• Korean Journal of Ichthyology
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• v.11 no.2
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• pp.109-116
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• 1999

The structure of skin of a mud loach Misgurnus anguillicaudatus was described in relation with their histochemical nature from four regions of the skin. The epidermis has a strongly thick layer of two glandular cells, consisting of a elongate mucous cell and club cell, and a thin layer of superficial layer. The secretion of the elongated mucous cell was acid mucopolysaccharides in nature but the club cell did not give any histochemical reaction. A well defined lymphatic system, comprising small lymphocytes was present in the stratum germinativum layer of the epidermis. A pit organ of a pear-shaped structure was present below the epithelial cells and lie directly on the basement membrane. The organ has blood vessels serving the sense organs of the epidermis. There was a definite area showing acid mucopolysaccharides in the stratum laxum layer of the dermis. Small scales are present deep in the dermis except the top of the head. A great number of blood capillaries were found just under basement membrane. These structural features of skin in M. anguillicaudatus seem to be closely related with cutaneous respiration using air.

• Corrosion Science and Technology
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• v.17 no.3
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• pp.109-115
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• 2018

Electrical Resistance Welding (ERW) on a longitudinal seam-welded pipe has been extensively used in oil and gas pipelines. It is well known that the weld zone commonly suffers from grooving corrosion in ERW pipes. In this paper, the grooving corrosion performances of API X65 grade non-sour service (steel-A) and API X70 grade sour gas resistant (steel-B) steel electrical resistance welding pipelines were evaluated. The microstructure of the bondline is composed of coarse polygonal ferrite grains and several elongated pearlites. The elongated pattern is mainly concentrated in the center of the welded area. The grooving corrosion test and electrochemical polarization test were conducted to study the corrosion behavior of the given materials. A V-shaped corrosion groove was found at the center of the fusion zone in both the steel-A and steel-B ERW pipes, as the corrosion rate of the bondlines is higher than that of the base metal. Furthermore, the higher volume fraction of pearlite at the bondline was responsible for the higher corrosion rate at the bondline of both types of steel.

• Animal cells and systems
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• v.2 no.4
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• pp.495-500
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• 1998

D-type G1 cyclins are known to be crucial for the progression of mitotic cell cycle in mammals. Although many studies have been performed to elucidate the roles of D-type cyclins, it is largely unknown whether D-type cyclins are directly involved in the regulation of meiotic germ cell development. In the present study, we examined the expression patterns of D-type cyclins (cyclin D1 and D3) during male germ cell development by northern blot and in situ Hybridization analyses. In the adult testes, we detected a 4.2 kb cyclin D1 mRNA and two different sizes (2.3 kb and 1.8 kb) of cyclinD3 mRNAs. The short form of the cyclin D3 transcript was testis-specific. Along with the testicular development, expression of cyclin D3 mRNA was increased whereas cyclin D1 mRNA was gradually decreased. in situ hybridization study also revealed that the expression of cyclin D3 was restricted to the postmeiotic germ cells. Furthermore, the 2.3 kb transcript was highly expressed in the round spermatids and decreased in the elongated spermatids/residual bodies, while the 1.8 kb transcript was expressed in elongated spermatids/residual bodies more abundantly. Sucrose-gradient separation of polysomal RNA fractions demonstrated that some portions of the 2.3 kb transcript are translationally active, while the 1.8 kb transcript is likely to be inactive. Taken together, the present data suggest a functional importance of cyclin D3 expression in the differentiated postmeiotic male germ cells.

• Parasites, Hosts and Diseases
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• v.41 no.1
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• pp.17-25
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• 2003

The tegumental ultrastructure of juvenile and adult Himasthla alincia (Digenea: Echinostomatidae) was observed by scanning electron microscopy. One-, 5- (juveniles) and 20-day-old worms (adults) were harvested from chicks experimentally fed metacercariae from a bivalve, Mactra veneriformis. The juvenile worms were elongated and cu wed ventrally. The head crown bore 31 collar spines, arranged in a single row. The lip of the oral sucker had 12 paired, and 3 single type 1 sensory papillae, and the ventral sucker had about 25 type II sensory papillae. The anterolateral surface between the two suckers was densely packed with tegumental spines with 4-7 pointed tips. The adult worms were more elongated and filamentous, and had severe transverse folds over the whole body surface. On the head crown and two suckers, type 1 and 11 sensory papillae were more densely distributed than in the juvenile worms. Retractile brush-like spines, with 8-10 digits, were seen on the anterolateral surface, whereas claw-shaped spines, with 2-5 digits, were sparsely distributed posteriorly to the ventral sucker The cirrus characteristically protruded out, and was armed with small spines distally. The surface ultrastructure of H. alincia was shown to be unique among echinostomes, especially in the digitation of its tegumental spines, the distribution of sensory papillae and by severe folds of the tegument.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.58.2-58.2
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• 2018

Fossil groups of galaxies have characteristic features of a dominant central elliptical galaxy (${\Delta}M_{12}$ > 2 in $0.5R_{vir}$) embedded in highly relaxed X-ray halo, which indicates dynamically stable and evolved systems. These are thought as a final stage of the evolution of galaxy groups in the hierarchical structure formation scenario. However, the formation and evolution of fossil clusters are still unclear due to lack of detailed studies. Therefore, we perform a kinematic research of a known fossil cluster Abell 2261 (A2261 hereafter) using spectroscopic data of 589 galaxies in the A2261 field. Even though A2261 is known as a fossil cluster, previous studies found several unusual features such as quite high X-ray entropy for a stable cluster, and an elongated shape, which are not expected in standard fossil clusters. Using the caustic method, we identify cluster member galaxies and discover a second bright galaxy (${\Delta}M_{12}=1.68$) at ${\sim}1.5R_{vir}$. The presence of such a bright galaxy can break the current fossil state of cluster in the near future. In addition, with two independent substructure finding methods, we confirm that the previously detected elongated galaxy distribution of the cluster is a real feature. These findings indicate that A2261 is not in a fully stable state, unlike the existing fossil definition diagnostic. We require a more stringent criterion for the fossil definition to represent a genuinely final stage of cluster evolution.

• Journal of Korean Society of Forest Science
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• v.98 no.6
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• pp.719-725
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• 2009

This study was conducted to establish the optimal condition for acclimatization from somatic embryos of Eleutherococcus seoulensis. Torpedo-shaped embryos of Eleutherococcus seoulensis were cultured on 1/3 MS and WPM media supplemented with $GA_3$ (3.0, 5.0 mg/L) for 4 weeks. Plentlets were transferred to 1/2 SH solid medium with 1.0 mg/L $GA_3$ and 0.2% activated charcoal for shoot and root elongation and them elongated plantlets further developed on 1/2 SH medium for 4 weeks. Developed plantlets further elongated into well-shaped leaf and root system on 1/3 SH medium under ventilation condition for 4 weeks. Plantlets grew normally on 1/3 SH basal medium, were acclimated on various soil. Survival frequency of plantlets was influenced by soil type(peatmoss+perlite, perlite, soil on Nam mountain). The highest survival rate to soil was more than 70% when plantlets were 1/3 SH medium under ventilation condition in Nam mountain soil. These results indicate that the systematic procedure of plant production in Eleutherococcus seoulensis could be practically applicable for mass propagation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.5
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• pp.471-479
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• 2010

The adiabatic two-phase flow in single rectangular microchannels was studied for different aspect ratios. The working fluids were liquid water and nitrogen gas. The hydraulic diameters of the rectangular microchannels were 490, 322, and $143\;{\mu}m$, and the widths of the microchannels were around $500\;{\mu}m$. The two-phase flow pattern was visualized using a high-speed camera and a long-distance microscope. This study was focused on bubble flow regimes. From the visualized images, the bubble velocity, bubble length, number of bubbles, and void fraction were evaluated. Further, the pressure drop in a single bubble was evaluated by using a unit cell model. The bubble velocity is proportional to the superficial velocity. Further, the relationship between the void fraction and the volumetric quality is linear. The pressure drop in a single elongated bubble is strongly related to the aspect ratio. Finally, the new correlation about the pressure drop of a single elongated bubble in the rectangular microchannel was proposed.

• Plant Biotechnology Reports
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• v.4 no.4
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• pp.321-328
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• 2010

An efficient protocol for in vitro organogenesis was achieved from callus-derived immature and mature leaf explants of Momordica charantia, a very important vegetable and medicinal plant. Calluses were induced from immature leaf explants excised from in vitro (15-day-old seedlings) mature leaf explants of vivo plants (45 days old). The explants were grown on Murashige and Skoog (MS) medium with Gamborg (B5) vitamins containing 30 g $1^{-1}$ sucrose, 2.2 g $1^{-1}$ Gelrite, and 7.7 lM naphthalene acetic acid (NAA) with 2.2 ${\mu}M$ thidiazuron (TDZ). Regeneration of adventitious shoots from callus (30-40 shoots per explant) was achieved on MS medium containing 5.5 ${\mu}M$ TDZ, 2.2 ${\mu}M$ NAA, and 3.3 ${\mu}M$ silver nitrate ($AgNO_3$). The shoots (1.0 cm length) were excised from callus and elongated in MS medium fortified with 3.5 ${\mu}M$ gibberellic acid ($GA_3$). The elongated shoots were rooted in MS medium supplemented with 4.0 ${\mu}M$ indole 3-butyric acid (IBA). Rooted plants were acclimatized in the greenhouse and subsequently established in soil with a survival rate of 90%. This protocol yielded an average of 40 plants per leaf explant with a culture period of 98 days.

• Korean Journal of Plant Tissue Culture
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• v.24 no.6
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• pp.351-355
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• 1997

Adventitious shoots were induced from cambial tissue cultures of 3-year-old seedlings using BLG mineral salts medium supplemented with 10 mM glutamine and 30 mM sucrose. The optimum growth regulator level for bud induction was 4,5 $\mu$M BA which produced average 25.5 shoots per cambium segment. Induced buds were elongated on GD medium supplemented with 30 mM sucrose followed by LMG medium supplemented with 30 mM sucrose for further shoot elongation. Elongated shoots were rooted on half-strength GD medium containing $0.54 ;\mu\textrm{M}$ NAA with the frequency of 20%. This system proved the high morphogenic potential of cambial tissue in larch.

• Journal of the Korean Society for Heat Treatment
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• v.23 no.4
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• pp.191-197
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• 2010

Zr addition is known as effective method to improve the anisotropy of steel due to the elongated MnS inclusions which are observed in hot forged steels. The aim of this research is to investigate the effect of Zr addition on the mechanical properties and manganese sulphide morphology of 0.27%C-Cr-Mo plastic mold steel. The ingots were prepared by vacuum induction melting and forged to ${\Phi}35mm$ round bar. Forged bars were quenched and tempered at $560{\sim}640^{\circ}C$ for 1 hour. Jominy test, microstructual observation, tensile test and Charpy impact test were conducted. The morphology of MnS inclusions was changed by Zr addition. The shape of MnS inclusions was not so much lengthened and controlled not to be elongated by Zr inclusions which surround the MnS inclusions. Tensile strength and yield strength of the tempered steels were not nearly affected by the addition of Zr, but elongation and reduction of area were decreased. Especially, the toughness of Zr added steels was deteriorated with increasing of Zr content. From the results of this study, it is assumed that anisotropy of steels was improved by the addition of Zr. However, impact toughness of the steel was significantly decreased by the excessive Zr addition (over 0.066%).