• Title/Summary/Keyword: degree of degradation

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Cellulose Biodegradation Modeling Using Endoglucanase and β-Glucosidase Enzymes (Endoglucanase와 β-Glucosidase 효소에 의한 셀룰로오스 생분해 모델링)

  • Cho, Sun-joo;Kim, Tae-wook;Cho, Daechul
    • Journal of Environmental Science International
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    • v.31 no.3
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    • pp.227-235
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    • 2022
  • In this study, a biodegradation model of based on molecular cellulose was established. It is a mathematical, kinetic model, assuming that two major enzymes randomly break glycosidic bonds of cellulose molecules, and calculates the number of molecules by applying the corresponding probability and degradation reaction coefficients. Model calculations considered enzyme dose, cellulose chain length, and reaction rate constant ratio. Degradation increased almost by two folds with increase of temperature (5℃→25℃). The change of degradation was not significant over the higher temperatures. As temperature increased, the degradation rate of the molecules increased along with higher production of shorter chain molecules. As the reaction rates of the two enzymes were comparative the degree of degradation for any combinations of enzyme application was not affected much. Enzyme dose was also tested through experiment. While enzyme dose ranged from 1 mg/L to 10 mg/L, the gap between real data and model calculations was trivial. However, at higher dose of those enzymes (>15 mg/L), the experimental result showed the lower concentrations of reductive sugar than the corresponding model calculation did. We determined that the optimal enzyme dose for maximum generation of reductive sugar was 10 mg/L.

Degradation Diagnosis by Void Defects Using a Neural Network (신경망을 이용한 보이드 결함에 의한 열화진단)

  • 최재관;김성홍;김재환
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.10
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    • pp.940-945
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    • 1998
  • In this paper, we obtained the data, which is required in training the neural network and diagnosing the degradation degree, by introducing the AE detection that is effective method in ordinary degradation diagnosis on activation. Aa the results of generalization tests by appling neural network to the unknown AE patterns obtained from two kinds of specimen, firstly as to evaluate an objective performance of neural network, the recognition ration for no-void specimen and 1[mm] -void specimen are appeared to be 98.9% and 92.5%, respectively. Also, in the evaluation of the adaptability of neural network with a new type of 0.2[mm] -void specimen, it is confirmed that the result appears to be 64% of recognition ratio at 94% of confidence interval coefficient in expectation output 0.2. On the other hand, the recognition capability of the neural network was confirmed by data from no-void and 1[mm] void specimen. The results prove the promising possibility of the application of ANN to discriminate specific void affecting as main degradation source at partial discharge condition in insulator containing multi-void by accummulated data base.

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A study on the Evaluation of Material Degradation of 1Cr-1Mo-0.25V Steel using Ball Indentation Method (압입법을 이용한 1Cr-1Mo-0.25V강의 열화도 평가에 관한 연구)

  • Seok, Chang-Sung;Kim, Jeong-Pyo;Ahn, Ha-Neul
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.4
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    • pp.151-159
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    • 2001
  • As huge energy transfer systems like a nuclear power plant, steam power plant and petrochemical plant are operated for a long time, mechanical properties are changed by degradation. The life time of the systems can be affected by the mechanical properties. BI(Ball Indentation) test has a potential to replace conventional fracture tests like a uniaxial tensile test, fracture toughness test, hardness test and so on. In this paper, we would like to present the ageing evaluation technique by the BI method. The four classes of the thermally aged 1Cr-!mo-0.25V specimens were prepared using an artificially accelerated aging method. Tensile tests, fracture toughness tests, hardness tests and BI tests were performed. The results of the BI tests were in good agreement with fracture characteristics by a standard fracture test method within 5%. The IDE(Indentation Deformation Energy) of a BI technique as a new parameter for evaluating a degradation was suggested and the new IDE parameter clearly depicts the degradation degree.

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A Study on the Evaluation of Material Degradation using Ball Indentation Method (압입법을 이용한 재료 열화의 평가에 관한 연구)

  • Kim, Jeong-Pyo;Seok, Chang-Sung;Ahn, Ha-Neul
    • Proceedings of the KSME Conference
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    • 2000.11a
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    • pp.171-176
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    • 2000
  • As huge energy transfer systems like a nuclear power plant, steam power plant and petrochemical plant are operated for a long time, mechanical properties are changed by degradation. The life time of the systems can be affected by the mechanical properties. BI(Ball Indentation) test has a potential to replace conventional fracture tests like a uniaxial tensile test, fracture toughness test, hardness test and so on. In this paper, we would like to present the aging evaluation technique by the BI method. The four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared using an artificially accelerated aging method. Tensile tests, fracture toughness tests, hardness tests and BI tests were performed. The results of the BI tests were in good agreement with fracture characteristics by a standard fracture test method. The IDE(Indentation Deformation Energy) of a BI technique as a new parameter for evaluating a degradation was suggested and the new IDE parameter clearly depicts the degradation degree.

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Methods for Reducing Rolling effect in Optical Pickup Actuator (광픽업 액츄에이터의 롤링 저감 대책)

  • 정덕영;송병륜;이영빈;신경식;성평용;이주형
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.368-372
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    • 2002
  • Since rolling (Radial AC Tilt) motion in Optical Pickup Actuator causes RF signal degradation, many researches have been done to find out how to reduce rolling degree. This paper aims to introduce two methods of reducing rolling degree with their theoretical concepts and experimental results. First method rearranges magnetic circuit and the other one adjusts the proportion of the distances among mass center, actuating center and supporting center.

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A Study on Performance Degradation Analysis of Gas Turbine Combined Heat and Power Plant (가스터빈 열병합발전소 성능저하 분석에 관한 연구)

  • Kim, Hong Joo;Kim, Byeong Heon;Oh, Byeong Soo
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.28 no.6
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    • pp.248-255
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    • 2016
  • In this study, the degree of performance changes between the guaranteed performance and the performance after a certain operating start time is calculated by using the performance test of gas turbine CHP. The reason of the performance degradation will then be analysed. For some results of the CHP plant performance tests the comprehensive electric power output was 8,380 kW lower than the guaranteed performance, and the gas turbine's output was reduced to about 250 kW whenever ambient temperatures rose to $1^{\circ}C$. Also, causes of the performance degradation of gas turbines are ambient temperature rise, temperature aging and air compressor's efficiency drop.

Mechanical Degradation of Polymers in Dilute Solutions. The Influence of the Temperature on the Scission (稀薄溶液에서의 polymer의 機械的切斷. 切斷에 미치는 온도의 영향)

  • Won, Yeong-Moo;Takashi Fukutomi;Toshio Kakurai;Tatsuya Noguchi
    • Journal of the Korean Chemical Society
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    • v.15 no.3
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    • pp.109-116
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    • 1971
  • The mechanical degradation of poly (${\alpha}$-methyl styrene) in several mixed solvents (toluene-n-butyl alcohol, toluene-sec-butyl alcohol, toluene-kerosene, toluene-methyl ethyl ketone), from $1^{\circ}C to $45^{\circ}C$, was studied using the capillary flow method. The velocity constant of scission reaction (k) and the limited degree of polymerization (g) were compared at the same value of [${\eta}$] at each temperatures. As results, mechanical degradation of polymer in dilute mixed solutions is affected by composition of solvents around the polymer chains.

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Lifetime Assessment for Oil-Paper Insulation using Thermal and Electrical Multiple Degradation

  • Kim, Jeongtae;Kim, Woobin;Park, Hung-Sok;Kang, Ji-Won
    • Journal of Electrical Engineering and Technology
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    • v.12 no.2
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    • pp.840-845
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    • 2017
  • In this paper, in order to investigate the lifetime of oil-paper insulation, specimens were artificially aged with thermal and electrical multiple stresses. Accelerated ageing factors and equivalent operating years for each aging temperatures were derived from results of tensile strengths for the aged paper specimens. Also, the evaluation for the multi-stress aged specimens were carried out through the measurement of impulse breakdown voltage at high temperature of $85^{\circ}C$. The lifetimes of the oil-paper insulations were calculated with the value of 66.7 for 1.0 mm thickness specimens and 69.7 for 1.25 mm thickness specimens throughout the analysis of impulse BD voltages using equivalent operating years, which means that dielectric strengths would not be severely decreased until the mechanical lifetime limit. Therefore, for the lifetime evaluation of the oil-paper insulation, thermal aging would be considered as a dominant factor whereas electrical degradation would be less effective.

UV Light Induced Photocatalytic Degradation of Cyanides in Aqueous Solution over Modified $TiO_2$

  • Kim, Hyeong Ju;Kim, Jae Hyeon;Lee, Cheong Hak;Hyeon, Taek Hwan;Choe, Won Yong;Lee, Ho In
    • Bulletin of the Korean Chemical Society
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    • v.22 no.12
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    • pp.1371-1374
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    • 2001
  • Metal doping was adopted to modify TiO2 (P-25) and enhance the photocatalytic degradation of harmful cyanides in aqueous solution. Ni, Cu, Co, and Ag doped TiO2 were found to be active photocatalysts for UV light induced degradation of aqueous cyanides generating cyanate, nitrate and ammonia as main nitrogen-containing products. The photoactivity of Ni doped TiO2 was greatly affected by the state of Ni, that is, the crystal size and the degree of reduction of Ni. The modification effects of some mixed oxides, that is, Ni-Cu/TiO2 were also studied. The activity of Ni-Cu/TiO2 for any ratio of Cu/Ni was higher than that of Ni- or Cu-doped TiO2, and the catalyst at the Cu/Ni ratio of 0.3 showed the highest activity for cyanide conversion.

The study on the effect of calcium chloride deicing agent and concrete compressive strength on scaling

  • Sung Hyun Eom;Seong Soo Kim;Jeong Bae Lee;Seung Ho Park
    • Journal of Ceramic Processing Research
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    • v.21 no.2
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    • pp.164-169
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    • 2020
  • This experimental study investigated the durability degradation of concrete exposed to freezing and thawing and chloride intrusion. In order to observe the degree of the degradation, 24 MPa, 35 MPa and 60 MPa concretes were used with 4% and 12% calcium chloride solution as freezing water for scaling resistance and freeze - thaw resistance tests. The results show that 24 MPa and 35 MPa concrete had a relatively large decrease in durability due to the freeze-thaw resistance and scaling resistance, but the 60 MPa concrete was not deteriorated significantly. In addition, when the concentration of the solution of calcium chloride was 4%, the degradation of durability was most remarkable. The results of this study suggest when concrete structures such as bridges or roads expose to the environmental conditions, appropriate measures such as increasing the designed standard strength of concrete need to be deliberated and additional studies should be conducted.