• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.11
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• pp.61-68
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• 2008

In this paper, we propose a RF front-end developments for vehicle UWB radar systems. UWB systems have a very narrow pulse width that is below 1ns. Therefore, UWB is designed to have broadband quality of low power several GHz and must coexist with the radio communication system. UWB's advantages include high channel capacity and data rate, because precise resolution for multi-path can easily position estimate and Rake receiver. Also, UWB has low interference because it displays broadband quality of low power. Positioning is made possible by short range accuracy, which can reduce the expense of system design. An RF front-end module is designed using the DCR(Direct ConveRsion) method and is composed in RF for vehicles at a low-cost.

• The Journal of the Acoustical Society of Korea
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• v.36 no.2
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• pp.130-135
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• 2017

In this paper, we propose an interface for interactive sound experience in the virtual concert hall. The proposed interface consists of two systems, called 'virtual acoustic position' and 'virtual active listening'. To provide these systems, we applied an artificial reverberation algorithm, multi-channel source separation and head-related transfer function. The proposed interface was implemented by using Unity. The interface provides the virtual concert hall to user through Oculus Rift, one of the virtual reality headsets. Moreover, we used Leap Motion as a control device to allow a user experience the system with free-hand. And user can experience the sound of the system through headphones.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.7A
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• pp.682-687
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• 2010

The IEEE 802.15.4a specification targets the low-rate (LR) Impulse-radio (IR) ultra-wideband (UWB) system which is now widely applied in the WPANs considering rather short distance communications with low complexity and power consumption. The physical (PHY) layer uses concatenated coding with mixed binary phase-shift keying and binary pulse-position modulation (BPSK-BPPM), and direct sequence spreading with time hopping in order that both coherent and non-coherent receiver architectures are supported. In this paper, the performances of multiple access schemes compliant with IEEE 802.15.4a specification are investigated with energy detection receiver, which allow avoiding the complex channel estimation needed by a coherent receiver. However, the performance of energy detection receiver is severely degraded by multi-user interference (MUI), which largely diminishes one of the most fascinating advantages of UWB, namely robustness to MUI as well as the possibility to allow parallel transmissions. So as to improve the performance of multiple access schemes, we propose to apply the novel TH sequences as well as to increase the number of TH positions. The simulation results show that our novel multiple access schemes significantly improve the performance against MUI.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.65.2-65.2
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• 2010

We present a result of $^{13}CO$(1-0) survey toward the Outer Galactic Plane using the multi-beam receiver system recently installed on the 14 m telescope at Taeduk Radio Astronomy Observatory(TRAO). Our first target region is from $l=108^{\circ}$ to $113^{\circ}$ and $b=-1^{\circ}$ to $+1^{\circ}$, and some extended regions are included where emission is still arising. All data are on 50" grid. Velocity resolution is 0.63 km/sec, and the total velocity range is from -150 km/sec to 100 km/sec. A total of 40,000 spectra were obtained. The rms noise is about 0.2 K per channel for unsmoothed raw data. We will present a few initial results of the survey database.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.57-61
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• 2006

As high speed internet users are tremendously increasing, three are keenly in need of development of high speed portable internet technology which can provide high quality wireless internet service cheaply even in the mobile. Unlike the FDD-CDMA, TDD-OFDMA has relatively poor wave environment with inducing interference, fading and delay because it agrees to multi-carrier modulation method and time-division radio telecommunication system. To solve this problem, it is necessary to develop repeater operating by digital signal processing method which have more strict wireless channel control and wave signal processing technology over TDD telecommunication equipments. This thesis is dealing with design and implementation of Digital RF Repeater which implemented 'Synchronization Acquisition Unit', 'TDD signal switching Unit', 'Feedback Signal Cancellation Unit'. Over this argument, we will develop digital RF repeater with more cheap, more adaptive in wave environment like oscillation control, adaptive wave monitoring and output increasing and having control function as a result it will be helpful for success in high speed portable internet service business.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.7A
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• pp.528-534
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• 2012

In order to achieve high capacity and reliable link quality of the overlay convergent networks with the cognitive networking based on the advanced capability of the mobile terminal, a Distributed Wireless Communication System (DWCS) can provide the capability of enhancing the link quality. This paper has considered virtual cell: the Dual Virtual Cell (DVC), and also proposes DVC employment strategy based on radio resource monitering. The considered system constructs DVC for multi-user high-rate data transmission, and the DWCS system exploits space-time trellis codes i.e., STTC to improve a spectral efficiency. The effects of imperfect CSI(channel state information) on the system performance has also been investigated.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.4
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• pp.37-46
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• 1996

In this paper, we analyzed the performance improvement of the DS-CDMA/dPSK cellular mobile communication system with CCI canceller and RAKE receiver techniques in mobile radio channel which is characterized by AWGN, Multi-user interference (mUI) and frequency-selective rayleigh fading. System capacity i.e., number of user per cell has been derived and the evaluated results are shown in figuraes as a function of PN code sequence length, number of RAKE receiver tap, BER and E$_{b}$/N$_{o}$. The voice activity factor is assumed to be 3/8 the number of sectors in a cell 3 and MUI is modeled as gaussian process. From the results, the capacity of the DS-CDMA/DPSK cellular mobile communication system is improved by adopting CCI canceller. When we adopt the RAKE receiver to mitigate the multipath fading, the error performance is improved and the amount of improvement is proportional ot the number of taps L in the case that each tap contains a signal component and the better of improvement can be obtained, the smaller of the SNR difference in each tap. The system capacity is more increased when the CCI canceller and the RAKE receiver is used in cascade.

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.4
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• pp.295-301
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• 2011

A triple-band transceiver module for 2.3/2.5/3.5 GHz mobile WiMAX, IEEE 802.16e, applications is introduced. The suggested transceiver module consists of RFIC, reconfigurable/multi-resonance MIMO antenna, embedded PCB, mobile WiMAX base band, memory and channel selection front-end module. The RFIC is fabricated in $0.13{\mu}m$ RF CMOS process and has 3.5 dB noise figure(NF) of receiver and 1 dBm maximum power of transmitter with 68-pin QFN package, $8{\times}8\;mm^2$ area. The area reduction of transceiver module is achieved by using embedded PCB which decreases area by 9% of the area of transceiver module with normal PCB. The developed triple-band mobile WiMAX transceiver module is tested by performing radio conformance test(RCT) and measuring carrier to interference plus noise ratio (CINR) and received signal strength indication (RSSI) in each 2.3/2.5/3.5 GHz frequency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.12
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• pp.1065-1075
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• 2012

For the purpose of providing high data rate real-time services, radio transmission technologies (RTT) for ship ad-hoc network (SANET) based on the Recommendation ITU-R 1842-1 are designed. Physical layer parameters of SANET are contrived to meet the requirements of the specification. In order to improve the link reliability for SANET, in this paper, we investigate the performance of the SANET with the multiple antennas, where receive combining (RC), transmit diversity (TD), and beamforming (BF) are employed, respectively. Based on the analysis of the packet error rate (PER) under the highly correlated maritime wireless channel model, we select the efficient multiple antenna schemes for SANET to improve the link reliability. In addition, the optimal MCS levels for the single-carrier (SC) SANET with the bandwidth of 25 kHz, and the multi-carrier (MC) SANET with the bandwidth of 50 kHz and 100 kHz are finalized.

• Journal of Biomedical Engineering Research
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• v.29 no.3
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• pp.191-197
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• 2008

This research focused on the development of wireless telemetry system that can monitor heart rates of multiple rehabilitation patients in real time without constraint. The whole system consists of the multiple patient's side devices (PSDs) and one central monitoring system (CMS). The PSD consists of a microphone, amplifier, filter, microcontroller, and RF (Radio Frequency) modem. In addition, the PSD was designed to be wearable and low power consumption. The CMS consists of an RF modem and general PC and it was designed to monitor heart rates from multiple patients simultaneously. The system warns an alarm signal when a patient's heart rate exceeds the pre-set range for each patient. This system can be useful to monitor the heart rate of exercising rehabilitation patients and control the patients condition and the exercising level.