• 대한수학회지
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• 제39권2호
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• pp.319-330
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• 2002

The method of quasilinearization generates a monotone iteration scheme whose iterates converge quadratically to a unique solution of the problem at hand. In this paper, we apply the method to two families of three-point boundary value problems for second order ordinary differential equations: Linear boundary conditions and nonlinear boundary conditions are addressed independently. For linear boundary conditions, an appropriate Green\`s function is constructed. Fer nonlinear boundary conditions, we show that these nonlinearities can be addressed similarly to the nonlinearities in the differential equation.

• 수산해양기술연구
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• 제42권1호
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• pp.44-53
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• 2006

The expansion of near shore aquaculture is feasibility of moving aquaculture facilities into the open ocean. Numerical modeling technique using finite element method was used to enable the optimum design and evaluation of submersible aquaculture cage system. The characteristics of mooring loads response in mooring lines under waves and current and their response amplitude operators were calculated for single and three point mooring configuration at the surface condition and submerged one. The static mooring loads without wave and current loading were similar for both the surface and submerged configuration. It was calculated that three point mooring was more adequate than single point mooring for the mooring configuration of submersible aquaculture cage system. The wave induced response amplitude operators for the single point mooring configuration with the influence of currents were identical to those without the influence of currents.

• 한국해양공학회지
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• 제20권1호
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• pp.43-47
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• 2006

Superposition of three wave trains on finite depth is investigated. This paper is focused on how to improve the linear superposition of three waves. This was realized by introducing the scheme. The idea of the scheme is based on a fixed point approach. Application of the scheme to the superposition makes it possible to obtain a wave profile of wave-wave interaction. With the help of FFT, it was possible to analyze high-order nonlinear frequencies for three interacting Stokes' waves on finite depth.

• Korean Journal of Mathematics
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• 제19권4호
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• pp.481-493
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• 2011

We prove a theorem which shows the existence of at least three ${\pi}$-periodic solutions of the wave equation with asymptotical linearity. We obtain this result by the finite dimensional reduction method which reduces the critical point results of the infinite dimensional space to those of the finite dimensional subspace. We also use the critical point theory and the variational method.

• 한국측량학회지
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• 제37권2호
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• pp.45-53
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• 2019

RGB-D SLAM (Simultaneous Localization and Mapping) refers to the technology of using deep camera as a visual sensor for SLAM. In view of the disadvantages of high cost and indefinite scale in the construction of maps for laser sensors and traditional single and binocular cameras, a method for creating three-dimensional map of indoor environment with deep environment data combined with RGB-D SLAM scheme is studied. The method uses a mobile robot system equipped with a consumer-grade RGB-D sensor (Kinect) to acquire depth data, and then creates indoor three-dimensional point cloud maps in real time through key technologies such as positioning point generation, closed-loop detection, and map construction. The actual field experiment results show that the average error of the point cloud map created by the algorithm is 0.0045m, which ensures the stability of the construction using deep data and can accurately create real-time three-dimensional maps of indoor unknown environment.

• Journal of Advanced Marine Engineering and Technology
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• 제5권1호
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• pp.20-27
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• 1981

The alignment of propulsion shaft systems by the fair curve method has been developed over the past twenty years and in recent years its basic problems have been almost solved. At the present time, studies on introducing actual conditions are being undertaken. In a fair curve alignment, its aim is to achieve a stable shaft system which will be relatively insensitive to misalignment or the influence of external factors such as thermal variations due to the sunshine, speed change, etc. The key point of fair curve alignment is the calculations of reactions in the straight support and reaction influence numbers. The present authors have developed those calculating method by the matrix method of the three-moment theorem. The fair curve alignment is based on the analysis of propulsion shaft system which is assumed as a continous beam on multiple support points. The propeller shaft is divided into several elements. For each element, the nodal point equation is derived by the three-moment theorem. Reaction of supporting points of straight shaft and reaction influence numbers are calculated by the matrix calculation of each nodal point equation. It has been found that results of calculation for the model shaft agree well with those of experiment which had been measured by the strain gauge method. Results of calculation for the actual propulsion shafting of the steam turbine had been compared also with those of Det norske Vertas.

• Geomechanics and Engineering
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• 제20권1호
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• pp.9-18
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• 2020

Three-point bending specimens have been used to investigate the mixed mode fracture of green sandstone. Dimensionless stress intensity factors and T-stresses were calculated first by using the finite element method for various crack lengths, crack angles and span to length ratios. It is shown that three-point bending specimens can provide the whole range of mode mixities from pure mode I to pure mode II, provided suitable values are chosen for the crack angle and span to length ratio. The fracture test results were also used to compare with predictions of different criteria. These comparisons show that modified criteria including the influence of the T-stress agree better with experiment than the conventional criteria but that no one criterion matches perfectly the test results.

• Journal of applied mathematics & informatics
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• 제27권3_4호
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• pp.895-902
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• 2009

In this paper, the singular three-point boundary value problem $$\{{{u"(t)\;+\;f(t,\;u)\;=\;0,\;t\;{\in}\;(0,\;1),}\atop{u(0)\;=\;0,\;u(1)\;=\;{\alpha}u(\eta),}}\$$ is studied, where 0 < $\eta$ < 1, $\alpha$ > 0, f(t,u) may be singular at u = 0. By mixed monotone method, the existence and uniqueness are established for the above singular three-point boundary value problems. The theorems obtained are very general and complement previous know results.

• Journal of Power Electronics
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• 제19권2호
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• pp.560-568
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• 2019

This paper studies the inherent relationship between currents and zero-sequence components. Then a precise algorithm is proposed to calculate the injected zero-sequence component to control the DC-Link neutral-point voltage balance, which can result in a more efficient and flexible neutral point voltage balance with a desirable performance. In addition, it is shown that carried-based PWM with the calculated zero-sequence component scheme can be equivalent to space-vector pulse-width modulation (SVPWM). Based on the proposed method, the optimal zero-sequence component of the feasible modulation indices is analyzed. In addition, the unbalanced load limitation of the DC-Link neutral-point voltage balance control is also revealed. Simulation and experimental results are shown to verify the validity and practicality of the proposed algorithm.

• 전력전자학회논문지
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• 제22권2호
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• pp.150-158
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• 2017

This study proposes a new pulse-width modulation switching pattern for the low conduction loss of a three-level neutral point clamped (NPC)-based dual-active bridge (DAB) converter. The operational principle for a bidirectional power conversion is a phase-shift modulation. The conventional switching method of the three-level NPC-based DAB converter shows a symmetric switching pattern. This method has a disadvantage of high root-mean-square (RMS) value of the coupling inductor current, which leads to high conduction loss. The proposed switching method shows an asymmetrical pattern, which can reduce the RMS value of the inductor current with lower conduction loss than that of the conventional method. The performance of the proposed asymmetrical switching method is theoretically analyzed and practically verified using simulation and experiment.