• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제12B권1호
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• pp.19-23
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• 2002

This paper investigates the influence of various stator pole shapes and yoke structures in Switched Reluctance Motors (SRM) on the mechanical behavior caused by the electromagnetic farce. The stator part in SRM produces most vibration. The geometric design of the stator is therefore necessary to reduce the vibration. Based on electromagnetic and structural Finite Element Method (FEM), the free and farced vibrations for the various structures of SRM with 6/4 poles are analyzed. Then a less vibration stator structure is proposed. Some of numerical computations for a prototype motor are verified by experimental results.

• Proceedings of the IEEK Conference
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.551-552
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• 2008

This paper presets a results of frequency response in variation of wire bonding length. A gold ball bonding is used as a wire bonding process, and a DPDT(double pole double thru) switch is adapted as a device for test. Wire length is ranged from 442um to 833um and a measured frequency range is from 1 GHz to 6 GHz. Little difference are measured in insertion loss and return loss depending on wire length. Measured S21 and S11 are -0.58 dB and -17.7 dB, respectively. S21 insertion loss is rising up and S11 insertion loss is falling down as the frequency is increased.

• Journal of Korean Elementary Science Education
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• 제17권1호
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• pp.105-112
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• 1998

It is well known that making electric motors is very difficult in chapter 2, "Electric Current and Magnetic Field", natural science textbook 6-1 in primary school. In the present paper, we propose a new and successful method for making them. The most important point is that iron cores are not used in making electromagnets. This resolves the problem that both poles of electromagnet can be attracted by any pole of permanent magnet because of iron core in the electromagnet. The thick enamel wire is used as arms of armature so that they can support the electromagnet stably and we can reliably strip off the skin of the enamel wires, completely for one end and half for the other end of the enamel wires coming from the electromagnet. In addition, we suggest the ring-type support made of aluminum foil and the M-shaped support made of thick enamel wire that can substitute for the M-shaped copper wire support for armature. armature.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 한국전자파학회 2002년도 종합학술발표회 논문집 Vol.12 No.1
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• pp.132-135
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• 2002

A RF amplitude equalizer is designed to improve in-band flatness of Rf filters and/or systems using two dielectric resonators and a 90$^{\circ}$ hybrid. The equalizer has good return loss characteristics and V shaped S$_{21}$ response in passband which is suitable to compensate the ripple degradation due to insufficient quality factors of used resonators or narrow band width of filters or systems. After being connected to the equalizer, a 5-pole BPF at 1957MHz, which has 10 MHz bandwidth and 6㏈ ripple, shows only 1.8㏈ in-band ripple and good in- and out- band matched responses within used hybrid bandwidth without additional matching networks.

• Journal of the Korean Society for Precision Engineering
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• 제25권3호
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• pp.83-92
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• 2008

This paper develops the theory for a fault-tolerant, permanent magnet biased, homopolar magnetic bearing. If some of the coils or power amplifiers suddenly fail, the remaining coil currents change via a novel distribution matrix such that the same magnetic forces are maintained before and after failure. Lagrange multiplier optimization with equality constraints is utilized to calculate the optimal distribution matrix that maximizes the load capacity of the failed bearing. Some numerical examples of distribution matrices are provided to illustrate the theory. Simulations show that very much the same dynamic responses (orbits or displacements) are maintained throughout failure events (up to any combination of 3 coils failed for the 6 pole magnetic bearing) while currents and fluxes change significantly. The overall load capacity of the bearing actuator is reduced as coils fail. The same magnetic forces are then preserved up to the load capacity of the failed.

• Journal of the Korean Institute of Telematics and Electronics B
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• 제32B권12호
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• pp.1572-1580
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• 1995

In this paper, a modified Chebyshev low-pass filter function is proposed. The modified Chebyshev filter function exhibits ripples diminishing toward .omega. = 0 in the passband. So, the modified filter function is realizable in the passive doubly-terminated ladder network for the order n even or odd, thus lending itself amenable to active RC or switched capacitor filters through the simulation techniques. Besides the passive doubly-terminated ladder realizability, lower pole-Q values of the modified function are accountable for improved phase and delay characteristics, as compared to classical function. We have designed the 6th order passive doubly-terminated network using the modified function. And then a continuous-time DDA(Differential Difference Amplifier) filter, which has no matching requirement, is realized by leap-frog simulation technique for fabrication. In the HSPICE simulation results, we confirmed that the designed continuous-time DDA filter characteristics are agreement with the passive filter.

• Journal of the Korean Institute of Telematics and Electronics
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• 제18권6호
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• pp.38-43
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• 1981

In this paper an actively compensatedfinite gain amplifie. (FGA) with positive gain using 4 operational amplifiers and resistors is propo sod, and an application is considered in an active RC filter. By cancelling the effect of the GB's up to the third-order term of s on the transfer function, the proposed FGA has the extended frequency range over that of the FGA using 3 operational amplifiers. When this FGA is applied to an active RC filter with Pole frequncy of 100kHz, the magnitude error of the frequency characteristics of the filter is less than 2%.

• Proceedings of the KSR Conference
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1460-1465
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• 2007

In this paper, the conventional linear induction motor(LIM) used in propelling the MAGLEV in Korea is redesigned in order to reduce its weight. The specifications of the newly designed model for base speed, acceleration, rated thrust and maximum output is respectively 45km/h, 4.0km/h/sec, 5,200[N] and 65 [kW]. Weight reduction effect of the LIM according to the change of pole number from 8 to 6 is shown. Equivalent circuit analysis considering end effect and finite element method are used for the analysis of the redesigned model. Finally the weight reduction ratio of the newly designed LIM to the conventional model, thrust, attraction force, line current, temperature rise, flux density distribution are presented.

• The Bulletin of The Korean Astronomical Society
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• 제35권1호
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• pp.77.1-77.1
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• 2010

I summarize highlights from extragalactic research activities performed with AKARI infrared space telescope. The main emphasis will be given to the works carried out by Korean astronomers. The activities span a wide range of topics, such as MIR properties of nearby galaxies in cluster environment, MIR diagnosis of star-forming galaxies at z=0 through z=2 in the North Ecliptic Pole (NEP) survey field, the Extended Groth Strip (EGS), and the First Look Survey (FLS) field, and the NIR spectroscopy of Luminous Infrared Galaxies (LIRGs) and Active Galactic Nuclei/Super-massive Black Holes at low redshift as well as near the re-ionization epoch of z~6. I describe FIR and MIR all sky data which can be used as a precious resource for extragalactic research, and other future and ongoing works with AKARI. These AKARI results will form a strong basis for future studies using other facilities, such as infrared surveys with UKIRT, FIR study of dusty universe with Herschel, and the SPICA mission.

• Journal of Institute of Control, Robotics and Systems
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• 제17권12호
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• pp.1266-1272
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• 2011

For way-point tracking of an autonomous underwater vehicle, a state feedback controller was designed by using pole placement scheme in discrete time domain. In the controller, 4 state variables were used for regulating the depth of the vehicle in z direction, and 3 state variables, for steering the vehicle in xy plane. Assuming constant speed of AUV, we simplified the design of the way-point tracking system. The proposed controller was simulated by MATLAB/Simulink using 6 degree-of-freedom nonlinear model and its performance of way point tracking was shown to be fulfilled within 1 m, nevertheless the proposed controller is quite simple and easy to implement compared to sliding mode controller.