• Title/Summary/Keyword: THICKNESS

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Dielectric and Piezoelectric Characteristics of Low Temperature Sintering PbTiO3 System Ceramics with amount of Bi2O3 Addition (Bi2O3 첨가량에 따른 저온소결 PbTiO3계 세라믹스의 유전 및 압전특성)

  • Yoo, Ju-Hyun;Kim, Do-Hyung;Lee, Sang-Ho;Sohn, Eun-Young
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.20 no.9
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    • pp.771-775
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    • 2007
  • In this study, in order to develop low temperature sintering ceramics for thickness vibration mode multilayer piezoelectric transformer, $PbTiO_3$ system ceramics were fabricated using $Na_2CO_3,\;Li_2CO_3,\;MnO_2\;and\;Bi_2O_3$ as sintering aids and their dielectric and piezoeletric properties were investigated according to the amount of $Bi_2O_3$ addition. At the sintering temperature of $900^{\circ}C\;and\;Bi_2O_3$ addition of 0.1 wt%, density, grain size, thickness vibration mode eletromechanical coupling factor($k_t$), thickness vibration mode mechanical quality factor($Q_{mt}$) and dielecteic constant(${\varepsilon}_r$) showed the optimum value of $6.94g/cm^3,\;2.413{\mu}m$, 0.497, 3,162 and 209, respectively, for thickness vibration mode multilayer piezoelectric transformer application.

The Effects of Nanocrystalline Silicon Thin Film Thickness on Top Gate Nanocrystalline Silicon Thin Film Transistor Fabricated at 180℃

  • Kang, Dong-Won;Park, Joong-Hyun;Han, Sang-Myeon;Han, Min-Koo
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.8 no.2
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    • pp.111-114
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    • 2008
  • We studied the influence of nanocrystalline silicon (nc-Si) thin film thickness on top gate nc-Si thin film transistor (TFT) fabricated at $180^{\circ}C$. The nc-Si thickness affects the characteristics of nc-Si TFT due to the nc-Si growth similar to a columnar. As the thickness of nc-Si increases from 40 nm to 200 nm, the grain size was increased from 20 nm to 40 nm. Having a large grain size, the thick nc-Si TFT surpasses the thin nc-Si TFT in terms of electrical characteristics such as field effect mobility. The channel resistance was decreased due to growth of the grain. We obtained the experimental results that the field effect mobility of the fabricated devices of which nc-Si thickness is 60, 90 and 130 nm are 26, 77 and $119\;cm^2/Vsec$, respectively. The leakage current, however, is increased from $7.2{\times}10^{-10}$ to $1.9{\times}10^{-8}\;A$ at $V_{GS}=-4.4\;V$ when the nc-Si thickness increases. It is originated from the decrease of the channel resistance.

A Study on the Brazing Bondinf Conditions of A1050 Using Al-Si Alloy Filler Metal (Al-Si계 필러메탈을 이용한 A1050알루미늄의 브레이징 접합조건에 관한 연구)

  • 김정일;김영식
    • Journal of Advanced Marine Engineering and Technology
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    • v.17 no.1
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    • pp.66-72
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    • 1993
  • The brazing of Al to Al using Al-Si alloy filler metal was performed under different bonding conditions such as ratio of lap length to plate thickness, surface roughness and joint clearance of the lap joint. The adopted thickness of the base metal in this experiments were two kinds of 4mm and 7mm which were most commonly used in various field. Influence of several bonding conditions of Al/Al joint was quantitavely evaluated by bonding strength test, and microstructural analysis at the interlayer were performed by optical microscope. From above experiments, the optimum bonding conditions of the brazing bonding of Al/Al using Al-Si alloy filler metal was determined. The major results obtained are as follows. 1) The fracture occurs at brazed joint in the conditions of that the ratio of lap length to plate thickness is less than 2 in case of 7mm plate thickness. 2) The ratio of lap length to plate thickness which the fracture occurs at base metal is decreased with the decreasing of the plate thickness. 3) The joint strength is not affected by the surface roughness and joint clearance of the brazed part. 4) The heat-treatment of the brazed joint contribute to eliminate the boundary between the base metal and filler metal. However, the joint strength is not affected by the heat-treatment.

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Development of Tomograph Technique for Evaluating Thickness Reduction using Noncontact Ultrasonic Sensor Network (두께감육 평가를 위한 비접촉식 초음파 센서 네트워크를 이용한 토모그래프 기술 개발)

  • Lee, J.M.;Kim, Y.K.;Park, I.K.
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.23 no.1
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    • pp.27-31
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    • 2014
  • This paper describes a tomographic imaging technique for evaluating the thickness reduction of a plate-like structure using a noncontact sensor network based on an electromagnetic acoustic transducer that generates shear horizontal plate waves. Because this technique is based on the effect of mode cutoff and time of flight of guided waves caused by a change in thickness, the tomographic image provides information on the presence of defects in the structure. To verify the performance of the method, artificial defects with various thickness reduction ratios were machined in an aluminum plate, and the tomographic imaging results are reported. The results show that the generated tomographic image displays the thickness reductions and can identify their locations. Therefore, the proposed technique has good potential as a tool for health monitoring of the integrity of plate-like structures.

Comparison of the Abdominal Muscle Thickness and Activity by Using Tool and Unstable Surface which is Accompanied Bridge Exercise Doing Abdominal Drawing-in Breath (불안정 지지면에서 복부 드로잉-인 호흡을 동반한 교각운동 시 사용도구에 따른 복부 근육 두께 및 활성도 비교)

  • Kim, Hyeonsu;Bae, Wonsik;Lee, Keoncheol
    • Journal of The Korean Society of Integrative Medicine
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    • v.5 no.1
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    • pp.25-34
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    • 2017
  • Purpose : The purpose of this study was to identify comparison of the abdominal muscle thickness and activity by using tool and unstable surface which is accompanied bridge exercise doing abdominal drawing-in breath. Method : This study was performed on normal 13 males and 17 females subjects doing bridge exercise accompanied abdominal drawing-in breath used tools. At this time muscle thickness and muscle activity is measured through ultrasound and EMG. Result : The results of this study, rectus abdominis, internal oblique and transverse abdominis showed a significant difference in muscle thickness when performed using pilates circle. And external oblique showed a significant difference muscle thickness when performed using gym ball. Rectus abdominis and external oblique showed a significant difference in muscle activity when performed using pilates circle. And internal oblique showed a significant difference in muscle activity when performed using sling. Conclusion : Therefore it is suggested that it would be effective to apply the gymball and pilates circle in the unstable surface for abdominal weakness.

Evaluation of Local Allowable Wall Thickness of Thinned Pipe Subjected to Internal Pressure and Bending Moment (내압과 굽힘하중하에서 감육배관의 국부허용두께 평가)

  • Kim, Jin-Won;Park, Chi-Yong;Kim, Beom-Nyeon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.1
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    • pp.81-88
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    • 2001
  • This study proposed an analytical method to evaluate a local allowable wall thickness (LAWT) for locally thinned pipe subjected to internal pressure and bending moment. In this method, the stresses in the thinned region were calculated by finite element analysis and plastic collapse was applied as a failure criterion of thinned pipe. Using this method, LAWT for a simplified thinned pipe was evaluated with variation in axial extent of thinned area, and it was compared with allowable wall thickness provided by previous pipe wall thickness criteria. The results showed that the LAWT was lower, about 50%, than that calculated by construction code or ASME Code N-597, and it was higher, about 2 times, than that estimated by evaluation model based on pipe experiments. In addition, LAWT was decreased with increasing axial extent of thinned area and saturated with further increase in axial extent. And, the variation in LAWT with axial extent of thinned area depended on type of load, especially a magnitude of bending moment, considering in the evaluation.

A Fatigue Related Equation with Shape and Loading Factors Representing Effect of Thickness in Al 2024-T3 Alloy Sheet (판재 Al 2024-T3 합금재료의 두께효과를 나타내는 형상인자 및 하중인자에 의한 피로관계식)

  • Kim, Seung-Gwon;Lee, Ouk-Sub;Jang, Joo-Sup
    • Transactions of the Korean Society of Automotive Engineers
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    • v.20 no.1
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    • pp.141-146
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    • 2012
  • Aluminum alloys have been used with various thicknesses suitable for light weight of structure. It is known that the thickness effect of material is an important factor affecting fatigue crack propagation under constant fatigue stress condition. In this work, we presented the behavior of fatigue crack propagation in thin plate compared to thick plate Al 2024-T3 alloy with referred thickness effect in a correlative equation determined by the shape factor and the loading factor. We chose two factors that are used in the correlative equation with considering that the experiments were carried out under a constant fatigue stress condition. The thickness ratio of thin plate compared to thick plate and the equivalent effective stress intensity factor ratio depending on thickness were chosen as shape and loading factors. A correlative equation is utilized to determine the equivalent effective stress intensity factor range of thin plate and identify the degree of increasing phenomenon of fatigue life in thin plate compared to thick plate.

Influence of Mold Temperature on the Thickness of a Skin Layer and Impact Strength in the Microcellular Injection Molding Process (초미세 발포 사출공정에서 금형의 온도가 스킨층 두께와 충격강도에 미치는 영향)

  • Lee J.J.;Cha S.W.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1630-1635
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    • 2005
  • The microstructure of the parts made by the microcellular injection molding process influence properties, including impact strength, tensile strength and density of material. Microstructure of microcellular plastics is divided into core foaming region and solid skin region. Core foaming region is influenced by pressure drop rate, viscosity and cell coalescence. However, actual mechanism of the skin layers is not known despite its importance. The study on the skin layer is getting important because foaming rate of the plastics is determined by the thickness ratio of the skin layer. Especially in case of large molded part, control of the skin layer is needed because skin layer thickness is changed largely. Therefore it is necessary to study variation in skin layer thickness with processing parameters. In this paper, the influence of temperatures in the mold cavity on the skin layer s thickness was also addressed. In addition, the relationship between the temperature distributions across cavity of the mold with impact strength on parts made with the microcellular injection molding process was addressed. In addition, the method to predict the variation in skin layer thickness with mold temperature is discussed.

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Study on Press-drying and Air-drying of Italian Poplar Rotary Veneer (이태리포플러 로타리 단판(單板)의 열판건조(熱板乾燥)와 천연건조(天然乾燥)에 관(關)한 연구(硏究))

  • Jung, Hee-Suk;Shim, Chong-Supp
    • Journal of the Korean Wood Science and Technology
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    • v.10 no.3
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    • pp.167-167
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    • 1982
  • Italian poplar (Populus euramericana) rotary veneers were press-dried and air-dried to study drying curves, thickness shrinkage and width shrinkage of them under several drying conditions such as drying temperatures and veneer thicknesses. The results of the study are summarized as follows; 1. In press-drying, drying times from green condition to about final moisture content of 10 percent with veneer thickness of 0.6mm by platen temperatures required about 10 minutes at platen temperature of $100^{\circ}C$, 3 minutes at $110^{\circ}C$, 1 minute at $120^{\circ}C$ and $130^{\circ}C$, respectively. 2. In press, drying, drying times from green condition to about final moisture content of 10 percent by veneer thicknesses required 2 minutes at veneer thickness of 0.6mm, 4 minutes at 1.2mm,6 minutes at 1.8mm and 9 minutes at 3.6mm, respectively. 3. In air-drying, drying times from green condition to air-dried moisture content by veneer thicknesses required 15 hours at veneer thickness of 0.6mm, 18 hours at 1.2mm and 23 hours at 2.4mm, respectively. 4. Thickness shrinkage of press-drying was remarkably greater than that of air-drying, but width shrinkage of press-drying was rather smaller. 5. Difference of thickness shrinkage among platen temperatures was insignificant, and width shrinkage at platen temperature of $130^{\circ}C$ was the least.

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Morphology and Electrical Properties of Back Electrode for Solar Cell Depending on the Mo : Na/Mo Bilayer Thickness (Mo : Na/Mo 이중층 구조 두께에 따른 태양전지 후면전극의 조직 및 전기적 특성)

  • Shin, Younhak;Kim, Myunghan
    • Korean Journal of Materials Research
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    • v.23 no.9
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    • pp.495-500
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    • 2013
  • Mo-based thin films are frequently used as back electrode materials because of their low resistivity and high crystallinity in CIGS chalcopyrite solar cells. Mo:Na/Mo bilayer thin films with $1{\mu}m$ thickness were deposited on soda lime glass by varying the thickness of each layer using dc-magnetron sputtering. The effects of the Mo:Na layer on morphology and electrical property in terms of resistivity were systematically investigated. The resistivity increased from $159{\mu}{\Omega}cm$ to $944{\mu}{\Omega}cm$; this seemed to be caused by increased surface defects and low crystallinity as the thickness of Mo:Na layer increased from 100 nm to 500 nm. The surface morphologies of the Mo thin films changed from a somewhat coarse fibrous structures to irregular and fine celled structures with increased surface cracks along the cell boundaries as the thickness of Mo:Na layer increased. Na contents varied drastically from 0.03 % to 0.52 % according to the variation of Mo:Na layer thickness. The change in Na content may be ascribed to changes in surface morphology and crystallinity of the thin films.