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Papers by si DO

This paper presents an asynchronous distributed algorithm for solving the maximum flow problem wh... more This paper presents an asynchronous distributed algorithm for solving the maximum flow problem which is based on the preflow-push approach of Golberg-Tarjan. Each node in graph initially knows the capacities of outgoing and incoming adjacent arcs, the source nodes knows additionally the number of nodes in graph. Nodes execute the same algorithm, and exchange messages with neighbors until the maximum flow is established. The algorithm is applicable in cases of multiple sources and/or targets. We give also here some ideas to adjust our algorithm to dynamic changes of arc capacities. For a graph of n nodes and m arcs, our algorithm takes O(n 2 m) message complexity and O(n 2) time complexity. 1

— The objective of this study was to investigate the effects of inorganic ions on persulfate (PS)... more — The objective of this study was to investigate the effects of inorganic ions on persulfate (PS) and peroxymonosulfate (PMS) oxidation to degrade trichloroethylene (TCE) in groundwater. First, the groundwater samples, which was taken from Wonju, Korea, were analyzed, and the highest concentration of target ions (Mg 2+, Ca 2+, Fe 2+, Mn 2+, Cl-, HCO 3) in those samples were used for the batch experiment. Based on batch test, all of target ions did not neither increase nor decrease the reactivity of both PS and PMS. Because of the fluctuation of groundwater compositions, it could be worthwhile to evaluate which ions increase or decrease the reactivity of oxidants. Therefore, a batch system with an excess of target ion was tested. The results showed that ferrous ion increased the reactivity of both PS and PMS. However, chloride ion increased the reactivity of PMS, but it inhibited the reactivity of PS. Moreover, residual concentration of PMS and PS were remained approximately 97~98%, ...

The International Journal of Plant, Animal and Environmental Sciences, 2012

Human bone marrow derived mesenchymal stem cells (BMMSCs), a source of important autologous stem ... more Human bone marrow derived mesenchymal stem cells (BMMSCs), a source of important autologous stem cells without ethical debate, have been used in both experimental and clinical treatment. Therefore, this research aims to isolate, culture and cryopreserve BMMSCs. Mesenchymal stem cells (MSCs) were preserved in each cryovial by slow freezing – rapid thawing method. Post-cryopreserved MSCs was analyzed the viability and the stemness by their expression of some specific markers, differentiation potential and proliferation ability. The results of this research showed it is easy to isolate the BMMSCs by culturing the mononuclear cells derived from human bone marrow in DMEM/F12 plus 15% FBS, 10 ng/ml FGF and 1% antibiotic–mycotic; the viability rates of thawed MSCs were 72.95+/-6.14%. Cryopreserved MSCs maintained the stemness after 1 year storage in nitrogen liquid. They expressed CD13, CD44, CD90, CD166 markers and were negative for CD14, CD34, CD45 and HLA-DR markers in similar to fresh ...

Heavy metals in plating wastewater are considered as one of the must-treated contaminants and the... more Heavy metals in plating wastewater are considered as one of the must-treated contaminants and the adsorption using low-cost materials has been studied as the cost-effective alternative. Based on the parameter (Q o) calculated from Langmuir isotherm, Cu (1.68 mg/g) had a higher affinity to waste-reclaimed adsorbent than Zn (0.06 mg/g). The removal efficiency of metal ions (i.e. Cu and Zn) at various pHs was tested, and it was revealed that the removal of metal ions was interpreted by both adsorption and precipitation. The optimum pH for the removal (i.e. both adsorption and precipitation) of both Cu and Zn was 9, and the highest adsorption of Cu and Zn was observed at the pH of 5 for the artificial solution and at the pH of 7 for plating wastewater. Moreover, unlike the adsorption of Cu and Zn in the artificial solution, Cu and Zn in plating wastewater was adsorbed even at the pH of 12. To examine adsorption phenomenon, the relationship of the surface charge of adsorbent and the pH o...

The Coronavirus disease-2019 (COVID-19) pandemic caused by the Severe Acute Respiratory Syndrome ... more The Coronavirus disease-2019 (COVID-19) pandemic caused by the Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2), has become a dire global health concern. The development of vaccines with high immunogenicity and safety is crucial for control of the global COVID-19 pandemic and prevention of further illness and fatalities. Here, we report development of SARS-CoV-2 vaccine candidate, Nanocovax, based on recombinant protein production of the extracellular (soluble) portion of the S protein of SARS-CoV-2. The results showed that Nanocovax induced high levels of S protein-specific IgG, as well neutralizing antibody in three animal models including Balb/C mice, Syrian hamsters, and non-human primate (Macaca leonina). In addition, the viral challenge study using the hamster model showed that Nanocovax protected the upper respiratory tract from SARS-CoV-2 infection. No adverse effects were induced by Nanocovax in swiss mice (Musmusculus var. Albino), Rats (Rattus norvegicus), and...

The Science of the total environment, Jan 15, 2018

A kinetic model for the competitions was applied to understand the reductive dechlorination of te... more A kinetic model for the competitions was applied to understand the reductive dechlorination of tertiary DNAPL mixtures containing PCE, TCE, and 1,1,1-TCA. The model assumed that the mass transfer rates were sufficiently rapid that the target compounds in the solution and the DNAPL mixture were in phase equilibrium. Dechlorination was achieved using either a mixture of Fe(II), Fe(III), and Ca(OH) (Fe(II/III)-L) or a mixture of Fe(II) and Portland cement (Fe(II)-C). PCE in the DNAPL mixtures was gradually reduced and it was reduced more rapidly using Fe(II)-C than Fe(II/III)-L. A constant total TCE concentration in the DNAPL mixtures was observed, which implied that the rate of loss of TCE by dechlorination and possibly other processes was equal to the rate of production of TCE by PCE dechlorination. On the other hand, 1,1,1-TCA in the DNAPL mixtures was removed rapidly and its degradation rate by Fe(II/III)-L was faster than by Fe(II)-C. The coefficients in the kinetic model (k, K) w...

Journal of the Korean Society of Water and Wastewater

First of all, Fe or/and Mn immobilized granular activated carbons (Fe-GAC, Mn-GAC, (Fe, Mn)-GAC) ... more First of all, Fe or/and Mn immobilized granular activated carbons (Fe-GAC, Mn-GAC, (Fe, Mn)-GAC) were synthesized and tested to remove arsenate (As(V)). The results in batch test indicated that Fe-GAC removed As(V) effectively, even though the surface area of Fe-GAC was reduced largely. Moreover, adsorption isotherm test indicated that the experimental data fit well with Langmuir model and the maximum adsorption capacity (q max) of Fe-GAC for As(V) was 3.49 mg g-1 , which was higher than GAC (2.24 mg g-1). In column test, the simulated water, which consisted of As(V), Fe(III), Mn(II) and Ca(II) in tap water, was used. Fe-GAC column with 1 hr of pre-washing time treated As(V) effectively while GAC column removed Fe(III) better than Fe-GAC column. Moreover, the increasing pre-washing time from 1 to 9 hour in Fe-GAC column enhanced Fe(III) removal with little negative impact of As(V) removal. Mostly, the column filled with Fe-GAC and GAC (i.e. the mass ratio of Fe-GAC:GAC = 2:8) showed the higher treatability of both As(V) and Fe(III), even it operated with 1 hr pre-washing time.

Journal of the Korean Society of Water and Wastewater

The characteristics of filter/adsorber granular activated carbon (F/A GAC) were investigated by m... more The characteristics of filter/adsorber granular activated carbon (F/A GAC) were investigated by measuring various parameters, which include surface area, pore volume, abrasion number, floater, and water-soluble ash. The correlation between parameters was also evaluated. Moreover, rapid small-scale column test (RSSCT) was conducted for adsorption characteristics. Thirteen F/A GAC were tested, and the average values of abrasion number and water-soluble ash were 88.9 and 0.15%, respectively. F/A GAC with the larger external surface area and greater mesopore volume had the lower abrasion number, which indicated that it was worn out relatively easily. Water-soluble ash of coconut-based GAC (about 2.6%) was greater than that of coal-based GAC (less than 1%), and the pH of solution was increased with GAC, which had the higher water-soluble ash. On the other hand, floater of thirteen F/A GAC was divided as two groups, which one group had relatively higher floater (2.7~3.5%) and the other group had lower floater (approximately 0.5%). The results of RSSCT indicated that coconut-based GAC (i.e. relatively higher water-soluble ash) had less adsorption capacity. Moreover, adsorption capacity of coal-based GAC with larger surface area and greater mesopore volume was superior to others.

Journal of Environmental Chemical Engineering

Applicability of waste-reclaimed material (WR) to remove heavy metals (Cu 2+ and Zn 2+) in a plat... more Applicability of waste-reclaimed material (WR) to remove heavy metals (Cu 2+ and Zn 2+) in a plating wastewater was investigated. The mass (mg) of both Cu 2+ and Zn 2+ removed from solution was linearly increased when the initial concentrations increased from 10 to 100 mg/L. Experimental data was well predicted by both Langmuir and Freundlich models. In the Langmuir model, the values of R L (a dimensionless constant separation factor) indicated that adsorption of both Cu 2+ and Zn 2+ on WR were favorable (i.e. R L for Cu 2+ were 0.337-0.048 and R L for Zn 2+ were 0.775-0.256). Kinetically, adsorption of both Cu 2+ and Zn 2+ was predicted by pseudo-second order model. The highest q e of Cu 2+ and Zn 2+ were 1.6 Â 10 À1 and 8.1 Â 10 À2 mg/g, respectively. Moreover, the initial adsorption rate, h ðk 2 q 2 e Þ, was increased when initial concentrations of metal ions increased. The effect of pH on the removal of Cu 2+ and Zn 2+ revealed that some degrees of Cu 2+ and Zn 2+ were removed at the acidic condition. Moreover, all Cu 2+ was removed at pH 7, while Zn 2+ was completely removed at pH 9. Therefore, those results indicated that the surface characteristics, specifically both the surface charge and chemical compositions, could make WR a potential adsorbent. The use of WR showed that removal of metal ions satisfy the regulatory requirements (i.e. under 3.0 mg/L of Cu 2+ and 5.0 mg/L of Zn 2+) in Korea when experiments using large-scale reactors were conducted 20 times in plating wastewater.

Proceedings of the 2nd Annual International Conference on Sustainable Energy and Environmental Sciences (SEES 2013)

The applicability of soil washing/flushing to treat a contaminated soil with cadmium (Cd) and cop... more The applicability of soil washing/flushing to treat a contaminated soil with cadmium (Cd) and copper (Cu) using a mixture of organic/inorganic extractant was evaluated in laboratory-scale batch and column tests. Citric acid was the effective extractant to remove Cd and Cu from the soil among various organic acids except EDTA. Carbonic acid was chosen as inorganic extractant which was not only low toxicity to environment, but also increasing soil permeability. Moreover, the optimum ratio of organic and inorganic extractant to remove Cd and Cu was 10 : 1, and this ratio of organic and inorganic extractant achieved removal efficiencies of Cd (46%) and Cu (39%), respectively. The increasing flow rate of extractant could explain the phenomena of soil packing when carbonic acid was used with organic extractant (i.e. EDTA and citric acid). Therefore, a mixture of organic extractant with inorganic extractant, especially carbonic acid, could resolve a problem of soil packing when this extrac...

Heterogeneous Fenton system consisting of magnetite nano particle (MNP) catalyst has been develop... more Heterogeneous Fenton system consisting of magnetite nano particle (MNP) catalyst has been developed for the oxidation of nitrobenzene by hydrogen peroxide (H 2 O 2) in aqueous phase. Nitrobenzene was used as probe compound for detecting hydroxyl radical (. OH). The goals of this study were (1) to observe generation of hydroxyl radical in MNP/H 2 O 2 system using probe compound (nitrobenzene) and (2) compare with commercial magnetite to confirm its activity according to surface area. MNP was characterized by various techniques such as X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectra (XPS), and Brunauer-Emmett-Teller (BET). Degradation of nitrobenzene using MNP/H 2 O 2 system could be affected by MNP mass, and concentration of H 2 O 2. When effects of MNP mass and concentration of H 2 O 2 were tested, 2.4 g of MNP mass and 1% (294 mM) of H 2 O 2 were the optimum concentrations for the degradation of nitrobenzene at pH 3. Addition of H 2 O 2 from 0.25% (73.5 mM)-1% (294 mM) at 2.4 g of MNP, increased the first-order rate constants for the nitrobenzene degradation (0.035 to 0.101 h-1). The result of different pH value showed that pH 3 was optimum value for Fenton-like degradation of nitrobenzene. Commercial magnetite (<5um) was also tested to compare with MNP. Removal efficiency of nitrobenzene using MNP/H 2 O 2 system (51%) was greater than using commercial magnetite/H 2 O 2 system (8%).

Environmental technology, 2015

This study was conducted to investigate the inhibited influences on and solution to the degradati... more This study was conducted to investigate the inhibited influences on and solution to the degradation of four types of dense non-aqueous phase liquids (DNAPLs) (i.e. perchloroethylene [PCE], trichloroethylene [TCE], chloroform [CF], and carbon tetrachloride [CT]) all at the same instance in groundwater (GW). Degradations of DNAPLs in de-ionized water (DW) and GW were carried out by applying an ultraviolet radiation-activated persulphate (UV/PS) system. PCE and TCE were degraded by over 90% and CT was only degraded by 25% in both DW and GW. However, CF was degraded by over 90% in DW, while it was only degraded by 50% in GW. First of all, degradations with an inorganic anion (either Cl(-) or [Formula: see text]) indicated that the lower degradation of CF in GW was caused by the existence of the chloride ion. Moreover, the low CF degradation in GW was overcome by the additional injection of a base solution (sodium hydroxide [NaOH]) into the UV/PS system. The results showed that PCE, TCE,...

Biological research, Jan 15, 2014

Vascular endothelial growth factor (VEGF) is involved in the growth of new blood vessels that fee... more Vascular endothelial growth factor (VEGF) is involved in the growth of new blood vessels that feed tumors and kinesin spindle protein (KSP) plays a critical role in mitosis involving in cell proliferation. Simultaneous silencing of VEGF and KSP, an attractive and viable approach in cancer, leads on restricting cancer progression. The purpose of this study is to examine the therapeutic potential of dual gene targeted siRNA cocktail on human hepatocellular carcinoma Hep3B cells. The predesigned siRNAs could inhibit VEGF and KSP at mRNA level. siRNA cocktail showed a further downregulation on KSP mRNA and protein levels compared to KSP-siRNA or VEGF-siRNA, but not on VEGF expression. It also exhibited greater suppression on cell proliferation as well as cell migration or invasion capabilities and induction of apoptosis in Hep3B cells than single siRNA simultaneously. This could be explained by the significant downregulation of Cyclin D1, Bcl-2 and Survivin. However, no sigificant diffe...

Iranian biomedical journal, 2015

Kinesin spindle protein (KSP) plays a critical role in mitosis. Inhibition of KSP function leads ... more Kinesin spindle protein (KSP) plays a critical role in mitosis. Inhibition of KSP function leads to cell cycle arrest at mitosis and ultimately to cell death. The aim of this study was to suppress KSP expression by specific small-interfering RNA (siRNA) in Hep3B cells and evaluate its anti-tumor activity. Three siRNA targeting KSP (KSP-siRNA #1-3) and one mismatched-siRNA (Cont-siRNA) were transfected into cells. Subsequently, KSP mRNA and protein levels, cell proliferation, and apoptosis were examined in both Hep3B cells and THLE-3 cells. In addition, the chemosensitivity of KSP-siRNA-treated Hep3B cells with doxorubicin was also investigated using cell proliferation and clonogenic survival assays. The expression of endogenous KSP at both mRNA and protein levels in Hep3B cells was higher than in THLE-3 cells. In Hep3B cells, KSP-siRNA #2 showed a further downregulation of KSP as compared to KSP-siRNA #1 or KSP-siRNA #3. It also exhibited greater suppression of cell proliferation an...

Journal of hazardous materials, Jan 15, 2014

As(3+) removal by Ca-Mn-Fe3O4 composites, which contained various wt% of Ca, are investigated. Im... more As(3+) removal by Ca-Mn-Fe3O4 composites, which contained various wt% of Ca, are investigated. Immobilization of Ca (i.e. as crystalline forms including CaO2) and Mn (i.e. as an amorphous hydrous manganese oxide) on Fe3O4 were identified, and it was revealed that the co-immobilization of Ca and Mn (i.e. especially the wt% ratio of Ca:Mn:Fe=2:3:1) provided higher Ca wt% with greater surface area. The increasing Ca wt% (i.e. 6, 14, 17, and 19%) gradually increased the reactivity of H2O2 to oxidize As(3+) to As(5+). Moreover, it is suggested that superoxide anion produced from the catalytic decomposition of H2O2 reduces Mn(4+) to Mn(2+), which is further released into solution. On the other hand, As(3+) adsorption was decreased with the highest Ca wt% in Ca-Mn-Fe3O4. It was concluded that the increasing Ca wt% positively affected As(3+) oxidation but an excess Ca wt% negatively affected As(3+) adsorption. The higher As(3+) adsorption was observed when Ca wt% was 17 (i.e. the wt% ratios...

The International Journal of Plant, Animal and Environmental Sciences, 2012

The Science of the total environment, Jan 15, 2018

Journal of the Korean Society of Water and Wastewater

Journal of Environmental Chemical Engineering

Proceedings of the 2nd Annual International Conference on Sustainable Energy and Environmental Sciences (SEES 2013)

Environmental technology, 2015

Biological research, Jan 15, 2014

Iranian biomedical journal, 2015

Journal of hazardous materials, Jan 15, 2014