• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.3
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• pp.220-226
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• 2000

The piezoelectric material for piezoelectric transformer needs the high electromechanical coupling factor( $k_{p}$) the piezoelectric constant( $d_{33}$) and the mechanical quality factor( $Q_{m}$)in order to obtain high voltage step-up ratio and low temperature rising. In this study the piezoelectric transformers were fabricated using Pb［$Zr_{0.45}$/ $Ti_{0}$48//L $u_{0.02}$(M $n_{1}$3//S $b_{2}$3/)$_{0.05}$］ $O_3$(PMS-PZT) and Pb［Z $r_{0.25}$/ $Ti_{0.375}$(M $g_{1}$3//N $b_{2}$3/)$_{0.375}$］ $O_3$+0.5wt%Mn $O_2$(PMN-PZT) ceramics. The piezoelectric properties of PMS-PZT and PMN-PZT were measured. The voltage set-up ratios of the piezoelectric transformers using PMS-PZT and PMN-PZT were the value of 15, 20 respectively under 100$_{KΩ}$ in Rosen type transformer.r.ormer.r.r.r.r.r.r.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.213-218
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• 1996

가압 경수로의 노심설계에 있어서 제한된 우라늄 자원의 효율적인 이용을 위한 다양한 방안으로 장주기 운전, 고 방출연소도 및 저누출 장전모형 등을 강구하고 있는 추세이다. 이러한 노심들은 원자로 운전주기 전반에 걸친 공간적 출력 분포 제어와 잉여반응도 제어를 위해 가연성 흡수봉을 사용하고 있으며 이와 관련 하여 가연성 흡수봉에 대한 전략등이 다 각도로 검토되고 있으며 다양한 노심에 대한 최적의 가연성 흡수봉 혹은 그 전략에 대해 많은 연구가 진행되고 있다. 본 연구에서는 웨스팅하우스형 3-Loop 발전소에 대해, 장주기 (18 개월-480 EFPD), 저누출 장전 모형 전략을 채용하여, Er$_2$O$_3$, Gd$_2$O$_3$, ZrB$_2$의 일체형 가연성 흡수봉에 대한 노심특성 및 경제성을 평형노심개념을 적용, KNFC가 노심설계에 사용하고 있는 APA(ALPHA/PHOENIX-P/ANC) 8.0.0 코드 체계를 이용하여 평가하였다. 노심특성에 대해서는 감속재 온도계수, 첨두출력인자, 잔존흡수봉효과 및 노심 연소거동에 대한 평가가 수행되었고, 동일한 주기길이(480 EFPD) 에 대한 우라늄 적재량에 대해 원광비, 변환비, 농축비, 가공비 그리고 이자율 등을 고려하여 핵주기 경제성 평가 코드인 POCO 코드를 이용하여 경제성을 평가하였다.

• Analytical Science and Technology
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• v.9 no.4
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• pp.382-391
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• 1996

In this study, 12 different chemical species of fine ceramic($BaTiO_3$) were synthesized as the standard materials for the fast and accurate measurements of X-ray fluorescence spectrometry. Samples were diluted to sixteen times with the filling compound ($Li_2B_4O_7+LiBO_2$) in order to remove the matrix effect, and to get the convenient storage and homogeneity of ingredients. The matrix effects among the ingredients were corrected by the empirical coefficient method based on the Lucas-Tooth and Price model. The standard curve on 12 standard materials containing 15 elements were obtained by using X-ray fluorescence spectrometry at three different laboratories. The correlation factors of BaO, PbO, SrO, $Fe_2O_3$, $La_2O_3$, $SnO_2$, ZnO, $ZrO_2$, CaO indicated the relati vely good agreement over 0.995 among the three different laboratories. $SiO_2$ and $Al_2O_3$ showed the poor linearity because of their low fluorescence intensities.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.3
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• pp.9-17
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• 2011

Nano-composite solders have been studied to improve the properties of Pb-free solder joints. The nanoparticles in the composite solders were carbon nanotubes(CNTs), metals (Ag, Ni, Cr, etc.), ceramics (SiC, $ZrO_2$, $TiB_2$, etc.). To fabricate the nano-composite solders, mechanical mixing methods and in-situ fabrication method has been used for well-dispersed nano phase. The characteristic properties of the nano-composite solders were high creep resistance, low undercooling, low IMC growth rate and fine microstructures. More researches on the nano-composite solders are required to improve the processibility and the reliability of the nano-composite solder joints.

• Electrical & Electronic Materials
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• v.9 no.2
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• pp.159-164
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• 1996

The development of an insulated coating which can be used for amorphous alloys is extremely important from the practical point of view. This importance may be enhanced by the influence of the coating on the magnetic properties. The purpose of this study is to show how new developed insulating coating materials and method influence the magnetic properties of amorphous Fe/sub 87/Zr/sub 7/B/sub 5/Ag/sub 1/(at%) ribbon.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.2
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• pp.95-102
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• 1994

Aluminum sheet application to automobile body panels has now become an important objective to meet the requirements of automobile weight reduction. As the Mg content in Al-Mg based alloys increased up to 7.19%, the strength and elongation increased. For instance. Al-7.19Mg alloy had a high strength of 305MPa and a high elongation of 35%. A study was also made to investigate the interrelation between grain size and tensile properties with varying the contents of Mg, Ti and Zr elements and annealing conditions. The yield stress decreased as the grain size increased, which increased the uniform elongation. The strain hardening exponents n increased as the Mg content increased, which depended on the increasing difficulties of the cross slip of dislocation.

• Transactions of the Korean hydrogen and new energy society
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• v.8 no.3
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• pp.101-109
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• 1997

We propose a new concept of hydrogen absorbing alloy, "Laves phase related BCC solid solution". It was firstly found among the phases tormed in multicomponent nominal $AB_2$ alloys which consisted of Zr and Ti for the A metal site and 5A, 6A and 7A transition metals for the B metal sites. In these alloys a BCC solid solution often coexisted with a Laves phase. It showed stability of hydrides and reaction kinetics almost identical to intermetallics such as Laves phase alloys. We prepared an almost pure "Laves phase related BCC solid solution" and found that it had a large hydrogen capacity (more than 2 mass%) and fast hydrogen absorption and desorption kinetics at ambient temperature and pressure. This new hydrogen absorbing alloy may open a new era of hydrogen related application such as hydrogen vehicles.

• Journal of Magnetics
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• v.9 no.2
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• pp.65-68
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• 2004

Magnetically soft nanomaterials obtained by controlled crystallisation of metallic glasses are the newest group of materials for inductive components. In particular, research is carried out in the field of alloys for high temperature applications. This kind of materials must meet two basic requirements: good magnetic properties and stability of properties and structure. In the present work the magnetic properties and structure of Fe-Co-Hf-Zr-Cu-B (HIDTPERM-type) alloys were investigated, as well as their stability. Differential thermal analysis, (DTA), X-ray diffractometry (XRD), transmission electron microscopy (TEM), magnetometry (VSM) and quasistatic hysteresis loop recording were used to characterise structure and properties of the alloys investigated. Optimisation against properties and their stability was performed, resulting in formulation of chemical composition of the optimum alloy, as well as its heat treatment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.594-597
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• 2003

In the present study, the piezoelectricity and polarization of multilayer ceramic actuator, being designed to stack PMN-PZ-PT ceramic layers and Ag-Pd electrode layers alternatively, were investigated under a consideration of geometric factor, the volume ratio of the ceramic to the electrode layers. The actuators were fabricated by tape casting of 0.2Pb(Mg1/3Nb2/3)O3-0.38PbZrO3-0.42PbTiO3 followed by lamination and burnout & co-firing processes. The actuators of 10 10 0.62 nm3 in size were formed in a way that 60 200 m thick ceramics were stacked alternatively with 5 m thick electrode layer. Increases in polarization and electric field-induced displacement with thickness of the ceramic layer were attributed to change of 90o/180o domain ratio, which was affected by interlayer internal stress. The piezoelectricity and actuation behaviors were found to depend upon the volume ratio (or thickness ratio) of ceramic to electrode layers.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.178.2-178.2
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• 2013

Conventional ultraviolets A,B,C are known to be very important factor of killing, changing surface properties of biological cells and materials. It is of great importance to investigate the influence of extreme ultraviolet (EUV) exposure on the biological cell. Here we have studied high density EUV plasma and its emission characteristics, which have been generated by plasma focus device with hypercycloidal pinch (HCP) electrode under various Ar gas pressures ranged from 30~500 mTorr in this experiment. We have also measured the plasma characteristics generated from the HCP plasma focus device such as electron temperature by the Boltzman plot, plasma density by the Stark broading method, discharge images by open-shuttered pin hole camera, and EUV emission signals by using the photodiode AXUV-100 Zr/C.