• Journal of Powder Materials
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• v.14 no.4
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• pp.265-271
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• 2007

Electromagnetic wave absorbing materials have been developed to reduce electromagnetic interference (EMI) for electronic devices in recent years. In this study, Fe-Si-B-Nb-Cu base amorphous strip was pulverized using a jet mill and an attritor and heat-treated to get flake-shaped nanocrystalline powders, and then the powders were mixed, cast and dried with dielectric $Al_{2}O_{3}$ powders and binders. As a result, the addition of $Al_{2}O_{3}$ powders improved the absorbing properties of the sheets noticeably compared with those of the sheets without dielectric materials. The sheet mixed with 2 wt% $Al_{2}O_{3}$ powder showed the best electromagnetic wave absorption, which was caused by the increase of the permittivity and the electric resistance due to the dielectric materials finely dispersed on the Fe-based powder.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.1
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• pp.89-94
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• 2007

High duality BiSrCaCuO thin films fabricated by using the i-beam sputtering method at various substrate temperatures, $T_{sub}$ and oxidation gas pressures, $pO_3$. The correlation diagrams of the BiSrCaCuO phases with Tsub and $pO_3$ are established in the 2212 and 2223 compositional films. In spite of 2212 compositional sputtering, Bi2201 and Bi2223 as well as Bi2212 phases come out as stable phases depending on $T_{sub}$ and $pO_3$. From these results, the thermodynamic evaluation of ${\Delta}H$ and${\Delta}S$, which are related with Gibbs' free energy change for single Bi2212 or Bi2223 phase, was performed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.6
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• pp.407-411
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• 2000

Low-temperature solder glass for use in electronic package was experimentally prepared and its crystallization behavior was investigated using differential thermal analysis (DTA) under nonisothermal condition. The composition of the solder glass was determined from PbO-ZnO-$B_2$$O_3$-$TiO_2$ glasses containing small amounts of CaO, $SiO_2$$A1_2$$O_3$ and $P_2$$O_5$. The crystallization exotherm corresponding to the formation of lead titanate (PbTiO$_3$) was observed. The crystallization of $PbTiO_3$was a three-dimensional process with the average activation energy of 223$\pm$3 kJ/mol for the crystallization from the glass matrix.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.420-423
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• 2003

[ $TiO_2$ ] thin films were fabricated by DC magnetron sputtering system at by controlling deposition times, ratios of $Ar:O_2$ partial presser ratio and substrate conditions. And the surface, cross-section morphology, microstructure, and composition ratio of the films were analyzed by FE-SEM, TEM and XPS. Besides, the optical absorption and transmittance of the $TiO_2$ films were measured by a UV-VIS-NIR Spectrophotometer, and photocatalytic properties were studied by G C Analyzer & Data Analysis system. As the result, when $TiO_2$ thin film was made at deposition time of 120[min] and $Ar:O_2$ ratio of 60:40, the best structural and optical properties among many thin films could be accepted. The best results of properties were as follows: thickness; $360{\sim}370[nm]$, grain size; 40[m], gap between two peak binding energy, $5.8{\pm}0.05[eV]$ ($2p_{3/2}$ peak and $2p_{1/2}$ peak of Ti was show at $458.3{\pm}0.05[eV]$ and $464.1{\pm}0.05[eV]$ respectively), binding energy; $530{\pm}0.05\;[eV]$, opticalenergy band gap; 3.4[eV].

• Electronics and Telecommunications Trends
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• v.36 no.3
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• pp.41-52
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• 2021

Recently, LNOI photonics technology has attracted attention as a photonics platform capable of integrating ultra-high-speed, low power consumption, and high nonlinearity optical devices, as it is possible to manufacture LiNbO₃ optical waveguides with ultra-low optical loss and a radius of curvature of several tens of micrometers. Here, we will briefly compare various photonics platforms, such as Si, InP, SiN, and LNOI, describe the current research trends of LNOI photonics, and discuss the direction of photonics technology at the conclusion.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1705-1707
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• 1997

In this work, a possible new PD de technique, based on the electro-optic effect(P effect), has been proposed. The refractive index ellipsoid of EO crystal, as $LiNbO_3$, is changed by both the externally a electric field and its hysteresis loop of which effect on this hysteresis loop gives rise t discrepancy of index variation. Therefore, an eq regarding the phase variation of modulated beam through $LiNbO_3$ crystal under applied e field, is newly proposed considering the influen hysteresis characteristics. For this purpose generated from needle-plane electrode in oil has detected by use of $LiNbO_3$ cell and analyzed b equation. As a result, it is observed that PD measu phase intervals are limited by the cr characteristics such as asymmertrical P-E hyst and half-wave voltage.

• Proceedings of the Korean Vacuum Society Conference
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• 2004.08a
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• pp.200-200
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• 2004

• Progress in Superconductivity and Cryogenics
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• v.13 no.1
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• pp.6-11
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• 2011

The $BaHfO_3$ (BHO) buffer layer on the IBAD MgO template was turned to be effective for a successful fabrication of $GdBa_2Cu_3O_{7-{\delta}}$ (GdBCO) films with high critical current density ($J_c$). Both the BHO buffer layers and GdBCO films were prepared by pulsed laser deposition (PLD). The effects of the PLD conditions, including substrate temperature ($T_s$), oxygen partial pressure ($PO_2$), and deposition time on the in-plane texture, surface roughness, and microstructures of the BHO buffer layers on the IBAD MgO template were systematically studied for processing optimization. The c-axis oriented growth of BHO layers was insensitive to the deposition temperature and the film thickness, while the in-plane texture and surface roughness of those were improved with increasing $T_s$ from 700 to $800^{\circ}C$. On the optimally processed BHO buffer layer, the highest $J_c$ value (77 K, self-field) of 3.68 $MA/cm^2$ could be obtained from GdBCO film deposited at $780^{\circ}C$, representing that BHO is a strong candidate for the buffer layer on the IBAD MgO template.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2002.11b
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• pp.68-68
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• 2002

아열대성 식물 4종 (문주란, Crinum asiaticum var. japonicum; 박달목서, Osmanthus insularis; 죽절초, Chloranthus glaber; 파초일엽, Asplenium antiquum)을 대상으로 자연 환경요인의 변화에 따른 엽록소형광을 분석하여 이들 식물의 활력도를 검토하였다. 여름철 일변화에 있어서 양지에 자라는 문주란과 박달목서는 Fv/Fm이 새벽과 밤에는 0.80~0.83 범위의 높은 값을 보이지만, 낮시간에는 0.65~0.73으로 낮았다. 1-qN과 1-qP도 낮시간에 크게 낮아졌다. 음지에 자라는 죽절초와 파초일엽의 Fv/Fm은 높아서 0.83~0.85 범위를 유지하였으며 일변화적 특성은 관찰되지 않았다. 1-qP의 변화는 거의 관찰되지 않았으나 1-qN이 낮시간에 다소 감소하는 경향을 보여주었다. 죽절초와 파초일엽에서는 광억제가 거의 일어나지 않으나 문주란과 박달목서에서는 낮시간의 고광에 의한 광억제가 나타난다. 하지만 여기에너지의 일부를 열의 형태로 방출하여 광피해를 완화시키고 있는 것으로 보인다. 겨울철에는 Fv/Fm이 모든 종에서 0.8 이하의 값을 나타내었는데, 특히 문주란의 Fv/Fm 값은 다른 3종 보다 더 낮았다. 그리고 모든 종에서 일변화적인 특성은 관찰되지 않았다. 문주란의 1-qN은 낮시간에 다소 감소하였지만, 나머지 3종의 식물은 높은 값을 나타내었다. 그리고 l-qP는 문주란과 박달목서에서는 낮시간에 0.6 범위로 낮아졌다. 이는 종에 따라 차이가 있지만 겨울철 저온의 영향을 받은 결과로 보인다. 한편, 여름철 문주란과 박달목서의 O-J-I-P곡선은 거의 유사하며 낮에 뚜렷하게 낮았고, 죽절초와 파초일엽에서는 일변화적 특성은 두드러지지 않았다. 그리고 P $I_{NO}$ 와 SF $I_{NO}$ 가 죽절초를 제외한 3종에서 여름철 낮시간에 증가하였다. 겨울철의 O-J-I-P곡선은 모든 종에서 낮시간에 다소 낮아지지만 큰 변화는 없었다. 그리고, 문주란, 박달목서, 파초일엽에서 $\psi$o/(1-$\psi$o)가 낮시간에 다소 증가하였다. 이로부터 P $I_{NO}$ , SF $I_{NO}$ , $\psi$o/(1-$\psi$o)등의 변수는 식물의 활력도를 검정하는 지표로 활용될 가능성이 높다고 할 수 있다.

• Bulletin of the Korean Chemical Society
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• v.30 no.1
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• pp.201-204
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• 2009

$BaTiO_3/SrTiO_3$ and $PbTiO_3/PbZrO_3$ superlattice thin films were fabricated on $Pt/Ti/SiO_2/Si$ substrate by the pulsed laser deposition process. The morphologies and physical properties of deposited films were characterized by using X-ray diffractometer, HR-SEM, and Impedance Analyzer. XRD data and SEM images of the films indicate that each layer was well deposited alternatively in the superlattice structure. The dielectric constant of $BaTiO_3/SrTiO_3$ superlattice thin film was higher than that of individual $BaTiO_3$ or $SrTiO_3$ film. Same result was obtained in the $PbTiO_3/PbZrO_3$system. The dielectric constant of a superlattice film was getting higher as the number of layer is increased.