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        검색결과 1,734

        781.
        2015.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to investigate the effects of vibration on Golgi tendon organ(GTO) and Hold-Relax of PNF in muscular activity and gait factors on Delayed Onset Muscle Soreness(DOMS). This study was conducted on 20 subjects. they were divided into two groups; Hold-Relax of PNF(n=10), Vibration on GTO(n=10). Both of the group was performed interventions 1 times a day for 3 days. The data was analyzed by the repeated-ANOVA for comparing before, after 24h and after 48h changes of factors in each group and the Independent t-test for comparing the between groups. The results are as follows. There was statistically significant difference of before, after 24h and after 48h vibration on GTO group and Hold-Relax of PNF group in muscular activity and gait factors on DOMS.(p<0.05). There was no statistically significant difference of between vibration on GTO group, but there was statistically significant difference Hold-Relax of PNF group in EMG, step width, step length, stride length(p>0.05). As a results of this study, Hold-Relax of PNF group are effective in improving muscular activity and gait factors
        4,000원
        782.
        2015.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We report first results from KVN and VERA Array (KaVA) VLBI observations obtained in the frame of our Plasma-physics of Active Galactic Nuclei (PAGaN) project. We observed eight selected AGN at 22 and 43 GHz in single polarization (LCP) between March 2014 and April 2015. Each source was observed for 6 to 8 hours per observing run to maximize the uv coverage. We obtained a total of 15 deep high-resolution images permitting the identification of individual circular Gaussian jet components and three spectral index maps of BL Lac, 3C 111 and 3C 345 from simultaneous dual-frequency observations. The spectral index maps show trends in agreement with general expectations – flat core and steep jets – while the actual value of the spectral index for jets shows indications for a dependence on AGN type. We analyzed the kinematics of jet components of BL Lac and 3C 111, detecting superluminal proper motions with maximum apparent speeds of about 5c. This constrains the lower limits of the intrinsic component velocities to  0.98c and the upper limits of the angle between jet and line of sight to 20◦. In agreement with global jet expansion, jet components show systematically larger diameters d at larger core distances r, following the global relation d  0.2r, albeit within substantial scatter.
        4,500원
        783.
        2015.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Active Galactic Nuclei (AGN) with bright radio jets o er the opportunity to study the structure of and physical conditions in relativistic out ows. For such studies, multi-frequency polarimetric very long baseline interferometric (VLBI) observations are important as they directly probe particle densities, magnetic eld geometries, and several other parameters. We present results from rst-epoch data obtained by the Korean VLBI Network (KVN) within the frame of the Plasma Physics of Active Galactic Nuclei (PAGaN) project. We observed seven radio-bright nearby AGN at frequencies of 22, 43, 86, and 129 GHz in dual polarization mode. Our observations constrain apparent brightness temperatures of jet components and radio cores in our sample to > 108:01 K and > 109:86 K, respectively. Degrees of linear polarization mL are relatively low overall: less than 10%. This indicates suppression of polarization by strong turbulence in the jets. We found an exceptionally high degree of polarization in a jet component of BL Lac at 43 GHz, with mL  40%. Assuming a transverse shock front propagating downstream along the jet, the shock front being almost parallel to the line of sight can explain the high degree of polarization.
        4,600원
        784.
        2015.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present our efforts for extending the simultaneous multi-frequency receiver system of the Korean Very Long Baseline Interferometry (VLBI) Network (KVN) to global baselines in order to measure the frequency-dependent position shifts in Active Galactic Nuclei (AGN) jets, the so called core shift effect, with an unprecedented accuracy (a few micro-arcseconds). Millimeter VLBI observations with simultaneous multi-frequency receiver systems, like those of the KVN, enable us to explore the innermost regions of AGN and high precision astrometry. Such a system is capable of locating the frequency dependent opacity changes accurately. We have conducted the feasibility test-observations with the interested partners by implementing the KVN-compatible systems. Here we describe the science case for measuring the core shift effect in the AGN jet and report progress and future plans on extending the simultaneous multi-frequency system to global baselines.
        4,000원