• 마이크로전자및패키징학회지
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• 제11권3호
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• pp.31-36
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• 2004

연자성 차폐필름에 대하여 ASTM 방법 및 2-port flanged coaxial line 방법으로 RF (radio-frequency) 영역에서 전자기파 차폐특성을 측정하여 원역장에서의 차폐요인을 정량적으로 분석하였다. 4-13.5 GHz의 고주파 영역에서 연자성 차폐필름의 차폐효과는 반사손실에 의한 효과가 아니라 주로 흡수손실에 의한 차폐효과를 가졌다.

• 천문학회보
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• 제38권2호
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• pp.59.1-59.1
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• 2013

Type Ia supernovae (SNe) are providing the most conclusive evidence for accelerating universe with dark energy in observational cosmology. In these investigations, look-back time evolution of SNe luminosity is regarded as negligible on the basic assumption. However, several recent works present some systematic differences among hosts which have different characteristics of stellar population. For more direct investigation, we are proceeding with our YONSEI (YOnsei Nearby Supernovae Evolution Investigation) project. Only early-type hosts in our catalogue were chosen in order to estimate the luminosity-weighted mean age and metallicity directly using Single Stellar Population (SSP) models and ignore the effect from the dust extinction. Observations using low-resolution spectrographs are still in progress at Las Campanas Observatory with 2.5m telescope and at McDonald Observatory with 2.7m telescope. We have thus far obtained spectra for 30 early-type hosts. After weak emission line correction, Lick/IDS absorption-line indices are measured and YEPS spectroscopic evolution model was applied to determine mean population ages and metallicities. Our preliminary results show that SNe Ia hosted in older galaxies seem to be brighter at 1.4 - 3 sigma levels, however, more observations and analyses are still needed to confirm this correlation.

• Ocean Science Journal
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• 제42권1호
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• pp.49-59
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• 2007

Besides empirical algorithms with the blue-green ratio, the algorithms based on fluorescence are also important and valid methods for retrieving chlorophyll-a concentration in the ocean waters, especially for Case II waters and the sea with algal blooming. This study reviews the history of initial cognitions, investigations and detailed approaches towards chlorophyll fluorescence, and then introduces the biological mechanism of fluorescence remote sensing and main spectral characteristics such as the positive correlation between fluorescence and chlorophyll concentration, the red shift phenomena. Meanwhile, there exist many influence factors that increase complexity of fluorescence remote sensing, such as fluorescence quantum yield, physiological status of various algae, substances with related optical property in the ocean, atmospheric absorption etc. Based on these cognitions, scientists have found two ways to calculate the amount of fluorescence detected by ocean color sensors: fluorescence line height and reflectance ratio. These two ways are currently the foundation for retrieval of chlorophyll-a concentration in the ocean. As the in-situ measurements and synchronous satellite data are continuously being accumulated, the fluorescence remote sensing of chlorophyll-a concentration in Case II waters should be recognized more thoroughly and new algorithms could be expected.

• 전기학회논문지P
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• 제66권3호
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• pp.129-134
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• 2017

We investigated theoretically the quantum optical transition properties of Si, in quasi 2-Dimensinal Landau splitting system, based on quantum transport theory. We apply the quantum transport theory (QTR) to the system in the confinement of electrons by square well confinement potential under linearly polarized oscillating field. We use the projected Liouville equation method with Equilibrium Average Projection Scheme (EAPS). In order to analyze the quantum transition, we compare the temperature and the magnetic field dependencies of the QTLW and the QTLS on four transition processes, namely, the intra-leval transition process, the inter-leval transition process, the phonon emission transition process and the phonon absorption transition process.

• 천문학회보
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• 제39권2호
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• pp.58.1-58.1
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• 2014

Energetic gas outflows from active galactic nuclei (AGNs) may have a crucial role in galaxy evolution. In this contribution, we present a census of ionized gas outflows using a large sample (~23,000) of local (z < 0.1) type-2 AGNs selected from the Sloan Digital Sky Survey DR 7. By measuring the velocity offset of narrow emission lines, i.e., [O III] ${\lambda}5007$ and the Balmer lines, with respect to the systemic velocity measured from the stellar absorption lines, we find ~47% of AGNs showing an [O III] line-of-sight velocity offset ${\geq}20km\;s-1$. The fraction in type-2 AGNs is similar to that in type-1 AGNs after considering the projection effect. AGNs with larger [O III] velocity offsets, in particular with no or weak $H{\alpha}$ velocity offsets, tend to have higher Eddington ratios, implying that the [O III] velocity offset is related to on-going black hole activity. Also, we find the different distributions of the host galaxy inclination between the AGNs with blueshifted [O III] and the AGNs with redshifted [O III], supporting the model of biconical outflow with dust obscuration. Meanwhile, for ~3% of AGNs, [O III] and $H{\alpha}$ exhibit comparable large velocity offsets, suggesting a more complex gas kinematics than decelerating outflows in the narrow-line region.

• 천문학회보
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• 제37권1호
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• pp.88.1-88.1
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• 2012

We observed a surge associated with an Ellerman bomb using the Fast Imaging Solar Spectrograph(FISS) of the New Solar Telescope at Big Bear Solar Observatory. The surge was seen in absorption and varied rapidly both in H alpha and Ca II 8542 line. It originated from the Ellerman bomb, and was impulsively accelerated to 20km/s of the blueshift(upward) motion. Then the gradual change from blueshift of 20km/s to redshift of 40km/s occurred in 20 minutes. Based on the measured line-of-sight velocities, we estimated the material reached up to about 5,000km height. We inferred physical parameters of the surge by adopting the cloud model, and found that the temperature of the surge material was about 25,000K and the non-thermal velocity was about 10km/s. Our results suggest that the surge might be heated intensely after it was ejected from the Ellerman bomb.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.171-171
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• 1999

We studied the charge redistribution in the Pt-M (M=Cu, Co) alloys by X-ray Absorption Near Edge Spectroscopy(XANES) and X-ray Photoelectron Spectroscopy(XPS). These analysis tools provide us information about the charge transfer in the valence band of intermetallic bonding. The samples were prepared by arc-melting method. After annealing this samples in vacuum for several hours, we cold get the ordered samples, which were confirmed with XRD analysis. the core and valence level energy shift in these system were investigated by Mg $K\alpha$(1253.6eV) x-ray source for Pt-Co alloys and monochromatized Al $K\alpha$ (1486.6eV) for Pt-Cu alloys. Pt L2, L3-edge, and Cu, Co K-edge XANES spectra were measured with the total electron-yield mode detector at the 3Cl beam line of the PLS (Pohang light source0. from the changes of White line (WL) area and the core level shifts of the each metal sites, we can obtain the information about the electrons participating in the intermetallic bonding of the Pt-Cu and Pt-Co alloys.

• Journal of Advanced Marine Engineering and Technology
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• 제23권3호
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• pp.360-368
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• 1999

The paper describes spectroscopic characteristics of plasma induced in the pulsed YAG laser welding of alloys containing a large amount of volatile elements. The authors have conducted the spectroscopic analyses of laser induced Al-Mg alloys plasma in the air and argon atmosphere. In the air environment the identified spectra were atomic lines of Al, Mg, Cr, Mn, Cu, Fe and Zn and singly ionized Mg lines as well as the intense molecular spectra of ALO and MgO formed by chemi-cal reactions of evaporated Al and Mg atoms from the pool surface with oxygen in the air. In argon atmosphere MgO and AlO spectra vanished but AlH spectrum was detected. the hydrogen source was presumable hydrogen dissolved in the base metals water absorbed on the surface oxide layer or $H_2$ and $H_2O$ in the shielding gas. The resonant lines of Al and Mg were strongly self-absorbed in particular self-absorption of the Mg line was predominant. These results show that the laser induced plasma was made of metallic vapor with relatively low temperature and high density.

• 한국강구조학회 논문집
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• 제10권2호통권35호
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• pp.291-301
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• 1998

종리브로 보강된 충전형 원형강관에 H형강보를 사용한 접합부 모델실험 결과와 항복선이론 및 수치해석을 이용하여 접합부 국부내력의 추정을 위한 기초 자료를 제시하고 궁극적으로는 원형강관 접합부의 보강법을 연구하여 다이아프램이 없는 콘크리트 충전강관 기둥-H형강보 접합부의 개발을 위한 기초자료를 제시하고자 한다.

• 천문학회지
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• 제48권6호
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• pp.399-412
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• 2015

We study the radio properties at 1.4 GHz of Seyfert galaxies with strong forbidden highionization lines (FHILs), selected from the Sloan Digital Sky Survey - a large-sized sample containing nearly equal proportion of diverse range of Seyfert galaxies showing similar redshift distributions compiled by using the Very Large Array survey images. The radio detection rate is low, 49%, which is lower than the detection rate of several other known Seyfert galaxy samples. These galaxies show low star formation rates and the radio emission is dominated by the active nucleus with ≤10% contribution from thermal emission, and possibly, none show evidence for relativistic beaming. The radio detection rate, distributions of radio power, and correlations between radio power and line luminosities or X-ray luminosity for narrow-line Seyfert 1 (NLS1), Seyfert 1 and Seyfert 2 galaxies are consistent with the predictions of the unified scheme hypothesis. Using correlation between radio and [O III] λ 5007 Å luminosities, we show that ∼8% sample sources are radio-intermediate and the remaining are radio-quiet. There is possibly an ionization stratification associated with clouds on scales of 0.1-1.0 kpc, which have large optical depths at 1.4GHz, and it seems these clouds are responsible for free-free absorption of radio emission from the core; hence, leading to low radio detection rate for these FHIL-emitting Seyfert galaxies