• Title/Summary/Keyword: size effect model

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The Heterogeneity of Job Creation and Destruction in Transition and Non-transition Developing Countries: The Effects of Firm Size, Age and Ownership

  • Ochieng, Haggai Kennedy;Park, Bokyeong
    • East Asian Economic Review
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    • v.21 no.4
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    • pp.385-432
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    • 2017
  • This paper investigates how firm age, size and ownership are related with job creation and destruction, and how these patterns differ across transition and non-transition economies. The analysis finds that age is inversely related with gross job creation and net job creation in the two samples. This finding is consistent with the theory of the learning effect. The relationship between age and job destruction is indifferent in non-transition economies. On the contrary, old firms in transition economies destroy more jobs than young ones. The paper further establishes an inverse relationship between size and gross job creation in the two groups. However, there is divergence between the two samples; small firms in non-transition economies also exhibit a higher gross job destruction rate. Consequently large firms have a higher net job creation rate. In transition economies, small and large firms exhibit similar rates of job destruction. But small firms retain a higher net job creation rate. A more intriguing finding is that state owned firms do not underperform domestic private ones. This means these countries may be using soft budget constraint which allows state owned firms to overstaff. Finally, crowding out of SMEs by foreign owned firms is not evident in transition economies.

Effects of Clearance on the Formation of Adiabatic Shear Band in Stepped Specimen (계단시편의 간극이 단열전단밴드의 형성에 미치는 영향)

  • Yoo, Y.H.;Jeon, G.Y.;Chung, D.T.
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.7 s.94
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    • pp.1700-1709
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    • 1993
  • The stepped specimen which is subjected to step loading is modeled to study the initiation and growth of adiabatic shear band using explicit time integration finite element method. Three different clearance sizes are tested. The material model for the stepped specimen includes effects of strain hardening, strain rate hardening and thermal softening. It is found that the material inside the fully grown adiabatic shear band experiences three phase of deformation, (1) homogeneous deformation phase, (2) initiation/incubation phase, and (3) fast growth phase. The second phase of deformation is initiated after sudden shear stress drop which occurs at the same time regardless of the clearance size. The incubation time prior to fast growth phase increases, as the clearance size of the stepped specimen increases. Whereas, after incubation period, the growth rate of the adiabatic shear band decreases, as the clearance size decreases. It is also found that two adiabatic shear band may develop instead of one for the smaller clearance size.

The Influence of Corporate Governance on Dividend Decisions of Listed Firms: Evidence from Sri Lanka

  • NAZAR, Mohamed Cassim Abdul
    • The Journal of Asian Finance, Economics and Business
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    • v.8 no.2
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    • pp.289-295
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    • 2021
  • This study investigates the role of corporate governance in the dividend decision of 198 non-financial companies listed on the Colombo Stock Exchange of Sri Lanka, over the period from 2009 to 2016. Four corporate governance indicators are used in this study; managerial ownership, the board size, board independence, and CEO duality. Furthermore, this study considers three control variables such as profitability, firm size, and corporate tax. This study employed the Generalized Method of Moments (GMM) model to estimate the regression models on panel data study. The major contribution of this study is exploring the insight into the effect of corporate governance factors on dividend decisions. The results of the study revealed that managerial ownership showed a significant positive impact on the dividend payout ratio. Board size showed a significant positive influence on the dividend payout ratio. Board independence negatively but significantly influenced the dividend payout ratio. CEO duality showed an insignificant negative impact on the dividend payout ratio. In the framework of these CG indicators, Sri Lankan listed firms are recommended to have dispersed ownerships, large Board size and maintain a balance of power and authority by separating the individual who is assuming the position of the CEO from the Chairperson of the Board and maintain at least two independent directors.

NUMERICAL ANALYSIS FOR FLOW CHARACTERISTICS WITH GEOMETRIC SHAPE AND CONTROL CONDITIONS IN SUBSEA BY-PASS VALVE (심해저 바이패스 밸브의 기하학적 형상과 제어조건에 따른 유동특성에 관한 수치해석적 연구)

  • Lee, J.H.;Min, C.H.;Oh, J.W.;Cho, S.;Kim, H.W.
    • Journal of computational fluids engineering
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    • v.21 no.2
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    • pp.99-105
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    • 2016
  • The present study has been carried out to analyze the flow characteristics with geometric shape and control conditions in subsea by-pass valve. The function of by-pass valve is to prevent reverse flow. In this study, the static analysis has been perform for analyzing fluid flow in open state. In order to consider the turbulent effect, the standard ${\kappa}-{\varepsilon}$ model was used. A variety of parametric studies, such as by-pass valve type or size, volume flow rate, leakage hole size, leakage hole position, block type, block shape, were performed. The pressure difference across the valve in the model broadened the flow channel cross-sectional area was greater than the base model for the same operating conditions. As the pipe diameter in the block decreases the pressure difference is greatly increased. The pressure difference according to block shape such as edge type and round was almost negligible. For the same Reynolds number the pressure difference was little changed according to the size of the valve.

Preparation of Polycaprolactone Microcapsules by Membrane Emulsification Method and Its Drug Release Properties (막유화법에 의한 생분해성 Polycaprolactone 마이크로캡슐의 제조와 약물방출 특성)

  • Youm, Kyung-Ho;Yun, Tae-Ho;Kim, Kong-Soo;Cho, Suh-Hyeong
    • Membrane Journal
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    • v.17 no.1
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    • pp.67-79
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    • 2007
  • Uniform microcapsules containing ionic model drugs were prepared by controlling various conditions of emulsification procedure using a lab-scale membrane emulsification system with a SPG (Shirasu porous glass) tubular membrane. We observed the effects of various emulsification parameters [concentration and molecular weight of polycaprolatone (PCL) polymer, transmembrane pressure and emulsifier concentration in disperse phase and continuous phase, stirring speed] on the mean size and size ditribution of microcapsules containing lidocaine hydrochloride (cationic drug), sodium salicylate (nonionic drug) and 4-acetaminophen (anionic drug) used as a model drugs. Also, release characteristics of a model drugs from PCL microcapsules were investigated. Controlling membrane emulsification parameters, uniform PCL microcapsules with about $5\;{\mu}m$ of the mean size were finally prepared. The release rate and the burst effect of microcapsules were decreased in condition of the acidic solution, but it was increased in condition of the base solution.

The Effects of Volume Ratio and Shape on the Formation of Adiabatic Shear Band in WHA (텅스텐 중합금의 부피분율, 입자형상에 따른 단열전단밴드 형성 연구)

  • 이승우;송흥섭;문갑태
    • Transactions of Materials Processing
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    • v.11 no.8
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    • pp.682-690
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    • 2002
  • The formation of adiabatic shearband in tungsten heavy alloys(WHA) was studied in this investigation. Five prismatic specimens were loaded by high velocity impacts and treated as plane strain problems. To find out the effect of particle's volume ratio, specimens containing 81%, 93% and 97% volume percents of tungsten particles were used. Also the effects of particle's geometry and size on the formation of shearband were studied for 81% volume percent alloys by small size particle model, large size particle model and undulated particle models, and the results were discussed.be used to diagnose the causes of necking and fracture in industrial practice and to investigate whether these defects were caused by material property variation, changes in lubrication, or incorrect press settings. In non-axisymmetric deep drawing, three modes of forming regimes are found: draw, stretch, plane strain. The stretch mode for non-axisymmetric deep drawing could be defined when the major and minor strains are positive. The draw mode could be defined when the major strain is positive and minor strain is negative, and plane strain mode could be defined when the major strain is positive and minor strain is zero. Through experiments the draw mode was shown on the wall and flange are one of a drawn cup, while the plane strain and the stretch mode were on the punch head and the punch corner area respectively, We observed that the punch load of elliptical deep drawing was decreased according to increase of die corner radius and the thickness deformation of minor side was more large than major side.

On the mechanics of nanocomposites reinforced by wavy/defected/aggregated nanotubes

  • Heidari, Farshad;Taheri, Keivan;Sheybani, Mehrdad;Janghorban, Maziar;Tounsi, Abdelouahed
    • Steel and Composite Structures
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    • v.38 no.5
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    • pp.533-545
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    • 2021
  • What is desirable in engineering is to bring the engineering model as close to reality as possible while the simplicity of model is also considered. In recent years, several studies have been performed on nanocomposites but some of these studies are somewhat far from reality. For example, in many of these studies, the carbon nanotubes (CNTs) are assumed completely straight, flawless and uniformly distributed throughout the matrix but by studying nanocomposites, we find that this is not the case. In this paper, three steps have been taken to bring the presented models for nanocomposites closer to reality. One is that assuming the straightness of nanotubes is removed and the waviness is considered. Also, the nanotubes are not considered to be pristine and the influence of defect is included in accordance with reality. In addition, the approximation of uniform distribution of nanotubes is ignored and according to experimental observations, the effect of nanotube aggregation is considered. As far as we know, this is the first study on these three topics together in an article. Moreover, we also include the size effects in our models for nanocomposites. To show the accuracy of our models, our results are calibrated with experimental results and compared with theoretical model. For numerical examples, we present the buckling behaviors of nanocomposites including the size effects using nonlocal theory and compare the results of our models with the results of models with above-mentioned approximations.

The Effect of Molecular Size and Degree of Phosphorylation on the Emulsion Stability of Microcrystalline Chitin (Chitin의 분자량과 Phosphorylation 정도가 Microcrystalline Chitin의 유화안정 능력에 미치는 영향)

  • Lee, Young-Chun;Im, Ji-Soon
    • Korean Journal of Food Science and Technology
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    • v.28 no.6
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    • pp.1009-1013
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    • 1996
  • This study was carried to investigate the emulsion stability of microcrystalline chitins (MCC) prepared from chitins of different molecular sizes and different degrees of phosphorylation in a model fatty food system. Chitins of low, medium and high molecular size prepared from crabshells were phosphorylated to 30-50% to make MCC. MCC prepared from chitin of medium molecular size revealed a high emulsion stability. The best emulsion stability was observed in MCC prepared from medium size chitin with 40% phosphorylation (M-40-MCC). The fat binding capacity of MCC was not significantly different among the samples. MCC with 50% phosphorylation had more fat binding capacity, ranging from 650-690%. When 2.46% of M-40-MCC was applied to a coconutoil-water system as an emulsifier, emulsion separation was observed from 10 min after emulsification, indicating that it could not be used as a sole emulsifier. When 50% of emulsifier (Span-60 &Tween-60) in a liquid coffee creamer, selected as a model fatty foods, was replaced by M-40-MCC, emulsion stability was as good as control. Consistency of liquid creamer was decreased and L value increased as the amount of MCC repacement increased. A liquid creamer with 50% emulsifier replaced by MCC had sensory characteristics equivalent to control.

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Analysis of Particle Deposition onto a Heated or Cooled, Horizontal Free-Standing Wafer Surface (가열 또는 냉각되는 수평웨이퍼 표면으로의 입자침착에 관한 해석)

  • 유경훈;오명도;명현국
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.5
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    • pp.1319-1332
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    • 1995
  • Numerical analysis was performed to characterize the particle deposition behavior on a horizontal free-standing wafer with thermophoretic effect under the turbulent flow field. A low Reynolds number k-.epsilon. turbulence model was used to analyze the turbulent flow field around the wafer, and the temperature field for the calculation of the thermophoretic effect was predicted from the energy equation introducing the eddy diffusivity concept. The deposition mechanisms considered were convection, diffusion, sedimentation, turbulence and thermophoresis. For both the upper and lower surfaces of the wafer, the averaged particle deposition velocities and their radial distributions were calculated and compared with the laminar flow results and available experimental data. It was shown by the calculated averaged particle deposition velocities on the upper surface of the wafer that the deposition-free zone, where the deposition velocite is lower than 10$^{-5}$ cm/s, exists between 0.096 .mu.m and 1.6 .mu.m through the influence of thermophoresis with positive temperature difference of 10 K between the wafer and the ambient air. As for the calsulated local deposition velocities, for small particle sizes d$_{p}$<0.05 .mu.m, the deposition velocity is higher at the center of the wafer than at the wafer edge, whereas for particle size of d$_{p}$ = 2.0 .mu.m the deposition takes place mainly on the inside area of the wafer. Finally, an approximate model for calculating the deposition velocities was recommended and the calculated deposition velocity results were compared with the present numerical solutions, those of Schmidt et al.'s model and the experimental data of Opiolka et al.. It is shown by the comparison that the results of the recommended model agree better with the numerical solutions and Opiolka et al.'s data than those of Schmidt's simple model.

Behavior of the Ground in Obliquely Crossed area Due to Tunnel Excavation Under the Existing Tunnel (기존터널에 근접하여 경사로 교차되는 하부터널굴착에 따른 교차부지반의 거동)

  • Kim, Dong-Gab;Lee, Sang-Duk
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.7 no.4
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    • pp.285-294
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    • 2005
  • The behaviors of the ground in crossed zone and the existing upper tunnel in shallow cover due to the excavation of new lower tunnel crossed to that was studied. Model test was performed in the large scale test pit, the size was '$4.0m(width){\times}3.8m(height){\times}4.1m(length)$'. Test ground was constructed uniformly by sand in middle density and test with the crossed angle of $56^{\circ}$ (obliquely) were performed. The numerical analysis was performed on equal condition with model test. Results of the study by model test and numerical analysis show that earth pressure and settlement of the ground in crossed zone were redistributed due to the longitudinal arching effect by the excavation of lower tunnel. Model test shows that upper tunnel blocks stress flow due to the longitudinal arching effect by excavation of lower tunnel.

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