• Title/Summary/Keyword: phase-field method

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The Study of the Process of Design on the Application of the Architectural Field Concept (건축장 개념을 적용한 설계과정 연구)

  • Lee, Seung-Yong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.8
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    • pp.3698-3703
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    • 2012
  • The architectural design process is consisted of the phase of programming and the phase of the design. The contemporary architectural scheme, as a datascape, a rhizome structure and a diagram, is based on the concept of modern physics. And it is applied on the phase of design by synthesizing data. Like this, the design of the architectural field is accomplished in the phase of design. For design of the architectural field, the characteristics of the architectural field is considered as the viewpoint of design in the procedure. First, according to the area which is defined by relations of environments, around architectures and so on, the net system of relations is designed as area. Second, design the linkage between building and space, building and building, space and space, according to the correspondence each other. Third, design the method or form of connecting building and space to one as a building and a space are no longer divided but are understood by one. As a result, for the design of architectural field, it is necessary to define the criteria by the characteristics of architectural field and the architectural field is designed by process.

Electrical Properties and Self-poling Mechanism of CNT/PVDF Piezoelectric Composite Films Prepared by Spray Coating Method

  • Lee, Sunwoo;Jung, Nak-Chun
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.08a
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    • pp.256-256
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    • 2013
  • Carbon nanotubes (CNT) / polyvinylidene fluoride (PVDF) piezoelectric composite films for nanogenerator devices were fabricated by spray coating method. When the CNT/PVDF mixture solution passes through the spray nozzle with small diameter by the compressed nitrogen gas, electric charges are generated in the liquid by a triboelectric effect. Then randomly distributed ${\beta}$ phase PVDF film could be re-oriented by the electric field resulting from the accumulated electrical charges, and might be resulted in extremely one-directionally aligned ${\beta}$ phase PVDF film without additional electric field for poling. X-ray diffraction patterns were used to investigate crystal structure of the CNT/PVDF composite films. It was confirmed that they revealed extremely large portion of the ${\beta}$ phase PVDF crystalline in the film. Therefore we could obtain the poled CNT/PVDF piezoelectric composite films by the spray coating method without additional poling process. Charge accumulation and resulting electric field generation mechanism by spray coating method were shown in Fig. 1. The capacitance of the CNT/PVDF films increased by adding CNTs into the PVDF matrix, and finally saturated. However, the I-V curves didn't show any saturation effect in the CNT concentration range of 0~4 wt%. Therefore we can control the performance of the devices fabricated from the CNT/PVDF composite film by adjusting the current level resulted from the CNT concentration with the uniform capacitance value.

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The Experimental Study and Comparison on Usage of Vibration Monitoring Sensors for Positioning of Balancing on Rotating Machinery (진동 감시용 위치 결정 센서의 위상오차에 대한 실험적 고찰과 비교평가)

  • Oh, Seung-Tae;Yoo, Mu-Sang;Bong, Suk-Keun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.10a
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    • pp.314-320
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    • 2014
  • Field balancing is required in any kind of phase information for the determination location balancing mass toward a rotor unbalance mass. Phase or phase angle is a measurement of the relationship of how one vibration signal which relates to another vibration signal and is commonly used to calculate the placement of balance weight. In this paper, A right guideline shows the photo optical speed sensor as the external keyphasor is a very useful when diagnosing machinery vibration problems on considering a phase lag comparing to the laser optical speed sensor. Some experimental results generate the interesting phase errors when appling to a wrong conditions. So, Usage of photo optical speed sensor which is used primarily to measure the shaft rotating speed serves as a reference for measuring vibration phase information has effect on the placement of phase angle how it was misunderstood. This paper will help a right method to search for the position of balancing weight and serves as baseline for further measurements using low cost and much easier user convenience. It is concluded that the propose baseline is likely to be applicable to apply to the practical field balancing weight.

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The Experimental Study and Comparison on Usage of Vibration Monitoring Sensors for Positioning of Balancing on Rotating Machinery (진동 감시용 위치 결정 센서의 위상오차에 대한 실험적 고찰과 비교 평가)

  • Oh, Seung-Tae;Yoo, Mu-Sang;Bong, Suk-Keun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.25 no.2
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    • pp.101-107
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    • 2015
  • Field balancing is required in any kind of phase information for the determination location balancing mass toward a rotor unbalance mass. Phase or phase angle is a measurement of the relationship of how one vibration signal which relates to another vibration signal and is commonly used to calculate the placement of balance weight. In this paper, A right guideline shows the photo optical speed sensor as the external KeyPhasor is a very useful when diagnosing machinery vibration problems on considering a phase lag comparing to the laser optical speed sensor. Some experimental results generate the interesting phase errors when appling to a wrong conditions. So, Usage of photo optical speed sensor which is used primarily to measure the shaft rotating speed serves as a reference for measuring vibration phase information has effect on the placement of phase angle how it was misunderstood. This paper will help a right method to search for the position of balancing weight and serves as baseline for further measurements using low cost and much easier user convenience. It is concluded that the propose baseline is likely to be applicable to apply to the practical field balancing weight.

A Study on the Characteristics in Single-Phase Line-Start Permanent Magnet Moter (단상 유도형 동기 전동기(LSPM)의 특성해석에 관한 연구)

  • Jung, Dae-Sung;Kim, Seung-Ju;Lee, Jin-Hun;Choi, Jae-Hak;Lee, Ju
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.3
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    • pp.125-131
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    • 2007
  • Electric motor efficient improvement from home appliance field is important to the effect reducing the energy consumption. But the electric motor design/analysis technology is still insufficient. Specially the electric motor design/analysis technology of satisfying characteristic of both the induction motor and the synchronous motor such as Line start permanent motor. Therefore the electric motor design/analysis technology is urgently demanded reliability. This paper proposes the sing1e-phase line-start permanent magnet motor to develop the motor it with be able to alternate the sing-phase induction motor it is a refrigerator compressor motor. The sing-phase induction motor is analyzed in the steady state. And we have a certification test to compare our single-phase line-start permanent magnet motor with the sing-phase induction motor. In order to improve the performance, the stator of the single-phase line-start permanent magnet motor is same as the stator of the sing-phase induction motor and changes the rotor form and has the permanent magnet. It used the Finite Element Method(FEM) which is widely used with electronic-magnetic field numerical analysis method.

Partial Discharge Pattern Recognition using Neural Network (뉴우럴 네트워크에 의한 부분방전 패턴 인식)

  • Lee, June-Ho;Hozumi, Naohiro;Okamoto, Tatsuki
    • Proceedings of the KIEE Conference
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    • 1995.07c
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    • pp.1304-1306
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    • 1995
  • In this study, a neural network algorithm through a data standardization method was developed to discriminate the phase-shifted partial discharge(PD) patterns such as a $\phi$-q-n pattern. Considering the PD measurement in the field, it is not so easy to acquire absolute phase angles of PD pulses. As a consequence, one of the significant problems to be solved in applying the neural network algorithm to practical systems is to develop a method that can discriminate phase-shifted $\phi$-q-n patterns. Therefore, authors established a new method which could convert phase-shifted $\phi$-q-n patterns to a standardized $\phi$-q-n pattern which was not influenced by phase shifting. This new standardization method improved the recognition performance of a neural network for the phase-shifted $\phi$-q-n patterns considerably.

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Development of advanced phase spectrum for surface wave method (표면파 시험을 위한 향상된 위상각 스펙트럼 결정방법의 개발)

  • Park, Hyung-Choon;Joh, Seung-Eun
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.03a
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    • pp.599-604
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    • 2008
  • The dispersive phase velocity of a wave propagating through a system is an important parameter and carries valuable information in non-destructive tests related to multilayered systems such as a soil site. The dispersive phase velocity of a wave can be determined using the phase spectrum, which is easily evaluated through the cross power spectrum. However, the phase spectrum as determined using the cross power spectrum is sensitive to background noise which always exists in the field. This causes difficulties in the determination of the dispersive phase velocities. In this paper, a new method to evaluate the phase spectrum using the harmonic wavelet transform is proposed. The proposed method can successfully remove background noise effects. To evaluate the validity of the proposed method, numerical simulations of multi-layered systems were performed. Phase spectrums by the proposed method were found to be in good agreement with the actual phase spectrums under conditions characterized by heavy background noise. This shows the potential of the proposed method.

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Beam Analysis of Underwater Conformal Array by Using Cylindrical Acoustic Holography (원통면 음향 홀로그래피를 이용한 수중음향 곡면배열센서의 빔 해석)

  • Kwon, Hyu-Sang;Park, Seong-Chol;Seo, Hee-Seon;Shin, Gu-Kyun;Joh, Ghee-Young
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.10
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    • pp.987-995
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    • 2009
  • As an experimental technique to analyze the far-field characteristics of underwater cylindrical array sensors, cylindrical acoustic holography is studied. Inside an laboratory water tank, far-field directivity patterns as well as near-field source images are reconstructed from the measured hologram by hydrophone array. Approximate equation for far-field directivity estimation is derived based on stationary phase method. The simulation and experiment show well usefulness of the proposed method in application of underwater array sensors.

Beam analysis of underwater conformal array by using cylindrical acoustic holography (원통면 음향 홀로그래피를 이용한 수중음향 곡면배열센서의 빔 해석)

  • Kwon, Hyu-Sang;Park, Seong-Chol;Seo, Hee-Seon;Shin, Gu-Kyun;Joh, Ghee-Young
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2009.04a
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    • pp.111-116
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    • 2009
  • As an experimental technique to analyze the far-field characteristics of underwater cylindrical array sensors, cylindrical acoustic holography is studied. Inside an laboratory water tank, far-field directivity patterns as well as near-field source images are reconstructed from the measured hologram by hydrophone array. Approximate equation for far-field directivity estimation is derived based on stationary phase method. The simulation and experiment show well usefulness of the proposed method in application of underwater array sensors.

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A Study on the Electrical Characteristics of Renewable Electrical Energy Superconducting Precursor using Organic Metal Salts Method for Electrical Power Transmission

  • Lee, Sang-Heon
    • Transactions on Electrical and Electronic Materials
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    • v.6 no.6
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    • pp.289-293
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    • 2005
  • We have fabricated superconductor ceramics by chemical process. A high Tc superconductor with a nominal composition of $Bi_2Sr_2Ca_2Cu_3O_y$ was prepared by the organic metal salts method. Experimental results suggest that the intermediate phase formed before the formation of the superconductor phase may be the most important factor. The relation between electromagnetic properties of Bi HTS and external applied magnetic field was studied. The electrical resistance of the superconductor was increased by the application of the external magnetic field. But the increase in the electrical resistance continues even after the removal of the magnetic field. The reason is as follows; the magnetic flux due to the external magnetic field penetrates through the superconductor and the penetrated magnetic flux is trapped after the removal of the magnetic flux.