• Journal of the Korean Society for Railway
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• v.15 no.3
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• pp.237-243
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• 2012

In this paper, a magnetic analysis of SRM(Switched Reluctance Motor) using 3d finite element method considering end-coil effect is presented. SRM models with different stator pole shapes are taken into consideration for the analysis of magnetic characteristics. It is observed that a stator pole shape model having a pole shoe depth is the most suitable one for railway traction application because it gives an improved inductance and torque characteristic. For a speed control of SRM, the PI and sliding mode controllers are applied to designed SRM with magnetic characteristic data obtained from the magnetic analysis. The simulations are carried out using Matlab-Simulink and the control performance is analyzed. By employing the sliding mode controller, the transient response as well as the steady-state error are much improved under a load variation of railway resistance under operation.

• Journal of Magnetics
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• v.20 no.1
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• pp.79-85
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• 2015

This paper presents a comparative study of a Tubular Linear Machine (TLM) with an Axially Magnetized Single-sided Permanent Magnet (AMSPM) and an Axially Magnetized Double-sided Permanent Magnet (AMDPM) based on analytical field calculations. Using a two-dimensional (2-D) polar coordinate system and a magnetic vector potential, analytical solutions for the flux density produced by the stator windings are derived. This technique is significant for the design and control implementation of electromagnetic machines. The field solution is obtained by solving Maxwell's equations in the simplified boundary value problem consisting of the air gap and coil. These analytical solutions are then used to estimate the self and mutual inductances. Two different types of machine are used to verify the validity of these model simplifications, and the analytical results are compared to results obtained using the finite element method (FEM) and experimental measurement.

• Journal of Magnetics
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• v.20 no.1
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• pp.69-78
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• 2015

This paper focuses on the design of a flux-biased rotary electromagnetic actuator with compact structure for fast steering mirror (FSM). The actuator has high force density and its torque output shows linear dependence on both excitation current and rotation angle. Benefiting from a new electromagnetic topology, no additional axial force is generated and an armature with small moment of inertia is achieved. To improve modeling accuracy, the actuator is modeled with flux leakage taken into account. In order to achieve an FSM with good performance, a design methodology is presented. The methodology aims to achieve a balance between torque output, torque density and required coil magnetomotive force. By using the design methodology, the actuator which will be used to drive our FSM is achieved. The finite element simulation results validate the design results, along with the concept design, magnetic analysis and torque output model.

• Journal of IKEEE
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• v.23 no.1
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• pp.224-229
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• 2019

Seat of automobile is required to support the comfort to driver and passenger during the driving. The control method of the seat position is changed from manual type to power type, which means using the motor to increase the comfort of the driver. By using the motor, several problems, such as vibration, noise, and over-current, appeared. These problems can be reduced through the control of seat motor. In this study, a control technology of four control variables, which determine profile of the input voltage applying to the seat motor, is proposed to generate the current profile having soft-start and soft-stop. The current flowing through the coil by input voltage is described by mathematical modeling of power seat. It is confirmed that optimized current profile having soft-start and soft-stop can be generated from simulation using the mathematical model.

• Genomics & Informatics
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• v.19 no.4
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• pp.43.1-43.12
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• 2021

Campylobacter jejuni is one of the most prevalent organisms associated with foodborne illness across the globe causing campylobacteriosis and gastritis. Many proteins of C. jejuni are still unidentified. The purpose of this study was to determine the structure and function of a non-annotated hypothetical protein (HP) from C. jejuni. A number of properties like physiochemical characteristics, 3D structure, and functional annotation of the HP (accession No. CAG2129885.1) were predicted using various bioinformatics tools followed by further validation and quality assessment. Moreover, the protein-protein interactions and active site were obtained from the STRING and CASTp server, respectively. The hypothesized protein possesses various characteristics including an acidic pH, thermal stability, water solubility, and cytoplasmic distribution. While alpha-helix and random coil structures are the most prominent structural components of this protein, most of it is formed of helices and coils. Along with expected quality, the 3D model has been found to be novel. This study has identified the potential role of the HP in 2-methylcitric acid cycle and propionate catabolism. Furthermore, protein-protein interactions revealed several significant functional partners. The in-silico characterization of this protein will assist to understand its molecular mechanism of action better. The methodology of this study would also serve as the basis for additional research into proteomic and genomic data for functional potential identification.

• Advances in nano research
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• v.14 no.1
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• pp.27-43
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• 2023

This article investigates the energy harvesting characteristics of a magneto-electro-elastic (MEE) cantilever beam reinforced with carbon nanotubes (CNT) under transverse vibration. To this end, the well-known lumped parameter model is used to represent the coupled multiphysics problem mathematically. The proposed system consists of the MEE-CNT layer on top and an inactive substrate layer at the bottom. The substrate is considered to be made of either an isotropic or composite material. Basic laws such as Gauss's Law, Newton's Law and Faraday's Law are used to arrive at the governing equations. Surface electrodes across the beam are used to harvest the electric potential produced, together with a wound coil, for the generated magnetic potential. The influence of various distributions of the CNT and its volume fraction, substrate material, length-to-thickness ratio, and thickness ratio of substrate to MEE layer on the energy harvesting behaviour is thoroughly discussed. Further, the effect of external resistances and changes in substrate material on the response is analysed and reported. The article aims to explore smart material-based energy harvesting systems, focusing on their behaviour when reinforced with carbon nanotubes. The results of this study may lead to an improved understanding of the design and analysis of CNT-based smart structures.

• Journal of Applied Reliability
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• v.15 no.4
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• pp.241-247
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• 2015

Purpose : The demand for higher fuel economy vehicles has helped develop fuel-efficient vehicles such as a CVVL called continuous variable valve lift. Existing CVVL has been applying DC type motor to control intake valve, but recently some car parts manufacturers have been developing a BLDC type CVVL motor for improvements of endurance performance. The purpose of this study is to find the potential failure mechanism of the CVVL BLDC moto in early stage of development based on the design properties and design the accelerated life test model. Methods : CVVL BLDC is consist of brushs, coil, magnetic, PCB, bearing and so on. Each component has a latent failure mechanism caused by temperature, humidity, vibration. By analysis result of the failure mechanism, thermal fatigue is the most important factor of a durability of CVVL BLDC motor. So, we designed a new accelerated life test model for guarantee of the CVVL BLDC motor. Results : A crack occurred on via hole in test using the conditions we designed, so we did change the design to avoid this failure. The via hole dimension is changed a little larger, as a result we achieve improvements in reliability of the CVVL BLDC motor. By applying various kinds and extreme level of stresses, we can find the operating limits of products. Conclusion : In thesis, We analyzed the failure mechanism of CVVL BLDC and designed an accelerated life test method to give a guarantee for reliability. Based on the test results, we could improve the reliability of developments by change of design.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.2
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• pp.237-244
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• 2016

Helical compression springs have been widely used in industries. The springs should be verified through experiment whether the inherent characteristics of the spring can be maintained during the manufacturing process. Considerable time and expense is spent in the manufacturing process. Therefore, in this study, the structural integrity evaluation of a spring was conducted using linear static structural analysis. Verification and comparison of the experimental data were carried out using a variety of international industrial standards with the intent to prove the validity of this study. The spring model did not consider coil ends. As a result of conducting the structural analysis, the quality of the mesh was improved and the time needed to create an analytical model was reduced. The study indicated that Poisson's ratio had little influence on the result of the structural analysis. Additionally, the possibility of verifying the structural integrity evaluation by structural analysis was confirmed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.3
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• pp.35-43
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• 2007

In this paper, the inductive power collector using electromagnetic induction for vehicle such as the PRT(Personal Rapid Transit) system is suggested and son ideas for power collector design to improve tile power transfer performance are presented. And also, the analysis of the inductive power transfer system in conjunction with series resonant converter operating variable high frequency is shown. Of particular interest is the sensitivity of the complete system to variations in operational frequency and parameters. In inductive power transfer system electrical power is transferred from a primary winding in the form of a coil or tract to one or more isolated pick-up coils that my relative to the primary. The ability to transmit power without contact enables high reliability and easy maintenance that allows inductive power transfer system to be implemented in hostile environments. This technology has found application in many fields such as electric vehicles, PRT(Personal Rapid Transit) etc. But, low output power is generated due to a loosely coupled characteristic of the large air-gap. Therefore, we will show you various characteristic of inductive power transfer system as double layer construction of secondary winding, which was divided in half to increase both output current and output voltage, a model of power collector and parallel winding structure, a model of concentration/ decentralization winding and the effects of parameter and operational frequency variation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.12
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• pp.954-963
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• 2017

In this paper, we analyzed the electric/magnetic field distribution and SAR distribution in a human body due to the resonant-type wireless power transfer(WPT) system with an operating frequency of 6.78 MHz. To analyze the field distribution under the unperturbed condition, a prototype system was fabricated and the measured results were compared with the simulation results. For safety during measurement, the available power to the transmitter coil is limited to 1 W. To analyze the induced current density and SAR distribution, a simple human model consisting of three layers, skin, fat, and muscle, was used for the simulation. The electromagnetic wave exposure levels obtained through measurement and simulation were compared with the recommended levels by the ICNIRP.