• Journal of the Society of Naval Architects of Korea
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• v.31 no.4
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• pp.82-98
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• 1994

A mathematical model for the hydrodynamic forces acting on the ship manoeuvring in waves is formulated and a numerical method for the problem is developed. The motion of a ship, which manoeuvres in waves, may be thought to have two components; one is a high frequency component due to encounter waves, and the other is a low frequency component due to manoeuvring motion. So the method of two time scale expansion is used to divide linear boundary value problem. For the effects of waves on the manoeuvring motion of a ship, only the second order drift forces are considered. The integral equation for the velocity potential is solved by 3 dimensional panel method and hydrodynamic forces are calculated by direct integral method.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.25 no.4
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• pp.196-220
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• 2021

This study formulates a new geometric parameterization scheme to effectively address numerical analysis subject to the variation of the fiber radius of a square unit cell. In particular, the proposed mesh-morphing approach may lead to a parameterized weak form whose bilinear and linear forms are affine in the geometric parameter of interest, i.e. the fiber radius. As a result, we may certify the reduced basis analysis of a square unit cell model for any parameters in a predetermined parameter domain with a rigorous a posteriori error bound. To demonstrate the utility of the proposed geometric parameterization, we consider a two-dimensional, steady-state heat conduction analysis dependent on two parameters: a fiber radius and a thermal conductivity. For rapid yet rigorous a posteriori error evaluation, we estimate a lower bound of a coercivity constant via the min-θ method as well as the successive constraint method. Compared to the corresponding finite element analysis, the constructed reduced basis analysis may yield nearly the same solution at a computational speed about 29 times faster on average. In conclusion, the proposed geometric parameterization scheme is conducive for accurate yet efficient reduced basis analysis.

• Journal of Ocean Engineering and Technology
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• v.33 no.2
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• pp.106-115
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• 2019

The interaction between a sloshing liquid damper (SLD) tank and a rectangular pontoon was investigated under the assumption of the linear potential theory. The eigenfunction expansion method was used not only for the sloshing problem in the SLD tank but also for analyzing the motion responses of a rectangular pontoon in waves. If the frictional damping due to the viscosity of the SLD tank was ignored, the effect of the SLD appeared to be an added mass in the coupled equation of motion. The installation of the SLD tank had a greater effect on the roll motion response than the sway and heave motion of the pontoon. One resonance peak for rolling motion showed up in the case of a frozen liquid in the SLD tank. However, if liquid motion in the SLD tank was allowed, two peaks appeared around the first natural frequency of the fluid in the SLD tank. In particular, the peak value located in the low-frequency region had a relatively large value, and the peak frequency located in the high-frequency region moved into the high-frequency region as the depth of the liquid in the tank increased.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.1
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• pp.471-478
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• 2021

This study aims to investigate the determinants of turnover intention among company managers in Indonesia. Based on the literature, this research hypothesizes that job satisfaction is a mediator in the relationship between compensation, career and turnover intention of companies in Indonesia. Respondents as research samples are grouped into middle managers from two industries, namely, manufacturing and services. A total of 215 questionnaires were returned from middle managers. Data analysis used Structural Equation Model - Linear Structural Relationship (SEM LISREL). The research results prove that compensation and career have a positive effect on job satisfaction. Compensation, career, and job satisfaction have a negative impact on turnover intention. Compensation is known to be one of the motivating drivers of workers around the world. From this study it can be said that, if middle manager teachers are well compensated, they will be encouraged, persuaded and will have positive feelings toward their work, and this will result in staying put. It works also with career and job satisfaction. If both variables are considered carefully, intention to move tends to be low. These findings provide new insights into the field of international human resources in developing multinational companies and service businesses.

• Structural Engineering and Mechanics
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• v.85 no.6
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• pp.729-742
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• 2023

It is a recent attraction to the mechanical scientists to investigate state of wave propagation, buckling and vibration in the sport balls to observe the importance of different parameters on the performance of the players and the quality of game. Therefore, in the present study, we aim to investigate the wave propagation in handball game ball in term of mass of the ball and geometrical parameters wit incorporation of the viscoelastic effects of the ball material into account. In this regard, the ball is modeled using thick shell structure and classical elasticity models is utilized to obtain the equation of motion via Hamilton's principle. The displacement field of the ball model is obtained using first order shear deformation theory. The resultant equations are solved with the aid of generalized differential quadrature method. The results show that mass of the ball and viscoelastic coefficient have considerable influence on the state of wave propagation in the ball shell structure.

• Asia Marketing Journal
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• v.18 no.2
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• pp.45-61
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• 2016

Book adaptation has been considered an effective strategy in filmmaking. This paper examines the relationship between the box office sales and the performance of its original book focusing on category extension, especially investigating reciprocal spillover effect from a movie to the book. With empirical data, two-way causality between performance of the extension brand (i.e., movies) and that of the parent brand (i.e., books) was examined to test the existence of reciprocal spillover effect. In addition, a linear model was used to test the moderating roles of extension characteristics. The results revealed that the higher the movie's box office sales, the higher the original book's sales after movie's release. The authors also found moderation effects such that if the book has high level of brand awareness prior to movie's release, or if there is a movie tie-in version, or when the book is mentioned in movie trailer, or if the movie is released shortly after the book's publication, then the strength of spillover effect is superior. The current empirical investigation is meaningful considering it provides implications to both buyers and sellers of the extension rights, contributing to the literature of reciprocal spillover effects in category extension.

• Earthquakes and Structures
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• v.25 no.6
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• pp.443-454
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• 2023

Steel shear walls are used to strengthen steel and concrete structures. One such system is Partial Attached Steel Shear Walls (PASSW), which are only connected to frame beams. This system offers both structural and architectural advantages. This study first calibrated the numerical model of RC frames with and without PASSW using an experimental sample. The seismic performance of the RC frame was evaluated by 30 non-linear static analyses, which considered stiffness, ductility, lateral strength, and energy dissipation, to investigate the effect of PASSW width and column axial load. Based on numerical results and a curve fitting technique, a lateral stiffness equation was developed for frames equipped with PASSW. The effect of the shear wall location on the concrete frame was evaluated through eight analyses. Nonlinear dynamic analysis was performed to investigate the effect of the shear wall on maximum frame displacement using three earthquake records. The results revealed that if PASSW is designed with appropriate stiffness, it can increase the energy dissipation and ductility of the frame by 2 and 1.2 times, respectively. The stiffness and strength of the frame are greatly influenced by PASSW, while axial force has the most significant negative impact on energy dissipation. Furthermore, the location of PASSW does not affect the frame's behavior, and it is possible to have large openings in the frame bay.

• Elastomers and Composites
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• v.59 no.1
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• pp.34-41
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• 2024

In this study, the effects of the type and content of silica on the mechanical and tear properties of chloroprene rubber (CR), which is mainly used as a jacket material for mining cables, were studied. The crosslinking density (ΔM) and reinforcing factor (α_f) defined using cure characteristics increased with increasing silica content, whereas the cure rate decreased. The hardness, tensile strength, and modulus of the CR compounds increased depending on the silica content and structural development. The reinforcing behavior of the silica-filled CR compounds according to the silica type and content showed the best fit with the Thomas equation of the predictive model. Tear strength was evaluated using two standard test methods, ASTM D470 and DIN VDE 0472-613, and the results were compared. The tear strength increased as the silica content increased, regardless of the test method, and the different tear strengths obtained by the two standard test methods showed a linear relationship with each other, indicating a high correlation.

• Advances in aircraft and spacecraft science
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• v.11 no.1
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• pp.55-81
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• 2024

This paper presents the exact solutions and closed forms for of nonlinear stability and vibration behaviors of straight and curved beams with nonlinear viscoelastic boundary conditions, for the first time. The mathematical formulations of the beam are expressed based on Euler-Bernoulli beam theory with the von Karman nonlinearity to include the mid-plane stretching. The classical boundary conditions are replaced by nonlinear viscoelastic boundary conditions on both sides, that are presented by three elements (i.e., linear spring, nonlinear spring, and nonlinear damper). The nonlinear integro-differential equation of buckling problem subjected to nonlinear nonhomogeneous boundary conditions is derived and exactly solved to compute nonlinear static response and critical buckling load. The vibration problem is converted to nonlinear eigenvalue problem and solved analytically to calculate the natural frequencies and to predict the corresponding mode shapes. Parametric studies are carried out to depict the effects of nonlinear boundary conditions and amplitude of initial curvature on nonlinear static response and vibration behaviors of curved beam. Numerical results show that the nonlinear boundary conditions have significant effects on the critical buckling load, nonlinear buckling response and natural frequencies of the curved beam. The proposed model can be exploited in analysis of macrosystem (airfoil, flappers and wings) and microsystem (MEMS, nanosensor and nanoactuators).

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.2
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• pp.63-77
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• 2022

Our aim was to reduce estimation errors of a wind velocity model used as an early warning system for weather risk management in the agricultural sector. The Rural Development Administration (RDA) agricultural weather observation network's wind velocity data and its corresponding estimated data from January to December 2020 were used to calculate linear regression equations (Y = aX + b). In each linear regression, the wind estimation error at 87 points and eight time slots per day (00:00, 03:00, 06:00, 09.00, 12.00, 15.00, 18.00, and 21:00) is the dependent variable (Y), while the estimated wind velocity is the independent variable (X). When the correlation coefficient exceeded 0.5, the regression equation was used as the wind velocity correction equation. In contrast, when the correlation coefficient was less than 0.5, the mean error (ME) at the corresponding points and time slots was substituted as the correction value instead of the regression equation. To enable the use of wind velocity model at a national scale, a distribution map with a grid resolution of 250 m was created. This objective was achieved b y performing a spatial interpolation with an inverse distance weighted (IDW) technique using the regression coefficients (a and b), the correlation coefficient (R), and the ME values for the 87 points and eight time slots. Interpolated grid values for 13 weather observation points in rural areas were then extracted. The wind velocity estimation errors for 13 points from January to December 2019 were corrected and compared with the system's values. After correction, the mean ME of the wind velocities reduced from 0.68 m/s to 0.45 m/s, while the mean RMSE reduced from 1.30 m/s to 1.05 m/s. In conclusion, the system's wind velocities were overestimated across all time slots; however, after the correction model was applied, the overestimation reduced in all time slots, except for 15:00. The ME and RMSE improved b y 33% and 19.2%, respectively. In our system, the warning for wind damage risk to crops is driven by the daily maximum wind speed derived from the daily mean wind speed obtained eight times per day. This approach is expected to reduce false alarms within the context of strong wind risk, by reducing the overestimation of wind velocities.