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        검색결과 343

        101.
        2008.05 구독 인증기관·개인회원 무료
        The multicolored Asian ladybird beetle, Harmonia axyridis, which demonstrates typical genetic polymorphism in its elytra color patterns. Early studies have color polymorphism in terms of geographical clines while a few investigated temporal populations in Coccinellidae. Nevertheless, note that geographical and temporal morph variation does not always correspond to what is expected from thermal and industrial adaption theories. A recent study of transformation and RNAi of the ladybird beetle, however, there is yet no evidence to indicate the variation is genetic or environmental factors. Here we describe a relatively new molecular fingerprinting technique, amplified fragment length polymorphism (AFLP). Because we think that color polymorphism in Coccinellidae is affected by genetic polymorphism. In total 38 markers were scored from which some markers were polymorphic. Supsequent UPGMA cluster analysis revealed 3 major group of Harmonia axyridis populations. But for strains that are more genetically similar, different primer combinations may be need to generate enough polymorphic marker.
        102.
        2008.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 철근콘크리트 특수모멘트골조(SMF)내 보-기둥 접합부의 비탄성 회전능력에 대한 연구결과를 조사한 것이다. 모든 실험체들은 ACI 318-02에 정의된 설계 및 세부지침에 따라 특수모멘트골조로 분류되었다. AISC(2002)기준에서 모멘트골조의 접합부에 대한 내진성능의 만족 기준을 이용하여 보-기둥 접합부를 평가하였다. 총 39개의 실험체들에 대해 자세하게 조사되었다. 특수모멘트골조에 대한 내진설계기준을 만족하는 대부분의 접합부들은 3%의 소성회전까지 휨강도의 심각한 감소 없이 연성이 유지되었다. 이는 특수모멘트골조 접합부들에 대한 엄격한 콘크리트 내진설계 규정에 따른 것으로 조사되었다. 접합부내의 횡방향 보의 존재는 보-기둥 접합부의 구속력과 전단에 대한 저항성을 증가시킨 것으로 조사되었다 접합부 전단응력에 대한 ACI 328-02 제한조건을 만족하는 모든 특수모멘트골조의 접합부들은 요구되는 내진성능을 만족하는 것으로 나타났다.
        4,000원
        103.
        2008.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        A 532 nm Nd-YAG laser was applied to crystallize amorphous Si thin films in order to evaluate the applicability of a Nd-YAG laser to low-temperature polycrystalline Si technology. The irradiation of a green laser was controlled during the crystallization of amorphous Si thin films deposited onto glass substrates in a sophisticated process. Raman spectroscopy and UV-Visible spectrophotometry were employed to quantify the degree of crystallization in the Si thin films in terms of its optical transmission and vibrational characteristics. The effectiveness of the Nd-YAG laser is suggested as a feasible alternative that is capable of crystallizing the amorphous Si thin films.
        3,000원
        104.
        2008.03 구독 인증기관 무료, 개인회원 유료
        In this study, based on the results from the sinusoidal base excitation analyses of a single degree of freedom system with a tuned mass damper (TMD) , the optimal friction is computed so that the rail friction improve the performance of the TMD. The magnitude of the optimal friction increases with increasing mass ratio of the TMD and decreases with increasing structural damping. Particularly, it is observed that the optimized friction force gives better control performance than the optimized viscous damping of the TMD. However, because the performance of the TMD considerably deteriorates when the friction force increases over the optimal value, it is required to keep the friction force from exceeding the optimal value. Based on the results from this study, it is possible to economically design the TMD by avoiding the unconditional minimization of the rail friction and in some cases by removing the additional damping devices of which function can be performed by the rail friction.
        4,000원
        105.
        2008.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구의 목적은 학생들이 과학 이론과 과학 법칙의 차이를 어떻게 이해하고 있는가를 알아보는 것이다. 과학 지식의 서로 다른 종류인 과학 이론과 과학 법칙에 대해서 올바르게 이해하고 있는 것은 과학의 본성을 이해하는 데 있어서 매우 중요함에도 불구하고 이에 대한 연구는 충분히 이루어지지 않고 있기 때문이다. 본 연구에서는 서울 지역의 고등학교 학생 32명을 대상으로 개방형 질문으로 구성된 설문을 실시하였다. 조사 결과, 학생들은 '과학 이론은 아직 증명되지 않은 것이며, 과학 법칙은 확실히 증명된 것이다.' 및 '과학 이론이 충분한 증거가 뒷받침되어 증명되면 법칙이 된다.'는 오개념을 가지고 있는 것으로 나타났다. 아울러 학생들이 알고 있는 과학 이론의 상당수가 지구과학 과목에 포함되고, 알고 있는 과학 법칙의 대부분이 물리, 화학 과목에 포함되어 있는 것으로 미루어, 지구과학을 덜 과학적인 학문으로 잘못 인식하고 있을 가능성도 보였다. 따라서 과학 이론과 과학 법칙에 대한 분명한 차이를 이해하는 것은 지구과학에 대한 올바른 인식에도 도움을 줄 것으로 기대된다.
        4,000원
        106.
        2008.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this study, calcium titanate (CaTiO3) gel was prepared by mixing calcium nitrate and titanium isopropoxide in 2-methoxy-ethanol. CaTiO3 gel was single-layer coated on Ti-6Al-4V using a sol-gel dip-coating technique. The coating was calcined at 750˚C in air by utilizing a very slow heating rate of 2˚C/min. The crystalline phases of the coating were characterized by x-ray diffraction using a slow scan rate of 1˚/min. The morphology of the coating was analyzed by scanning electron microscopy. The corrosion behavior of Ti-6Al-4V samples coated with CaTiO3 films were tested in an artificial saliva solution by potentiodynamic polarization and were quantified by the Tafel extrapolation method. The electrochemical parameters showed a considerable increase in the corrosion resistance for the CaTiO3-coated Ti-6Al-4V samples compared to bare substrates.
        3,000원
        107.
        2007.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was carried out to investigate the effect of morphology of oocytes, kinds of media, cysteine and myo-inositol supplementation on IVM rate of porcine oocytes. Cumulus- enclosed oocytes were incubated in maturation NCSU-23 and TCM-199 medium with supplementation with 3, 5, 10, 20 mM myo-inositol and 0.05, 0.1, 0.5, 1.0 mM cysteine. 1. When classified by morphology, excellent, good and fair of cumulus-enclosed oocytes were incubated for 48 hrs and the IVM rate were , respectively. The rate were greater in oocytes with excellent cumulus cells than those without cumulus cells. 2. The IVM rate of oocytes cultured in TCM-199 and NCSU- 23 medium supplementation or non-supplementation with 1.0 mM myo-inositol were , respectively. Supplementation with myo-inositol significantly increased the IVM rate of oocytes. 3. The IVM rate of oocytes cultured in NCSU-23 medium supplementation of 3, 5, 10, 20 mM myo-inositol for 48 hrs were , respectively. The IVM rate of oocytes in NCSU-23 medium supplemented with 10 mM myo-inositol were significantly increased compared to control (). 4. The IVM rate of oocytes cultured for 48 hrs in NCSU-23 media supplement with 0.3, 0.5, 1.0, 2.0 mM myo-inositol were , respectively. The IVM rate of oocytes in NCSU-23 medium supplemented with 10 mM cysteine were significantly increased compared to control ().
        4,000원
        108.
        2007.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        These study was carried out to investigate the effects of the collection time, culture time and activation of canine oocytes on in vitro maturation rates. The activated oocytes were cultured in 10% FCS+TCM-199 media containing hormonal supplements (10 IU/ml HCG, 10 IU/ml PMSG, 10 ug/ml gonadotropin) at 5% , 95% air, . 1. IVM rate of in vitro cultured cumulus-attached oocytes recovered from ovaries that collected at follicular and luteal stages of the reproductive cycles were 11.4% and 5.7%, respectively. IVM rate of oocytes recovered from ovaries that collected at follicular stages of the reproductive cycles was significantly higher than that of luteal stage (p<0.05). 2. When IVM was carried out at different periods of 40, 48, and 70 hrs, the IVM rates of oocytes matured in vitro were 2.9%, 8.6%, 5.7%, respectively. These results indicate that the IVM time between hrs gives the highest maturation rate for the oocytes matured at the different stages. 3. IVM rate of oocytes matured in vitro for 10 hrs after single and combined activation treatment by ET, IP and CH and Ca+DMAP, CH+DMAP, ET+CH were respectively. This was higher than that in both single and combined stimulated groups compared to control group ().
        3,000원
        109.
        2007.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        제주도는 현무암과 조면암으로부터 기원한 투수성 높은 토양으로 인하여 지표수 유입에 따른 상시하천 발달이 어려워, 용수의 대부분을 지하수에 의존하고 있다. 이에 따른 무분별한 지하수 개발은 지하수위 강하로 이어져, 제주도내 많은 지역에서 지하수 오염과 해수침투 현상이 나타나고 있다. 제주특별자치도는 제주도의 항구적인 지하수자원 보전을 위하여 1994년 이래 일부 지역을 지하수 보전구역으로 지정하였으며, 이 지역내의 모든 지하수 개발은 허가를 받도록 지정한 바 있다. 또한 지하수 수문과 관련된 수리지질 정보 획득을 위하여, 2001년 이래로 제주도 내 해안지역 및 저지대 전체를 대상으로 지하수 관측망을 설치 운영 중이다. 본 연구에서 이러한 지하수 관측망으로부터 얻어진 지하수위, 수온, 전기전도도 등 장기 관측자료를 분석한 결과, 북부 해안지역의 경우 지하수위가 지속적으로 하강하는 것으로 나타났다. 또한 동부 해안지역의 경우는 최근 취수량의 급격한 증가에 따른 해수침투의 영향으로, 대부분의 관측정에서 전기전도도가 높게 나타나며 지속적으로 증가하고 있는 추세로 분석되었다. 이러한 문제점들은 지하수 개발과 관련하여 제주특별자치도의 강력한 통제로 인하여 최근들어 감소하는 추세이지만, 본 연구 결과에 의하면 해안지역의 경우에는 지하수위 하강 및 전기전도도 상승 현상이 지속될 것으로 판단된다.
        4,200원
        112.
        2007.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Using data from 132 telephone interviewees, we examined the role of affective-cognitive ambivalence in forming overall attitude and behavior toward toxic chemical and radioactive waste issues in Marion, Ohio in the U.S. In order to compare attitudinal preference, participants were divided into four A-C groups: action-group (Affective+/Cognitive+), detached-group (A-/C+), concerned-group (A+/C-), and inaction-group (A-/C-). Affective and cognitive components interacted, producing redundant influences on overall attitudes and judgments as frequently observed and postulated in previous attitude studies. The results showed that the action-group who were feeling unsafe and believed that environmental accidents had happened or are happening in Marion were less willing to move to the area than other three groups who were feeling safe and/or doubted reports of contamination and its relation with leukemia. Affective and cognitive components were found to have redundant influences on overall attitude. It was also observed that affective-cognitive ambivalence theory has a great potential for explaining the mechanism by which people form attitudes, especially when people have moderate or positive feelings (e.g. sympathy or eagerness for resources) toward the objects and/or when uncertainty is a major feature of environmental issue under consideration (e.g. global climate change).
        4,000원
        113.
        2007.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A long-term in situ observation was carried out in the Ice-valley at Milyang in order to explain the factors and processes associated with the summertime ice formation. The variation of temperature inside Ice-valley in relation with ice formation in summer time was found to depend on precipitation rate in spring and cold air sinking in autumn and winter. The rate of temperature rising tends to correspond to sensible heat release depending on the precipitation amount at the freezing location. The reason of the cold air accumulation in a talus in the Ice-valley is the cold air sinking over the surface of talus due to the occurrence of outside clod air mass and the accumulated cold air from autumn to spring flow outside at the bottom of talus. The out-flowing cold air can result in the ice formation in the hot summer.
        4,000원
        114.
        2007.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The interdecadal variation of wintertime blocking frequency over the Siberia (60˚E-140˚E) is examined using the ECMWF/NCEP-NCAR re-analysis data for the period 1958-2006. The wintertime blocking frequency over the Siberia significantly decreased for the period 1986-2006, compared to the period 1958-1985, which is mainly due to the anomalous circulation of 500-hPa geopotential height field. During the period 1986-2006, there was enhancement in both the anomalous cyclonic flow over the western Siberia and the anomalous anticyclonic flow over the east Asia. These anomalous circulation patterns, which might be associated with changes in surface temperatures over the Asian continent, are suspected to playa possibly important role as an obstacle to the formation of blocking flow over the Siberia.
        4,000원
        115.
        2007.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Seismic design codes are developed mainly based on the observation of the behavior of structures in the high seismicity regions where structures may experience significant amount of inelastic deformations and major earthquakes may result in structural damages in a vast area. Therefore, seismic loads are reduced in current design codes for building structures using response modification factors which depend on the ductility capacity and overstrength of a structural system. However, structures in low seismicity regions, subjected to a minor earthquake, will behave almost elastically because of the larger overstrength of structures in low seismicity regions such as Korea. Structures in low seismicity regions may have longer periods since they are designed to smaller seismic loads and main target of design will be minor or moderate earthquakes occurring nearby. Ground accelerations recorded at stations near the epicenter may have somewhat different response spectra from those of distant station records. Therefore, it is necessary to verify if the seismic design methods based on high seismicity would he applicable to low seismicity regions. In this study, the adequacy of design spectra, period estimation and response modification factors are discussed for the seismic design in low seismicity regions. The response modification factors are verified based on the ductility and overstrength of building structures estimated from the farce-displacement relationship. For the same response modification factor, the ductility demand in low seismicity regions may be smaller than that of high seismicity regions because the overstrength of structures may be larger in low seismicity regions. The ductility demands in example structures designed to UBC97 for high, moderate and low seismicity regions were compared. Demands of plastic rotation in connections were much lower in low seismicity regions compared to those of high seismicity regions when the structures are designed with the same response modification factor. Therefore, in low seismicity regions, it would be not required to use connection details with large ductility capacity even for structures designed with a large response modification factor.
        4,200원
        116.
        2007.04 KCI 등재 구독 인증기관·개인회원 무료
        Sulfur is commonly used in Asia as an herbal medicine to treat inflammation and cancer , a nd potent chemo preventi ve effects have been demons tra ted in various in vivo and in vitromodels for s ul fur-containing compounds found in natura l1y occurring product s. Here, we 1'eport the growth inhibitory and apoptosis-related effects of a n ewly developedhigh-puri ty edible sulfur(ES) on immo1'tali zed human o1'al ke1'atinocytes(IHOKs) and on oral cancer cells representing two stages of oral cancer (HN4‘ HN12) based on an 3-(4,5-Dimethylthiazol-2-yl) -2.5- diphe n yltetrazolium bromide(MTI) assay, Western blotting, cell cycle analysis, and nuclear staining. The puri ty of the ES used in thi s study was ve1'ified by high performance liquid chromatog1'aphy (HPLC) , ami no acid analysis and energy dispersive spectroscopy(EDS). ES inhibited the prolife1'ation of imrnortalized and ma lig nant o1'al kerati nocytes in a dose- and time-dependent manne1' FITC-Annex.in V staining, DNA fragmentation t esting. and Hoechst 33258 s taining revealed that ES inhibits cell growth via apoptosis. ES bl ocked cell-cycle prog1'ession at t he sub-Gl phase‘ wi th decreased expression of cyclins Dl, D2‘ and E, and their activating partn ers cdk2‘ cdk4‘ and cdkfì, and a concomitant induction of p53 and p21/WAF1. Furthe1'more, ES treatment in creased the cytosolic level of cytochrome c and resulted in caspase- 3 activation‘ and thi s effect was co1'1'elated with Bax up-regulation and Bcl-2 down-1'egulation Taken together‘ these data suggest that ES is a potential chemopreventive and chemotherapeut ic agent fo r oral ca ncer
        117.
        2007.03 구독 인증기관 무료, 개인회원 유료
        Forced vibration testing is important for correlating the mathematical model of a structure with the realone and for evaluating the performance of the real structure. There exist various techniques available for evaluating the seismic performance using dynamic and static measurements. In this paper, full scale forced vibration tests simulating earthquake response are implemented by using a hybrid mass damper. The finite element(FE) model of the structure was analytically constructed using ANSYS and the model was updated using the results experimentally measured by the forced vibration test. System identification of real-scaled 5 story building structure which is located in UNISON INC. is conducted on the updated FE model.
        4,000원
        120.
        2006.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The goal of this study is to elucidate the fusulinid biostratigraphy of the Carboniferous limestones distributed in the Gangdong area of Samcheok coalfield, Korea. The Carboniferous strata of the study area mainly comprise alternaton of dark gray shale, dark gray and reddish sandstone, and gray limestone. The limestones consist mainly of wackestonepackstone containing various fossil fragments such as crinoid, coral, brachiopod, foraminifera, fusulinid, and bryozoa; this observation thus suggests that the study site was the shallow marine environments. A tital of 12 species belonging to 5 genera of fusulinids are identified from the limestones of the Gangdong geologic section: Ozawainella turgida Sheng, Ozawainella sp. A, Ozawainella magna Sheng, Pseudostaffella antiqua (Dutkevich), Pseudostaffella paracompressa Safonova, Pseudostaffella kimi Cheong, Pseudostaffella sp., Beedeina lanceolata (Lee and Chen), Beedeina samarica (Rauser-Chernoussova), Beedeina sp. A, Neostaffella sphaeroidea cuboides Rauser-Chernoussova, and Hanostaffella hanensis Cheong. Such fusulinids species were reported from the lower part of the Geumcheon Formation in Samcheok coalfield and the middle Moscovian stage in Eurasia. On the basis of the fusulinid biostratigraphic correlation of the Gangdong geologic sections (A) to (C), the limestone should be overlapped by faults and folds. Moreover the stratigraphic thickness of the limestone is thinner than the thickness of the limestone outcrop of the Gangdong geologic section. Therefore, the stratigraphic sequence of the Gangdong geologic section is represented as the Gangdong geologic section (A).
        4,000원