• Title/Summary/Keyword: Self diffusion

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Influence of Fuel concentration gradient on the Extinction Behavior in Buoyancy minimized Counterflow Diffusion Flame (부력을 최소화한 대향류 확산화염 소화거동에서 연료농도구배의 영향)

  • Park, Jin Wook;Park, Jeong;Yun, Jin-Han;Keel, Sang-In
    • 한국연소학회:학술대회논문집
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    • 2014.11a
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    • pp.379-381
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    • 2014
  • Influence of fuel concentration gradient was investigated near flame extinction limit in buoyancy-suppressed non-premixed counterflow flame with triple co-flow burner. The use of He curtain flow produced a microgravity level of $10^{-2}-10^{-3}g$ in He-diluted non-premixed counter triple co-flow flame experiments. Flame stability map was presented based on flame extinction and oscillation near extinction limit. The stability map via critical diluent mole fraction with global strain rate was represented by varying outer and inner He-diluted mole fractions. The flame extinction modes could be classified into five: an extinction through the shrinkage of the outmost edge flame forward the flame center with and without self-excitation, respectively ((I) and (II)), an extinction via the rapid expansion of a flame hole while the outmost edge flame is stationary (III), both the outermost and the center edge flames oscillate, and then a donut shaped flame is formed or the flame is entirely extinguished (IV), a shrinkage of the outermost edge flame without self-excitation followed by shrinking or sustain the inner flame (V).

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Development of a User Centered Web Site for Mental Health Management in Adolescents (초고속 통신망을 이용한 청소년의 정신건강관리 지원시스템 개발)

  • Bae, Jeong-Yee
    • Journal of Korean Academy of Nursing
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    • v.37 no.1
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    • pp.14-25
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    • 2007
  • Purpose: A user centered web-based mental health management system may be particularly useful in Korea where there is widespread diffusion of personal computers and internet connectivity. The purpose of this paper was to describe the development of a web-based system for mental health management in adolescents using principals of a user centered design. Method: Our design process includes five distinct phases: needs assessment, analysis, design, development/testing/revision, and application release. Results: Web content includes an introduction, information about mental health management in adolescents, self-assessment and guidance, interventions for improving mental health, directory of self-help groups, and counseling and additional community resources. The web site was released using the URL: http://www.baejy.com/youth. Conclusion: The end result was a web based mental health management system for adolescents with a high degree of usability. The author believes that web-based mental health interventions in the future have true potential in helping Koreans who are suffering, or at risk, for mental health problems, particularly because of the stigma related to psychiatric therapy in Korea.

Rural Youth's Leisure Activity and Measures for Activation (농촌청소년의 여가활동 활성화방안)

  • Choi, Chang-Wook;Lee, Chae-Shik
    • Journal of Agricultural Extension & Community Development
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    • v.11 no.1
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    • pp.95-110
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    • 2004
  • The purposes of this study were to analyze rural youth's leisure activity and to suggest measures for activation. This study was conducted by review of literature and questionnaire, The data was collected from 1,209 stratified cluster random sampled rural youth who are in middle school and high school. To analyze the data, SPSS/WIN program was employed. The major finding of the study were as follows: 1) About 30% of rural youths had less than 1-2 hours for leisure activity in daily life and more than 8 hours for leisure activity during the weekend, and over 40% of rural youths had no plan for leisure activity. 1) They recognized that leisure activity made them enjoy common life, decrease their stress, and get new experience far self-development, 3) participation in sports, organized-activity and self-directed activity of the middle schools youths were higher compare to youths in high schools, 4) to activate leisure life, rural youths expected to get a) direct support for participating leisure activity expenses(27%), b) develop and diffusion of diverse and interesting leisure programs(23%), and c) securing appropriate leisure facilities(22%).

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Characteristic Analysis of Cyclic Voltammetry on a Self-Assembled Mono-layer Electrode (자가조립 단층 전극에 대한 순환전위법의 특성해석)

  • Cho, Hana;Yoon, Do-Young
    • Journal of the Korean Electrochemical Society
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    • v.16 no.4
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    • pp.217-224
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    • 2013
  • In this paper, we have investigated the characteristics of cyclic voltammetry of a self-assembled mono-layer(SAM) electrode which was modified by 3-Mercaptopropionic acid (3-MPA) on gold nanoparticle(AuNP)-deposited electrode. Also, the transport phenomena of electrons and ions around the electrode have been analyzed. The governing equation and its boundary conditions by adopting the semi-infinite diffusion model were formulated for the mass-transfer dominant system. In order to obtain the numerical solutions of cyclic voltammetry(CV) on SAM electrodes, MATLAB program was implemented by applying the explicit finite difference method. Resulting CV program for the SAM-modified electrode was verified in good agreements with the experimental CV results for the 3-MPA on AuNP electrode.

An Amorphous Silicon Local Interconnection (ASLI) CMOS with Self-Aligned Source/Drain and Its Electrical Characteristics

  • Yoon, Yong-Sun;Baek, Kyu-Ha;Park, Jong-Moon;Nam, Kee-Soo
    • ETRI Journal
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    • v.19 no.4
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    • pp.402-413
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    • 1997
  • A CMOS device which has an extended heavily-doped amorphous silicon source/drain layer on the field oxide and an amorphous silicon local interconnection (ASLI) layer in the self-aligned source/drain region has been studied. The ASLI layer has some important roles of the local interconnections from the extended source/drain to the bulk source/drain and the path of the dopant diffusion sources to the bulk. The junction depth and the area of the source/drain can be controlled easily by the ASLI layer thickness. The device in this paper not only has very small area of source/drain junctions, but has very shallow junction depths than those of the conventional CMOS device. An operating speed, however, is enhanced significantly compared with the conventional ones, because the junction capacitance of the source/drain is reduced remarkably due to the very small area of source/drain junctions. For a 71-stage unloaded CMOS ring oscillator, 128 ps/gate has been obtained at power supply voltage of 3.3V. Utilizing this proposed structure, a buried channel PMOS device for the deep submicron regime, known to be difficult to implement, can be fabricated easily.

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Self-Aligned $n^+$ -pPolysilicon-Silicon Junction Structure Using the Recess Oxidation (Recess 산화를 이용한 자기정렬 $n^+$ -p 폴리실리콘-실리콘 접합구조)

  • 이종호;박영준;이종덕;허창수
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.30A no.6
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    • pp.38-48
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    • 1993
  • A recessed n-p Juction diode with the self-aligned sturcture is proposed and fabricated by using the polysilicon as an n$^{+}$ diffusion source. The diode structure can be applicable to the emitter-base formation of high performance bipolar divice and the n$^{+}$ polysilicone mitter has an important effect on the device characteristics. The considered parameters for the polysilicon formation are the deposition condition. As$^{+}$ dose for the doping of the polysilicon and the annealing condition using RTP system. The vertical depth profiles of the fabricated diode are obtained by SIMS and the electrical characteristics are analyzed in terms of the ideality factor of diode (n), contact resistance and reverse leakage current. In addition, n$^{+}$-p junction diodes are formed by using the amorphous silicon (of combination of amorphous and polysiliocn) instead of polysilicon and their characteristics are compared with those of the standard sample. The As$^{+}$ dose for the formation of good junction is about 1~2${\times}10^{16}cm^{2}$ at given RTA conditions (1100.deg. C, 10sec).

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Intrinsic and Extrinsic Factors Impacting Individuals' Cyber Ethics Awareness and Behavior Intention (사이버윤리 준수인식과 행동의도에 영향을 미치는 사용자의 내·외적요인)

  • Kim, Sanghyun;Park, Hyunsun
    • The Journal of Information Systems
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    • v.23 no.1
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    • pp.111-138
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    • 2014
  • As the Internet is widely used worldwide, Cyber world has become a part of daily life. On the other hand, the adverse effects of Internet, such as abusive comments, illegal harmful contents, rumor diffusion, infringement on a right have emerged with the increase. Researchers recognized the important of cyber ethics as an effective means of coping with the adverse effects on Internet. But, Little empirical research has been related to cyber ethics in management information systems. Thus, the purpose of this research is to identify multidimensional motivation factors that cyber ethics awareness and compliance behavior Intention. For this, this study investigated the factors that might influence Internet users to compliance cyber ethics. Using university students as a sample, one hundred and ninety six are collected for further analysis. The results of this study are as follows; First, self-esteem, Moral Obligation, self-control, cyber ethics education and Social Influence are significantly related to cyber ethics awareness, while punishment is not significantly related. Second, cyber ethics awareness have a positive effect on cyber ethics compliance behavior Intention. Third, the moderating effect of ego strength is also significant. This study is significant in that it established a behavior model to understand the compliance of cyber ethics with internet user in Korea.

PARTICLE ACCELERATION IN SUPERNOVA REMNANTS

  • KANG, HYESUNG
    • Publications of The Korean Astronomical Society
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    • v.30 no.2
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    • pp.545-548
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    • 2015
  • Most high energy cosmic rays (CRs) are thought to be produced by diffusive shock acceleration (DSA) in supernova remnants (SNRs) within the Galaxy. Plasma and MHD simulations have shown that the self-excitation of MHD waves and amplification of magnetic fields via plasma instabilities are an integral part of DSA for strong collisionless shocks. In this study we explore how plasma processes such as plasma instabilities and wave-particle interactions can affect the energy spectra of CR protons and electrons, using time-dependent DSA simulations of SNR shocks. We demonstrate that the time-dependent evolution of the shock dynamics, the self-amplified magnetic fields and $Alfv{\acute{e}nic$ drift govern the highest energy end of the CR energy spectra. As a result, the spectral cutoffs in nonthermal X-ray and ${\gamma}$-ray radiation spectra are regulated by the evolution of the highest energy particles, which are injected at the early phase of SNRs. We also find that the maximum energy of CR protons can be boosted significantly only if the scale height of the magnetic field precursor is long enough to contain the diffusion lengths of the particles of interests. Thus, detailed understandings of nonlinear wave-particle interactions and time-dependent DSA simulations are crucial for understanding the nonthermal radiation from CR acceleration sources.

MEMBRANES FOR GAS AND LIQUID SEPARATIONS

  • Golemme, Giovanni;Bove, Lucia;Clarizia, Gabriele;Muzzalupo, Rita;Ranieri, Giuseppe;Nam, Sang-Yong;Drioli, Enrico
    • Proceedings of the Membrane Society of Korea Conference
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    • 1999.07a
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    • pp.27-30
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    • 1999
  • Poly(phenylene oxide)s were used to prepare flat, integrally skinned self-supporthed asymmetric membranes by dry-wet phase separption. The intrinsic ideal gas selectivity of poly- (2,6-dimethy-1,4-phenylene oxide) (PMPO) was retained in the membranes, and improved by a coating with silicone rubber. Polymers of the same class were coated of UF supports with a silicon rubber gutter layer, yielding composite membranes with high flux but lower selectivity. The effect of th glutaraldehyde cross-linking of sodium alginate (SA) membranes on the mobility of water and ethanol has been studied with pfg nmr. Crosslinking reduces water self-diffusion, and does not seem to be stable on the timescale of weeks.

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Alignment of Metal Halide Perovskite Nanowires and Their Application in Photodetectors (금속 할라이드 페로브스카이트 나노와이어의 광 센서 소자 응용)

  • Sihn, Moon Ryul;Choi, Jihoon
    • Korean Journal of Materials Research
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    • v.32 no.6
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    • pp.307-312
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    • 2022
  • Metal halide perovskite (MHP) nanocrystals (NCs) have emerged as promising materials for various optoelectronic applications including photovoltaics, light-emitting devices, and photodetectors because of their high absorption coefficient, high diffusion length, and photoluminescence quantum yield. However, understanding the morphological evolution of the MHP NCs as well as their controlled assembly into optoelectronic devices is still challenging and will require further investigation of the colloidal chemistry. In this study, we found that the amount of n-octylamine (the capping agent) plays a crucial role in inducing further growth of the MHP NCs into one-dimensional nanowires during the aging process. In addition, we demonstrate that the dielectrophoresis process can permit self-alignment of the MHP nanowires with uniform distribution and orientation on interdigitated electrodes. A strong light-matter interaction in the MHP NWs array was observed under UV illumination, indicating the photo-induced activation of their luminescence and electrical current in the self-aligned MHP nanowire arrays.