• Korea Journal of Hospital Management
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• v.11 no.2
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• pp.61-86
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• 2006

Based on a previous literature about hospital capital structure(Shyam- Sunder & Myers, 1999), this study attempted comparison and analysis on whether the forecast of trade-off and pecking order theory could be validated in hospital's capital structure. First, this study analyzed whether hospitals follow the priority for each capital source as suggested by pecking order theory under lack of capital running in hospital. Next, it analyzed whether debt level is regressed on the average to target debt level so as to verify the validity of trade-off theory. Finally, it also analyzed possible associations between debt level and determinants of capital structure as adopted in static trade-off theory, so as to verify relative advantages of these two theories about hospital capital structure. The analysis over whole period showed that both trade-off theory and pecking order theory isn't supported particularly. This mean that each hospital's financing behaviors is different and that has not dominant financing behaviors. In the midst of separation of dispensary from medical practice, medical institutions in Korea first finances funds required using retained earnings and then use liabilities. however pecking order theory is supported, the preference of long-term liabilities and short-term liabilities is not clear. In addition, considering that debt level is in no average regression to target debt ratio, it is found that hospital capital structure following trade-off theory turns into that subject to pecking order theory via the separation of dispensary from medical practice.

• Journal of Korea Port Economic Association
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• v.34 no.2
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• pp.69-82
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• 2018

The number of ships serviced at the container terminals in Busan is increasing by 2.9% per year. In spite of the increase in calling ships, there are no official records of waiting rate by the port authority. This study attempts to compare the theoretical ship waiting ratio and actual ship waiting ratio. The actual ship waiting ratio of container terminals is acquired from the 2014 to 2016 data of PORT-MIS and Terminal Operating System (TOS). Furthermore, methods and procedures to measure the actual ship's waiting rate of container terminal are proposed for ongoing measurement. In drawing the theoretical ship waiting ratio, the queuing theory is applied after deploying the ship arrival probability distribution and ship service probability distribution by the Chi Square method. As a result, the total number of ships waiting in a terminal for three years was 587, the average monthly service time and the average waiting time was 13.8 hours and 17.1 hours, respectively, and the monthly number of waiting ships was 16.3. Meanwhile, according to the queuing theory with multi servers, the ship waiting ratio is 31.1% on a 70% berth occupancy ratio. The reason behind the huge gap is the congested sailing in the peak days of the week, such as Sunday, Tuesday, and Wednesday. In addition, the number of waiting ships recorded on Sundays was twice as much as the average number of waiting ships.

• Smart Structures and Systems
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• v.19 no.2
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• pp.115-126
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• 2017

In this paper, size dependent bending and free flexural vibration behaviors of functionally graded (FG) nanobeams are investigated using a nonlocal quasi-3D theory in which both shear deformation and thickness stretching effects are introduced. The nonlocal elastic behavior is described by the differential constitutive model of Eringen, which enables the present model to become effective in the analysis and design of nanostructures. The present theory incorporates the length scale parameter (nonlocal parameter) which can capture the small scale effect, and furthermore accounts for both shear deformation and thickness stretching effects by virtue of a hyperbolic variation of all displacements through the thickness without using shear correction factor. The material properties of FG nanobeams are assumed to vary through the thickness according to a power law. The neutral surface position for such FG nanobeams is determined and the present theory based on exact neutral surface position is employed here. The governing equations are derived using the principal of minimum total potential energy. The effects of nonlocal parameter, aspect ratio and various material compositions on the static and dynamic responses of the FG nanobeam are discussed in detail. A detailed numerical study is carried out to examine the effect of material gradient index, the nonlocal parameter, the beam aspect ratio on the global response of the FG nanobeam. These findings are important in mechanical design considerations of devices that use carbon nanotubes.

• Advances in nano research
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• v.7 no.3
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• pp.191-208
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• 2019

In the present work the dynamic analysis of the functionally graded rectangular nanoplates is studied. The theory of nonlocal elasticity based on the quasi 3D high shear deformation theory (quasi 3D HSDT) has been employed to determine the natural frequencies of the nanosize FG plate. In HSDT a cubic function is employed in terms of thickness coordinate to introduce the influence of transverse shear deformation and stretching thickness. The theory of nonlocal elasticity is utilized to examine the impact of the small scale on the natural frequency of the FG rectangular nanoplate. The equations of motion are deduced by implementing Hamilton's principle. To demonstrate the accuracy of the proposed method, the calculated results in specific cases are compared and examined with available results in the literature and a good agreement is observed. Finally, the influence of the various parameters such as the nonlocal coefficient, the material indexes, the aspect ratio, and the thickness to length ratio on the dynamic properties of the FG nanoplates is illustrated and discussed in detail.

• The Journal of the Korea Contents Association
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• v.21 no.10
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• pp.368-377
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• 2021

This study analyzed the determinants of capital structure based on the financial statements of agricultural corporations disclosed on the DART(data analysis, retrieval and transfer system) of the Financial Supervisory Service since 2011, when the Korea international financial reporting standards (K-IFRS) was introduced. There have been many empirical studies on the capital structure so far, but there are no studies targeting agricultural corporations. The sample period of agricultural corporations was from 2015 to 2019, with the debt ratio as the dependent variable, and among the variables suggested as meaningful in existing empirical studies, ROA(profitability), SIZE(corporate size), LIQ(liquidity), TA(tangible asset ratio), FA(fixed long-term suitability ratio), and GROWTH(growth potential) were selected as independent variables and panel data analysis was performed. As a result of the analysis, it was found that the debt ratio decreased as the ROA and SIZE of agricultural corporations increased. This can be interpreted as supporting the pecking order theory rather than the static trade-off theory in the relationship between the ROA and SIZE of Korean agricultural corporations with the capital structure. In addition, it was found that the debt ratio increased as the FA increased. These results suggest that Korean agricultural corporations need to establish a financing policy in consideration of ROA, SIZE, and FA.

• Journal of the Korean Geotechnical Society
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• v.26 no.7
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• pp.161-170
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• 2010

For the development of load and resistance factor design, reliability analysis is required to calibrate resistance factors in the framework of reliability theory. The distribution of measured-to-predicted pile resistance ratio was obrained based on only the results of load tests conducted to failure for the assessment of uncertainty regarding pile resistance and used in the conventional reliability analysis. In other words, successful pile load test (piles resisted twice their design loads without failure) results were discarded, and therefore, were not reflected in the reliability analysis. In this paper, a new systematic method based on Bayesian theory is used to update reliability indices of driven steel pipe piles by adding more proof pile load test results, even not conducted to failure, to the prior distribution of pile resistance ratio. Fifty seven static pile load tests performed to failure in Korea were compiled for the construction of prior distribution of pile resistance ratio. The empirical method proposed by Meyerhof is used to calculate the predicted pile resistance. Reliability analyses were performed using the updated distribution of pile resistance ratio. The challenge of this study is that the distribution updates of pile resistance ratio are possible using the load test results even not conducted to failure, and that Bayesian updates are most effective when limited data are available for reliability analysis.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.3
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• pp.273-278
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• 2017

This paper is to study a technique to detect the real-time route aberrance on the passage route using bumper area of the ship domain theory. In order to evaluate the risk of route aberrance, a quarter line was created between the center line and the outer line, and a passage route with the image line outside the outer line was designed. It calculated the real-time route aberrance with the vessel bumper area to measure the risk level on the passage route. The route aberrance using overlap bumper area was simulated through three kinds of scenario vessel at the designed passage route. In this paper, we proposed Ratio to Aberrance Risk as one of the evaluation parameter to detect the route aberrance risk at each sector in the passage route and to give the evaluation criteria of 5 levels for seafarer's navigation safety. The purpose of this work is to provide the information of the route aberrance to seafarer automatically, to make it possible to prevent the human errors of seafarer on the high risk aberrance route. As the real-time risk of route aberrance on the passage route is automatically evaluated, it was well thought that seafarer can have only a little workload in order to know the risk of route aberrance at early-time. Following the further development of this work, the techniques for detecting the real-time route aberrance will be able to use the unmanned vessel.

• Steel and Composite Structures
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• v.24 no.2
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• pp.151-176
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• 2017

This paper deals with general equations of motion for free vibration analysis response of thick three-layer doubly curved sandwich panels (DCSP) under simply supported boundary conditions (BCs) using higher order shear deformation theory. In this model, the face sheets are orthotropic laminated composite that follow the first order shear deformation theory (FSDT) based on Rissners-Mindlin (RM) kinematics field. The core is made of orthotropic material and its in-plane transverse displacements are modeled using the third order of the Taylor's series extension. It provides the potentiality for considering both compressible and incompressible cores. To find these equations and boundary conditions, Hamilton's principle is used. Also, the effect of trapezoidal shape factor for cross-section of curved panel element ($1{\pm}z/R$) is considered. The natural frequency parameters of DCSP are obtained using Galerkin Method. Convergence studies are performed with the appropriate formulas in general form for three-layer sandwich plate, cylindrical and spherical shells (both deep and shallow). The influences of core stiffness, ratio of core to face sheets thickness and radii of curvatures are investigated. Finally, for the first time, an optimum range for the core to face sheet stiffness ratio by considering the existence of in-plane stress which significantly affects the natural frequencies of DCSP are presented.

• Earthquakes and Structures
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• v.10 no.5
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• pp.1033-1048
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• 2016

An analytical solution based on the neutral surface concept is developed to study the free vibration behavior of simply supported functionally graded plate reposed on the elastic foundation by taking into account the effect of transverse shear deformations. No transversal shear correction factors are needed because a correct representation of the transversal shearing strain obtained by using a new refined shear deformation theory. The foundation is described by the Winkler-Pasternak model. The Young's modulus of the plate is assumed to vary continuously through the thickness according to a power law formulation, and the Poisson ratio is held constant. The equation of motion for FG rectangular plates resting on elastic foundation is obtained through Hamilton's principle. Numerical examples are provided to show the effect of foundation stiffness parameters presented for thick to thin plates and for various values of the gradient index, aspect and side to thickness ratio. It was found that the proposed theory predicts the fundamental frequencies very well with the ones available in literature.

• Journal of Korean Society of Steel Construction
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• v.9 no.3 s.32
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• pp.333-340
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• 1997

This paper will expand the third-order shear deformation theory by the double-Fourier series and reduce to the solution of a system of ordinary differential equations in time, which are integrated numerically using Newmark's direct integration method and clarify the undamped dynamic responses for the cross-ply and antisymmetric angle-ply laminated composite plates and shells with simply supported boundary condition. Numerical results for deflections are presented showing the effect of side-to-thickness ratio, aspect ratio, material anisotropy, and lamination scheme.