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線形特性을 갖는 Thermistor 溫度-電壓 Transducer 에 關한 考察
鄭東洙 군산대학교 1984 群山水産專門大學 硏究報告 Vol.18 No.3
A new technique to linearize the temperature-voltage relationship of the logarithmic network using one thermistor is proposed. An analytical expression for the linearity condition is obtained and demontrated experimentally. In this paper a thermistor-resistor log network (parallel combination) operating in conjunction with a logarithmic amplifier has been shown to disply linear temperature-voltage relation over a much wider range of temperature (-25℃ to 125℃) with reasonally good response linearity, reliability, and overall improved operational performance. The experimental circuit exhibits excellent thermal stability for ambient temperature variations. Analytically, the relative departure output voltage (Vo(T)) versus temperature(T) curve from the ideal linear response is expressed as relative departure from linearily in persent. A notable feature of the proposed circuit is that the power dissipation in the thermistor is quite low and decreases with increasing temperature thus avoiding a self heating problem in the thermistor. The circuit is simple and ease to compose.
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Computer Algorithm에 依한 Thyristor Inverter 出力의 Harmonic Elimnation에 관한 硏究
鄭東洙 군산대학교 1985 群山水産專門大學 硏究報告 Vol.19 No.3
The theoretical problem of eliminating harmonics in output waveforms of the single-phase half bridge inverter is proposed. The methods for eliminating a fixed number of harmonics in the half bridge inverter output waveforms are generalized, and solutions are presented for eliminating up to two, five harmonics. Numerical analyses are applied to solve the nonlinear equations of the problem on the computer. After computer processing, the following problems came to existance. 1.Implementation difficulty due to unbalancing between the computer speed and SCR switching turn-on/off time. 2.The switching angle variations depend on load property. 3.Failure to about some initial guess. The results show the feasibility of obtaining practically sinusoidal output waveform.
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보문 오십천의 (五十川) 수서곤충군집에 (水棲昆蟲群集) 관한 연구
정동수,김동상,윤일병,변종욱 ( Dong Soo Jung,Dong Sang Kim,Il Byong Yoon,Jong Uk Byun ) 한국하천호수학회 1983 생태와 환경 Vol.16 No.1·2
The present study has been made on the aquatic insect community in the Osib River during the period from May 9 to July 11 in 1982. The results are as followss; 1. The aquatic insects in the Osib River are composed of total 85 species, 55 genera, 29 families in 9 orders. 2. The numbers of species according to order are listed in order of abundance as follows: Ephemeroptera: 34 species, 15 genera in 8 families Trichoptera: 18 species, 14 genera in 7 families Diptera: 18 species, 12 genera in 4 families Coleoptera: 5 species, 4 genera in 3 families Plecoptera: 5 species, 5 genera in 2 families Hemiptera: 2 species, 2 genera in 2 families Odonata: 1 species, 1 genus in 1 family Megaloptera: 1 species, 1 genus in 1 family Lepidoptera: 1 species, 1 genus in 1 family 3. The percentages of individual numbers/m² according to order in the Osib River are as follows: Ephemeroptera 48.1% Trichoptera 37.5% Diptera 13.2% Others 1.2% 4. The dominant species differ with stations in the upper stream, but those in the main stream are Stenopsyche marmorata. 5. The species diversity indices of each station range from 0.32 to 3.80. Those of station 4 are lowest. 6. Cheonduri(St.4) is much polluted station due to the waste water and the coal dust from coal mines and the drainage from Dogye Eup, So that the aquatic insects collected at that station are only 4 species of Diptera and the species diversity indices are very low.
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