• Investigative Magnetic Resonance Imaging
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• v.12 no.2
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• pp.131-141
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• 2008

Purpose : To investigate the feasibility and accuracy of Proton Resonance Frequency (PRF) shift based magnetic resonance (MR) temperature mapping utilizing the self-developed center array-sequencing phase unwrapping (PU) method for non-invasive temperature monitoring. Materials and Methods : The computer simulation was done on the PU algorithm for performance evaluation before further application to MR thermometry. The MR experiments were conducted in two approaches namely PU experiment, and temperature mapping experiment based on the PU technique with all the image postprocessing implemented in MATLAB. A 1.5T MR scanner employing a knee coil with $T2^*$ GRE (Gradient Recalled Echo) pulse sequence were used throughout the experiments. Various subjects such as water phantom, orange, and agarose gel phantom were used for the assessment of the self-developed PU algorithm. The MR temperature mapping experiment was initially attempted on the agarose gel phantom only with the application of a custom-made thermoregulating water pump as the heating source. Heat was generated to the phantom via hot water circulation whilst temperature variation was observed with T-type thermocouple. The PU program was implemented on the reconstructed wrapped phase images prior to map the temperature distribution of subjects. As the temperature change is directly proportional to the phase difference map, the absolute temperature could be estimated from the summation of the computed temperature difference with the measured ambient temperature of subjects. Results : The PU technique successfully recovered and removed the phase wrapping artifacts on MR phase images with various subjects by producing a smooth and continuous phase map thus producing a more reliable temperature map. Conclusion : This work presented a rapid, and robust self-developed center array-sequencing PU algorithm feasible for the application of MR temperature mapping according to the PRF phase shift property.

• Investigative Magnetic Resonance Imaging
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• v.18 no.2
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• pp.107-119
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• 2014

Purpose : To efficiently evaluate phased array coil performance using a software tool box with which we can make visual comparison of the sensitivity of every coil element between the real experiment and EM simulation. Materials and Methods: We have developed a $C^{{+}{+}}$- and MATLAB-based software tool called Phased Array Coil Evaluator (PACE). PACE has the following functions: Building 3D models of the coil elements, importing the FDTD simulation results, and visualizing the coil sensitivity of each coil element on the ordinary Cartesian coordinate and the relative coil position coordinate. To build a 3D model of the phased array coil, we used an electromagnetic 3D tracker in a stylus form. After making the 3D model, we imported the 3D model into the FDTD electromagnetic field simulation tool. Results: An accurate comparison between the coil sensitivity simulation and real experiment on the tool box platform has been made through fine matching of the simulation and real experiment with aids of the 3D tracker. In the simulation and experiment, we used a 36-channel helmet-style phased array coil. At the 3D MRI data acquisition using the spoiled gradient echo sequence, we used the uniform cylindrical phantom that had the same geometry as the one in the FDTD simulation. In the tool box, we can conveniently choose the coil element of interest and we can compare the coil sensitivities element-by-element of the phased array coil. Conclusion: We expect the tool box can be greatly used for developing phased array coils of new geometry or for periodic maintenance of phased array coils in a more accurate and consistent manner.

• Journal of Life Science
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• v.18 no.11
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• pp.1592-1599
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• 2008

The $\beta$-lactamase gene was cloned into E. coli DH5$\alpha$ from Bacillus sp. J105 with strong resistance against $\beta$-lactam antibiotics. The chromosomal DNA was partially digested with Sau3AI and ligated to BamHI digested pLAFR3. $\beta$-Lactamase positive clones were obtained by using in vitro packaging kit. The pKL11-${\Delta}4.6$ with $\beta$-lactamase activity was obtained by subcloning of the recombinant plasmid ($\beta$-lac +). The 6.5 kb fragment in the subcloned plasmid was sequenced. The DNA fragment that contains the $\beta$-lactamase gene encodes 309 amino acids. The 0.17 kb upstream region was similar to those of B. thuringinesis and B. cereus with 97% identity. The deduced amino acids sequence was also similar to those of $\beta$-lactamase from B. thuringinesis and B. cereus with 97% and 94% identity, respectively. The phylogenetic tree also showed the relationships of the $\beta$-lactamase gene of Bacillus sp. J105 to genetically related that of other Bacillus strains. Analysis of expression pattern of the pKL11-${\Delta}4.6$ in E. coli, revealed that the secretion efficiency of $\beta$-lactamase was $4{\sim}5%$ and the molecular weight was as same as that of original $\beta$-lactamase (31 kDa) from Bacillus sp. J105.

• Journal of fish pathology
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• v.30 no.2
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• pp.89-96
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• 2017

The majority of freshwater ornamental fish are imported and distributed domestically, causing high risk of exposure to exotic pathogens and drug resistant bacteria in Korea. Aeromonas hydrophila is known as a common species of fresh water bacteria and opportunistic fish pathogen, as well as a species causing zoonotic infection. In this study, we isolated motile aeromonads from various imported freshwater ornamental fish and studied the characters of the isolates. Imported freshwater ornamental fish were purchased on day 1 after the fish were deposited in the aquarium. Bacteria were isolated from the liver, kidney and spleen of fish using 0.5% NaCl containing tryptic soy agar medium. Bacteria were grouped on the basis of their morphological characteristics. The colonies with clear zone on starch-ampicillin agar (SA agar) were tentatively identified as Aeromonas spp. Two hundred and twenty-six strains, about 70% of total isolates were assumed to be Aeromonas spp. Nine isolates were further identified based on the result of the API 20E test and PCR using primers specific for A. hydrophila 16S rRNA gene. The isolates were identified as A. hydrophila and the API 20E test showed differences in trisodium citrate, D-sucrose, D-melibiose, amygdalin and L-arabinose availability between the nine isolates and standard A. hydrophila. The susceptibilities of the isolated bacteria to 10 antibacterial agents were confirmed by the disk diffusion method. Isolated strains were found to be resistant to amoxicillin and ampicillin and sensitive to florfenicol. However, 7 isolates showed multiple drug resistances to erythromycin, oxytetracycline, nalidixic acid etc. Pathogenicity of the isolates was determined by the artificial challenge test on goldfish (Carassius auratus). Three isolates caused 60 ~ 80% mortality in goldfish within 5 days after the initiation of challenge. These results indicate that multiple drug resistant, highly pathogenic and exotic A. hydrophila can spread to domestic aquarium and the preventive treatment of fish before sale is necessary.

• Clinical and Experimental Reproductive Medicine
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• v.31 no.2
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• pp.105-110
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• 2004

Objectives: Despite severe oligospermia, males with Y chromosome microdeletion can achieve conception through ICSI (Intracytoplasmic Sperm Injection). However, ICSI may not only result in the transmission of microdeletions but also the expansion of deletion to the offspring. The purpose of this study was to screen vertical transmission, expansion of microdeletions and de novo deletion in male fetuses conceived by ICSI. Materials and Methods: A total of 32 ICSI treated patients with their 33 (a case of twin) male fetuses conceived by ICSI were used to make this study group. Sequence-tagged sites (STSs)-based PCR analyses were performed on genomic DNA isolated from peripheral blood of fathers and from the amniocytes of male fetuses. Ten primer pairs namely, sY134, sY138, MK5, sY152, sY147, sY254, sY255, SPGY1, sY269 and sY158 were used. The samples with deletions were verified at least three times. Results: We detected a frequency of 12.5% (4 of the 32 patients) of microdeletions in ICSI patients. In 4 patients with detected deletions, two patients have proven deletions on single STS marker and their male fetuses have the identical deletion in this region. Another two patients have two and three deletions, but their male fetuses have more than 3 deletions which include deletions to their father's. Meanwhile, seven male fetuses, whose fathers were analyzed to have all 10 STS markers present, have deletions present in at least one or more of the markers. Conclusions: Although the majority of deletions on the Y chromosome are believed to arise de novo, in some cases a deletion has been transmitted from the fertile father to the infertile patient. In other cases the deletion was transmitted through ICSI treatment, it is likely that one sperm cell is injected through the oocyte's cytoplasm and fertilization can be obtained from spermatozoa. Our tests for deletion were determined by PCR and our results show that the ICSI treatment may lead to vertical transmission, expansion and de novo Y chromosome microdeletions in male fetuses. Because the sample group was relatively small, one should be cautious in analyzing these data. However, it is important to counsel infertile couples contemplating ICSI if the male carries Y chromosomal microdeletions.

• Asian Journal of Turfgrass Science
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• v.20 no.1
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• pp.65-76
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• 2006

Scz1, an isolate of Sclerotinia homoeocarpa, was recently reported as a novel pathogen responsible for dollar spot disease in Zoysiagrass, a warm season turfgrass. Scz1 possessed different characteristics on mycelial pigment, mycelial affinity and host pathogenecity compared to those of Scb1, a typical isolate, obtained from creeping bentgrass, a cool season turfgrass. In this study, only three isolates, Scz1, Scz2(another analogous isolate of Sclerotinia homoeocarpa from zoysiagrass), and Scb1, were examined at the molecular level using the internal transcribed spacer(ITS) and random amplified polymorphic DNA(RAPD) assays to verify their identification and genetic variation. As a result of ITS assay, partial ITS sequences of three isolates showed 94-97% similarity with a standardized ITS sequence of S. homoeocarpa registered on BLAST. In the analysis of RAPD, range value through similarity matrix was 0.167 between Scz1 and Scb1, 0.139 between Scz2 and Scb1, and 0.713 between Scz1 and Scz2, respectively. Furthermore, tendegram analysis indicated that Scz1 and Scz2, unlike Scb1, were clustered together as accompanying a high genetic similarity. In in vitro fungicide bioassay, $EC_{50}$ value representing the sensitivity degree to propiconazole, a well-known fungicide for dollar spot disease, was 0.012 ${\mu}g/ml$ for Sczl, 0.003 ${\mu}g/ml$ for Scz2, and 0.030 ${\mu}g/ml$ for Scb1. From all data taken, we concluded that both Scz1 and Scz2 belonged to one group of S. homoeocarpa, since they exhibit the same host range and high level of genetic similarity, whereas their chemical competences to a fungicide were different. This study would provide further approach for assessing genetic diversity of S. homoeocarpa isolates as well as characterizing individual isolate against chemical exposure.

• Korean Journal of Plant Resources
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• v.30 no.5
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• pp.522-534
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• 2017

This study was investigated genetic variation in 24 Taraxacum accessions from various regions in South Korea based on the sequences of two chloroplast DNA (cpDNA) regions (trnL-trnF and rps16-trnK). T. mongolicum, T. officinale, and T. laevigatum were triploid, and T. coreanum and T. coreanum var. flavescens were tetraploid. The trnL-trnF region in native Korean dandelions (T. mongolicum, T. coreanum, and T. coreanum var. flavescens) were ranged from 931 to 935 bp in length, and that of naturalized dandelions were ranged from 910 bp (T. officinale) to 975 bp (T. laevigatum) in length. The rps16-trnK region in T. mongolicum, T. coreanum, T. coreanum var. flavescens, T. officinale, and T. laevigatum was 882-883 bp, 875-881 bp, 878-883 bp, 874-876 bp, and 847-876 bp, respectively, in length. The sequence similarity matrix of the trnL-trnF region ranged from 0.860 to 1.00 with an average of 0.949, and that of the rps16-trnK region ranged from 0.919 to 1.000 with an average of 0.967. According to the phylogenetic analysis, the Korean native taxa and naturalized taxa were divided independent clade in two cpDNA region. T. coreanum var. flavescens clustered only with T. coreanum, and there were no significant differences in their nucleotide sequences. The finding that two accessions (T. coreanum; Jogesan, T. mongolicum; Gangyang) had a high level of genetic variation suggests their utility for breeding materials.

• The Journal of the Petrological Society of Korea
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• v.15 no.2 s.44
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• pp.49-59
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• 2006

This study clarifies the deformation history of Precambrian metamorphic rocks of Sobaegsan Massif (Wonnam Formation, Pyeonghae granite gneiss, Hada leucogranite gneiss) in Giseong-myeon area, Uljin-gun, Korea. It is based on the geometric and kinematic features and the developing sequence of multi-deformed rock structures. It also reviews the extension of Yecheon Shear Zone and the relative occurrence time of each deformation phase from previous researches. It suggests that the geological structure was formed at least through five phases of deformation after formation of their gneissosity or schistosity. (1) The first phase of deformation took placed under compression of ENE-WSW direction, forming NNW trending regional foliation and very tight isoclinal fold. The general trend of gneissosity or schistosity is inferred to be ENE before the first phase of deformation, being rearranged into NNW by the isoclinal folding. (2) The second phase of deformation formed ENE trending regional foliation and tight, isoclinal, rootless intrafolial folds under compression of NNW-SSE direction [occurrence time: after deposition (Permian age) of Dongsugok Formation, Pyeongan Croup, Janggunbong area]. (3) The third phase of deformation occurred by dextral ductile shearing on the regional foliation, forming stretching lineation of ENE trend and S-C mylonitic structure (after intrusion of Hesozoic homblende granite, Sangunmyeon area-before intrusion of Mesozoic Chunyang granite, Janggunbong area). (4) The fourth phase occurred under (E)NE-(W)SW compression, forming (N)NW trending open fold. (5) The fifth phase took place under N-S compression, forming NNE and NNW trending conjugate strike-slip faults, E-W trending thrust-slip faults, and drag folds related to these fault movements. The deformed structures of fourth and fifth phases result from tectonic movement associated with the developing of the Gyeongsang Basin in Cretaceous age, and it partially rearranged the general ENE trend of the regional foliation in the study area. It also suggests that the Yecheon Shear Zone of E-W trending extends into this area but the ductile shear deformation is weakly developed.

• The Journal of the Petrological Society of Korea
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• v.7 no.2
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• pp.132-145
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• 1998

The coal-bearing siliciclastic rocks of the Lower Permian Jangseong Formation, Samcheog coalfield, represent a megacyclothem which shows cyclic repetitions of sandstone, shale, coaly shale, and coals. Petrographic, geochemical, and SEM studies for sandstone samples, and XRD analysis for clay minerals were carried out to understand diagenesis in the sandstones of the Jangseong Formation. The Jangseong sandstones are composed of 60% quartz (mainly monocrystalline quartz) and 36% clay matrix and cement with minor amounts of feldspar, lithic fragments and accessory minerals (less than 4%). Jangseong sandstones are classified mostly as quartzwackes and partly as lithic graywackes according to the scheme of Dott(1964). The textural relationships between authigenic minerals and cements in thin sections and SEM photomicrographs suggest the paragenetic sequence as follows; (1) mechanical compaction, (2) cementation by quartz overgrowth, (3) formation of authigenic clay minerals (illite, kaolinite), (4) dissolution of framework grains and development of secondary porosity, and (5) later-stage pore-filling by pyrophyllite. We propose that these diagenetic processes might be due to organic-inorganic interaction between the dominant framework grains and the formation water. The Al, Si ions and organic acid, derived from dewatering of interbedded organic-rich shale and coals, were transported into the Jangseong sandstones. This caused changes in the chemistry of the formation water of the sandstones, and resulted in overgrowth of quartz and precipitation of authigenic clay minerals of kaolinite and illite. The secondary pores, produced during dissolution of clay and framework grains by organic acid and $CO_2$ gas, were conduit for silica-rich solution into the Jangseong sandstones and the influx of silica-rich solution produced the late-stage pyrophyllite after the expanse of kaolinite. The origin of the solution that formed pyrophyllite is not likely to be the organic-rich formation water based on the observation of fracture-filling pyrophyllite in the Jangseong sandstones, but the process of pyrophyllite pore-filling was indirectly related to organic-inorganic interaction.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.3
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• pp.171-183
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• 2016

The effects of weather variations on winter hulless barley were analyzed using data obtained from winter crop situation test at Iksan from 1985 to 2015. The wintering stage in the 16 years from 2000 to 2015 has become colder and shorter than that in the previous 15 years from 1985 to 1999. This has resulted in an early sequence of regrowth date, heading date, and ripening date. Heading date of hulless barley was mostly influenced by regrowth date and period of stem elongation. Futher, the regrowth date and period of stem elongation were strongly negatively correlated with the average air temperature in February and the maximum air temperature in March, respectively. The number of spikes per $m^2$ and 1000-grain weight of Saechalssal cultivated from 2003 to 2015 showed strong positive correlations with yield. In early heading years, yield increased with extended ripening period and with increased 1000-grain weight. There was a strong negative correlation between 1000-grain weight and the average temperature during the ripening period. In the 15 years from 1985 to 1999, warm winters contributed to yield increase with increase in the number of spikes per $m^2$ and a long ripening period. In contrast, in the recent 16 years from 2000 to 2015, the large variability in air temperature during the wintering stage, the decreasing number of spikes per $m^2$ and the steadily increasing air temperature and decreasing precipitation during the ripening stage have caused high temperature stress and yield loss in late heading years.