• Proceedings of the KSME Conference
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• 2000.04a
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• pp.49-54
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• 2000

Cr-Mo-V steel is widely used as a material for the turbine structural component in fossil power plants. It is well known that this material shows the various material degradation phenomenons such as temper embrittlement, carbide coarsening. and softening etc. or ins to the severe operation conditions as high temperature and high pressure. These deteriorative factors cause tile change of mechanical properties as reduction of fracture toughness. Therefor it is necessary to evaluate tile extent of degradation damage for Cr-Mo-V steel in life assessment of turbine structural components. In this paper. the electrochemical potentiokinetic reactivation(EPR) test in $50wt%-Ca(NO_3)_2$ solution is performed to develop the newly technique for degradation damage evaluation of Cr-Mo-V steel. The results obtained from the EPR test are compared with those in small punch(SP) tests recommended by semi-nondestructive testing method using miniaturized specimen. The evaluation parameters used in EPR test are tile reactivation current density$(I_R)$ and charge$(Q_{RC})$ reactivation rate$(I_R/I_{Crit},\;Q_R/Q_{Crit})$. The results suggest that $I_R/I_{Crit}$ in these parameters shows a good correlation with SP test results.

• Journal of the Korean Society of Food Science and Nutrition
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• v.19 no.4
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• pp.301-304
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• 1990

Factors affecting thermal inactivation and reactivation of korean radish peroxidase were inves-tigated,. The enzyme was stable below pH4.0 and above pH 8.0 The thermostablity of the enzyme was increased by addition of glucose sodium chloride and albuminl The inactivated enzyme by heat treatment was reactivated at room temperaturem The optimal pH for reactivation of the enzyme was pH of 9.0 The reactivation rate of the enyme was not afected by addition of glucose sodium chloride and albumin, The reactivation was completely inhibited by addition of sulfhydryl reagent such as dithiothreitol.

• Toxicological Research
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• v.4 no.1
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• pp.47-53
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• 1988

Cholera toxin and dibutyryl cyclic adenosine 3', 5'-monophosphate(db-cAMP) increased the rate and number of infections units produced in the in vitro reactivation of latent herpes simplex virus, whereas adenosine diminished them. cAMP concentration in latently infected trigeminal ganglia of mice was greatly increased by cholera toxin but was not affected by adenosine.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.7
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• pp.1241-1249
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• 2002

The extent of materials deterioration can be evaluated accurately by mechanical test such as impact test or creep test. But it is almost impossible to extract a large test specimen from in-service components. Thus material degradation evaluation by non-destructive method is earnestly required. In this paper, the material degradation for virgin and several aged materials of a Cr-Mo-V steel, which is an candidated as structural material of the turbine casing components for electric power plant, is nondestructively evaluated by reactivation polarization testing method. And, the results obtained from the test are compared with those in small punch(SP) tests recommended as a semi-nondestructive testing method using miniaturized specimen. In contrast to the aged materials up to 1,000hrs which exhibit the degradation behaviors with increased ${\Delta}[DBTT]_{SP}$, the improvement of mechanical property can be observed on the 2,000hrs and 3,000hrs aged materials. This is because of the softening of material due to the carbide precipitation, the increase of ferritic structures and the recovery of dislocation microstructure by long-time heat treatment. The reactivation rates($I_R/I_{Crit},\;Q_R/Q_{Crit}$) calculated by reactivation current densityt ($I_R$) and charge($Q_R$) in the polarization curves exhibit a good correlation with ${\Delta}[DBTT]_{SP}$ behaviors.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.2
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• pp.300-312
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• 1993

The material deterioration of service-exposed boiler tube steels in fossil power plant was evaluated by using the electrochemical technique namely, modified electrochemical potentiokinetic reactivation(EPR). It was focused that the passivation of Mo$_{6}$C carbide which governs the mechanical properties of Mo alloyed steels did not occur even in the passivity region of steel in sodium molybdate solution and the reactivation peak current (Ip) observed as the result of non-passivation indicating the precipitation of Mo$_{6}$C carbides. To obtain the optimal test conditions for the field test by using the specially designed electrochemical cell, the effects of scan rate, the surface roughness and the pH of electrolyte on Ip value were also investigated. Furthermore, the change of mechanical properties occurred during the long time exposure at high temperature was evlauated quantitatively by small punch(SP) tests and micro hardness test taking account of the metallurgical changes. It is known that reactivation peak current (Ip) has a good relationship with Larson-Miller Parameter(LMP) which represents the information about material deterioration occurred at high temperature environment. In addition it was possible to estimate the ductile-brittle transition temperature (DBTT) by means of the SP test. The Sp test could be, therefore, suggested as a reliable test method for evaluating the material degradation of boiler tube steels. From the good correaltion between the SP DBTT and Ip values shown in this study, it was knows that the change of mechanical properties could be evaluated non-destructively by measurring only Ip values.ues.

• Biomedical Science Letters
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• v.17 no.4
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• pp.305-311
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• 2011

Heart rate recovery (HRR) immediately after a treadmill exercise test is a function of vagal reactivation. A delayed heart rate recovery is associated with an increased risk for overall cardiovascular mortality. The purpose of this study is to find out if metabolic syndrome is associated with autonomic nerve function and exercise capacity in healthy adults. We measured the treadmill exercise capacity (METs) and heart rate recovery in 119 subjects through a medical checkup at $J$ General Hospital. The metabolic syndrome was defined according to the National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) criteria. The value for the HRR was defined as the difference between the heart rate obtained during the peak exercise and the heart rate obtained at first minute during the recovery period. The subjects with the metabolic syndrome had significantly lower exercise duration ($9.6{\pm}1.5$ vs $8.7{\pm}1.4$), METs ($11.6{\pm}1.7$ vs $10.4{\pm}2.5$), and HRR ($37.5{\pm}14.3$ vs $27.1{\pm}8.9$). The waist circumference in subjects with the metabolic syndrome was more strongly correlated with HRR ($r$=-.517, $P$ <.001) than in normal subjects. Furthermore, delayed HRR was associated with high resting heart rate and increased waist circumference ($P$=.032, $P$ <.001, respectively). In conclusion, delayed HRR during the first minute after a treadmill exercise test was associated with the metabolic syndrome risk factors. Delayed HRR was also associated with high resting heart rate and increased waist circumference.

• The Korean Journal of Pharmacology
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• v.22 no.2
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• pp.123-127
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• 1986

n-Butyrate (n-BT A) increased the rate and number of infectious units produced in the in vitro reactivation of latent herpes simplex virus. While the mechanism of action of n-BT A is obscure, a continuous presence of n-BT A is necessary for its inductive effect.

• Korean Journal of Pharmacognosy
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• v.23 no.2
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• pp.106-114
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• 1992

The acute toxicity and the effect of steam distillate obtained from several plant mixtures (G-3) on the reactivation of brain, lung, and blood acetylcholinesterase (AChE) activity, and recovery from other toxic symptoms following intoxication by organophosphate pesticides were investigated in mice and mudfish. Administration of G-3 $(50{\sim}100\;ml/kg,\;i.p.)$ immediately or 30 min prior to Diazinon or Sumithion treatments, respectively, resulted in a significant reactivation of AChE activity in brain, lung, and blood, their potencies being almost equipotent to those of 2-PAM, one of well-known antidotes. G-3 itself exhibited almost no acute toxicity even at the highest dose employed, and without effect on the inhibition of hepatic drug metabolism function following organophosphate administrations. G-3 showed a significant diminution of the death rate in mudfish as well as in mice intoxicated by Diazinon.

• Tunnel and Underground Space
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• v.29 no.3
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• pp.197-213
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• 2019

We simulated the fault reactivation experiment conducted at 'Main Fault' intersecting the low permeability clay formations of Mont Terri Underground Research Laboratory in Switzerland using TOUGH-FLAC simulator. The fluid flow along a fault was modelled with solid elements and governed by Darcy's law with the cubic law in TOUGH2, whereas the mechanical behavior of a single fault was represented by creating interface elements between two separating rock blocks in FLAC3D. We formulate the hydro-mechanical coupling relation of hydraulic aperture to consider the elastic fracture opening and failure-induced dilation for reproducing the abrupt changes in injection flow rate and monitoring pressure at fracture opening pressure. A parametric study was conducted to examine the effects of in-situ stress condition and fault deformation and strength parameters and to find the optimal parameter set to reproduce the field observations. In the best matching simulation, the fracture opening pressure and variations of injection flow rate and monitoring pressure showed good agreement with field experiment results, which suggests the capability of the numerical model to reasonably capture the fracture opening and propagation process. The model overestimated the fault displacement in shear direction and the range of reactivated zone, which was attributed to the progressive shear failures along the fault at high injection pressure. In the field experiment results, however, fracture tensile opening seems the dominant mechanism affecting the hydraulic aperture increase.

• Journal of Microbiology and Biotechnology
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• v.16 no.3
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• pp.414-422
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• 2006

Before applying PVA bio-beads to practical biological treatment of nitrate-containing wastewater, their characteristics were examined. PVA bio-beads could steadily produce nitrogen gas from nitrate for 28 batches with 0.04 ml/l/h of the maximum gas production rate; however, the maximum gas production rate dropped remarkably thereafter with apparent deformation of beads. Addition of 2.2% solution containing 1% casamino acid, 1% yeast extract, 0.1% mineral solution, and 0.1% vitamin solution to the culture medium resulted in not only recovery of activity of deactivated beads, but also a higher rate of gas production. Calculation of economic benefit for the use of bio-beads in a long-run operation indicated that reactivation of bio-beads by chemicals had economical advantages over packing new bio-beads in the system. The continuously stirred bioreactor exhibited a satisfactory performance at HRT of 20.0 h. With a 9.5 mg $NO_{3}^{-}N/l/h$ nitrate removal rate, nitrate could completely be removed without nitrite accumulation. The use of PVA bio-beads in nitrate removal appears very promising.