• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04a
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• pp.83-87
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• 2002

In order to improve the capability of magnetic circuit, magnetic materials are used for all kinds of electromagnetic energy-conversion devices. This paper presents the analysis method considering magnetic properties of the magnetic material and analyzes that the effects of magnetic materials. In addition, it is described that the requirements of magnetic materials for the improvement of electric machines. Several application examples using a metal powder in electromagnetic energy conversion devices is introduced.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.329-334
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• 2005

As more high power wide band gap devices are being utilized. the thermal management issues associated with these devices need to be resolved. High power small devices dissipate excessive heat that must be cooled, but traditional cooling methods are insufficient to provide such a cooling means. This paper will evaluate a micro-capillary pumped loop thermal management system that is incorporated into the shim of the device, taking advantage of phase-change to increase the thermal conductivity of the system. The results of the modeling of the thermal management system will be discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 2008.08a
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• pp.144-145
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• 2008

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.2
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• pp.337-344
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• 2017

The ICT industry is changing. From the PC to mobile devices, and from the mobile devices to wearable and IoT devices, it is changing. It requires the OS for the IoT, coming out various IoT OS have been developed in accordance with this need. In this paper, we discuss the kind of OS that supports IoT device, analyze the technology trends.

• Journal of electromagnetic engineering and science
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• v.14 no.4
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• pp.353-359
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• 2014

Recently, the use of mobile devices has increased, and mobile traffic is growing rapidly. In order to deal with such massive traffic, cognitive radio (CR) is applied to efficiently use limited-spectrum resources. However, there can be multiple communication systems trying to access the white space (unused spectrum), and inevitable interference may occur to cause mutual performance degradation. Therefore, understanding the effects of interference in CR-based systems is crucial to meaningful operations of these systems. In this paper, we consider a long-term evolution (LTE) system using additional spectra by accessing the TV white space, where low-power devices (LPDs) are licensed primary users, in addition to TV broadcasting service providers. We model such a heterogeneous system to analyze the co-existence problem and evaluate the interference effects of LPDs on LTE user equipment (UE) throughput. We then present methods to mitigate the interference effects of LPDs by 'de-selecting' some of the UEs to effectively increase the overall sector throughput of the CR-based LTE system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.10a
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• pp.95-97
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• 1988

The instability of MOS devices is mainly caused by the oxide charges, and as the need to develop the gate metal grows researches for various new metal gate have been performed, and in these researches, the difference work function existing between the metal and the semiconductor should be considered. Here int his paper, the device is made by the sputtering and the LPCVD method using pure Al, compound metal. poly-si, as a gate metal, the result of the research was shown that the work function difference from using different gate metals effects on the flatband voltage shift. This means we can infer that the threshold voltage adjustment is possible by using different gate metals and this whole mechanism makes the devices behavior more stable.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.7
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• pp.565-570
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• 1998

Recently a few MJ superconducting magnetic energy storage ($\mu$ SMES) devices become commerci-ally available as one of the energy storage devices for uniterruptible power supply (UPS) systems. For such a ($\mu$ SMES) devics, a few kA class superconducting cables with high current density, high stability and excellent pulse characteristics are required. To acquire data for the superconduction cables related to design and fabrication of a 0.7 MJ $\mu$ SMES device, we tested critical currents and quench characteristics for several winding tensions and various remping rates especially. It is shown from the results that winding tensions have much influence on quench currents of the $\mu$ SMES devices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05a
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• pp.50-54
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• 2003

The output characteristics of thin film NiO/NiFe bilayered magnetoresistive device have been measured as a function of the direction of external magnetic field. Each layer was fabricated by rf magnetron sputtering method, and especially, the under layer, NiO, was fabricated under the in-situmagnetic field of about 1000Oe. The magnetoresistive devices were designed with the angle of 45degree between the direction of current of the device pattern and the induces magnetic field in the NiO film layer. The output of the devices had a good linearity when the devices were placed on the external magnetic field perpendicular to induced field direction and also 45 degree with the currenr path direction.

• International journal of advanced smart convergence
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• v.4 no.2
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• pp.1-5
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• 2015

The necessity to distribute energy wirelessly has been spurred by the tremendous growth in the use of portable devices. Mobile devices have become ubiquitous and the circuits within them have been optimized to consume extremely low amounts of power. Such portable electronic sets are in constant use and the frequent need to recharge them; using conventional wired mechanisms have hindered the mobility of users. Wireless transmission of energy to power-up devices has been proposed since the days of Tesla and since then many theories and methods have been invented. This paper discusses some of those techniques briefly.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.11
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• pp.898-903
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• 2001

In this study, we investigated amounts, distributions and sizes of pores of multilayer piezoelectric transformer, and predicted heat emission property and electrical characteristics according to designs of internal electrode. Forming densities of device having MLC, fingered and full filled internal electrode structure were 4.73 g/㎤, 4.80 g/㎤, 4.82 g/㎤ and forming porosities were 17.3737%, 13.1475%, 12.6121%, respectively. And sintered densities of MLC structured, fingered and full filled devices were 7.76 g/㎤, 7.75 g/㎤, 7.84 g/㎤ and sintered porosities were 4.0967%, 2.7132%, 2.5317%, respectively. Therefore, we concluded that fingered and full fi1led internal electrode devices, expecially, fingered internal electrode devices had cost-effective effect and maximum poling effect due to higher sintered density and lower porosity than MLC structured device. Also we can predict that they have an effect on good heat emission and high output properties of multilayer piezoelectric transformer.