• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.15 no.2
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• pp.55-60
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• 1979

The forming and design method of single power factor meter is suggested and the sensitive phase angle detect circuit of current and voltage of load was dealt with. In this paper, in order to control and detect of phase angle of the current and voltage, operational amplifier comparator circuit and R-C phase shift circuit was used, and to detect the controlled voltage wave form, the transister chopper pair circuit was used. The test result of this power factor meter was good and reliable at the full range of power factor.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.6
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• pp.403-410
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• 2000

This paper deals with a study to improve the performance of Moving Coil type Linear Oscillatory Actuator (MC-LOA) considering unbalanced magnetic circuit. MC-LOA has an unbalanced magnetic circuit due to its asymmetric structure. In this type of LOA, the airgap flux density tends to have different magnitude along mover's displacement and the current directions. The above property causes eccentric of displacement center and interferes with the proper oscillation of LOA. Therefore, this paper presents two models having the unbalanced magnetic circuit and the other balanced by the saturated core. In order to compare the characteristics between the two models, a characteristic analysis for both the basic model and the improved model is performed by their dynamic analysis composed of kinetic and electric equations and Finite Element Method (FEM). The propriety of the improved model is verified through the experimental results.

• The Journal of Engineering Geology
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• v.4 no.2
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• pp.207-218
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• 1994

The natural constants of moving coil type geophone can be determined by free impedance and step force method. The former method was desirable for the measurement of natural frequency($f_o$), inertial mass(m) and damping factor($h_o$), but the latter method for sensitivity(G). In particular, the value by the latter method should be corrected for the noise by the long period movement of measurement device. The results of frequency characteristics from these constants operate the accelerometer and displacement system in the boundary of natural frequency.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.1
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• pp.19-26
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• 1999

A moving-coil-type linear motor, designed and fabricated, is consisted of the NdFeB permanent magnets with high specific energy as the stator, a coil-wrapped nonmagnetic hollow rectangular structure and an iron core as a pathway for magnetic flux. The interaction between permanent magmet and armature fie1d, so called "push/pull effect", is to shift the airgap flux density variation due to the magnet alone by a certain amount. Thrust therefore is shift downward or upward. The push/pull effect was presented through the FEM analysis and the static tests. We compared the thrust obtained through the FEM analysis with the static tests. Finally, we present the linearity and correction coefficients of the thrust in consideration of the push/pull effects.l effects.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.196-199
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• 1998

LDM(Linear DC Motor) are used in high speed, high-precision position control system. Because of these advatages, LDM has already used in the motor of pen-recorder, magnetic-disk devices. Under the limited dimension, we propose the design method of LDM by magnetic circuit. In this paper, a relation between the thrust constant and size of a LDM that is moving coil type with unipolar is described, which is defined as a simple relational equation. To maximize the rate of thrust to the volume of LDM, the magnetic flux density in the yoke is adjusted to the value of magnetic equation. By the magnetic field analysis(FEM), the validity of the equation is confirmed.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.3
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• pp.180-187
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• 2000

A moving-coil-type linear oscillatory actuator(LOA) consists of the NdFeB permanent magnets with high specific energy as the stator, a coil-wrapped nonmagnetic hollow rectangular structure. The LOA system was represented by the voltage equation of coil and the mechanical equation of motion. This set of equations was manipulated in state-space form. The EMF constant kE of equation parameters in state-space form can be obtained by using the induced voltage in armature coils at open circuit test. kE and other parameters provide the system matrices and transfer function for frequency response and dynamic simulation. Voltage source inverter-fed LOA is examined aiming to compare with results of simulation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.11
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• pp.713-719
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• 2000

This paper presents an approach toward improving the performance of Moving Coil Type Linear Oscillatory Actuator (MC-LOA) with the application of Finite Element Method (FEM) to a simple control system. MC-LOA has an unbalanced magnetic circuit due to its asymmetric structure and there is a different flux distribution on the air-gap along the current direction. The interaction driven by two fluxes between the Permanent Magnet (PM) and the current causes the unbalanced thrust and interferes with the proper oscillation of MC-LOA. In order to solve the above problems and improve the driving performance, it is necessary to analyze the rate of the unbalanced thrust according to the current direction by using FEM. Then, the analysis results are used to determine the input currents for both directions. Controlling the input currents can be easily achieved by a simple control system, such as Pulse Width Modulation (PWM), without complex units. The validity of the approach is verified by the experimental results.

• Proceedings of the KIEE Conference
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• summer
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• pp.375-377
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• 2004

22.9kV급 가공배전선에서의 뇌격현상은 직접측정이 어렵기 때문에 지금까지 절연협조수준의 도출은 수치적인 모의해석과정에서 얻어진 과전압강도를 근거로 하고 있다. 대표적인 모델에 대해서 만이라도 실측자료를 확보할 수 있다면 해석과정의 정확도를 높이는 중요한 전기가 될 수 있다. 이러한 가공배전선로의 뇌격현상을 측정하기 위한 상용설비를 이용한 경제적 측정시스템을 구성하였다. 접지회로에서 발생하는 과전압으로 인한 인명뿐 아니라 계측설비의 안전성도 확보하고 과 경제성확보를 위하여 전주 중간에 장시간용 UPS 및 파형측정설비를 2중 차폐함 안에 넣어 1점 접지상태가 되도록 고정하고 측정point에 HV divider 및 로고스키코일을 설치하여 한 지점에서의 측정회로를 구성하였다. 전체적으로 뇌격전류 주입 위치에서부터 3지점을 선정하여 측정설비를 설치하고 경제적인 Rs485 multi-drop 회로를 구성하여 통신망을 확보하였다. 직렬통신망에는 뇌격시험 시 발생하는 과전압에 대한 보호회로로서 간단한 수동식 개폐회로를 구성하였다. 측정파형을 전체적으로 전송받는 속도가 약간 늦기는 하나 간단한 data acquisition program을 사용하여 전체 측정회로를 가동시킬 수 있었다.

• Journal of Veterinary Clinics
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• v.31 no.3
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• pp.223-225
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• 2014

A 8-year-old, castrated male Maltese with difficulty in opening his mouth was presented. Masticatory muscle myositis (MMM) was diagnosed by 2M antibody test. After treatment of MMM with corticosteroids, range of jaw motion improved and was almost normal at 5 months. In dogs with MMM, early detection and aggressive immunosuppressive therapy are required to improve the prognosis.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.5
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• pp.241-248
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• 1999

Recently, many linear motion generators and motors are rapidly finding applications that ranges from short stroke linear motion vibrators, such as dynamic cone type loudspeakers to stirling engine driven linear reciprocating alternators, compressors, textile machines etc. The stroke-length may go up to 2m, and the maximum speed is in the range of 5 to 10m/s with oscillating frequency as high as 15 kHz. Therefore, the linear oscillating actuators(LOAs) may be considered as variable speed drivers of precise controller with stoke-length and reversal periods during the reciprocating motion. In this paper, the design, fabrication, experiments, and extraction of control parameters of a moving coil type LOA for driving of linear reciprocating motion control systems, are treated. The actuator consists of the NdFeB permanent magnets with high specific energy as the stator produced magnetic field, a coil-wrapped nonmagnetic hollow rectangular bobbin structure, and an iron core as a pathway for magnetic flux. Actually, the design is accomplished by using FEM analysis for the basic configuration of a magnetic circuit, and characteristic equations for coil design. In order to apply as the drivers of a linear motion reciprocating control system, the control parameters and circuit parameters, such as input voltage-stoke, exciting frequency-stoke, coil inductance and so on, are extracted from the analysis and experiments on concerning a fabricating LOA.