• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.4
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• pp.408-417
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• 2019

This study was conducted to identify taxonomic differences in the characteristics of Rhodeus uyekii and Rhodeus ocellatus during their initial life history via an interspecific hybridization experiment. Hybrids were compared to their parent species, and the findings were used to inform developmental research in commercially useful aquarium fish. The hatching rates of the cross-bred eggs were 75.9% for cross UO (R. uyekii ♀${\times}$R. ocellatus♂) and 71.9% for cross OU (R. ocellatus♀${\times}$R. uyekii♂), which did not differ greatly from the hatching rates of the normal cross-bred group. Backcross experiments resulted in 100% egg mortality during development. Newly hatched larvae of the original hybrid crosses were similar to those of the maternal line, and the color of the egg yolk was similar to that of the paternal line; therefore, the respective traits of the interspecific parents were identifiable within the cross-bred offspring.

• Development and Reproduction
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• v.24 no.4
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• pp.307-316
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• 2020

The purpose of this study is to observe the early life history of Korean Lefua costata and use the result as basic taxonomic research data for balitorid fish. The fertilized eggs were light green color with completely circle shape and mean size was 1.21±0.06 mm (n=30). Immediately after hatching, the size of the larvae was 2.81±0.11 mm (n=5) in mean length, with egg yolk. On the 3rd day after hatching, the preflexion larvae had a mean length of 4.64±0.09 mm (n=5), and their mouth was opened to start feeding. On the 8th day after hatching, a mean length of the postflexion larvae was 9.43±0.46 mm (n=5), the distal part of the notochord was bent to 45°, and 16 fin rays were developed on the caudal fin. On the 31st day after hatching, a mean length of juveniles was 22.3±0.85 mm (n=5), and the number of fin rays was the same as that of adult fish with (iv8) dorsal fins and (iii8) anal fins.

• The Mathematical Education
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• v.45 no.4 s.115
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• pp.439-457
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• 2006

This research was to understand the features of mathematization and didactical phenomenology, in a way that was not a routine calculation of equation, rather a complete comprehension by the reinventing historical principles of the equation. To achieve the purpose of this study, one-mate middle school student participated in the study. Interview and observation were used for collecting data during the student's performance. The results of research were: First, the student understood the mathematical concepts from a real life and developed the abstract concepts from it, which were very intimately related with his life. Second, the skill and formula definition were accomplished with the accompanying predicted and consequently derived mathematical concepts. Third, through the approach of using the history of mathematics, he became more interested in what he was doing and took lessons with confidence. Forth, the student performed his learning based on the historical reinventing principle under the proper guidance of a teacher.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.1
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• pp.1-10
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• 1989

The stress history of a bridge is different depending on the characteristic of traffic flow. Because the flow is varied with vehicle type, weight and headway time etc., statistical analysis in bridges is necessary to estimate the history by traffic flow. By applying the statistical analyses in fracture mechanics, the remaining service life of the structure can be estimated. In this paper, 1)the statistical analysis of vehicle type, weight and headway time etc. to analysis randomness of traffic flow, 2)measuring and analysis of stress history of a real bridge, 3)reappearance of stress history by Monte-Carlo Simulation using constitution ratio of vehicle type, weight and headway time as probabilitic variable, 4)comparision of the calculated and modelled stress history, 5)calculation of reduction factor, 6)comparision of frequency of stress range depending on span length etc. were performed. From the results, the basic modelled stress history which is necessary for the method of estimation of the remaining service life of the structure could be suggested.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.4
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• pp.279-284
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• 2021

The dung beetle, Gymnopleurus mopsus (Coleoptera: Scarabaeidae), is one of endangered species in South Korea. It was last recorded in 1971. To restore this species, we introduced G. mopsus populations from eastern and southern regions of Mongolia in July 2019 and August 2019, respectively. One of the main tasks for the restoration of endangered insects is to develop breeding techniques to eventually incorporate these insects into the restoration system. In a series of laboratory experiments, we investigated effects of short-term hibernation periods on life-history traits of G. mopsus. Adult G. mopsus that had hibernated for 30, 60, and 90 days had lower survival rates than adults that had hibernated for 120 days. We also compared developmental time of these four experimental groups and found a significant difference in the egg - phase. However, the duration of hibernation did not affect the fecundity, brood-ball size, or body size of F1 adults. Follow-up studies are currently being conducted to further investigate the effect of a short-term hibernation period on population growth of G. mopsus under laboratory conditions.

• Korean Journal of Ichthyology
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• v.26 no.1
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• pp.17-24
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• 2014

The egg development and early life history of Acheilognathus majusculus which is Korean endemic species from Yeong river were observed under the controlled water temperature, $18.0{\pm}1.0^{\circ}C$. Fertilized eggs are opaque yellow in color and round oval shaped measuring 2.12 (2.08~2.18) mm in length and 1.86 (1.80~1.98) mm in breadth. The number of eggs averaged 72 (40~112) per an oviposition. The eggs of this species began to hatch about forty three hours after insemination and the total length of larvae was 4.23 mm mean. S form moving of larvae were not observed during larval development. The larvae reached at the heterotrophic stage about twenty-five days after hatching. It is estimated that the larvae was comming out from freshwater bivalve since that time in nature. A. majusculus was grew up to be adult stage enough which can be join to new production for three hundred days after hatching with over 67.8 mm in total length.

• Korean Journal of Ichthyology
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• v.24 no.2
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• pp.101-109
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• 2012

The egg development and early life history of Acheilognathus macropterus from Japan which is an exotic bitterling from China were observed under the controlled water temperature, $20.0{\pm}1.0^{\circ}C$. Fertilized eggs are opaque yellow in color and long elliptic globe shaped measuring $2.78{\pm}0.12mm$ in length and $1.44{\pm}0.04mm$ in breadth. The number of egg averaged 151 per an oviposition. The eggs of this species began to hatch about seventy eight hours after insemination and the mean of total length of larvae were 3.8 mm. S form moving of larvae were observed from three days after hatching. The larvae reached at the heterotrophic stage about twenty-five days after hatching. Morphological character and analysis of cytochrome DNA of this species from Japan were relatively similar to Korean but spawned egg shape was different remarkably. Taxonomical research is necessary in the future.

• Korean Journal of Ichthyology
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• v.21 no.1
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• pp.15-22
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• 2009

An artificial breeding method was carried out to investigate development of eggs and the early life history of Iksookimia longicorpa. The eggs of the female were obtained by injecting gonadotropin (LHRH) and fertilizingby the dry method in the laboratory. The mature eggs were separate, demersal, light yellowish, and averaged $1.53{\pm}0.07mm$ in diameter. In water temperature of $23{\sim}25^{\circ}C$, the eggs hatched in 50~72 hours after fertilization, and their lengths reached $5.1{\pm}0.23mm$ in total length. On Day 4 after hatching, they averaged $7.1{\pm}0.47mm$ in total length and their yolk sacs were completely absorbed. From 25 days after hatching, they attained a juvenile stage reaching $12.8{\pm}0.49mm$ in total length. On the 100th dayafter hatching, their band patterns and external form were similar to those of adults, and they averaged $38.5{\pm}2.95mm$ in total length.

• Journal of the Korean housing association
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• v.20 no.4
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• pp.103-112
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• 2009

The purpose of this research was to find out the housing history of Sakhalin returnees in Ansan Gohyangmaeul since leaving hometown under the Japanese ruling period, who experienced two international migration for one's life. Face to face interview had been done with 20 returnees in the community center of Ansan Gohyangmaeul during October to December, 2008. The semi-structured questionnaire about housing the respondents lived in major life changes used to guide the individual interview. The results showed that personal life as well as housing histories were differed by the reason to move into Sakhalin, which still influenced the returnee' life up to now. The housing they had lived changed from barracks like a training camp, to Japanese small wooden cottage/row house, and then Russian brick house/ apartment. Housing alteration and addition and rebuilding were common to renew the old existing house. The boundary of residing area was mostly limited to the first residing location under soviet governing system throughout one's life without a long distance move. Housing satisfaction was very high in Gohyangmaeul because of the improvement of housing facilities and residence itself as well as the convenience of housing management, compared to former residence in Sakhalin. Economic and emotional aspects of life satisfaction were also high during about 8 years of living in the apartment. Forced movers still require the compensation on hand to either Korean or Japanese government no matter the amount. Social integration to the Korean community would be one of the main issues to new returnees as well as the already returned. In-depth interviews of case study need to reveal the unique housing experience of the forced mover according to the type of leaving hometown by oneself or by parents, and to returned region and time to motherland.

• 한국노년학
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• v.29 no.3
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• pp.1087-1105
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• 2009

This study is to look out the old Woman's decision that why they get divorced of the elderly and process of adaptation. So It provides them with practice intervention program. This study approach life history study of qualitative study. Data were collected from there three old women who have get divorced. Raw data were analyzed by Denzins analysis frame. According to research participant's marriage life were influence form patriarchal social system and they divorced for self-identity. But it was not an escape from patriarchal repression. The patriarchal repression from husband in context of family's level has extended to community. So At this study common theme of divorced elderly life that is "patriarchal based on culture system" and "break up life in cause by biased and oppression". The Author proposed self-helf group and intervention program for the divorced elderly women.