• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.1 s.24
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• pp.109-116
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• 2006

This paper presents a real time distance measuring device using a W-band linear frequency modulated continuous wave(FMCW) radar and TMS320C6701 digital signal processor(DSP). We used FFT operation for measuring distance with the beat signals and the results of FFT could be converted to distance with ease. We presented how to implement a real time miniaturized hardware system including network protocols using a single DSP core. Also how to control the modulation signal of FMCW system to compensate the VCO nonlinearity using the Time Gating control of DSP is presented. We have shown that the proposed system has good performances for measuring distance in real time via outdoor environment experiments.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.191-192
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• 2007

This paper presents a 900MHz fractional-N frequency synthesizer for radio frequency identification (RFID) reader using $0.18{\mu}m$ standard CMOS process. The IC meets the EPC Class-1 Generation-2 and ISO-18000 Type-C standards. To minimize VCO pulling, the 900MHz VCO is generated by a 1.8GHz VCO followed by a frequency divider. The settling time of the synthesizer is less than $20{\mu}m$. The frequency synthesizer achieves the phase noise of -105.6dBc/Hz at 200kHz offset. The frequency synthesizer occupies an area of $1.8{\times}0.99mm^2$, and dissipates 8mA from a low supply voltage of 1.8V.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.10 s.89
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• pp.938-943
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• 2004

In this paper, we propose a T-shaped DGS for CPW and provide the closed-form solutions for power loss rate, and bandwidth of the DGS. The proposed T-shaped DGS structure has a range of capacitance(C) 5.5 times wider than the dumbbell-shaped DGS structure. In addition we also analyze relations between R, L, C values of the DGS equivalent circuit and total loss rate, BW, $\omega_0$ of the DGS.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.9C
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• pp.913-921
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• 2005

A complex bandpass sampling technique can provide a more flexible architecture for designing a software- defined radio(SDR) system, because it has several advantageous features of larger sampling range and lower minimum sampling frequency than a real bandpass sampling method. In spite of the potential advantages of the complex bandpass sampling, solid investigation for the direct downconversion of multiple signals by the complex sampling theory has not been reported yet. Thus, we propose in this paper a novel scheme for the downconversion of multiple signals using the complex bandpass sampling, and develop the formulae related to the complex bandpass sampling for practical usage, such as the valid sampling range, the intermediate frequency (If), and the minimum sampling frequency of the downconversion of multiple RE signals. Such derived formulae are verified from simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3C
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• pp.256-268
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• 2007

In this paper, we present a watermarking method for 3-D mesh sequences. The main idea is to transform vertex norm with the identical connectivity index along temporal axis using wavelet transform and modify the distribution of wavelet coefficients in temporally high (or middle) frequency frames according to watermark bit to be embedded. All vertices are divided into groups, namely bin, using the distribution of coefficients in low frequency frames. As the vertices with the identical connectivity index over whole frames belong to one bin, their wavelet coefficients are also assigned into the same bin. Then, the watermark is embedded into the wavelet coefficients of vertex norm. Due to the use of the distribution, our method can retrieve the hidden watermark without any information about original mesh sequences in the process of watermark detection. Through simulations, we show that the proposed is flirty robust against various attacks that are probably concerned in copyright protection of 3-D mesh sequences.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12C
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• pp.1248-1255
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• 2005

We investigate the OFDM-based wireless LAN systems operating in the 60 GHz frequency band as part of the fourth-generation (4G) systems. The 60 GHz band is of much interest since this is the band in which a massive amount of spectral space has been allocated worldwide for dense wireless local communications. This paper gives an overview of 60 GHz bandchannel characteristics and an effect on phase noise. The performance of OFDM system is severely degraded by the local oscillator phase noise, which causes both common phase error and inter-carrier interference. In this paper, we apply phase noise suppression (PNS) algorithm that is easy for implementation to OFDM based 60 GHz wireless LAM system and analyze the SER performance. In case of using the PNS algorithm, SER performance is improved about 6dB, 7.5dB, respectively in 16, 64-QAM.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.3
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• pp.380-388
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• 2011

In this paper, we developed the X-band 63 watt pulsed SSPA(Solid State Power Amplifier) by using HMIC(Hybrid Microwave Integrated Circuits). The pulsed SSPA consists of power supply and 3-stage amplifier modules : pre-amplifier stage, driver-amplifier stage, final-amplifier stage. The developed pulsed SSPA provides more than 63 watts of output power with a short pulse width and the duty cycle of up to 1.2 % at $70^{\circ}C$. The fabricated module offers great than 37 dB of saturated gain across the operating band. Input and output VSWR is <1.5:1. This module has an average current of 400 mA typical and operates at a +28 $V_{dc}$ supply. The developed SSPA in this paper can apply to pulsed Doppler radar with high speed operation.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.323-326
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• 1998

A LNA(Low Nosise Amplifer) module for the Ka-band satellite transponder has been developed, which is composed of developed two MMIC chips and 50$\Omega$ line. This LNA exhibited noise figure less than 3.12dB, linear gain higher than 32dB from 30.085GHz to 30.885GHz frequency range. Temperature test from $20^{\circ}to$ $60^{\circ}C$ of the LNA Module showed very small noise figure and linear gain variation of 0.2 dB and 0.4dB.

• Defense and Technology
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• no.4 s.254
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• pp.54-65
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• 2000

셀룰라망을 이용한 위치보고체계는 전파통달거리를 고려한 셀 단위로 구축하였기 때문에 지휘망을 이용하는 방안에 비해 신뢰성 있는 보고를 기대할 수 있으며, 동일한 정보를 1, 2차 상급부대에 중복 보고할 필요가 없고, 일정거리 이상의 다른 셀에서 같은 대역의 주파수를 사용해도 무방하므로 주파수 재사용의 효과도 거둘 수 있다. 아울러 인터넷과 데이터 베이스 관리 시스템을 소프트웨어로 효과적으로 연동시킴으로써 현재 상용에서 각광 받고 있는 Web-Server 개념을 군 무선 데이터 통신에 도입하고 하드웨어도 대용량의 지능망으로 발전한다면 위치보고 뿐만 아니라 늘어나는 정보를 효과적으로 처리하기에 충분하리라 판단된다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04a
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• pp.437-439
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• 2003

본 논문에서는 대역확산방식을 응용한 새로운 워터마킹 방법에 대해서 설명하고, 이를 이용하여 semi-fingerprinting을 구현할 수 있는 데이터 구조에 대해서 기술하였다. 본 논문은 저작권 보호에 주초점이 맞추어져 있는 워터마크 기술을 실질적으로 필요한 fingerprinting분야에 적용함으로써, 그 동안 학문연구에 그치고 있었던 워터마크 기술을 산업적 응용에까지 확대시키는데 큰 기여를 할 것으로 기대된다. 본 논문에서 제안한 워터마킹 방법은 난수이동(random number shift)방법을 이용하여 데이터 삽입량을 증가시켰다. 또한, semi-fingerprinting에 적용하기 위해 일본 내에서 진행중인 cIDf의 지침에 기반 하여 워터마크를 구성하였다.