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시간 스케일러빌리티를 이용한 MPEG-4 FGS 비디오 부호화 기법
김종욱,이배호 전남대학교 전자통신기술연구소 2002 전자통신기술논문지 Vol.5 No.1
The paper shows MPEG-4 FGS(Fine Granularity Scalability) using the scalable video encoding technique that is adapted by MPEG-4 standard and a scheme to improve its efficiency. MPEG-4 FGS is the encoding technique that has the good flexibility for various property of devices and bandwidth variation over the internet. To improve MPEG-4 FGS coding efficiency, we applied an encoding technique with temporal scalability. In other words, the base layer is encoded with the same technique as the typical MPEG-4 FGS and the enhancement layer is encoded by adding temporal scalability property In test results, we could know that had better coding efficiency in the case of adding temporal scalability for the enhancement layer.
Nerve Growth Factor로 분화된 PC12 세포에서 GABA 및 NMDA 수용체의 전기생리학적 특성
김종욱,송대규,배재훈,박원균 啓明大學校 醫科大學 2002 계명의대학술지 Vol.21 No.1
NGF로 분화시킨 PC12 세포에서 NMDA 수용체 및 GABA 수용체의 전기생리학적 특성을 관찰하고자 배양 7∼14일 사이의 PC12 세포를 이용하여 whole-cell patch clamp 방법으로 안정막전압 및 막전압의 변동에 따른 이들 수용체 전류의 특성을 기록하였다. 관류액에 20 μM APV를 투여한 후 안정막전압은 유의한 변동이 없었다. 막전압을 -80 mV에서 -10 mV까지 단계적으로 고정하였을 때 발생하는 NMDA 수용체 전류는 막전압이 과분극될 때는 내향성, 탈분극될 때는 외향성의 전류가 측정되며 그 크기는 과분극에 비하여 탈분극 시 유발전류의 증가폭이 점점 더 크게 나타나는 막전압에 의존적이었다. 활동전압 및 glutamate 수용체를 차단한 후 20 μM GABA를 투여한 후 안정막전압이 약간 과분극되는 세포에서 막전압을 -80 mV에서 -10 mV까지 단계적으로 고정하였을 때 발생하는 GABA 수용체 유발전류는 막전압이 과분극될 때는 외향성, 탈분극될 때는 내향성의 전류가 측정되며 30 mV까지는 막전압의 변동과 유발전류사이에 직선적인 관계가 관찰되었다. 이상으로 NGF로 분화시킨 PC12 세포주에서 NMDA 수용체 및 GABA 수용체의 전기생리학적 특성은 생체의 신경계에서 발견되는 수용체 특성과 유사한 것으로 생각되며, PC12세포는 이들 수용체에 대한 다양한 전기생리학적 실험의 연구재료로 충분히 이용될 수 있을 것으로 생각된다. Nerve growth factor (NGF), which has been used for the differentiation of PC12 cells in culture, not only promotes the survival and differentiation of neurons but also affects the suructural and functional properties. The aim of this study was to investigate the current properties of NMDA and GABA receptors by using whole-cell patch clamp technique in NGF differentiated PC12 cells cultured for 7∼14 days. Membrane potential did not change from the resting potential of -48 mV by the infusion of a NMDA receptor blocker, APV, (50 μM) in the perfusion solution. NMDA components of the evoked currents at the membrane potential, changing from -80 mV to -10 mV. showed a voltage dependency in the current-potential relationship. When action potential and glutamate receptors were blocked, membrane potential was hyperpolarized by the infusion of GABA (20 μM) in some PC12 cells, but not in other cells. In the hyperpolarized cells, GABA components of the evoked currents at the membrane potential, changing from -80 mV to -10 mV, showed a linear correlation between the currents and the membrnae potential. In conclusion, the electrophysiological properties of NMDA and GABA receptors in NGF differentiated PC12 cells may be similar to those in the biological neurons. Therefore, it seems that PC12 cells appear to be suited for the studies on function and signal transmission of these receptors.
김종욱,M . S . 아흐마드 . W . D . 킷츠 ( J . W . Kim,M . S . Ahmadd,W . D . Kitts ) 한국축산학회 1978 한국축산학회지 Vol.20 No.1
The subcellular structure of epididymal spermatozoa obtained from standard dark mink was studied by means of electron microscopy, using thin-sectioning techniques. The spermatozoan head was seen to be dorsoventrally flattened and ovate in outline. The anterior two-third of the nucleus was covered with the acrosome which can be divided into three segments (apical, man and equatorial) according to the acrosomal content. The posterior one-third was covered with the postaucrosomal sheath which was a dense layer deposited on the inner aspect of the cell membrane. On the dorsal and ventral and ventral and ventral aspects of the bead, six swellings were observed; two of these were located at each side of the proximal border of the equatorial segment, and one was associated with the pestacrosomal region on each side. The cell membrane adhered firmly to the tip of the acrosome and to the postacrosomal sheath, but was found to be usually separated from the rest of the acroseme. The articular structure of the neck appeared to show separate dorsal and ventral plates of the capitulum which were followed by a ring of striated columns of the connecting piece. These striated columns were followed by two major and five minor columns which appeared io continue with the nine dense fibers of the axial fiber bundles. Beneath the inner surface of the capitulum, the proximal centriole wes found in the center of the connected ring. The spermatozoan tail displayed a 9+9+2 pattern in the organization of the axial fiber bundle consting of the dense fibers, double microtubules, and a central pair. The dense fibers number 9, 1, 5, and 6 were larger in diameter than the rest of the dense fibers. In the axonemal complex, the diameter of subfiber A was larger than the central fiber, while that of subfiber B was the smallest. The middle piece was of medium length compared with other mammalian spermatozoa. The annulus was triangular in longitudinal sections and contained nonhomogeneously distributed electron dense material. The fibrous sheath had longitudinal columns. Although the end piece maintained the 9+2 pattern, it did not have the fibrous sheath.
김종욱,M . S . 아마드 . W . D . 킷츠 . C . R . 크리쉬나머터 ( J . W . Kim,M . S . Ahmad,W . D . Kitts,C . R . Krishnamurti ) 한국축산학회 1977 한국축산학회지 Vol.19 No.4
Epididymal spermatzea of mink were used to study the ceallurar localization of several enzymes. Very strong acid phosphatase activity was found in the equatorial region of the head and tail(middle and principal pieces) of spermatozoa while strong activity was found in the galea dapitis, acrosome, and postacrosomal sheath. Strong alkaline phosphatnse activity was detected in the galea capitis acrosome, post-acrosomal sheath and tail. The activity of glucose-o-phosphatase and 5-nucleotidase were confined to the middle piece. The reaction of glucoseo-phosphatase was very strong while that of 5-nucleotidase appeared weak. The activity of ADPase and ATPase was distributed strongly in the tail and it was localized weakly in the acrosome and postacrosomal sheath. The galea capitis was weakly stained by ATPase. Most phosphatases were localizd in the acrosome postacrosomal sheath, and tail, with the exception of glucose-6-phosphatatase and 5-nucleotidase which were confined to the middle piece. Weak non-specific esterase activity was located in the base of the head and middle piece. The activity of DOPA oxidase was weakly spread in the acrosome, postacrosomal sheatin, and tail. Although the activity of malate dehydrogenase was distribueted in the base of the head and tail, the rest of the dehydrogerase activity examined (succinate, lactate, and isocitrate dehydrogenases except 6-phosphogl accnic dehydrogenase) was confined to the middle piece. The activity of succinate was the strongest among the examined dehydrogenases. The activity of NADH diaphorase was strongly confined to the middle piece. The metabolic enzymes (glueose-6 phosphatase, dehidrogeanses, and NADH diaphorase) were confined to the middle piece, while the activity of malate clehydrogenase was found so be extended to the head base and base and principal piece. The lytic enzymes, acid phosphatase and esterase were localized in the acrosomal portion.