• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.10
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• pp.791-799
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• 2008

We investigate the flow characteristics around a series of rectangular bodies ($40^d{\times}80^w{\times}80^h$, $80^d{\times}80^w{\times}80^h$ and $160^d{\times}80^w{\times}80^h$) placed in a deep turbulent boundary layer. The study is aiming to understand the surface pressure distribution around the bodies such as the suction pressure in the leading edge, when the flow is normal, which is responsible for producing extreme suction pressures on the roof. The experiment includes wind tunnel work by using HWA (Hot-Wire anemometry) and pressure transducers. The experiments are carried out at three different Reynolds numbers, based on the velocity U at the body height h, of $2.4{\times}10^4$, $4.6{\times}10^4$ and $6.7{\times}10^4$, and large enough that the mean flow is effectively Reynolds number independent. The results include the measurements of the growth of the turbulent boundary layer in the wind tunnel and the surface pressure around the bodies.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.2
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• pp.156-159
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• 2001

The experiment was carried out to investigate the productivity of freshwater rotifer, Brachionus calyciflorus and marine rotifer, B. rotundiformis at various temperatures, initial inoculation and pH in a 5 L semi-continuous high density culture. Rotifers were fed by commercial condensed freshwater Chlorella. When pH was not controlled, average daily productions of freshwater and marine rotifers increased with temperature. The highest production, $44\times10^6$ rotifers, was achieved of B. calyciflorus at $32^{\circ}C$ and the possible production lasting period of B. calyciflorus was shorter than that of B. rotundiformis. Under the adjustment of pH at 7, the possible production lasting periods of B. calyciflorus and B. rotundiformis inoculated with 5,000 inds./mL were longer than those of rotifers inoculated with 10,000 inds./mL, and the daily production rate of the former was higher than that of the latter. The results from this study indicated that optimum density of the initial inoculation for the cultivation of B. calyciflorus and B. rotundiformis was 5,000 inds,/mL under the controlled conditions of pH 7 and at $32^{\circ}C$ in a semi-continuous high density culture, in terms of production rate and food cost aspects.

• Journal of Microbiology and Biotechnology
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• v.33 no.2
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• pp.211-218
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• 2023

A cryptic plasmid (pTH32) was characterized from Tetragenococcus halophilus 32, an isolate from jeotgal, Korean traditional fermented seafood. pTH32 is 3,198 bp in size with G+C content of 35.84%, and contains 4 open reading frames (ORFs). orf1 and orf2 are 456 bp and 273 bp in size, respectively, and their translation products showed 65.16% and 69.35% similarities with RepB family plasmid replication initiators, respectively, suggesting the rolling-circle replication (RCR) mode of pTH32. orf3 and orf4 encodes putative hypothetical protein of 186 and 76 amino acids, respectively. A novel Tetragenococcus-Escherichia coli shuttle vector, pMJ32E (7.3 kb, Em^r), was constructed by ligation of pTH32 with pBluescript II KS(+) and an erythromycin resistance gene (ErmC). pMJ32E successfully replicated in Enterococcus faecalis 29212 and T. halophilus 31 but not in other LAB species. A pepA gene, encoding aminopeptidase A (PepA) from T. halophilus CY54, was successfully expressed in T. halophilus 31 using pMJ32E. The transformant (TF) showed higher PepA activity (49.8 U/mg protein) than T. halophilus 31 cell (control). When T. halophilus 31 TF was subculturd in MRS broth without antibiotic at 48 h intervals, 53.8% of cells retained pMJ32E after 96 h, and only 2.4% of cells retained pMJ32E after 14 days, supporting the RCR mode of pTH32. pMJ32E could be useful for the genetic engineering of Tetragenococcus and Enterococcus species.

• Journal of IKEEE
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• v.25 no.1
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• pp.15-24
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• 2021

In this paper, 1700 V EPDT (Extended P+ shielding floating gate Double Trench) MOSFET structure, which has a smaller switching time and loss than CDT (Conventional Double Trench) MOSFET, is proposed. The proposed EPDT MOSFET structure extended the P+ shielding area of the source trench in the CDT MOSFET structure and divided the gate into N+ and floating P- polysilicon gate. By comparing the two structures through Sentaurus TCAD simulation, the on-resistance was almost unchanged, but Crss (Gate-Drain Capacitance) decreased by 32.54 % and 65.5 %, when 0 V and 7 V was applied to the gate respectively. Therefore, the switching time and loss were reduced by 45 %, 32.6 % respectively, which shows that switching performance was greatly improved.

• Journal of Korean Society of Forest Science
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• v.102 no.4
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• pp.571-577
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• 2013

This study was carried out to establish the construction guidelines of soil erosion control structures for a restoration of mountain stream with analysis of water quality around constructed soil erosion control structures in mountain streams. Water pH of the Uidong valleys in Bukhansan (Mt.) was similar between the constructed soil erosion control structures of lower stream areas [pH 6.53(6.25~6.82)] and the non-constructed areas of upper stream areas [pH 6.32(5.73~6.90)]. Mean concentration of dissolved oxygen was also similar between the constructed soil erosion control structures of lower steam areas [10.2 mg/L(9.9~10.4 mg/L)] and the non-constructed areas of upper stream areas [10.3 mg/L (9.6~10.6 mg/L)]. Mean electric conductivity was similar between the lower [$63.9{\mu}S/cm$ ($32.6{\sim}120.4{\mu}S/cm$)]a nd the upper stream areas [$62.2{\mu}S/cm$ ($40.3{\sim}89.5{\mu}S/cm$)]. Mean concentration of anions was also similar between the lower [15.94 mg/L (3.43~7.98 mg/L)] and the upper stream areas [14.51 mg/L (2.56~4.29 mg/L)]. Water pH of the Honggei valleys in Sancheong-gun was similar between the lower [pH 6.86(6.50~7.10)] and the upper stream areas [pH 6.89(6.61~7.12)]. Mean concentration of dissolved oxygen was also similar between the lower [11.9 mg/L(11.5~12.3 mg/L)] and the upper stream areas [12.2 mg/L (11.6~12.6 mg/L)]. Mean electric conductivity was similar between the lower [$633.4{\mu}S/cm$ ($31.6{\sim}34.6{\mu}S/cm$)] and the upper stream areas [$32.7{\mu}S/cm$ ($31.4{\sim}34.3{\mu}S/cm$)]. Mean concentration of anion was also similar to both stream areas [1.0 mg/L (0.1~2.2 mg/L)]. Water quality in the Uidong and the Honggei valleys was not significantly different between the constructed soil erosion control structures of lower stream areas and the non-constructed areas of upper stream areas. It will be needed to study the time-series analysis of water quality before and after the construction of soil erosion control structure the restoration of mountain streams because the water quality in mountain streams could be affected during the construction processes of structures.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.988-992
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• 2011

$CO_2$ adsorption on mineral sorbents has a potential to sequester $CO_2$. This study used a density functional theory (DFT) study of $CO_2$ adsorption on barium oxide (BaO) in the presence of $H_2O$ to determine the role of $H_2O$ on the $CO_2$ adsorption properties on the ($2{\times}2$; $11.05\;{\AA}{\times}11.05\;{\AA}$) BaO (100) surface because BaO shows a high reactivity for $CO_2$ adsorption and the gas mixture of power plants generally contains $CO_2$ and $H_2O$. We investigated the adsorption properties (e.g., adsorption energies and geometries) of a single $CO_2$ molecule, a single $H_2O$ molecule on the surface to achieve molecular structures and molecular reaction mechanisms. In order to evaluate the coordinative effect of $H_2O$ molecules, this study also carried out the adsorption of a pair of $H_2O$ molecules, which was strongly bounded to neighboring (-1.91 eV) oxygen sites and distant sites (-1.86 eV), and two molecules ($CO_2$ and $H_2O$), which were also firmly bounded to neighboring sites (-2.32 eV) and distant sites (-2.23 eV). The quantum mechanical calculations show that $H_2O$ molecule does not influence on the chemisorption of $CO_2$ on the BaO surface, producing a stable carbonate due to the strong interaction between the $CO_2$ molecule and the BaO surface, resulting from the high charge transfer (-0.76 e).

• Advances in environmental research
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• v.1 no.1
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• pp.1-14
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• 2012

We demonstrated that reductive degradation of 2,4,6-Trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (Royal Demolition Explosive, RDX) can be enhanced by bio-reduced iron-bearing soil minerals (IBSMs) using Shewanella putrefaciens CN32 (CN32). The degradation kinetic rate constant of TNT by bio-reduced magnetite was the highest (0.0039 $h^{-1}$), followed by green rust (0.0022 $h^{-1}$), goethite (0.0017 $h^{-1}$), lepidocrocite (0.0016 $h^{-1}$), and hematite (0.0006 $h^{-1}$). The highest rate constant was obtained by bio-reduced lepidocrocite (0.1811 $h^{-1}$) during RDX degradation, followed by magnetite (0.1700 $h^{-1}$), green rust (0.0757 $h^{-1}$), hematite (0.0495 $h^{-1}$), and goethite (0.0394 $h^{-1}$). Significant increase of Fe(II) was observed during the reductive degradation of TNT and RDX by bio-reduced IBSMs. X-ray diffraction and electron microscope analyses were conducted for identification of degradation mechanism of TNT and RDX in this study. 4-amino-dinitrotoluene were detected as products during TNT degradation, while Hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine, Hexahydro-1,3-dinitroso-5-nitro-1,3,5triazine, and Hexahydro-1,3,5-trinitroso-1,3,5-triazine were observed during RDX degradation.

• Journal of Sensor Science and Technology
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• v.32 no.2
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• pp.82-87
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• 2023

This study proposes a pH-dissolved-oxygen monitoring system using 8-HydroxyPyrene-1,3,6-trisulfonic acid Trisodium Salt (HPTS) and tris(4,7-diphenyl-1,10-phenanthroline)Ruthenium(II) chloride (Ru_dpp). Commercial water-quality sensors are electrochemical devices that require frequent calibration and cleaning, are subject to high maintenance costs, and have difficulties conducting measurements in real-time. The proposed pH-dissolved-oxygen monitoring system selects a thin-film sensing layer to measure the change in fluorescence intensity. This change in fluorescence intensity is based on reactions with hydrogen ions in an aqueous solution at a given pH and specific amount of dissolved oxygen. The change in fluorescence intensity is then measured using light-emitting diodes and photodiodes in response to HPTS and Ru_dpp. This method enables the development of a relatively small, inexpensive, and real-time measureable water-quality measurement system.

• ETRI Journal
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• v.32 no.2
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• pp.336-338
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• 2010

A macroblock-level deblocking method is proposed for H.264/AVC, in which blocking artifacts are effectively eliminated in the discrete cosine transform domain at the macroblock encoding stage. Experimental results show that the proposed algorithm outperforms conventional H.264 in terms of coding efficiency, and the bitrate saving is up to 5.7% without reconstruction quality loss.

• Korean Journal of Poultry Science
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• v.32 no.2
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• pp.135-141
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• 2005

Changes in serum estradiol, insulin-like growth factor-1, leuteinizing and testosterone levels, and leuteinizing hormone-stimulated testosterone production per testis in vitro from hatching to adulthood were studied in Korean native chickens of 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 21, 24, 28, 32, 44, 52 and 64 weeks (n=13 chickens per group) of age. The changes in the profiles of the levels in the incubation medium of luteinizing hormone-stimulated (100 ng/mL) testosterone secretion per testis in vitro, and the serum LH, testosterone, estradiol, and insulin-like growth factor-I were determined by radioimmunoassay. Serum estradiol levels were not significantly different at week 4 compared to that of 8, 12, 16, 21, 32, :md 44. Significant decreases were observed at weeks 52 and 64. Serum leuteinizing hormone concentrations were not significantly different from 1 week to 12 weeks, increased gradually up to 32 weeks of age, and declined significantly thereafter; the highest value was at 32 weeks, and the lowest value was detected at 2 weeks of age. Serum insulin-like growth factor-I concentrations increased significantly from 1 week to 16 weeks, remained low and unchanged with advancing age. Serum testosterone concentrations were not significantly different at week 1 compared weeks 2, 4, 6, and 8. Significant increases were observed from 10 weeks to 32 weeks of age. Values at weeks 24, 28 and 32 and at weeks 32, 44, 52, and 64 were not significantly different. The highest value was at weeks 28 and the lowest value was detected at weeks 1 week. LH-stimulated testosterone production per testis in vitro increased gradually with age from 1 to 32 weeks and decreased significantly from 44 weeks to 64 weeks of age.