• 터널과지하공간
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• 제30권4호
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• pp.335-358
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• 2020

본 연구에서는 TOUGH-FLAC 연동해석기법을 통해 단층의 수리역학적 거동을 평가할 수 있는 수치해석 모델을 제안하였다. 이는 국제공동연구 DECOVALEX-2019 Task B의 일환으로 수행되었으며, 불투수성 암반 내 유체 주입으로 인한 단층의 재활성을 예측하고 주변 암반의 수리역학적 안정성을 평가할 수 있는 해석모델을 개발하는 데에 그 목적이 있다. 본 연구에서는 TOUGH2 수리유동모델과 FLAC3D의 역학적 인터페이스 모델의 연동을 통해 단층의 역학적 거동을 보다 합리적으로 구현할 수 있는 해석기법을 제안하고, 벤치마크 해석과 스위스 Mont Terri 지하연구시설 현장시험에 적용하여 그 타당성과 유효성을 검증하였다. 개발된 해석 모델은 유체의 주입으로 인한 단층 내 압력 분포의 발달, 역학적 변형에 따른 수리간극의 변화, 변위와 응력 등 단층의 수리역학적 거동을 적절히 재현할 수 있는 것으로 나타났다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.110-110
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• 2018

여러 니켈합금 중 인코넬 600은 원전 가압경수로(PWR)의 튜브 재료로 널리 사용되는 재료이다. 스테인리스강과 비교하여 우수한 내식성과 기계적 특성으로 인해 화학설비, 발전설비, 그리고 해양설비 등과 같은 여러 산업분야에서도 널리 사용되고 있다. 그러나 가압경수로용 증기 발생기의 튜브 재료와 같은 특수 환경에서 예민화에 따른 입계부식 및 입계응력부식 등의 문제가 흔히 보고되고 있다. 이러한 내구성 문제는 설비 및 장비의 수명, 내구성 그리고 안정성 등의 치명적인 영향을 미친다. 따라서 용접, 열처리, 그리고 가공과정에서 발생하는 Inconel 600의 예민화 및 입계부식에 관한 연구가 활발히 진행되고 있다. 그러나 100시간 이상 장시간 열화된 시편에 대한 예민화 연구는 전무한 실정이다. 본 연구에서는 장시간 열화된 Inconel 600의 예민화를 평가하기 위해 최대 1,000시간까지 열화를 실시하였으며, 이에 대한 평가방법으로 Double-Loop Electrochemical Potentiokinetic Reactivation(DL-EPR) 시험법을 적용하였다. 본 실험에서 사용된 인코넬 600의 화학성분(wt, %)은 0.01 C, 0.05 Si, 0.14 Mn, 15.3 Cr, 0.5 Cu, 0.015 S, 그리고 나머지는 Ni 이다. 예민화 평가를 위한 등온 열화는 전기열처리로를 이용하여, $550^{\circ}C$와 $650^{\circ}C$에서 최대 1000시간까지 실시하였다. 열화에 따른 미세조직 변화는 scanning electron microscope와 energy dispersive x-ray spectroscopy를 이용하여 실시하였다. DL-EPR 실험은 $25^{\circ}C$의 0.1M $H_2SO_4$ + 0.001M KSCN(potasium thiocyanate) 수용액 하에서 실시하였으며, 분극은 OCP로부터 600 mV(SSE vs.)까지 1.67mV/s 주사속도로 forward scan을 실시 후, 동일한 속도로 OCP까지 reverse scan을 실시하였다. Degree Of Sensitization(DOS)값은 anodic scan peak($I_a$) 값과 reverse scan peak($I_r$) 값의 비로 산출하였다. $$i.e.\;DOS=I_r/I_a{\times}100$$. 그 결과, 온도 변수에 따른 Inconel 600강의 예민화 거동은 서로 상이한 경향을 나타내었다. $550^{\circ}C$의 경우, 열화가 진행됨에 따라 DOS값은 급격하게 증가하는 경향을 나타냈다. 반면, $650^{\circ}C$에서는 일정시간 이후부터 Cr 확산 현상에 의한 탈 예민화 현상이 관찰되었다.

• Corrosion Science and Technology
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• 제2권3호
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• pp.117-126
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• 2003

Due to excellent corrosion resistance and mechanical properties, austenitic stainless steel is widely used as the material for chemical plants. nuclear power plants, and food processing facilities. But, the zone affected by heat in the range of 400 to $800^{\circ}C$ during welding loses corrosion resistance and tensile strength since Cr-carbide precipitation like $Cr_{23}C_6$ forms at the grain boundary and thereby takes place the intergranular corrosion. In this study, AISI 304 stainless steel with the added Nb of 0.3 to 0.7 wt% was solutionized at $1050^{\circ}C$ and sensitized at $650^{\circ}C$. Specimen was welded by MIG. The phase and the microstructure of the specimens were examined by an optical microscope, a scanning electron microscope, and a x-ray diffractometer. The corrosion characteristics of specimens were tested by electrolytic etching and by double loop electrochemical potentiokinetic reactivation method(EPR) in the mixed solution of 0.5M $H_2SO_4$ + 0.01M KSCN. The melting zone had dendritic structure constituted of austenitic phase and $\delta$-ferrite phase. Cr carbide at the matrix did not appear, as Nb content increased. At the grain boundaries of the heat affected zone, the precipitates decreased and the twins appeared. The hardness increased, as Nb content increased. The hardness was highest in the order of the heat affected zone>melted zone>matrix. According to EPR curve, as the Nb content decreased, the reactivation current density(Ir) and the activation current density(la) were highest in the order of the melted zone

• 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.

• IMMUNE NETWORK
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• 제12권2호
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• pp.58-65
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• 2012

Background: A cell line with transfected Wilms' tumor protein 1 (WT1) is has been used for the preclinical evaluation of novel treatment strategies of WT1 immunotherapy for leukemia due to the lack of appropriate murine leukemia cell line with endogenous WT1. However, silencing of the transgene occurs. Regarding the effects of hypomethylating agents (HMAs) on reactivation of silenced genes, HMAs are considered to be immune enhancers. Methods: We treated murine WT1- transfected C1498 (mWT1-C1498) with increasing doses of decitabine (DAC) and azacitidine (AZA) to analyze their effects on transgene reactivation. Results: DAC and AZA decreased the number of viable cells in a dose- or time-dependent manner. Quantification of WT1 mRNA level was analyzed by real-time polymerase chain reaction after mWT1-C1498 treated with increasing dose of HMA. DAC treatment for 48 h induced 1.4-, 14.6-, and 15.5-fold increment of WT1 mRNA level, compared to untreated sample, at 0.1, 1, and $10{\mu}M$, respectively. Further increment of WT1 expression in the presence of 1 and $10{\mu}M$ DAC was evident at 72 h. AZA treatment also induced up-regulation of mRNA, but not to the same degree as with DAC treatment. The correlation between the incremental increases in WT1 mRNA by DAC was confirmed by Western blot and concomitant down-regulation of WT1 promoter methylation was revealed. Conclusion: The in vitro data show that HMA can induce reactivation of WT1 transgene and that DAC is more effective, at least in mWT1-C1498 cells, which suggests that the combination of DAC and mWT1-C1498 can be used for the development of the experimental model of HMA-combined WT1 immunotherapy targeting leukemia.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.537-540
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• 2001

A parallel TBF system that is consisted of two TBFs was developed f ‘ or the long-term treatment of gas-phase trichloroethylene (TCE). Each TBF was operated for TCE degradation or reactivation in a parallel mode, and the effect of switching time and operation variables between the two reactors was investigated. Within 12 hr after switching from TCE degradation to reactivation mode, the MO activity increased up to the initial level. More than 50 % of TCE was degraded for feed concentrations ranging from 5 to 17 ppmv, and completely 100 % removed at concentration of less than 5 ppmv, while TCE removal decreased severely over 28 ppmv. In various empty bed retention times (EBRTs), ranging 상 om 5.2 to 10.7 min, the optimal EBRT was 10.7 min that TCE conversion achieved more than 50 %. For the inlet loading below 23.4 mg TCE/L/day, TCE was entirely removed. The maximal TCE elimination capacity in this system was about 66.63 mg TCE/L/day. During the continuous treatment of TCE over 3 months, TCE removal efficiency was maintained at the range of about 50 %. In these results, the parallel TBF system can be available for the continuously TCE biodegrading operation.

• 식물조직배양학회지
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• 제27권4호
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• pp.245-258
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• 2000

Somatic embryogenesis has become a major tool in the study of plant embryology, as it is possible in culture to manipulate cells of many plant species to produce somatic embryos in a process that is remarkably similar to zygotic embryogenesis. Traditionally, the process has been studied by an examination of the ex vitro factors which influence embryo formation. Later structural, physiological and biochemical approaches have been applied. Host recently, molecular tools are being used. Together, these various approaches are giving valuable information on the process. This article gives an overview of somatic embryogenesis by reviewing information on the morphogenesis, physiology, biochemistry and molecular biology of the process. Topics covered include a brief description of the factors involved in the production of embryogenic cells. Carrot cell suspension is most commonly used, and the development of a high frequency and synchronous system is outlined. At the physiological and biochemical lev-els various topics, including the reactivation of the cell cycle, changes in endogenous growth regulators, amino acid, polyamine, DNA, RNA and protein metabolism, and embryogenic factors in conditioned medium are all discussed. Lastly, recent information on genes and molecular markers of the embryogenic process are outlined. Somatic embryogenesis, the best example of totipotency in plant cells, is not only an important tool in studies in basic biology, but is potentially of equal significance in the micropropagation of economically important plants.

• 지질공학
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• 제28권2호
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• pp.175-182
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• 2018

본 논문에서는 이산화탄소 지중저장 시험이 진행 중인 포항 영일만 지역의 지질학적, 암석물리학적, 지질역학적 특성에 대한 분석 결과를 보고한다. 대상 저류층은 영일만 해상 퇴적층 750 m 심도에 다공질, 투수성의 사암/역암층으로 존재하며 상부에 두꺼운 이암층으로 덮고 있다. 해상에 굴착된 탐사시추공에서 측정된 응력 값은 이 지역이 주향이동 단층운동에 유리한 응력체계를 보인다. 측정된 응력 값에 기반하여 다양한 유형의 저류층 파쇄압력, 주변 단층의 전단활성 압력 등에 대한 정보에 대해 고찰하며 분석하였다.

• The Korean Journal of Pain
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• 제26권3호
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• pp.242-248
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• 2013

Varicella (chickenpox) is a highly contagious airborne disease caused by primary infection with the varicella zoster virus (VZV). Following the resolution of chickenpox, the virus can remain dormant in the dorsal sensory and cranial ganglion for decades. Shingles (herpes zoster [HZ]) is a neurocutaneous disease caused by reactivation of latent VZV and may progress to postherpetic neuralgia (PHN), which is characterized by dermatomal pain persisting for more than 120 days after the onset of HZ rash, or "well-established PHN", which persist for more than 180 days. Vaccination with an attenuated form of VZV activates specific T-cell production, thereby avoiding viral reactivation and development of HZ. It has been demonstrated to reduce the occurrence by approximately 50-70%, the duration of pain of HZ, and the frequency of subsequent PHN in individuals aged ${\geq}50$ years in clinical studies. However, it has not proved efficacious in preventing repeat episodes of HZ and reducing the severity of PHN, nor has its long-term efficacy been demonstrated. The most frequent adverse reactions reported for HZ vaccination were injection site pain and/or swelling and headache. In addition, it should not be administrated to children, pregnant women, and immunocompromised persons or those allergic to neomycin or any component of the vaccine.

• Journal of Microbiology and Biotechnology
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• 제10권1호
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• pp.35-42
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• 2000

Reaction characteristics of 4-methylcatechol 2,3-dioxygenase (4MC230) purified from Pseudomonas putida SU10 with a higher activity toward 4-methylcatechol than catechol or 3-cethylcatechol were studied by altering their physical and chemical properties. The enzyme exhibited a maximum activity at pH 7.5 and approximately 40% at pH 6.0 for 4-methylcatechol hydrolysis. The optimum temperature for the enzyme was around $35^{\circ}C$, since the enzyme was unstable at higher temperature. Acetone(10%) stabilized the 4MC230. The effects of solvent and other chemicals (inactivator or reactivator) for the reactivation of the 4MC230 were also investigated. Silver nitrate and hydrogen peroxid severely deactivated the enzyme and the deactivation by hydrogen peroxide severely deactivated the enzyme and the deactivation by hydrogen peroxide was mainly due to the oxidation of ferrous ion to ferric ion. Some solvents acted as an activator and protector for the enzyme from deactivation by hydrogen peroxide. Ascorbate, cysteine, or ferrous ion reactivated the deactivated enzyme by hydrogen peroxide. The addition of ferrous ion together with a reducing agent fully recovered the enzyme activity and increased its activity abut 2 times.