• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.131-133
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• 2001

Dendrimers represent a new class of synthetic macromolecules characterized by a regularly branched treelike structure. Peculiar features of the dendritic geometry are the large number of end groups as well as the shape persistence in higher generations, approaching spherical geometry. And one of the most peculiar characteristics of dendritic macromolecules is their controlled molecular structure and orientation, which means that they have a practical application in achieving a highly organized molecular arrangement. We attempted to fabricate a G4-48PyA dendrimer LB films containing 48 pyridinealdoxime functional end group that could form a complex structure with metal ions. Also, we investigated the surface activity of dendrimer films at air-water interface. And we have studied the electrical properties of the ultra-thin dendrimer LB films. The electrical properties of the ultra-thin dendrimer LB films were investigated by studying the current-voltage characteristics of metal/dendrimer LB films/metal (MIM) structure. And rectifying behavior of the devices was occurred in applied field.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.155-158
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• 1989

This study aims to present grounding design techniques of high resistivity sites, develop a program for grounding mesh design and prove the effectiveness of the program by comparison between simulation results and field measurements.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.1954-1956
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• 1997

In this paper, a variable structure current control scheme for field-oriented induction motor drive is presented. The current controller based on space voltage vector PWM scheme consists of feedforward, decouple and variable structure control. The proposed current controller tracks reference value quickly, has robust property against parameter variation and disturbance, reduces switching frequency and improves performance of induction motor drive. Finally, the proposed current controller is verified by digital simulation

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.171-173
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• 1995

Slot field harmonics exist in air gap due to inevitable slot constructure of induction motors. They give rise to noise by the electromagnetic vibration and mechanical pulsation. We calculate the slot field harmonics for varying the ratio of slot width vs teeth pitch using the carter's coefficent. We computate the flux density in air gap by FEM(Finite Element Method) and analyze it in frequency domain using DFT(Discrete Fourier Transform). We develop the new algorithm mixing FEM with DFT.

• Magazine of the Korean Society of Agricultural Engineers
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• v.25 no.4
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• pp.38-49
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• 1983

This study was intended to develop a curriculum for the agricultural engineering technology, and that on confidence with junior college characteristics. In order to per- formance with this study, job cluster was analyzed on 28 parts in respect to the agricultural engineering field and questionnaire was investigated to the field including in alumni 181, students 537, professional workers 174 and professors 54. The results from the above analysis and investigation can be summarized as follows. 1. According to the investigation on degree of important subjects from the questionnaire, it is presented at mathematics 43%, physics 36% in students and 32%, 12% in professional workers. Considering from this results, it is desirable that primary subjects should be forced. 2. In comparing with fundamental major subjects and applied it, it is presented at that 41%, this 34%, in the total investigations. It can be found that in the degree of requirement, this is lower than that among the major subjects. 3. In investigation to the degree of requirement in the experiment and practice, it is presented at surveying 63%. Soil mechanics 14%, materials 13%, hydraulics 9% in order, in total inspection. 4. From investigation to the degree of requirement on the subjects of established newly, it is presented at majoring and living English 64%, E.D.P.S 30%, in the total questionnaire. Judging from the results, it seems that the foreign language is necessary to technician more and more, for advance to abroad. Also, it is no wonder that make good use of the E.D.P.S. 5 The table 5 is represented the model curriculum from the above results in anaized data on the questionnaire and the job cluster of table 2.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.2
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• pp.67-72
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• 2004

Electro-Rheological(ER) fluids consist of suspensions of fine polarizable particles In a dielectric oil, which upon application of an external electric field control take on the characteristics of the Bingham solid. In this study, the temperature dependence of the viscosity was Investigated for an ER fluid consisting of 35 weight % of zeolite particles in hydraulic oil 46cSt. Thermal activation analysis was performed by changing the ER fluid's temperature from $-10^{\circ}C$ to $50^{\circ}C$. According to the analysis, the activation energy for flow of the ER fluid was 79.6 kJ/mole without applying electric field. On the other hand, with the electric field of 2kV/mm, the linearity between viscosity and temperature was not existed By changing the temperatures the viscosity (or shear stress) versus shear rates were measured. In this experiment shear rates were increased from 0 to $200s^{-1}$ in 2 minutes. Generally, the hydraulic oil 46cSt will be operated at the temperature of about $40^{\circ}C$, thus, the ER fluid's electric field dependence of viscosity was examined at this temperature. Also, an influence of adding the dispersant(Carbopl 940) on ER effect was discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04b
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• pp.108-111
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• 2000

We will illustrate the topographical structure and optical structure of the merocyanine dye LB films obtained by the scanning near-field optical/atomic force microscopy (SNOAM). SNOAM was recognized as a powerful tool to modify the surface as well as to characterize the topography of the surface at atomic resolution, especially for optical reaction materials. SNOAM images showed that the topographical and optical structures of these films were not only depended on the chemical property but also physical property. In the continuous measurement on these dyes, the appearance of near-field optical transmission images showed a certain dependence on the kinds of dyes and the mutual mixing ratios of dyes. These experimental results suggest that there is a certain kind of interaction between these two dyes.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1311-1313
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• 1995

In this paper, We can obtain Electron energy distribution function(EEDF) by using two Differentiators. In addition, We investigate the characteristics of EEDF as function of the position of probe, magnetic field, and pressure.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2088-2090
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• 1997

This paper consists of the speed sensorless vector control of induction motors with the estimation of rotor resistance. In the application of variable-speed induction motor drives, if an inaccurate rotor resistance is used because the rotor resistance can change due to skin effects and temperature variables, it is difficult to achieve a collect field orientation. In this paper, to overcome these difficulties adaptive algorithm is designed for rotor resistance identification. The proposed adaptive algorithm for rotor resistance estimation in the synchronous reference frame is applied by sliding mode current controller satisfing persistent excitation(PE) condition. Adaptive flux observer is here used for the purpose of estimating rotor flux and speed in the speed sensorless scheme. Computer simulations are carried out to verify the validity of the proposed algorithm.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.510-513
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• 1996

This paper consists of the speed sensorless vector control of induction motors with the estimation of rotor resistance. In the application of variable-speed induction motor drives, if an inaccurate rotor resistance is used because the rotor resistance can change due to skin effects and temperature variables, it is difficult to achieve a collect field orientation. In this paper, to overcome these difficulties adaptive algorithm is designed for rotor resistance identification at the beginning of the transient state. And an adaptive flux observer is used for the purpose of estimating rotor flux and speed in the speed sensorless scheme. Computer simulations are carried out to verity the validity of the proposed algorithm.