• Korean Journal of Poultry Science
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• v.48 no.2
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• pp.91-100
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• 2021

The study determined the effects of stock density (SD) and energy level (EL) on growth performance, serum biochemistry, and meat quality in Korean native chickens. A total of 240 chickens were randomly assigned to one of the four treatments including two stock density (low, 14, and high, 16 chickens per m²) and two energy level (low, 2,950, 3,000, 3050 ME kcal/kg, and high 3,150, 3,200, 3,250 ME kcal/kg, for starter, grower, and finisher, respectively). During the whole period of the experiment, the chickens were fed ad libitum. The greater final body weight and weight gain were achieved in chickens fed high energy diet, whereas the final body weight and weight gain were significantly reduced in high-density treatment compared with the low density. Chickens in low-density groups had a higher feed intake compared with high-density treatment, however, the energy level did not affect the feed intake. An improved overall feed conversion ratio was detected in the high energy treatment. There was a significant interaction between stock density and energy level on cholesterol concentration. The concentration of aspartate transaminase in serum was increased by higher stock density. There was a significant treatment interaction on IgM levels. Moreover, the carcass rate was significantly increased in the high energy level treatment. Based on the findings, we suggest that rearing chickens in low density with high dietary energy levels could be beneficial by improving the growth performance.

• Korean Journal of Environmental Biology
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• v.40 no.2
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• pp.187-198
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• 2022

In this study, Telenomus remus Nixon (Hymenoptera: Scelionidae) was first reported as a natural enemy of the fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) egg collected from corn fields in Korea, and its biological characteristics was studied. Based on morphological and molecular analysis, the parasitoid emerged from S. frugiperda eggs was identified as T. remus. We found that T. remus can attack the eggs of S. frugiperda, Spodoptera litra and Spodoptera exigua under a laboratory condition. The longevity of T. remus female adult was longer than that of male adult. The egg-to-adult period of T. remus was not affected by the host age and sex. T. remus female adult laid at least 1-3 eggs a day to a maximum of 37 or more eggs, and the most oviposited on the 3^rd to 4^th day after emergence. The host preference for oviposition of T. remus adult was high in the order of S. litura>S. exigua>S. frugiperda. T. remus preferred to parasitize 1- and 2-day-old host egg rather than 3-day-old host egg. When compared to the sex ratio of T. remus progeny, the rate of female progeny was higher at the initiation time of oviposition, while the proportion of male progeny increased significantly with female adult age, especially after 8-day-old adult. This information may be useful for improving T. remus mass rearing system and developing a biological control program to control S. frugiperda.

• 한국노년학
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• v.29 no.1
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• pp.329-352
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• 2009

This study examined life in old age and images of the aged perceived by middle-aged and old-aged generations through indepth interviews with 30 persons aged 40s through 80s residing in three areas (city or county) in capital region in Korea to use it as basic information in planning social welfare policy and reorganizing social services in response to population aging in capital region in Korea. In terms of economic life of the middle-aged and olde-aged generations perceived older people's opportunities for work were rarely given to the aged due to ageism and negative stereotypes of aging and the aged, and the aged tended to regard themselves less able or unable to work. In terms of social life of the aged both middle-aged and old-aged generations perceived that the frequency of social participation was low, and the daily life of the aged was found mostly aimless, unorganized and unplanned. In terms of psycho-social life of the aged both generations still felt that they were not alienated from the family, neighbors, and the society. In terms of social welfare services both generations thought the aged needed basic services such as income maintenance, health care, housing services, and particularly they felt lack of social services. The old-aged generation was willing to travel to the distance taking more than one hour to receive social services that they would need. Both the middle-aged and the old-aged agreed upon the necessity of preparation for old age and the benefits of earlier preparation, however, they said that they could not prepare for their old age due to lack of social programs to help preparation for old age and due to spending for rearing and education of their children. In terms of perceived life in old age both middle-aged and old-aged generations tended to be slightly positive, but the degree of positiveness differed between respondents from urban area and those from rural area regardless of generations. Images of the aged were perceived to be overwhelmingly negative while positive images were very few in number regardless of generations. This finding may suggests that negative stereotypes on aging and the aged are also prevalent in Korean society like in Western societies. Based on findings of this study some implications for social policies in response to population aging in capital region were suggested.

• Journal of the Korean Society of International Agriculture
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• v.23 no.5
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• pp.520-530
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• 2011

This study was carried out to evaluate the possibility of rice double cropping in Korea by assessing the growth and yield performance of rice cultivars transplanted at the extremely-early date. When the transplanted rice seedling was exposed to low temperature below 0℃, the survival rate decreased drastically. However, short exposure to below 0℃ one or two times did not damage transplanted rice seedling so severely. Thus, the earliest transplanting in spring would be possible when minimum temperature rises above 0℃. Compared with the conventional seedling nursery tray (CSNT), seedling rearing with the potted nursery tray was more effective for increasing leaf age and seedling dry weight during nursery period. In the first rice cropping, rice cultivation with seedlings reared in PSNT showed shorter growth duration and cumulative temperature from transplanting to heading than that with seedlings reared in CSNT. The earliest heading date on July 4 in Jinbuolbyeo was earlier by two to three days than that of Dunaebyeo. If rice has not exposed to cold damage, the earliest heading date of Jinbujolbyeo can advance to June 30 or July 1. In this case, rice harvest would be possible on August 5, enabling the rice transplanting of the second rice cropping before August 10. At transplanting time with low temperature damage rice yield were less than 400 kg/10a while rice yield exceeded 400 kg/10a at transplanting time without low temperature damage.

• Korean Journal of Culture and Social Issue
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• v.23 no.2
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• pp.295-332
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• 2017

The main purpose of this research is to analyze stress, social support and coping behavior of adults based on their level of self-efficacy. A total of 899 adults (399 male; 500 female), each with a child attending either elementary and secondary school, participated in the study. The inter-rater reliability for the open-ended questionnaire utilized in the study was 93.4%, with a Kappa coefficient of .92. The range of Cronbach α for the variables measured through a quantitative method was .87~.92. The results were as follows: First, the representative responses to the question about their most painful stress experiences were, financial difficulties, child rearing and duties of workplace. The Lower Efficacy group, compared to the Upper Efficacy group, responded much more with financial difficulties related responses. There were significant differences in the level of stress symptoms according to level of self-efficacy. The Lower Efficacy group expressed stronger levels of stress symptoms when compared to the Upper Efficacy group. Second, in terms of social support, the participants responded that they received the most help from their family members, followed by none(self), and friends. When comparing the two efficacy groups, the Upper Efficacy group responded most frequently that they received social support from their family members, whereas the Lower Efficacy group indicated none. There were significant differences in the level of relational conflicts according to the level of self-efficacy. The Upper Efficacy group showed much less conflict in parent-child relations, spousal relations and relations with their boss, compared to the Lower Efficacy group. Third, for the type of social support participants received, the most frequent response was emotional support, followed by none, and advice. Relatively, when comparing the two groups with each other, the Lower Efficacy group responded more frequently with none, whereas for the Upper Efficacy group responded more frequently with advice. There were significant differences in the amount of emotional support received according to level of self-efficacy. The Upper Efficacy group received much more emotional support from their spouses and their bosses compared to the Lower Efficacy group. Fourth, the most frequently adopted coping style to stress was self-regulation, followed by direct problem solving, and nothing(none). The most frequent response for the Upper Efficacy group was direct problem solving, whereas for the Lower Efficacy group was nothing(none). There was a significant difference in coping efficiency to stress according to level of self-efficacy. The Upper Efficacy group coped more efficiently with stress than the Lower Efficacy group.

• Journal of Marine Life Science
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• v.8 no.2
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• pp.166-177
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• 2023

The giant freshwater prawn (Macrobrachium rosenbergii) suffers economic losses in aquaculture facilities due to problems such as poor body color and carapace weakness. While this species is farmed on an animal-based diet, in the wild it consumes a detritus diet with a high proportion of plant matter. The plant matter they consume in the wild is not only a source of basic nutrients, but also carotenoids, which are responsible for body color. Korean goldenbell (Forsythia koreana) is a flowering tree widely distributed in Korea, and its leaves contain carotenoids comparable to yellow carrots. In this study, we investigated the effects of feeding Forsythia leaves to M. rosenbergii on their body color and health. The experimental diets were 100% commercial feed (control), CON, 80% commercial feed plus 20% Forsythia leaf powder, FP, and 80% commercial feed plus 20% unprocessed Forsythia leaves, FL, and each diet was fed to juvenile prawn with an average weight of 1.1 ± 0.2 g for 10 weeks. In terms of body color, the CON prawn were consistently clear ivory in color, while the FP and FL prawn changed from blue to dark brown as the days of rearing progressed. Survival and growth were not significantly different between CON and FP or FL. Histological comparison of the hepatopancreas revealed that the vacuole size of B cells, the constituent cells of the hepatopancreatic tubule, was significantly larger in FP and FL compared to CON. The vacuoles of B cells are responsible for the absorption and digestion of nutrients, suggesting that the supply of Forsythia leaves may have had a positive effect on the health of the M. rosenbergii. The above results show that the use of Forsythia leaves in the aquaculture of M. rosenbergii can be expected to improve body color and health without inhibiting growth.

• Korean Journal of Culture and Social Issue
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• v.11 no.1
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• pp.109-142
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• 2005

This paper examines the changes in family values in Korea by examining values of children, socialization values, and social support of elderly parents with young and olders mothers. A total of 314 mothers of infants (young mothers) and 395 mothers of adolescents (older mothers) completed a questionnaire compiled by Schwarz, Chakkarath, Trommsdorff, Schwenk and Nauck(2001) comprising of values of children, cultural values, socialization values, interpersonal relationship, social support, stress, and life-satisfaction. In terms of values of children, the older mothers are more likely to emphasize social values, such as continuing the family line. Young mothers are more likely to emphasize psychological values, such as the pleasure of seeing a child grow. As for reasons for net wanting to have children, young mothers are more likely to point out personal constraints than older mothers, such as restriction of freedom. Second, older mothers are more likely than young mothers to express willingness to provide support for their children and even when their children become adults. Older mothers had a more lenient expectation of their children in terms developmental timetable and to expect support from their children when compared with young mothers. Young mothers are more likely to socialize their children with greater warmth and at the same time have higher child-rearing stress when compared to older mothers. Third, when compared with older mothers, young mothers are more likely to receive practical and emotional support from their parents. On the other hand, older mothers are more likely to provide greater practical and emotional support to their parents than the young mothers. Overall, compared to young mothers, older mothers are more likely to hold traditional and conservative values of children and socialization values. These contrasting values reflect the changes in family structure and social change that have been progressing rapidly in recent years.

• Korean Journal of Ichthyology
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• v.35 no.4
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• pp.263-269
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• 2023

This study aims to contribute to the research on resource recovery for the rapidly declining population of Liparis tanakae by observing the larval development process and the morphology of juveniles based on their growth. Natural spawning eggs collected in Yeosu were used for observing the process of egg development and larval morphology. The water temperature during the rearing process was maintained at 12.3~13.5℃ (average 12.7℃). The fertilized eggs had an egg diameter ranging from 1.57 to 1.79 mm (average 1.71 mm) and were spherical and adhesive. Within 4 hours 35 minutes after fertilization, they reached the two-cell stage, and after 74 hours 10 minutes, the formation of the yolk sac began. At 106 hours post-fertilization, a caudal fin appeared at the tail tip. Hatching began at 526 hours, and the larvae developed with the yolk sac positioned just behind the eyes. The newly hatched larvae had both the mouth and anus open. Melanophores appeared inside the lower jaw and around the tail on the third day after hatching. By the 16th day after hatching, most of the yolk was absorbed, and melanophores were visible in the head region. Finally, on the 63rd day after hatching, the head region significantly developed, and the body shape and mouth were similar to those of an adult fish, signifying the transition to the juvenile stage. This study will serve as valuable data for aquaculture techniques related to the conservation and restoration of fish species based on the hatching and juvenile morphology of Liparis tanakae.

• Journal of Sericultural and Entomological Science
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• v.27 no.2
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• pp.7-19
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• 1985

The genetic variances and combinding ability of some useful characters were analyzd on sixty four combinations in the 8$\times$8 diallel cross using the four Japanese races(Jam 107, Jam 113, Jam 117 and Jam 119) and the four Chinese races(Jam 108, Jam 114, Jam 118 and Jam 120). The eight quantitative characters were the total larval stage period(TP), the fifth larval instar period(FP), the female cocoon total weight(FW), the male cocoon total weight(MW), the female cocoon layer weight(FL), the male cocoon layer weight(ML), the female cocoon layer ratio(FR), and the male cocoon layer ratio(MR). The results were as follows: The analysis of the genetic variance and the combining ability in the TP and the FP. In TP and FP, h2N was less than h2B. The GCA, SCA and RCA were at a high significant level. Hl/D and (Hl/D)1/2 ere large. The heterosis were small minus. E and D were large. The r was in the positive direction, because the recessive genes were mainly expressed as a short rearing periods. The regressions of the characters were passed below 0 point, because the characters in the TP and the FP were appeared overdominant. The order of the dominance in the TP of the parents were in the order of Jam 119>Jam 113>Jam 117>Jam 108>Jam 120>Jam 114>Jam 107>Jam 118, and that in the FP of the parents were followed in the orders of Jam 117>Jam 113>Jam 108>Jam 114>Jam 119>Jam 107>Jam 120>Jam 118. The analysis of the genetic variance and the combining ability of the FW and the MW. In the FW and the Mw, h2N was less the h2B. The GCA and SCA were large but RCA was little. Hl/D and (Hl/D)1/2 in the parents were large. Heterosis was large. E was appeared large in the FW, and small in the MW. D was small. The r was of the minus direction, because the dominance genes were less expressed. The regression of the these characters were padded below 0 point, because the characters in FW and MW were appeared overdominant. The orders of the dominance in the FW of the parents were as the order of Jam 107>Jam 108>Jam 119>Jam 113>Jam 114>Jam 120>Jam 117>Jam 118, and in the MW of them in the order of Jam 114>Jam 120>Jam 108>Jam 113>Jam 107>Jam 119>Jam 117>Jam 118. The analysis of the genetic variance and the combining ability of the FL and ML. In the FL and the ML, h2N was less than h2B. GCA and SCA were large. RCA was little. Hl/D and (Hl/D)1/2 ere large. Heterosis was large. The r was in the negative direction, because the dominance genes were less expressed. The regression of the characters of FL and ML were appeared overdominant. The dominance in the FL of parents ere in the order of Jam 120>Jam 114>Jam 119>Jam 119>Jam 118>Jam 107>Jam 117>Jam 113, and the ML of them in the order of Jam 114>Jam 108>Jam 120>Jam 117>Jam 118>Jam 107>Jam 119>Jam 113. The analysis of the genetic variance and combining ability of the FR and the MR. In the FR and the Mr, h2N was less than h2B. GCA was large. The SCA and RCA were little. In the FW, Hl/D was large but (Hl/D)1/2 was a little. In MR, Hl/D and (Hl/D)1/2 both were a littel. Heterosis was a little. E in the FR was in the negative direction, because the dominance genes were less expressed but that in the MR was the positive direction because the recessive genes were mainly expressed. The order of the dominance in the FR of the parents were in the order of Jam 117>Jam 114>Jam 108>Jam 120>Jam 118>Jam 119>Jam 107>Jam 113 and that in the MR these were in the order of Jam 114>Jam 117>Jam 108>Jam 118>Jam 107>Jam 119>Jam 120.

• Journal of Sericultural and Entomological Science
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• v.15 no.2
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• pp.21-28
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• 1973

This report is prepared to promote cocoon natures for the use of silk reeling material. It is easily understandable that there must be disuniformity composed with superior group and inferior group in commercial silkworms. If such different groups be seperated by some method, it would be a great contribution for the cocoon production. For a comparative purpose, silkworm sex seperation carried out because male silkworms produce more silk than female worms. The author has developed a new chemical reagent available for the seperation of superior group and inferior group from commercial silkworms, which he has named it as Better Hybrid Controller (BHC). The obtained comparative results are summarized as followings. 1. Basic investigation of BHC application a) In case BHC applied with hybrid worms and pure line, the former one starts to adapt mulberry leaves earlyer than pure line variety. b) The mulberry adapting interval distribution of pure line worms after BHC application showed U type distribution, but hybrid worms showed L type or Poisson's distribution. c) In case of BHC application with silkworms, the longer period application is, the duller distribution was formed. d) When silkworms are seperated in two groups by use of BHC application, the earlyer mulberry adapted group is seemed as stronger than the other part and the group ratio is 2 : 1. 2. Comparation between sex seperation result and better hydrid control (BHC) seperation result. a) The cocoon shell per cent of male worm group showed betweer result than the female group but only 0.4% difference between sexes. b) The cocoon shell per cent of superior group, seperated by BHC, showed 0.7% more than the inferior group. c) The average cocoon shell per cent of BHC treated cocoons showed much more than the Control group as 1.6∼2.4% increase. Enven the inferior group showed better result than the Control. d) Such unexpected result is considered to be the result that BHC application is activating some thing with silkworm physiology. e) On the ether hand, the result of sexes seperated groups or male worm group did not show desirable conclusion as far as cocoon shell per cent is concerned. f) However, when the male group was reeled as silk, it showed much better silk yield or silk per cent of cocoon than the female group as much as one per cent difference between by sexes. Such result was brought by superior silk yield from cocoon shell as much as 87.4%. g) On the other hand, the male group showed lowest non breaking reelable ratio (63%) among all group comparation. h) When we compare cocoon qualities by sex seperation and BHC seperation against the Control, there is no qualitative change, but BHC group showed quantitative promotion with cocoon bave length as much as about hundred meters. i) In case of calculation for productive income of cocoon production, BHC applied group showed about ten per cent income promotion more than the Control. The sexes seperated group, however, showed rather negative result because the male cocoon produced poor weight per box eggs which could not cover it by the inclose of silk yield of it. j) So, the BHC application with the fetched worm stage brought about big promotion for cocoon production. k) BHC method may be used either for seperation purpose or quantitative promotion with whole silk-worms. 3. Only male silkworms rearing did not show desirable productivity, so there is no reason to work out it in the fetching stage of worm.