• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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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.

• 한국식품영양과학회지
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• 제19권4호
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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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• 제4권1호
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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.

• 대한기계학회논문집A
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• 제26권7호
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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.

• 대한기계학회논문집
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• 제17권2호
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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.

• 대한의생명과학회지
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• 제17권4호
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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.

• 대한약리학회지
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• 제22권2호
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• pp.123-127
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• 1986

4-carbon fatty acid인 n-Butyrate(n-BTA)는 herpes virus의 일종인 Epstein-Bat virus(EBV)에 작용해서 잠복형인 EBV를 활성형태로 유도시키는 것으로 알려져 있다. 고로 본 실험에서는 mouse의 삼차신경절에 잠복하고 있는 HSV의 재활성화에 대한 n-BTA의 효과를 실험 관찰하였다. Pentobarbital로 마취시킨 mouse의 양쪽눈 각막을 30 gauge 주사바늘로 scarify한 후에 type I HSV(HSV-1) $10{\mu}1(1{\times}10^5$ plaque-forming units)를 각각 점안 감염시켰다. virus를 감염시킨 4주 후에 mouse의 삼차신경절을 적출하여 시험관 내에서 조직배양을 시행하였다. 조직배양시에 0. 1, 0. 25, 0.5. 1.0 그리고 2.0mM농도의 n-BTA를 첨가하였으며 1일, 2일, 3일간 각각 배양한 후 신경절을 연마하여 연마액내의 HSV-1 titer를Vero cell monolayer에서 plaque assay로 측정하였다. 1) n-BTA첨가군은 잠재성 HSV가 대조군에 비하여 현저하게 빨리 재활성화 되었고 재활성화되는 virus의 양도 현저히 증가되었다. 2) 24시간을 계속해서 n-BTA 각 농도를 첨가해서 배양할 군은 n-BTA 6시간 첨가 배양하고 새로운 배양액으로 갈아서 18시간 배양한 군에 비해 잠재성 virus의 재활성화가 현저히 증가되었다. 3) Gang1ionic latent HSV-1의 재 활성화에 영향을 미치는 각 농도의 n-BTA는 Vero cell의 monolayer에서의 HSV-1의 번식에는 아무런 영향을 미치지 않았다.

• 생약학회지
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• 제23권2호
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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.

• 터널과지하공간
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• 제29권3호
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• pp.197-213
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• 2019

본 연구에서는 TOUGH-FLAC 연동해석기법을 이용하여 Mont Terri 지하연구시설에서 수행된 단층 내 물 주입시험을 수치적으로 모델링하고, 단층의 재활성과 수리역학적 거동 특성을 살펴보았다. TOUGH2 해석에서는 단층을 Darcy의 법칙과 삼승법칙(Cubic law)을 따르는 연속체 요소로 모델링하였으며, FLAC3D 해석에서는 미끄러짐과 개폐가 허용되는 불연속 인터페이스 요소를 통해 모사하였다. 현장에서 획득한 단층의 균열개방압력(fracture opening pressure), 주입율, 모니터링 압력, 변위 곡선 등을 바탕으로, 단층의 탄성적 변형과 파괴에 의한 수직팽창 특성을 반영할 수 있는 수리간극모델과 수리역학 커플링 관계를 해석모델에 반영하였다. 한편, 현지응력 조건, 단층의 강도 및 변형 특성에 따른 파라미터 해석을 실시하여 각 입력변수가 해석 결과에 미치는 영향을 분석하였으며, 이를 통해 현장시험 결과를 가장 잘 재현할 수 있는 파라미터 조합을 선정하였다. 해석 결과, 균열개방압력에서 단층의 주입율과 모니터링 압력이 크게 증가하는 현상을 합리적으로 재현할 수 있었다. 하지만, 동일한 입력 변수 조건에서 단층의 전단변위와 파괴영역의 범위는 현장시험 결과에 비해 과대평가되는 결과를 보였다. 이는 해석모델에서는 고압의 주입조건에서 단층의 지속적인 전단파괴가 유도되는 반면, 현장에서는 수리간극의 변화가 전단 미끄러짐보다는 인장력에 의한 단층면의 개방(tensile opening)에 크게 의존하는 것으로 추정되기 때문이다.

• Journal of Microbiology and Biotechnology
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• 제16권3호
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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.