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- 저자 : 오철한 (검색결과 65 건)
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오철한 慶北大學校 師範大學 1988 敎育硏究誌 Vol.30 No.-
Blue-Green lasers have the most potential use in underwater development. A survey has been made to review the present state of the blue-green laser technology and future plans for achieving the deisred goals.
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Ar 放電管에 있어서 Primary 및 Secondary Light Pulse의 特性
吳喆漢,李成萬 慶北大學校 師範大學 1985 敎育硏究誌 Vol.27 No.-
Characteristics of primary and secondary light pulses in Ar discharge tube which is being used as a pumping source for a dye laser have been studied by using two different light detectors, photodiode (visible light sensitive) and photomultiplier (uv sensitive). Two narraw and parallel slits are also empolyed for time analysis of light pulses from a small section of the discharge tube. The primary light pulse has a short pulse width and near uv wavelength, and the secondary light pulse has a longer pulse width and visible light wave. Therefore, the primary pulse is suitable for pumping a uv pulse laser and the secondary pulse is suitable for a visible dye laser pumping.
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색소혼합법과 분리법에 의한 색소레이저의 에너지증가 비교
吳喆漢,徐旭昶 慶北大學校 1989 論文集 Vol.47 No.-
In order to increase the laser energy, the mixed dye method and the separated dye method were employed in a blue-green dye laser system. The laser dye and converter dye were LD490 and BBQ respectively. The solvent was pure methanol in which both dyes were solvable. With the mixed dye method, energy increase of 193% was obtained, where the optimum BBQ concentration was 4.6×10 exp (-6)M. With the separated dye method, the maximum energy increase was 90% where the BBQ concentration was 1.0×10 exp (-5)M.
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吳喆漢,尹文洙,李峻石 慶北大學校 産業開發硏究所 1979 硏究報告 Vol.7 No.-
The characteristics of the corona onset of point-to-plane gap under negative steady potentials in air were studied by using a quartz-lens camera, an electrometer, a Van de Graaff generator and an osilloscope. The results indicated that the larger the point radius was, the more irregular corona observed. As the gap length increases, the corona onset potential increased exponentially in the short range and increased linearly for the constant point radius and as a funtion of point radius for the fixed gap length. The corona current decreased as the gap length increased for the constant point radius while it increased as the point radius increased with the fixed gap length. As to the corona figure, we have also found that the axial length of streamers increased slowly for the increase of gap length.
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不均等 電氣場에 있어서 正極性 直流 CORONA의 發生 特性
吳喆漢,尹文洙 慶北大學校 産業開發硏究所 1977 硏究報告 Vol.5 No.-
The characteristics of corona onset of point-to-plane gap under positive steady potentials in air were studied by means of a quartz-lens camera and an oscilloscope. A Van de Graaff generator which could produce a potential of 350 kV as maximum was used for the high potential source and various point electrodes whose tip radii ranging from 0.5㎜ to 5㎜ were used as anode. The results show that the frequency of corona was decreased as the gap length was increased and the frequency of corona was increased as the radius of anode tip was increased. As to the corona figure, it was known that the axial length of streamers were proportional to the radius of anode tip, and the distance to the maximum radial spreading point of streamers along the gap axis became smaller to the anode tip as the radius of anode tip was decreased.
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吳喆漢 경북대학교 교육대학원 1977 논문집 Vol.9 No.-
The process of the electrical breakdown of a relatively short air gap forming a nonuniform field was observed by still pictures which were taken by means of the potential chopping method. The results show that the primary streamers easily progress to the cathode, but the secondary streamers fail to reach the cathode even under flash-over potentials; that the leader is present even in a short gap and it proceeds by way of a primary-secondary-leader stem step; and that as soon as the leader arrives at the cathode, its channel changes into a spark channel.
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Lichtenberg Figure法에 의한 電氣絶綠材料의 開發
吳喆漢,尹文洙,李峻石 慶北大學校 1980 論文集 Vol.29 No.-
The characteristics of Lichtenberg Figures on X-ray films and electrical insulators, and their breakdown processes under positive impulse potentials were investigated using two photomultipliers and an oscilloscope. The results are follows; (1) It was found that two kinds of streamers are appeared in coplaner mode, that is air streamers and film streamers. The former travels with a speed of about 10°cm/sec while the later about 10^7cm/sec. (2) The length of film streamer is not proportional to the applied voltage but to the streamer onset voltage. The current of Lichtenberg Figure on X-ray is increased as an exponential function of the onset voltage. (3) The spark breakdown process of Lichtenberg Figure on X-ray film is similar to that of air, regarding the voltage, current and light pulse oscillograms when the spark is occurred. The spark follows a leader channel which is formed by steps after the primary type streamers were appeared several times. (4) On the surface of solid insluators, the streamer onset voltage is increased as the surface resistivity of insulator is increased. The length of Lichtenberg Figure is proportional to the relative permittivity of insulator and is inverse proportional to the thickness of insulator.
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吳喆漢 慶北大學校 1977 論文集 Vol.23 No.-
The temperatures of the plasma in spark and leader channels of a short gap at the atmospheric pressure have been measured by the emission spectrochemical analysis. The spark plasma shows a temperature range of 3000∼8000°K which means that its channel is not in an arc state.
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色素레이저에 있어서 HCP의 不均一 放電이 미치는 影響
吳喆漢 慶北大學校 1984 論文集 Vol.37 No.-
The shadow effect and nonuniform discharge effect of HCP on dye laser pumping have been investigated with HCP model. The shadow effect of separators which are employed as disk electrodes of HCP shows about 18∼20% decreasing result of pumping light intensity. However, the nonuniform distribution effect of puming light is more important problem for dye laser pumping. Therefore, it must be emphasized that electrodes of HCP should be imporved so that uniform discharge and uniform distribution of pumping light of them could be produced.
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空氣中 Primary 및 Secondary Streamer의 特性
吳喆漢 慶北大學校 1972 論文集 Vol.16 No.-
By means of the Lichtenberg figure technique, further study of the streamer dendrites formed in a positive rod-to-plane gap at, or very near the spark breakdown voltage has been made. In these studies, carried out in room air, the photographic films were placed at various planes normal to the axis of the gap system. The results led to identification of the previous observations by photomultiplier-fast CRO technigue. The secondary streamers were able to distingushed from the primaries even in these Lichtenberg figures. Streamer branchings (axial and radial) and streamer tip potentials were investigated and discussed for the understanding of streamer mechanism.
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