with compositions of several commercially available toothpastes, showing that the HAp was successfully incorporated into the toothpaste samples. Different sets of human enamel were inflicted with lesions and then treated with the different fabricated toothpaste samples for five minutes three times a day for seven days. During the treatment, the teeth were subjected to demineralization and remineralization cycles to simulate the effect of natural saliva. The surface of the enamel samples were observed using SEM before and after one week of treatment, showing the formation of HAp layers on the surfaces of the enamel samples. The effect of the toothpaste on the lesions was observed using an inverted light microscope and the lesion depth was found to decrease as the concentration of HAp in the toothpaste used increased. HAp was successfully incorporated in the toothpaste and its presence was found to lessen lesion depths and improve tooth remineralization.
        4,000원
        1562.
        2013.03 구독 인증기관 무료, 개인회원 유료
        근적외선 흡수 물질은 근적외선 이미징에 사용가능한 물질이며 최근에는 바이오 이미징, 유기태양전지 효율 향상을 목적으로 활용 범위가 확장되고 있다. 근적외선 흡수 물질은 π-conjugation system을 가지고 있으며 전자가 비편재화 되어 밴드갭이 작을수록 장가장 빛을 흡수한다. 주요 물질군으로는 유기 단분자 물질인 Polymethine, Phthalocyanine, Porphyrin 계 물질과 고분자인 Poly(thiophene), Poly(selenophene) 이 있으며, 유기 단분자 소재는 용매에 잘 녹으며 흡수 밴드가 Sharp 하고 고분자 소재는 용매에 잘 녹지 않으며 흡수 밴드가 Broad 한 특징이 있다. 최근 근적외선 응용 관련 분야의 대표적인 선도 연구로는 세포 이미징, 세포치료, 유기태양전지가 있다.
        4,000원
        1563.
        2013.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The effects of heat treatment temperature (HTT) of polyacrylonitrile-based carbon f-ber (CF) on the mechanical, thermal, and tribological properties of C/C composites were investigated. It was found that HTT (graphitization) of CF affects the thermal conductivity and mechanical and tribological characteristics of C/C composites. Thermal treatment of fibersat temperatures up to 2800°C led to a decrease of the wear rate and the friction coefficientof C/C composite-based discs from 7.0 to 1.1 μm/stop and from 0.356 to 0.269, respectively. The friction surface morphology and friction mechanism strongly depended on the mechanical properties of the CFs. The relief of the friction surface of composites based on CFs with finalgraphitization was also modified,compared to that of composites based on initial fibers.This phenomenon could be explained by modificationof the abrasive wear resistance of reinforcement fibersand consequently modificationof the friction and wearing properties of composites. Correlation of the graphitization temperature with the increased flexuraland compressive strength, apparent density, and thermal conductivity of the composites was also demonstrated.
        4,000원
        1564.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, we propose a new re-quantization method after FFT processing to prevent the distortion of correlation result of VCS (VLBI Correlation Subsystem). The re-quantization is used to rearrange the data bit so as to reduce the data rate processed as 16-bit of FFT result of VCS. Having done this procedure, we found that the distorted spectrum of correlation result occurred in the delay tracking experiments by the re-quantization method introduced for initial design of VCS. In order to solve this, two kinds of re-quantization method, that is, the comparison and selection-type, are proposed. The first is to re-quantize the FFT result as a valid-bit by comparing with the input data after determining the adequate threshold. The second is manually to select the valid-bit of FFT result after finding the valid-field of data according to the bit-distribution of input data. We confirmed that the second is more effective compared with the first through the experimental result, and it will be implemented without so much modification of applied method in the condition of the limited resource of FPGA. The re-quantization is, however, carried out with 4-bit in the proposed second method for FFT result, and then the distortion of correlation result is also appeared. To fix this problem, the bit for re-quantization is extended to 8-bit. The proposed 8-bit selection-type is effectively verified so that the distortion of correlation result disappeared by applying to VCS in consequence of the simulation and correlation experiments.
        4,200원
        1565.
        2012.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Inter-granular Bright Points (igBPs) are small-scale objects in the Solar photosphere which can be seen within dark inter-granular lanes. We present a new algorithm to automatically detect and extract igBPs. Laplacian and Morphological Dilation (LMD) technique is employed by the algorithm. It involves three basic processing steps: (1) obtaining candidate "seed" regions by Laplacian; (2) determining the boundary and size of igBPs by morphological dilation; (3) discarding brighter granules by a probability criterion. For validating our algorithm, we used the observed samples of the Dutch Open Telescope (DOT), collected on April 12, 2007. They contain 180 high-resolution images, and each has a 85×68arcsec2 85×68arcsec2 field of view (FOV). Two important results are obtained: first, the identified rate of igBPs reaches 95% and is higher than previous results; second, the diameter distribution is 220±25km 220±25km , which is fully consistent with previously published data. We conclude that the presented algorithm can detect and extract igBPs automatically and effectively.
        4,000원
        1566.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, reduced graphene oxide/polyimide (r-GO/PI) composite films, which showed significant enhancement in their electrical conductivity, were successfully fabricated. GO was prepared from graphite using a modified Hummers method. The GO was used as a nanofiller material for the preparation of r-GO/PI composites by in-situ polymerization. An addition of 20 wt% of GO led to a significant decrease in the volume resistivity of composite films by less than nine orders of magnitude compared to that of pure PI films due to the electrical percolation networks of reduced GO created during imidization within the films. A tensile test indicated that the Young's modulus of the r-GO/PI composite film containing 20 wt% GO increased drastically from 2.3 GPa to 4.4 GPa, which was an improvement of approximately 84% compared to that of pure PI film. In addition, the corresponding tensile strength was found to have decreased only by 12%, from 113 MPa to 99 MPa.
        4,000원
        1567.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was designed to adopt two estrus synchronization protocols in zebu and crossbred heifers and their effects on pregnancy rate after timed artificial insemination (TAI). A number of 120 cyclic heifers were allotted for two different treatment groups and one control group. Heifers under protocol A were injected with GnRH at first day followed by a single dose of at Day 11 and injection of GnRH at the day of AI; and heifers belonged to protocol B were treated with GnRH, two injections at 11 days apart and injection of GnRH at AI. AI was done at fixed time (within 72~96 hours after injection) in both protocols and pregnancy was confirmed by rectal palpation on 80~120 days of post AI. In control group; local heifers were conceived higher (30%) proportion than that of crossbred heifers (25%; p<0.05). In protocol A, the local breed were conceived higher (38.9%) proportion compared with crossbred (25%; p<0.05). In protocol B, local breed heifers were conceived higher (38.9%) proportion compared with crossbred heifers (33.3%; p<0.05). The overall pregnancy rate in protocol A and protocol B was 33.3% and 36.6%, respectively. The proportion of pregnancy rate of local heifers (38.9%; Protocol A) was significant (p<0.05) in comparison with local heifers (30%) in control group (p<0.05). The overall pregnancy rate between pooled control group (28.3%) and treatment group (35%) was significantly (p<0.05) differ from each other's. Results of present study concluded that estrus synchronization followed by fixed time AI could be applied for higher pregnancy rate in zebu and crossbred heifers.
        4,000원
        1568.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        예이츠는 시를 쓰고 편집한다는 것은 알려진 사실이다. 시집 속의 어떤 시 모음은 대체적으로 그 책의 큰 그림 내의 서로의 소통을 보이며, 결국, 시들이 어 떤 시들과 가까이 놓였나를 검토함으로써 독자들의 그 시들에 대한 이해와 감상을 깊 게 한다. 마이클 로바티스와 춤꾼 의 마지막 4편의 시가 분명 그런 경우이며, 어려운 시기에 태어난 사랑하는 딸을 가지는 것에 대한 복잡한 심정으로 고심하는 새 아버지 로서의 예이츠를 보여준다.
        5,100원
        1569.
        2012.12 구독 인증기관 무료, 개인회원 유료
        International academic mobility demands certainty on the academic backgrounds of students, professors, scholars, researchers, experts and consultants. Frequently, institutions and authorities in charge of the recognition of qualifications have installed administrative processes to validate the authenticity of academic credentials and transcripts. This is also the case when it comes to qualification's recognition for professional matters. In some economies, the requisite of the "apostille" and/or the demand for other legalization requirements are seen as a possible route to guarantee authenticity. Still, in the information age, using printed documents might not necessarily be the best way to administer human capital mobility. This paper will discuss an initiative to look into the future in terms of how to improve efficiency and reduce the cost of recognition among the APEC economies: The AsiaPacific Academic Credit and Qualifications Bank.
        4,300원
        1571.
        2012.11 구독 인증기관·개인회원 무료
        Mushroom production by automatic bottle culture system was introduced into China in 1999 and developed rapidly in recent ten years. According to the statistics of Chinese Mushroom Society, about 652 facilities of automatic mechanized bottle system were in 2011. The annual rate of increase of facility is expected to exceed 47%. The gross production by automatic bottle culture system was 990,000 tons in 2011. Beijing Hengdaxing Edible Mushroom Co., Ltd established in 2007 in Tongzhou district, Beijing is a company producing Pleurotus eryngii var. ferulae with annual production of 1,000 tons. The company has finished the technical reformation and expansion. Its designed production capacity is 6.5 tons per day and 2,000 tons per year. Beijing Fuqin Edible Mushroom Science & Technology Co., Ltd is an industrial production company of Flammulina velutipes. It was established in 2007. Its production capacity is 20 tons per day and 7,000 tons per year.