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MO이론에 의한 Diels-Alder 반응의 배향성과 반응성의 결정(Ⅰ)
丁學鎭,金一斗,朴聖珪 조선대학교 기초과학연구소 1985 自然科學硏究 Vol.8 No.1
This paper aims to predict the reactivity and the regioselectivity of Diels-Alder reactions of unsymmetical dienes and dienophiles. Frontier orbital theory has been applied to thermal Diels-Alder reaction by means of CNDO/2 and EHT-spd methods. The above reactions are normal electoron demand reaction and the major regioisomer is the para-substituents that is identical with experiments. Four-frontier orbitals and two-frontier orbitals' methods are identical with experimental major regioisomers. Sulfur is a much more polarizing substituent for the dienes than chlorine and cyanoradical. When sulfur is in diene, it shall dominate the regioselectivity. The coefficient polarization of substituted dienes and dienophiles is the same direction. We can predict the major regioisormer as para-substituents.
양승학,김홍렬 湖南大學校 1997 호남대학교 학술논문집 Vol.18 No.2
This paper describes a design of fuzzy logic controller for an education of fuzzy controller with example of steering control of the navigation vehicle. The steering ofvehicle is controlled to pursuit a regerence line. Number of vehicle states related with a reference line is 9 cases. Each cases has a control rule to achieve the aim. Using fuzzy inference engine, fuzzy inference value is obtained, This value cannot be used as a control input directly. Center of gravity(COG) method is used to defuzzification the fuzzy value. Universe of discourse is scaled to [-1. 1] to regulate the real sensing value. Scaling factor Sδ, Sθ, Sφ are used. With varying the factors, the system response is varied. Among the factor Sφ is the most sensitive factor. In this simulation Sφ is not varied. Control rules and Sδ, Sθ can be changed with the user specification. This educational fuzzy simulator will be used to understand a fuzzy logic controller for beginners with user tuning of scale factors.
X-ray용 고주파 공진형 고전압 발생장치에 관한 연구
김학성,유동욱,김현준,원충연 成均館大學校 科學技術硏究所 1995 論文集 Vol.46 No.1
This paper is concerned with High Frequency, High Voltage Generator for X-ray using zerovoltage soft-switching PWM DC-DC power converter by resonant method, which makes the most of the parastic IBC parameters of high-voltage transformer link, for diagonostic X-ray power generator. The converter circuit basically utilizes phase-shift pulse width modulated series resonant full-bridge PWM DC-DC high-power converter operating at a constant frequency;25kHz. The high-frequency switching operation of the inverter has some effective advantages with consist in the physical reduction in size and weight and lowered acoustic noise. The converter output regulation is digitally controlled using DSP(Digital Signal Processor) for obtaining a fast rising time and adjust output voltage within a wide load range. This converter characteristics are evaluated in terms of computer-aided analytical and experimental results.
Young의 간섭실험에서 이중슬릿 앞에 놓인 단일슬릿의 기능에 대한 연구
정성오,김학수 釜山大學校 師範大學 科學敎育硏究所 2009 科學敎育硏究報 Vol.36 No.-
A double-slit experiment was done by using two kinds of single-slits. The light sources were a halogen lamp, Na-lamp and sun light. The interference fringes were observed by photographing the fringes on the screen and exposing a film on the screen position without lens of the camera. The visibility was better when the width of the single-slit was narrower. The distance between the single-slit and the double-slit was varied. As they were closer, the visibility was decreased. In the experiment using a prism, we could observe the interference patterns of all wavelengths in one picture. From this experiment we can suggest that this experiment might be used in the introductory physics laboratory for understanding interference and diffraction of light.
스위치드 릴럭턴스 電動機의 經濟的인 驅動 시스템에 관한 硏究
김기운,김학성,김재문,원충연 成均館大學校 科學技術硏究所 1996 論文集 Vol.47 No.2
In this paper, we studied on the comparisons of drive characteristics between modified C-dump converter and asymmetric bridge converter for a switched reluctance motor drive system. In the experiments, the reliability and control capability of asymmetric bridge converter is superior to that of modified C-dump converter and in terms of the number of devices and the high speed capability, modified C-dump converter shows the improved performance when compared with asymmetric bridge converter. The speed control system is controlled by low cost one-chip microcontroller 80C196KB and EPROM is used for the angle control of SRM.
One-Chip Microcontroller에 의한 Switched Reluctance Motor의 속도제어에 관한 연구
강욱,김학성,류홍제,원충연 成均館大學校 科學技術硏究所 1993 論文集 Vol.44 No.2
The switched reluctance motor(SRM) drive is becoming an attractive candidate for replacing conventional adjustable speed ac and do drive in many industrial and consumer application like pumps, fans, household appliances and automotive actuator etc. The control method of triggering and conduction angle for variable speed drive is presented in this paper. It also describes new work in the area of electronic control of SRM. The control functions and converter switching signals are processed in low cost microcontroller. Experimental verification is provided for 8/6 pole prototype SRM drive.
DSP를 利用한 Phase-shifted PWM 直列共振型 DC-DC 컨버터
김현준,김학성,김세찬,유동욱,원충연 成均館大學校 科學技術硏究所 1995 論文集 Vol.46 No.2
This paper deals with a phase-shifted PWM high-frequency series resonant DC-DC converter using IGBTs. The converter output voltage regulation is digitally controlled using DSP(TMS320C31) for a fast rising time and low ripple output voltage. A PID controller and feed-forward controller is adopted as a controller and implemented on software. Simulation technique are employed to describe resonant converter behavior, which can present system output exactly and calculate in short time, by applying numerical method to the state equation of each equivalent circuit. And the simulation results are verified as compared with experimental results.
전압형 인버터에 의한 直流 스폿鎔接器의 定電力制御에 關한 硏究
김재문,김학성,박성수,원충연,김덕헌 成均館大學校 科學技術硏究所 1996 論文集 Vol.47 No.1
In recent years, there is increasing interests in spot welder with industrial growth of automobile. It makes autowelding and short-time welding possible. Conventional spot welders using AC source bring about the depreciation of welding products, because constant current control makes its workpiece spattered during welding process. In this paper, the constant power control strategy using PI controller is proposed to improve the quality of the welding products. PI controller is implemented by l6bit one chip 80C196KB microcontroller. Simulation and experimental results show that DC spot welder with single phase PWM inverter is effectively controlled by the constant power control method in very short-time.
신경회로망을 이용한 정현파 밴드 히스테리시스 전류 제어기
元忠淵,梁承浩,金世燦,金學成 成均館大學校 科學技術硏究所 1993 論文集 Vol.44 No.1
Current-controlled PWM inverter offers substantial advantages in improving motor system dynamics in high-performance ac drive systems under vector control. Among the various current control techniques, fixed band hysteresis current control has been widely used. A hysteresis controller employing sinusoidal bands has been reported in recent years. In this paper new current control schemes based on neural network for PWM inverter are described, Four types of controllers have been studied and their performance compared with each other. Finally, relevant simulation results are shown to prove the effectivness of the proposed current control scheme.
Soft Switching 방식을 이용한 Active Clamp Mode Forward Converter 설계
원충연,유동욱,김덕헌,김학성 成均館大學校 科學技術硏究所 1992 論文集 Vol.43 No.2
In recent years, a trend of DC-DC converter is studied mainly quasi resonant converter and multi resonant converter such as resonant type. But by using zero voltage and zero current method, these converter have voltage and current stress in the circuits. So the purpose of this paper is to reduce voltage and current stress, and to increase efficiency (about 5∼10%) rather than above converters. Experimental results show that active clamp mode PWM switching forward converter has minimum switching loss and conducting loss. The test results verify the simulation performance.