• Journal of information and communication convergence engineering
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• v.4 no.4
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• pp.136-140
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• 2006

In this paper, we consider the detection of orthogonal space-time block codes (OSTBCs) without channel state information (CSI) at the receiver. Based on the conventional blind cyclic decoder, we propose an enhanced blind cyclic decoder which has higher system performance than the conventional one. Furthermore, the proposed decoder offers low complexity since it does not require the computation of singular value decomposition.

• Journal of information and communication convergence engineering
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• v.5 no.2
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• pp.109-111
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• 2007

In this paper, MOS devices with ultrathin gate dielectrics (5.5 nm) are characterized and compared with those with conventional oxides particularly for nanoscale CMOS applications. Nitrogen concentrations and profiles in the nitride gate dielectrics were obtained that will play an important role in improving both hot-carrier lifetime and resistance to boron penetration. This approach seems very useful for future nanoscale CMOS device applications.

• Journal of information and communication convergence engineering
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• v.4 no.1
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• pp.10-12
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• 2006

In this paper, we present a method to evaluate the BER performance of a coherent QPSK system using an adaptive array to eliminate CCI and demonstrate closed-form expressions for obtaining exact BER of the desired user for the case in which the time delays of all users are equal. The theoretical results are verified by computer simulation under the assumption that Least Mean Square beamforming algorithm is employed.

• Journal of information and communication convergence engineering
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• v.4 no.3
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• pp.108-110
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• 2006

Film bulk acoustic resonators for radio frequency wireless applications are presented. Various simulations and modeling were carried out. The impedance of a five-layered FBAR showed almost the same trend of the wideband characteristics as that of an ideal FBAR, but the characteristics of the higher modes appear to be much more suppressed. In addition, the wideband impedance decreased with increasing device size. The resonance characteristics depend strongly on the physical dimensions.

• Journal of information and communication convergence engineering
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• v.4 no.3
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• pp.111-113
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• 2006

A new thin film deposition technique of piezoelectric ZnO film and its successful application for film bulk: acoustic resonator (FBAR) devices are presented. The two-step deposition used seems to be able to deposit ZnO film with a highly preferred orientation. The FBAR devices with the ZnO films show an excellent return loss of $35{\sim}50$ dB at $1.5{\sim}2$ GHz.

• Journal of information and communication convergence engineering
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• v.4 no.4
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• pp.155-157
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• 2006

This paper presents the thermal technique to improve characteristic of planar spiral inductors. The spiral inductors were fabricated on silicon dioxide/silicon (SiO2/Si) wafer. The thermal treatment was done by annealing processes. The measure results showed a considerable improvement of return loss (Sl1). This thermal treatment seems very promising for enhancing spiral inductors based RF IC's.

• Journal of information and communication convergence engineering
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• v.4 no.4
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• pp.151-154
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• 2006

In this work, a novel optimal multiuser detection (MUD) approach, which not only achieves the optimal maximum-likelihood (ML)-like performance but also has reasonably low computational complexity, for Space-time coded OFDM (ST-OFDM) systems is presented. In the proposed detection scheme, the signal model is firstly re-expressed into linearly equivalent one. Then, with the linearly equivalent signal model, a new jointly MUD algorithm is proposed to detect signals. The ML-like bit-error-rate (BER) performance and reasonably low complexity of the proposed detection are verified by computer simulations.

• Journal of information and communication convergence engineering
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• v.4 no.2
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• pp.88-91
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• 2006

In this paper, a novel physical structure for planar spiral inductors is proposed. The spiral inductors were designed and fabricated on multi-layered substrate Bragg-reflector/silicon (BR/Si) wafer. The impacts of multi-layered structure substrate and pattern on characteristics of inductor were studied. Experimental results show that the inductor embedded on Bragg reflector/silicon substrate can achieve the best improvement. At 0.4-1.6 GHz, the Bragg reflector seems to significantly increase the S11-parameter of the inductor.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.196-199
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• 2007

In this paper, we studied a ZnO-based film bulk acoustic wave resonator (FBAR) device fabricated on top of a novel multi-layered Bragg reflector with chromium adhesion layers $(0.03{\mu}m-thick)$ inserted. The performance of FBAR device could be significantly improved using proper thermal treatments. At ${\sim}2.75$ GHz, we could achieve good return loss and quality factor (Q). This device fabrication technique will be useful for the future mobile WiMAX applications.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.211-214
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• 2007

In this paper, the resonance characteristics of ZnO-based film bulk acoustic resonator (FBAR) devices with thick bottom electrode are investigated. The ultra-thin Cr film (300 ${\AA}-thick$) between $SiO_2$ film and W film is formed by a sputtering-deposition in order to enhance the adherence at their interfaces. The resonance frequency of three different resonator devices was observed to be ${\sim}2.7$ GHz, and the resonance characteristics $(S_{11})$ of the FBAR devices were found to have a strong dependence on the thickness of bottom electrode.