• Development and Reproduction
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• v.17 no.4
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• pp.337-343
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• 2013

Post-thawed larval rearing in Pacific oyster Crassostrea gigas was performed to investigate the survival rate with time course in three kinds of larvae cryopreserved. The highest survival rate and larval activity index (LAI) of post-thawed larvae were obtained from the permeation in 0.2 M sucrose and 2.0 M ethylene glycol (EG) at $-1^{\circ}C/min$ in freezing speed showing the survival rates just after thawing of 63.8% in trochophore, 84.1% in D-shaped veliger and 56.3% in early umbo veliger. In post-thawed larval rearing with food supply, the larvae lasted their lives until 24 hours in trochophore, 75 hours in D-shaped veliger and 57 hours in early umbo veliger. The results suggested that each larval stage post-thawed revealed no more further development to subsequent respective stage.

• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.1
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• pp.33-41
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• 2004

The type of trichomes, their density and pattern of distribution on leaves of 16 genotypes of mulberry, belonging to both diploid and polyploid categories, were studied by scanning electron microscope. The present investigation was undertaken to find out the relationship of physical attributes, especially the density and trichome types with higher acceptability and better rearing performance by the silkworm Bombyx-mori L. Two types of trichomes glandular and non-glandular types were observed on both the leaf surfaces of all the mulberry genotypes studied. In general, greater densities of trichomes were observed on the abaxial surface than the adaxial surface of leaves in most of the genotypes. Distribution of glandular trichomes were more in abaxial surface and non-glandular trichomes were more in adaxial surface. Overall, distribution of glandular and non-glandular trichomes per unit area of leaf did not follow any regular pattern. When leaves of those genotypes were fed to silkworms, trichome density was found to be significantly negatively correlated with the survival of larvae i.e., effective rate of rearing, but trichome density did not influence the economic characters of rearing. As the distribution of glandular trichomes (GT) and non-glandular trichomes (NGT) did not follow any definite pattern, no relation could be established between the GT and NGT densities with silkworm rearing performance. However, the ratio of GT and NGT in a particular genotype influenced the rearing parameters, higher the ratios better the rearing performance. High GT and NGT ratio (＞1.00) was found positively significant when correlated with economic parameters viz., larval weight, single cocoon weight and single shell weight. The study is useful in screening different mulberry genotypes for their better acceptability to silk-worm and higher rearing performance at the early stage of selection without actually conducting the rearing.

• Korean Journal of Human Ecology
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• v.12 no.5
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• pp.579-593
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• 2003

The purpose of this study was to investigate the social support, understanding of the children's problem in the female-headed single parents, and their child rearing methods. To obtain this purpose, in-depth interview was conducted to 8 female-headed single parents from March 3 to April 5, 2003. The contents of interviews were recorded and analyzed by qualitative method. The results were as follows: First, female-headed single parents were stuck for the social support and the relationships with parents-in-law were ruptured, especially. Secondly, female-headed single parents had well known about their children's daily life. Third, in the early stage of female-headed single parents, they had expressed the stresses in their hardship of life to their children, but it decreased whenever they were accustomed to their life.

• Development and Reproduction
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• v.24 no.3
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• pp.225-230
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• 2020

This study reports the presence of mature and bi-sexual phase gonads in red spotted grouper, Epinephelus akaara after less than a year of cultivation in a commercial indoor tank and a net cage. In December 2018, juveniles were placed in an indoor tank and cultured for five months. In June 2019, the fish were transferred to a net cage and cultured until September. The rearing temperatures ranged from 19.86℃-24.65℃ in the indoor tank and 21.86℃-27.65℃ in the net cage. During the net cage culture period, specimens were randomly selected for histological gonad examination. The highest gonadosomatic index (GSI) value was measured in July (3.38±2.53), and dramatically decreased in August (0.44±0.21) and September (0.42±0.30). In July, some mature fish showed signs of vitellogenic stage oocyte development (vitellogenic and oil droplet stage oocytes), but immature fish were in an early developmental stage containing peri-nucleolus stage (PNS) oocytes. Bi-sexual phase gonads containing spermatocytes and spermatids were observed in the lumen and several PNS oocytes. By August and September, most specimens showed early-stage ovary development. However, mature testis (in August) and bi-sexual phase gonads (in September) were also observed. These results provide evidence for early puberty and hermaphroditism in the red spotted grouper.

• Korean Parent-Child Health Journal
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• v.14 no.2
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• pp.76-83
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• 2011

Purpose: The purpose of this study is to compare the mother's rearing attitude and communication between mobile phone addiction group and non-addiction group in middle school students. Methods: A cross-sectional descriptive study was performed with 574 students from 3 middle schools (1 boy school, 1 girl school, 1 coeducation school) at G-city in Gangwon Province. The data was collected from the 10th to 24th of July in 2010. Statistical analysis of the results was carried out by means, frequencies, chi-square, t-test and multiple regression with SPSS/WIN 18.0 program. Results: There were significant differences in mobile phone addiction group and non-addiction group in regard to sex, school year, grades, mother' age, purpose of mobile phone use, activity after school, phone bill per month. Also There were significant differences in mother's rearing attitude and mother's communication between two groups. Conclusion: Mobile phone addiction among students is not serious, however, possibility of becoming an addict still remains. This study suggests that we have to educate them about proper mobile phone use in advance to prevent them from becoming a mobile phone addict in early stage. Therefore, we need to develop an educational program to prevent mobile phone addiction.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.1
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• pp.132-138
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• 2020

Marphysa sanguinea is the most well-known polychaete species with a high economic value. However, this species has a high mortality in the early rearing stage of aquaculture. This study was conducted to find out the optimal substrate size and organic contents for the growth and survival rate of M. sanguinea larvae and juveniles. It was observed that the smaller grain size (<Ø 0.063 mm) and high organic contents (5-10%) induced settlement and reduced settlement time of larvae. Moreover, the growth and survival rate of larvae reached high levels at Ø 0.004-0.016 mm of grain sizes and 5-7.5% of organic contents as advantageous substrates for settlement. The survival rate of juveniles reached over 90% in less than Ø 0.016 mm substrate on 15-day experiment for different grain sizes of substrates. These results indicated that substrate compositions of less than Ø 0.016 mm of sand size and 5-7.5% of organic contents in mud will enhance the productivity of M. sanguinea at the early stage.

• Journal of Korean Academy of Nursing
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• v.42 no.7
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• pp.1039-1049
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• 2012

Purpose: From the holistic environmental perspective, individual and environmental influences on low-income children's questionable development were identified and examined as to differences in the influences according to the child's developmental stage of infancy (age 0-35 months) or early childhood (age 36-71 months). Methods: This study was a cross-sectional comparative design using negative binominal regression analysis to identify predictors of questionable development separately for each developmental stage. The sample was comprised of 952 children (357 in infancy and 495 in early childhood) from low-income families in South Korea. Predictors included individual factors: child's age and gender; proximal environmental influences: family factors (family health conditions, primary caregiver, child-caregiver relationship, depression in primary caregiver) and institution factors (daycare enrollment, days per week in daycare); and distal environmental influences: income/resources factors (family income, personal resources and social resources); and community factors (perceived child-rearing environment). The outcome variable was questionable development. Results: Significant contributors to questionable development in the infancy group were age, family health conditions, and personal resources; in the early childhood group, significant contributors were gender, family health conditions, grandparent as a primary caregiver, child-caregiver relationships, daycare enrollment, and personal resources. Conclusion: Factors influencing children's questionable development may vary by developmental stage. It is important to consider differences in individual and environmental influences when developing targeted interventions to ensure that children attain their optimal developmental goals at each developmental stage. Understanding this may lead nursing professionals to design more effective preventive interventions for low-income children.

• Korean journal of applied entomology
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• v.53 no.3
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• pp.287-293
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• 2014

Matsumuraeses phaseoli is one of the main pests that attack the flowers and pods of red bean (Vigna angularis) and mungbean (Vigna radiata) in Korea. To elucidate the developmental characteristics and over-wintering stage of M. phaseoli, several stages of the insect were observed through artificial rearing under outdoor conditions in Suwon ($37^{\circ}$16'N $126^{\circ}$59'E 35ASL), Korea. In colonies in which neonate larvae were reared at about 2-week intervals for more than a year, the developmental period from larva to adult emergence became longer from spring to summer, but shorter from summer to autumn; aestivation was not observed during the summer season. The colony in which rearing started on Oct 8, 2008 over-wintered as pupae and emerged in late April next year with a survival rate of 6%. However, the colony in which the rearing started on Oct 23, 2008 over-wintered as mature larvae, pupated in late April, and emerged in early and mid-May with a survival rate of 2%. When the fifth instar larvae were transferred outside from the laboratory ($25^{\circ}C$, 15L:9D) between November and February, no larvae could survive during the winter season. Some newly laid eggs and newly emerged adults could not hatch and could not survive, respectively, in outdoor conditions in November and December. These results suggest that neonate larvae of M. phaseoli that hatch in October can over-winter as late larvae or pupae in Suwon, Korea.

• Journal of Sericultural and Entomological Science
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• v.6
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• pp.49-52
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• 1966

It has been reported that the effect of royal jelly on silkworms can be markedly resulted from feeding on royal jelly throughout all the instars. In 1965, I began the experiment in order to know whether it has a practical for rearing, only through feeding silkworms at 1st to 2nd instar, when a comparative little amount of mulberry leaves and labor is needed for rearing. In the method of my experiment, mulberry leaves with different concentration of royal jelly added, 2.5%, 5%, and 10%. respectively, are feeded on silkworms of Sulack ${\times}$ Soyang at 1st and 2nd instar in spring in 1965. However, in the result of the experiment there is not any effect on the survival. the growth speed, the body weight, of the larvae, and the weight of cocoon layer, the cocoon layer ratio, and number of silkworm eggs laid.

• Journal of the Korean Society of Tobacco Science
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• v.21 no.1
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• pp.17-25
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• 1999

To elucidate the effect of elevated sublethal temperature ($33\pm1^{\circ}C$) on polyamine metabolism and oogenesis, we investigated alterations in the major polyamines and ornithine decarboxylase (ODC) and arginine decarboxylase (ADC), and ovarian development during the pupal-adult development of the tobacco budworm, Helicoverpa assulta. Ovaries ODC activity under the elevated sublethal temperature ($33\pm1^{\circ}C$) were lower than those of the optimal rearing temperature ($25\pm1^{\circ}C$). whereas ovarian ADC activity was consistently higher than the optimal rearing temperature ($25\pm1^{\circ}C$). When the gonads were exposed to the higher temperature, ovarian putrescine showed somewhat suppressed levels throughout development, indicating a relatively high correlationship with the alteration aspects in ODC or ADC activity under elevated sublethal temperature. A somewhat precocious ovary was observed in an early stage of development at $33\pm1^{\circ}C$, but cellular abnormalities occurred in this ovary. The ovary developed under elevated sublethal temperature was observed the inhibitional effect of polyamine metabolism and the abnormal development of ovariole, which seem to be related to the sterility.