• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.261-264
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• 1997

A contactless eddy current type braking system is developed to take advantages of the recent brake system which uses hydraulic force can show high efficiency in a certain velocity region, but not in a high velocity region, and has initial response delay time and pressure build-up time which make stopping distance longer. These are the limits of mechanical brake system of a contact type, which makes a concept brake system required. So, in this paper, the contactless brake system .of a inductive current type is chosen instead of hydraulic brake system. This brake system can be used almost forever for being no wear and contributed to lightening weight of a vehicle. Besides, the contactless brake system can be used as that of electric or solar car with anti-lock brake system. The analysis of induced electromotive force and braking torque obtained with theoretical approximate model, the design of a braking system and a nonlinear controller, and the results of simulation of the ABS, experiment are included.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2002년도 춘계학술대회 논문집
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• pp.62-67
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• 2002

While upwelling regions account for only 0.1% of the ocean surface, they yield over 40% of world's fish catch. Thus it is vary important making upwelling region by various methods. This study was performed to find out basic hydrodynamic characteristics (function, stability..,) of artificial upwelling structures. The hydrodynamic characteristics of artificial upwelling structures can be summarized as follows: 1) The falling velocity of blocks was effected size($l_B$) of blocks than incident current velocity( $V_0$). 2) The falling horizontal distance was reduced as induce of stratification parameters and block' size. 3) Generation of artificial upwelling current was effected by size of structures and incident current. When stratification parameters was about 3.0 and relative height(hs/h) of structures was about $0.125{\sim}0.15$, stable artificial upwelling current was generated in the back-side of structures.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1530-1532
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• 2001

The displacement current measuring system used for detecting the dynamic behavior of monolayers at the air-water interface is described. It basically consists of a film balance, a pair of electrodes connected to each other through a sensitive ammeter. Here, one electrode is suspended in air and the other electrode is placed in the water. With Maxwell-displacement-current-measuring method, the phase transitons of Poly-$\gamma$-benzyl p-glutamate (PBDG) on a water surface were detected. Measured surface pressure, displacement current and dipole moment of monolayers of PBDG on the water surface. Also, we measured that compression velocity(30, 40, 50[mm/min]) when the sample spread volume was about 400[ul]. From the result, it is known that current is generated in the range of high surface pressures as compression velocity become faster.

• 한국정밀공학회지
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• 제19권10호
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• pp.107-113
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• 2002

To monitor the torque of an induction motor using current, rotating speed has been measured and used to calculate the slip angular velocity. Additional sensor, however, can cause extra expense and trouble. In this paper, a new algorithm is proposed to monitor the torque of vector controlled induction motor without any speed measuring sensor. Only stator current is measured to estimate the magnetizing current which is used to calculate flux linkage, rotor velocity and motor torque. Graphical programming is used to implement the suggested algorithm and to monitor the torque of an induction motor in real time. To solve the fluctuation problem of estimated torque caused from instantly varying rotating speed of an induction motor, the rotating speed is reconstructed based on the measured current signals. From several experiments, the proposed method shows a good estimation of the motor torque under the normal rotational speed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2070-2072
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• 2002

In this paper, advance angle control is described to drive an industrial low voltage SRM(Switched reluctance motor) for a forklift truck by changing velocity and torque. The high current SRM is designed and its phase resistance and phase inductance are very low to inject high current into the phase windings. In this reason, the current has to be built up in the increasing phase inductance part as soon as possible. Therefore, the phase switch must be turned on before the phase inductance increases, and this angle is called as the advance angle. We analyze the changes of the advance angle as its torque and velocity are changed in the real SRM driving experiment. And we propose the way to improve the SRM performance by using the advance angle control.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 추계 학술논문 발표대회
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• pp.121-122
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• 2014

This study contemplated the descending air current from the smoke layers related to the smoke logging phenomenon in the sprinkler applied design for effective evacuation safety design. As a result, database on the average particle diameter, particle velocity and distribution of sprinkling was obtained and the relationship between the water amount and particle diameter was obtained. Also, in relation to descending air current, the movement of smoke layer to the bottom at the descending air current velocity of 0.6m/s was observed and stable descending air current was observed in existence of fire source over 100kW in size.

• 전기의세계
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• 제30권8호
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• pp.501-508
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• 1981

A novel and simple method of designing the current feedback loop for the velocity controller of an armature controlled dc servo motor is presented. Instead of constructing the usual tight current feedback loop, a loose current feedback loop is suggested in this paper. More specifically, the armature current is not limited to a fixed constant value, but instead the upper bound value is allowed to be variable along with the present motor speed. The control system designed in this manner shows that the motor under control is robust to a wide range of loading conditions and yields a more rapid transient characteristics which is verified experimentally by applying the method in the design of the controller for an Industrial robot.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.385-388
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• 1997

We hate examined the electrical properties of L-${\alpha}$-DLPC Langmuir(L) films by using a displacement current measuring technique with pressure stimulation. Displacement current was generated when the sample spread volume was about 280${\mu}\ell$, 360${\mu}\ell$ and compression velocity was about 30, 40, 50mm/min. Displacement current was generated in the range of gas state, gas/fluid state and fluid state in the course of monolayer compression. From the result, it is known that displacement current is generated in the range of high surface pressures as compression velocity become faster.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.1007-1009
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• 1993

In this paper, The hybrid method in order to reduce the unknown varible for 3D eddy current calculation is proposed. we adopt the current vector potential(T) and the magnetic scalar potential($\Omega$) as field variable, and adopt image charge method for symetric boundary condition in BEM. We apply the hybrid method to electromagnet for levitation system and analyze the charateristics of eddy current airgap flux distribution, attractive and magnetic drag force according to velocity.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제22권4호
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• pp.217-239
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• 2018

This paper examined the MHD and thermal behavior of unsteady mixed convection flow of a rotating fluid in a porous parallel plate channel in the presence of Hall current and heat source. The exact solutions of the concentration, energy and momentum equations are obtained. The influence of each governing parameter on non dimensional velocity, temperature, concentration, skin friction coefficient, rate of heat transfer and rate of mass transfer at the porous parallel plate channel surfaces is discussed. During the course of numerical computation, it is observed that as Hall current parameter and Soret number at the porous channel surfaces increases, the primary and secondary velocity profiles are increases while the primary and secondary skin friction coefficients are increases at the cold wall and decreases at the heated wall. In particular, it is noticed that a reverse trend in case of heat source parameter.