• Journal of Magnetics
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• 제22권1호
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• pp.34-42
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• 2017

Material defects in the Steam Generator Tubes (SGT) of sodium cooled fast breeder reactor (PFBR) can lead to leakage of water into sodium. The water and sodium reaction will lead to major accidents. Therefore, the examination of steam generator tubes for the early detection of defects is an important requirement for safety and economic considerations. In this work, the Magnetic Flux Leakage (MFL) based Non Destructive Testing (NDT) technique is used to perform the defect detection process. The rectangular notch defects on the outer surface of steam generator tubes are modeled using COMSOL multiphysics 4.3a software. The obtained MFL images are de-noised to improve the integrity of flaw related information. Grey Level Co-occurrence Matrix (GLCM) features are extracted from MFL images and taken as input parameter to train the neural network. A comparative study on characterization have been carried out using feed-forward back propagation (FFBP) and cascade-forward back propagation (CFBP) algorithms. The results of both algorithms are evaluated with Mean Square Error (MSE) as a prediction performance measure. The average percentage error for length, depth and width are also computed. The result shows that the feed-forward back propagation network model performs better in characterizing the defects.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제31회 추계학술대회논문집
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• pp.145-148
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• 2008

현재 항우연에서 개발 중인 우주발사체 터보펌프에 사용되는 터빈은 단단 충동터빈을 적용하고 있다. 우주발사체의 안정성을 위해 팁 간극을 비교적 많이 허용하고 있는데, 효율적인 면에서는 반동터빈 보다 다소 뒤지지만, 높은 출력비를 가지는 충동터빈이 팁 간극이 커질 때 어떤 효율경향을 나타내는지 알아보는 일은 의미 있는 일이다. 실험은 아음속 조건에서 실험하였고, 팁 간극을 각각 코드기준 1%$\sim$20%일 경우 충동과 반동 각각의 경우에 대하여 하류 전압손실을 측정하였다. 측정결과 팁 간극이 10%보다 더 커지면, 충동터빈이 오히려 전압손실량이 반동터빈보다 더 작아진다. 이것은 팁 간극이 비교적 큰 조건에서 충동터빈이 반동터빈보다 효율이나 출력비 면에서 더 나은 성능을 나타냄을 의미한다.

• Korean Chemical Engineering Research
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• 제52권6호
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• pp.713-719
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• 2014

4성분계 다중반응이 반응증류 탑 내에서 발생할 때 증류거동의 변화를 시각화 방법을 통해 분석하였다. 시각화 방법이란 단순 증류의 물질수지에 각 반응에 의한 벡터를 추가하고 이를 공간상에 표현하는 것으로 각 단에서 혼합물의 조성 변화 및 반응의 진척도를 직관적으로 알 수 있다. 또한 이를 통해 주어진 운전조건에서 필요한 총 단수 및 최적반응 단의 위치를 결정할 수 있다. 본 연구에서는 에틸렌글리콜(Ethylene glycol) 생산공정을 시각화 방법을 통해 분석하였다. 제안된 시각화 방법을 사용하여 복잡한 실험이나 공정모사 없이 4성분계 다중반응증류 공정에 대한 타당성 평가 및 분석이 가능하다.

• 생명과학회지
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• 제18권8호
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• pp.1023-1030
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• 2008

SIPK와 WIPK의 상위 단계 인산화 효소로 알려진 NtMEK2가 DEX 유도성 시스템에 의해 밝혀졌다. 이 NtMEK2 유전자가 지속적으로 활성화된 돌연변이체인 $NtMEK2^{DD}$의 발현은 SIPK와 WIPK를 활성화 시켜 주므로 과민감 반응과 같은 세포 괴사를 야기하는 것으로 나타나 NtMEK2-SIPK/WIPK 체계가 담배에서 방어 반응을 조절하고 있음을 알 수 있었다. 그러나 NtMEK2-SIPK/WIPK 체계에 의해서 조절 되는 하위 기질이나 방어관련 유전자들에 대한 연구는 아직 미비한 상태이다. 그래서 본 연구는 NtMEK2-SIPK/WIPK 체계에 매개되는 하위 유전자들을 분리하기 위하여 $NtMEK2^{DD}$ 형질전환 식물체를 이용해 ACP에 기초한 DDRT-PCR을 수행하였다. 그 결과 본 연구를 통해 처음으로 pI2-4, MTS2, SINA, CDM1, HRGP 및 DEG45를 포함해 여섯 개의 DEG들을 선발하였다. 이 유전자들의 발현은 $NtMEK2^{DD}$ 형질전환에서 다시 확인하였으며 특히 pI2-4, CDM1, HRGP의 유전자 발현은 다른 유전자들과 비교해 볼 때 살리실산과 담배모자이크바이러스에 강하게 반응하여 증폭됨을 알 수 있었다. 이러한 결과를 볼 때 NtMEK2-SIPK/WIPK 체계에 의해 조절되는 세 개의 유전자는 병저항성에 관여하고 있음을 제시한다 하겠다.

• Tuberculosis and Respiratory Diseases
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• 제74권6호
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• pp.264-268
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• 2013

Background: Idiopathic pulmonary fibrosis (IPF) is a lethal pulmonary fibrotic disease. In general, the exaggerated activation of the coagulation cascade has been observed during initiation or maintenance of the fibrotic disease. In our recent study, immunohistochemical expression of protease-activated receptor-2 (PAR-2), which plays a key role in coagulation cascade, was observed in surgical specimen of IPF patients, and associated with poor clinical outcome. The aim of this study was to evaluate the overexpression of PAR-2 in inflammatory cells from peripheral blood and bronchoalveolar lavage fluid in IPF patients. Methods: From May 2011 to March 2012, IPF patients and controls were enrolled in Seoul National University Hospital. Peripheral blood and bronchoalveolar lavage fluid were collected for analysis of PAR-2 expression. Flow cytometry and reverse transcription polymerase chain reaction were used for PAR-2 receptor and mRNA assessment. Results: Twelve IPF patients and 14 controls were included in this study. Among them, flow cytometry analysis was conducted from 26 peripheral blood (patient group, 11; control group, 13) and 7 bronchoalveolar lavage fluid (patient group, 5; control group, 2). The expression of PAR-2 receptor was not different between patient and control groups (p=0.074). Among all 24 population, PAR-2 mRNA assessment was performed in 19 persons (patient group, 10; control group, 9). The mRNA expression of PAR-2 was not significant different (p=0.633). Conclusion: In IPF patients, PAR-2 receptor and mRNA expression were not different from control group.

• Bulletin of the Korean Chemical Society
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• 제29권1호
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• pp.89-93
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• 2008

The key step in a strategy for the synthesis of (+)-lactacystin involving photocyclization reaction of a cyclopenta-fused pyridinium salt has been probed by using a model substrate. Observations made in this effort led to the discovery of a highly unusual cascade process that leads to stereoselective formation of an interesting tricyclic carbamate. The results of this study are presented and discussed in the context of a (+)-lactacystin synthetic approach.

• Journal of Plant Biology
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• 제36권2호
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• pp.171-176
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• 1993

Protein kinase C, a protein related in PI cascade, was partially purified from the cytosol protein of etiolated plants of Glycine max by DEAE-52 cellulose chromatography and phenylsepharose chromatography. When the DEAE column was eluted with 0-0.8 M linear gradient KCl, tow fractions were found that increased the phosphorylation of histon H1 about five and nine-fold in the presence of 5 $\mu\textrm{g}$/mL phosphatidylserine and 0.5 $\mu\textrm{g}$/mL diolein, respectively. These fractions were used as DEAE pool. The reaction eluted with relatively high concentration of KCl was loaded on phyenylsepharose column with 5 mM CaCl2 and eluted with 1 mM EGTA. A fraction contained the protein kinase C, which increased the phosphorylation of the histon H1 was fractionated. To determine the molecular weight of PKC, the fraction eluted from phenylsepharose column was analyzed by 5~15% polyacrylamide gel electrophoresis after concentrated with the Amicon membrane (YM10). That revealed two bands corresponding to 60 and 65 kGy by silver staining of the gel, respectively.

• 한국산학기술학회논문지
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• 제19권6호
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• pp.154-159
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• 2018

도시가스 회사는 설비의 유지보수 및 점검을 수행할 경우에 가스를 방산하는 경우가 있는데, 가스누출 오인으로 신고 및 주민불안이 발생하게 됨에 따라 활성물질을 통한 천연가스의 부취냄새를 효과적으로 탈취하는 방법을 연구하는데 그 목적을 두었다. 본 연구에서는 천연가스 부취냄새 탈취를 위해 활성물질인 차아염소산나트륨을 이용한 산화법을 통해 천연가스 부취제와 활성물질간 효율적 혼합방법을 위해 간이 탈취방산장치를 제작하여 현장에서 실험을 통해 부취농도를 확인하였다. 탈취실험장치의 기본원리는 방산되는 가스(0.8~1.0MPa)의 에너지를 이용하여 활성물질용액이 첨가되도록 하여 가스 내 부취제와 혼합과정을 거친 후 방출구를 통해 대기로 방산된다. 도시가스 부취제의 활성물질인 차아염소산나트륨을 이용하여 산화반응을 통해 벤츄리와 혼합용기의 직렬연결방식을 적용하여 제작한 장치를 통해 현장에서 효과적으로 부취냄새를 제거할 수 있었다. 하지만, 실질적인 효과를 거두기 위해서는 도시가스의 다량과 고압에서 방산되는 조건에서의 적용하는 문제해결 과제가 남아 있다.

• BMB Reports
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• 제34권6호
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• pp.544-550
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• 2001

In pre-transplant total-body irradiation (TBI), the lung is a critical dose-limiting organ. Also, the possible role of oxidative stress was suggested in the development of TBI-induced lung damage. This study explores the association between TBI-induced oxidative stress and the induction of lung pathogenesis by investigating TBI-induced oxidative stress in the lungs of male C57BL/6 mice after a single dose of 10 Gy TBI. We showed significant increases of reactive oxygen species (ROS) formation and lipid peroxidation, and also a depletion and oxidation of glutathione after TBI. There is evidence that pretreatment with 1,10-phenanthroline (o-phen) significantly reduces oxidative stress in the lung. This indicates that the TBI-induced ROS generation involves a metal-catalyzed Fenton-type reaction. A pretreatment of buthionine sulfoximine (BSO) augmented the glutathione depletion and oxidation, but had no effect on the ROS formation and lipid peroxidation up to 6 h after TBI. Histopathological features that are consistent with pneumonitis were observed in the BSO pretreated-mice 1 week after irradiation. The results suggest that TBI-induced oxidative stress in the lung involves a generation of ROS through a Fenton-type reaction. Also, glutathione plays an important inhibitory role in the radiation-induced lung pathogenesis by participating in the self-amplifying cascade subsequent to the ROS generation by irradiation.

• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1608-1612
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• 2012

Singlet oxygen ($^1O_2$) is an important species for oxidation in biological processes. $^1O_2$ is implicated in the genotoxic effect, and plays an important role in the cell-signaling cascade and in the induction of gene expression. However, the rapid detection of $^1O_2$ in biological environments with sufficient specificity and sensitivity is hampered by its extremely low emission probability. Here, a layer-by-layer (LbL) film of CdTe quantum dots (QDs), polymers, and ascorbate have been designed as a rapid, highly selective, and sensitive fluorescence probe for $^1O_2$ detection. Upon reaction with $^1O_2$, the probe exhibits a strong photoluminescence (PL) response even at trace levels. This remarkable PL change should enable the probe to be used for $^1O_2$ detection in many chemical and biological systems and as an environmental sensor.