• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.6
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• pp.959-964
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• 2001

An experimental investigation on the near-field electromagnetic loss of thin copper layers has been presented using microfabricated microwave transceivers for applications to multi-chip microsystems. Copper layers in the thickness range of 0.2$\mu$m∼200$\mu$m have been electroplated on the Pyrex glass substrates. Microwave transceivers have been fabricated using the 3.5mm$\times$3.5mm nickel microloop antennas, electroformed on the silicon substrates. Electromagnetic radiation loss of the copper layers placed between the microloop transceivers has been measured as 10dB∼40dB for the wave frequency range of 100MHz∼1GHz. The 0.2$\mu$m-thick copper layer provides a shield loss of 20dB at the frequencies higher than 300MHz, whereas showing a predominant decreases of shield loss to 10dB at lower frequencies. No substantial increase of the shield effectiveness has been found for the copper shield layers thicker that 2 $\mu$m.

• Progress in Superconductivity and Cryogenics
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• v.8 no.2
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• pp.33-36
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• 2006

Multi-stacked HTS wires are needed to conduct large current in the power application. In this paper, magnetization losses of the multi-stacked YBCO wire and the BSCCO wire have been measured and compared. 4 types of YBCO wires and BSCCO wires, that is, single, 2-stacked, 3-stacked and 4-stacked, have been tested. HTS multi-stacked wires were fabricated using face-to-face type stacking method. Measurements of magnetization loss were performed under various angles of external magnetic field to consider the anisotropic characteristics of HTS wires. The ratios of the magnetization loss by multiple stacking of superconducting wires were presented. Measurements results show that loss reduction ratios have three distinct regions due to the magnitude of external magnetic field, the material of HTS wire and number of stacks.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.4 no.2
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• pp.4-10
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• 1993

In mobile radio communication, propagation paths are time or spacial varying because of the motion of mobile unit. The propagation path loss not only involves frequency and distance but also the antenna height at both the base station and the mobile unit, terrain configuration, and the man made en- vironment. Thhese additional factors make the prediction of propagation path loss of mobile radio signals more difficult. In this paper, it is measured field strenght of mobile radio signals in Daejeon and Seoul area, also calculated local median, 500m sample mean, and stadard deviation. As the result of analysis, it can be seen that propagation path loss of measured data is similiar to predicted field strength, especially local median is dependent upon base antenna height, terrain configuration and the man-made environment. The standard deviation has been noted to lie between 2 and 10 dBuV.

• Progress in Superconductivity and Cryogenics
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• v.9 no.1
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• pp.57-60
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• 2007

Superconducting electric power devices need to stack HTS wires to increase the current carrying capacity. Uniform multi-stacked wires(UMS) which were made of the same HTS wires have been used. This paper shows the magnetization loss of hybrid multi-stacked(HMS) wire made of BSCCO wires and YBCO wires. Five HMS wires, YB(YBCO-BSCCO), YYBB. YBYB, YBBY and BYYB, were made and tested. Magnetization losses of each UMS wire were compared with corresponding HMS wire. Test results show that magnetization losses per unit length of HMS wire are between the corresponding UMS BSCCO wire and HMS YBCO wire below critical magnetic field. Above the critical magnetic field, magnetization losses of HMS wires are larger than that of corresponding both VMS wires.

• Progress in Superconductivity and Cryogenics
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• v.25 no.3
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• pp.38-42
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• 2023

The evaluation of no-insulation (NI) high-temperature superconducting (HTS) typically uses the lumped equivalent circuit (LEC) model. Constant parameters in the NI HTS LEC model accurately predict voltage and central magnetic field at currents below the critical current. However, it is difficult to find constant circuit parameters that simultaneously satisfy the measured voltage and magnetic field under overcurrent conditions. Recent research highlights changes in contact resistance during transient conditions, which may impact power loss estimation in NI HTS coils. Therefore, we confirm the influence of contact resistance changes on loss calculation in the transient state for NI HTS coil. To achieve this, we introduce a measurement data analysis method based on the LEC model and compare it with the LEC model using constant circuit parameters.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.2
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• pp.37-44
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• 2018

Universal soil loss equation (USLE) had been employed to estimate potential soil loss since it was developed from the statewide data measured and collected in the United States. The equation had an origin in average annual soil loss estimation though, it was modified or improved to provide better opportunities of soil loss estimation outside the United States. The equation has five factors, most studies modifying them to adapt regional status were focused on rainfall erosivity factor and cover management factor. While the conservation practice factor (USLE P factor) is to represent distinct features in agricultural fields, it is challenging to find studies regarding the factor improvements. Moreover, the factor is typically defined using slopes. The factor defining approach was suggested in the study, the approach is a step-by-step method allowing USLE P factor definition with given condition. The minimum condition is slope and field location to provide an opportunity for using in any GIS software and to reflect regionally distinct features. If watershed location, slope, crop type, and mulching type on furrows are given, detailed definition of the factors are possible. The approach was developed from field survey in South-Korea, it is expected to be used for potential soil loss using USLE in South-Korea.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.2
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• pp.76-82
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• 2006

This paper investigates the magnetic field behavior and its iron losses in the stator core using electrical steels. The analysis model is a brushless motor with the permanent magnet. The elliptical rotating and alternating flux distributions with non-sinusoidal waveform are obtained by Finite Element Method and then their harmonic components are extracted. Based on these results, the local iron losses in the stator core caused by the harmonic flux are calculated. And then this paper explains the relation between flux waveform and iron loss produced in each part of the stator core. Furthermore, the iron loss at no load condition is measured and compared with the analysis results.

• Progress in Superconductivity and Cryogenics
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• v.6 no.2
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• pp.1-6
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• 2004

It is important to estimate the total AC loss which is the total energy, or power, dissipated in the superconductor in the simultaneous application of AC transport current and an AC external magnetic field. Experimental and numerical works on AC loss estimation of high $T_c$ superconductors in the author's group are reviewed. The method and the set-up for total AC loss measurements are described. The experimental results for a twisted Bi-2223 multifilamentary tape and a Y-123 mm conductor are given. A general theory for numerical electromagnetic field analysis of superconductor by the finite element method is explained. The numerical results for twisted Bi-2223 multifilamentary tapes and a rectangular superconductor simulating coated conductors are presented.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.291-293
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• 1997

The external magnetic field which is applied to the superconducting wire generates coupling loss. Analytical method has been used for the calculation of the coupling loss. This paper calculates the coupling loss that is generated in the matrix by the external magnetic field. Two-dimensional Finite Element Method has been used for the calculation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.726-731
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• 2002

The purpose of this paper is to analyze the path loss for the mobile cellular system. The maximum distance is 150 km and the area is about 6,000 $\textrm{km}^2$ and the field test was performed for the total 5 base stations. The path loss was calculated by Hata and Okumura models, respectively. As a result, it was shown that a proper model for the field test data is the middle one between the rural model and suburban/rural Hata model.