• Journal of the Korean Society of Tobacco Science
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• v.14 no.1
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• pp.12-23
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• 1992

This experiment was conducted to determine the optimum dosage of gamma rays for inducing artificial mutation of several mutant characters in the flue-cured tobacco. 1) In Hicks and BY 104, the gammarays irradiation has no significantly different effect on seed germination from the control. However, the average dosage for 50% growth inhibition was 25-30kr for all the varieties tested, which inhibition 46-52% and 43-57% of the seedling growths for Hicks and BY 104, respectively. 2) A mutant line 83H-5 was selected from Hicks by irradiation gamma ray at the level of 30kr. It has white flower, more resistance to bacterial wilt, Pssudomonas solanacearum, lower plant and stalk height, narrower leaf width, larger leaf shape index(lento width) and later days to flower when compared with the original variety Hicks. 3) White flower was recessive to pink flower in F, and Br (F1 X Hicks) progenies. F2 population of the cross gave segregation ratio of 3 pink flower:1 white flower, and B, (F1 X 83H-5) Population gave 1:1 ratio. Results showed that the white flower character is governed by a single recessive gene.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.6
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• pp.670-678
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• 2010

An ecological investigation was conducted in winter from November 2007 to February 2008, around Wangdol Reef in the East Sea to analyze the population structure and fecundity of Chinoecetes opilio. The sex ratio was 30.11:69.89% (female:male) in November, 62.03:37.97% in December, 37.59:62.41% in January and 14.69:85.31% in February. Regression equations indicated highly positive relationships between size and weight parameters (carapace length, width, total weight). During the sampling period ovigerous females were continuously collected. The percentage of ovigerous females was 96% in November, 90.57% in December 89.80% in January, and 88.46% in February. The average number of embryos was 64,800. The regression equation between carapace width and the number of embryos was y = 2.6805x - 0.9182 ($R^2$ = 0.7166). Embryo volume increased as embryo development proceeded. The mean size of an embryo was 0.72 mm. Embryo volume ranged from 0.42 to $0.84\;m^3$ during embryo developmental stages 1 to 3.

• Korean Journal of Ecology and Environment
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• v.38 no.spc
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• pp.1-7
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• 2005

To resolve some of the most pressing uncertainties of Peridinium identity, morphological characteristics of Korean Peridinium were examined using light and scanning electron microscopy. The Peridinium samples were collected from three different regions of Juam, Sang-sa and Togyo Reservoirs, when seasonal blooms occurred. Formula of the epithecal plate was recorded with 7 precingular, 3 intercalary, and 4 apical plates (4', 3a, 7"). An apical pore, 3 ${\sim}$ 5 ${\mu}m$ in size, was apparently present. The cingulum was easily observed under light microscope, and was considerably offset by about 15 ${\mu}m$ (2 ${\sim}$ 3 times per cingulum width). The sulcus was straight longitudinally and widened apparently towards the antapex. None of spine was found on the surface of the thecal plates on scanning electron micrographs. The average body length was 50.4 ${\mu}m$ with a range of 29 ${\sim}$ 63 ${\mu}m$. The geometric dimension, as designated to the body length:width ratio, was found from calculation to be 1.12 with a range of 1.00 ${\sim}$ 1.35, therefore, the cell was shown slightly elongated. Based on their morphology, the causative organisms of red tides in three different Korean waters were identified as P. bipes f. occultatum, which was reported for the first time in Korea.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.4
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• pp.397-406
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• 2009

This study was conducted to monitor the floc sizes forming in the mixing zone in the water treatment plant. The dosing amount of poly aluminium chloride(PAC) was determined by particle dispersion analyzer(iPDA) in the lab and field scale test. During a field test period, PAC coagulant was used and the raw water was taken from Nakdong river. PAC wad diluted to activate the coagulant, leading to bring the more homogeneous dispersion in the shorter time. To monitor the floc sizes, the unit of floc size index(FSI) was used. With increasing of raw water turbidity, FSI value was increased. Also, the increased dosing amount of PAC brought the increased FSI and with overdosing of coagulant was in turn decreased. When the PAC was fed into the raw water after dilution in a field scale test, the width of FSI was narrower compared with the feeding of the mother liquor of PAC, implying that the formed flocs are denser and more uniform sizes. The width of FSI in average was varied on depending on the basicity of coagulant. Also, dF value, fractal dimension was evalued with the different coagulants, showing from 2.01 to 2.03. On-line floc monitor was effective for the optimal dosing in the drinking water plant.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.96.1-96.1
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• 2011

Halo coronal mass ejections (HCMEs) are major cause of the geomagnetic storms. To minimize the projection effect by coronagraph observations, we consider two CME cone models: an ice-cream cone model and an asymmetric cone model. These models allow us to determine three dimensional parameters of HCMEs such as radial speed, angular width, and the angle between sky plane and cone axis. In this study, we compare these parameters obtained from both models using 50 well-observed HCMEs from 2001 to 2002. Then we obtain the root mean square error (RMS error) between measured projection speeds and estimated ones for the models. As a result, we find that the radial speeds obtained from the models are well correlated with each other (R=0.89), and the correlation coefficient of angular width is 0.68. The correlation coefficient of the angle between sky plane and cone axis is 0.42, which is much smaller than what is expected. The reason may be due to the fact that the source locations of the asymmetric cone model are assumed to be near the center. The average RMS error of the asymmetric cone model (86.2km/s) is slightly smaller than that of the ice-cream cone model (88.6km/s).

• Carbon letters
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• v.11 no.4
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• pp.325-331
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• 2010

This study investigates the effect of filler content (wt%), presence of interphase and agglomerates on the effective Young's modulus of polypropylene (PP) based nanocomposites reinforced with exfoliated graphite nanoplatelets ($xGnP^{TM}$) and carbon nanotubes (CNTs). The Young's modulus of the composites is determined using tensile testing based on ASTM D638. The reinforcement/polymer interphase is characterized in terms of width and mechanical properties using atomic force microscopy which is also used to investigate the presence and size of agglomerates. It is found that the interphase has an average width of ~30 nm and modulus in the range of 5 to 12 GPa. The Halpin-Tsai micromechanical model is modified to account for the effect of interphase and filler agglomerates and the model predictions for the effective modulus of the composites are compared to the experimental data. The presented results highlight the need of considering various experimentally observed filler characteristics such as agglomerate size and aspect ratio and presence and properties of interphase in the micromechanical models in order to develop better design tools to fabricate multifunctional polymer nanocomposites with engineered properties.

• Korean Journal of Materials Research
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• v.30 no.3
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• pp.149-154
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• 2020

A powder-in-sheath rolling method is applied to the fabrication of a carbon nano tube (CNT) reinforced copper composite. A copper tube with outer diameter of 30 mm and wall thickness of 2 mm is used as sheath material. A mixture of pure copper powder and CNTs with a volume content of 3 % is filled in a tube by tap filling and then processed to an 93.3 % reduction using multi-pass rolling after heating for 0.5 h at 400 ℃. The specimen is then sintered for 1h at 500 ℃. The relative density of the 3 vol%CNT/Cu composite fabricated using powder in sheath rolling is 98 %, while that of the Cu powder compact is 99 %. The microstructure is somewhat heterogeneous in width direction in the composite, but is relatively homogeneous in the Cu powder compact. The hardness distribution is also ununiform in the width direction for the composite. The average hardness of the composites is higher by 8Hv than that of Cu powder compact. The tensile strength of the composite is 280 MPa, which is 20 MPa higher than that of the Cu powder compact. It is concluded that the powder in sheath rolling method is an effective process for fabrication of sound CNT reinforced Cu matrix composites.

• Plant Resources
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• v.5 no.1
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• pp.45-50
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• 2002

Korean cultivars of buckwheat(Fagopyrum esculentum Moench.) was crossed with Canadian cultivars in order to improve seed yield as well as leaf production of buckwheat for using as food and medicine. The agronomic characteristics and rutin contents of F$_2$ hybrids are investigated for further selection of superior lines. Dry weight per plant was the highest in a line 1110(6.71g) and leaf weight per plant was the highest in a line 1110(1.91g). Hybrid seeds were 0.55 - 0.70cm long and 0.37 - 0.47cm wide on average. 100 seeds weight ranged from 2.57g to 3.58g. Line 1076 produced the longest seeds(0.70cm) and line 1186 was the longest in seed width. Line 1196 showed the highest 100 seeds weight(3.58g). The highest frequency of the LWR(length/width rate) was 0.66~0.70, indicating that seed shape of the hybrids was mostly oval. Line 1087 showed the highest contents of rutin(77.26ppm). Lines 1090 and 1181 contained respectively rutin of 54.76ppm and 54.35ppm in the seeds. From the yield and rutin point of view, the most superior lines was line 1087 among the lines used for this study.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.25 no.2
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• pp.535-544
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• 1995

The purpose of this study was comparision of conventional tomography with reformatted computed tomography for dental implant in locating the mandibular canal. Five dogs were used and after conventional tomographs and reformatted computed tomographs were taken, four dentist traced all films. Mandibles were sectioned with 2mm slice thickness and the sections were then radiographed(contact radiography). Each radiographic image was traced and linear measurements were made from mandibular canal to alveolar crest, buccal cortex, lingual cortex, and inferior border. Following results were acquired : 1. Reformatted computed tomographs were exacter than conventional tomography by alveolar crest to canal length of -0.6mm difference between real values and radiographs. 2. The average measurements of buccal cortex to mandibular canal width and lingual cortex to mandibular canal width of conventional tomographs were exacter than reformatted computed tomographs, but standard deviations were higher than reformatted computed tomographs. 3. Standard deviations of reformatted computed tomographs were lower than conventional tomographs at all comparing sites 4. At reformatted computed tomography 62.5％ of the measurements performed were within. : filmm of the true value, and at conventional tomography 24.1％ were. 5. Mandibular canal invisibiity was 0.8％ at reformatted computed tomography and 9.2％ at conventional tomography. Reformatted computed tomography has been shown to be more useful radiographic technique for assessment of the mandibular canal than conventional tomography.

• Journal of the Semiconductor & Display Technology
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• v.15 no.1
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• pp.27-32
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• 2016

A new lane detection algorithm is proposed for the analysis of DNA fingerprints from a polymerase chain reaction (PCR) gel electrophoresis image. Although several research results have been previously reported, it is still challenging to extract lanes precisely from images having abrupt background brightness difference and bent lanes. We propose an edge based algorithm for calculating the average lane width and lane cycle. Our method adopts sub-pixel algorithm for extracting rising-edges and falling edges precisely and estimates the lane width and cycle by using k-means clustering algorithm. To handle the curved lanes, we partition the gel image into small portions, and track the lane centers in each partitioned image. 32 gel images including 534 lanes are used to evaluate the performance of our method. Experimental results show that our method is robust to images having background difference and bent lanes without any preprocessing.