• Journal of the Korean Ceramic Society
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• v.28 no.9
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• pp.683-688
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• 1991

ZnO-P2O5 system glass containing 45 to 60 mol% ZnO has been melted at 120$0^{\circ}C$ and crystallized through heat treatment. Each condition of crystallization was determined by measurement of dilatometric softening point and DTA. The principal crystalline phase was identified as zinc metaphosphate [Zn(PO3)2] in the glasses containing 45~55 mol% ZnO and zinc pyrophosphate (Zn2P2O7) in the sample of 60 mol% ZnO with X-ray diffraction patterns. The crystalline mechanism was investigated by XRD and SEM. As the results, the specimens containing 50~60% ZnO showed the existence of oriented structure due to one-dimensional crystal growth.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.3
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• pp.177-182
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• 2010

The pentacene-based organic thin film transistors(OTFTs) using polyvinylalcohol(PVA) alignment layer were fabricated on the $SiO_2$ evaporated to n-type (111) Si substrates. The pentacene film was deposited by thermally evaporated at $10^{-7}$ torr. X-ray diffraction (XRD) and atomic force microscope(AFM) measurement showed pentacene film which deposited on rubbed PVA layers were partially crystallized at (001) plane. The pentacene OTFTs with PVA layers rubbed perpendicular to the direction of current flow was shown to align better orientation than parallel rubbed case and thus to enhance the mobility and saturation current by a factor of 2.3 respectively. We obtained mobility by 0.026 $cm^2$/Vs and on-off current ratio by ${\sim}10^8$.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.5 s.248
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• pp.602-608
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• 2006

Vehicle components such as lower control arm are usually affected by heat during the welding process. As a result, residual stress is generated, which has much effect on mechanical performances such as crashworthiness and durability. In this study, the residual stress in lower control arm has been measured by the x-ray diffraction method and been analyzed by finite element methods. Heat transfer during seam weld process has been calculated and used in calculating thermal deformation with temperature dependent material properties. High residual stress has been found at vertical wall both by measurement and simulation. The simulation also showed the residual stress re-distribution when the component is subjected to cyclic loading condition.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.2
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• pp.51-56
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• 2005

We prepared orthorhombic $LiMnO_2$ by emulsion drying method. The thermo-gravimetric measurement and X-ray diffraction studies indicated that the orthorhombic $LiMnO_2$ phase was formed above $800^{\circ}C$ by oxygen evaporation process from $LiMn_2O_4$ and $Li_2MnO_3$. In this process, we could control the ordering of $LiMnO_2$ with heating rate. It was observed that electrochemical properties depended on the ordering of this material; the ordered one exhibited good capacity retention, whereas the disordered one suffered capacity fading upon cycling, especially in the 3 V region. Transmission electron microscopic (TEM) study showed that this difference is related with difference in the stress relieving effects in the samples.

• Journal of the Korean Ceramic Society
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• v.46 no.4
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• pp.397-404
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• 2009

Using rice husk ash as silica, the influence of the firing temperature and holding time on the color intensity of Pr-$ZrSiO_4$ pigments were investigated. The Pr-yellow pigments were calcined at 500, 700, 800, 900, 950, 1000, $1100^{\circ}C$ in a ceramic method. The synthesized pigments were characterized by DT-TG thermal analysis, X-ray diffraction, UV-Vis spectroscopy, and SEMEDAX analysis. The relationship between the zircon phase-formation growth and Pr-yellow color development was evaluated and the optimum firing conditions were determined. The color of the pigment samples was characterized on the grounds of the Commission Internationale de l'Eclairage (CIE) standard procedure (CIE $L^*a^*b^*$ measurement) after an application on the bisque ceramic tile.

• Architectural research
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• v.13 no.1
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• pp.25-32
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• 2011

The purpose of this research is to investigate the effect of specific hydration reaction on the stiffening process of cement paste. The cement compositions are manipulated to cause specific hydration reactions (secondary gypsum and syngenite formation) responsible for false set, and the relationship between specific hydration reactions and the flow and stiffening behavior of cement paste were investigated using modified ASTM C 403 penetration resistance measurement and oscillatory shear rheology. X-ray powder diffraction (XRD) was used for the phase identification associated with premature stiffening of cement paste. Differential thermal analysis (DTA) and thermogravimetric analysis (TGA) were used for verification of syngenite formation. From the results, both secondary gypsum and syngenite formation caused faster stiffening and set. The amount of syngenite produced during 1 hour hydration was approximately 1 % of total mass of the cement paste, but cement paste with syngenite formation showed significantly accelerated stiffening behavior compared to normal cement paste.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.329.1-329.1
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• 2014

In this paper, we report electrical, optical and structural properties of Al-doped zinc oxide (AZO) thin films deposited at different substrate temperatures and pressures. The films were prepared by radio frequency (RF) magnetron sputtering on glass substrates in argon (Ar) ambient. The X-ray diffraction analysis showed that the AZO films deposited at room temperature (RT) and 20 Pa were mostly oriented along a-axis with preferred orientation along (100) direction. There was an improvement in resistivity ($3.7{\times}10^{-3}{\Omega}-cm$) transmittance (95%) at constant substrate temperature (RT) and working pressure (20 Pa) using the Hall-effect measurement system and UV-vis spectroscopy, respectively. Our results have promising applications in low-cost transparent electronics, such as the thin-film solar cells and thin-film transistors due to favourable deposition conditions. Furthermore our film deposition method offers a procedure for preparing highly oriented (100) AZO films.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.209.2-209.2
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• 2014

In recent years, researches about hydrophobic and hydrophilic surfaces have been executed however their other effects have not been researched enough. In this paper, the fabrication method of hierarchical structures of micro line array combined with fluorinated wax for anisotropic superomniphobic wettability is presented. We have achieved anisotropic and superomniphobic surface via simple two step methods, which are maskless photolithography and wax deposition. In order to prove how to provide those characteristics, SEM, contact angle measurement tool and X-ray diffraction are used. Fluorinated wax is crystalized self-assembly and it is subordinated on micro line array so that it is able to display anisotropic wettability. Understanding on anisotropic superomniphobic surface and simple fabrication method has been attracted to apply for lots of applications which range from self-cleaning surface, microfluidic chip, to directionally fluid control device, even in oily fluid.

• Macromolecular Research
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• v.14 no.6
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• pp.596-602
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• 2006

The effect of high-temperature spinning and poly(vinyl pyrrolidone) (PVP) additive on poly(vinylidene fluoride) (PVDF) hollow fiber membranes was investigated using differential scanning calorimetry, X-ray diffraction measurement, and scanning electron microscopy, together with the corresponding microfiltration performances such as water flux, rejection rate, and elongational strength. Using high-temperature spinning, porous hollow fiber membranes with particulate morphology were prepared through PVDF crystallization. The particulate structure of the membranes was further modified by the addition of miscible PVP with PVDF. Due to these effects, the rejection rate and strength of the fibers were increased at the expense of reduced water flux and mean pore size, which indicates that high-temperature spinning and PVP addition are vary effective to control the morphology of PVDF hollow fiber membranes for microfiltration.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.187-187
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• 2009

GAZO 박막의 증착은 $Ga_{2}O_{3}$의 첨가량 (6.65wt%) GZO 타겟과 $Al_{2}O_{3}$의 첨가량 (2.0wt%) AZO 타겟이 각각 장착된 2개의 캐소드를 이용한 DC 마그네트론 동시방전법에 의하여 non-alkali glass 기판위에 다양한 조건(파워, 기판온도, $H_2$ 참가량)에서 행하였다. GAZO박막의 전기적 특성은 Hall Effect measurements를 사용하여 측정 하였으며, 구조적 특성, 박막의 화학적 조성 및 광학적 특성은 XRD(X-ray diffraction), FESEM(Filed Emission Scanning Electron Microscope) 및 UV-Vis Spectrophotometer를 사용하여 평가 하였다. Al을 도입함으로써 캐리어밀도의 증가에 의해 GZO 박막의 특성은 개선됨을 확인 할 수 있었다.