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허광삼,문성익,김흥수,양두영 濟州大學校 産業技術硏究所 2001 산업기술연구소논문집 Vol.12 No.1
This paper deals with designing the mobile station power amplifier of IMT-2000 using analog predistortion method. The power amplifier made up of 3-stage class-AB amplifiers in cascade. By choosing the final stage as the balanced structure. the output linearity is enhanced. The balanced structure of amplifier is composed of the Wilkinson power divider and combiner. Therefore. to compensate for the linearity of the power amplifier. pre-distorter circuit is inserted in front of 3-stage amplifier. The pre-distorter is implemented using parallel Schotty diode. The optimized linear power amplifier is cornposed of these pre-distorter and 3-stage power amplifier.
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허광삼,문성익,김홍수,양두영 제주대학교 산업기술연구소 2001 尖端技術硏究所論文集 Vol.12 No.1
This paper deals with designing the mobile station power amplifier of IMT-2000 using analog predistortion method. The power amplifler made up of 3-stage class-AB amplifiers in cascade. By choosing the final stage as the balanced structure, the output linearity is enhanced. The balanced structure of amplifier is composed of the Wilkinson power divider and combiner. Therefore, to compensate for the linearity of the power amplifier, pre-distorter circuit is inserted in front of 3-stage amplifier. The pre-distorter is implemented using parallel Schotty diode. The optimized linear power amplifier is composed of these pre-distorter and 3-stage power amplifier.
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철근콘크리트 기둥의 좌굴파괴에 의한 철근비 및 큰크리트 압축강도의 실험적 연구
김광석,장정수,박진희 조선대학교 국토개발연구소 1997 국토개발연구 Vol.17 No.1
This study investigates the effect of compressive strength and longitudinal steel ratio of concrete on the behavior of reinforced concrete columns and conducts the experiment of the behavior of reinforced concrete columns with normal and high strength by giving a slenderness ratio(λ=50) the columns with square section (100×100 mm) to analyze the relations to bending moment, bending displacement and ultimate strength and by having the variables of concrete compression strength (180kgf/㎠, 819kgf/㎠) and longitudinal steel ratio (0.5%, 1%, 4%, 5.7%, 10.3%). As a result, the strain of compressed steel shows considerably increased trend more than tensile steel strain and on the form of fracture in the case of low strength, as the longitudinal steel ratio is increased more, the number of crack in considerably increased and on the form of fracture in the case of high strength, there in little crack in early loading, but when it reaches the ultimate loading, it causes instantaneous breaking. Especially, when column of 0.5% and 1% of longitudinal steel ratio reaches its ultimate loading, it is broken with the phenomena that the both sides of central part are divided, and the cases of 5.7% and 10.3% of longitudinal steel ratio, the ultimate loading value is not greatly increased.
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김범철,박주현,허우명,임병진,황길순,최광순,최종수 江原大學校 附設 環境硏究所 2001 環境硏究 Vol.18 No.-
In this study limnological characteristics of Lake Juam was surveyed from June 1993 to May 1994 in order to provides important information regarding water resources. Seschi disc transparency, epilimnetic chlorophyll a(chl-a), tatal nitrogen(TN), total phosphorus(TP) concentration and primary productivity were in the range of 2.0~4.5 m, 0.9~13.6 mgChl/㎥, 0.78~2.32N/l, 11~56 mgP/㎥, 270~2,160mgCm^(-2)day^(-1), respectively. On the basis of TP, Chl-a and Secchi disc depth, the trophic state of Lake Juam can be classified as mesotrophic lake. The phosphorus inputs from non-point sources are concentrated in heavy rain episodes during the monsoon season. As a result, phosphorus concentration are higher in summer than in winter. TP loading from the watershed were estimated to be 0.9 gPm^(-2)yr(-1), which correspond to a boundary of the critical loading (1.0 gPm^(-2)yr(-1), which correspond to a boundary of the critical loading (1.0 gPm^(-2)yr(-1)) for eutrophication. From the results of the algal assay, both phosphous and nitrogen act as limiting nutrients in algal growth. The seasonal succession of phytoplankton community structure in Lake Juam was similar to that observed in other temperate lakes. Diatoms(Asterionella formosa and Aulacoseira granulata var. angustissima) were dominant in spring and winter, cyanobacteria (Microcystis aeruginosa, M. sp. and M. viridis) were dominant in warm season. The organic carbon, nitrogen and phosphorus content of lake sediment were 9.5~14.0 mgC/g, 1.01~1.82 mgN/g, and 0.51~0.65 mgP/g, respectively. The allochthonous organic carbon loading from the watershed and autochthonous organic carbon loading by primary production of phytoplankton were determined to be 1,122 tC/yr and 6,718 tC/yr, respectively. To prevent eutrophication of Lake Juam, nutrient management of watershed should be focus on reduction of fertilizer application, proper treatment of manure, and conservation of topsoil as well as point source.
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김창원,고주형,최광수,허남효,김병군 釜山大學校生産技術硏究所 1999 生産技術硏究所論文集 Vol.56 No.-
하수처리장 운전 제어 및 자동화는 현재 세계적인 추세이다. 자동 제어를 도입함으로써 운전의 효율성 및 안정성 향상, 일관된 운전, 운전비용 절감 등 많은 이득을 기대할 수 있다. 유럽 등 선진국에서는 이미 7,80년대부터 다방면에서 많은 역구가 수행되었고, 80년대 이후 건설된 대부분의 하수처리장에서 용존산소 농도 제어를 비롯한 기본적인 제어를 실제로 적용하고 있다. 그러나 현재까지 국내에는 하수처리장에 자동 제어가 적용된 경우가 없으며, 현장 적용은 몇몇 폐수처리장에 국한된다. 그러나 자동 제어를 통해 얻을 수 있는 이득이 매우 크다는 것이 명백하고, 현재 각 대학 연구에서 활발하게 연구를 수행하고 있으므로, 가까운 장래에 많은 하·폐수처리장에 자동 제어가 광범위하게 도입될 것으로 기대된다. Operational control and automation of sewage works is a worldwide tendency. By introducing automatic control, many benefits like improvement of efficiency and stability, consistent operation an operational cost saving, can be obtained. Lots of process studies have been performed from 7,80s in developed countries, and basic control (e. g. DO control) is having been appplied to almost every plants constructed after 80s. In Korea, no large sewage work is automatically controlled till now, while some limited application for wastewater treatment plants are exist. But it is very clear that automatic control holds great porfits and lots of vigorous researches are being conducted in many universities and laboratiories, so widespread introduction of automatic control to sewage/wastewater treatment plant in near future is expected.
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이상하,최재석,이광열,장영수,임인수,허우명,김재구,김범철 강원대학교 부속 환경연구소 2005 Journal of the Environment Vol.2 No.-
To investigate nutrient dynamics of the lake and fish community, both water and fish samples were collected at three different areas (dam site, upper inflowing and downstream of lake outfow) for one year from Sep.2004 to Aug.2005 During the experimental periods, mean concentration of chl, a in epilimnetic layer (0-5m) was 18.5mg^(-3) and transparency ranged from 0.3m to 2.4m, respectively. In nutrient, mean concentrations of TP and TN were 111 mgP m^(-3) and 4.4 mgN L^(-1), respectively. Based on the water quality standard suggested by U.S.EPA(*1976), the trophic state of Lake Doam was classified as eutrophic state. Total number of fish collected in Lake Doam was 9,600 indiveduals in 26 species of 6 family. Sixteen of Korean endemic soecies including H. mylodon, A. signifer, P. tenuicorpa occurred. O. mykiss as introduced fish was also found in Lake Doam. Dominant and subdominant species were P. herzi and Z. platypus that took about 34.6% and 22.5% of total fish composition, respectively. Six species including A. signifer. P. tenuicorpa. and R. kumgangensis were rare in Lake Doam. Pelagic typw of figh commonly occurred at upper regions, whereas benthic type was mainly domenated at downstream area. Therefore, pollution source inflowed from the upper regions did not seriously affect downstream area (Songcheon water system) due to the role of dam as pollutant barrier. In addition high appearance of Comat type of fish that si hybrid between gold fish (C.auratus) and C. auratus was found in the lake, It was unclear the reasons that high prorortion of mutant species apperared in the lake. Further more researches are required in this area.
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Modified Ramp-Reset Waveform Robust for Variable Panel Temperature and its Discharge Characteristics
Jang, Soo-Kwang,Tae, Heung-Sik,Kim, Soon-Bae,Jung, Eun-Young,Suh, Kwang-Jong,Ahn, Jung-Chull,Heo, Eun-Gi,Lee, Byung-Hak,Lee, Kwang-Sik The Korean Infomation Display Society 2006 Journal of information display Vol.7 No.1
By the voltage threshold (Vt) close-curve measurement method, the changes in the discharge characteristics such as a firing voltage and IR emission among the three electrodes were examined relative to the low or high panel temperature ranging from -10 to $80^{\circ}$. The variation in the panel temperature was found significantly influence the surface discharge between the MgO surfaces rather than the plate gap discharge between the MgO and phosphor layers. Based on this experimental observation, a modified reset waveform that alleviates the surface discharge during a ramp-up and -down period was deeloped. By adopting the proposed reset waveform, a stable address discharge could be obtained irrespective of the panel temperature variation.
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