• Title/Summary/Keyword: C-scan

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Effect of Laser Beam on Structural, Optical, and Electrical Properties of BaTiO3 Nanoparticles during Sol-Gel Preparation

  • Mostafa, Massaud;Ebnalwaled, Khaled;Saied, Hussien A.;Roshdy, Reham
    • Journal of the Korean Ceramic Society
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    • v.55 no.6
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    • pp.581-589
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    • 2018
  • This work concentrated on the effect of different laser beams on the microstructure and dielectric properties of $BaTiO_3$ nanoparticles at different calcinations times during the gelling preparation step. The nanoparticles were prepared by the sol-gel method. A green (1000 mW, 532 nm) and red laser beam (500 mW, 808 nm), were applied vertically at the center of stirring raw materials. The samples were sintered at $1000^{\circ}C$ for 2, 4, and 6 h. X-ray diffraction (XRD) analysis showed that samples prepared under the green laser have the highest purity. The FT-IR spectra showed that the stretching and bending vibrations of TiO bond without any other bonds, which are compatible to the X-ray diffraction (XRD) results. Samples were characterized by transmission electron microscopy (TEM), Scan electron microscopy (SEM), and UV-Visible spectrophotometer. Characterization showed the samples prepared under the green laser to have the highest particle size (~ 50 nm) and transparency for all sintering durations. Laser beam effects on electrical characterization were studied. BT nanoparticles prepared under the green laser show the higher dielectric constant, which was found to increase with sintering temperature.

A Comparison of Flow Condensation HTCs of R22 Alternatives in the Multi-Channel Tube (알루미늄 다채널 평판관내 R22의 흐름응축 열전달 성능 비교)

  • Seo, Young-Ho;Lim, Dae-Taeg;Park, Ki-Jung;Jung, Dong-Soo
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1270-1275
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    • 2004
  • Flow condensation heat transfer coefficients(HTCs) of R22 and R134a were measured on horizontal aluminum multi-channel tube. The experimental apparatus was composed of three main parts ; a refrigerant loop, a water loop and a water-ethylene glycol loop. The test section in the refrigerant loop was made of aluminum multi-channel tube of 1.4 mm hydraulic diameter and 0.53 m length. The refrigerant was cooled by passing cold water through an annulus surrounding the test section. The data scan vapor qualities $(0.1{\sim}0.9)$, mass flux ($200{\sim}400$ $kg/m^{2}s$) and heat flux ($7.3{\sim}7.7$ $kW/m^{2}$) at $40{\times}0.2^{\circ}C$ saturation temperature in small hydraulic diameter tube. It was found that some well-known previous correlations were not suitable for multichannel tube. So, It must develop new correlations for multi-channel tubes.

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DETECTION OF MICROSCOPIC BEHAVIOR OF LOW VELOCITY IMPACT DAMAGED CFRP LAMINATE UNDER TENSILE LOADING BY ELASTIC WAVES (탄성파 응용기술에 의한 CFRP 복합재료의 저속충격 손상역의 미시적 거동 특성 탐지)

  • 이준현;권오양;이승석
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1993.10a
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    • pp.650-655
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    • 1993
  • Carbon/epoxy composite(CFRP) coupons previously damaged by low velocity impact were tested under static tensile loading and microscope progress of damage was characterized by ultrasonic C-scan, Scanning Acoustic Microscopy (SAM) and Acoustic Emission(AE) techniques which were based on the application of elastic waves. The degress of impact damage has been correlated with the AE activity during monotonic or loading/unloading tensile testing as well as the result of ultrasonic test. The coupons were subjected to impact velocities ranged from 0.71 to 2.17 m/sec, which introduced the amount of damage rated as 0%, 10%, 30%, and 50% with reference to the total absorbed energy at fracture. Special attention was paid to determine optimal AE parameters to characterize the microscopic fracture process and to predict the residual strength of composite laminates. AE RMS voltage during the early stage of tensile loading was found an effective parameter to quantify the degree of impact damage. It was also found that the Felicity ratio is closely related to the stacking sequence and the residual strength of the CFRP laminates.

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A Development of High Power Activated Carbon Using the KOH Activation of Soft Carbon Series Cokes

  • Kim, Jung-Ae;Park, In-Soo;Seo, Ji-Hye;Lee, Jung-Joon
    • Transactions on Electrical and Electronic Materials
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    • v.15 no.2
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    • pp.81-86
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    • 2014
  • The process parameter in optimized KOH alkali activation of soft carbon series coke material in high purity was set with DOE experiments design. The activated carbon was produced by performing the activation process based on the set process parameters. The specific surface area was measured and pore size was analyzed by $N_2$ absorption method for the produced activated carbon. The surface functional group was analyzed by Boehm method and metal impurities were analyzed by XRF method. The specific surface area was increased over 2,000 $m^2/g$ as the mixing ratio of activation agent increased. The micro pores in $5{\sim}15{\AA}$ and surface functional group under 0.4 meq/g were obtained. The contents of the metal impurity in activated carbon which is the factor for reducing the electrochemical characteristics was reduced less than 100 ppm through the cleansing process optimization. The electrochemical characteristics of activated carbon in 38.5 F/g and 26.6 F/cc were checked through the impedance measuring with cyclic voltammetry scan rate in 50~300 mV/s and frequency in 10 mHz ~100 kHz. The activated carbon was made in the optimized activation process conditions of activation time in 40 minutes, mixing ratio of activation agent in 4.5 : 1.0 and heat treatment temperature over $650^{\circ}C$.

Giant esophageal schwannoma (식도에 발생한 거대 신경초종)

  • Kim, Min Jae;Song, Joon Cheol;Kim, Il;Yun, Jin Tak;Kim, Young Woo;Choi, Young;Joo, Yeon-Ho;Kang, Chang Hyun
    • Journal of Yeungnam Medical Science
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    • v.33 no.1
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    • pp.21-24
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    • 2016
  • Esophageal schwannoma is a very rare submucosal tumor. We report successful management of esophageal schwannoma in a 41-year-old man who complained of progressively worsening dysphagia. A huge submucosal tumor was found via endoscopy and a chest computed tomography scan. Esophagectomy was performed with no post-operative complications. Post-operative immunohistochemistry staining showed a positive result for S-100 and negative results for c-kit and CD34. The post-operative mild dysphagia persisted, and the follow-up endoscopic findings revealed anastomosis site stenosis. Approximately 2 months later, we performed endoscopic balloon dilatation. We report herein a case of esophageal schwannoma with reviews.

Thermoelectric Properties of p-type 25% $Bi_{2}Te_{3}+75%Sb_{2}Te_{3}$ Materials Prepared by Rapid Solidification Process and Hot Pressing (급속응고기술에 의한 p-type 25% $Bi_{2}Te_{3}+75% Sb_{2}Te_{3}$ 열간압축제의 열전특성)

  • 김익수
    • Journal of Powder Materials
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    • v.3 no.4
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    • pp.246-252
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    • 1996
  • $Bi_{2}Te_{3}-Sb_{2}Te_{3}$, $Bi_{2}Te_{3}-Bi_{2}Se_{3}$ solid solutions are of great interest as materials for thermoelectric energy conversion. One of the key technologies to ensure the efficiency of thermoelectric device is to obtain chemically homogeneous solid solutions. In this work, the new process with rapid solidification followed by hot pressing was investigated to produce homogeneous thermoelectric materials. Characteristics of the materials were examined with XRD, SEM, EPMA-line scan and bending test. Property variations of the materials were investigated as a function of variables, such as excess Te quantity and hot pressing temperature. Quenched ribbons are very brittle and consisted of homogeneous $Bi_{2}Te_{3}$, $Sb_{2}Te_{3}$ solid solutions. When the process parameters were optimized, the maximum figure of merit was 3.073$\times$$10^{-3}K^{-4}$. The bending strength of the material, hot pressed at 45$0^{\circ}C$, was 5.87 kgf/${mm}^2$.

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Remote sensing and photogrammetry techniques in diagnostics of concrete structures

  • Janowski, Artur;Nagrodzka-Godycka, Krystyna;Szulwic, Jakub;Ziolkowski, Patryk
    • Computers and Concrete
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    • v.18 no.3
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    • pp.405-420
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    • 2016
  • Recently laser scanning technologies become widely used in many areas of the modern economy. In the following paper authors show a potential spectrum of use Terrestrial Laser Scanning (TLS) in diagnostics of reinforced concrete elements. Based on modes of failure analysis of reinforcement concrete beam authors describe downsides and advantages of adaptation of terrestrial laser scanning to this purpose, moreover reveal under which condition this technology might be used. Research studies were conducted by Faculty of Civil and Environmental Engineering at Gdansk University of Technology. An experiment involved bending of reinforced concrete beam, the process was registered by the terrestrial laser scanner. Reinforced concrete beam was deliberately overloaded and eventually failed by shear. Whole failure process was tracing and recording by scanner Leica ScanStation C10 and verified by synchronous photographic registration supported by digital photogrammetry methods. Obtained data were post-processed in Leica Cyclone (dedicated software) and MeshLab (program on GPL license). The main goal of this paper is to prove the effectiveness of TLS in diagnostics of reinforced concrete elements. Authors propose few methods and procedures to virtually reconstruct failure process, measure geometry and assess a condition of structure.

Design of PCI/USB Interface Controller with IEEE 1149.1 Test Function (IEEE 1149.1 테스트 기능이 내장된 PCI/USB 통합 인터페이스 회로의 설계)

  • Kim, Young-Hun;Kim, Ki-Tae;Park, Sung-Ju
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.43 no.10 s.352
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    • pp.54-60
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    • 2006
  • In order to test the board with IEEE 1149.1 boundary scan design, the test sequence must be applied as the bit stream However it is very tedious job to generate the test bit sequence since it requires the complete hlowledge about the 1149.1. This fuper introduces a convenient PCI/USB interface controller, named as Test-Ready PCI (TRPCI) ard Test-Ready USB (TRUSB). Test Bus Controller has been developed by TI and Lucent aiming to generate the test bit stream as an instruction level, thus even the novice test engineer can easily generate the test sequence.

Interval Scan Inspection Technique for Contact Failure of Advanced DRAM Process using Electron Beam-Inspection System

  • Oh, J.H.;Kwon, G.;Mun, D.Y.;Kim, D.J.;Han, I.K.;Yoo, H.W.;Jo, J.C.;Ominami, Y.;Ninomiya, T.;Nozoe, M.
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.12 no.1
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    • pp.34-40
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    • 2012
  • We have developed a highly sensitive inspection technique based on an electron beam inspection for detecting the contact failure of a poly-Si plugged layer. It was difficult to distinguish the contact failure from normal landing plugs with high impedance. Normally, the thermal annealing method has been used to decrease the impedance of poly-Si plugs and this method increases the difference of charged characteristics and voltage contrast. However, the additional process made the loss of time and broke down the device characteristics. Here, the interval scanning method without thermal annealing was effectively applied to enhance the difference of surface voltage between well-contacted poly-Si plugs and incomplete contact plugs. It is extremely useful to detect the contact failures of non-annealed plug contacts with high impedance.

Damage propagation in CFRP laminates subjected to low velocity impact and static indentation

  • Aoki, Yuichiro;Suemasu, Hiroshi;Ishikawa, Takashi
    • Advanced Composite Materials
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    • v.16 no.1
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    • pp.45-61
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    • 2007
  • This paper describes a damage accumulation mechanism in cross-ply CFRP laminates $[0_2/90_2]_{2S}$ subjected to out-of-plane loading. Drop-weight impact and static indentation tests were carried out, and induced damage was observed by ultrasonic C-scan and an optical microscope. Both tests gave essentially the same results for damage modes, sizes, and load-deformation history. First, a crack occurred in the bottom $0^{\circ}$ layer accompanying some delamination along the crack caused by bending stress. Then, transverse cracks occurred in the middle $90^{\circ}$ layer with decreasing contact force between the specimen and the indenter. Measured local strains near the impact point showed that the stress state changed from a bending dominant state to an in-plane tensile dominant state. A cohesive interface element was used to simulate the propagation of multiple delaminations and transverse cracks under static indentation. Two types of analytical models are considered, one with multiple delaminations and the other with both multiple delaminations and transverse cracks. The damage obtained for the model with only multiple delaminations was quite different from that obtained from the experiment. However, the results obtained from the model with both delaminations and transverse cracks well explain the characteristics of the damage obtained in the experiment. The existence of the transverse cracks is essential to form the characteristic impact damage.