• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2249-2254
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• 2008

A non-thermal micron size plasma needle is applicable for medical treatment because it includes radicals, charged particles, ultraviolet emission, and strong electric fields. The electric fields around the plasma needle device driven by a radio frequency wave are investigated in order to calculate the power delivered to the cell. A commercial multi-physics code, CFD-ACE, was utilized for the calculation of electric fields for the optimization of the needle structure. The electric field and energy absorption profiles are presented with the variation of the device structure and the distance between the needle and tissues. The living tissues effectively absorb the radio frequency power from the plasma needle device with the covered pyrex structure.

• Journal of electromagnetic engineering and science
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• v.12 no.2
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• pp.166-170
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• 2012

This paper presents a tunable composite right/left-handed (CRLH) delay line for a delay line discriminator that linearizes modulated frequency sweep in a frequency modulated continuous wave (FMCW) radar transmitter. The tunable delay line consists of 8 cascaded unit cells with series varactor diodes and shunt inductors. The reverse bias voltage of the varactor diode controlled the group delay through its junction capacitance. The measured results demonstrate a group delay of 8.12 ns and an insertion loss of 4.5 dB at 250 MHz, while a control voltage can be used to adjust the group delay by approximately 15 ns. A group delay per unit cell of approximately 1 ns was obtained, which is very large when compared with previously published results. This group delay can be used effectively in FMCW radar transmitters.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.4
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• pp.341-351
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• 2021

In this paper, a GNSS error generation simulator for Signal Quality Monitoring (SQM) is implemented by using Matlab based on mathematical models derived from the effect of GNSS signal and measurement errors. The GNSS signal measurement errors of interest in this paper include three cases such as Evil Wave Form (EWF), Multipath (MP) and Radio Frequency Interference (RFI). In order to verify the validity of the generated measurement errors, a simple form of metrics for detecting and monitoring GNSS errors is included in the simulator. The GNSS errors generated by the simulator are added to the GNSS measurement data from commercial GNSS receiver in real time, and then, the SQM is tested for various scenarios of each case configured by scenario setting of the user.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.9 s.112
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• pp.874-882
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• 2006

We surveyed the international and national spectrum & technical standardization trends of extremely adaptive frequency bands $57\sim64GHz$ that can provide 1 Gbps bit-rate ultra broadband service in above 30 GHz millimeter waves, and analyzed service scenarios and the characteristics of these bands, As a result of these analysises, 1 Gbps ASK channel bandwidth needs 2.5 GHz and total bandwidth calculated 7 GHz for dual FDD. finally, we proposed the nationally suitable allocation plan of millimeter wave bands $57\sim64GHz$.

• Journal of Convergence for Information Technology
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• v.9 no.8
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• pp.134-139
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• 2019

This paper describes the effect of multiple signal regeneration in quadrature digital radio frequency memory(DRFM). Single channel DRFM have good reproducibility after storing a single signal. However, when reproduced after storing multiple signals, the spurious signal is large. The quadrature DRFM consists of I and Q channels, which can greatly reduce the spurious signal. The amplitude of the spurious signal depends on the number of bits of data stored in the DRFM. In this paper, we have obtained the number of bits of signal regeneration according to the application of radio frequency memory by obtaining the size of the spurious signal according to the number of bits of the stored data of the DRFM for multiple signals. As a result of this study, 4 bits quadrature DRFM can achieve a spurious output of less than -20dB, which is used for 4 signals. Those are expected to greatly contribute to the signal analysis of electronic warfare equipment and the development of jamming device.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.307-307
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• 2013

초고집적 회로에 적용되는 반도체 소자의critical dimension (CD)이 수 nano 사이즈로 줄어들고 있기 때문에, 다양한 물질의 식각을 할 때, 건식식각의 중요성이 더 강조되고 있다. 특히 $SiO_2$와 같은 유전체 물질을 식각할 때, plasma process induced damages (P2IDs)가 관찰되어 왔고, 이러한 P2IDs를 줄이기 위해, pulsed-time modulation plasma가 광범위하게 연구되어 왔다. Pulsed plasma는 정기적으로 radio frequency (RF) power on과 off를 반복하여 rf power가 off된 동안, 평균전자 온도를 낮춤으로써, 웨이퍼로 입사되는 전하 축적을 효과적으로 줄일 수 있다. 또한 fluorocarbon plasmas를 사용하여 $SiO_2$를 식각하기 위해 Dual-Frequency Capacitive coupled plasma (DF-CCP)도 널리 연구되어 왔는데, 이것은 기존의 방법과는 다르게 plasma 밀도와 ion bombardment energy를 독립적으로 조절 가능하다는 장점이 있어서 미세 패턴을 식각할 때 효과적이다. 본 연구에서는 Source power에는 60 MHz pulsed radio frequency (RF)를, bias power에는 2 MHz continuous wave (CW) rf power가 사용된 system에서 Ar/$C_4$ F8/$O_2$ 가스 조합으로, amorphous carbon layer (ACL)가 hard mask로 사용된 $SiO_2$를 식각했다. 그리고 source pulse의 duty ratio와 pulse frequency의 효과에 따른 $SiO_2$의 식각특성을 연구하였다. 그 결과, duty ratio의 감소에 따라 $SiO_2$, ACL의 etch rate이 감소했지만, $SiO_2$/ACL의 etch selectivity는 증가하였다. 반면에 pulse frequency의 변화에 따른 두 물질의 etch selectivity는 크게 변화가 없었다. 그 이유는 pulse 조건인 duty ratio의 감소가 전자 온도 및 전자 에너지를 낮춰 $C_2F8$가스의 분해를 감소시켰으며, 이로 인해 식각된 $SiO_2$의 surface와 sidewall에 fluorocarbon polymer의 형성이 증가하였기 때문이다. 또한 duty ratio의 감소에 따라 etch selectivity뿐만 아니라 etch profile까지 향상되는 것을 확인할 수 있었다.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.622-629
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• 2003

Generally, a silicone rubber and a chloride polyethylene(CPE) have been used for the development of high-performance composite EM(ElectroMagnetic) wave absorber. In this study, the EM wave absorption abilities for natural lacquer which is newly suggested in this study as a binder for composite EM wave absorber were investigated to develop an improved EM wave absorber In addition, MnZn ferrite composite EM wave absorber mixed with the natural lacquer were prepared and their absorption ability was also investigated. MnZn ferrite composite EM wave absorber which employs the natural lacquer as a binder showed an improved EM wave absorption characteristics in comparison with the conventional binder such as a silicone rubber and a chloride polyethylene(CPE). The matching frequency and the absorption ability of EM wave absorber mixed with natural lacquer can be controled the change of the thickness of them.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.497-498
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• 2011

In 21 century, we use a variety of new wireless technologies focuses on broadcasting and Communications. Because of widely spread wireless-service, demand a lot of frequency. It requires various wireless access technologies. Especially UWB, SER, Millimeter Wave etc. Among them, UWB can use wide Frequency band, because it is different from Non-traditional approach which Frequency Band Using the exclusive rights granted by. Furthermore, it does not cause interference to other existing frequency, therefore this technology is attracting attention. In this paper, describe study on a UWB technology, design about useable antenna for UWB communication.

• Journal of Advanced Navigation Technology
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• v.10 no.3
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• pp.235-249
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• 2006

In this paper, SER(Symbol Error Rate) variation and effects on SER by phase noise at various frequency offset of the local oscillator in digital communication systems are gerneralyzed for QPSK(Quadrature Phase Shift Keying), MQAM(M-ary Quadrature Amplitude Modulation), OFDM(Orthogonal Frequency Division Multiplex)-MQAM, OFDM-QPSK and 8-VSB(Vestigal Side Bands) modulation methods and compared those with the ideal cases, which have no phase noise, through the MATLAB simulation. And the ration between modulation bandwidths and the SER on the various frequency offsets on the above modulation methods have been analyzed for the system requirement of minimum phase noise characteristics. From this study, we have confirmed that the most sensitive modulation method on the phase noise is OFDM-MQAM and that the relatively insensitive method 8-VSB.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.6
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• pp.504-511
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• 2013

This paper proposes improved detection schemes for concealed micro-electronic devices using clustering and classification of radio frequency harmonics in order to protect intellectual property rights. In general, if a radio wave with a specific fundamental frequency is propagated from the transmitter of a classifier to a concealed object, the second and the third harmonics will be returned as the radio wave is reflected. Using this principle, we exploit the fuzzy c-means clustering and the ${\kappa}$-nearest neighbor classification for detecting diverse concealed objects. Simulation results indicate that the proposed scheme can detect electronic devices and metal devices in various learning environments by efficient classification. Thus, the proposed schemes can be utilized as an effective detection method for concealed micro-electronic device to protect intellectual property rights.