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        검색결과 343

        61.
        2012.03 구독 인증기관 무료, 개인회원 유료
        The recent progressive collapse analysis method of structures assumes the threat-independent removal of vertical load-carrying elements. In reality, a blast-induced column-missing event will produce the damage on adjacent structural elements and the rapid dynamic response of the structures. In this study, the strain rate effects on the dynamic collapse behavior of blast-damaged steel moment frames are investigated by performing the blast-induced sequential progressive collapse analysis of a three-storey steel moment frame.
        4,000원
        62.
        2011.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Procymidone is a fungicide with anti-androgenic properties widely used to protect fruits from fungal infection, which induces an excessive reactive oxygen species production in male reproductive organs. In this study, to clarify whether procymidone affect the cellular antioxidant system of prostate at onset of puberty, gene expression patterns of the representative antioxidant enzymes such as cytoplasmic glutathione peroxidase (GPx1), phospholipid hydroperoxide GPx (PHGPx), selenoprotein P (SePP), cytoplasmic copper/zinc superoxide dismutase (SOD1), and manganese SOD (SOD2) were investigated in the rat ventral prostates exposed to procymidone using real-time RT-PCR analyses. Seven-week-old Sprague-Dawley rats castrated at 6 weeks old were treated with procymidone (25, 50, or 100 mg/kg per day) orally for 7 consecutive days after testosterone propionate (0.4 mg/kg per day) administration by subcutaneous injection. As compared to normal control animals, GPx1 mRNA expression in prostates significantly increased by the administration with TP and/or procymidone. However, PHGPx and SOD1 mRNA levels significanatly decreased by over 25 mg/kg of procymidone treatment and SePP and SOD2 mRNA levels was significanatly reduced by over 50 mg/kg of procymidone treatment. These findings indicate that procymidone may affect the antioxidant system of prostatic cells in up-regulation mode of GPx1, but in down-regulation modes of PHGPx, SePP, SOD1, and SOD2, suggesting that procymidone may affect differently the cellular antioxidant system of prostate according to the exposure doses.
        4,000원
        63.
        2011.11 KCI 등재 구독 인증기관·개인회원 무료
        개인정보의 보호에 관한 종래의 논의는 행정의 공정성‧투명성‧신뢰성의 확보 및 국민권익의 보장을 목적으로 하는 행정절차의 실현과정에서 제기된 것이다. 행정절차는 국민의 행정참여를 도모하여 행정의 민주화‧적정화‧능률화를 꾀하려는 데 그 목적이 있는 바, 여기서 행정청을 포함한 공공기관과 대등한 위치에 당사자로서의 국민을 설정하기 위해공공기관이 보유한 행정정보의 활용은 필수적이라 할 수 있다. 그러나 관련기관에 행정정보를 제공하거나 이용토록 하기도 하고 행정정보를 직접 국민에게 공표하도록 하면서 오히려 그 개념상 개인정보를 포함할 수밖에 없는 행정정보의 활용에 대한 적절한 제한설정이 요구되게 된 것이다. 그리하여 적절한 행정절차에 부차적으로 기능하던 기존의 행정상 정보공개 및 정보보호 제도가 정보사회를 수렴하는 행정정보에 관한 규범으로 체계화되기에 이르렀다. 그와 같은 배경에는 전자정부의 출범요인인 정보기술의 발전은 개인정보를 통합 관리할 수 있게 함으로써 오히려 디지털화된 개인정보의 유출 가능성을 증폭시키고 있다는 점과 전자정부의 구현원리이자 운영원칙인 행정정보의 공개 및 공동이용은 대상정보의 성격상 개인정보보호와 상충될 수 있다는 점이 관여한다. 따라서 헌법상 알 권리‧행정수요‧개인정보의 보호가치가 모순되지 아니하도록 관련 법규범의 조화로운 적용과 실천적인 운용이 요청된다고 할 것이다.이와 같은 관점에서 이 글에서는 컴퓨터시스템과 네트워크를 활용한 방법으로 정보전달의 신속성‧정확성 확보, 지리적‧시간적 한계의 극복, 종이문서사용의 절감 등의 효과를 유발하는 행정정보의 공동이용 및 범죄예방이라는 공익적 목적을 수행하기 위하여 폐쇄회로텔레비전을 운용함으로써 경찰인력의 소모를 감쇄시킬 수 있는 화상정보의 수집이라는 행정정보의 활용이 지니는 역기능으로서 개인정보에 관한 정보주체의 권리제한의 적합성에 관해 살펴보기로 한다. 지난 해 5월 5일부터 시행된 「전자정부법」은 행정정보 공동이용의 범위를 확장하고 있는 반면 지난 9월 30일부터 시행된 「개인정보 보호법」은 영상정보처리기기의 운용에 관한 제한을 설정하면서도 정보주체의 권리보장을 명시하고 있기에 상호 충돌된 가치에 있으므로 그 향방이 주목될 뿐 아니라 두 쟁점 모두 개인정보를 포함하는 행정정보 활용에 관한 것이기에, 결국 헌법상 일반원칙에 부합하고 개인정보의 보호에 관한 국제기준에 부합하는지에 대하여 실질적으로 되짚어보아야 하기 때문이다. 이 글은 이와 관련하여 위 두 법률의 상호관련성에서의 바람직한 개정방향의 단초를 짚어보아 개인정보자기결정권 보장에 관한 헌법합치적 법제도를 타진해본다.
        65.
        2011.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        5,700원
        66.
        2011.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The stress-strain responses and oxidation properties of cold-rolled Zr-1.5Nb-O and Zr-1.5Nb-O-S alloys were studied. The U.T.S. (ultimate tensile strength) of cold-rolled Zr-1.5Nb-O-S alloy with 160 ppm sulfur (765 MPa) were greater than that of Zr-1Nb-1Sn-0.1Fe alloy (750 MPa), achieving an excellent mechanical strength even after the elimination of Sn, an effective solution strengthening element. The addition of sulfur increased the strength at the expense of ductility. However, the ductile fracture behavior was observed both in Zr-Nb-O and Zr-Nb-O-S alloys. The beneficial effect of sulphur on the strengthening was observed in the cold rolled Zr-1.5Nb-O-S alloys. The activation volume of cold-rolled Zr-1.5Nb decreased with sulfur content in the temperature region of dynamic strain aging associated with oxygen atoms. Insensitivity of the activation volume to the dislocation density and the decrease of the activation volume at a higher temperature where the dynamic strain aging occurs support the suggestion linking the activation volume with the activated bulge of dislocations limited by segregation of oxygen and sulfur atoms. The addition of sulfur was also found to improve the oxidation resistance of Zr-Nb-O alloys.
        4,000원
        68.
        2011.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this study, the heat flow of the plant scale aluminum extrusion process was investigated to establish optimum continuous heat treatment conditions. During the extrusion of 6061 aluminum alloy, processing parameters such as the extrusion pressure, speed and temperature histories of billets were logged as a function of time. The surface temperature of the billets increased at constant ram speed, while it decreased with decreases of the ram speed. In order to maintain the billet temperature within a solutionizing temperature range prior to the succeeding water quenching step, the ram speed or the temperature of the blower should be controlled. The temperature histories of the billets during the extrusion and hot air blowing processes were successfully simulated by using the velocity boundary model in ANSYS CFX. The methodology to design an optimum process by using a commercial simulation program is described in this study on the basis of the metallurgical validation results of the microstructural observation of the extrudates. The developed model allowed the advantages of taking into account the motion of the extrudate coupled with the temperature change based on empirical data. Calculations were made for the extrudate passing through the isothermal chamber maintained at appropriate temperature. It was confirmed that the continuous heat treatment system is beneficial to the productivity enhancement of the commercial aluminum extrusion industry.
        4,000원
        71.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was to evaluate the protein profile of seminal plasma using 2-DE in Hanwoo. Seminal plasma was harvested from five mature Hanwoo, and seminal plasma protein was extracted by M-PER Mammalian Protein Extraction Reagent. Proteins were refined by clean-up kit and quantified by Bradford method until total protein was . Immobilized pH gradient (IPG) strip was used 18 cm and 3~11 NL. SDS-PAGE was used 12% acrylamide gel. Each gels were visualized by comassie brilliant blue and silver staining. These spots were analyzed by MALDI-TOF MS and searched on NCBInr. The result, 20 proteins of 36 protein spots were searched through peptide sequencing on the NCBInr. 8 proteins profiled by 2-DE were proved through previous bovine studies and the name of each protein was albumin, nucleobindin, clusterin, TIMP-2, spermadhesin Z13, spermadhesin-1 and BSP proteins (BSP 30 kDa and BSP A1/A2). 12 new proteins were ATP synthase, protein MAK16 homolog, Transmembrane protein 214, E3 ubiquitin-protein ligase BRE1A, dual serine/threonine and tyrosine protein kinase, tissue factor pathway inhibitor 2, alpha-actinin-4, RUN domain-containing protein 3B, catenin alpha-1, protein-glutamine gamma-glutamyltransferase 2, plakophilin-1 and inter-alpha-trypsin inhibitor heavy chain H1 has not been previously described in the bovine seminal plasma study. These proteins may be contribute to define the type of proteins affecting fertility of male and improve the fertilizing ability of semen in Hanwoo.
        4,000원
        73.
        2010.11 구독 인증기관 무료, 개인회원 유료
        3,000원
        74.
        2010.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purposes of this case study were (1) to explore one experienced teacher's views on Earth Systems Education and (2) to describe and document the characteristics of the Earth Systems Education (ESE) curriculum provided by an exemplary middle school science teacher, Dr. J. All the essential pieces of evidence were collected from observations, interviews with the experienced teacher and his eighth grade students, informal conversations, document analysis, and field notes. The NUD*IST for MS Windows was used for an initial data reduction process and to narrow down the focus of an analysis. All transcriptions and written documents were reviewed carefully and repeatedly to find rich evidence through inductive and content analysis. The findings revealed that ESE provided a conceptual focus and theme for organizing his school curriculum. The curriculum offered opportunities for students to learn relevant local topics and to connect the classroom learning to the real world. The curriculum also played an important role in developing students' value and appreciation of Earth systems and concern for the local environment. His instructional strategies were very compatible with recommendations from a constructivist theory. His major teaching methodology and strategies were hands-on learning, authentic activities-based learning, cooperative learning, project-based learning (e.g., mini-projects), and science field trips. With respect to his views about benefits and difficulties associated with ESE, the most important benefit was that the curriculum provided authentic-based, hands-on activities and made connections between students and everyday life experiences. In addition, he believed that it was not difficult to teach using ESE. However, the lack of time devoted to field trips and a lack of suitable resource materials were obstacles to the implementation of the curriculum. Implications for science education and future research are suggested.
        5,700원
        75.
        2010.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        A series of molecular dynamic (MD), finite element (FE) and ab initio simulations are carried out to establish suitable modeling schemes for the continuum-based analysis of aluminum matrix nanocomposites reinforced with carbon nanotubes (CNTs). From a comparison of the MD with FE models and inferences based on bond structures and electron distributions, we propose that the effective thickness of a CNT wall for its continuum representation should be related to the graphitic inter-planar spacing of 3.4Å. We also show that shell element representation of a CNT structure in the FE models properly simulated the carbon-carbon covalent bonding and long-range interactions in terms of the load-displacement behaviors. Estimation of the effective interfacial elastic properties by ab initio simulations showed that the in-plane interfacial bond strength is negligibly weaker than the normal counterpart due to the nature of the weak secondary bonding at the CNT-Al interface. Therefore, we suggest that a third-phase solid element representation of the CNT-Al interface in nanocomposites is not physically meaningful and that spring or bar element representation of the weak interfacial bonding would be more appropriate as in the cases of polymer matrix counterparts. The possibility of treating the interface as a simply contacted phase boundary is also discussed.
        4,000원
        76.
        2010.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Pyeongan Supergroup can be divided into seven lithostratigraphic units (Moscovian to Early Triassic?) in the Samcheok coalfield and four lithostratigraphic units (Bashkirian to Artinskian) in the Yeongwol coalfield of South Korea. On the basis of fusulinid biostratigrapic data in the Yeongwol coalfield, the boundary between the Carboniferous and Permian strata of the Pyeongan Supergroup has been considered as unconformity since the Kasimovian and Gzhelian strata are missing. Protriticites and Triticites, which are the cosmopolitan index fusulinids indicating the Kasimovian and Gzhelian age, are not found from the uppermost part of the Geumcheon and Pangyo Formations. Recently some fusulinids such as Xenostaffella koreaensis, Hanostaffella magna, and Fusulina danyangensis found from the uppermost part of the Geumcheon and Pangyo Formations are recognized as the early Kasimovian-type fusulinids, although the upper Kasimovian- to Gzhelian-type fusulinids are still missing.
        4,200원
        77.
        2010.09 구독 인증기관 무료, 개인회원 유료
        This study deals with the design of a bi-directional liquid damper for a SDOF structure. Two dampers are usually needed to reduce wind-induced responses of tall structures since they are along and across wind ones. The proposed damper has the advantage of controlling both responses with a single damper. The damper shows dynamic behavior of both tuned liquid column damper (TLCD) and tuned sloshing damper (TSD) in the direction of two axes perpendicular with each other. This paper presents experimental verification to confirm its control performance. First, shaking table test is carried out to investigate reducing responses of a SDOF structure by the damper. Control performance of the damper is expressed by the transfer function from shaking table accelerations to SDOF structure ones. Testing results show that the damper reduced bi-directional responses of a SDOF structure. Also, it reduced torsion responses. It was confirmed from system identification results that damping ratio of a SDOF structure increased by the bi-directional liquid damper.
        4,000원
        79.
        2010.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Sperm chromatin integrity is essential for successful fertilization and development of an embryo. Reported here is a quantification of DNA fragments which is intimately associated with reproductive potential to provide one of criteria for sperm chromatin integrity. Three sperm populations were considered: CONTROL (no treatment), UV irradiation (48mW/, 1h) and (oxidative stress induced by hydrogen peroxide, 10 mM, 50 mM and 100 mM). DNA fragments in boar sperm were evaluated by using ligation-mediated quantitative real-time polymerase chain reaction (LM-qPCR) assay, which relies on real-time qPCR to provide a measure of blunt 5' phosphorylated double strand breaks in genomic DNA. The results in agarose gel electrophoresis showed no significant DNA fragmentation and no dose-dependent response to . However, the remarkable difference in shape and position was observed in melting curve of LM-qPCR. This result supported that the melting curve analysis of LM-qPCR presented here, could be more sensitive and accurate than previous DNA fragmentation assay method.
        4,000원
        80.
        2010.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Zirconium diboride (ZrB2) and mixed diboride of (Zr0.7Ta0.3)B2 containing 30 vol.% silicon carbide (SiC) composites were prepared by hot-pressing at 1800˚C. XRD analysis identified the high crystalline metal diboride-SiC composites at 1800˚C. The TaB2 addition to ZrB2-SiC showed a slight peak shift to a higher angle of 2-theta of ZrB2, which confirmed the presence of a homogeneous solid solution. Elastic modulus, hardness and fracture toughness were slightly increased by addition of TaB2. A volatility diagram was calculated to understand the oxidation behavior. Oxidation behavior was investigated at 1500˚C under ambient and low oxygen partial pressure (pO2~10-8 Pa). In an ambient environment, the TaB2 addition to the ZrB2-SiC improved the oxidation resistance over entire range of evaluated temperatures by formation of a less porous oxide layer beneath the surface SiO2. Exposure of metal boride-SiC at low pO2 resulted in active oxidation of SiC due to the high vapor pressure of SiO (g), and, as a result, it produced a porous surface layer. The depth variations of the oxidized layer were measured by SEM. In the ZrB2-SiC composite, the thickness of the reaction layer linearly increased as a function of time and showed active oxidation kinetics. The TaB2 addition to the ZrB2-SiC composite showed improved oxidation resistance with slight deviation from the linearity in depth variation.
        4,000원
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