• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(I)
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• pp.490-496
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• 2002

This paper presents exact Autotransformers(ATs)-fed AC electric Railroad system modeling using constant current mode far locomotives. An AC electric railroad system is rapidly changing single-phase load, and at a feeding substation, 3-phase electric power is transferred to paired directional single-phase electric power. As the train moves along a section of line between two adjacent ATs. The proposed AC electric railroad system modeling method considers the line self-impedances and mutual-impedances. The constant current mode model objectives are to calculate the catenary and rail voltages with the loop equation. When there are more than one train in the AC electric railroad system, the principle of superposition applies and the only difference between the system analyses for one train. Finally, this paper shows the general equation of an AC electric railroad system, and that equation has no relation with trains number, trains position, and feeding distance.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.205-208
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• 2006

The use of Fiber Reinforced Polymer (FRP) bars has been gaining popularity in the civil engineering community, as an alternative material to steel reinforcement, for their noncorrosive nature and high strength-to-weight ratio. Good performance of reinforced concrete requires adequate interfacial bond between the reinforcing material and the concrete because the load applied must be transferred from the matrix to the reinforcement. Although studies on the FRP bond behavior under monotonic loading has been reported by many, there are very little work done under cyclic loading. In this paper, we present the experimental study on the bond behavior of three different types of FRP rebars subjected to four different cyclic loading conditions.

• 대한전기학회논문지:전력기술부문A
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• 제52권9호
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• pp.493-499
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• 2003

This paper presents exact Autotransformers(ATs)-fed AC electric Railroad system modeling using constant current mode for locomotives. An AC electric railroad system is rapidly changing single-phase load, and at a feeding substation, 3-phase electric power is transferred to paired directional single-phase electric power. As the train moves along a section of line between two adjacent ATs. The proposed AC electric railroad system modeling method considers the line self-impedances and mutual-impedances. The constant current mode model objectives are to calculate the catenary and rail voltages with the loop equation. When there are more than one train in the AC electric railroad system, the principle of superposition applies and the only difference between the system analyses for one train. Filially, this paper shows the general equation of an AC electric railroad system, and that equation has no relation with trains number, trains position, and feeding distance.

• Journal of Power Electronics
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• 제10권2호
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• pp.125-131
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• 2010

Switched-resonator converters are a new family of soft switching DC-DC converters where the energy is transferred via a resonator. This paper introduces some isolated topologies of this family. The achieved advantages include, load independent soft-switching, self short-circuit protection, and optimization capability due to topology variety. Compared to conventional series-resonant converters, outstanding advantages such as a smaller fewer number of switches and diodes, a smaller transformer, and lower current stresses are achieved. A general synthesis scheme, functional topologies, and essential relations are included. Experimental results from a laboratory prototype confirm the presented theoretical analysis.

• 전력전자학회논문지
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• 제18권5호
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• pp.485-491
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• 2013

A new passive lossless snubber for boost converter based on magnetic coupling is proposed. It is composed of a winding coupled with boost inductor, one snubber inductor, two snubber capacitor and three additional diodes. Especially, the snubber inductor can not only limit the reverse recovery current of output diode but also minimize switch turn-on losses greatly. Moreover, all of the energy stored in the snubber is transferred to the load in the manner of resonance. To confirm the validity of proposed system, theoretical analysis, design consideration, and verification of experimental results are presented.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 추계학술대회 논문집
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• pp.33-34
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• 2016

This paper presents a load sharing method based on the low bandwidth communication (LBC) applied to a DC microgrid in order to balance the state of charge (SOC) of the battery units connected in parallel to the common bus. In this method, SOC of each battery unit is transferred to each other through LBC to calculate average SOC value. After that, droop coefficients of battery units are adjusted according to the difference between SOC of each unit and average SOC value of all batteries in the system. The proposed method can effectively balance the SOC of battery units in charging and discharging duration with a simple low bandwidth communication system.

• Advances in concrete construction
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• 제15권4호
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• pp.287-301
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• 2023

Hockey games attracts many fans around the world. This game requires a specific type of ball and a stick for controlling the motion and trace of the ball. This control of motion involves hitting the ball which is a direct intensive dynamic loading. The impact load transferred directly to the hand of the player and in the professional player may cause long term medical problems. Therefore, dynamic motion of the stick should be understood. In the current study, we analyze the dynamic motion of a hockey stick under impact loading from a hockey ball. In doing so, the stick geometry is simplified as a beam structure and quasi-2D relations of displacement is applied along with classical linear elasticity theory for isotropic materials. The governing equations and natural boundary condition are extracted using Hamilton's principle. The final equations in terms of displacement components are solved using Galerkin's numerical method. The results are presented using indentation and contact force values for variations of different parameters.

• Structural Engineering and Mechanics
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• 제88권6호
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• pp.609-623
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• 2023

The objective of this study is to investigate the distribution of von Mises stress, peeling stress, and shear stress in the adhesive layer used to bond two composite panels, considering various parameters using a three-dimensional finite element method. The stiffness of the materials and the effect of the stacking order on the amount of load transferred to the adhesive layer were examined to determine which type of laminate generates less stress at the bond line. The study analyzed six different stacking sequences, all with a common first layer in contact with the adhesive and a 0° orientation. Additionally, the impact of using hybrid composites on reducing bond line stress was investigated.

• Wind and Structures
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• 제38권4호
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• pp.325-339
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• 2024

The longitudinal force resulting from tornado loads on transmission line is considered a crucial factor contributing to the failure of transmission line structures during tornado events. Accurate estimation of this longitudinal force poses a challenge for structural designers. Therefore, the objective of this paper is to provide a set of charts that can be easily used to estimate the peak longitudinal forces transferred from the conductors to a tower. The critical wind field and corresponding configuration considered in this paper are previously studied and determined. The charts should account for all the conductor parameters that can affect the value of the longitudinal force. In order to achieve that, a parametric study is first conducted to assess the variation of the longitudinal forces with different conductor parameters, based on the critical tornado configuration. Results of this parametric study are used to develop the charts that can be used to calculate longitudinal forces by adopting a multi-variable line regression. The forces calculated from charts are validated by finite element analysis. An example for the usage of the charts is provided at the end of this paper.

• 대한조선학회논문집
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• 제49권2호
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• pp.132-145
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• 2012

Mooring fittings mean various devices and fittings to safely fasten vessels to quays, jetties and sea-floating buoys, etc. They include mooing winches, capstans, chocks, fairleads, guide rollers, bollards, and bitts. Not only the seats and reinforced parts for the installation of fittings but also ropes and chains for mooring and chain stoppers can be also considered. Because of damages to mooring fittings during mooring directly related to large-scale accidents such as the drifting of vessels, mooring fittings with strength appropriate for the physical features of the vessels must be installed. The reinforcement of the vessels on which the mooring fittings are installed must be designed to withstand the loads transferred from the fittings as well. Also mooring fittings with efficient strength should be required because damaged ships lead to sea pollution such as oil or fuel oil spillage. This study has been performed by the Finite Element Method for two aspects of closed chocks which are divided into structure-supporting shapes and working load. In the case of structure-supporting shapes, they have been performed in the field of sheet and bulwark. As for working load, it has been analyzed according to working load direction such as chock's side and below. At first, strength analysis for unique closed chocks has been carried out by using the Finite Element Method, they are applied for the situation when vessels pass by the panama canal. And then the experiment has been done to verify the analyzed date obtained by FEM. The experimental results were found to be similar to the numerical results with up to 16% difference. On the basis of the results obtained, standardization has been carried out by the Finite Element Method for various sizes of closed chocks.