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좌종근 제주대학교 1986 논문집 Vol.23 No.-
This paper discusses a method of determining suitable phase converter throughout the speed range using the criteria of minimum unbalance or minimum negative sequence voltage when a three phase induction motor operate with single phase supply Three equivalent circuits are investigated to determine the capacitance. and it is found that Ishizaki's equivalent circuit is suitable.
試演防止課題의 遂行時間과 檢査間隔이 再生量에 미치는 效果
金佐根 慶北大學校 師範大學 1983 敎育硏究誌 Vol.25 No.-
This study aimed to investigate the effects of the performance time of the distractor task and the test interval on the amount of free recall in Short-Term Memory. (STM) Sixty first-year students in middle school were randomly assigned to one of the four experimental groups as following conditions; (1) receiving 3-seconds of the distractor task to perform and 10-seconds of the test interval, (2) receiving 3-seconds of the distractor task to perform and 120-seconds of the test interval, (3) receiving 18-seconds of the distractor task to perform and 10-seconds of the test interval, and (4) receiving 18-seconds of the distractor task to perform and 120-seconds of the test interval. Projector type tachistoscope (TKK-208) was employed to present subjects with the tasks. The significance of obtained data was tested by the mixed design of 2×2×3(W) ANOVA, and the results were interpreted by one-or/and two-process theory. The conclusions obtained in this study are as follows; (1) the performance time of the distractor task has an effect on the amount of free recall in STM. (2) the test interval does net have an effect on the amount of free recall in STM. (3) the number of trials has an effect on the amount of free recall in STM. (4) the first or second order interaction effects of these variables are not found in this study.
등가회로법에 의한 커패시터 구동 단상 유도전동기의 특성해석
좌종근(Chong-Keun Jwa),김호민(Ho-Min Kim),김도진(Do-Jin Kim) 대한전기학회 2011 전기학회논문지 P Vol.60 No.4
This paper proposes a straightforward method of analyzing the operation characteristics for the capacitor run single-phase induction motor from the traditional equivalent circuit based on the revolving field theory. The proposed method consists of five procedures as follows: mechanical loss segregation, iron loss segregation and calculation of the equivalent circuit parameters, recalculation of parameters of the main winding side, calculation of the auxiliary winding magnetizing reactance and effective turn ratio, and analyzing the operation characteristics for this motor. When the characteristics are analyzed, the segregated mechanical and iron losses are considered as a loss resistance across input terminals of the equivalent circuit for the analysis. The validity of the proposed method is verified from the comparison between the computed results and the experimental ones for the operation characteristics.
단상 유도전동기의 무부하손실을 고려한 등가회로 정수의 결정
좌종근(Chong-Keun Jwa),김도진(Do-Jin Kim) 대한전기학회 2010 전기학회논문지 P Vol.59 No.4
This paper proposes a step-by-step method of determining the parameters of equivalent circuit which is considered the no load losses for the single phase induction motor which has the starting winding. This method is comprised of three steps, and the stator resistance which is measured by the method of voltage drop is treated as constant and the stator and the rotor leakage reactances are assumed to be the same in every step. The test results of no load and locked rotor test are used in the 1st and 2nd step, and the ratings of name plate of the motor are needed in the 3rd step. In the 1st step, the traditional equivalent circuit parameters are directly calculated by no load and locked rotor conditions. In the next step, five nonlinear simultaneous equations for five unknown parameters can be set up by no load and locked rotor equivalent circuits. These equations are solved by using the initial parameters obtained by the 1st step parameters. In the final step, three nonlinear simultaneous equations for rotor winding resistance, leakage reactance and no load losses component resistance can be set up by equivalent circuit under the rated operation. Three parameters are solved by using the 2nd step parameters. Thus, equivalent circuit parameters are gradually refined step by step. The validity of the proposed method is evaluated by comparing the computed values obtained by the equivalent circuit parameters with the experimental values of the load test.
풍력구동 자기여자 유도발전기의 해석 : Newton Raphson법과 정할법의 비교
좌종근 濟州大學校 産業技術硏究所 1996 산업기술연구소논문집 Vol.7 No.1
The Newton Raphson method and the secant method for the steady state analysis of a wind driven self-excited induction generator are presented and compared in this paper. The nodal admittance method which involves simple algebraic calculations is used for this analysis. Very good agreement between the two numerical methods has been obtained on several load conditions, but it is found that the secant method is better than the Newton Raphson method in the number of iteration and the length of program.
左宗根 제주대학교 1981 논문집 Vol.13 No.-
整流回路를 考慮한 單相變壓器 等價回路를 1) 電流의 重複角과 2) 重複角에 의한 電流成分의 影響도 考慮하여 3) 交流側에서 特性을 算定할 수 있도록 構成하였다. 이 等價回路에서 特性을 算定하여 實驗値와 比較한 結果 잘 一致하고 있으므로 整流回路를 가진 變壓器의 特性解析에 有用한 資料가 될 것이다. A steady-state wquivalent circuit of transformer using bridge rectifier in the secondary circuit was investigated. In order to determine this equivalent circuit, the current overlap angle u and the effects of current componets based on u were considered. From this equivalent circuit, the operation characteristics of this system were described and calculated. Some experimental results were compared with calculated value in graphical form.
左宗根 濟州大學校工科大學産業技術硏究所 1997 尖端技術硏究所論文集 Vol.8 No.1
Newton Raphson algorithm using difference method for a wind driven self-excited single-phase induction generator is proposed, when the capacitor is connected to the auxiliary winding and the load to the main winding. This method requires only simple numeric calculations. comparing with other reported methods which contain monotonous and complicated algebraic manipulation. As the computed results, we find that the three difference methods can be applied to Newton Raphson algorithm. Also, the initial guess values and the step size are affected in the number of iterations. Furthermore, the central difference method is better than the forward and the backward difference method in the number of iterations.
左宗根 제주대학교 1980 논문집 Vol.12 No.-
The T-type equivalent circuit constants of transformers with regard to magnetic saturation, are studied. And these constants are determined by measuring both prinary and secondary resistance, and also by the no-load test (at 60% and 100% of rated voltage) and the rated frequency short-circuit test (at 50%, 100% and 200% of rated current). By using these constants, the characteristics are calculated accurately, and the calculated values and measured values are compared.
左宗根 제주대학교 1994 논문집 Vol.39 No.-
풍력으로 구동되는 자기여자 유도발전기가 정격속도로 운전할 때 여자회로의 자기포화곡선을 구간 선형화하여 거의 모든 영역에서 자기여자작용을 일으킬 수 있는 커패시턴스의 값을 구하여 분석하였다. 또한 정격 단자전압을 유지하기 위한 커패시턴스의 값을 구하기 위한 간결한 방법도 제시하였다. 일정 부하, 정격속도 운전시에 대한 분석결과는 다음과 같다. 1) 공극전압이 커질수록, 여자리액턴스가 작아질수록 커패시턴스가 커진다. 2) 주파수가 낮아질때, 높은 단자전압이 필요할 때 큰 커패시턴스가 필요하다. 3) 부하의 종류와 크기에 따라 필요커패시턴스가 다르다. 일정 공극전압, 정격속도, 부하변화시에 정격전압을 유지할때는 부하임피이던스가 증가함에 따라 커패시던스가 작아지고, 주파수도 떨어진다. The loop analysis to predict the terminal capacitance value required for self excitation of an isolated self-excited induction generator supplying a balanced R-L load is investigated. Two nonlinear equations have to be solved to obtain this capacitance value. In this paper a straightforward method is introduced to predict the capacitance requirement for most all of saturated region under constant speed operation. A simple method is also introduced for computing the capactance required for maintaining the preset terminal voltage under the variable load.
左宗根 제주대학교 1985 논문집 Vol.21 No.-
實測資料만에 의하여 變壓器 過度勵磁電流計算을 위한 T型等價回路를 構成하고 回路定數 변화에 대한 影響을 檢討하여 回路定數의 決定方法은 물론 電流計算方法도 提是하였다. 檢討한 決果 1. 回路定數를 決定기 위한 試驗은 1次捲線低抗測定, 無負荷試驗, 短試驗 및 Hysteresis 特性測定이 필요하며 2. r₁의 값은 1次低抗測定 決果値를 25。C로 換算하고 3. r??을 考廬하여 計算하여야 함을 알았다. T-type equivalent circuit, composed by test data, is used to calculate the transient magnetizing currents. Using this circuit, and method of determining circuit parameters considered the effect of the parameters variation as well as the method of computing inrush currents. The results obtained are as follows; 1) To determine the circuit parameters, primary winding-resistance measurement, open circuit test, short circuit test and hysteresis characteristic measurements are required. 2) The value of r₁, measured by primary winding-resistance measurement, should be converted into the resistance at 25。C. 3) The core loss resistance(r??) is necessary to compute the magnetizing inductance.