• Title, Summary, Keyword: Degradation

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Development of experiment technology for assessment of shotcrete lining long-term degradation in tunnels (터널 숏크리트 라이닝의 장기 내구성 평가를 위한 실험기법 개발)

  • Lim, Jong-Jin;Shin, Hyu-Soung;Bae, Gyu-Jin
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.439-444
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    • 2005
  • Shotcrete lining is likely to be deteriorated due to the ground water which the lining is exposed to. Some tunnel collapses seemed to be affected by shotcrete degradation were reported. But there isn't any assessment method of shotcret long-term degradation. So, Experimental technology for shotcrete long-term degradation modeling was developed in this study. The shotcrete long-term degradation modeling, developed in other study in Korea Institute of Construction Technology, require the time-history of volume change. Digital strain observation system was used to acquire the time-history of volume change. To verify the Strain Observation Digital System, the measurement using the system was compared to the one using a micrometer. Through this process, The experiment for shotcrete long-term degradation modeling was set up.

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HAZARD ASSESSMENT OF CURRENT STATE OF VEGETATION DEGRADATION USING GIS, A CASE STUDY: SADRA REGION, IRAN

  • Masoudi, Masoud;Amiri, E.
    • Journal of Ecology and Environment
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    • v.36 no.1
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    • pp.49-56
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    • 2013
  • The entire land of Southern Iran faces problems arising out of various types of land degradation of which vegetation degradation forms one of the major types. The present work introduces a model developed for assessing the current status of hazard of vegetation degradation using Geographic Information System (GIS). This kind of assessment differs from those assessments based on vulnerability or potential hazard assessments. The Sadra watershed which covers the upper reaches of Marharlu basin, Fars Province, has been chosen for a hazard assessment of this type of degradation. The different kinds of data for indicators of current status of vegetation degradation were gathered from collecting of field data and also records of the governmental offices of Iran. Taking into consideration three indicators of current status of vegetation degradation the model identifies areas with different hazard classes. By fixing the thresholds of severity classes of the three indicators including per cent of vegetation cover, biomass production and ratio of actual biomass to potential biomass production, a hazard map for each indicator was first prepared in GIS. The final hazard map of current status of vegetation degradation was prepared by intersecting three hazards in the GIS. Results show areas under severe hazard class have been found to be widespread (89 %) while areas under moderate and very severe hazard classes have been found less extensive in the Sadra watershed. The preparation of hazard maps based on the GIS analysis of these indicators will be helpful for prioritizing the areas to initiate remedial measures.

Degradation Efficiency and Characterization of Lincomycin by Electron Beam Irradiation

  • Ham, Hyun-Sun;Cho, Hyun-Woo;Myung, Seung-Woon
    • Mass Spectrometry Letters
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    • v.5 no.3
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    • pp.89-93
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    • 2014
  • Lincomycin is one of the major species among the Pharmaceuticals and Personal Care Products (PPCPs) detected from the four major rivers in Korea. The structure characterization was performed of six degradation products of lincomycin formed under the irradiation of electron beam, and the degradation efficiency as a function of the various irradiation dose and sample concentration was investigated. Electron beam (10 MeV, 0.5 mA and 5 kW) experiments for the structural characterization of degradation products that are fortified with lincomycin, were performed at the dose of 10 kGy. The separation of degradation products and lincomycin was carried out using a C18 column ($2.1{\times}100$ mm, $3.5{\mu}m$), using gradient elution with 20 mM ammonium acetate and acetonitrile. The structures of six degradation products of lincomycin were proposed by interpretation of mass spectra and chromatograms by LC-MS/MS. The mass fragmentation pathways of mass spectra in tandem mass spectrometry were also proposed. Experiments were performed of the degradation efficiency as a function of the irradiation dose intensity and the initial concentration of lincomycin in an aqueous environment. In addition, increased degradation efficiency was observed with a higher dose of electron beam and lower concentration.

Thermal Degradation of Aqueous MEA Solution for CO2 Absorption by Nuclear Magnetics Resonance (핵자기공명분석법을 이용한 수용성 아민 CO2 흡수제인 MEA의 열적변성 분석)

  • CHOI, JEONGHO;YOON, YEOIL;PARK, SUNGYOUL;BAEK, ILHYUN;KIM, YOUNGEUN;NAM, SUNGCHAN
    • Transactions of the Korean hydrogen and new energy society
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    • v.27 no.5
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    • pp.562-570
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    • 2016
  • At the carbon dioxide capture process using the aqueous amine solution, degradation of absorbents is main factor to reducing the process performance. Also, degradation mechanism of absorbent is important for understanding the environmental risk, route of degradation products, health risk etc. In this study, the degradation products of MEA were studied to clarify mechanism in thermal degradation process. The degradation products were analyzed using a $^1H$ NMR (nuclear magnetic resonance) and $^{13}C$ NMR. The analysis methods used in this study provide guidelines that could be used to develop a degradation inhibitor of absorbent and a corrosion inhibitor.

Enzymatic Degradation of Leucine Enkephalin and $[D-Ala^2]$-Leucine Enkephalinamide in Various Rabbit Mucosa Extracts (토끼의 수종 점막 추출액중 로이신엔케팔린 및 [D-알라$^2]$-로이신엔케팔린아미드의 효소적 분해 특성)

  • Chun, In-Koo;Park, In-Sook
    • YAKHAK HOEJI
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    • v.38 no.5
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    • pp.530-543
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    • 1994
  • To study the feasibility of transmucosal delivery of leucine enkephalin (Leu-Enk) and $[D-ala^2]$-leucine enkephalinamide (YAGFL), their degradation extents and pathways in various rabbit mucosa extracts were investigated by high performance liquid chromatography. The degradation of Leu-Enk and YAGFL was observed to follow the first-order kinetics. The degradation half-lives of Leu-Enk in the nasal, rectal and vaginal mucosal extracts were 1.62, 0.37 and 1.12 hrs and those of YAGFL were 30.55, 9.70 and 6.82 hrs, respectively, indicating Leu-Enk was degraded in a more extensive and rapid manner than YAGFL. But the mucosal and serosal extracts of the same mucosa showed the similar degradation rates for both pentapeptides. The degradation was most rapid in the neutral pH and increasing concentrations of substrates retarded the degradation rates. The maior hydrolytic fragments of Leu-Enk were Des-Tyr-Leu-Enk and tyrosine, indicating the enzymatic hydrolysis by aminopeptidases. However, the data also suggested endopeptidases such as dipeptidyl carboxypeptidase and dipeptidyl aminopeptidase could play some role in the degradation of Leu-Enk. On the other hand, the hydrolytic fragments of YAGFL in all the mucosa extracts were mainly Tyr-D-Ala-Gly and Phe-Leu-Amide, demonstrating the hydrolytic breakdown by endopeptidases. The degradation pathways were further explored by concomitantly determining the formation of smaller metabolites of primary hydrolytic fragments of Leu-Enk and YAGFL in the mucosa extracts.

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Effects of Electron Acceptors and Acclimation on the Anaerobic Degradation of Benzene, Toluene, and meta-Xylene (Benzene, Toluene, meta-Xylene의 혐기성 분해에 미치는 전자수용체와 시료 적응의 영향)

  • Yoon, In-Kil;Kwon, O-Seob;Kim, Sang-Jin
    • Korean Journal of Microbiology
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    • v.34 no.3
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    • pp.96-100
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    • 1998
  • The effects of electron acceptors and acclimation of inoculum on the anaerobic degradation of benzene, toluene, and m-xylene (BTX) were investigated to enhance the rate of degradation by estuarine sediment inoculum. With the fresh sediment inocula, degradation of BTX ensued after a 10-week acclimation period, and 37~61% of benzene and 57~61% of toluene were degraded after 16 weeks. Sediments from heavily contaminated sites showed higher degradation rates of BTX. After a 6-month of acclimation, degradation onset rapidly from the time of BTX addition and no difference was found among the sediment inocula. Single compound of BTX was slowly degraded in the methanogenic conditions, however, the degradation of BTX mixture was slow in the denitrifying conditions. Although the degradation rate of m-xylene was the fastest among the components of BTX mixture, longer acclimation enhanced the degradation rate of BTX, especially that of benzene. When the culture fluids were tested with Microtox, anaerobic degradation of BTX reduced the toxicity of BTX as well.

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The Possible Mechanisms Involved in Citrinin Elimination by Cryptococcus podzolicus Y3 and the Effects of Extrinsic Factors on the Degradation of Citrinin

  • Zhang, Xiaoyun;Lin, Zhen;Apaliya, Maurice Tibiru;Gu, Xiangyu;Zheng, Xiangfeng;Zhao, Lina;Abdelhai, Mandour Haydar;Zhang, Hongyin;Hu, Weicheng
    • Journal of Microbiology and Biotechnology
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    • v.27 no.12
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    • pp.2119-2128
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    • 2017
  • Citrinin (CIT) is a toxic secondary metabolite produced by fungi belonging to the Penicillium, Aspergillus, and Monascus spp. This toxin has been detected in many agricultural products. In this study, a strain Y3 with the ability to eliminate CIT was screened and identified as Cryptococcus podzolicus, based on the sequence analysis of the internal transcribed spacer region. Neither uptake of CIT by cells nor adsorption by cell wall was involved in CIT elimination by Cryptococcus podzolicus Y3. The extracellular metabolites of Cryptococcus podzolicus Y3 stimulated by CIT or not showed no degradation for CIT. It indicated that CIT elimination was attributed to the degradation of intracellular enzyme(s). The degradation of CIT by C. podzolicus Y3 was dependent on the type of media, yeast concentration, temperature, pH, and initial concentration of CIT. Most of the CIT was degraded by C. podzolicus Y3 in NYDB medium at 42 h but not in PDB medium. The degradation rate of CIT was the highest (94%) when the concentration of C. podzolicus Y3 was $1{\times}10^8cells/ml$. The quantity of CIT degradation was highest at $28^{\circ}C$, and there was no degradation observed at 3$5^{\circ}C$. The study also showed that acidic condition (pH 4.0) was the most favorable for CIT degradation by C. podzolicus Y3. The degradation rate of CIT increased to 98% as the concentration of CIT was increased to $20{\mu}g/ml$. The toxicity of CIT degradation product(s) toward HEK293 was much lower than that of CIT.

EFFECTS OF SURFACTANTS ON THE FENTON DEGRADATION OF PHENANTHRENE IN CONTAMINATED SEDIMENTS

  • Jee, Sang-Hyun;Ko, Seok-Oh;Jang, Hae-Nam
    • Environmental Engineering Research
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    • v.10 no.3
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    • pp.138-143
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    • 2005
  • Laboratory batch experiments were conducted to evaluate the Fenton degradation rates of phenanthrene. Fenton reactions for the degradation of phenanthrene were carried out with aqueous and slurry phase, to investigate the effects of sorption of phenanthrene onto solid phase. Various types of surfactants and electrolyte solutions were used to evaluate the effects on the phenanthrene degradation rates by Fenton's reaction. A maximum 90% removal of phenanthrene was achieved in aqueous phase with 0.9% of $H_2O_2$ and 300 mg/L of $Fe^{2+}$ at pH 3. In aqueous phase reaction, inhibitory effects of synthetic surfactants on the removal of phenanthrene were observed, implying that surfactant molecules acted as strong scavenger of hydroxyl radicals. However, use of $carboxymethyl-{\beta}-cyclodextrin$ (CMCD), natural surfactant, showed a slight enhancement in the degradation of phenanthrene. It was considered that reactive radicals formed at ternary complex were located in close proximity to phenanthrene partitioned into CMCD cavities. It was also show that Fenton degradation of phenanthrene were greatly enhanced by addition of NaCl, indicating that potent radical ion ($OCI^-$) played an important role in the phenanthrene degradation, although chloride ion might be acted as scavenger of radicals at low concentrations. Phenanthrene in slurry phase was resistant to Fenton degradation. It might be due to the fact that free radicals were mostly reacting with dissolved species rather than with sorbed phenanthrene. Even though synthetic surfactants were added to increase the phenanthrene concentration in dissolved phase, low degradation efficiency was obtained because of the scavenging of radicals by surfactants molecules. However, use of CMCD in slurry phase, showed a slight enhancement in the phenanthrene degradation. As an alternative, use of Fenton reaction with CMCD could be considered to increase the degradation rates of phenanthrene desorbed from solid phase.

Evaluation of Material Degradation Using Electrical Resistivity Method (전기비저항법을 이용한 재료열화 평가)

  • Seok, Chang-Seong;Kim, Dong-Jung;Bae, Bong-Guk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.12
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    • pp.2995-3002
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    • 2000
  • The remaining life estimation for the aged components in power plants as well as chemical plants are very important beacuse mechanical properties of the components are degraded with time of service exposure in high temperature. Since it is difficult to take specimens from the operating components to evaluate mechanical properties of components nondestructive techniques are needed to estimate the degradation. In this study, test materials with 4 different degradation levels were prepared by isothermal aging heat treatment at 630$\^{C}$. And the DC potential drop method and destructive methods such as tensile, K(sub)IC and hardness tests were used in order to evaluate the degradation of 1-Cr-1Mo-0.25V steels. The objective of this study is to investigate the possibility of the application of DCPD method to estimated the material degradation, and to analyse the relationship between the electrical relationship between the electrical resistivity and the degree material degradation.

Design of Intelligent Insulation Degradation Sensor

  • Kim, Yi-Gon
    • International Journal of Fuzzy Logic and Intelligent Systems
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    • v.2 no.3
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    • pp.191-193
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    • 2002
  • Insulation aging diagnosis system provides early warning in regard to electrical equipment defects. Early warning is very important in that it can avoid great losses resulting from unexpected shutdown of the production line. For solving this problem, many researchers proposed a method that diagnose power plant by using partial discharge. In this paper, we design the intelligent sensor to diagnose insulation degradation state that uses a Microprocessor and Al. Proposed sensor has MCU that is used to diagnose insulation degradation and communicate with main IDD system. And we use a fuzzy model to diagnose insulation degradation.