• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.51 no.6
• /
• pp.276-283
• /
• 2002

This Paper Presents the method for detecting a partial discharge(PD) using an electromagnetic wave measured by an antenna. The various electromagnetic waves are measured in the laboratory and wavelet transform, which is provides a direct quantitative measure of spectral content in the time-frequency domain, are applied for identifying the property of electromagnetic waves. Also, the statistical method and self-organizing feature map(SOFM) are applied for the pattern recognition of electromagnetic waves. The proposed method is shown to be useful for detecting electromagnetic waves emitted for PD in test data.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.26 no.6
• /
• pp.454-461
• /
• 2021

To control the torque of the IPMSM, a lookup table is generally used in control system because of its nonlinear characteristics. However, the method of generating the lookup table data has the disadvantage of having difficulty accurately analyzing the changing parameters, generating the current or magnetic flux map is complicated and long test time taken due to motor temperature differences at each test points. In this paper, on the basis of the electromagnetic field design of IPMSM, we devised an electromagnetic field-based magnetic flux map model that can compensate for the pre-generated magnetic flux map through a quick and simple test.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.15 no.1
• /
• pp.81-88
• /
• 2004

Turbo code has been adopted in the 3GPP standard, since its performance is very close to the Shannon limit. However, the turbo decoder requires a lot of computations and the amount of the memory increases as the block size of turbo codes becomes larger. In order to reduce the complexity of the turbo decoder, the Log-MAP, the Max-Log-MAP and the sliding window algorithm have been proposed. In this paper, the performance of turbo codes adopted in the 3GPP standard is analyzed by using the floating point and the fixed point implementation. The efficient decoding method is also proposed. It is shown that the BER performance of the proposed method is close to that of the Log-MAP algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.24 no.4
• /
• pp.417-425
• /
• 2013

Digital communication technology have been focused on the higher data efficiency and the effective coding of information. Also, it is very important to improve security and minimize the interference of the external sources, Chaos communications system is studied to improve security and minimize the interference by effective encoding of information in the nonlinear systems such as DCSK(Differential Chaos Shift Keying) and CDSK(Correlation Delay Shift Keying). In this paper, we evaluate anti-jamming performance of chaos communications system using the DCSK and CDSK system. The simulation results show that the Gauss iterated map has better BER performance than the other maps(tent map, logistic map, Henon map). Also, DCSK and CDSK system can get the better anti-jamming performance by applying different chaotic maps.

• The Journal of the Korea Contents Association
• /
• v.21 no.2
• /
• pp.431-436
• /
• 2021

In this study, a new shielding method was applied to an accessory device that produces electromagnetic waves in the magnetic resonance room to prevent the generation of artifact caused by electromagnetic waves. The research method applied a new shielding made of metal plating fiber to patient surveillance CCTVs without shielding technology, and obtained and evaluated noise map when the power was not cut off and when the new shielding technology was applied without shutting down the CCTV. As a result of the study, it was found that there was at least one group with significant differences. Type I and type III belonged to group 1 while type II belonged to group 2 in the Post-hoc analysis, which meant blocking power of the CCTV and the applying new shielding technology were in the same group. In conclusion, if electromagnetic waves are generated due to additional accessories in the scanning room, the shielding material proposed in this study should be applied which enables the electric state become similar to type I, not generating noise, thereby preventing the artifacts caused by electromagnetic waves.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.1957-1962
• /
• 2003

In order to design the phantom of heart, we have developed the multi-dipole current source system. Such a one be clue to the various motion of heart. The magnetocardiograph (MCG) system for diagnosing the disease of the heart due to an analysis of the heart signal. The multidipole current source system be built by microprocessor. We use the shield room to obtain a good experimental result. Then the signal acquired is mixed with a background noise, through a filtering extracts a pure signal. The pure signal such a heart phantom is analyzed by an electromagnetic map.

• Journal of the Korean Magnetics Society
• /
• v.26 no.2
• /
• pp.55-61
• /
• 2016

This study proposes the design algorithm of an electromagnetic linear actuator with a divided coil excitation system, such as the colenoid (COL) system, using the equivalent magnetic circuit (EMC) method. Nowadays, the clamping device is used to hold workpiece in the electrically driven chucking system and is needed to produce a huge clamping force of 40 kN like hydraulic system. The design algorithm for electromagnetic linear actuator can be obtained using the EMC method. At first, the parameter map is used to decide the slot width ratio in the initial design. Next, to make the magnetic flux density uniform at each pole, the pole width is adjusted by the pole width adjusting algorithm with EMC. When the dimensions of the electromagnetic linear actuator are decided, the clamping force is calculated to check the desired clamping force. The design results show that it can be used to hold a workpiece firmly instead of using a hydraulic cylinder in a chucking system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.25 no.5
• /
• pp.607-617
• /
• 2014

This paper proposed the M&S(Modeling & Simulation) method of channel characterization of satellite communication in the operating area of satellite OTM(On-The-Move) terminal. In M&S, received signal profile was acquired by HTZ warfare software which uses 3 dimensional map including building, road information and geographical features, and then was analyzed statistically. And a received signal profile and its statistics from M&S data were compared with those from measured data. The research showed that the simulated received signal profile matched the measured one about 74.8 percent and simulated statistics matched well as roadside trees were excluded.

• Journal of the Korean Magnetics Society
• /
• v.22 no.6
• /
• pp.210-215
• /
• 2012

The absorption performance of a metal-backed single layered electromagnetic wave absorber is optimized at matching conditions of thickness and frequency indicating the maximum returns loss of incidence electromagnetic wave in the contour map. These matching conditions are obtained by applying the electromagnetic impedance to the transmission line theory, which depend on the complex permeability and complex permittivity of absorber material. The magnetic materials with high permeability can enhance the matching thickness condition to the wide frequency range based on the decrease of permeability with frequency and it can be used as a wideband electromagnetic wave absorber material. Therefore, the magnetic materials with higher saturation magnetization and lower permittivity than NiZn ferrite can be applied to the wideband electromagnetic wave absorber in order to satisfy the newly enforcing the electromagnetic compatibility regulation in the future.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.9 no.2
• /
• pp.211-218
• /
• 1998

In this paper, we analyze various errors in prediction results of ray tracing propagation model for microcellular environments. It is shown that improper electrical parameters of building materials and limitations of diffraction orders can cause high errors in prediction results. Especially, the effect of errors in building database on prediction results is considered in detail. It is also shown that the prediction error increases as the resolution of building map data is getting worse, and the error is analyzed depending on LOS and NLOS domains. Based on the results obtained by the analysis developed in this paper, 5 m resolution is suitable for the building map data if the maximum prediction error is required to be below 6 dB.