• Title/Summary/Keyword: Dissipation factor

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Study on the Variation of Energy Dissipation Factor of Reinforced Concrete Beam under Cyclic Loading (반복하중을 받는 철근콘크리트 보의 에너지소산계수 변화 특성 고찰)

  • Suk-Hyeong Yoo;Dae-Young Kang
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.27 no.6
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    • pp.86-93
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    • 2023
  • As the hysteretic behavior of reinforced concrete members under cyclic loading progresses, the energy dissipation ability decreases due to a decrease in stiffness and strength and pinching effects. However, the guideline "Nonlinear Analysis Model for Performance-Based Seismic Design of Reinforced Concrete Building Structures, 2021" requires calculating a single energy dissipation factor for each member and all histeric step, so the decrease in energy dissipation capacity according to histeric step cannot be considered. It is judged that Therefore, in this study, the energy dissipation factor according to the histeric step was examined by comparing the existing experimental results and the nonlinear time history analysis results for a general beam under cyclic loading. The energy dissipation factor was calculated as the ratio of the energy dissipation amount of the actual specimen to the energy dissipation amount of the idealized elastoplastic behavior obtained as a result of nonlinear time history analysis. In the existing experiment results, the energy dissipation factor was derived by calculating one cycle for each histeric step, and the energy dissipation factor was derived based on the nonlinear modeling process in the guidelines. In the existing experimental study, the energy dissipation factor was calculated by setting each histeric step (Y-L-R), and the energy dissipation factor was found to be 0.36 in the Y-L step and 0.28 in the L-R step, and the energy dissipation factor in the guideline was found to be 0.31. This shows that the energy dissipation factor calculation formula in the guidelines does not indicate a decrease in the energy dissipation capacity of reinforced concrete members.

Development and Its Characteristics of a Dissipation Factor Standard (손실계수 표준기 제작 및 그 특성)

  • Kim, Han-Jun;Kang, Jeon-Hong;Han, Sang-Ok
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.06a
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    • pp.527-528
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    • 2006
  • A dissipation factor standard of decade type having the range of 1 to 0.0001 at the frequency of 1 kHz and 10 kHz was fabricated using "T" networks combined R and C components. The values of the fabricated dissipation factor standard were adjusted within 1% of the nominal values at 0.0001 dial range and 0.05% at the others. This dissipation factor standard is used as a working standard for calibration of a impedance measurement meter at KRISS and as a primary standard of dissipation factor field at NML-SIRIM in Malaysia.

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Study on Diagnosis for Transformers by Tan $\delta$ and Moisture of Insulation Oil According to Thermal Aging (절연유의 열열화에 따른 Tan $\delta$와 수분의 변화에 의한 변압기의 예방진단 연구)

  • HwangBo, Seung;Han, Min-Koo;Kwak, Hee-Ro;Kim, Jae-Chul
    • Proceedings of the KIEE Conference
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    • 1988.11a
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    • pp.241-245
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    • 1988
  • This paper reports the experiments regarding to diagnosis techniques for power transformers by measuring dissipation factor and moisture contents of mineral oils. Thermal aging environments of mineral oils were varied by the specially designed systems. Thermal aging of elevated temperature of $90^{\circ}C$ was performed for about 240 and 460 hours, respectively. Dissipation factor, permittivity, and water content were measured. Our test samples were not exposed to air. Dissipation factor increased while permittivity did not change. The level of dissipation factor determining the insulating quality of mineral oil was compared with the previous results of resistivity and several correction factor.

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Example study of the dissipation factor change according to the oil filtering in large oil-filled transformer (유입변압기 오일필터링에 따른 유전정접 변화사례 고찰)

  • Kong, Tae-Sik;Kim, Hee-Dong
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.2035_2036
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    • 2009
  • This paper is purpose to understand the dissipation factor properties of the oil-filled large transformer according to the oil filtering. In order to know the insulation characteristic change by insulating oil filtering, we carried out the insulation diagnostic test for the same transformer before oil filtering and after. The insulation diagnosis tests are consist of the megger, the polarization index, the AC current test, the dissipation factor test and the partial discharge test, Especially we took notice of dissipation factor change, we analyzed and made a comparison of the two cases test result.

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Measurement of the Degree of Cure of Thermosetting Resin Matrix Composite Materials (열경화성수지 복합재료의 경화정도의 측정에 관한 연구)

  • 김진수;이대길
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.9
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    • pp.2154-2164
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    • 1995
  • In this study, a dielectric cure monitoring system which consists of an electric circuit, a sensor and a personal computer was developed to on-line monitor the dielectric properties of carbon fiber epoxy composite materials. Also, the kinetic model of carbon fiber epoxy composite materials was developed by curve fitting of differential scanning calorimetry data. The start and end points of cure and the relationship between the dissipation factor and the degree of cure were obtained by comparing the dissipation factor from the dielectric properties with the degree of cure from the DSC data. The relationship between the dissipation factor and the degree of cure was tested under various temperature profiles.

Correlation of Piezocone Dissipation Results and Compression Index (피에조콘 소산결과와 압축지수의 상관관계)

  • Park, Young-Hwan;Kang, Beong-Joon;Lee, Jun-Hwan
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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    • pp.1204-1211
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    • 2008
  • Compression index is one of the important characteristic numbers in soft soil engineering. Since 1940's, many researchers have suggested various practical solutions to define the compression index of clay using other soil properties. But, these results are only can give us an outline of soft soil behavior. In this study, the relationships between pore water pressure dissipation test results and compression index were suggested using comparison results of both tests. This relationships are based on basic concept of consolidation phenomena, essential difference between pore water pressure dissipation test and consolidation test, and disagreements between theoretical time factor and real time factor. To identify proportional factor of proposed equation, Geotechnical investigation results of Kwang-Yang(KY) site and Busan New Port(BN) site were used. The proportional factor was 0.0031 from 20 to 50% of consolidation rate where correlation parameter($R^2$) is 0.9051.

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A study on the heat cycle aging of insulation materials in large generator stator windings (대형발전기 고정자권선 절연재료의 열 사이클에 의한 열화에 관한 연구)

  • 김희곤;박영관
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.45 no.4
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    • pp.553-557
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    • 1996
  • Heat cycle aging of insulating materials in large generator stator winding has been investigated using both on-line and off-line test methods. On this study, principally, off-line test against actual generator in service was carried out to acquire information about polarization index(PI) and dissipation factor, dissipation factor tip-up, maximum partial discharge for the purpose of remnant breakdown voltage and life assessment. It was found from the tests that both dissipation factor and maximum partial discharge decreased with the increase of operating hours and starting numbers. It was found from off-line tests that the remnant breakdown voltage had a strong relationship with both dissipation factor and maximum partial discharge the remnant breakdown voltage as a results of both operating hours and starting number and the nondestructive tests were proposed as parameters which can predict the remnant lifetime of insulating materials in large generator stator windings. (author). 8 refs., 8 figs., 2 tabs.

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Cure Monitoring of Composite Materials Using Dielectrometry (유전기법을 이용한 복합재료의 경화 모니터링)

  • 권재욱;김진국;김학성;이대길;최진경
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2000.11a
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    • pp.42-45
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    • 2000
  • The properties of thermosetting resins are dependent on the degree of cure and consolidation quality. Since the consolidation process of thermosetting resin matrix fiber composites is much dependent on the viscosity of resin in the composites, in this study, the dissipation factor which is a function of viscosity was measured by the newly developed Lacomtech dielectrometry apparatus and sensors. Using the measured dissipation factors, the relationship between the dissipation factor and degree of cure with respect to environmental temperature was investigated.

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On-line Cure Monitoring of Adhesive Joints by Dielectrometry (유전기법을 이용한 접착 조인트의 실시간 경화 모니터링)

  • 권재욱;진우석;이대길
    • Composites Research
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    • v.16 no.4
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    • pp.51-58
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    • 2003
  • Since the reliability of adhesively bonded joints is much dependent on the curing status of thermosetting adhesive, the on-line cure monitoring during the cure of adhesively joints could improve the quality of adhesively bonded joints. In this work, the dielectric method which measures the dissipation factor of the adhesive during the cure of joints and converts it into the degree of cure of the adhesive was devised. The relation between the dissipation factor and the degree of cure of adhesive was investigated, which could eliminate the temperature effect on the dissipation factor that is a strong function of the degree of cure and temperature of adhesive. From the investigation, it was found that the dissipation factor showed a trend similar to the cure rate of the adhesive.

Stress-related energy dissipation and damping model of concrete considering moisture content

  • Liu, Baodong;Zhang, Pengyuan;Lyu, Wenjuan
    • Advances in concrete construction
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    • v.13 no.6
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    • pp.423-431
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    • 2022
  • Although the influence of moisture content on the mechanical properties of concrete has been studied for a long time, research related to its influence on the damping and energy dissipation property of concrete structure is still very limited. In this paper, the relationship between damping property and moisture content of concrete using cyclic uniaxial compression is firstly presented, and the mechanism of the influence of moisture content on concrete damping and energy dissipation capacity is analyzed. Based on the experimental research, moisture-related damping and energy dissipation model is proposed. Results show that the dissipated energy of concrete and loss factor increase as the moisture content increasing. The energy dissipation coefficient reflecting the influence of stress level of concrete under cyclic load, decreases first and then increases as the moisture content increasing. The mechanism of moisture-related energy dissipation behavior can be divided into the reactive force of water, the development of the internal micro cracks and the pore water pressure. Finally, the proposed moisture-related damping and energy dissipation model are verified.