• Journal of Communications and Networks
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• v.13 no.3
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• pp.214-220
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• 2011

This paper attempts to address the effectiveness of physical-layer network coding (PNC) on the throughput improvement for multi-hop multicast in random wireless ad hoc networks (WAHNs). We prove that the per session throughput order with PNC is tightly bounded as ${\Theta}((n\sqrt{m}R(n))^{-1})$ if $m=(R^{-2}(n))$, where n is the total number of nodes, R(n) is the communication range, and m is the number of destinations for each multicast session. We also show that per-session throughput order with PNC is tight bounded as ${\Theta}(n^{-1})$, when $m={\Omega}(R^{-2}(n))$. The results of this paper imply that PNC cannot improve the throughput order of multicast in random WAHNs, which is different from the intuition that PNC may improve the throughput order as it allows simultaneous signal access and combination.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.1
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• pp.111-116
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• 2017

We propose the compact circular polarized antenna. The radiation elements of the proposed antenna is designed using FR4 substrate with the size of $25mm{\times}3.2mm{\times}5mm$ and stand on four corners of the feed network substrate. The feeder network is designed on FR4 substrate with the size of $40mm{\times}40mm{\times}0.8mm$ and has four oupt signals with same magnitude and $90^{\circ}$ phase difference. The input impedances of the designed radiation elements and the output impedances of the feeder network are $100{\Omega}$. The designed antenna has the dimension of $40mm{\times}40mm{\times}5.8mm$ and the operated frequency band of 1.559 - 1.609 GHz. The fabricated antenna has RHCP radiation pattern and the measured results of axial ratio less than 3.5 dB and radiated gain more than 1.5 dBic. The fabricated antenna can apply to GLONASS and Beiodu systems as well as GPS system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.1
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• pp.114-121
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• 2003

In this paper, low voltage and two stage CMOS Class E RF power amplifier for ISM(Industrial/Scientific/Medical) Open Band is presented. The power amplifier operates at 2.4GHz frequency, and is designed and simulated with a 0.35um CMOS technology and HSPICE simulator. The power amplifier is simple structure of two stage Class E power amplifier. The design procedure determing matching network was presented. The power amplifier is composed of input stage matching network, preamplifier, interstage matching network, power amplifier, and output stage matching network. The matching networks of input stage and interstage were constituted by pi($\pi$) type and L type respectively. At 2.4GHz operating frequency, and with a 2.5V supply voltage, the power amplifier delivers 23dBm output power to a 50${\Omega}$ load with 39% power added efficiency(PAE).

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.4 s.56
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• pp.84-92
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• 2005

본 논문은 CDN(Coupling/Decoupling Network)을 이용한 전자파 전도 내성 시험의 측정 불확도를 연구하였다. 측정 불확도의 영향 인자를 추출하여 인자별 불확도를 산출하였다. 측정 불확도 인자는 인가 레벨 교정시 반복 측정, $150\sim50\Omega$ 아답터의 삽입 손실, 신호 발생기의 정확도, 파워미터의 정확도, 전력 증폭기의 하모닉, 전력 증폭기와 CDN의 부정합, CDN과 파워미터 사이의 부정합에 의한 불확도를 고려하였다. 불확도 산출 결과 확장 불확도는 95% 신뢰 구간에서 1.17 dB(k=)를 가지며, 정보기기의 경우 시험 전압 3 V에서 ${\pm}0.42V$의 오차 범위를 가지는 것을 알 수 있었다. 또한 시험기기간의 부정합에 의한 불확도가 불확도 인자에서 가장 큰 영향을 미치는 것을 알 수 있었으며, 전자파 전도 내성 시험의 경우 임피던스 매칭이 가장 중요한 것으로 나타났다.

• Journal of information and communication convergence engineering
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• v.10 no.4
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• pp.321-328
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• 2012

A novel design for a simple rectangular ring with open-ended monopole antenna wireless local area network (WLAN) applications is proposed in this article. The proposed antenna consists of an open-ended rectangular ring, an inverted L-strip, and a rectangular slit in the ground plane, and is fed by a 50 ${\Omega}$ microstrip feed-line. Prototypes of the proposed antenna were designed, fabricated, and tested. Experimental results show that the proposed antenna receives 2.3125-2.775 GHz and 4.8625-6.7125 GHz with a return loss less than -10 dB, covering the required bandwidths of the 2.4/5.2/5.8 GHz WLAN standards. Meanwhile, the 2D radiation patterns and 3D gain performance of the antenna in the operation bands were also observed and discussed.

• Journal of information and communication convergence engineering
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• v.12 no.1
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• pp.1-7
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• 2014

A novel design of a simple circular ring with open-ended monopole antenna for wireless local area network (WLAN) applications is proposed in this article. The proposed antenna consists of an open-ended circular ring and $50-{\Omega}$ microstrip feed-line. The proposed antenna is capable of generating two separate resonant modes with good impedance-matching conditions. A prototype of the proposed antenna is designed, fabricated, and measured. Acceptable agreement between the measurement and simulation results is achieved. Experimental results show that the proposed antenna has operating bandwidths of 1.99-3.04 GHz and 5.08-6.1 GHz with a return loss of less than -10 dB, covering the required bandwidths of the 2.4/5.2/5.8-GHz WLAN standards. This is a microstrip antenna for IEEE 802.11a/b wireless local area networks applications. Meanwhile, the two-dimensional (2D) radiation patterns and three-dimensional (3D) gain performance of the antenna are also observed and discussed.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.290-292
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• 2002

In this paper, we present a simple design method and measurement results for circular loop antenna arrays, which can be used for LS band operation, such as access point antennas in the wireless LAN system. It has been shown that the input impedance of a circular loop can be adjusted near 100 $\Omega$ using a short stub. The length of the stub can be immediately determined in the work place through the measurement of S11 with a network analyzer. Fabricated arrays show high antenna gains as much as 12.4㏈i and 15.1 ㏈i at the center frequency of 2.45 ㎓ for 4${\times}$l and 4${\times}$2 array, respectively. These types of loop arrays can be fabricated at a low cost.

• Journal of Sensor Science and Technology
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• v.21 no.5
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• pp.385-388
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• 2012

This paper describes the synthesis and characterization of graphene by RTA process. Amorphous 3C-SiC were deposited using APCVD for carbon source and Ni layer were employed for transition layer. Various parameters of the ramping speed, the annealing time and the cooling speed are evaluated for the optimized combination allowed for the reproducible fabrication of graphene using 3C-SiC thin film. For analysis of crystalline Raman spectra was employed. Transferred graphene shows a high IG/ID ratio of 2.73. SEM and TEM images show the optical transparency and 6 carbon network, respectively. Au electrode deposited on the transferred graphene shows linear I-V curve and its resistance is 358 ${\Omega}$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.1
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• pp.49-54
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• 2004

This paper is purpose to manufacture of inhibitor switch using CAM systems. CAM systems are consist of CAD(AutoCAD), CAM(Omega) software and CNC milling machine. CAM software is purpose to G-code generation for CNC programming. Then CAM software and CNC milling machine are connect to RS-232-C cable for data network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.6
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• pp.1425-1432
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• 1998

The propagation properties of Gaussian pulse signals on the microstrip line are investigated by the Kirschning & Jansen's approximated equation to meet the frequency range of a pulse, accuracy, and geometrical requiremtns of the microstrip line. The dispersion of pulse signals is analyzed regarding to the relative permittivity .epsilon.$_{r}$, substrate height h and strip width w of the microstrip line. To verify theoretical results, several samples of 50.OMEGA. microstrip lines are fabricated. And the characteristics of pulse propagation along these lines are simple measured using VNA(Vector Network Analyzer) with time-domain analysis function. A fairly good agreement has been found between the measured pulse waveforms and computer simulations.