F.Mauriac와 연극

南宮 燃 카톨릭대학교 성심교정 1995 論文集 Vol.1 No.-

Mass Loss and Changes of Nutrients during Decomposition of Phragmites communis at the Fringe of Stream

Mun, Hueong-Tae,Namgung, Jeong,Namgung, Jeong-Hee-Namgung The Ecological Society of Korea 2000 Journal of Ecology and Environment Vol.23 No.2

Mass loss and changes of mineral nutrients during decomposition of Phragmites communis for 13 months from November 1998 to December 1999, were investigated at the fringe of stream at Boryeong, Chungnam Province in Korea. Plant materials, which were collected in November 1998. were divided into leaves, culms and rhizomes. Litterbags, 15${\times}$15 cm, were made of nylon mesh with 2-mm$^2$ holes. At 13 months after installation, remaining mass of leaves, culms and rhizomes was 29.0%, 57.4%, 20.6%, respectively. Mass loss rate of the culms was significantly lower than those of the leaves and rhizomes. The decay rate of leaves, culms and rhizomes was 1.21. 0.42 and 1.48 per year, respectively. Initial concentration of N, P, K, Ca and Mg of leaves. culms and rhizomes was 22.5, 9.0, 15.5 mg/g for N, 0.34. 0.10, 0.33 mg/g for P, 15.0, 12.5. 12.3 mg/g for K, 2.84. 0.80, 0.03 mg/g for Ca. 1.94. 0.97, 0.40 mg/g for Mg, respectively. Concentrations of nutrients were higher in leaves than in culms and rhizomes. Except for N and Mg in rhizomes, there was no immobilization period during the decomposition. In the case of remaining K and Ca, most are lost during the first 3 months. Without any suitable method for removal of dead part, eutrophication of freshwater may be accelerated by dead macrophytes.

Size distribution analysis of airborne wear particles released by subway brake system

Namgung, H.G.,Kim, J.B.,Kim, M.S.,Kim, M.,Park, S.,Woo, S.H.,Bae, G.N.,Park, D.,Kwon, S.B. Elsevier Sequoia [etc.] 2017 Wear: An international journal on the science and Vol.372 No.-

<P>Contributions of exhaust and non-exhaust sources to traffic-related particulate matter (PM) pollution in the atmosphere are almost identical and the most important non-exhaust source is known to be brake wear particles. In order to understand the properties and harmful effects of wear particles on people, accurate information on size distribution of brake wear particles is needed. Our previous study investigated the measured changes in size distribution of nanoparticles of 500 nm or smaller to understand the origin of nanoparticles due to temperature increases on the friction surface. The present study was intended to investigate the characteristics of size distribution (5.6 nm-32 mu m) of PM released under different braking conditions by using different instruments. The measurement results under 9 braking conditions using 3 different instruments showed that the size distribution chatacteristics of particles can be divided into two main types according to braking energy. The first type is of PM up to 10 mu m in size and with a peak number concentration at 0.2-0.75 mu m regardless of braking energy, while the second type is of PM around 10 nm in size generated only when braking energy increased and particles that increased up to 100 nm. In addition, we found that the size distributions measured by the optical particle counter (OPC) and the aerodynamic particle sizer (APS) were consistent by assuming a mean diameter ratio of two instruments. (C) 2016 Elsevier B.V. All rights reserved.</P>

A comparative study of histogram-based thresholding methods for the determination of cell-free layer width in small blood vessels

Namgung, Bumseok,Ong, Peng Kai,Wong, Yun Hui,Lim, Dohyung,Chun, Keyoung Jin,Kim, Sangho IOP Pub 2010 PHYSIOLOGICAL MEASUREMENT Vol.31 No.9

<P>We have recently proposed a computer-based method utilizing a thresholding algorithm (the Otsu method) to provide a convenient way of measuring the cell-free layer width <I>in vivo</I> and <I>in vitro</I>. However, this method does not seem to be a universal method that can be applied to all microvascular studies. Thus, we examined four different histogram-based thresholding algorithms (Otsu, intermode, minimum and second peak) to provide a technical suggestion on the selection of a suitable thresholding algorithm for the cell-free layer measurement. All the measurements were taken in microvascular flows in the rat cremaster muscle recorded with a high-speed camera. The width of the cell-free layer manually measured was compared with that determined by the automated method utilizing the four thresholding algorithms. With our experimental system, results showed that the cell-free layer width determined by the minimum algorithm was in best accordance with the manual measurement. We concluded that the accuracy of the automated methods for determination of the cell-free layer width would depend on the image quality, in particular on the contrast between the red blood cell core and background, which might differ due to the different microscopic setup. Therefore, one may need to examine several appropriate thresholding methods when selecting the best suitable algorithm for the experimental conditions.</P>

<i>Prunella vulgaris</i> Attenuates Diabetic Renal Injury by Suppressing Glomerular Fibrosis and Inflammation

Namgung, Seung,Yoon, Jung Joo,Yoon, Chi-Su,Han, Byung Hyuk,Choi, Eun Sik,Oh, Hyuncheol,Kim, Youn-Chul,Lee, Yun Jung,Kang, Dae Gill,Lee, Ho Sub Institute for Advanced Research in Asian Science a 2017 The American journal of Chinese medicine Vol. No.

<P>Diabetic nephropathy is both the most common complication and the leading cause of mortality associated with diabetes. <I>Prunella vulgaris</I>, a well-known traditional medicinal plant, is used for the cure of abscess, scrofula, hypertension and urinary diseases. This study confirmed whether an aqueous extract of <I>Prunella vulgaris</I> (APV) suppresses renal inflammation and fibrosis. In human mesangial cell (HMC), pretreatment of APV attenuated 25<TEX>$ \,$</TEX>mM HG-induced suppressed TGF-<TEX>$ \beta $</TEX> and Smad-2/4 expression; it increased the expression level of Smad-7. Connective tissue growth factor (CTGF) and collagen IV, fibrosis biomarkers, were significantly decreased by APV. APV suppressed inflammatory factors such as intracellular cell adhesion molecule-1 (ICAM-1) and monocyte chemoattractant protein-1 (MCP-1). APV inhibited activation and translocation of nuclear factor kappa-B (NF-<TEX>$ \kappa $</TEX>B) in HG-stimulated HMCs. Moreover, APV significantly improved HG-induced ROS in a dose-dependent manner. In diabetic rat models, APV significantly decreased blood glucose, blood urea nitrogen (BUN) and ameliorated plasma creatinine (PCr). APV reduced the PAS positivity staining intensity and basement membrane thickening in glomeruli of diabetic rats. Fibrosis related proteins such as collagen IV and TGF-<TEX>$ \beta $</TEX>1 were also inhibited by APV. These results suggest that APV has a significant protective effect against diabetic renal dysfunction including inflammation and fibrosis through disruption of the TGF-<TEX>$ \beta $</TEX>/Smad signaling. Therefore, APV may be useful in potential therapies that target glomerulonephritis and glomerulosclerosis, which lead to diabetic nephropathy.</P>

Weight Loss and Nutrient Dynamics during Leaf Litter Decomposition of Quercus variabilis and Pinus densiflora at Mt. Worak National Park

NamGung, Jeong,Han, A-Reum,Mun, Hyeong-Tae The Ecological Society of Korea 2008 Journal of Ecology and Environment Vol.31 No.4

Weight loss and nutrient dynamics of oak and pine leaf litter during decomposition were investigated from December 2005 through June 2008 at Mt. Worak National Park as a part of National Long-Term Ecological Research Program in Korea. The decay constant (k) of oak and pine leaf litter were 0.314 and 0.217, respectively. After 30 months decomposition, remaining weight of oak and pine leaf litter was 45.5% and 58.1%, respectively. Initial C/N ratio of oak and pine leaf litter was 53.4 and 153.0, respectively. Carbon % of initial oak and pine leaf litter was similar with each other; however, nitrogen content of initial oak leaf litter (0.85%) was greater than that of initial pine leaf litter (0.33%). N and P concentration in both decomposing leaf litter increased significantly during decomposition. There was no net N and P mineralization period in decomposing pine leaf litter. K, Ca and Mg concentration in both decomposing leaf litter showed different pattern with those of N and P. After 30 months decomposition, remaining nutrients in oak and pine leaf litter were 97.7 and 216.2% for N, 123.2 and 216.5% for P, 39.3 and 44.8% for K, 47.9 and 40.6% for Ca, 30.7 and 51.2% for Mg, respectively.

Cr(OH)₃(s) Oxidation Induced by Surface Catalyzed Mn(II) Oxidation

Namgung, Seonyi,Kwon, Man Jae,Qafoku, Nikolla P.,Lee, Giehyeon American Chemical Society 2014 Environmental science & technology Vol.48 No.18

<P>We examined the feasibility of Cr(OH)<SUB>3</SUB>(s) oxidation mediated by surface catalyzed Mn(II) oxidation under common groundwater pH conditions as a potential pathway of natural Cr(VI) contaminations. Dissolved Mn(II) (50 μM) was reacted with or without synthesized Cr(OH)<SUB>3</SUB>(s) (1.0 g/L) at pH 7.0–9.0 under oxic or anoxic conditions. Homogeneous Mn(II) oxidation by dissolved O<SUB>2</SUB> was not observed at pH ≤ 8.0 for 50 days. At pH 9.0, by contrast, dissolved Mn(II) was completely removed within 8 days and precipitated as hausmannite. When Cr(OH)<SUB>3</SUB>(s) was present, this solid was oxidized and released substantial amounts of Cr(VI) as dissolved Mn(II) was added into the suspension at pH ≥ 8.0 under oxic conditions. Production of Cr(VI) was attributed to Cr(OH)<SUB>3</SUB>(s) oxidation by a newly formed Mn oxide via Mn(II) oxidation catalyzed on Cr(OH)<SUB>3</SUB>(s) surface. XANES results indicated that this surface-catalyzed Mn(II) oxidation produced a mixed valence Mn(III/IV) solid phase. Our results suggest that toxic Cr(VI) can be naturally produced via Cr(OH)<SUB>3</SUB>(s) oxidation coupled with the oxidation of dissolved Mn(II). In addition, this study evokes the potential environmental hazard of sparingly soluble Cr(OH)<SUB>3</SUB>(s), which has been considered the most common and a stable remediation product of Cr(VI) contamination.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/esthag/2014/esthag.2014.48.issue-18/es503018u/production/images/medium/es-2014-03018u_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/es503018u'>ACS Electronic Supporting Info</A></P>

Formation of diverse Mn oxides: a review of bio/geochemical processes of Mn oxidation

Namgung, Seonyi,Chon, Chul-Min,Lee, Giehyeon Springer-Verlag 2018 Geosciences Journal Vol.22 No.2

Synthesis of Prussian blue-embedded porous polymer for detection and removal of Cs ions

Namgung, Ho,Gwon, Young Jin,Kim, Jongho,Jang, Geunseok,Pepper, Sarah E.,Ogden, Mark D.,Whittle, Karl R.,Harwood, Laurence M.,Lee, Taek Seung Elsevier 2018 Polymer Vol.158 No.-

<P><B>Abstract</B></P> <P>A Prussian blue (PB)-embedded coordination polymer (COP) was prepared by simple incorporation of PB into a COP composed of 1,1,2,2-tetrakis(4-carboxyphenyl)ethane and the Zn ion during the synthesis of COP. The PB-COP was prepared as micro-sized particles with green emission (490 nm) from the strongly fluorescent tetraphenylethene group in the solid state through aggregation-induced emission. The PB-COP showed particle shape with sizes ranging from 1 to 6 μm. As the PB in PB-COP efficiently adsorbed Cs ions, the microstructure of PB-COP was degraded to smaller particles, along with a concomitant decrease in the green fluorescence of the PB-COP. Such a decrease in the green emission of PB-COP was used as a signal for the presence of Cs ions, in which the limit of detection for Cs ions was found to be 73.8 ppb. The hybridized material of the PB-COP can be used as both an efficient adsorbent and a sensor for Cs ions, achieving simultaneous removal and detection.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A hybrid material was prepared with coordination polymer (COP) and Prussian blue (PB). </LI> <LI> COP was prepared by ionic interaction between COOH of organic molecules and Zn ions. </LI> <LI> The hybrid materials could remove efficiently Cs ions via adsorption on PB. </LI> <LI> The fluorescence of COP in hybrid materials also decreased upon exposure to Cs ions. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Stretchable hydrogen sensors employing palladium nanosheets transferred onto an elastomeric substrate

Namgung, Gitae,Ta, Qui Thanh Hoai,Noh, Jin-Seo Elsevier 2018 Chemical physics letters Vol.703 No.-

<P><B>Abstract</B></P> <P>Stretchable hydrogen sensors were fabricated from Pd nanosheets that were transferred onto a PDMS substrate. To prepare the Pd nanosheets, a Pd thin film on PDMS was first biaxially stretched and then PDMS substrate was etched off. The size of Pd nanosheets decreased as the applied strain increased and the film thickness decreased. A transfer technique was utilized to implement the stretchable hydrogen sensors. The stretchable sensors exhibited negative response behaviors upon the exposure to hydrogen gas. Interestingly, the sensors worked even under large strains up to 30%, demonstrating a potential as a high-strain-tolerable hydrogen sensor for the first time.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Palladium (Pd) nanosheets were prepared by a combination of biaxial stretching and PDMS delamination. </LI> <LI> The size of Pd nanosheets could be controlled by adjusting the applied strain and film thickness. </LI> <LI> Stretchable hydrogen gas sensors were fabricated using the Pd nanosheets. </LI> <LI> The stretchable sensors responded to hydrogen gas even under a 30% strain. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Pd nanosheets were prepared by biaxially stretching a Pd film on PDMS and subsequently delaminating the PDMS. It was demonstrated that stretchable hydrogen sensors fabricated from the Pd nanosheets could respond to hydrogen gas even under large strains up to 30%.</P> <P>[DISPLAY OMISSION]</P>