• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.212-212
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• 2014

이트리아 안정화 지그코니아(Yttria-stabilized zirconia, YSZ)는 이트리아의 첨가에 의해 지르코니아에 생성된 산소 빈자리(oxygen vacancy)로 $O^{2-}$ 이온이 전도성을 가지게 되는 특징이 알려지면서 최근 고체산화물 연료전지연구에서 많은 관심을 받고 있다.[1] YSZ를 기반으로한 고체산화물 연료전지의 특성을 개선하기 위해서는 YSZ 내에서의 산소교환 메카니즘을 이해하는 것이 매우 중요하다. 본 연구에서는 $^{18}O2$ 추적 기체(tracer gas) 이용하여 확산된 YSZ박막에서의 산소 확산 거동을 초미세이차이온질량분석기(Nano Secondary Ion Mass Spectrometry, Nano SIMS)를 이용하여 조사하였다. Nano SIMS는 작은 입사 이온빔의 크기를 구현할 수 있고, 다중검출기를 이용하여 높은 질량분해능으로 간섭없이 산소동위원소를 동시에 모두 검출할 수 있는 장점이 있다. 본 발표에서는 Nano SIMS를 이용한 YSZ박막에서의 산소 거동 평가 결과를 상세하게 보일 것이다.

• Journal of the Korean Magnetics Society
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• v.19 no.3
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• pp.113-119
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• 2009

$^{57}Fe_xCu_{1-x}O$(x = 0.0, 0.02) powders were prepared by sol-gel method and their crystallographic and magnetic hyperfine properties have been studied using X-ray diffraction and $M{\ddot{o}}ssbauer$ spectroscopy (MS). The crystal structure of the samples is found to be monoclinic without any secondary phases and their lattice parameters increase with increasing annealing temperature ($T_A$), which is attributed to an increase in oxygen-vacancy content. MS measurements at room temperature indicate that $Fe^{3+}$ ions substitute $Cu^{2+}$ sites and ferromagnetic phase grow with increasing $T_A$. Magnetic hyperfine and quadrupole interactions of $^{57}Fe_{0.02}Cu_{0.98}O$ ($T_A=500^{\circ}C$) in the antiferromagnetic state at 17 K have been studied, yielding the following results: $H_{hf}=426.94\;kOe$, ${\Delta}E_Q=-3.67\;mm/s$, I.S.=0.32 mm/s, ${\theta}=65^{\circ}$, ${\phi}=0^{\circ}$, and ${\eta}=0.6$.

• Korean Journal of Materials Research
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• v.33 no.4
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• pp.135-141
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• 2023

The volatilization of alkali ions in (K,Na)NbO₃ (KNN) ceramics was inhibited by doping them with alkaline earth metal ions. In addition, the grain growth behavior changed significantly as the sintering duration (t_s) increased. At 1,100 ℃, the volatilization of alkali ions in KNN ceramics was more suppressed when doped with alkaline earth metal ions with smaller ionic size. A Ca²⁺-doped KNN specimen with the least alkali ion volatilization exhibited a microstructure in which grain growth was completely suppressed, even under long-term sintering for t_s = 30 h. The grain growth in Sr²⁺-doped and Ba²⁺-doped KNN specimens was suppressed until t_s = 10 h. However, at t_s = 30 h, a heterogeneous microstructure with abnormal grains and small-sized matrix grains was observed. The size and number of abnormal grains and size distribution of matrix grains were considerably different between the Sr²⁺-doped and Ba²⁺-doped specimens. This microstructural diversity in KNN ceramics could be explained in terms of the crystal growth driving force required for two-dimensional nucleation, which was directly related to the number of vacancies in the material.

• Advances in materials Research
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• v.1 no.2
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• pp.109-113
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• 2012

Electromigration-induced void evolutions in typical upper and lower layer dual-inlaid Copper (Cu) interconnect structures were simulated by applying a phenomenological model resorting to Monte Carlo based simulations, which considers redistribution of heterogeneously nucleated voids and/or pre-existing vacancy clusters at the Copper/dielectric cap interface during electromigration. The results indicate that this model can qualitatively explain the electromigration-induced void evolutions observations in many studies reported by several researchers heretofore. These findings warrant need to re-investigate technologically important electromigration mechanisms by developing rigorous models based on similar concepts.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.142-142
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• 2009

Bismuth-substituted yttrium iron garnet(Bi-YIG; $Bi_xY_{3-x}Fe_5O_{12}$, x=0, 0.5, 1.0, 1.5, 2.0) thin films were fabricated on glass substrates using a metal organic decomposition (MOD) method. The dielectric property was measured by NSMM(Near-field scanning microwave microscopy) system that operating frequency is 4 Ghz. The obtained reflection coefficient $S_{11}$ of the Bi:YIG thin films with different bismuth concentration was increased as the bismuth concentration increased due to the lattice mismatch and vacancy of ions because of a lager ionic radius of bismuth ion than yttrium ion.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.212.2-212.2
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• 2015

본 연구에서는 용액 공정을 통해 제작한 IGZO, ITZO 박막 트랜지스터의 전기적 특성을 비교, 분석하였다. 실험에 사용된 용액의 농도는 In:Zn:Ga, In:Zn:Sn = 1:1:1로 제작하여 Spin-Coating을 통해 증착하였다. 두 소자 모두 $350^{\circ}C$에서 열처리 공정을 진행한 뒤, 전기적 특성을 측정 및 분석하였다. IGZO 박막 트랜지스터의 경우, Threshold Voltage, S.Swing, Mobility, On/Off ratio가 각각 2.2 V, 0.42, $0.18cm^2/Vs$, $1.5{\times}$10^5로 측정되었으나 ITZO 박막 트랜지스터의 경우, -6.92 V, 0.91, $0.43cm^2/Vs$, $2.1{\times}$10^5 로 IGZO보다 Negative한 방향으로 이동하였다. 이는 Sn이 Ga에 비해 Band gap이 넓고, 산소와의 결합력이 작기 때문에, ITZO 박막 트랜지스터가 Oxygen vacancy형성을 통한 Carrier density가 높은 것으로 판단된다.

• Transactions of Materials Processing
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• v.14 no.4 s.76
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• pp.319-326
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• 2005

In this study, the nano-deformation behavior of semi-solid Al-Si alloy was investigated using a molecular dynamics simulation as a part of the research on the surface crack behavior in thixoformed automobile parts. The microstructure of the grain-size controlled Al-Si alloy consists of primary and eutectic regions. In eutectic regions the crack initiation begins with initial fracture of the eutectic silicon particles and inside other intermetallic phases. Nano-deformation characteristics in the eutectic and primary phase of the grain-size controlled Al-Si alloy were investigated through the molecular dynamics simulation. The primary phase was assumed to be single crystal aluminum. It was shown that the vacancy occurred at the zone where silicon molecules were.

• 전기의세계
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• v.17 no.2
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• pp.16-26
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• 1968

Cds is possible to add excess donors and to compensate partially using other group metals as acceptors. The impurities can ble incorporated either during crysta growth or by diffusion into a bulkcrystal. The addition of rimpurities leads also to the production of vacancies in a manner depending on the atmosphere surrounding the crystal during growth, during the diffusion process or using bulk. Cds of the mentioned above affects spectral sensitivity, speed of response, the variation on photocurrent, electron life time, and decay of photoconductivity with temperature and with intensity of illumination. In the work to be deseribed, these properties have been studied between liquid nitrogen and room temperature. In addition, the electron trap distribution has been correlated with speed of response, variation of photocurrent with temperature in various atmosphere. Four major trapping levels have been observed, and their identification with impurity and vacancy levels is discussed. And also the effects of lattice imperfections on the photoconductive properties CdS were investigated in detail.

• The Journal of Information Technology
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• v.6 no.3
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• pp.53-64
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• 2003

The purpose of this study is to examine the valuation models and valuation factors for the valuation of real estates. In Korea, the weak market conditions prevented investors from the sound investing the real estates. To develop the real estate investment market, we need the information of sale prices, volume, vacancy rates, and regulatory policies to the various types, and areas of the real estates. In addition, we have to develop the indirect investing methods such as REITs.

• Journal of the Korean Society for Heat Treatment
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• v.5 no.4
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• pp.233-239
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• 1992

A study of the precipitation process of Al-Li binary alloy at low ageing temperature has been carried by electrical resistivity measurement. Two types of G.P.zones were formed during ageing at low temperature. G.P. (1) zone and G.P. (2) zone have been formed primarily at ageing temperature below $60^{\circ}C$ and at ageing temperature range of $80^{\circ}C$ to $100^{\circ}C$, respectively. Therefore the precipitation process of Al-Li binary alloy was as follows; G.P.(1) zone ${\rightarrow}$ G.P.(2) zone ${\rightarrow}{\delta}^{\prime}{\rightarrow}{\delta}$ G.P. (1) zone might be affected by excess vacancies, but G.P. (2) zone might be affected by secondary defects. clusters and Li-vacancy pairs. The activation energy for formation of G.P. (2) zone is 0.87eV. It is lower than that of Al-Cu alloy.