• 천문학회보
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• 제40권1호
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• pp.63.1-63.1
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• 2015

In this study, we determine coronal electron density distributions by analyzing DH type II radio observations based on the assumption: a DH type II radio burst is generated by the shock formed at a CME leading edge. For this, we consider 11 Wind/WAVES DH type II radio bursts (from 2000 to 2003 and from 2010 to 2012) associated with SOHO/LASCO limb CMEs using the following criteria: (1) the fundamental and second harmonic emission lanes are well identified; (2) its associated CME is clearly identified in the LASCO-C2 or C3 field of view at the time of type II observation. For these events, we determine the lowest frequencies of their fundamental emission lanes and the heights of their leading edges. Coronal electron density distributions are obtained by minimizing the root mean square error between the observed heights of CME leading edges and the heights of DH type II radio bursts from assumed electron density distributions. We find that the estimated coronal electron density distribution ranges from 2.5 to 10.2-fold Saito's coronal electron density models.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.568-570
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• 2004

A shielding effectiveness of mesh screen filter of plasma display panel (PDP) has been calculated in this paper. Since the screen filter is located near the radiation source, the near field wave impedance of the radiation source, i.e., the PDP electrodes, has been considered to calculate the shielding effectiveness. The near field shielding effectiveness of screen filter at 30${\sim}$300 MHz has been estimated to be more than 65${\sim}$80 dB. The measured shielding effectiveness of screen filter is 10${\sim}$50 dB at 30${\sim}$300 MHz[1]. The resulting discrepancy indicates that there are other EMI emission sources such as emission from PCB and cable besides the PDP electrodes.

• 한국전자파학회논문지
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• 제20권12호
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• pp.1272-1278
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• 2009

본 논문은 신호 전송용 비아가 있는 4층 PCB(Printed Circuit Boards)의 P/G(power/ground)면 사이에서 발생되는 공진을 상쇄시켜 복사성 방사(RE: Radiated Emission) 성능을 개선할 수 있는 기법을 제안하였다. 면간 공진 상쇄를 확인하기 위하여 비아가 있는 4층 PCB에서 신호 전송 선로의 전송 특성, PCB 개방 모서리를 통한 방사(radiation)와 RE 세기를 계산하고, 측정하여 제안된 기법의 타당성을 입증하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.611-615
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• 2004

In recent, there have been several developments in lamp technology that promise savings in electrical power consumption and improved quality of the lighting space. Above all, Electrodeless fluorescent lamp is the removal of internal electrodes and heating filaments that are a light-limiting factor of conventional fluorescent lamps. The electrodeless fluorescent lamp is intended as a high efficacy replacement for the incandescent reflector lamp in many applications. Therefore, the electrodeless fluorescent lamps is substantially higher than that of conventional fluorescent lamps and last up to 60,000 hours. In this paper, electron temperature and electron density were measured in a radio-frequency inductively coupled plasma using a Langmuir probe method for emission characteristics. Measurement was conducted in an argon discharge for pressure from 10 [mTorr] and input RF power 100 [W] to 150 [W]. As for the electron density, a electron temperature was more distinguished for a emission characteristic. The results of ideal may contribute to systematic understanding of a electrodeless fluorescent lamps of emission characteristics.

• 전기전자학회논문지
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• 제20권1호
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• pp.54-60
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• 2016

본 연구에서는 우리나라 DTV 방송의 대역외발사강도 기술기준 및 기존 측정방식의 문제점들을 분석하였으며, 지상파 DTV 방송의 대역외발사강도를 효과적으로 측정할 수 있는 방안들을 제안하였다. 고가의 전용 측정장비로만 측정가능한 기존방식에 비해 제안한 방식은 범용장비로도 대역외발사강도를 손쉽게 측정할 수 있으며, 실제 측정시스템 구현을 통하여 제안한 방식의 유효성을 입증하였다. 본 논문에서 제안된 방식은 경제적이고도 간편하므로 방송장비 이외의 무선 송신장치 특성측정에도 널리 사용될 수 있다.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.409-414
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• 2005

본 논문에서는 최근 CISPR(국제무선장해 특별위원회: International Special Committee on Radio Interference)에서 논의된 1 GHz 이상 주파수 대역의 방사 장해 전자파 측정을 위한 시험방법에 대해서 설명하고, 측정 안테나의 $\theta_{3dB}$ 특성에 따른 w(측정 범위)에 대해 설명하였다. 또한 1 GHz 이상 주파수 대역에서의 측정법 및 한계치에 대한 IEC 규격 개정 상황을 설명하였다.

• 천문학회지
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• 제46권6호
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• pp.235-242
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• 2013

We compare mass-loss rates of OH/IR stars obtained from radio observations with those derived from the dust radiative transfer models and IR observations. We collect radio observational data of OH maser and CO line emission sources for a sample of 1533 OH/IR stars listed in Suh & Kwon (2011). For 1259 OH maser, 76 CO(J=1-0), and 55 CO(J=2-1) emission sources, we compile data of the expansion velocity and mass-loss rate. We use a dust radiative transfer model for the dust shell to calculate the mass-loss rate as well as the IR color indices. The observed mass-loss rates are in the range predicted by the theoretical dust shell models corresponding to $\dot{M}=10^{-8}M_{\odot}/yr-10^{-4}M_{\odot}/yr$. We find that the dust model using a simple mixture of amorphous silicate and amorphous $Al_2O_3$ (20% by mass) grains can explain the observations fairly well. The results indicate that the dust radiative transfer models for IR observations generally agree with the radio observations. For high mass-loss rate OH/IR stars, the mass-loss rates obtained from radio observations are underestimated compared to the mass-loss rates derived from the dust shell models. This could be because photon momentum transfer to the gas shell is not possible for the physical condition of high mass-loss rates. Alternative explanations could be the effects of different dust-to-gas ratios and/or a superwind.

• 천문학회보
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• 제43권1호
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• pp.55.1-55.1
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• 2018

Studies on rotation-powered pulsars with strong surface magnetic field may help us clarify the unclear link between magnetars and canonical radio pulsars because the magnetar-like emission is expected to be observed. PSR J1119-6127 associated with SNR G292.2-0.5 has a high magnetic field of $4.1{\times}1013$ gauss, and a young characteristic age of ~1700 years can be served as the good candidate to compare with magnetars and rotation-powered pulsars. The glitch accompanied by the radiative changes detected in 2007 is the first case we observed for a rotationally powered radio pulsar. This pulsar experienced magnetar-like outbursts in mid. 2016, similar to the 2006 transition occurred on the other radio-quiet rotation-powered pulsar with strong surface magnetic field, PSR J1846-0258. In this talk, I'll report the investigation with X-ray and gamma-ray data of this magnetar-like pulsar. A sudden decrease in the gamma-ray emission at the GeV band was detected immediately after the X-ray outburst. Accompanying with the disappearance of the radio pulsation, the gamma-ray pulsation cannot be resolved as well after the outburst. We tried to derive the timing behavior and some intriguing features of this pulsar in this work corresponding to the outburst using the Swift data, NuSTAR and XMM observations.

• Transactions on Electrical and Electronic Materials
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• 제11권1호
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• pp.29-32
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• 2010

In this study, transparent and conductive Al-doped zinc oxide (AZO) films were prepared on a glass substrate by an radio frequency (RF) magnetron sputtering method using a 150-nm-thick AZO target (Al: 2 wt.%) at room temperature. We investigated the effects of RF power between 100-350 W (in steps of 50 W) on the structural, electrical, and optical properties of the AZO films. The thickness and cross-sectional images of the films were observed by field emission scanning electron microscopy. The thicknesses of all films were kept constant at 150 nm and grown on a glass substrate. The grain sizes of the AZO films were determined with the X-ray diffraction by using the Scherrer' equation, and their electrical properties were investigated using a Hall effect electronic transport measurement system. The transmittance of the AZO films was also measured by an ultraviolet-visible spectrometer.

• ETRI Journal
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• 제29권2호
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• pp.234-236
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• 2007

Interference effects of ultra-wideband devices using the frequency band from 3.1 to 10.6 GHz on wireless broadband are evaluated. The ultra-wideband emission power spectral density that would be necessary to protect a wireless broadband station is considered. Also, an analytic scheme based on a system level simulation of a WiBro system is proposed.