• Korean Journal of Medicinal Crop Science
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• v.18 no.6
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• pp.373-378
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• 2010

In order to obtain basic data for utilization of the aerial parts of Cnidium officinale Makino (APCO), the antioxidant properties of the aerial parts and rhizomes of C. officinale were measured using DPPH and ABTS radicals, and nitrite scavenging assays. The ethyl acetate (EA) fraction prepared from the aerial parts of APCO showed the strongest antioxidant activities, and contained high level of total phenolic compounds (325.81 mgTE/g) and flavonoids (259.16 mgRE/g). The concentrations for 50% reductions ($RC_{50}$) values of the DPPH and ABTS radicals, and nitrite by the EA fraction of APCO were $11.27\;{\mu}g/m{\ell}$, $14.34\;{\mu}g/m{\ell}$, and $10.26\;{\mu}g/m{\ell}$, respectively. APCO exhibited approximately 3-9 times higher antioxidant activity than rhizomes of C. officinale. The antioxidant capacities of APCO were positively correlated with its total phenolic contents. Therefore, it was concluded that the aerial parts of C. officinale can be a useful and cost-effective source of natural antioxidant for food or cosmetics.

• 건강소식
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• v.6 no.8 s.46
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• pp.7-9
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• 1982

• 건강소식
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• v.6 no.10 s.48
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• pp.4-5
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• 1982

• 건강소식
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• v.7 no.10 s.59
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• pp.7-11
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• 1983

• 건강소식
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• v.9 no.8 s.81
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• pp.9-13
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• 1985

• 건강소식
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• v.6 no.10 s.48
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• pp.38-40
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• 1982

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.6 s.97
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• pp.603-614
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• 2005

In this paper, digital ultra-narrowband Walky-Talky using direct conversion method for CQPSK modulation scheme is implemented with satisfying the requirements of APCO P25. RF transceiver design and implementation scheme that minimize the influence of DC-offset and AC-coupling at ultra-narrowband is proposed. This scheme also minimizes the influence of nonlinear characteristic at power amplifier fir CQPSK modulation method. Test results of full system including DSP module and direct conversion RF transceiver show that FCC emission mask at 36.8 dBm PEP meets the standard requirements. The characteristic of receiver AGC by PWM control signal is linear at 40 dB dynamic range and voice communication at input power level of -116 dBm is successful. Also it is verified that the performance of BER versus frequency offset and versus SNR meets the standard requirements.

• Journal of electromagnetic engineering and science
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• v.4 no.2
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• pp.72-78
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• 2004

In this paper, we evaluate the performance of the digital modulation schemes described in the APCO Project 25 FDMA specifications which can be used for applying the ultra-narrowband technology to the current domestic simple two-way radio systems, and discuss difficulties in the DSP implementation of the systems. We analyze the effect on the systems' BER performance of receiver non-matched filter and frequency-offset between the transmitter and receiver oscillators. And we present a frequency offset compensation method for improving the system performance. The results of performance analysis showed that the CQPSK of APCO Project 25 using non-matched filter degraded the BER by 0.5～1.0 ㏈ comparing with PI/4 DQPSK using matched filter. In the event of 2 % frequency offset, about 1 ㏈ performance loss was produced at the BER of $$10^{-3}TEX>. With the frequency-offset compensation method implemented in the systems using phase recovery scheme of PSK synchronization detection, the performance degradation of about 1.0 ㏈ was occurred at the BER of $$10^{-3}TEX> for 10 % of frequency offset. The proposed method can be used for the improvement of system performance.

• Information and Communications Magazine
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• v.29 no.5
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• pp.3-9
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• 2012

본 논문에서는 재난 통신 및 네트워크 기술 그리고 앞으로의 발전 방향에 대해서 소개 하고자 한다. 제 1장에서는 주요 공공재난안전통신 기술들을 소개한다. 특히 동적 그룹통신기술(Push-To-Talk), 망 복구 및 생존성 향상 기술, 긴급호 구현 기술을 소개하며 또한 재난통신기술 표준화 필요성에 대해서 간단히 설명한다. 제 2장에서는 국내외 재난통신기술 동향을 살펴본다. 특히 미국, 유럽, 아시아에서 사용하는 주파수 대역 및 협대역 및 준광대역 주파수 공용 무선통신 기술인 TETRA(Terrestrial Trunked Radio), iDEN(Integrated Digital Enhanced Network) 및 APCO-P25(Association of Public Safety Communications Officials - Project 25)에 대해서 다룬다. 제 3장에서는 재난대비 미래 광대역 통신체계에 대해서 설명하며 마지막으로 제 4장에서는 본 논문의 결론을 맺는다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.5
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• pp.510-518
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• 2010

In this paper, the designed and implemented results of CFL linearization chip which can be used in mobile radio and TRS terminal of UHF band(380~910 MHz), using $0.6\;{\mu}m$ BiCMOS process based on Si, are shown. As gain control circuits for modifying transmit power are inserted not only in feedback path but also in forward path, the stability of CFL is maintained. And, DC-offset correction function of S/H structure, which is suitable for walkie-talkie PTT operation and is easily implemented, is realized. The performance test results of transmitter show that the regulation of FCC emission mask at PEP 3 W(34.8 dBm) is satisfied when the CQPSK modulated signal is fed and more than 30 dBc improvement of 3rd order IMD is achieved when two-tone signal is inputted.