• 한국수산과학회지
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• 제40권1호
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• pp.16-23
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• 2007

Nonylphenol (NP) is an estrogen-mimicking compound or xenoestrogen. This study investigated the effects of nonylphenol on the reproductive status of the equilateral venus Gomphina veneriformis. The experiment lasted 24 weeks, Experimental groups consisted of a control and three nonylphenol exposures ($1.0,\;2.5,\;and\;5.0\;{\mu}g\;NP/L$). Mortality did not differ significantly between the control and the exposure groups. The sex ratio (F:M) was 1:1 in nature and 1:1.03 in the control group. However, it changed to 1:3.5 with $5.0\;{\mu}g\;NP/L$ exposure. Gonad maturity in females was higher in the nonylphenol exposure groups than in the control group. By contrast, in males, it was lower in the nonylphenol exposure groups. Intersex individuals constituted 0% in nature, 3.08% in the control group, and 23.6% in the group exposed to nonylphenol, with female characteristics more prevalent than male. As the concentration of nonylphenol increased, the accumulation of lipofuscin increased in the mid-gut gland.

• 한국수산과학회지
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• 제37권3호
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• pp.197-201
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• 2004

Juveniles of parrot fish (Oplegnathus fasciatus) were graded and divided into three groups (mean initial size): Small group $(32.9\pm3.2\;g),$ Large group $(130.1\pm12.3\;g)$ and Ungraded group $(74.8\pm29.8\;g).$ Growth and sex ratio were monitored over 3 years. It was concluded that no production advantage was gained by weight grading. There were no differences when the pooled data from the two graded groups were compared with the ungraded group, although mean weight and survival of the large group were continuously higher than those of other groups until the end of rearing period. The highest percentage of males was found in the large group. These results show that males start growing faster than females long before the size grading.

• 한국수산과학회지
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• 제36권2호
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• pp.144-150
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• 2003

Reproductive biology and population dynamics of Latreutes planirostris were investigated on the south western waters of Korea from June 2001 to May 2002. This paper describes sex ratio, population growth, and reproductive aspects of Latreutes planirostris. Brood size was an isometric function of female carapace length. Based on dry weight, reproduction effort (mass of eggs/mass of female) averaged 0.23. Ovarian examination showed that there was significantly higher gonadosomatic index from May to September, with a peak in June. Statistical analysis revealed that the ovarian dry weight of females with eyed eggs was significantly higher than that of those with non-eyed eggs. This suggests that females were potentially consecutive breeders. Sex ratio showed that female is more numerous than male. Growth parameters mortality and recruitment were estimated by monthly length-frequency data. Growth parameters were estimated, using the seasonalized von Bertalanffy growth function model $(L\infty\;=\;12.70\;mm\;CL,\;K\;=\;0.87yr^{-1},\;C\;=\;0.96,\;WP\;=\;0.59)$. The recruitment pattern was twice a year.

• 한국가축번식학회지
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• 제16권3호
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• pp.261-267
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• 1992

The reproductive performance of SPF ICR mice under single paired mating were examined to get reproductive background data and to establish single paired rotational mating system. The results obtained were as follows : average litter size was 15.4$\pm$2.0 heads ; average weaning rate was 95.7$\pm$4.9% ; sex ratio(male/female) was 1.09$\pm$0.26 ; aveage delivery interval was 23.0$\pm$2.4 days. It was given the largest litter size at the age of 121~150 days and in 2nd~4th parities, but at the age of under 90 days and in 1st parity weaning rate and delivery interval were higher and shorter than those of the other ages and parities, respectively. In sex ratio, the number of male litters was slightly increased from that of female litters. The weaning rate of litters from dams which nuresed 12 litters was the highest among those of different litter sizes, and it was decreased dependent upon increment of litter size. There were no difference among 4 groups for reproductive performance, therefore the present study could have important sources for animal breeders who produce mice using the single paired rotational mating system.

• 한국수산과학회지
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• 제36권6호
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• pp.646-653
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• 2003

Investigations were made on the population structure, sex ratio, growth, and recruitment patterns of Leptochela sydniensis in the southwestern coastal areas of Korea, between May 2000 and December 2001. Spawning period, fecundity, brood loss, reproductive output, and size at sexual maturity also were examined. The results of the sex ratio showed that females were more numerous than males during the overall study period. Parameters of growth were estimated using the modified von Bertalanffy growth function (VBGF) model incorporating seasonal variation into growth. Females grew somewhat faster and reached a larger size than males $(L\infty=12.80\;mm\;CL\;and\;K=0.70\;yr^{-1}\;or\;females,\and\;L\infty=12.08\;mm\;CL\;and\;K=0.69\;yr^{-1}$ for males). The structure of recruitment patterns obtained by the FiSAT program indicated one normally distributed group. Based on the occurrence of ovigerous females and the gonadosomatic index (GSI), the main spawning season was from June to August. Analysis of covariance indicated that brood loss was not observed during the incubation period. The size at which $50\%$ of females are mature is estimated as 5.48 mm CL.

• 한국양식학회지
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• 제22권1호
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• pp.16-22
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• 2009

한국산 가재 Cambaroides similis 자연 개체군의 생활사를 밝히기 위해 2006년 3월부터 10월까지 약 8개월간 서울소재 관악산에 서식하는 가재를 조사하였다. 조사기간 중 포획 및 재포획 방법을 사용하여 총 551개체에 대한 조사가 이루어 졌다. 연구결과 관악산의 가재 개체군은 체장 빈도 분포를 통해 4개의 연령 구조를 가지는 것으로 추정되며, 암수 성비는 거의 동일하였다. 성장률은 수은에 크게 영향을 받음을 알 수 있었다. 6월에 확인된 어린 유생들은 8월에 성체로 성장하였다. 논란이 있었던 한국산 가재의 교미시기는 늦은 가을부터 시작됨을 확인하였다.

• 한국양식학회지
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• 제19권2호
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• pp.99-108
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• 2006

Sex of the Nile tilapia Oreochromis niloticus is mainly determined by an XX/XY system. However, accumulating evidences suggest the existence of additional sex modifying factors including environmental, autosomal and parental influences. In order to investigate the possibility of parental effects on sex ratios of tilapia progenies, in this study, a series of crosses was carried out using gynogenetic clonal fish, neomales, normal males and females, and YY fish. Crosses between clonal XX male and clonal female have yielded only female progenies and no parental influences were observed. However, in the crosses between clonal males and normal females, female parents were significantly associated with the progeny sex ratios ($X^2$=20.046, 7 d.f., p<0.01). Progeny sex ratios from the crosses between neomales and normal females ($X^2$=60.491, 5 d.f and $X^2$=28.072, 2 d.f.) also showed significant association with female parents (P<0.001). The stability of progeny sex ratios from repeated spawns were confirmed by using 6 different parental pairs. In 16 crosses between normal males and normal females, sex ratios of progenies showed clear maternal influences, and further analysis of the results revealed a negative correlation ($r^2$=0.7718, p<0.05) between the sex ratios of progenies from two different males, indicating a strong paternal influence. No statistically significant relationship between survival rates and sex ratios of progenies was observed in any genotypic groups. Taken together, the influence of parental pairs on progeny sex ratios in this species is evident although the cause of this influence is not clear.

• 한국응용곤충학회지
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• 제39권2호
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• pp.105-110
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• 2000

사과, 복숭아와 밤 열매 등을 가해하는 주요해충 중의 하나인 복수아명나방(Dichocrcis punctiferalis)을 성페로몬을 이용하여 발생예찰하기 위해 성페로몬 성분분석과 행동관찰, 성페로몬 조성별 야외포획실험을 수행하였다. 처녀암컷의 교미행동은 16L:8D의 광주기 $26\pm$1$^{\circ}C$ 온도조건에서 소등 후 4시간째에, 수컷의 가는털뭉치 돌출행동은 5시간째에 최고를 나타내었다. 이시간대의 암컷 복부 끝 헥산추출물에서는 E10-hexadecenal과 Z10-hexadecenal이 가스크로마토그래피 분석에 의해 85:15의 비율로 검출되었다. 야외에서 수컷 성충을 유인하기 위해 두 성분의 합성화합물을 이용하여 사과 및 복수아와 밤 과수원에서 포획실험이 수행되었는데 E10-hexadecenal과 Z10-hexadecenal이 70:30~80:20의 비율에서 가장 많이 포획되었고, 이와 유사한 조성에서 수컷의 가는털뭉치 돌출반응과 상승비행반응이 관찰되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제32권1호
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• pp.137-143
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• 2019

Objective: The aim of this study was to compare male and female geese of two contrasting genotypes in terms of fatty acid composition, indexes related to human health, lipid metabolism and oxidative stability of the meat. Methods: The experiment was carried out on total of 120 geese of two different genotypes; the native breed Czech goose (CG) and commercial hybrid Novohradska goose (NG). One-d-old goslings were divided into 4 groups according to genotype and sex, and 8 birds from each group were slaughtered at 8 weeks of age. Results: The effects of the interactions between genotype and sex were observed on growth performance and carcass traits. Final body weight (p<0.001), daily weight gain (p<0.001), daily feed intake (p<0.001), slaughter weight (p<0.001), and cold carcass weight (p<0.001) were highest in NG males and lowest in CG females. The meat fatty acid composition results showed effects of both genotype and sex on the total n-6 and the total polyunsaturated fatty acid (PUFA) content, as well as the PUFA n-6/PUFA n-3 ratio. Regarding genotype, the total n-6, the total PUFA content and the PUFA n-6/PUFA n-3 ratio were higher in CG, and higher values were found in females. In terms of the lipid metabolism, ${\Delta}^5-{\Delta}^6$ desaturase (p = 0.006) was higher in males. The meat oxidative stability results revealed an interaction between genotype, sex and storage time (p<0.001). The highest (13.85 mg/kg) malondialdehyde content was measured in the meat of CG females after 5 days of storage and was presumably related to a higher PUFA content. Conclusion: NG had a relatively higher growth rate and meat oxidative stability, whereas the advantage of CG meat is its favourable fatty acid profile characterized by a higher PUFA content.

• 한국인구학
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• 제16권2호
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• pp.1-23
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• 1993

Korea fertility level has dropped since the 1960's and speed of decline has accelerated in the 1980's. In the resuls, the growth rate reached to less then 1 percent in 1990 and will be $\ulcorner$0 $\lrcorner$ percent growth in 2021. The total population will increase to 50, 586 thousand persons in 2021 then will decrease. With the rapid fertility decline the age structure of Korean population has changed : while the proportion of child population aged 0-14 is decreasing sharply, that of old-age population aged 65 and over is increasing. Because of the recent increase of sex ratio at birth, the sex structure among the young generation has been destorted; the sex ratio at age 0-4 was as high as high as 112.0 in 1990. The effects of these population phenomena on Korean society are the followings: 1) Old age dependency ratio is increasing rapidly and continuously and will be about 40.0 from the 2050's. 2) Because of the rapid decline of the number of births, the absolute number of the major labour force at age 25-34 will decrease after around 2000 and then from the 2010's become less than that in 1990. 3) Since the large fertility defferentials by womens's educational level have continued and the relation between the educational levels of mothers and children are very strong, level has dropped among higher educated women first when the average fertility level has declined in Korea, the average educational level of the children is may be expected to be relatively low and then the future productivity is will be also low, which causes the decline of 'quality of population. 4) When the high sex ratio at birth (over 110 since 1986) continues, number of brides will be short by over 20 percent from the 2010s, which will bring various kinds of social prblems. Therefore, the counter measures in concrete to relieve the heavy problems are recommended as follows: 1) The extention of the birth intervals, which helps to drop the population growth rate at the same level of number of children per women. 2) The positive supports for out-migrants, which helps to reduce the population size without any destortion of age-sex structure. 3) The defferent supports of family planning for the higher and lower classes, which helps to reduce the gaps between different ferility levels of the classes and to keep and improve the quality of population. 4)population education for both students and adults, which helps to minimize the gap between the private and public requirements.