• Economic and Environmental Geology
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• v.46 no.3
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• pp.221-234
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• 2013

Laboratory experiments for the reaction with supercritical $CO_2$ under the $CO_2$ sequestration condition were performed to investigate the mineralogical and geochemical weathering process of the sandstones and mudstones in the Pohang basin. To simulate the supercritical $CO_2$-rock-groundwater reaction, rock samples used in the experiment were pulverized and the high pressurized cell (200 ml of capacity) was filled with 100 ml of groundwater and 30 g of powdered rock samples. The void space of the high pressurized cell was saturated with the supercritical $CO_2$ and maintained at 100 bar and $50^{\circ}C$ for 60 days. The changes of mineralogical and geochemical properties of rocks were measured by using XRD (X-Ray Diffractometer) and BET (Brunauer-Emmett-Teller). Concentrations of dissolved cations in groundwater were also measured for 60 days of the supercritical $CO_2$-rock-groundwater reaction. Results of XRD analyses indicated that the proportion of plagioclase and K-feldspar in the sandstone decreased and the proportion of illite, pyrite and smectite increased during the reaction. In the case of mudstone, the proportion of illite and kaolinite and cabonate-fluorapatite increased during the reaction. Concentration of $Ca^{2+}$ and $Na^+$ dissolved in groundwater increased during the reaction, suggesting that calcite and feldspars of the sandstone and mudstone would be significantly dissolved when it contacts with supercritical $CO_2$ and groundwater at $CO_2$ sequestration sites in Pohang basin. The average specific surface area of sandstone and mudstone using BET analysis increased from $27.3m^2/g$ and $19.6m^2/g$ to $28.6m^2/g$ and $26.6m^2/g$, respectively, and the average size of micro scale void spaces for the sandstone and mudstone decreased over 60 days reaction, resulting in the increase of micro pore spaces of rocks by the dissolution. Results suggested that the injection of supercritical $CO_2$ in Pohang basin would affect the physical property change of rocks and also $CO_2$ storage capacity in Pohang basin.

• Korean Journal of Microbiology
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• v.47 no.2
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• pp.117-123
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• 2011

The purpose of this study was to evaluate and compare different elution and concentration methods for optimization of human rotavirus (HRV) detection method using real-time RT-PCR and cell culture techniques. The leafy vegetable samples (lettuce, Chinese cabbage) were artificially inoculated with HRV. Viruses were extracted from the vegetables by two different elution buffers, buffer A (100 mM Tris-HCl, 50 mM glycine, 3% beef extract, pH 9.5) and buffer B (250 mM Threonine, 300 mM NaCl, pH 9.5), and the extracted viruses were concentrated by filtration and PEG precipitation sequentially. To determine infectivity of the viruses, the viruses recovered from the samples were infected to the MA-104 cells, and integrated cell culture real-time RT-PCR was performed at 1, 48, 72, 96, 120, 144, 168 h post-infection (p.i.). The elution buffer A was more efficient in extracting the virus from the produce samples tested than the buffer B, 29.54% and 18.32% of recoveries, respectively. The sensitivity of real-time RT-PCR method was markedly improved when the virus was concentrated by the filtration method. When the viruses were eluted and concentrated by buffer A and filtration, respectively, the average recovery rate was approximately 51.89%. When the viruses recovered from samples were infected to MA-104 cell, infectious HRV was detected within 48 h p.i. by ICC/real-time RT-PCR, whereas cytopathic effects were not observed until 72 h p.i. The optimized detection method evaluated in this study could be useful for rapid and reliable detection of HRV in fresh produce products and applied for detection of other food-borne viruses.

• Journal of Korean Society on Water Environment
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• v.22 no.6
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• pp.1101-1106
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• 2006

Many BNR (Biological Nutrient Removal) plants have experienced a bulking problem, mainly due to the growth of filamentous organisms, particularly during the winter months. This study investigated the problem of bulking due to the growth of M. parvicella both at a full-scale municipal wastewater treatment plant and a pilot scale plant located in the C city. The full-scale facility was operated at a flow rate of $51,000m^3/d$, an F/M (Food-to-Microorganism) ratio of 0.12 kgBOD/kgMLVSS/d and an SRT (Solids Retention Time) higher than 25 days, respectively. This plant experienced bulking and foaming problems at low temperatures below $15^{\circ}C$ since it was retrofitted with the BNR system in 2003. The pilot plant employed had an identical process configuration as the full scale one and used the same wastewater source. It was operated at a flow rate of $3.8m^3/d$, temperatures between 10 to $25^{\circ}C$ and SRTs between 10 and 25 days. At full scale, the M. parvicella growth and SVI (Sludge Volume Index) patterns were studied in conjunction with temperature variations. At pilot scale, DO and SRT variations were also explored, in addition to the filamentous bacteria growth and SVI patterns. During the full-scale investigation, over a 3 year period, it was noted that the SVI was maintained within acceptable operational values (i.e. under 160) during the summer months. Moreover settling in the secondary clarifiers was good and was not affected by the presence of M. parvicella. In contrast, at low mean temperatures during winter, the SVI increased to over 300. Overall, as the temperature decreased, the predominance of M. parvicella became apparent. According to this study, M. parvicella growth could be controlled and SVI could drop under 160 by a change in operational conditions which involved an increase in DO concentration between 2 and 4 mg/L and a decrease in SRT to less than 20 days.

• Journal of Korean Society of Disaster and Security
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• v.12 no.4
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• pp.1-13
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• 2019

Recently, as the occurrence frequency of sudden floods due to climate change increased, it is necessary to install the facilities that can cope with the initial stormwater. Most researches have been conducted on the design of facilities applying the Low Impact Development (LID) and the reduction effect on rainfall runoff to examine with 1D or 2D numerical models. However, the studies on the examination about flow characteristics and stability of pipe network systems were relatively insufficient in the literature. In this study, the stability of the pipe network system in rainwater storage tank was examined by using 3D numerical model, FLOW-3D. The changes of velocity and dynamic pressure were examined according to the number of rainwater storage tank and compared with the design criteria to derive the optimal design plan for a rainwater storage tank. As a results of numerical simulation with the design values in the previous study, it was confirmed that the velocity became increased as the number of rainwater storage tank increased. And magnitude of the velocity in pipes was formed within the design criteria. However, the velocity in the additional rainwater storage pipe was about 3.44 m/s exceeding the allowable range of the design criteria, when three or more additional rainwater storage tanks were installed. In the case of turbulence intensity and bottom shear stress, the bottom shear stress was larger than the critical shear stress as the additional rainwater storage was increased. So, the deposition of sediment was unlikely to occur, but it should be considered that the floc was formed by the reduction of the turbulence intensity. In addition, the dynamic pressure was also satisfied with the design criteria when the results were compared with the allowable internal pressure of the pipes generally used in the design of rainwater storage tank. Based on these results, it was suitable to install up to two additional rainwater storage tanks because the drainage becomes well when increasing of the number of storage tank and the velocity in the pipe becomes faster to be vulnerable to damage the pipe. However, this study has a assumption about the specifications of the rainwater storage tanks and the inflow of stormwater and has a limitation such that deriving the suitable rainwater storage tank design by simply adding the storage tank. Therefore, the various storage tank types and stormwater inflow scenarios will be asked to derive more efficient design plans in the future.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.3
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• pp.151-162
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• 1977

Distribution of marine algae is diverse in Korea and the resource of edible algae is abundant marking 239,037 tons of yearly production in 1976. They have been known as a protein source and used as a supplement in Korean diet. It is necessary to estimate the potentiality and properties of usable algal proteins especially as food resources and studies of extraction and separation of the proteins, therefore, are basically required for this purpose. In this study, the influence of various factors including the sample treatment, extraction time and temperature, sample us extraction solvent ratio and pH upon the extractability of the water soluble protein was determined. And the effect of precipitation treatment for isolation of the algal protein from the extracts was also tested. Nine species of algae, the major ones in consumption as food namely Porphyra suborbiculata, Undaria pinnatifida, Hizikia fusiforme, Sargassum fulvellu, Enteromorpha linza, Codium fragile, Sargassum kjellmanianum and Ulva pertusa were collected as fresh from Kijang, Yangsan Gun, in the vicinity of Busan city. The content of crude protein $(N\times6.25)$ of the algae ranged from $9.46\%\;to\;24.14\% showing the highest value in Porphyra suborbiculata and the minimum in Hizikia fusiforme. In the effort of maceration of blending methods on the extractability, immersion freezing in dry ice-methanol solution appeared most effective yielding 1.5 to 2.5 times extractability than that of the mortar grinding method. The effect of the ratio of sample vs solvent on extractability differed from species. It was enhanced at the ratio of 1:20 (w/v) in Ulva pertusa and Enteromorpha linza while the ratio was 1:30 (w/v) for Cedium fragile, Undaria pinnatifida, Hizikia fusiferme, Sargassum fulvellum and Porphyra suborbiculata and 1:40 for Sargassum kjellmanianum respectively. The effect of extraction time and temperature was revealed differently from species which might be caused by differences in the constitution of algal tissues resulting in that the extraction for 1 hour at $50^{\circ}C$ gave the maximum extractabilily in Ulva pertusa and Enteromorpha linza, 2 hours in Porphyra suborbiculata, Hikikia fusiforme, Undaria pinnatifida, Sargassum kjellmanianum and 3 hours in Codium fragile. And the extractability was higher at $50^{\circ}C$ to $60^{\circ}C$ for the most of the tested samples except Hizikia fusiforme. The optimum pH for the extraction was 9 to 12. The recovery of extractable nitrogen to the total nitrogen was $63\%$ in average with the first extracts and $8.6\%$ with the second extracts respectively. Both extracts were prepared by 2 hour extraction at $50{\pm}1^{\circ}C$ with dry ice-methanol frozen and seasand macerated materials. And these conditions assumed to be an optimum for the extraction of water soluble algal proteins since the nitrogen content after the first extraction covered $90\%$ of the total water extractable nitrogen. In the precipitation of the extracted proteins, Barnstein method and methanol treatment seemed to be more efficient than other precipitation methods.

• Journal of Life Science
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• v.29 no.8
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• pp.854-860
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• 2019

This study investigated the optimum pH conditions for efficient extraction of protein from defatted Tenebrio molitor (TM) larvae. We examined the anti-inflammatory effect of protein derived from defatted TM larvae obtained by an alkaline extraction method. Six extraction pH values (7, 8, 9, 10, 11, and 12) and three precipitation pH values (2, 4, and 6) were used. The protein content, browning degree, and recovery yield of the protein obtained under each pH condition were determined. For efficient extraction of protein from defatted TM larvae, a combination of an extraction pH of 9 and precipitation pH of 4 resulted in a 32.4% recovery yield based on the extraction value and degree of browning. To determine whether the protein ameliorated inflammation by inhibition of macrophage activation by lipopolysaccharides (LPS), we measured nitric oxide (NO), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) expression in LPS-stimulated raw 264.7 macrophage cells. The protein markedly inhibited the production of NO without cytotoxicity and reduced the expression level of COX-2 and iNOS protein through the regulation of mitogen-activated protein kinases (MAPKs) and nuclear factor kappa B ($NF-{\kappa}B$) signaling. These results suggested that protein derived from TM larvae could have potential applications in anti-inflammatory therapeutic agents and protein supplements.

• Analytical Science and Technology
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• v.18 no.5
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• pp.396-402
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• 2005

We try to look for optimum conditions of pre-reductants like L-Cysteine, KI and $FeSO_4$ when analyzing inorganic arsenic by using hydride generation-atomic absorption spectrometry, and run a comparative study of effect in the analysis of them. Also, we separated and analyzed only inorganic arsenic by using $H_2SO_4$-trap to eliminate organic arsenic which are MMA(monomethylarsonate) and DMA(dimethylarsinate). Under the conditions of mixture acid of 1.8 M HCl and 0.08 M $HNO_3$, arsenic standard solution of 20 ppb have more higher absorbance than without adding acid. In case of L-Cysteine, As(V) completely reduces into As(III) when 0.5 g of L-Cysteine is reacted more than 30 mins. in weak acid condition of approximately 0.07 M $HNO_3$ or HCl. In the event of KI, As(V) completely reduces into As(III) when 3 g of KI is reacted more than 1hour in acid condition of 0.8 M $HNO_3$. On the occasion of $FeSO_4$, the inside of tube is blocked by precipitation by mixture reaction of $NaBH_4$ and $Fe^{2+}$, therefore, comparing to other pre-reductants, reproducibility of efficiency of reducing As(V) to As(III) is low. To evaluate the accuracy of the analytical results, we use NIST SRM 1643C Trace Elements in Water ($82.1{\pm}1.2ng/mL$). The results are satisfactory.

• Applied Chemistry for Engineering
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• v.26 no.3
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• pp.356-361
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• 2015

$Cd_{0.5}Zn_{0.5}S/ZnO$ composite photocatalysts were synthesized using the precipitation method and characterized by XRD, UV-vis DRS, PL and FE-SEM. Photocatalytic activities of the materials were evaluated by measuring the degradation of rhodamine B under visible light irradiation. Contrary to ZnO, $Cd_{0.5}Zn_{0.5}S/ZnO$ materials absorb visible light as well as UV and their absorption intensities in visible region increased with increasing the $Cd_{0.5}Zn_{0.5}S$ amount. The increment in the $Cd_{0.5}Zn_{0.5}S$ content in $Cd_{0.5}Zn_{0.5}S/ZnO$ also leads to reducing the particle size and consequently increasing the specific surface area. $Cd_{0.5}Zn_{0.5}S/ZnO$ materials with the larger $Cd_{0.5}Zn_{0.5}S$ content showed the higher activity in the photocatalytic degradation of rhodamine B under visible light irradiation. Therefore, the heterojunction effect between $Cd_{0.5}Zn_{0.5}S$ and ZnO as well as the adsorption capacity seems to give important contributions to the photocatalytic activity of the $Cd_{0.5}Zn_{0.5}S/ZnO$.

• Journal of the Korean GEO-environmental Society
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• v.14 no.8
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• pp.11-21
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• 2013

In-situ test to find the change of $Fe^{2+}$ and $Mn^{2+}$ concentrations and ion contents in groundwater was conducted during two pumping tests at the riverbank filtration site, where is the riverine area of the Nakdong River in Changnyeong-Gun. Groundwater was sampled at one pumping well and 10 monitoring wells during a 5 steps drawdown pumping test with the rates from $500m^3/day$ to $900m^3/day$ and a constant pumping test with $800m^3/day$. The change in ion concentration of groundwater was more remarkable during a step drawdown pumping test than a constant pumping test. Especially, the decrease in $Fe^{2+}$ and $Mn^{2+}$ concentrations was distinct in a step drawdown pumping test and it happens predominantly along the direction that the radius of pumping influence was small due to a good aquifer connectivity to a pumping position. The precipitation and the oxidation of iron and manganese were caused by an air inflow and a disturbance in groundwater flow due to an abrupt change in pumping rate. The pumping rate and spatial distribution of an aquifer around a pumping well need to be considered as an important factor for the development of in-situ iron and manganese treatment technology.

• Journal of Life Science
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• v.15 no.5 s.72
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• pp.696-702
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• 2005

Ozonation is a disinfection technique of harmful mi-crobes commonly used in the treatment of drinking water. And Biological Activated Carbon (BAC) treatment also provides numerous benefits for drinking water utilities, including removal of micro- pollutants, improved treatment processes. The multiful-stage ozonation and BAC play roles as effective methods for removing several materials in raw water. Water quality variation in Nak dong river and the removal efficiency of viruses by ozonation-BAC process were investigated on pilot scale. During the period of survey, most of water quality parameters including $NH_{4}^{+}-N$ were highly improved after passing through the BAC. The removal efficiency of poliovirus type III in water treatment process using pilot-plant,$ 99.6\% $ of viruses were removed by pre-ozonation, sedimentation and sand filteration process, $ 100\% $ were removed after in BAC filteration step. In the removal survey of viruses by ozonation, ap-proximately $ 61.1\% $ or polioviruses were inactivated by ozone of 0.4 mg/l within 5 min. and $ 100\% $ were inactivated by ozone of 0.8 mg/l over 10 min.