• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2145-2152
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• 2016

Internet generalization has led to increased demands for Internet banking. Various security programs to protect authentication information are being developed; however, these programs cannot protect the wireless communication sections of wireless keyboards. In particular, vulnerabilities have been reported in the radio communication sections of 27 MHz wireless keyboards. In this paper, we explain how to analyze M's 27 MHz wireless keyboard. We also experimentally show that an attacker can acquire authentication information during domestic Internet banking using a 27 MHz wireless keyboard. To do this, we set up an experimental encironment to analyze the electromagnetic signal of a 27 MHz wireless keyboard.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.04a
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• pp.132-133
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• 2007

2개의 주파수가 인가된 유도결합 플라즈마(ICP)를 이용하여 주파수 조합(13.56 or 27.12/2MHz)과 안테나의 캐패시턴스 변화에 따른 $SiO_2$ 와 poly-Si 의 식각특성을 연구하였다. 본 실험의 결과로, 27.12 MHz에서 plasma density가 높다는 것과 13.56 MHz에서 center high profile이 쉽게 형성됨을 알 수 있었다. $SiO_2$ 식각에서는 non-uniformity와 etch rate모두 27.12 MHz가 13.56 MHz보다 높다는 것을 알 수 있었고, poly-Si 식각에서는 non-uniformity와 etch rate모두 비슷한 경향을 나타낸다는 것을 알 수 있었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.1
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• pp.1-7
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• 2001

WRC-2000 adopted the Regions 1 and 3 BSS and associated feeder-link Plans as well as the Regions 1 and 3 BSS and associated feeder-link Lists. These Regions 1 and 3 BSS and associated feeder-link Plans provide, in general, each country of Region 1 with 10 digital channels of 27MHZ bandwidth and each country of Region 3 with 12 digital channels of 27MHZ bandwidth. In this study, we summarize the results of associated meetings and analyze the effects of BSS replanning in Korea. We study the effective interference analysis through the review of Radio Regulations and associate Resolution. Furthermore, interference analysis of inter-broadcasting satellite systems will be done with MSPACEG S/W.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.10
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• pp.1731-1736
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• 2008

In this paper, singly fed circularly polarized nearly-square patch antenna for receiving S-DMB is presented. It used teflon substrate of relative dielectric constant ${\in}_{\gamma}=2.2$ and the sire is $40{\times}40{\times}15[mm]$. Experimental results of fabricated antenna show that input return loss and axial ratio are about 22MHz, 25MHz at the center resonant frequency, respectively. And fabricated LNA has gain of 27.5 [dB], NF of 1.27 [dB], input return loss of -15.4 [dB] and output return loss of -18.9 dB, respectively. Simulation results and experimental results are good agreements. This proposed antenna is well able to handheld gadgets for receiving S-DMB.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.66.1-66.1
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• 2010

Microcrystalline silicon at low temperatures has been developed using plasma enhanced chemical vapor deposition (PECVD). It has been found that energetically positive ion and atomic hydrogen collision on to growing surface have important effects on increasing growth rate, and atomic hydrogen density is necessary for the increasing growth rate correspondingly, while keeping ion bombardment is less level. Since the plasma potential is determined by working pressure, the ion energy can be reduced by increasing the deposition pressure of 700-1200 Pa. Also, correlation of the growth rate and crystallinity with deposition parameters such as working pressure, hydrogen flow rate and input power were investigated. Consequently an efficiency of 7.9% was obtained at a high growth rate of 0.92 nm/s at a high RF power 300W using a plasma-enhanced chemical vapor deposition method (27.12MHz).

• Journal of Advanced Navigation Technology
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• v.27 no.2
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• pp.209-213
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• 2023

Currently, 2.4 GHz and 5 GHz bands are used as frequencies for drone operation. In December 2019, the Ministry of Science and ICT newly allocated the 433 MHz band for the invisible long-distance operation of drones. However, since the 433 MHz band is the same as the previously allocated frequency band for amateur radio communication, interference cannot be avoided. Therefore, as a prerequisite for the development of a drone operation system based on the 433 MHz band, interference avoidance technology for this frequency band must be developed and applied. In this paper, we report the results of measurement and analysis of 433 MHz band signals necessary for the development of interference avoidance and reduction technologies for 433 MHz signals. The measurement and analysis of the 433 MHz band signal are performed through the spectrum measured at 5-minute intervals at three locations. Since the measurements and analyzes performed in this study considered spatial characteristics, temporal characteristics, and traffic characteristics, it is considered to be the basic data necessary for the development of interference avoidance technology in the 433 MHz band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.1
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• pp.1-7
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• 2016

In this paper, the tunable filter based on high power cavity using mechanical switch for 1.5 GHz band is presented. The LPF is inserted to eliminate the spurious wave, coupler is embeded to extract the output power, and then the tunable filter system is configured using mechanical switch. The LPF obtains attenuation over 40 dB between 4 GHz and 12.75 GHz, Coupler is satisfied with coupling value 40 dB and coupling isolation over 55 dB. The tunable filter system using mechanical switch obtains insertion loss 0.88 dB at bypass mode between 1,495.9 MHz and 1,510. 9 MHz, 3.29 dB at fil mode between 1,495.9 MHz and 1,500.9 MHz. It is also satisfied with output power of 132 W at the center frequency 1,498.4 MHz, and switching time below 10 ms.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.37-44
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• 2020

In this paper, we proposed a compact printed monopole antenna with an inverted L-shaped slot for dual-band operations. Two operating frequency bands are achieved with the use of an inverted L-shaped slot etched on the radiating strip for bandwidth enhancement and a defected ground structure for return loss improvement in the higher frequency band. The measured results showthat the proposed antenna has impedance bandwidths (S₁₁< -10 dB) of 270 MHz (1.81-2.08 GHz) and 340 MHz (2.36-2.70 GHz), covering the required bandwidths for PCS (1850.5-1989.5 MHz), CDMA 2000 (1850-1990 MHz), TD-SCDMA (1880-2025 MHz) and 2.4 GHz WLAN (2400-2484 MHz). The measured return loss of the proposed antenna has a good value of approximately 27.2 dB at 2.4 GHz WLAN. The antenna's peak gains also have a high value of 1.92 dBi at 2 GHz and 2.12 dBi at 2.45 GHz. The proposed antenna shows omnidirectional radiation patterns over the entire frequency range of interest.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3614-3621
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• 2009

In this paper, A CMOS low-voltage current mode integrator is designed. The designed current-mode integrator is based on linear cascode circuit that is newly proposed in this paper. When it is compared with gain(43.7dB) and unity gain frequency(15.2MHz) of the typical current-mirror type current-mode integrator, the proposed linear cascode current-mode integrator achieves high current gain(47.8dB) and unity gain frequency(27.8MHz). And a 5th Chebyshev current-mode filter with 7.03MHz cutoff frequency is designed. The designed all circuits are simulated by HSPICE using 1.8V-$0.18{\mu}m$ CMOS technology.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.2 s.93
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• pp.211-216
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• 2005

In this paper, GPS/PCS/Satellite DMB compact chip antenna is designed using stacked meander line for mobile communication handset. The fabricated antenna size is $12.52mm\times19.95\times1.05mm$. The coupling is adjusted by via and arrangement among meander lines to improve FR(Frequency Ratio) and return-loss. The fabricated antenna achieve triple-band. The resonance frequencies are 1.696 GHz, 1.888 GHz and 2.680 GHz. The impedance bandwidths are 150 MHz, 120 MHz and 60 MHz. The maximum gains of antenna are 0.08 dBi, 1.70 dBi and -1.27 dBi at resonance frequencies.