• Journal of Radiation Protection and Research
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• v.24 no.2
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• pp.73-86
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• 1999

The ion-exchange method for the purification of primary coolant has been used broadly in PWR(pressurized water reactor)-type nuclear power plants due to its high decontamination efficiency, simple system, and easy operation. However, its non-selective removal of metal and non-radionuclides shortens its life, resulting in the generation of a large amount of waste ion-exchange resin. In this study, the feasibility of electrodeionization (EDI) was investigated for the purification of primary cooling water using synthetic solutions under various experimental conditions as an alternative method for the ion exchange. The results shows that as the feed flow-rate increased, the removal efficiency increased and the power consumption decreased. The removal rate was observed as a 1000 decontamination factor(DF) at a nearly constant level. For the synthetic solution of 3 ppm TDS (Total Dissolved Solid), the power consumption was 40.3 mWh/L at 2.0 L/min of feed flow rate. The higher removal rate of metal species and lower power consumption were obtained with greater resin volume per diluting compartment. However, the flow rate of the EDI process decreased with the elapsed time because of the hydrodynamic resistivity of resin itself and resin fouling by suspended solids. Thus, the ion-exchange resin was replaced by an ion-conducting spacer in order to overcome the drawback. The system equipped with the ion-conducting spacer resolved the problem of the decreasing flow rate but showed a lower efficiency in terms of the power consumption, the removal rate of metal species and current efficiency. In the repeated batch operation, it was found that the removal efficiency of metal species was stably maintained at DF 1000.

• The Korean Journal of Mycology
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• v.50 no.4
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• pp.331-341
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• 2022

This study was conducted to identify yeast species isolated from domestic pear blossom through gene sequencing and analysis of morphological characteristics, and to confirm specific yeast species inhibitory effects toward fire blight in immature apples, pears, and crab apple blossoms. Yeast morphological characteristics were consistent with the known characteristics of Aureobasidium pullulans. Nucleotide sequencing of the D1/D2 region of large-subunit (LSU) 26S ribosomal DNA and the internal transcribed spacer (ITS) region confirmed its identity as A. pullulans (MHAU2101). Inoculation of immature fruits with A. pullulans MHAU2101 before exposure to Erwinia amylovora prevented fire blight symptoms in apples and pears. A. pullulans MHAU2101 treated crab apple blossoms had a significantly lower flower infection rate than untreated blossoms, revealing 64% of the potency of streptomycin. The A. pullulans MHAU2101 treated group also displayed lower E. amylovora density in both pistil and hypanthium compared to the untreated group, especially in the hypanthium. This study confirms that A. pullulans MHAU2101 isolated from domestic pear blossom can effectively suppress the onset of fire blight.

• Nuclear Engineering and Technology
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• v.47 no.4
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• pp.416-423
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• 2015

It had been disputed how to apply wall drag to the dispersed phase in the framework of the conventional two-fluid model for two-phase flows. Recently, Kim et al. [1] introduced the volume-averaged momentum equation based on the equation of a solid/fluid particle motion. They showed theoretically that for dispersed two-phase flows, the overall two-phase pressure drop by wall friction must be apportioned to each phase, in proportion to each phase fraction. In this study, the validity of the proposed wall drag model is demonstrated though one-dimensional (1D) simulations. In addition, it is shown that the existing form loss model incorrectly predicts the motion of the dispersed phase. A new form loss model is proposed to overcome that problem. The newly proposed form loss model is tested in the region covering the lower plenum and the core in a nuclear power plant. As a result, it is shown that the new models can correctly predict the relative velocity of the dispersed phase to the surrounding fluid velocity in the core with spacer grids.

• Molecules and Cells
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• v.23 no.2
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• pp.220-227
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• 2007

The development of suitable genetic markers would be useful for defining species and delineating the species boundaries of morphologically indistinguishable sponges. In this study, genetic variation in the sequences of nuclear rDNA and the mitochondrial cytochrome c oxidase subunit 1 and 3 (CO1 and CO3) regions were compared in morphologically indistinguishable Korean Halichondriidae sponges in order to determine the most suitable species-specific molecular marker region. The maximal congeneric nucleotide divergences of Halichondriidae sponges in CO1 and CO3 are similar to those found among anthozoan cnidarians, but they are 2- to 8-fold lower than those found among genera of other triploblastic metazoans. Ribosomal internal transcribed spacer regions (ITS: ITS1 + ITS2) showed higher congeneric variation (17.28% in ITS1 and 10.29% in ITS2) than those of CO1 and CO3. Use of the guidelines for species thresholds suggested in the recent literature indicates that the mtDNA regions are not appropriate for use as species-specific DNA markers for the Halichondriidae sponges, whereas the rDNA ITS regions are suitable because ITS exhibits a low level of intraspecific variation and a relatively high level of interspecific variation. In addition, to test the reliability of the ITS regions for identifying Halichondriidae sponges by PCR, a species-specific multiplex PCR primer set was developed.

• Mycobiology
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• v.48 no.5
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• pp.341-350
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• 2020

Three fungal strains belonging to the class Sordariomycetes were isolated from soils collected from Gyeongsangbuk-do in Korea. They were identified as Cephalotrichum hinnuleum (UD CT 1-3-3 and KNU-19GWF1) and Thelonectria chlamydospora sp. nov. (UD ST 1-2-1). T. chlamydospora sp. nov. was morphologically identical to T. truncata, but its specific macroconidial dimensions, lower number of septations, and chlamydospore diameter render it distinct from the strains of the genus Thelonectria. The strains UD CT 1-3-3 and KNU-19GWF1 were developed flat, velvety to felty, and golden gray to brown-gray after 14 days of incubation at 25 ℃ on PDA. These strains were produced polyblastic conidiogenous cells and conidia were pale brown to brown, smooth, thin-walled, subglobose to ellipsoidal, arranged in chains, and the diameters of 6.7-9.0 × 3.7-5.1 ㎛. The strains were also confirmed by using the multi-locus genes using internal transcribed spacer (ITS) regions, partial large subunit (LSU), translation elongation factor 1α (TEF1-α), β-tubulin (TUB2), and actin (ACT) genes. This is the discovery of T. chlamydospora sp. nov. and Cephalotrichum hinnuleum, a new record from Korea.

• The Korean Journal of Mycology
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• v.49 no.4
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• pp.477-486
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• 2021

A survey of insect-associated fungi in Korea revealed a novel fungal strain isolated from the bean bug Riptortus clavatus (Heteroptera: Alydidae). Culturally and morphologically, the fungal strain designated KNUF-20-INY03, shares features with members of the genus Acaulium. Phylogenetic analyses based on the concatenated nucleotide sequences of the internal transcribed spacer regions (ITS) regions and partial sequences of the translation elongation factor 1-alpha (TEF1-α), and β-tubulin (β-TUB), and large subunit of the nuclear ribosomal RNA (LSU) genes showed that the isolate is part of a clade that includes other Acaulium species, but it occupies a distinct phylogenetic position. Based on the shape, size, and color of its conidia and conidiogenous cells, strain KNUF-20-INY03 is readily distinguishable from the closely related A. acremonium, A. albonigrescens, A. caviariformis, A. pannemaniae, and A. retardatum. The conidial length-to-width ratio (1.6) of the novel isolate is significantly lower than that of A. acremonium (1.9), A. albonigrescens (2.4), and A. pannemaniae (2.4), and KNUF-20-INY03 produces hyaline conidia and elliptical conidiogenous cells while A. caviariformis forms brown conidia and A. retardatum produces flask-shaped conidiogenous cells. Thus, both phylogenetic and morphological analyses indicate that this strain is a novel species in the genus Acaulium, and we propose the name Acaulium microspora sp. nov.

• Mycobiology
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• v.48 no.6
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• pp.495-500
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• 2020

Leaf spot on lemon balm is frequently observed in Korea, causing considerable damage to crops. In 2014 and 2015, the occurrence of leaf spot was observed in several production greenhouses at Suwon, Gongju, and Namwon in Korea. Symptoms on lower leaves initially developed as small, distinct, discolored lesions, which enlarged progressively turning into dark brown, angular spots surrounded by purplish-brown margins. Based on the morphological characteristics and sequence analysis of actin (ACT), translation elongation factor 1-alpha (EF-1α), internal transcribed spacer (ITS), 28S nrDNA (LSU), and RNA polymerase II second largest subunit (RPB2), the fungus associated with the lemon balm leaf spot was determined as Septoria melissae. To the best of our knowledge, this is the first report of lemon balm leaf spot caused by S. melissae in Asia as well as in Korea.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.2
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• pp.172-178
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• 2016

In this paper, we propose a sub-10 nm Ge/GaAs heterojunction-based tunneling field-effect transistor (TFET) with vertical band-to-band tunneling (BBT) operation for ultra-low-power (LP) applications. We design a stack structure that is based on the Ge/GaAs heterojunction to realize the vertical BBT operation. The use of vertical BBT operations in devices results in excellent subthreshold characteristics with a reduction in the drain-induced barrier thinning (DIBT) phenomenon. The proposed device with a channel length ($L_{ch}$) of 5 nm exhibits outstanding LP performance with a subthreshold swing (S) of 29.1 mV/dec and an off-state current ($I_{off}$) of $1.12{\times}10^{-11}A/{\mu}m$. In addition, the use of the highk spacer dielectric $HfO_2$ improves the on-state current ($I_{on}$) with an intrinsic delay time (${\tau}$) because of a higher fringing field. We demonstrate a sub-10 nm LP switching device that realizes a good S and lower $I_{off}$ at a lower supply voltage ($V_{DD}$) of 0.2 V.

• Journal of Korean Foot and Ankle Society
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• v.23 no.2
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• pp.58-66
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• 2019

Purpose: To evaluate the efficacy of antibiotic-loaded cement spacers (ALCSs) for the treatment of diabetic foot infections with osteomyelitis as a salvage procedure and to analyze the risk factors of treatment failure. Materials and Methods: This study reviewed retrospectively 39 cases of diabetic foot infections with osteomyelitis who underwent surgical treatment from 2009 to 2017. The mean age and follow-up period were $62{\pm}13years$ and $19.2{\pm}23.3months$, respectively. Wounds were graded using the Wagner and Strauss classification. X-ray, magnetic resonance imaging (or bone scan) and deep tissue cultures were taken preoperatively to diagnose osteomyelitis. The ankle-brachial index, toe-brachial index (TBI), and current perception threshold were checked. Lower extremity angiography was performed and if necessary, percutaneous transluminal angioplasty was conducted preoperatively. As a surgical treatment, meticulous debridement, bone curettage, and ALCS placement were employed in all cases. Between six and eight weeks after surgery, ALCS removal and autogenous iliac bone graft were performed. The treatment was considered successful if the wounds had healed completely within three months without signs of infection and no additional amputation within six months. Results: The treatment success rate was 82.1% (n=32); 12.8% (n=5) required additional amputation and 5.1% (n=2) showed delayed wound healing. Bacterial growth was confirmed in 82.1% (n=32) with methicillin-resistant Staphylococcus aureus being the most commonly identified strain (23.1%, n=9). The lesions were divided anatomically into four groups; the largest number was the toes: (1) toes (41.0%, n=16), (2) metatarsals (35.9%, n=14), (3) midfoot (5.1%, n=2), and (4) hindfoot (17.9%, n=7). A significant difference in the Strauss wound score and TBI was observed between the treatment success group and failure group. Conclusion: The insertion of ALCSs can be a useful treatment option in diabetic foot infections with osteomyelitis. Low scores in the Strauss classification and low TBI are risk factors of treatment failure.

• Horticultural Science & Technology
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• v.30 no.2
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• pp.178-184
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• 2012

This study was carried out to decide ITS (internal transcribed spacer) sequence of some Korean native $Aster$ species and to resolve their relationship among Korean native $Aster$, including $Kalimeris$, $Gymnaster$, $Heteropappus$ genus separated from $Aster$ in a previously study based on the pappus length. We registered 11 ITS sequences of $Aster$ species including $A.$ $glehni$ to GenBank and those sequences were used for the cluster analysis with $Kalimeris$ species. The size of ITS1 was varied from 248 to 256 bp, while ITS2 was varied from 220 to 222 bp. The G + C content of the ITS region ranged from 49.4 to 53.5%. Pairwise comparison results showed that the substitution rate of ITS1 and ITS2 region was 9% and 10%, respectively. $Kalimeris$ sensu strict substitution rate was lower than that of $Aster$ sensu strict species. The strict consensus parsimonious cluster analysis showed $A.$ $tripolium$ is the first branching from the clade and the next is $A.$ $scaber$. The $Kalimeris$ species except for the $A.$ $hispidus$ were grouped into the same clade with high bootstrap value (91%) within $Aster$. $Gymnaster$ and $Heteropappus$ that has been classified by morphological characters were also grouped into broad sense $Aster$ clade. These results implied these three genera could be merged together into $Aster$ based on the ITS sequences.