• Korean Journal of Ichthyology
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• v.12 no.3
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• pp.208-214
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• 2000

The egg development and morphological changes of larvae of the file fish, Thamnaconus modestus(Gunther), was investigated by artificial insemination. The fertilized egg was spherical in shape, colorless and adhesive with 0.63~0.67mm in diameter and yolk had 20~30 oil globules of various size (0.04~0.16 mm in diameter). The hatching occured at 53 hours after fertilization in $21.0\sim23.0^{\circ}C$ of water temperature. Hatched larvae measured 2.07~2.20 mm in total length with 5~6+17~18=22~24 myotomes. The 3~4 days after hatching larvae grew to the total length 2.62~2.77 mm, opened mouth and anus. The 5 days after hatching, total length of the larvae was 2.74~3.04 mm, the first dorsal fin was formed at the behind of head. After hatching 12~13 days larvae attained 3.78~3.99 mm in total length. This period formed rudimental dorsal fin and anal fin. Twenty days after hatching, larvae grew to 6.04~6.17mm in total length, at which time the dorsal, anal and caudal fin rays reached 19~20, 18~19 and 9~10, respectively.

• Korean Journal of Environment and Ecology
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• v.35 no.3
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• pp.285-293
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• 2021

This study was conducted to elucidate spawning period characteristics and early life development of eight barbel loach, Lefua costata (Balitoridae) at the Jusucheon stream, Okgye-myeon, Gangneung-si, Gangwon-do, Korea between January and December in 2018. The spawning period was estimated to be from May to August, considering the change in the gonad-somatic index, the appearance of young fry, and frequency distribution in egg diameter. It was a multi-spawning type. The gender ratio was 1:0.79 with 1,117 females and 879 males collected. The egg size was 0.24-0.93 mm, with mature and immature eggs found during the spawning period. The size of mature eggs was 0.71±0.02 mm, and the average number of fecundity was 1,786±818 (n=31). Observation of the egg development showed that the fertilized eggs were the sticky, gray, segregated, and demersal type with 0.76±0.03 mm in diameter. The hatching of the embryos began at about 34 hours (hatching rate 50%) after fertilization underwater temperature of 25℃. The average length of the newly hatched pre-larvae was 2.7±0.11 mm. The average length of pre-larvae at 4 days after hatching was 4.5±0.16 mm, and the yolk sac was completely absorbed and entered the post-larvae stage. At 20 days after hatching, the average length of post-larvae was 11.5±0.67 mm, and their fin rays were formed before they transitioned to the juvenile stage. At 100 days after hatching, the average length reached 49.8±2.60 mm, and the appearance and the lateral sideband patterns were similar to those of the adult fish.

• Parasites, Hosts and Diseases
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• v.50 no.1
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• pp.29-35
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• 2012

The aim of the study is to characterize the phenotypes of $CD4^+$ $CD25^+$ T regulatory cells within the liver granulomas and association with both Foxp-3 gene expression and splenic cytokines. Naive C57BL/6 mice were intravenously injected with multiple doses of the soluble egg antigen (SEA) 7 days before cercarial infection. The immunized and infected control groups were sacrificed 8 and 16 weeks post-infection (PI). Histopathology, parasitological parameters, splenic phenotypes for T regulatory cells, the FOXP-3 expression in hepatic granuloma using real-time PCR, and the associated splenic cytokines were studied. Histopathological examination of the liver revealed remarkable increase in degenerated ova within hepatic granuloma which decreased in diameter at weeks 8 and 16 PI ($P$<0.01). The percentage of T regulatory cells ($CD4^+$ $CD25^+$) increased significantly ($P$<0.01) in the immunized group compared to the infected control at weeks 8 and 16 PI. The FOXP-3 expression in hepatic granulomas increased from 10 at week 8 to 30 fold at week 16 PI in the infected control group. However, its expression in the immunized group showed an increase from 30 at week 8 to 70 fold at week 16 PI. The splenic cytokine levels of pro-inflammatory cytokines, IFN-${\gamma}$, IL-4, and TNF-${\alpha}$, showed significant decreases ($P$<0.05) compared to the infected control group. In conclusion, the magnitude and phenotype of the egg-induced effects on T helper responses were found to be controlled by a parallel response within the T regulatory population which provides protection in worm parasite-induced immunopathology.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.3
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• pp.287-295
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• 2017

Egg development and morphological change of larvae of the Sakhalin sole Limanda sakhalinensis were studied by observing specimens obtained in a rearing experiment from fertilized eggs to the juvenile stage. The wild broodstock was collected in January 2010 and kept in a circular water tank (${\O}1.5{\times}1m$) at a temperature of $14.5{\pm}0.5^{\circ}C$. Fertilized eggs ranged from 0.72 to 0.82 mm ($0.77{\pm}0.07mm$, $mean{\pm}SD$) in diameter. The eggs were spherical, transparent and adhesive demersal. The egg yolk was divided from the oocyte 10 min after fertilization (AF), and an embryo was formed in 36 h AF. More than 50% of the eggs hatched within 133 h AF. The mouth and anus did not open until $3.5{\pm}0.25mm$ total length (TL). At 4, days after hatching (AH), the fish became larvae 3.7 to 4.2 mm ($4.0{\pm}0.36mm\;TL$), yolk absorption was completed and the mouth began to open. The left eye moved upward and the nostril moved to the right at 39 days AH. These post-larvae ranged from 8.0 to 9.9 mm TL ($8.9{\pm}1.33mm\;TL$). At 50 days AH, the fish became juveniles ($12.4{\pm}1.20mm\;TL$) There were 70-72 dorsal fin rays, 55-56 anal fin rays, 11 pectoral fin rays, and 6 ventral fin rays and the juveniles adopted a benthic life.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.6
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• pp.485-491
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• 2004

Spawning induction, egg development and larval growth of ark shell (Tegillarca granosa) (L.) were investigated. The most effective method of spawning induction was steady temperature increasing from$4^{\circ}C\;to\;28^{\circ}C$ with irradiation of sea water by UV after T. granosa was exposed to air at $4^{\circ}C$ Optimum condition for larval roaring was under the 32.4 psu and two temperature $regimes:\;28{\pm}1^{\circ}C\;and \;25{\pm}1^{\circ}C$. Fertilized eggs was demersal isolated eggs, and egg diameter was $60{\mu}$. D-shaped larvae appear about 20 hr after hatching with $94.1{\mu}$ in shell length and $86.7{\mu}$ in shell height. Ten days were required from hatching to umbo larva stage, of a mean shell length $125.2{\mu}$. On 25th day, the larva grew to $450{\mu}$ in shell length and began to settle on the bottom. Effect of temperature between $25^{\circ}C$ (control group) and $28^{\circ}C$ on larval growth was not different. Survival rate of larvae settled on the bottom was about $19{\%}$ in both temperatures conditions $(25^{\circ}C\;and\;28^{\circ}C)$.

• Journal of Sericultural and Entomological Science
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• v.54 no.1_2
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• pp.17-22
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• 2016

Rearing environment direct effects on oviposition preference of black soldier fly(Hermetia illucens). In this study, the number of egg-filled flutes was surveyed according to the size of adult rearing cages and oviposition media of black soldier fly (BSF). The height of the adult rearing cages were fixed at 2 m and provided different sizes of width and length and released 20,000 BSF adults in the rearing cages. The mean number of BSF egg-filled flutes was 895.4 at $4{\times}4m$ cage, 876.3 at $2{\times}1m$ cage and 62.3 at $1{\times}1m$ cage. Comparison of egg-filled flutes was according to cages material of adult BSF. The mean number of egg-filled flutes were 820.7 and 604.3 at different cage materials such as mosquito net and green house film. The mean numbers of egg-filled flutes were 326.6 in green floral form, 135.2 in green corrugated cardboard and 41.0 in brown corrugated cardboard. And the mean number of egg-filled flutes were similar floral form with the corrugated cardboard was overlapped by floral form such as 57.7 and 64.7. The mean number of egg-filled flutes was 29.0 and 48.2 in 6 mm and 4 mm diameter of oviposition hole.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.4_2
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• pp.605-613
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• 2023

The multi-axis combined machining technology has enabled combined machining, which was difficult. However, the reality is that manufacturing costs are rising due to expensive equipment and there is a shortage of machine operation engineers. The purpose of this research is to present the optimum cutting conditions for the surface roughness when processing the inner diameter of SUS440C, which is an egg material, using a CNC automatic lathe. As a result of measuring the surface roughness, dry machining was the best at R_a0.481㎛ at a spindle speed of 4,000rpm, a feed rate of 0.05rev/min, and a cutting depth of 0.3mm. In wet machining, the highest value was R_a0.317 at a spindle speed of 2,000 rpm, a feed rate of 0.05 rev/min, and a cutting depth of 0.2 mm. The lower the feed rate, the better surface roughness appears. It was found that the feed rate had more influence than the number of revolutions and depth of cut.

• Applied Microscopy
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• v.41 no.3
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• pp.189-196
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• 2011

Histological study on egg envelope and oogenesis of Kichulchoia multifasciata (Pisces, Cobitidae) was carried out by light microscopes and scanning electron microscopes. Various developmental cells appeared in ovary of the specimen catched during November 2010. The cytoplasm of oogonia was acidic and many nucleoli were located at the inner side of nucleus membrane. The size of the oogonia was $103.9{\pm}24.7$ ${\mu}m$ with nucleus size $42.9{\pm}6.9$ (31.1~50.3) ${\mu}m$. Primary oocyte having $277.5{\pm}60.5$ (216.7~354.9) ${\mu}m$ in diameter began to accumulate yolk vesicles. As the developmental stages proceed, secondary oocyte grows larger to $617.6{\pm}85.1$ (503.4~723.6) ${\mu}m$, and eosinophilic yolk granules yolk granules appeared between the yolk vesicles occupying most cytoplasm, and there are some yolk mass formed already. There are some yolk mass formed already. Envelope of fertilized egg investigated by a scanning electron microscope had plenty of microvilli (2~3 ${\mu}m$ in length) over the entire egg surface and a micropyle. Especially, the microvilli surrounding the micropyle were longer than those of egg surface with $5.26{\pm}1.22$ ${\mu}m$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.1
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• pp.19-26
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• 2020

The maturity and spawning of pacific sand eels Ammodytes japonicus, was investigated using samples collected by gill net in coastal waters near Donghae, Gangwon-do, from January 2017 to December 2018. Monthly changes were analyzed in maturity stage, gonadosomatic index (GSI), egg diameter, fecundity (F), and total length (TL) at 50% group maturity. The average TLs of female and male A. japonicus were 18.5 and 18.1 cm, respectively. The spawning period was from November to March, with the peak from December to February based on monthly changes in GSI and maturity stages. The egg diameter during the spawning-capable stage was 300-1000 (main mode 500-600) ㎛. Fecundity ranged from 6,411 eggs at 16.7 cm fork length to 45,771 eggs at 24.7 cm fork length. The relationship between TL and F was F=0.00005TL^4.2715 (R²=0.7216), such that F increased with TL. TL at 50% group maturity was estimated to be 15.1 cm for both sexes.

• Journal of Korean Society of Forest Science
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• v.100 no.3
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• pp.397-401
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• 2011

This study was conducted to clarify the breeding ecology of tits Parus spp. used artificial nest boxes in a deciduous forest at the Ansung Campus, Chung-Ang University from March through July, 2006 to 2010. Varied tit Parus varius, marsh tit P. palustris and great tit P. major bred in artificial nest boxes during our study period. There were no differences in number of breeding bird pairs among different entrance diameters of artificial nest boxes. The number of breeding pairs of great tits was the most highest among tits and that of varied tits was the least. Great tits mainly used 40 mm and 35 mm artificial nest box entrance diameter and marsh tits preferred 30 mm entrance diameter. In three tits species, there were differences in first egg date, clutch size, brood size, egg incubation period, nestling care period and breeding success among study years. It is needed the study on long-term ecological research about breeding ecology of tits related with habitat conditions.