• Title/Summary/Keyword: Self diffusion

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An Empirical Study of User Resistance Factors to Internet Banking (인터넷뱅킹의 사용자 저항요인에 관한 연구)

  • Park, Byung-Kwon
    • Journal of Korea Society of Industrial Information Systems
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    • v.12 no.5
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    • pp.86-97
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    • 2007
  • For continuous growth and diffusion of internet banking, it is important to investigate user resistance factors to internet banking. This study investigates the effects of individual characteristics, characteristics of internet banking and service quality factors on user resistance to internet banking. Individual characteristics include self-efficacy of computer, self-efficacy of internet banking, attitude to change, and innovative attitude. Characteristics of internet banking include relative advantage, compatibility, complexity, and perceived risk. Service quality was classified as 5 dimensions of SERVQUAL. The results of this study showed that self-efficacy of computer, self-efficacy of internet banking, compatibility, responsiveness, complexity, perceived risk, reliability and empathy had a significant effect on user resistance to internet banking.

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Inadvertent Self-Detachment of Solitaire AB Stent during the Mechanical Thrombectomy for Recanalization of Acute Ischemic Stroke : Lessons Learned from the Removal of Stent via Surgical Embolectomy

  • Kang, Dong-Hun;Park, Jaechan;Hwang, Yang-Ha;Kim, Yong-Sun
    • Journal of Korean Neurosurgical Society
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    • v.53 no.6
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    • pp.360-363
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    • 2013
  • We recently experienced self-detachment of the Solitaire stent during mechanical thrombectomy of acute ischemic stroke. Then, we tried to remove the detached stent and to recanalize the occlusion, but failed with endovascular means. The following diffusion weighted image MRI revealed no significant increase in infarction size, therefore, we performed surgical removal of the stent to rescue the patient and to elucidate the reason why the self-detachment occurred. Based upon the operative findings, the stent grabbed the main thrombi but inadvertently detached at a severely tortuous, acutely angled, and circumferentially calcified segment of the internal carotid artery. Postoperative angiography demonstrated complete recanalization of the internal carotid artery. The patient's neurological deficits gradually improved, and the modified Rankin scale score was 2 at three months after surgery. In the retrospective case review, bone window images of the baseline computed tomography (CT) scan corresponded to the operative findings. According to this finding, we hypothesized that bone window images of a baseline CT scan can play a role in terms of anticipating difficult stent retrieval before the procedure.

Effects of a Structure-centered Cooperative Learning Safety Education Program based on Blended Learning for Elementary School Students (초등학생의 블랜디드 러닝 기반 구조중심협동학습을 적용한 안전교육 프로그램 개발 및 효과)

  • Seong, Jeong Hye
    • Research in Community and Public Health Nursing
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    • v.30 no.1
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    • pp.57-68
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    • 2019
  • Purpose: This study was performed to determine effects of a structure-centered cooperative learning safety education program based on blended learning for elementary school students. Methods: The study is developed in nonequivalent control group non-synchronized design. The subjects included 24 sixth grade students in the experimental group and 23 sixth grade students in the control group, respectively. To prevent diffusion of the experiment, it was carried out from May 20th to June 24th in 2015 with the control group and the other from August 26th to September 30th in 2015 with the experimental group. It was performed on experimental group after the structure-centered cooperative learning safety education program based on blended learning once a week for 6weeks. Data were analyzed by using descriptive statistics, paired t-test and independent t-test. Results: After the intervention, the experimental group showed significant increases in the self-directed learning attitudes and safety behavior compared to the control group except for the academic self-efficacy. Conclusion: The results indicate that the structure-centered cooperative learning safety education program based on blended learning program is effective in safety education for 6th graders.

Changes in Service life in RC Containing OPC and GGBFS Considering Effects of Loadings and Cold Joint (OPC 및 GGBFS를 혼입한 콘크리트의 하중조건과 콜드조인트에 따른 내구수명 변화)

  • Kim, Hyeok-Jung;Kwon, Seung-Jun
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.5 no.4
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    • pp.466-473
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    • 2017
  • RC (Reinforced Concrete) member has varying service life due to varying diffusion characteristics with loading conditions even if it is exposed to constant exterior conditions. In the paper, quantitative parameters are obtained through adopting the previous results for effects of compressive, tensile, and cold joint on chloride diffusion in OPC (Ordinary Portland Cement) and GGBFS (Ground Granulated Blast Furnace Slag) concrete. Service life is evaluated in RC simple beam with 10.0m of span through increasing loading from self weight (2.5kN/m) to the loading to cracking moment (5.5kN/m). In OPC concrete without cold joint, service life changes to 89.4% for tensile region and 101% for compressive region with loadings while GGBFS concrete has 80.0% and 106%, respectively. For cold joint area, GGBFS concrete shows much reduced service life to 82~80% in compressive region and 69~61% in tensile region, which is caused by the lower diffusion in normal condition but relatively higher increasing cold joint effect than OPC concrete.

Applications of the Fast Grain Boundary Model to Cosmochemistry (빠른 입계 확산 수치 모델의 우주화학에의 적용)

  • Changkun Park
    • Korean Journal of Mineralogy and Petrology
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    • v.36 no.3
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    • pp.199-212
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    • 2023
  • Diffusion is a powerful tool to understand geological processes recorded in terrestrial rocks as well as extraterrestrial materials. Since the diffusive exchange of elements or isotopes may have occurred differently in the solar nebula (high temperature and rapid cooling) and on the parent bodies (fluid-assisted thermal metamorphism at relatively low temperature), it is particularly important to model elemental or isotopic diffusion profiles within the mineral grains to better understand the evolution of the early solar system. A numerical model with the finite difference method for the fast grain boundary diffusion was established for the exchange of elements or isotopes between constituent minerals in a closed system. The fast grain boundary diffusion numerical model was applied to 1) 26Mg variation in plagioclase of an amoeboid olivine aggregate (AOA) from a CH chondrite and 2) Fe-Mg interdiffusion between chondrules, AOA, and matrix minerals in a CO chondrite. Equilibrium isotopic fractionation and equilibrium partitioning were also included in the numerical model, based on the assumption that equilibrium can be reached at the interfaces of mineral crystals. The numerical model showed that diffusion profiles observed in chondrite samples likely resulted from the diffusive exchange of elements or isotopes between the constituent minerals. This study also showed that the closure temperature is determined not only by the mineral with the slowest diffusivity in the system, but also strongly depends on the constituent mineral abundances.

Transient Simulation of CMOS Breakdown characteristics based on Hydro Dynamic Model (Hydro Dynamic Model을 이용한 CMOS의 파괴특성의 Transient Simulation해석)

  • Choi, Won-Cheol
    • Journal of the Korean Society of Industry Convergence
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    • v.5 no.1
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    • pp.39-43
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    • 2002
  • In present much CMOS devices used in VLSI circuit and Logic circuit. With increasing a number of device in VLSI, the confidence becomes more serious. This paper describe the mechanism of breakdown on CMOS, especially n-MOS, based on Hydro Dynamic model with device self-heating. Additionally, illustrate the CMOS latch-up characteristics on simplified device structure on this paper.

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Fabrication of Mach-Zehnder Interferometric Modulator Using Proton-Diffused Channel Waveguide (양자확산 LiNbO$_3$ 광도파로를 이용한 Mach-Zehnder 간섭계 구조의 광변조기 제작)

  • 김종성
    • Proceedings of the Optical Society of Korea Conference
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    • 1990.02a
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    • pp.264-268
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    • 1990
  • A guided-wave electro-optic Mach-Zehnder interferometric modulator was fabricated on X-cut LiNbO3 . The channel waveguides were formed by proton diffusion with self-aligned SiO2-cladding. A mach-Zehnder interferometric modulator with arm lengths of 7mm has been fabricated and tested at 0.6328${\mu}{\textrm}{m}$. Its modulation depth with V$\pi$ of only 3.5V was 85% and the 3dB bandwidth was 1.6KHz. For high speed operation, the electrode dimension should be reduced to have smaller R, L, and C.

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Acceleration of the Time-Dependent Radiative Transfer Calculations using Diffusion Approximation

  • Noh, Tae-Wan
    • Proceedings of the Korean Nuclear Society Conference
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    • 2004.10a
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    • pp.151-152
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    • 2004
  • An acceleration technique combined with the discrete ordinates method which has been widely used in the solution of neutron transport phenomena is applied to the solution of radiative transfer equation. The self-adjoint form of the second order radiation intensity equation is used to enhance the stability of the solution, and a new linearization method is developed to avoid the nonlinearity of the material temperature equation. This new acceleration method is applied to the well known Marshak wave problem, and the numerical result is compared with that of a non-accelerated calculation

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Fabrication Process of Laminated Composites by Self-propagating High-temperature Synthesis Reaction (자전고온반응에 의한 적층복합재료의 제조공정)

  • 김희연;정동석;홍순형
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2002.05a
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    • pp.155-158
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    • 2002
  • Fabrication process of metal/intermetallic laminated composites by using self-propagating high temperature synthesis(SHS) reactions between Ni and Al elemental metal foils have been investigated. Al foils were sandwiched between Ni foils and heated in a vacuum hot press to the melting point of aluminium. SHS reaction kinetics was thermodynamically analyzed through the final volume fraction of the unreacted Al related with the initial thickness ratio of Ni:Al and diffusion bonding stage before SHS reaction. Thermal aging of laminated composites resulted in the formation of functionally gradient series of intermetallic phases. Microstructure showed that the main phases of intermetallics were NiAl and $Ni_3Al$ having higher strength at room and high temperatures. The volume fractions of intermetallic phases were measured as 82.4, 58.6, 38.4% in 1:1, 2:1, 4:1 initial thickness ratio of Ni:Al.

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Experimental Study on Behavior near Extinction in Buoyancy-minimized Counterflow Diffusion Flame (부력 효과의 최소화를 통한 소화 근처 대향류 확산화염 거동에 관한 실험적 연구)

  • Chung, Yong Ho;Park, Jeong;Kwon, Oh Boong;Yun, Jin-Han;Keel, Sang-In;Kim, Tae Hyung;Kim, Young Ju
    • 한국연소학회:학술대회논문집
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    • 2012.11a
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    • pp.23-26
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    • 2012
  • Experimental study was conducted to elucidate flame extinction phenomena in counterflow flame. Using a curtain helium flow significantly reduced buoyancy such that the flame can be positioned at the center between the upper and lower nozzles even at the velocity ratio of 1.0. The curves of critical diluent mole fraction versus global strain rate have C-shapes. The flame oscillation was observed prior to low strain rate flame extinction at both flame conditions with and without minimizing buoyancy force. The results show that, at low strain rate flame, the self-excitation frequency with the order of 1.0 Hz in the case of utilizing pure helium gradually decreases in increase of $N_2$ mole fraction in the curtain flow, meaning that buoyancy suppresses the self-excitation of the outer edge flame.

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