• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.1
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• pp.80-93
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• 2007

This paper suggests structures of the Object Descriptor and the Elementary Stream Descriptor that provide multi-view video services in 3-Dimensional Audio Video technical standards of current MPEG-4. First, it defines that the structures of the Object Descriptor and the Elementary Stream Descriptor on established MPEG-4 system, then distributes individually, and analyzes that. But extension of established system is inappropriate for providing multi-view audio video services connected transmissions and receptions. And, this paper suggests a structure of new Object Descriptor able to switch viewpoints that considers the correlation between each viewpoints, when multi-view video is transmitted. By means of that, it is able to switch viewpoints according to a requirement of a user in a multi-view video services, and reduce overheads for transmitting information about necessary viewpoint.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.4
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• pp.30-37
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• 2014

The Electronic Toll Collection System based on Free-Flow Multi-Lane is needed to solve some yearly problems such as traffic congestion, safety accident, maintenance by hold-up of one way hi-pass system. The hi-pass communication system is first-in, first-out method in one way environment so, it can't handle various running patterns such as vehicle platoon, switching lane and passing in multi-lane environment. In this thesis we compared and analyzed the communication system of foreign countries ETCS operating system and domestic hi-pass communication system, then studied communication system which can run in multiple-way accepting existing hi-pass OBU. And we formed the communication system of Free-Flow Multi-Lane environment as a plan using incoherent of IR antenna and coherent of RF antenna. The communication system in Free-Flow Multi-Lane environment can be used not alone in parking garages but in expressways of ETCS and toll roads from now on.

• Journal of Power Electronics
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• v.14 no.2
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• pp.271-281
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• 2014

Fluctuating wind conditions necessitate the use of a variable speed wind turbine (VSWT) with a AC/DC/AC converter scheme in order to harvest the maximum power from the wind and to decouple the synchronous generator voltage and frequency from the grid voltage and frequency. In this paper, a combination of a three phase diode bridge rectifier (DBR) and a modified topology of the diode clamped multilevel inverter (DCMLI) has been considered as an AC/DC/AC converter. A control strategy has been proposed for the DCMLI to achieve the objective of grid interface of a wind power system together with local load compensation. A novel fixed frequency current control method is proposed for the DCMLI based on the level shifted multi carrier PWM for achieving the required control objectives with equal and uniform switching frequency operation for better control and thermal management with the modified DCMLI. The condition of the controller gain is derived to ensure the operation of the DCMLI at the fixed frequency of the carrier. The converter current injected into the distribution grid is controlled in accordance with the wind power availability. In addition, load compensation is performed as an added facility in order to free the source currents being fed from the grid of harmonic distortion, unbalance and a low power factor even though the load may be unbalanced, non-linear and of a poor power factor. The results are validated using PSCAD/EMTDC simulation studies.

• Journal of KIISE:Information Networking
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• v.27 no.2
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• pp.219-225
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• 2000

In order to provide a proper mobile internet service, Mobile IP is necessary to support IP mobility. Service network should be a backbone network among mobile agents which support mobility, and MPLS(Multi-protocol Label Switching) of IETF(Internet Engineering Task Force) is being considered as a backbone network because of its speed, scalability and the excellent service capability. MPLS, however, doesn't provide a way to support the mobility of the nodes. In this paper, we present an efficient IMT-2000 network architecture using MPLS to handle Mobile IP. The proposed architecture combines the MPLS label distribution and Mobile IP registration. It doesn't use the layer 3 encapsulation, instead it uses layer 2 for tunneling the data, reduces the size of the header, and it can tunnel the data without delay, which is needed to look up the mobility binding list, as a result.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.4 s.334
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• pp.15-20
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• 2005

Multi-Input, Multi-Output system suffers for the spatial channel correlation due to lack of spatial diversity. To overcome this defect, the antenna selection and switching system is proposed which selects the adequate antenna subset with highest channel diversity gain and switches the trasmission techniques according to channel environments. However. its performance analysis is insufficient due to the difficulty of modeling the spatial channel correlation. In this paper, the theoretical upper bound of symbol error probability is derived by using the statistical properties of Frobenius norm and minimum eigen-value of channel matrix. By computer simulation, it is shown that the derived theoretical upper bound is similar to the simulation results.

• JSTS:Journal of Semiconductor Technology and Science
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• v.6 no.1
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• pp.52-58
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• 2006

Single-electron transistor (SET)-based logic cells and SET/FET hybrid integrated circuits have been fabricated on SOI chips. The input-output voltage transfer characteristic of the SET-based complementary logic cell shows an inverting behavior where the output voltage gain is estimated to be about 1.2 at 4.2K. The SET/FET output driver, consisting of one SET and three FETs, yields a high voltage gain of 13 and power amplification with a wide-range output window for driving next circuit. Finally, the SET/FET literal gate for a multi-valued logic cell, comprising of an SET, an FET and a constant-current load, displays a periodic voltage output of high/low level multiple switching with a swing as high as 200mV. The multiple switching functionality of all the fabricated logic circuits could be enhanced by utilizing a side gate incorporated to each SET component to enable the phase control of Coulomb oscillations, which is one of the unique characteristics of the SET-based logic circuits.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.54-57
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• 2007

Much researches have studied for seamless mobility service. Those focused on minimizing the delay time due to the handover. In this paper, we suggest seamless mobility service with the network-based preemptive operations. With these operations, if it's found that the MT(Mobile Terminal)'s handover using L2-trigger event, old access network buffers the delivering data. Therefore this can decrease the data drop rates. And also, this can deal with the ping-pong's phenomenon of MT. At the end of MT's movement, these operations can provide seamless mobility service sending buffered data after checking the MT's movement. This mechanism uses MPLS-LSP(MultiProtocol Label Switching-Label Switched Path) in core network for fast process.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.2
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• pp.19-25
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• 2008

When there are numerous wireless communication systems co-existing in the limited available frequency resource, an unexpected time delay can be caused during the system switching. So, in order to reduce this time delay, a mode selection method is required. In this paper, we propose a mode selection method to minimize the time delay for multi-system wireless communication systems. For the sake of efficiency, the mode selection method is designed by analyzing the preamble characteristics of different standards. Instead of performing a full search, we propose the preamble partial search to reduce the time delay to a minimum. Simulated with Matlab in an additive white Gaussian noise(AWGN) environment with a signal to noise ratio(SNR) of 10dB and bit error rate(BER) of $10^{-6}$, we evaluated and showed the performance improvement gained by using our proposed mode selection method.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.5
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• pp.343-354
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• 2009

In this paper, a magnetic-less dc-dc switching converter realizing an integrable power conversion system is described. Instead of magnetic devices, the inductive impedance range of piezoelectric transducers is utilized to store and resonate the energy for soft-switching. Piezoelectric devices have no windings and deliver the power by the electrodes, which lead to mass product through semiconductor-manufacturing process. This paper presents a resonant-type step-up dc-dc power converter employing a disk-type piezoelectric transducer, analyzing the operation principles and the frequency control characteristics. Also, a topology extension of the single stage converter into cascaded multi-stage is presented and analyzed with the operation principles and control characteristics. For verification of the analysis, a 10W output dc-dc power converter hardware was implemented. The hardware experiments shows a good frequency control and power efficiency greater than 96% in the single stage. A hardware prototype of the extended multi-stage one was also realized and tested. The results shows that the converter has the same frequency control performance and high efficiency such as 93%.

• Journal of Powder Materials
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• v.27 no.4
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• pp.333-338
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• 2020

In this study, we fabricate a thin- and dense-BCuP-5 coating layer, one of the switching device multilayers, through a plasma spray process. In addition, the microstructure and macroscopic properties of the coating layer, such as hardness and bond strength, are investigated. Both the initial powder feedstock and plasma-sprayed BCuP-5 coating layer show the main Cu phase, Cu-Ag-Cu₃P ternary phases, and Ag phase. This means that microstructural degradation does not occur during plasma spraying. The Vickers hardness of the coating layer was measured as 117.0 HV, indicating that the fine distribution of the three phases enables the excellent mechanical properties of the plasma-sprayed BCuP-5 coating layer. The pull-off strength of the plasma-sprayed BCuP-5 coating layer is measured as 16.5 kg/㎠. Based on the above findings, the applicability of plasma spray for the fabrication process of low-cost multi-layered electronic contact materials is discussed and suggested.