• Korean Journal of Ichthyology
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• v.21 no.2
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• pp.81-86
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• 2009

The spermiogenesis and mature spermatozoa of Pseudobagrus fulvidraco were described by means of scanning and transmission electron microscopy. Spermiogenesis is characterized by lateral development of the flagellum, nuclear rotation, deep nuclear fossa formation and compaction into thick granules. The spermatozoa exhibit a round head containing a nucleus that lacks an acrosome, and having a midpiece and a flagellum. The midpiece is small and has a short cytoplasm including several mitochondria separated from the tail by the cytoplasmic canal. The flagellum contains the 9+2 classical axoneme structure and has two axonemal fins. The presence of axonemal fins in the flagellum is a common character in Bagridae. The interrelationships among the Bagridae as well as other teleosts are herein discussed.

• Development and Reproduction
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• v.22 no.4
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• pp.361-367
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• 2018

The newborn, Hippocampus kuda larvae were 6.97-8.81, standard length (SL) mm (mean 7.89 mm) and mouth and anuse were open. Dorsal fin rays 15-18 and pectoral fin-rays were counted 8 and had 10-11+21 myotomes, body's bony plate ring being developed strongly in the central axis of myotomes part. 4 days after bearing, the SL was 7.02-9.47 mm (mean 8.24 mm) and nostrils began to open. 12 days after bearing, larvae attained to 8.91-11.2 SL mm (mean 10.0 mm). From this time, their unique predation habit appeared. 21 days bearing, larvae attained to 12.1-14.8 SL mm (mean 13.4 mm) the and thorn of back was enlarged among the plate formed around ring. 41 days bearing, seahorses attained to 17.1-17.8 SL mm (mean 17.4 mm) and the number of body's bony plate ring of the top of rings trunk was 11 and on the tail of them was 33-36, similar to figure of adult.

• Applied Microscopy
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• v.29 no.4
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• pp.427-435
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• 1999

Spermatogenesis and fine structure of the spermatozoon of the marbled sole, Limanda yokohamae were examined by means of the scanning and transmission electron microscopy. The process of spermatogenesis of the marbled tole is similar to that of other teleost with external fertilization. During the spermiogenesis, chromatin that has been became fine]y granular progressively condenses into many large globules and that homogeneously condensed in the spermatozoan head. A spermatozoon consists of head and tail, and the acrosome is absent. The cytoplasmic collar contained eight mitochondria is observed in the posterior part of the head. The well -developed axonemal lateral fins are observed in the tail. In the TEM observation, the cross section of the axial filament shows '9+2' axonemal structure of microtubules, and the numerous vesicles are observed in the cytoplasm.

• Korean Journal of Ichthyology
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• v.19 no.1
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• pp.57-65
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• 2007

A new species of the rajid genus Okamejei is described from a single specimen (295 mm TL) from off Shantou, Gwangdong in the South China Sea. The new species differs from all other congeners in the following combination of characters: snout pointed, dorsal head length 6.7 times interorbital width, tail moderately wide and long, its length 48.5% TL, interdorsal distance less than length of first dorsal fin base, postdorsal tail short as 5.8% TL, small evenly distributed dark brownish spots, without ocelli on dorsal surface of disc, pores of ampullae of Lorenzini on ventral surface distributed from snout tip to distal end of metapterygium, scapulocoracoid high, its height about 1.4 times rear corner height, trunk vertebrae 23, predorsal tail vertebrae 50 and pectoral fin radials 96.

• Korean Journal of Ichthyology
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• v.18 no.3
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• pp.193-201
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• 2006

We researched the reproductive ecology of pale chub, Zacco platypus that inhabits Gajeong-cheon and Wonju-cheon that are a tributary to the Han river. The nuptial organ was formed on the head part, the anal fin and the tail part in male, the change of nuptial color was outstanding. By their changing body shape, the anal fin was extended and body depth came to be high during the spawning season in both sexes. Territorial male of defending behavior were head butting, rotated fighting, parallel swimming, biting and expelling. After pale chub located himself from the upper of the female that was approached to the side parallelling with the female, male and female spawned digging sand with their anal fin by vibrating and any parental care of the eggs was not taken. The spawning interval and lasting time were relevant to individuals density of spawning ground.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.4
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• pp.411-418
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• 2011

As a fish way is a structure for fish migrating well toward upper stream due to breaking river flow by a dam or dammed pool, the specific fish's swimming ability is one of the main factors in making a plan and managing it. In addition, it also needs to understand the current field in fish road to evaluate its performance. This study is aimed to analyze the swimming patterns with current velocity changes using a Particle Imaging Velocimetry (PIV) in order to understand the swimming ability of silver fish (Plecoglossus altivelis) that is one of the fishes migrating through the fish way of Nakdong River, and to analyze the 2 dimensional current field near to silver fish at swimming momentum. The results showed that average values of tail beat frequencies for continuous swimming with current velocity were 2.8 Hz at 0.3 m/s, 3.2 Hz at 0.4 m/s, 3.8 Hz at 0.5 m/s, respectively. The wake would be produced by direction turning of fish's tail fin and its magnitude would be verified by the difference of pressure. The pressure turbulent flow produced by its tail beat would be made in both sides, and then, the magnitude of wake should be the source of moving direction. The swimming momentum will help to support the primary factor in making a suitable design for specific fish species migrating toward the district river.

• Wind and Structures
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• v.29 no.6
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• pp.457-469
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• 2019

In this paper, a numerical solution is presented for supersonic flutter analysis of cantilever non-symmetric functionally graded (FG) sandwich plates. The plate is considered to be composed of two different functionally graded face sheets and an isotropic homogeneous core made of ceramic. Based on the first order shear deformation theory (FSDT) and linear piston theory, the set of governing equations and boundary conditions are derived. Dimensionless form of the governing equations and boundary conditions are derived and solved numerically using generalized differential quadrature method (GDQM) and critical velocity and flutter frequencies are calculated. For various values of the yaw angle, effect of different parameters like aspect ratio, thickness of the plate, power law indices and thickness of the core on the flutter boundaries are investigated. Numerical examples show that wings and tail fins with larger length and shorter width are more stable in supersonic flights. It is concluded for FG sandwich plates made of Al-Al₂O₃ that increase in volume fraction of ceramic (Al₂O₃) increases aeroelastic stability of the plate. Presented study confirms that improvement of aeroelastic behavior and weight of wings and tail fins of aircrafts are not consistent items. It is shown that value of the critical yaw angle depends on aspect ratio of the plate and other parameters including thickness and variation of properties have no considerable effect on it. Results of this paper can be used in design and analysis of wing and tail fin of supersonic airplanes.

• The Journal of the Korea Contents Association
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• v.19 no.10
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• pp.21-31
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• 2019

With the development of the aviation industry, aircraft painting design also plays the role of transmitting the national image while conveying the individual image of the airline. The recognition and recognition of the national image can be obtained by building a national brand. As a result, more and more companies are using the national brand image of their own country or other countries to add value to the company. Objective: To better reflect the national brand recognition for the design of the tail fin in the future aircraft painting design. This paper mainly studies the correlation between the tail graphic elements of aircraft painting design and national brand recognition based on the tail graphics of the three major airline alliance members. Based on the prior research, the relevant hypotheses were proposed and the questionnaire was designed. Secondly, a questionnaire survey was conducted on the passengers using the aircraft, and the correlation analysis was performed on the data by the SPSS regression analysis method. Conclusion: Data analysis has a strong correlation.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.6
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• pp.796-807
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• 2009

The swimming abilities of aquatic-animals are of vital importance to their ecology. The relationship between outer shapes and the swimming ability has been focused just a few centuries ago by engineering community. Present paper surveys the recent studies of the aquatic-animals' swimming performance in the morphological point of view. Also an experimental study is performed in order to investigate the effect of the tail fin's shape on the propulsive performance. The result showed that the morphological study provided valuable data for exploring the secrets of the aquatic-animals' swimming performance.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.188-197
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• 2005

Square patterned jet grouting technique is the soil improvement method that shakes the special end monitor left and right like as tail fin and mixing the soil and cement paste after cutting the soil in square shape by injecting the cement paste from installed two nozzles. The structure shape by jet grouting technique can be constructed in various shapes and sizes like as square, circle, and sector form designed by an engineer. Also, it can be constructed without waste material and reduced a construction time of work economically. In this study, the applicability of Square Jet Grouting to reduce permeability is estimated by FEM analysis and in-situ test in many cases which are various coefficient of permeability and breadth of grouting structure.