• Journal of Sensor Science and Technology
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• v.16 no.2
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• pp.120-125
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• 2007

The effect of $MnO_{2}$ as a sintering additive on the microstructures and the piezoelectric properties, especially mechanical quality factor, of 0.05 Pb$(Sb_{0.5}Nb_{0.5})O_{3}$-0.95 Pb$(Zr_{0.52}Ti_{0.48})O_{3}$ (PSN-PZT) piezoelectric ceramics was investigated. The samples were sintered at $1250^{\circ}C$ for 2 h. The crystal structure and surface morphology of the sample were examined using XRD and FE-SEM, respectively. A study on the influence of $MnO_{2}$ additives on the dielectric and piezoelectric properties showed that the $MnO_{2}$-added PSN-PZT system exhibited a high mechanical quality factor and well-situated piezoelectric properties. The optimized results of $d_{33}$ (319 pC/N), $k_{p}$ (55 %), and $Q_{m}$ (751.24) were obtained at 0.2 wt% $MnO_{2}$ added PSN-PZT piezoelectrics.

• Journal of Sensor Science and Technology
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• v.17 no.2
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• pp.127-132
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• 2008

The effect of $CeO_2$ as a sintering additive on the microstructure and the piezoelectric property of yPb$(Sb_{0.5}Nb_{0.5})O_3$-(1-y)Pb$(Zr_{0.52}Ti_{0.48})O_3$ ($0{\leq}y{\leq}0.1$, PSN-PZT) for a hypersonic sound speaker (HSS) application was investigated. The samples were sintered at $1250^{\circ}C$ for 2 h. The crystal structure and surface morphology of the samples were examined using XRD and FE-SEM, respectively. Study on the influence of $CeO_2$ additives on the dielectric and piezoelectric properties indicated that the $CeO_2$-added PSN-PZT system had a high piezoelectric properties. The optimized results of ${\varepsilon}_r=1209$, $K_p$=52% $d_{33}$=351(pC/N) and $Q_m$=1230.16 were obtained at 0.4 wt.% $CeO_2$-added PSN-PZT.

• Journal of the Korean Solar Energy Society
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• v.23 no.1
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• pp.1-8
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• 2003

Various efforts to combine new high-tech materials with solar system have been progressed nowadays in order to improve the performance of the existing passive solar system. TIM(Transparent Insulation Material) replacing the conventional outer building envelope glazing as well as the wall is good example for this trend. TI integrated wall is a thermal mass wall with a special shaped TIM instead of using typical envelope materials The tested TIM type is a small(diameter 4mm and thickness 50mm) capillary tube of Okalux model and cement brick(density 1500kg/m3). The purpose of this study was to analyze the thermal performance through the actual measurements performed in a test cell. This study was carried out to justify the following issues. 1) the impact of Tl-wall over the temperature variations 2) the impact of mass wall surface absorptance over the transient thermal behavior and 3) the impact of thermal mass wall thickness over the temperature variations. Finally, as results indicated that the peak time of room temperature was shifted about one hour early when absorptance of thermal mass wall changed from 60% to 95% for the 190mm thickness thermal mass wall test case. the temperature difference of both surfaces of thermal mass wall surface showed about $23^{\circ}C$ during a day of March for the 380mm thickness thermal mass wall case. However, the thermal mass wall was over-heated by outside temperature and solar radiation in a day of May the temperature difference of both surfaces of thermal mass wall surface was indicated $10^{\circ}C$ and inside temperature was observed more than average 22C.

• Korean Journal of Materials Research
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• v.20 no.9
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• pp.483-487
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• 2010

To fabricate $TiO_2$ nanoparticle-based dye sensitized solar cells (DSSCs) at a low-temperature, DSSCs were fabricated using hydropolymer and ZnO nanoparticles composites for the electron transport layer around a low-temperature ($200^{\circ}C$). ZnO nanoparticle with 20 nm and 60 nm diameter were used and Pt was deposited as a counter electrode on ITO/glass using an RF magnetron sputtering. We investigate the effect of ZnO nanoparticle concentration in hydropolymer and ZnO nanoparticle solution on the photoconversion performance of the low temperature fabricated ($200^{\circ}C$) DSSCs. Using cis-bis(isothiocyanato)bis(2,20 bipyridy1-4,40 dicarboxylato) ruthenium (II) bis-tetrabutylammonium (N719) dye as a sensitizer, the corresponding device performance and photo-physical characteristics are investigated through conventional physical characterization techniques. The effect of thickness of the ZnO photoelectrode and the morphology of the ZnO nanoparticles with the variations of hydropolymer to ZnO ratio on the photoconversion performance are also investigated. The morphology of the ZnO layer after sintering was examined using a field emission scanning electron microscope (FE-SEM). 60 nm ZnO nanoparticle DSSCs showed an incident photon-to-current conversion efficiency (IPCE) value of about 7% higher than that of 20 nm ZnO nanoparticle DSSCs. The maximum parameters of the short circuit current density ($J_{sc}$), the open circuit potential ($V_{oc}$), fill factor (ff), and efficiency ($\eta$) in the 60 nm ZnO nanoparticle-based DSSC devices were 4.93 mA/$cm^2$, 0.56V, 0.40, and 1.12%, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.193-197
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• 2004

The organic light emitting diode (OLED) is proposed as the novel source in the microchip because it has ideal merits (various wavelengths, thin-film structure and overall emitting) for the integration. In this paper, we fabricated the finger-type pin photodiodes for fluorescence detection and the advanced microchip with OLED integrated pn the microchannel. The finger-type in the diode design extended the depletion region and reduced the internal resistance about 31.2% than rectangular-type. The photodiodes had a 100pA leakage current and a 8720 sensitivity $(I_{Light}/I_{Dark})$ at -1 V bias. The interference filter with 32 layers ($SiO_2$, $TiO_2$) was directly deposited on the photodiode. The OLED was fabricated on the ITO coated glass and was bonded with LOC. The application of thin-film OLED increased the excitation efficiency and simplified the integration process extremely. The prototype device of this application had a superior sensitivity of 100nM-LOD in the fluorescence detection.

• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.687-693
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• 2004

Composite membranes with a titania layer were prepared by soaking-rolling method with the titania sol of nanoparticles formed in the sol-gel process and investigated regarding the vapor permeation of various organic mixtures. The support modification was conducted by pressing $SiO_2$ xerogel of 500 nm in particle size under 10 MPa on the surface of a porous stainless steel (SUS) substrate and designed the multi-layered structure by coating the intermediate layer of ${\gamma}-Al_2O_3$. Microstructure of titania membrane was affected by heat-treatment and synthesis conditions of precursor sol, and titania formed at calcination temperature of 300$^{\circ}C$ with sol of [$H^+$]/[TIP]=0.3 possessed surface area of 210 $m^2$/g, average pore size of 1.25 nm. The titania composite membrane showed high $H_2/N_2$ selectivity and water/ethanol selectivity as 25-30 and 50-100, respectively. As a result of vapor permeation for water-alcohol and alcohol-alcohol mixture, titania composite membrane showed water-permselective and molecular-sieve permeation behavior. However, water/methanol selectivity of the membrane was very low because of chemical affinity of permeants for the membrane by similar physicochemical properties of water and methanol.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.7
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• pp.937-942
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• 2009

The aim of this study was to analyze the effects on growth and muscle development during the growing period of the sex-linked dwarf gene in the background of a Taiwan Country chicken strain, L2, selected for egg production. Eight crossbred males, heterozygous for the DW*DW mutation, were each backcrossed to six females of the L2 strain to produce two genotypes of BC females, either normal (DW*N+/-) or dwarf (DW*DW/-). The experiment included 251 normal and 207 dwarf pullets. The effect of the dwarf gene on body weight and shank length was highly significant from 2 weeks of age. The reduction of body weight by the dwarf gene reached 34.8% and 37.4% as compared to normal sibs at 16 and 20 weeks of age, respectively. Parameters of the growth curve were estimated: the age at inflection (TI) was higher in normal pullets (66.9 days) than in dwarf pullets (61.2 days). A significant effect of the dwarf gene on single muscle fiber cross-section area was found from 12 weeks of age onwards, whereas the dwarf gene had no effect on the total number of muscle fibers. Comparing the effect of the dwarf gene on shank length at different ages revealed an earlier effect on skeleton growth, observed from 2 weeks of age, than on muscle development, which was affected from 8 to 12 weeks of age.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.403-404
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• 2013

최근 scaling down의 한계에 부딪힌 DRAM과 Flash Memory를 대체하기 위한 차세대 메모리(Next Generation Memory)에 대한 연구가 활발히 진행되고 있다. ITRS (international technology roadmap for semiconductors)에 따르면 PRAM (phase change RAM), RRAM (resistive RAM), STT-MRAM (spin transfer torque magnetic RAM) 등이 차세대 메모리로써 부상하고 있다. 그 중 RRAM은 간단한 구조로 인한 고집적화, 빠른 program/erase 속도 (100~10 ns), 낮은 동작 전압 등의 장점을 갖고 있어 다른 차세대 메모리 중에서도 높은 평가를 받고 있다 [1]. 현재 RRAM은 주로 금속-산화물계(Metal-Oxide) 저항 변화 물질을 기반으로 연구가 활발하게 진행되고 있다. 하지만 근본적으로 공정 과정에서 산소에 의한 오염으로 인해 수율이 낮은 문제를 갖고 있으며, Endurance 및 Retention 등의 신뢰성이 떨어지는 단점이 있다. 따라서, 본 연구진은 산소 오염에 의한 신뢰성 문제를 근본적으로 해결할 수 있는 다양한 금속-질화물(Metal-Nitride) 기반의 저항 변화 물질을 제안해 연구를 진행하고 있으며, 우수한 열적 안정성($>450^{\circ}C$, 높은 종횡비, Cu 확산 방지 역할, 높은 공정 호환성 [2] 등의 장점을 가진 WN 박막을 저항 변화 물질로 사용하여 저항 변화 메모리를 구현하기 위한 연구를 진행하였다. WN 박막은 RF magnetron sputtering 방법을 사용하여 Ar/$N_2$ 가스를 20/30 sccm, 동작 압력 20 mTorr 조건에서 120 nm 의 두께로 증착하였고, E-beam Evaporation 방법을 통하여 Ti 상부 전극을 100 nm 증착하였다. I-V 실험결과, WN 기반의 RRAM은 양전압에서 SET 동작이 일어나며, 음전압에서 RESET 동작을 하는 bipolar 스위칭 특성을 보였으며, 읽기 전압 0.1 V에서 ~1 order의 저항비를 확보하였다. 신뢰성 분석 결과, $10^3$번의 Endurance 특성 및 $10^5$초의 긴 Retention time을 확보할 수 있었다. 또한, 고저항 상태에서는 Space-charge-limited Conduction, 저저항 상태에서는 Ohmic Conduction의 전도 특성을 보임에 따라 저항 변화 메카니즘이 filamentary conduction model로 확인되었다 [3]. 본 연구에서 개발한 WN 기반의 RRAM은 우수한 저항 변화 특성과 함께 높은 재료적 안정성, 그리고 기존 반도체 공정 호환성이 매우 높은 강점을 갖고 있어 핵심적인 차세대 메모리가 될 것으로 기대된다.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.5
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• pp.508-516
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• 1992

In this study, dielectric and piezoelectric properties of 0.05Pb(AlS12/3TWS11/3T)OS13T-0.95Pb(ZrS10.52TTiS10.48T)OS13T system ceramics were investigated with respect to the variations of MnOS12T and FeS12TOS13T additions amounts. The results obtained in this study are summarized as follows: 1. As the amounts of MnOS12T and FeS12TOS13T are increased, tetragonality(c/a) and apparent density were decreased but grain size was increased, also the limits of solubility were revealed because pores were formed at the amounts of 0.3wt% MnOS12T and 0.5wt% FeS12TOS13T. 2. AS the increasing of amounts of MnOS12T and FeS12TOS13T, the temperature of phase transition(TS1cT) was decreased, and pemeability had maximum value at the amount of 0.3wt% MnOS12T but were sharply decreasd for the increasing FeS12TOS13T amounts. 3. As the amounts of MnOS12T and FeS12TOS13T are increased, the electro-mechanical coupling factor(kS1pT) was decreased from 60% to 41%, 19% respectively, but mechanical quality factor(QS1mT) had maximum values 720 for amount of 0.3wt% MnOS12T and 320 the amount of 0.5wt% FeS12TOS13T.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.11
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• pp.902-905
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• 2012

This study is explore the photoelectric conversion change of dye-sensitized solar cells with surface treatment of the conductive substrate. gases of FTO surface treatment were $N_2$, and $O_2$. Treatment conditions of surface were gas flux from 25 sccm to 50 sccm and RF power were from 25 W to 50 W. Treatment time and pressure were fixed 5 min and 100 mtoor. The best sheet resistance and surface roughness were obtained by $O_2$ 50 sccm and 50 W and that result were 7.643 ${\Omega}/cm^2$ and 17.113 nm, respectively. The best efficiency result was obtained by $O_2$ 50 sccm and 50 W and that result of Voc, Jsc, FF and efficiency were 7.03 V, 14.88 $mA/cm^2$, 63.75% and 6.67%, respectively.