• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2328-2330
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• 2002

Electricity living body formation operation appliance is using most imports until present. And, because electricity living body formation operation appliance is too expensive, it becomes burden to buy in small scale hospital. Also, problem that economical damage by income is added follows. Therefore this treatise developed electricity living body formation operation appliance by home production. Ultra high frequency eruption circuit used LC circuit, and output frequency is possible to 8 [MHz], and output voltage amplified maximum 800 [V]. This operation appliance could display size of fixed current.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2064-2066
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• 1998

The development of the high-frequency induction-heating for 1800kW power range intend to make localization at forging and rolling mill part by technical innovation. And, the development makes to increase our's competitive power at technique, quality and cost. This paper describes the heart of high-frequency induction-heating technique, switching technique, a few problem in common using as an unsatisfied technique, load adjustment technique, system control, diagnostic system and auto-interface etc.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1647-1649
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• 1998

This paper describes the power frequency voltage and its countermeasure when a 765 kV transmission line is directly connected to a 345 kV line and operated at 345 kV voltage. The summary of this result is as follows : The western route of 765 kV transmission line doesn't need any countermeasure to reduce the power frequency voltage at the receiving end. The eastern route of 765 kV transmission needs 100 Mvar(3 phase) capacity of shunt reactor at the receiving end to reduce the power frequency voltage. The use of shunt reactors in the 765 kV transmission lines has unexpected problems, one of which is induction of high voltages on a de-energized circuit of two parallel lines. This paper examined the problem of resonance on two parallel transmission circuits in one routes.

• Structural Engineering and Mechanics
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• v.31 no.5
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• pp.481-506
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• 2009

The present study is concerned with the stochastic linear free vibration study of laminated composite plate embedded with piezoelectric layers with random material properties. The system equations are derived using higher order shear deformation theory. The lamina material properties of the laminate are modeled as basic random variables for accurate prediction of the system behavior. A $C^0$ finite element is used for spatial descretization of the laminate. First order Taylor series based mean centered perturbation technique in conjunction with finite element method is outlined for the problem. The outlined probabilistic approach is used to obtain typical numerical results, i.e., the mean and standard deviation of natural frequency. Different combinations of simply supported, clamped and free boundary conditions are considered. The effect of side to thickness ratio, aspect ratio, lamination scheme on scattering of natural frequency is studied. The results are compared with those available in literature and an independent Monte Carlo simulation.

• The Journal of the Acoustical Society of Korea
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• v.18 no.4E
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• pp.31-36
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• 1999

Circulant Feedback Delay Networks (CFDN's), whose feedback matrix is circulant to control the stability of system and time-frequency response easier than unitary one, were recently proposed. However, the drawback of this structure is that the flatness of the frequency response of CFDN's is not enough and it is difficult to adjust the placement of zeros to decrease this problem. Therefore, we propose Modified CFDN's (MCFDN's) consisted of a general recursive filter and CFDN's to maintain maximally the impulse response of CFDN's and improve the flatness of frequency response without adjusting the placement of zeros. The delay unit of a general recursive filter's feedback loop is replaced by CFDN's, are omitted the direct path. We represent the usefulness of MCFDN's to build artificial reverberators and the main parameter to determine characteristics of MCFDN's in this paper.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.956-959
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• 2003

In the semiconductor and the optical industry a new transport system which can replace the common system is required. The common systems are driven by magnetic field and conveyer belt. The magnetic field damages semiconductor and contact force scratches the optical lens. The ultrasonic wave driven system solve these problem. In this paper the object transport system using the excitation of ultrasonic wave is proposed. The experiments for finding the optimal excitation frequency, finding phase-difference between two ultrasonic wave get orators are performed. The effect of transporting speed according to the change of weight and amplification voltage are verified. In addition, the system performance for actual use is evaluated.

• Journal of the Earthquake Engineering Society of Korea
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• v.18 no.4
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• pp.193-200
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• 2014

This paper examines the pounding problem between adjacent decks subjected to strong earthquakes. The elastomeric bearings in an isolated bridge reduce the stresses on the superstructure and cushion the impact by transferring smaller seismic forces to the substructure. On the other hand, these bearings also allow large horizontal displacement of the superstructure due to seismic forces. Bridges having various supporting soil conditions and different frequency ratios between adjacent decks are investigated by numerical analysis. In the analysis, decision making is conducted whether the collision took place or not and, the magnitude of pounding force and the duration time of collision are obtained and the results are discussed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.4
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• pp.483-490
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• 1998

The reflectivity of a grid ferrite electromagnetic wave absorber is analyzed using finite difference time domain (FDTD) method, which is usually used in anechoic chambers for EMI / EMS test. The frequency dispersive characteristics of ferrite medium and its boundary condition are modeled using magnetic flux in addition to E- and H-fields. By applying Floquets theorem, FDTD analysis of the grid ferrite absorber with periodic infinite array is simplified as a unit cell problem. The method of homogenization which is mainly utilized in the calculation of absorber reflectivity as a low frequency technique takes only into account volume fraction of the unit cell of the absorber except for the structure of medium geometry. However, the presented method in this paper can analyze the geometry effect of the unit cell with its medium characteristics up to high frequency region.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.471-475
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• 1995

This paper deals with the aliasing problem minimized by using an analog low-pass prefilter have a sampling frequency of 18000 Hz is designed and describes to extract their fundamental frequency components by AFT filter. And them distance relaying algorithm based AFT filter is computational simple, good frequency response and fast convergence in calculation of system apparant impedance. We performed off-line simulation using data from EMTP.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.127-133
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• 2001

The flexibility of long reach manipulators presents a difficult control problem when accurate end-point position is required. Input shaping by convolving system commands with impulse sequences has been shown to be an effective method of reducing residual vibrations in flexible systems. However, existing shapers has been considered robustness for only frequency uncertainty. However, this paper presents new multi-hump convolution(CV) input shaper that could accommodate with the simultaneous variation of natural frequency and damping ratio. Comparisons with previously proposed input shapers are presented to illustrate the qualities of the new input shaper. These new shapers will be shown to have better robustness for the variation of frequency and damping ratio.