• Title/Summary/Keyword: bonding surface

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A Study on the Shock Compaction of Ceramic Powders using Explosive (폭약을 이용한 세라믹분말의 충격고화에 관한 연구)

  • Kim, Young-Kook;Kim, See-Jo;Cho, Sang-Ho
    • Tunnel and Underground Space
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    • v.22 no.2
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    • pp.157-161
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    • 2012
  • ZnO-98% and $Ga_2O_3$-2% powder were consolidated by shock compaction technique, which uses a high performance explosive. The microstructural and electrical characteristics of $ZnOGa_2O_3$ compact with density of 97% and hardness of 220~250 $H_v$ were investigated using SEM (Scanning Electron Microscope) and X-ray diffraction analysis, respectively. In the microstructures of the compact, there were no visible cracks at most of the surface areas, and interparticle bonding between powder particles was confirmed. The broadened peaks were detected due to deformation of crystallited size and high electric resistances were confirmed due to increased grains because of shock energy with a high pressure and high velocity.

Electrical/Optical Characterization of PZT Thin Films Deposited through Sol-Gel Processing

  • Hwang, Hee-Soo;Kwon, Kyoeng-Woo;Choi, Jeong-Wan;Do, Woo-Ri;Hwang, Jin-Ha
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.08a
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    • pp.361-361
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    • 2012
  • PZT (Pb(Zr,Ti)O3) thin films have been used widely in the MEMS application, due to their inherent ferroelectric and piezoelectric properties. Such ferroelectricity induces much higher dielectric constants compared to those of the nonperovskite materials. In this work, the PZT thin films were deposited onto Indium-Tin-oxide (ITO) substrates through the spin-coating of PZT sols. The deposited PZT thin films were characterized in terms of the electrical and optical properties with special emphases on conductivity and optical constants. The detailed analysis techniques incorporate the dc-based current-voltage characteristics for the electrical properties, spectroscopic ellipsometry for optical characterization, atomic force microscopy for surface morphology, X-ray Photoelectron Spectroscopy for chemical bonding, Energy-dispersive X-ray Spectrometry for chemical analyses and X-ray diffraction for crystallinity. The ferroelectric phenomena were confirmed using capacitance-voltage measurements. The integrated physical/chemical features are attempted towards energy-oriented applications applicable to next-generation high-efficiency power generation systems.

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Etching characteristics of gold thin films using inductively coupled $Cl_2/Ar$ plasma ($Cl_2/Ar$ 유도 결합 플라즈마에 의한 gold 박막의 식각특성)

  • Chang, Yun-Seong;Kim, Dong-Pyo;Kim, Chang-Il;Chang, Eui-Goo;Lee, Su-Jae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.05b
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    • pp.7-11
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    • 2002
  • In this study, Au thin films were etched with a $Cl_2/Ar$ gas combination in an in an inductively coupled plasma. The etch properties were measured for different gas mixing ratios of $Cl_2/(Cl_2+Ar)$ while the other process conditions were fixed at rf power (700 W), dc bias voltage (150 V), and chamber pressure (15 mTorr). The highest etch rate of the Au thin film was 3500 $\AA/min$ and the selectivity of Au to $SiO_2$ was 4.38 at a $Cl_2/(Cl_2+Ar)$ gas mixing ratio of 0.2. The surface reaction of the etched Au thin films was investigated using x-ray photoelectron spectroscopy (XPS) analysis. There is Au-Cl bonding by chemical reaction between Cl and Au. During the etching of Au thin films in $Cl_2/Ar$ plasma, Au-Cl bond is formed, and these products can be removed by the physical bombardment of Ar ions. In addition, Optical emission spectroscopy (OES) were investigated to analyze radical density of Cl and Ar in plasma. The profile of etched Au investigated with scanning electron microscopy (SEM).

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Application of Art Clay Silver in Manufacturing Necklace (목걸이 제작에 있어서 Art Clay Silver활용에 관한 연구)

  • Park, Su-Jung;Koh, Je-Man;Mun, Sung
    • Archives of design research
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    • v.18 no.4 s.62
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    • pp.35-44
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    • 2005
  • In the world, most of the metal technologists were as called as adornment artists than other field of industrial arts strongly industrial characters functional materials and manufacturing technology many used in the present age. In the study, one of adornments researched and material character analyzed about Art Clay Silver. The shrinkage rate of shape was about 0.24%. A shrinking phenomenon drying time thought of evaporation of water linking bonding agents and powders. After calcination of Art Clay Silver, the EDX used that just Ag 100% analyzed a result from the surface assay in the room temperature. A binder with powder in the room temperature considered to disappear, because it was been fume and smoke at high calcined temperature. A study showed when handicrafted necklaces make by these characteristic as using in difficult and delicated operations rather than naturally and beautifully expressive products.

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The Effects of Driving Waveform for Piezoelectric Drop On Demand Industrial Inkjet Head (산업용 압전 잉크젯 헤드의 구동신호에 따른 특성)

  • Kim Young-Jae;Yoo Young-Seuck;Sim Won-Chul;Park Chang-Sung;Joung Jae-Woo;Oh Yong-Soo
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.55 no.8
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    • pp.417-422
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    • 2006
  • This paper presents the effect of driving waveform for piezoelectric bend mode inkjet printhead with optimized mechanical design. Experimental and theoretical studies on the applied driving waveform versus jetting characteristics were performed. The inkjet head has been designed to maximize the droplet velocity, minimize voltage response of the actuator and optimize the firing frequency to eject ink droplet. The head design was carried out by using mechanical simulation. The printhead has been fabricated with Si(100) and SOI wafers by MEMS process and silicon direct bonding method. To investigate how performance of the piezoelectric ceramic actuator influences on droplet diameter and droplet velocity, the method of stroboscopy was used. Also we observed the movement characteristics of PZT actuator with LDV(Laser Doppler Vibrometer) system, oscilloscope and dynamic signal analyzer. Missing nozzles caused by bubbles in chamber were monitored by their resonance frequency. Using the water based ink of viscosity of 4.8 cps and surface tension of 0.025 N/m, it is possible to eject stable droplets up to 20 kHz, 4.4 m/s and above 8 pl at the different applied driving waveforms.

The preparation and Characterization of Bismuth Layered Ferroelectric Thin Films by Sol-Gel Process (솔-젤법을 이용한 Bismuth Layered Structure를 가진 강유전성 박막의 제조 및 특성평가에 관한 연구)

  • 주진경;송석표;김병호
    • Journal of the Korean Ceramic Society
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    • v.35 no.9
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    • pp.945-952
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    • 1998
  • Ferroelectric Sr0.8Bi2.4Ta2O9 stock solutions were prepared by MOD(Metaloganic Decompostion) process. The phase transformation for the layered perovskite of the SBT thin films by changing RTA(Rapid her-mal Annealing) temperatuer from 700$^{\circ}C$to 780$^{\circ}C$ were observed using XRD and SEM. Layered perovskite phase began to appear above 740$^{\circ}C$ and then SBT thin films were annealed at 800$^{\circ}C$ for 1hr for its com-plete crystallization. The specimens showed well shaped hysteresis curves without post annealing that car-ried out after deposition of Pt top electrode. The SBT thin films showed the asymmetric ferroelectric pro-perties. It was confirmed that the properties were caused by interface effect to SBT and electrode by leak-age current density measurement and asymmetric properties reduced by post annealing. At post annealing temperature of 800$^{\circ}C$ remanant polarization values (2Pr) were 6.7 9 ${\mu}$C/cm2 and those of leakage current densities were 3.73${\times}$10-7 1.32${\times}$10-6 A/cm2 at 3, 5V respectively. Also bismuth bonding types of SBT thin film surface were observed by XPS.

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Experimental Study on the Flexural Behaviour of CFRP-bar NSM R.C Beams depending on Adhesive and Anchorage (접착재 종류와 정착구 유무에 따른 탄소막대 매립보강 RC보의 휨 거동에 관한 실험적 연구)

  • Kim, Sung-Won;Lee, Hyung-Geun;Yeo, Hwan-Jun;Park, Sung-Moo
    • Journal of Korean Association for Spatial Structures
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    • v.14 no.4
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    • pp.73-80
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    • 2014
  • For the last decade many bridges and buildings have experienced flexural strengthening with the fiber reinforced polymer(FRP) bonding system, demands for increasing heavy traffic loads and the changing of the code application. Of the many strengthening systems, NSM(near surface mounted) system with FRP has become attractive and popular way of strengthening for the existed RC structures and many studies and applications of this technique have significantly increased all over the world. Meanwhile, polymer mortar that contains much of the same ingredients as cement but includes the addition of certain polymer resins for enhancing desired physical properties, has been used as an alternative adhesive. This paper focuses on flexural behaviour of CFRP-bar NSM system with variables such as kinds of adhesive, anchorage, sectional aspect ratio. Based on the test results and test-to-predicted ratio, this paper provides researchers and practical engineers a fundamental knowledge and intuition.

Experimental Evaluation of Shear Bonding Performance of Wood-Steel Composite Members (목재-강재 합성 부재의 전단 부착 성능에 대한 실험적 평가)

  • Park, Keum-Sung;Lee, Sang-Sup;Kwak, Myong-Keun
    • Journal of Korean Association for Spatial Structures
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    • v.19 no.4
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    • pp.53-60
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    • 2019
  • In this study, an experimental study was carried out to evaluate the bond shear performance according to the shear connector between the glue-laminated timber and steel interface. Ten block shear specimens were fabricated according to the configuration of the adhesive surface of wood and steel. In addition, four test specimens were produced according to the main variable shape of the wood-concrete shear connector. As a result of the block shear test, the shear strength of the steel-wood adhesive is shown to have a shear performance greater than the wood-wood shear strength. As a result of the push-out test according to the shape of the shear connector, the shear strength increased linearly with the attachment area. The complete composite behavior between the glued-laminated timber and the steel can be secured.

Nondestructive Evaluation on Strength Characteristic and Damage Behavior of Al 7075/CFRP Sandwich Composite (Al 7075/CFRP 샌드위치 복합재료의 강도 및 손상특성에 대한 비파괴 평가)

  • Lee, Jin-Kyung;Yoon, Han-Ki;Lee, Joon-Hyun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.11
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    • pp.2328-2335
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    • 2002
  • A hybrid composite material has many potential usage due to the high specific strength and the resistance to fatigue, when compared to other composite materials such as fiber reinforced plastic(FRP) and metal matrix composite(MMC). However, the fracture mechanism of hybrid composite material is extremely complicated because of the bonding structure of metals and FRP. In this study, Al 7075 sheets and carbon epoxy preprags were used to fabricate the hybrid composite. Recently, nondestructive technique has been used to evaluate the fracture mechanism of these composite materials. AE technique was used to clarify the microscopic damage behavior and failure mechanism of A17075/CFRP hybrid composite. It was found that AE paralneters such as AE event, energy and amplitude were effective to evaluate the failure process of Al 7075/CFRP composite. In addition, the relationship between the AE signal and the characteristics of fracture surface using optical microscope was discussed.

Design and manufacture of hybrid polyrnerconcrete bed for high speed machine tool (초고속 공작기계용 Hybrid Poymer Concrete bed 의 설계와 제작)

  • 서정도;임태성;이대길;김태형;박보선;최원선
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2004.04a
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    • pp.404-409
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    • 2004
  • To maximize the productivity in machining molds and dies, machine tools should operate at high speeds. During the high speed operation of moving frames or spindles, vibration problems are apt to occur if the machine tool structures are made of conventional steel materials with inferior damping characteristics. However, self-excited vibration or chatter is bound to occur during high speed machining when cutting speed exceeds the stability limit of machine tool. Chatter is undesirable because of its adverse effect on surface finish, machining accuracy, and tool life. Furthermore, chatter is a major cause of reducing production rate because, if no remedy can be found, metal removal rates have to be lowered until vibration-free performances is obtained. Also, the resonant vibration of machine tools frequently occurs when operating frequency approaches one of their natural frequencies because machine tools have several natural frequencies due to their many continuous structural elements. However, these vibration problems are closely related to damping characteristics of machine tool structures. The polymer concrete has high potential for machine tool bed due to its good damping characteristics with moderate stiffness. This paper presents the use of polymer concrete and sandwich structures to overcome vibration problems. Also, co-cure bonding method for functional part mounting was exhibited experimentally, by which manufacturing time and cost for polymer concrete bed will be remarkably reduced.

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