• 한국의류산업학회지
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• 제6권6호
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• pp.810-814
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• 2004

This study is one of the fundamental researches for the development of future smart clothing and textile products using silver(Ag) nano powder. Our study was focused on the blocking or insulating effects of nano-processed textiles from electromagnetic waves. Also, for the surveying of the actual effect to human body, we measure the variation of electroencephalogram which is an indication of human physical symptoms. Among various textiles in this experiment, nano silver processed case has shown the best blocking performance from the electromagnetic waves, which decreases depending on the distance. As a reference model of working environment, we setup the visual stimuli object on the computer that is a source of electromagnetic wave. The power spectrum distribution and the incidence of electroencephalogram was measured. The analysed data has shown that, with nano-processed textiles, ${\beta}$ wave does not appear very often where ${\beta}$ wave appears only to illustrate the stable states of human's body. However, as for the materials without nano processing, the ratio of ${\gamma}$ waves in the total level of electroencephalogram becomes higher in spite of short exposure to visual stimuli in work environment, which shows that the worker becomes stressed. The ${\beta}$ wave electroencephalogram of all materials is drawn in calcarine fissure of occipital lobe to show the convergent distribution, and stronger with block-processed Nano Silver Silk(NSS). The study based on the potential risks of human diseases such as physical fatigue by electromagnetic waves, and has shown that the application of Nano Silver textile for human uses require a proper particle size of it which would not penetrate cellular tissues, and a proper binder and binding treatment for it. However, it is highly required for back-up researches to verify various aspects in applying nano silver to textile products.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.60-63
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• 2001

Investigating electromagnetic emissions of inverter power sources for resistance welding existing special aspects of EMI measurements in the field of resistance welding machines resulting from the power rating and intermittent operation mode of these machines have to be taken into account. The characteristics of the internal switching processes determined by the behavior of the applied power semiconductors, snubber circuits and constructional aspects exert a great influence on the conducted emission of resistance welding inverters.

• 전기의세계
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• 제27권5호
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• pp.5-12
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• 1978

1.Power utilities and CRIEPI are very active in almost all aspects of power systems research. 2.About 50% of research activity of CRIEPI is made under the joint work with power utilities. 3.Research motivation of manufactures are mainly stimulated by the need of power utilities and manufacturers are closely collaborating with power utilities. 4.Main effort of universities is concentrated upon the theoretical aspects of network analysis and the means of stability improvement. Univer sities are doing research rather independently of industry unless inexceptional cases. 5.Universities are making a significant contribution to the exploration of new horizon of power systems engineering, namely, in the research on the social impact on the future of power system. 6.Current main interest of power systems reserch is centered around the stability problem and power system operation and control. Research activity in power system planning is rather low as compared to that in these two major fields. A similar statement holds for the analysis of electromagnetic transients and short circuit analysis. However a new research field is sprouting in the area of power system protection.

• 한국안전학회지
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• 제11권4호
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• pp.49-53
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• 1996

Corona discharges in air insulated electric power systems cause power loss, produce interfering electromagnetic radiation, and can indicate incipient failure. An understanding of corona discharges in air gap is clearly Important. The Wavelet transformation is an extended method of fourier transformation. The fourier method is a powerful tool for signal analysis, but it can't include information for time. However the wavelet transformation analysis can include on the information of time and frequencies at the same time. In this paper we apply the wavelet transformation to the corona signals in needle-plane air gap for the purpose of analysis of developing aspects of corona discharges. We analyzed the developing aspects of corona discharges, namely, corona discharge current, repetition rates, width of Pulse distribution region, pulseless region and frequencies distribution of corona discharge pulses.

• Journal of Power Electronics
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• 제2권2호
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• pp.124-129
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• 2002

Invertigation electromagnetic emissione of inverter power sources resistance welding existing special aspects of EMI measurements in the field of resistance welding machines resulting from the power rating and operation mode of these machines have to be taken into account. The characteristics of the internal switching processes determined by the behavior of the applied power semiconductors, sunbber circuits and constructional aspect exert a great influence on the conducted emission welding inverters.

• Journal of electromagnetic engineering and science
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• 제12권4호
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• pp.290-292
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• 2012

This paper proposes a setup for a best multisine design method that uses a time-domain optimization. The method is based on minimization of the time-domain error, so its resulting multisine has a very accurate ACLR estimation. This is because its probability distribution and sample-to-sample correlation are close to those of the original signal, which are crucial for the testing of nonlinear power amplifiers. In addition, a hyperbolic-tangent function is introduced to control the ripple of tone magnitudes within signal bandwidth. For the verification, multisines were generated and compared for many aspects such as normalized error, in-band ripple, and ACLR estimation. Test results with different numbers of tones provide supporting evidence that the suggested multisine design has better ripple suppression, by up to 7 dB, and better accuracy, by up to 0.2 dB, when compared to the conventional method. The accuracy of the ACLR was improved by about 5 dB when the number of tones was 4. The suggested method improves the ACLR estimation performance of multisine testing due to its closer resemblance to the target modulation signal.

• Journal of electromagnetic engineering and science
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• 제17권3호
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• pp.138-146
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• 2017

A phase-locked dielectric resonator oscillator (PLDRO) is an essential component of millimeter-wave communication, in which phase noise is critical for satisfactory performance. The general structure of a PLDRO typically includes a dual loop of digital phase-locked loop (PLL) and analog PLL. A dual-loop PLDRO structure is generally used. The digital PLL generates an internal voltage controlled crystal oscillator (VCXO) frequency locked to an external reference frequency, and the analog PLL loop generates a DRO frequency locked to an internal VCXO frequency. A dual loop is used to ease the phase-locked frequency by using an internal VCXO. However, some of the output frequencies in each PLL structure worsen the phase noise because of the N divider ratio increase in the digital phase-locked loop integrated circuit. This study examines the design aspects of an interconnected PLL structure. In the proposed structure, the voltage tuning; which uses a varactor diode for the phase tracking of VCXO to match with the external reference) port of the VCXO in the digital PLL is controlled by one output port of the frequency divider in the analog PLL. We compare the proposed scheme with a typical PLDRO in terms of phase noise to show that the proposed structure has no performance degradation.

• 한국전자파학회논문지
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• 제29권6호
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• pp.457-463
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• 2018

이 논문에서는 실제 레이다를 이용하여 획득한 신호와 시뮬레이션으로 획득한 신호에 ${\Sigma}{\Delta}-STAP$ 알고리즘을 적용하여 비교하였다. 시험은 무반향 챔버에서 모의신호 발생장치를 이용한 표적 신호와 신호발생기를 이용한 클러터 신호를 레이다로 수신하여 수행하였다. 시뮬레이션은 시험과 동일한 레이다 파라미터에 이상적인 기저대역 신호 모델링을 통하여 수행하였다. 비교 결과, ${\Sigma}{\Delta}-STAP$ 처리된 거리-도플러 맵은 표적 신호의 형태나 잡음 수준이 시뮬레이션과 시험 결과가 거의 유사하였다. SINR 손실의 경우, 두 결과가 비슷한 양상을 보이나, 시뮬레이션 결과가 1~2 dB 가량 높은 값을 보였다. 이를 통하여 일반적인 레이다 신호 시뮬레이션을 수행하여도 실제 시험 결과와 유사한 ${\Sigma}{\Delta}-STAP$ 처리 결과를 얻을 수 있음을 확인하였다.

• 한국전자파학회논문지
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• 제24권8호
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• pp.860-872
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• 2013

본 논문은 국내외 재난통신망 구축 현황과 기술 발전을 조사 분석하여 합리적이고 효율적인 재난통신망 구축 방안을 제시한다. 연구한 결과, 우리나라는 TRS 기반의 재난통신망이 전국 규모로 구축되어 있지 못한 상황에서 완전 재난통신 광대역 자가망으로 진화하기 위해서는 5년 이상의 과도기적인 재난통신망 구축 및 운영이 불가피하다. 따라서 광대역 이동 통신 기술 기반의 자가망을 구축하면서 이 기술이 성숙될 때까지 상용 TRS와 상용 모바일 광대역망을 보완 활용하는 것이 필요하며, 이를 구체적으로 설계하고 검증하기 위한 전담 조직의 설립이 적극적으로 검토될 필요가 있다.

• 한국전자파학회논문지
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• 제21권11호
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• pp.1229-1234
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• 2010

차세대 이동 통신에서는 고품질, 고속 통신의 멀티미디어 서비스를 요구한다. 이러한 서비스를 만족시키기 위해서는 강력한 오류 정정 기법이 사용된다. ARQ(Auto Repeat Request) 기법은 전송 효율적인 측면, 그리고 FEC(Forward Error Correction) 기법은 높은 신뢰도면에서 취약한 단점을 가지고 있다. 이러한 단점을 서로 보완한 H-ARQ(Hybrid Auto Repeat Request) 시스템이 현재 연구 중에 있다. 따라서 본 논문에서는 cross layer를 이용한 H-ARQ 시스템을 분석하였다. Cross layer coding 기법과 H-ARQ type, 채널 환경에 따라 적합한 H-ARQ 방식을 BER 성능과 전송 효율 분석을 통해 제안한다.