• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.23-32
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• 2000

The purpose of this study is to identify the dynamic characteristics of a motor-die in washing machine and provide quantitative design information needed for the reduction of radiated sound from the motor-die. To perform the design analysis, dynamic characteristics are identified by motor-die modeling and the availability of model is verified by experimental modal analysis. Numerical approach using MSC/NASTRAN and SYSNOISE predicted sound attenuation effects according to the change of design parameters, such as thickness, concentrated mass and rib. The numerical results due to the rib attachment showed the significant noise attenuation effects over 15dB in the frequency range of 450-700Hz.

• Journal of Information Processing Systems
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• v.15 no.4
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• pp.967-985
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• 2019

Bug report processing is a key element of bug fixing in modern software maintenance. Bug reports are not processed immediately after submission and involve several processes such as bug report deduplication and bug report triage before bug fixing is initiated; however, this method of bug fixing is very inefficient because all these processes are performed manually. Software engineers have persistently highlighted the need to automate these processes, and as a result, many automation techniques have been proposed for bug report processing; however, the accuracy of the existing methods is not satisfactory. Therefore, this study focuses on surveying to improve the accuracy of existing techniques for bug report processing. Reviews of each method proposed in this study consist of a description, used techniques, experiments, and comparison results. The results of this study indicate that research in the field of bug deduplication still lacks and therefore requires numerous studies that integrate clustering and natural language processing. This study further indicates that although all studies in the field of triage are based on machine learning, results of studies on deep learning are still insufficient.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.4
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• pp.523-531
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• 2019

This paper deals with a wound-field synchronous machines(WFSM), with an electromagnet on its salient rotor, as an alternative to a permanent magnet in the rotor. We then examine the power performance characteristics, loss characteristics, V-curves and large short-circuit ratios for a large-scale synchronous generator, considering the leading and lagging operations, based on the finite-element method. We predict the performance of a 100MVA-class generator based on the operating range for a constant short-circuit ratio. At the last, We compared with the electromagnetic characteristics of three model according to number of slots.

• Journal of the Korean Society of Systems Engineering
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• v.16 no.2
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• pp.16-26
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• 2020

Improving operator performance in complex and time-critical situations is critical to maintain plant safety and operability. These situations require quick detection, diagnosis, and mitigation actions to recover from the root cause of failure. One of the key challenges for operators in nuclear power plants is information management and following the control procedures and instructions. Nowadays Digital Twin technology can be used for analyzing and fast detection of failures and transient situations with the recommender system to provide the operator or maintenance engineer with recommended action to be carried out. Systems engineering approach (SE) is used in developing a digital twin for the CEDM system to support operator actions when there is a misalignment in the control element assembly group. Systems engineering is introduced for identifying the requirements, operational concept, and associated verification and validation steps required in the development process. The system developed by using a machine learning algorithm with a text mining technique to extract the required actions from limiting conditions for operations (LCO) or procedures that represent certain tasks.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.848-857
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• 2021

This paper proposes an efficient approach based on a machine learning technique to predict the local stresses on mooring chain links. Three-link and multi-link finite element analyses were conducted for a target chain link of D107 with steel grade R4; 24,000 and 8000 analyses were performed, respectively. Two serial Artificial Neural Network (ANN) models based on a deep multi-layer perceptron technique were developed. The first ANN model corresponds to multi-link analyses, where the input neurons were the tension force and angle and the output neurons were the interlink angles. The second ANN model corresponds to the three-link analyses with the input neurons of the tension force, interlink angle, and the local stress positions, and the output neurons of the local stress. The predicted local stresses for the untrained cases were reliable compared to the numerical simulation results.

• Coupled systems mechanics
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• v.11 no.3
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• pp.259-266
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• 2022

Non-Traditional Optimization methods are successfully used in solving many engineering problems. Shaft is one of important element of machines and it is used to transmit power from a machine which produces power to a machine which absorbs power. In this paper, ten non-traditional optimization methods that are ALO, GWO, DA, FPA, FA, WOA, CSO, PSO, BA and GSA are used to find minimum weight of hollow shaft to get global optimal solution. The problem has two design variables and two inequality constraints. The comparative results show that the Particle Swarm Optimization outperforms other methods and the results are validated using ANSYS.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.3
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• pp.253-257
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• 2005

By using a coupled circuit, time-stepping, two-dimensional finite element method (2-D FEM), the performance of a stand-alone permanent-magnet synchronous generator (PMSG) with inset rotor can be computed without involving the classical two-axis model. The effects of interpolar air gap length and armature resistance on the load characteristics are investigated. It is shown that the interpolar flux density, and hence the amount of voltage compensation, is affected by magnetic saturation. Validity of the coupled circuit and field analysis is confirmed by experiments on a prototype generator. The machine exhibits an approximately level load characteristic when it is supplying an isolated unity-power-factor load.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.857-859
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• 2002

This paper describes an analysis of Magnetic actuator with permanent magnet using 2-D axisymmetric finite element method. Magnetic actuator is the machine to change electrical signal into mechanical signal, and fast switching device to be used for breaker and automation field etc. This magnetic actuator considered action for armature distance, external circuit, and nonlinear material characteristic and current. Also, comparative analysis is performed for 2 coil type and 1 coil type by coil type of actuator, then characteristic is grasped. It is Combined with external circuit for analyzing transient characteristic by variable time. According to the results, we analyzed action characteristic of Magnetic actuator.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.8
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• pp.72-79
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• 2008

To meet demand of big capacity and high speed rotation for washing machine, more stress from bending and twisting are complexly loaded onto the shaft supporting the horizontal drum, causing problems in fracture strength and fatigue life. Shafting system is mainly divided into flange and shaft. Shaft and flange connected by inserting shaft serration into flange on the process of die casting. When the system is operating, the gap is formed between serration and flange. But, Serration has various design factors and the optimal values can't be easily determined. Using a design of experiment (DOE) based on the FEM (Finite Element Method), this study was performed investigating the interaction effect between the various design factors as well as the main effect of the each design factor under bending, twist and vibration and proposed optimum design using box-behnken method among response surface derived from regression equation of simulation-based DOE.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.2
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• pp.26-30
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• 2016

This paper presented an optimum design of a perpendicular PMDSLSM (Permanent Magnet Double-sided Linear Synchronous Motor) to minimize the detent force. As an optimum method, the response surface method was used and 3D finite element method for the calculation. The design variables of the machine were the primary core width and thickness, and magnet width, thickness and length. Object functions were to minimize the detent force and maximize the thrust of the basic model. The results showed that the thrust force of the optimum design increased from 82.1N to 90.2N and detent force decreased from 15.2N to 2.8N, respectively, compared to the basic model.