• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.7 s.110
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• pp.665-672
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• 2006

In this paper, we propose and fabricate the dual-band microstrip patch antenna with parasitic patch for S-DMB(Satellite-Digital Multimedia Broadcasting) and ITS (Intelligent Transport System) services. The measured - 10 dB bandwidth and the minimum return loss is 300 MHz and - 27 dB for S-DMB, 600 MHz and -17 dB for ITS, respectively. It is noticed that the measured and simulated results are agreed well. The S-DMB antenna has conical beam pattern in the vertical plane and has omni-directional beam pattern in the horizontal plane. The conical beam pattern has the maximum gain about 4.2 dBi when ${\theta}$ is $45^{\circ}$ at the center frequency of 2.6 GHz. The ITS antenna has directional beam pattern in the vertical plane that has maximum gain about 6.4 dBi when ${\theta}$ is $0^{\circ}$ at the center frequency of 5.8 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.10
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• pp.1040-1047
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• 2002

In this paper, we investigated noise decoupling on the power bus by the screw connection, used to the mechanical join and grounding of the PCB ground to chassis. The screw connection penetrates the power bus and then it affects noise propagation on the power bus. To verify effect of the screw connection, we compare bare board with board having screws connection with 0.5 mm separation between power bus and chassis. From these results, we observed that the power bus noise was decreased about 5 dB at the frequency range from 0.1 GHz to 1 GHz. Also, we verified that a 4-layer PCB with signal trace had the better signal quality up to 600 MHz by the screw connection. Therefore, these results will be useful in designing to the high speed circuit and chassis.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.2
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• pp.177-184
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• 2003

A series of experimental work has been conducted to evaluate the capability of Ground Penetrating Radar (GPR) system in detecting delamination inside concrete. Three antenna at 900 MHz, 1000 MHz, and 1500 MHz frequency are used in the experiments for laboratory size specimens, and 400 MHz antenna has been used for a large size specimen. The laboratory size specimens have the dimensions of 1,000 mm (length) ${\times}$ 600 mm (width) ${\times}$ 140 mm (thickness) with a delamination of 200 mm (length) ${\times}$ 600 mm (width) ${\times}$ 140 mm (thickness). The cover depth of the delamination is varied as follows: 20 mm, 30 mm, 60 mm, and 70 mm. In all cases, the delamination has been successfully identified. The property of three frequencies was seized about detecting delamination. Also, it was shown that the image results in GPR were improved by signal processing.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.8
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• pp.9-16
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• 2000

MOS transistors are fabricated and evaluated for RF IC applications such as mobile communication systems using 0.35m CMOS process. Characteristics of MOSFETs are analyzed at various channel length, width and bias conditions. From the analysis, cut-off frequency ($f_T$) is independent on channel width but maximum oscillation frequency ($f_{max}$) tends to derease as the channel width increases. As channel length increases, $f_T$ and fmax decrease. $f_T$ is 22GHz and fmax is 28GHz at its maximum value. High frequency noise performance is improved with larger channel width and smaller channel length at same bias conditions. NFmin at 2GHz is 0.45dB as a minimum value. From the evaluation, MOSFETs designed using 0.35m CMOS process demonstrated a full potential for the commercial RF ICs for mobile communication systems near 2GHz. And optimization methods of the CMOS transistors for RF applications are presented in this paper.

• Journal of The Korean Association of Information Education
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• v.22 no.5
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• pp.605-611
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• 2018

On-Line Lectures are becoming more common due to the MOOK service and the expansion of national policy in Korea. Especially, It is being changed to new remote mixed style from traditional lecture in universities. We propose and implement a remote contents making tool with audio synchronization function based on more with less resources. To implement our proposed algorithm, we design an interactive interface to assign multiple cutting intervals and convert an input video to print a new result. In experimental, we can confirm our algorithm works properly with average performance value 9.3% cpu share ratio and 87mega byte ram usage(CPU 2.60GHz, 820*600 Area).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.6
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• pp.1153-1157
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• 2004

This paper describes a new programmable DLL_based frequency synthesizer. Generally, PLLs have been used for frequency synthesis. Inherent fast locking DLLs are also used for frequency synthesis. However, DLL needs a frequency multiplier for various frequencies. A conventional frequency multiplier used in DLL has a restriction in which a multiple is fixed. However, the proposed DLL can generate clocks which are from 6 times to 10 times of the reference clock. Frequency range of the proposed DLL is from 600MHz to 1GHz. The idea has been confirmed by HSPICE simulations in a $0.35-\mu\textrm{m}$ CMOS process.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.139-142
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• 2009

Rapid developments in the field of electronic communication have given people's daily life much more convenience and abundance. However, making precise electrical and electronic devices and control systems lighter, smaller, and faster have caused lots of problems such as interference of external electric source, malfunction brought by electric fast transient(EFT), and influence on human body. In this research, the EMC filter in the high powered breaker was designed and fabricated as a countermeasure. The filter attenuated noise more than 30 ~ 75 dB in the range of 10 MHz ~ 1.5 GHz. And, when the EFT of 4 kV in the level 4 of IEC 61000-4-4 was induced, it was soon suppressed to 600 V.

• Korean Journal of Optics and Photonics
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• v.14 no.6
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• pp.600-605
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• 2003

We have experimentally demonstrated a Direct Optical Switching (DOS) CDMA for future wide-band mobile communication systems at the 40 ㎓ band by using orthogonal (crosscorrelation $\leq$2) unipolar type codes with code length of 16 and chip rate of 2.5 Gcps for radio-over-fiber (RoF) systems. Pulse-amplitude-equalized 40 ㎓ laser pulses were provided by rational-harmonically mode-locking a 10 ㎓ fiber ring laser.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.680-683
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• 2001

본 논문은 대기에 의한 흡수율이 매우 큰 60GHz 대역에서의 전파 특성을 이용하여 근거리 차량간 통신 시스템에 적용하여 시스템을 분석한다. 근거리 차량간 통신에서는 전파환경이 직접파와 지면반사파 그리고 측면 차량, 도로벽면에 의한 다중경로가 존재하는 라이시안 분포의 특성이 존재하며 이러한 특성을 고려하여 밀리미터파 분석에 효율적인 Raytracing방법을 도입하여 차량간 통신 시스템을 분석한다. 또한 차량간 통신은 운전자의 안전성과 연결되어지기 때문에 매우 높은 신뢰성이 요구되어지며 따라서 MC-CDMA/QPSK 방식을 도입하여 시스템의 신뢰성을 확보하였으며 수신 성능 향상을 위한 개선기법으로는 BCH 부호화 기법을 적용하여 시스템의 성능을 비교 분석 한다.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1803-1805
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• 2000

This paper analyzes the effects of Ge profiles shape of SiGe heterojunction bipolar transistors (HBT's) for high frequency application. Device simulations using ATLAS/BLAZE for the SiGe HBT with trapezoidal or triangular Ge profile are carried out to optimize the device performance. An HBT with 15% triangular Ge profile shows higher cut-off frequency and DC current gain than that with 19% trapezoidal Ge profile. The cut-off frequency and BC gain are increased from 42GHz to 84GHz and from 200 to 600, respectively.