• Title/Summary/Keyword: energy degradation

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Photocatalytic Degradation of Chlorinated Hydrocarbons in Water (물에함유된 염소계 유기화합물의 광촉매 분해반응)

  • 김경남;김동형;이태규
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • 1995.05a
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    • pp.31-40
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    • 1995
  • The degradation of aqueous chlorinated compounds such as trichloroethylene (TCE), tetrachloroethylene (PCE) and dichloroacetic acid (DCA) to $CO_2$ and HCl was accomplished in the presence of UV light and suspended TiO$_2$ slurries. The decomposition of chlorinated hydrocarbons at 253.7 m irradiation was more effective than that at 360 nm irradiation. Our results show that 253.7 nm irradiation alone can be used for decomposing some chlorinated hydrocarbons such as PCE and TCE.

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State-of-Arts of Primary Concrete Degradation Behaviors due to High Temperature and Radiation in Spent Fuel Dry Storage (사용후핵연료 건식저장 콘크리트의 고열과 방사선으로 인한 주요 열화거동 분석)

  • Kim, Jin-Seop;Kook, Donghak;Choi, Jong-Won;Kim, Geon-Young
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.16 no.2
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    • pp.243-260
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    • 2018
  • A literature review on the effects of high temperature and radiation on radiation shielding concrete in Spent Fuel Dry Storage is presented in this study with a focus on concrete degradation. The general threshold is $95^{\circ}C$ for preventing long-term degradation from high temperature, and it is suggested that the temperature gradient should be less than $60^{\circ}C$ to avoid crack generation in concrete structures. The amount of damage depends on the characteristics of the concrete mixture, and increases with the temperature and exposure time. The tensile strength of concrete is more susceptible than the compressive strength to degradation due to high temperature. Nuclear heating from radiation can be neglected under an incident energy flux density of $10^{10}MeV{\cdot}cm^{-2}{\cdot}s^{-1}$. Neutron radiation of >$10^{19}n{\cdot}cm^{-2}$ or an integrated dose of gamma radiation exceeding $10^{10}$ rads can cause a reduction in the compressive and tensile strengths and the elastic moduli. When concrete is highly irradiated, changes in the mechanical properties are primarily caused by variation in water content resulting from high temperature, volume expansion, and crack generation. It is necessary to fully utilize previous research for effective technology development and licensing of a Korean dry storage system. This study can serve as important baseline data for developing domestic technology with regard to concrete casks of an SF (Spent Fuel) dry storage system.

Chaotic evaluation of material degradation time series signals of SA 508 Steel considering the hyperspace (초공간을 고려한 SA 508강의 재질열화 시계열 신호의 카오스성 평가)

  • 고준빈;윤인식;오상균;이영호
    • Journal of Welding and Joining
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    • v.16 no.6
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    • pp.86-96
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    • 1998
  • This study proposes the analysis method of time series ultrasonic signal using the chaotic feature extraction for degradation extent evaluation. Features extracted from time series data using the chaotic time series signal analyze quantitatively degradation extent. For this purpose, analysis objective in this study is fractal dimension, lyapunov exponent, strange attractor on hyperspace. The lyapunov exponent is a measure of the rate at which nearby trajectories in phase space diverge. Chaotic trajectories have at least one positive lyapunov exponent. The fractal dimension appears as a metric space such as the phase space trajectory of a dynamical system. In experiment, fractal correlation) dimensions, lyapunov exponents, energy variation showed values of 2.217∼2.411, 0.097∼ 0.146, 1.601∼1.476 voltage according to degardation extent. The proposed chaotic feature extraction in this study can enhances precision ate of degradation extent evaluation from degradation extent results of the degraded materials (SA508 CL.3)

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Degradation of Chlorinated Organic Compounds by Zero Valent Metals and an Electron carrier

  • Kim, Young-Hun
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2001.04a
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    • pp.53-56
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    • 2001
  • The degradation of tetrachloroethene (PCE) and trichloroethene (TCE) by vitamin B$_{12}$, an electron mediator was examined when zero valent metals (ZVMs) were used as built electron donors. Dechlorination of PCE and TCE by iron and zinc in the presence of vitamin B$_{12}$ showed that the zinc and vitamin B$_{12}$ combination greatly enhances the reaction rates for both PCE and TCE, but iron and vitamin B$_{12}$ result in an increase in reactivity only for PCE degradation, not for TCE degradation in comparing with meta]s only. This result indicates vitamin B$_{12}$(I) Is active towards both PCE and TCE degradation while vitamin B$_{12}$(II) is active towards both PCE. Calculated activation energies for the dechlorination of PCE in the presence of Vitamin B$_{12}$ showed that vitamin B$_{12}$ lowered the activation energy about 40-60 kJ/㏖ for the both metals.the both metals.

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A Kinetic Study of Thermal Degradations of Chitosan/Polycaprolactam Blends

  • Liao, Shen-Kun;Hung, Chi-Chih;Lim, Ming-Fung
    • Macromolecular Research
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    • v.12 no.5
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    • pp.466-473
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    • 2004
  • We have used FT-IR spectra to explain the effects of hydrogen bonding between chitosan and polycaprolactam (PA6). A dynamic mechanical analysis study suggested that the optimum chitosan and PA6 miscibility under the conditions of this experiment were obtained at a blending ratio of 40:60. We studied the thermal degradation of chitosan blended with PA6 (chitosan/PA6) by thermogravimetric analysis and kinetic analysis (by the Ozawa method). Dry chitosan and PA6 exhibited a single stage of thermal degradation and chitosan/PA6 blends having> 20 wt% PA6 exhibited at least two stages of degradation. In chitosan/PA6 blends, chitosan underwent the first stage of thermal degradation; the second stage proceeded at a temperature lower than that of PA6, because the decomposition product of chitosan accelerated the degradation of PA6. The activation energies of the blends were between 130 and 165 kJ/mol, which are also lower than that of PA6.

Analysis of degradation of distribution lightning arresters as degradation degree (열화정도에 따른 배전용 피뢰기의 열화특성 분석)

  • 장동욱;박동배;박영국;이용희;강성화;임기조
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.07a
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    • pp.140-143
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    • 2000
  • The primary function of ZnO lightning arrester is to protect transmission and distribution equipment from overvoltages and to absorb electrical energy resulting from lightning or switching surges and form temporary overvoltage. However, ZnO lightning arrester are known to exhibit an increases in resistive current with time, the rate of increase being exacerbated with increasing applied voltage and ambient temperature. So, it is important to the leakage current measurement of ZnO lightning arrester. In addition, since the resistive leakage current caused by deterioration of ZnO lightning arrester mainly caused an increase of the third harmonic component, thereby it is possible the arrester degradation diagnosis by measuring the third harmonic component in the total leakage current. The leakage current and third harmonic component are measured and used to investigate the degradation diagnosis of ZnO element of arrester. Also the SEM photography is used to investigate the change of crystal structure of ZnO element with degradation.

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Seismic behavior of energy dissipation shear wall with CFST column elements

  • Su, Hao;Zhu Lihua;Wang, Yaohong;Feng, Lei;Gao, Zeyu;Guo, Yuchen;Meng, Longfei;Yuan, Hanquan
    • Steel and Composite Structures
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    • v.43 no.1
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    • pp.55-66
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    • 2022
  • To develop high-efficiency lateral force resistance components for high-rise buildings, a novel energy dissipation shear wall with concrete-filled steel tubular (CFST) column elements was proposed. An energy dissipation shear wall specimen with CFST column elements (GZSW) and an ordinary reinforced concrete shear wall (SW) were constructed, and experimented by low-cycle reversed loading. The mechanical characteristics of these two specimens, including the bearing capacity, ductility, energy dissipation, and stiffness degradation process, were analyzed. The finite-element model of the GZSW was established by ABAQUS. Based on this finite-element model, the effect of the placement of steel-plate energy dissipation connectors on the seismic performance of the shear wall was analyzed, and optimization was performed. The experiment results prove that, the GZSW exhibited a superior seismic performance in terms of bearing capacity, ductility, energy dissipation, and stiffness degradation, in comparison with the SW. The results calculated by the ABAQUS finite-elements model of GZSW corresponded well with the results of experiment, and it proved the rationality of the established finite-elements model. In addition, the optimal placement of the steel-plate energy dissipation connectors was obtained by ABAQUS.

Seismic Response of Seismically-Isolated Nuclear Power Plants considering Age-related Degradation of High Damping Rubber Bearing (고감쇠고무 적층받침의 경년열화를 고려한 원전구조물의 지진응답)

  • Park, Junhee;Choun, Young-Sun;Choi, In-Kil
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.26 no.2
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    • pp.131-138
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    • 2013
  • The high damping rubber bearings contributed to reduce a seismic force transmitted to upper structures, the material properties of rubber changes with time and the rubber with age-related degradation can affect the seismic response of structures and equipments. Therefore the seismic response of structure considering age-related degradation of isolators should be evaluated. In this paper, the stiffness and damping for isolators were defined using the aging data proposed by other researchers. The reactor containment building and the auxiliary building were selected to conduct the nonlinear analysis and the natural frequency, maximum responses, floor response spectrum(FRS) were evaluated with time using the four earthquakes with different frequency contents. According to the analysis results, the seismic responses are increased by the age-related degradation of isolators and the detail inspections should be conducted up to 20 years because it was presented that the change of FRS was high during this period.

Thermal Degradation Analyses of Epoxy-Silica Nano Composites (에폭시-실리카 나노 복합소재의 열화 특성 및 거동 분석)

  • Jang, Seo-Hyun;Han, Yusu;Hwang, Do Soon;Jung, Joo Won;Kim, Yeong K.
    • Composites Research
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    • v.33 no.5
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    • pp.268-274
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    • 2020
  • This paper analyzed the degradation behaviors of silica nano epoxy composite based on the isoconversional method. The size of the silica nano particle was about 12 nm and the particles were mixed by three different weight ratios to make the degradation test samples. The thermogravimetric analyses were performed under six different temperature increase rates to measure the weight changes. Four different methods, Friedman, Flynn-Wall-Ozawa, Kissinger and DAEM (Distributed Activation Energy Method), were employed to calculate the activation energies depending on the conversion ratios, and their calculation results were compared. The results represented that the activation energy was increased when the silica nano particles were mixed up to 10%, indicating the definite contribution of the particles to the degradation behavior enhancements. However, the enhancement was not proportional to the particle mixture ratio by demonstrating the similar activation energies between 10% and 18% samples. The calculation results by the different methods were also compared and discussed.

Mitigation of Potential-Induced Degradation (PID) for PERC Solar Cells Using SiO2 Structure of ARC Layer (반사방지막(ARC)의 SiO2 구조에 따른 PERC 태양전지 PID 열화 완화 상관관계 연구)

  • Oh, Kyoung Suk;Park, Ji Won;Chan, Sung Il
    • Current Photovoltaic Research
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    • v.8 no.4
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    • pp.114-119
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    • 2020
  • In this study, Mitigation of Potential-induced degradation (PID) for PERC solar cells using SiO2 Structure of ARC layer. The conventional PID test was conducted with a cell-level test based on the IEC-62804 test standard, but a copper PID test device was manufactured to increase the PID detection rate. The accelerated aging test was conducted by maintaining 96 hours with a potential difference of 1000 V at a temperature of 60℃. As a result, the PERC solar cell of SiO2-Free ARC structure decreased 22.11% compared to the initial efficiency, and the PERC solar cell of the Upper-SiO2 ARC structure decreased 30.78% of the initial efficiency and the PID reliability was not good. However, the PERC solar cell with the lower-SiO2 ARC structure reduced only 2.44%, effectively mitigating the degradation of PID. Na+ ions in the cover glass generate PID on the surface of the PERC solar cell. In order to prevent PID, the structure of SiNx and SiO2 thin films of the ARC layer is important. SiO2 thin film must be deposited on bottom of ARC layer and the surface of the PERC solar cell N-type emitter to prevent surface recombination and stacking fault defects of the PERC solar cell and mitigated PID degradation.