• Ocean and Polar Research
• /
• v.24 no.4
• /
• pp.483-490
• /
• 2002

Detailed investigations on both submarine and subaerial volcaniclastic deposits around Dokdo were carried out to identify geomorphologic characteristics, stratigraphy, and associated depositional processes of Dokdo caldera. Dokdo volcano has a gently sloping summit (about 11km in diameter) and relatively steep slope (basal diameter is about 20-25 km) rising above sea level at about 2,270m. We found ragged, elliptical-form of Dokdo caldera with a diameter of about 2km estimated by Chirp (3-11 kHz) sub-bottom profile data and side scan sonar data for the central summit area of Dokdo volcano. We interpreted that the volcaniclastic deposits of Dokdo unconformably consist of the Seodo (west islet) and the Dongdo(east islet) formations based on internal structure, constituent mineral composition, and bedding morphology. The Seodo Formation mainly consisted of massive or inversely graded trachytic breccias (Unit S-I), overlain by fine-grained tuff (Unit S-II), which is probably supplied by mass-wasting processes resulting from Dokdo caldera collapse. The Dongdo Formation consists of alternated units of stratified lapilli tuff and inversely graded basaltic breccia (Unit D-I, Unit D-III, and Unit D-V), and massive to undulatory-bedded basaltic tuff breccias (Unit D-II and Unit D-IV) formed by a repetitive pyroclastic surge and reworking processes. Although, two islets of Dokdo are geographically near each other, they have different formations reflecting their different depositional processes and eruptive stages.

• Journal of Biosystems Engineering
• /
• v.36 no.5
• /
• pp.377-383
• /
• 2011

This study proposed the new method of discerning the assembled parts and presuming the position of central point in a Cowl Cross Bar (CCB) using a Charge-Couple Device (CCD) camera attached to a robot in the auto assembly line. Three control points of an ellipse were decided by three reference points, which were equally distanced. The radii of these reference points were determined by the size of the object, and the repeated presumption secured the precise determination. The comparison of the central point of ellipse presumed by Randomized Hough Transform (RHT) with the part information stored in a database was used for determining the faulty part in an assembly. The method proposed in this study was applied for the real-time inspection of elliptical parts, such as bolt, nut hole and so on, connected to a CCB using a CCD camera. The findings of this study showed that the precise decision on whether the parts are inferior or not can be made irrespective of the lighting condition of industrial site and the noises of the surface of the part. In addition, the defect decision on the individual elliptic parts assembled in a CCB showed more than 98% accuracy within a 500-millisecond period at most.

• Fisheries and Aquatic Sciences
• /
• v.15 no.2
• /
• pp.125-135
• /
• 2012

This study was carried out to understand the correlation between phylogenetic relationships based on 18S rDNA sequences and growth by salinity of Chlorella-like species. The 18S rDNA sequences of 71 Chlorella-like species which were mainly collected from Korean waters were analyzed. The 18S rDNA sequences of Chlorella-like species were divided into three groups (group A, B and C) and group B was further divided into three subgroups (subgroup B-1, B-2 and B-3). Thirty-seven Chlorella-like species in group A grew well at high salinity (32 psu) but the other groups grew well in freshwater. The sequence identities of the species in group A and B were 97.2-99.5%, but those of 6 species in group C ("Chlorella" saccharophila), which contained group I intron sequences region were 75.0-75.4%. Two representative species of each group were cultured at different salinities (0, 16 and 32 psu) to examine the correlation between the molecular phylogenetic groups and the phenotypic characteristics on cell growth and size by different salinities. The size of cell cultured at different salinities varied according to the species of each molecular phylogenetic group. The size of "Chlorella" saccharophila in group C was bigger and more obviously elliptical rather than that of the other Chlorella-like species. Considering the results on molecular and phenotypic characteristics, the group A and B belonged to Chlorellaceae, but group C was distinctly different from them.

• Journal of Astronomy and Space Sciences
• /
• v.29 no.1
• /
• pp.51-55
• /
• 2012

A few high-mass X-ray binaries-consisting of an OB star plus compact companion-have been observed by Fermi and ground-based Cerenkov telescopes like High Energy Stereoscopic System (HESS) to be sources of very high energy (VHE; up to 30 TeV) ${\gamma}$-rays. This paper focuses on the prominent ${\gamma}$-ray source, LS 5039, which consists of a massive O6.5V star in a 3.9-day-period, mildly elliptical ($e{\approx}0.24$) orbit with its companion, assumed here to be an unmagnetized compact object (e.g., black hole). Using three dimensional smoothed particle hydrodynamics simulations of the Bondi-Hoyle accretion of the O-star wind onto the companion, we find that the orbital phase variation of the accretion follows very closely the simple Bondi-Hoyle-Lyttleton (BHL) rate for the local radius and wind speed. Moreover, a simple model, wherein intrinsic emission of ${\gamma}$-rays is assumed to track this accretion rate, reproduces quite well Fermi observations of the phase variation of ${\gamma}$-rays in the energy range 0.1-10 GeV. However for the VHE (0.1-30 TeV) radiation observed by the HESS Cerenkov telescope, it is important to account also for photon-photon interactions between the ${\gamma}$-rays and the stellar optical/UV radiation, which effectively attenuates much of the strong emission near periastron. When this is included, we find that this simple BHL accretion model also quite naturally fits the HESS light curve, thus making it a strong alternative to the pulsar-wind-shock models commonly invoked to explain such VHE ${\gamma}$-ray emission in massive-star binaries.

• Journal of Advanced Navigation Technology
• /
• v.24 no.5
• /
• pp.444-449
• /
• 2020

I proposed small ambulatory robot actuators using piezoelectric benders. In order to make the motion of the biomimetic robot legs similar to the movements of the cockroaches or similar insects, two pairs of legs in the diagonal direction in the four leg structures are required to make the same movement. And elliptical displacement is realized by taking into account horizontal and vertical displacement of multimode oscillations and driving them by electrical signals with differences step by step, for example of 90° the T-shaped robot actuator showed wide range of speed (From 2 mm/sec. up to 266 mm/sec.) and ability of transportation (up to 10 g with 50 mm/s). Locomotive performance of the robot was competitive to the preceding robots, and moreover, the modular type actuators of a segmented myriapods robot could be added and removed for different tasks or performances.

• Journal of Astronomy and Space Sciences
• /
• v.16 no.1
• /
• pp.11-20
• /
• 1999

In this paper all the photoelectric times of minimum for the triple star SW Lyn have been analyzed in terms of light-time effect due to the third-body and secular period decreases induced by mass transfer process. The light-time orbit determined recently by Ogloza et al.(1998) were modified and improved. And it is found that the orbital period of SW Lyn have been decreasing secularly. The third-body revolves around the mass center of triple stars every $5^y.77$ in a highly eccentric elliptical orbit(e=0.61). The third-body with a minimum mass of $1.13M_{odot}$ may be a binary or a white dwarf. The rate of secular period-decrease were obtained as ${Delta}P/P=-12.45{ imes}10^{-11}$, implying the mass-transfer from the massive primary star to the secondary. The mass losing rate from the primary were calculated as about $1.24{ imes}10^{-8}M_{odot}/y$. It is noticed that the mass-transfer in SW Lyn system is opposite in direction to that deduced from it's Roche geometry by previous investigators.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.33 no.5 s.112
• /
• pp.94-103
• /
• 2005

This study was carried out to investigate growth and morphological characteristics of leaf, flower and winter bud of Corylopsis species such as C. coreana, C. spicata, C. sinensis, C. willmottiae, C. willmottiae 'Spring Purple', C. wilsonii, C. spicata 'Yellow Spring', C. gotoana, and C. vechiana. In the Corylopsis species, C. coreana, C. willmottiae, and C. vetchiana had larger flowers, longer flower cluster, and more flowers than other species. C. sinensis and C. veitchiana had fragrant flowers. In addition, species with beautiful leaf color were C. spicata 'Yellow spring' with yellow color and C. willmottiae 'Spring purple' with purple color, which eventually changed to green. The winter bud of C. sinensis, C. willmottiae, C. willmottiae 'Spring Purple', and C. vechiana were oval and different from those of other species. Comparison of the morphological characteristics among C. coreana, C. spicata, and C. sinensis, C. coreana showed they had earlier flowering dates and brighter yellow flowers than those of other species. Flower cluster of C. sinensis was shortest, but it had most number of flowers and fragrance. In addition, the winter buds of C. coreana and C. spicata with elliptical shape were different from that of C. sinensis with oval shape. Therefore, based on these characteristics, the following Corylopsis species were found to be promising as woody landscape plants: C. coreana, C. sinensis, C. willmottiae 'Spring Purple', C. spicata 'Yellow Spring', and C. vechiana.

• 연구논문집
• /
• s.23
• /
• pp.127-140
• /
• 1993

The drive pulley, which is employed for loading and unloading raw materials in a steel mill, is usually manufactured by use of various welding processes. In this study the weldment in the pulley, in which TIG and $CO_2$ welding processes are used, has been analyzed from view point of fracture mechanics. Fracture toughness tests have been performed according to ASTM E813. A servo-hydraulic testing machine (10kN) has been employed. Also the crack propagation tests (Mode I) have been performed with compact tension specimen in compliance with ASTM E647. To predict the critical crack size in the weldment, finite element stress analysis for the drive pulley under real operating conditions have been performed. In addition, the residual stresses at the weldment and in heat-affected zone have been obtained by hole drilling method. The planar critical crack size have been predicted for the drive pulley by considering the stress analysis results and the residual stresses due to welding process. For the drive pulley considered in this study, it has been concluded that the most important factor in determining the critical crack size is the welding residual stress in the transverse direction. Also the effect of stress concentration at the root of the weldment have been noticeable. For the planar crack, the fatigue crack growth life from an initial crack size of 2mm to the critical crack size obtained as in the above have been predicted. The predicted lives were between 55, 900 and 72, 000 cycles depending on the shape of the elliptical crack. The predicted lives were in fairly good agreement for the drive pulley considered in this study.

• Mycobiology
• /
• v.38 no.4
• /
• pp.249-255
• /
• 2010

We identified Lacrymaria velutina of the Coprinaceae in Korea. The unusually large and sturdy fruiting body, fibrillose to fibrillose-scaly cap and stalk without a volva with an obscure superior hairy ring zone or hairy annulus, and blackish brown, warted spores distinguished this species from closely related Psathyrella species. An illustrated account of the microscopic traits is presented. Fruiting bodies with obtusely hemispherical caps, 2.5~6 cm, becoming convex with age; surface dry, densely fibrillose-scaly with split margin; stipe, 4.5~6 cm, equal, hollow, fibrillose, dry, whitish above the superior ring zone, light brown below; crowded gills, adnexed, dark black at maturity. Pileipellis typically cellular with the gill edge appearing white and beaded. Blackish brown basidiospores that discolor in concentrated sulfuric acid. Spores elliptical, warted, $9\sim11{\times}6\sim8{\mu}m$, with prominent snout-like germpores. Cheilocystidia abundant, $57\sim68{\times}19\sim25{\mu}m$, and narrowly elongated clavate, often clustered in threes or fours. Pleurocystidia rarely present, $45\sim47.5{\times}12\sim13{\mu}m$, and clavate to utriform. This trait distinguishes our sample as L. velutina from other Psathyrella spp. of the Coprinaceae, which have smooth spores. This taxon was clarified by the observation that Psathyrella spores fade in concentrated sulfuric acid. A molecular phylogenetic study revealed that our specimen was Lacrymria velutipes, which is closely related to Lacrymaria lacrymabunda. Moreover, those two species are clearly distinguishable from other Psathyrella species, which agreed with the morphologically distinctive traits described above. We believe that this is the first report of this taxon, which has not been described in Korea.

• Korean Journal of Veterinary Research
• /
• v.38 no.2
• /
• pp.246-257
• /
• 1998

Endocrine cells in the thymus of duck(Anas platyrhynchos platyrhyncos, Linne) were studied immunohistochemically from 23 days of incubation to 32 weeks of age. Somatostatin-, growth hormone(GH)-, gastrin/cholecystokinin(Gas/CCK)-, polypeptide YY(PYY)-, S-100 protein(S-100 P)-, dopamine-, serotonin(5-HT)-, and bovine chromogranin (BCG)-immunoreactive cells were detected in the duck thymus by the PAP techniques. These immunoreactive cells were observed in the medulla and in the juxtacortical medulla. No immunoreactivity of calcitonin and bovine pancreatic polypeptide(BPP) antiserum were observed. The argyrophil cells by Grimelius techniques were observed from 23 days of incubation to 32 weeks of age and peaked in 5 weeks of age. In the early develpmental stage, the argyrophil cells were distributed only in the medulla, while these cells were distributed mainly in the medulla and a few cells were distributed in the corticomedullary junction from 3 weeks of age. These immunoreactive cells were generally round, oval and elliptical and occasionally spindle, polygonal and polymorphous with the long cytopslasmic processes in shape. The present study suggests that the intrathymic endocrine cells may associate with the functional maturation of T-lymphocytes on the establishment of immunity. The further study will be needed to elucidate the function of these thymic endocrine cells.