• Title, Summary, Keyword: Degradation

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Study on the Degradation Behavior of Berberine Dye and Berberine Dyed Silk using Hydrogen Peroxide/UV/Oxygen Treatment (과산화수소/자외선/산소 처리를 이용한 베르베린 염료 및 염직물의 퇴화거동 연구)

  • Ahn, Cheun-Soon
    • The Research Journal of the Costume Culture
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    • v.20 no.2
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    • pp.238-250
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    • 2012
  • This study examined the degradation behavior of SB(standard berberine) dye and SB dyed silk using HPLC-MS instrument after degradation in the hydrogen peroxide/ultraviolet ray radiation/oxygen system up to 9 days and 40 hours respectively. In the degraded samples, berberine was detected at 5.2 min in the SB dye and 5.3 min in the SB dyed silk with its molecular ion=336 and the UV spectra of quaternary alkaloid. Degradation product 3(m/z=102) newly appeared after 5 day degradation treatment with continued increase till the end of degradation treatment. The amount of berberine in the degraded dye decreased with degradation progression. In the silk dyeings, berberine was detected only up to 21 hour degradation sample. The amount of berberine decreased dramatically during the first 6 hours of degradation treatment. The CIELAB color measurement of the silk dyeings showed dramatic change in the b* value, near zero in the 40 hour degraded silk. CIELAB and Munsell color measurements were in agreement with the HPLC-MS results of the dyed silk in the change of berberine content that the degraded silk became white and lost yellow color.

Study on stiffness deterioration in steel-concrete composite beams under fatigue loading

  • Wang, Bing;Huang, Qiao;Liu, Xiaoling;Ding, Yong
    • Steel and Composite Structures
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    • v.34 no.4
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    • pp.499-509
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    • 2020
  • The purpose of this paper is to investigate the degradation law of stiffness of steel-concrete composite beams after certain fatigue loads. First, six test beams with stud connectors were designed and fabricated for static and fatigue tests. The resultant failure modes under different fatigue loading cycles were compared. And an analysis was performed for the variations in the load-deflection curves, residual deflections and relative slips of the composite beams during fatigue loading. Then, the correlations among the stiffness degradation of each test beam, the residual deflection and relative slip growth during the fatigue test were investigated, in order to clarify the primary reasons for the stiffness degradation of the composite beams. Finally, based on the stiffness degradation function under fatigue loading, a calculation model for the residual stiffness of composite beams in response to fatigue loading cycles was established by parameter fitting. The results show that the stiffness of composite beams undergoes irreversible degradation under fatigue loading. And stiffness degradation is associated with the macrobehavior of material fatigue damage and shear connection degradation. In addition, the stiffness degradation of the composite beams exhibit S-shaped monotonic decreasing trends with fatigue cycles. The general agreement between the calculation model and experiment shows good applicability of the proposed model for specific beam size and fatigue load parameters. Moreover, the research results provide a method for establishing a stiffness degradation model for composite beams after fatigue loading.

A Study of the Roust Degradation Model by Analyzing the Filament Lamp Degradation Data (헤드램프용 필라멘트 램프 가속열화데이터 분석을 통한 로버스트 열화모형 연구)

  • Sung, Ki-Woo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.20 no.6
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    • pp.132-139
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    • 2012
  • It is generally needed to test durability and lifetime when we develop parts in new technology. In this paper, the accelerated degradation analysis methods are developed to test them. This study is presented robust model estimation method that is less affected by outlier in regresstion model estimation. In addition, the lifetime can be predicted by Degradation-stress relationship in stress level.

Studies on Polyacrylonitrile (2) Thermal Degradation of Polyacrylonitrile (폴리아크릴로니트릴에 關한 硏究 (第 2 報) 폴리아크릴로니트릴의 熱分解에 關하여)

  • ICK SAM NOH
    • Journal of the Korean Chemical Society
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    • v.11 no.2
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    • pp.70-76
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    • 1967
  • Structural changes attending polyacrylonitrile(PAN) upon heating and treating with nucleophilic reagents have been studied for some time and a few authors have studied on the thermal degradation, particularly on the characterization of degradation products in PAN. It is the purpose of this paper to report the kinetic study on the thermal degradation above $250^{\circ}C$ and make some suggestions as to the degradation process and mechanism in PAN. The degradation process in PAN is considered that three reactions are combined in two steps. Random chain scission accompanying the naphthylidine-type ring formation is the first step and the degradation of naphthylidine-type ring occurred as the next step. The reactions in the first step are competitive so that the maximum weight loss on pyrolysis of PAN, under such a condition that the degradation of naphthylidine-type ring is negligible, is depended on the relative reaction rate of these two competitive reactions.

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Planning of Accelerated Degradation Tests: In the Case Where the Performance Degradation Characteristic Follows the Lognormal Distribution (성능특성치의 열화가 대수정규분포를 따를 때의 가속열화시험 모형 개발)

  • Lim, Heonsang;Sung, Si-Il
    • Journal of Applied Reliability
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    • v.18 no.1
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    • pp.80-86
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    • 2018
  • Purpose: This article provides a mathematical model for the accelerated degradation test when the performance degradation characteristic follows the lognormal distribution. Method: For developing test plans, the total number of test units and the test time are determined based on the minimization of the asymptotic variance of the q-th quantile of the lifetime distribution at the use condition. Results: The mathematical model for the accelerated degradation test is provided. Conclusion: Accelerated degradation test method is widely used to evaluate the product lifetime within a resonable amount of cost and time. In this article. a mathematical model for the accelerated degradation test method is newly developed for this purposes.

A Study on the Degradation Characteristics of EPN (EPN의 분해특성에 관한 연구)

  • 이용두;김현희;김창영
    • Journal of Environmental Science International
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    • v.11 no.10
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    • pp.1103-1108
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    • 2002
  • In order to evaluate the degradation organophosphorus pesticide, EPN, in water environment, the effects of water temp.(10$^{circ}C,\;30^{\circ}C$), pH(3-11) and sunlight on its degradation were investigated during 10 days. The degradation rate of EPN(200 rpm) was faster at higher water temp. and higher pH, i.e., its degradation rate at pH 3, 5, 7, 9, 11 was 57, 63, 66, 69, 75%(1$0^{\circ}C$), and 70, 74, 79, 91, 97%(3$0^{\circ}C$) after 10 days, respectively. The effect of water temp. on its degradation was little in acidic condition, but was rather great in alkaline condition, with time. EPN was degraded fast at the alkaline condition by photolysis. At the condition of pH 11, EPN was degraded fast at the early stage in the first 2 days, but after that the degradation rate was weakened.

Strength Evaluation and Life Prediction of the Multistage Degraded Materials (다단계 모의 열화재의 재료강도 평가와 수명예측)

  • 권재도;진영준;장순식
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.9
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    • pp.2271-2279
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    • 1993
  • In the case of life prediction on the structures and machines after long service, it is natural to consider a degradation problems. Most of degradation data form practical structures are isolated data obtained at the time of periodical inspection or repair. From such data, it may be difficult to obtain the degradation curve available and necessary for life prediction. In this paper, for the purpose of obtaining a degradation curves, developed the simulate degradation method and fatigue test and Charpy impact test were conducted on the degraded, simulate degraded and recovered materials. Fatigue life prediction were conducted by using the relationship between fracture transition temperature (DBTT : vTrs) obtained from the Charpy impact test through the degradation process and fatigue crack growth constants of m and C obtained from the fatigue test.

Degradation of 2-chlorophenol by Ferrate(VI) (Ferrate(VI)를 이용한 2-chlorophenol의 분해특성 연구)

  • Choi, Hye-Min;Kwon, Jae-Hyun;Kim, Il-Kyu
    • Journal of Korean Society of Water and Wastewater
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    • v.25 no.1
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    • pp.63-74
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    • 2011
  • The degradation characteristics of 2-chlorophenol(2-CP) by Ferrate(VI) were studied. The degradation efficiency of 2-CP in aqueous solution was investigated at various values of pH, Fe(VI) dosage, initial concentration and aqueous solution temperature. The maximum degradation efficiencies of 2-CP were obtained at pH 7.0 and aqueous solution temperature of 25$^{\circ}C$. The degradation efficiency was proportional to dosage of Fe(VI). Also, the initial rate constant of 2-CP degradation increased with decreasing of the 2-CP initial concentration. In addition, the degradation pathway study for 2-CP was conducted with GC-MS analysis. Acetic acid, formic acid, benzaldehyde and benzoic acid were identified as reaction intermediates of the 2-CP degradation by Ferrate(VI).

Development of Degradation Agent for Oil Contaminated Soil using Modified Peat Moss and Organic Sludge (개량된 이탄과 유기성 슬러지를 이용한 유류오염토양 분해제 개발)

  • Kim, Soo-Hong;Lee, Chang-Han;Suh, Jung-Ho
    • KSBB Journal
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    • v.25 no.1
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    • pp.103-107
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    • 2010
  • Oil degradation agent was developed with organic sludge and modified peat moss (MPM) to recover oil contaminated soil. Waste sludge discharged from wastewater treatment plant of chemical plant in Ulsan National Industrial Park was used as organic sludge, and MPM was purchased. Organic sludge was adequate to use as growth medium for microorganism, the surface of MPM had porous structure which could enhance the cultivation condition of oil degradation microorganisms. Water contents and TPH variation with time were observed to investigate the degradation capacity of developed degradation agent. Water contents were rapidly decreased with higher contents of MPM, however, in case of TPH, high MPM content decreased the degradation capacity. Therefore, it was recommended that the content of MPM was controlled to below 10% in degradation agent as mixing organic sludge with MPM.

Oxidative Degradation Kinetics of Tocopherols during Heating

  • Chung, Hae-Young
    • Preventive Nutrition and Food Science
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    • v.12 no.2
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    • pp.115-118
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    • 2007
  • Tocopherols are important lipid-phase antioxidants that are subject to heat degradation. Therefore, kinetic analyses for oxidative degradation of tocopherols as a function of temperatures and times were performed. Alpha-, gamma- and delta-tocopherols dissolved in glycerol were heated at 100${\sim}$250$^{\circ}C$ for 5~60 min. Oxidized tocopherols were analyzed by HPLC using a reversed phase ${\mu}$-Bondapak C$_{18}$-column with two kinds of elution solvent systems in a gradient mode. The degradation kinetics for tocopherols followed a first-order kinetic model. The rate of tocopherol degradation was dependent on heating temperatures. The degradation rate constants for ${\gamma}$- and ${\delta}$-tocopherols were higher than those for ${\alpha}$-tocopherol. The experimental activation energies of ${\alpha}$-, ${\gamma}$- and ${\delta}$- tocopherols were 2.51, 6.05 and 5.34 kcal/mole, respectively. The experimental activation energies for the oxidative degradation of ${\gamma}$- and ${\delta}$-tocopherols were higher than that of ${\alpha}$-tocopherol.