• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.5
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• pp.892-897
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• 2007

This paper presents the output filter design and the output characteristic analysis by cut-off frequency set up of the LCR filter on NPC multi-level inverter with trap-filter. The single-phase NPC three-level inverter operates at low switching frequency. The proposed LC trap filter is comprised of a conventional LCR output filter, by using LC trap filter the need for high damping resistor and low LC cut-off frequency is eliminated. Also. low damping resistor is increased the output filter system. The multilevel inverter system used NPC type inverter in proper system for high power application and controller is used DSP(TMS320C31). The effectiveness of proposed system confirmed the validity through SPICE simulation and experimental results.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.220-224
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• 2001

High-speed machining is one of the most effective technologies to improve productivity. Because of the high speed and high feedrate, high-speed machining can give great advantages for the machining of dies and molds. To perform efficient high-speed machining, evaluation of high speed machinability must be studied preferentially and it can be identified by investigation of cutting force. To measure cutting force in high-speed machining, dynamometer has to have high natural frequency. In this paper, The dynamometer which has high natural frequency used to measure the cutting force in various cutting conditions. High-speed machining characteristics are evaluated by the cutting force, FFT analysis of the cutting force and chip formation.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.135-138
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• 2009

Most of the studies use model order reduction for low frequency (LF) response analysis due to their high computational efficiency. In LF response analysis, one of model order reduction, algebraic substructuring (AS) retains all LF modes when using the modal superposition. However, in mid-frequency (MF) response analysis, the LF modes make very little contribution and also increase the number of retained modes, which leads to loss of computational efficiency. Therefore, MF response analysis should consider low truncated modes to improve the computational efficiency. The current work is focused on improving the computational efficiency using a AS and a frequency sweep algorithm. Finite element simulation for a MEMS resonator array showed that the performance of the presented method is superior to a conventional method.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.2
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• pp.125-131
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• 2003

In this paper Power Flow Finite Element Method(PFFEM) has been implemented to analyze the vibration of a plate in mid and high frequency ranges. In order to solve the vibration energy governing equation in Power Flow Analysis(PFA), The Finite Element Method(FEM) was used as a numerical tool. It allowed one to predict the distribution of displacement and Intensity in the plate vibrating at mid and high frequencies. The results were compared with the analytical solutions and the approximate FEM solutions. The comparison showed that PFFEM can be an effective tool to analyze the structural vibration in mid and high frequency ranges.

• Fashion & Textile Research Journal
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• v.11 no.4
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• pp.602-613
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• 2009

This study aims to improve the fit of middle and high school girls' uniforms. This study researched on the sizing system reflecting their body figures. The results are as follows. First, to classify the middle and high school girls' figures, factor analysis, and cluster analysis were conducted. 4 factors were extracted for upper body of the middle school girls, and 5 factors were extracted for the highschool girls. For the lower body, 3 factors were extracted for both the middle and high school girls. The middle school girls were then divided into 4 groups for the upper body and 4 groups for the lower body. The high school girls were divided into 4 upper and lower body groups. Third, KS size intervals were used for frequency distribution of height and bust for the bodice, height and waist for the lower body. Sizing system of the uniform company and the frequency distribution of sizes were compared. As a result, sizing system of the uniform company and the frequency distribution overlapped very little. Fourth, sizing system considering body type distribution and high frequency distribution of sizes was suggested. As a result when 6 sizes were suggested 30% of the population was covered, and when 11 sizes were suggested 55% of the population was covered.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.6
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• pp.108-113
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• 1999

For cylindrical shells, the closed-form solutions are confined to the specific boundary and/or loading conditions. Though the finite element method is certainly a powerful solution approach for the structural dynamics problems, it has been well known to provide the solution reliable only in the low frequency region due to the inherent high sensitivities of structual and numerical modeling errors. Instead, the spectral element method has been proved to provide accurate dynamic characteristics of a structure even at the ultrasonic frequency region. Since the wave characteristic of a cylindrical shell becomes identical to that fo a flat plate as the frequency increases, an equivalent plate model (EPM) representing the high-frequency dynamic characteristics of the cylindrical shell is introduced herein. The EPM-based spectral element analysis solutions are compared with the known analytical solutions for the cylindrical shells to confirm the validity of the present modeling approach.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.782-785
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• 2006

The Power Flow Analysis(PFA) can be effectively used to predict structural vibration in medium-to-high frequency range. In this paper, Power Flow Finite Element Method (PFFEM) based on PFA has been used to predict the vibration of an automobile door. The predicted results for the frequency response function of the door have been compared with corresponding experimental results. In the experiment, the automobile door has been divided into several subsystems and the loss factor of each subsystem has been measured. The input mobility at a source point has been also measured. The data for the loss factors and the input mobility have been used as the input data to predict the vibration of the automobile door with PFFEM. The frequency response functions have been measured over the surface of the door. The comparison between the experimental results and the predicted results for the frequency response functions showed that PFFEM could be an effective tool to predict the structural vibration.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.121-125
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• 2013

It is an analysis about electromagnetic wave which is generated from a Spark plug cable of Distributorless spark ignition system. In case of Distributorless spark ignition system, high frequency generation is an ignition coil and Spark plug cable and Spark plug could be activated with electromagnetic wave radiation antenna. I calculated a resonant frequency with HFSS by measuring length of Spark plug cable and Spark plug. The antenna was considered as ${\lambda}/4$ monopole antenna in this calculation. According to power spectrum measurement analysis of engine room radiated electromagnetic wave and calculated Resonant frequency, it is possible to find out that the Distributorless spark ignition system radiates high frequency energy in certain frequency band.

• Journal of information and communication convergence engineering
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• v.19 no.1
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• pp.48-53
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• 2021

Herein, we propose a document analysis system that analyzes papers or reports transformed into XML(Extensible Markup Language) format. It reads the document specified by the user, extracts keywords from the document, and compares the frequency of keywords to extract the top-three keywords. It maintains the order of the paragraphs containing the keywords and removes duplicated paragraphs. The frequency of the top-three keywords in the extracted paragraphs is re-verified, and the paragraphs are partitioned into 10 sections. Subsequently, the importance of the relevant areas is calculated and compared. By notifying the user of areas with the highest frequency and areas with higher importance than the average frequency, the user can read only the main content without reading all the contents. In addition, the number of paragraphs extracted through the deep learning model and the number of paragraphs in a section of high importance are predicted.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.4_2
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• pp.475-480
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• 2021

The purpose of this study is to obtain the natural frequency of fuel supply pipes for vehicle engines through modal analysis and testing and compare the resulting values to ensure the reliability of the analysis. In other words, in this study, we obtain the unique frequency of the fuel pipe of the vehicle engine through analysis and testing and compare its results. Comparing the natural frequency obtained through analysis and testing, the first and third vibration modes obtained accurate natural frequency results of less than 1% and very similar results of less than 5% maximum error over the fourth vibration modes. These results are determined that if design changes of fuel pipes are made depending on the vehicle in the future, there will be no problem in obtaining the natural frequency of pipes that have been changed by analysis. Through future analysis and testing, durability and stability evaluation of connections of fuel supply pipes for vehicle engines will be carried out.