• Title/Summary/Keyword: Population Growth Rate

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Aging Society and Labor Market (고령화 사회와 노동시장)

  • Jung, Cho-See
    • Journal of Digital Convergence
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    • v.10 no.1
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    • pp.185-194
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    • 2012
  • Population aging in Korea is in progress rapidly, though it isn't recognized as a critical situation now. Absolute scale of population will decrease since 2030 and that of 2050 will stay in 2005 levels. But most serious problem is that the core working age group, 25-54 ages will begin to decrease since 2012 because of low fertility and population aging. In these situation of population aging, we will face inevitably great amount of labor force shortages and we should build up policy alternatives for solving these problems. I proposed some policy alternatives. firstly, pronatalism policies including state-supported child-care system for preventing decreases of absolute scale of population. Second, facing up to labor shortages under population aging, I proposed policy alternatives for increasing labor market participation, measured by employmeny rate, of aged (or aging) people including wage-peak system of extending retiring ages and women including lowering opportunity costs of women labor market participation rates, given laboer forces. And to conclude, we should approach to the aging problems by steady state equilibrium ecnomic growth, under inevitable population aging.

Population Ecological Characteristics of the Soft-shelled Clam, Mya japonica in the Intertidal Zone of South Sea in Korea (한국 남해안 조간대에 서식하는 우럭, Mya japonica의 자원생태학적 특성)

  • 이선길;장창익
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.36 no.3
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    • pp.234-243
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    • 2000
  • This paper is to study population ecological characteristics, including growth parameters, survival rate, instantaneous coefficients of natural and fishing mortalities, and age at first capture of the soft-shelled clam, Mya japonioa in the intertidal zone of South Sea in Korea. For describing growth of the clam a von Bertalanffy growth model was adopted, The von Bertalanffy growth curve had an additive error structure and the growth parameters estimated from a non-linear regression were SH/sub ∞/=79.83mm, K=0.26, and t/sub 0/= -0.01. Survival rate (S) of the soft-shelled clam was 0.26 (SD=0.02). The instantaneous coefficients of natural mortality (M) was estimated to be 0.78/year and fishing mortality (F) 0.57/year for the soft-shelled clam. The age at first capture (t/sub c/) was estimated as 2.69 year. The mean densities of the soft-shelled clam by bottom type were 3.40 inds./m²(SE=0.18) in the sand, 63.4 inds./m²(SE= 0.53) in the muddy sand, and 0 inds./m2 (SE=0) in the gravelly sand. The mean densities of the soft-shelled clam by 3 different areas were 4.88 inds./m²(SE=0.09), 2.61 inds./m²(SE=0.13), 7.20 inds./m²(SE=0.18), respectively and the biomass of the clam were estimated as 131mt, 121mt, 665mt, respectively. An yield-per-recruit analysis showed that the current yield-per-recruit of about 8.30g with F=0.57/year and the age at first capture (t/sub c/) 2.69 year, was lower than the maximum possible yield-per-recruit of 9.60g. Fixing to at the current level and increased fishing intensity (F) could produce an increase in the predicted yield-per-recruit from 8.30g to about 9.40. However, estimated yield-per-recruit increased to 1.30g by decreasing to from the current age (2.69 year) to age two with F fixed at the current level. Yield-per-recruit was estimated under harvest strategies based on F/sub max/ and F/sub 0.1/.

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A Study on the Stock Assessment and Management Implications of the Hairtail, Trichiurus lepturus Linne in Korean Waters 1. Estimation of Population Ecological Characteristics of the Hairtail, Trichiurus lepturus Linne in Korean Waters (한국 연근해 갈치의 자원평가 및 관리방안 연구 1. 한국 연근해 갈치의 자원생태학적 특성치 추정)

  • ZHANG Chang-Ik
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.29 no.5
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    • pp.567-577
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    • 1996
  • This study is to estimate population ecological parameters, including growth parameters, survival rates, instantaneous coefficients of natural and fishing mortalities, and age at first capture, as well as growth rates at age of the hairtail, Trichiurus lepturus Linne in Korean waters. For describing the growth of the hairtail, three growth models were fitted, and the von Bertalanffy growth model was adopted for the purpose of the further stock assessment work. The von Bertalanffy growth parameters estimated from a nonlinear regression using EXCEL Solver were $L_\infty=46.01cm$, K=0.3868, and $t_0=-0.3220$. Annual survival rate (S) of the hairtail was estimated to be 0.277 (variance=0.00035) and the instantaneous coefficient of natural mortality (M) was estimated to be 0.441/year. Instantaneous coefficient of fishing mortality (F) for the recent years was calculated as 0.843/year, implying an impact from fishing about two times greater than that of natural mortality. The age at first capture $(t_c)$ was estimated to be 0.787 years, which is much younger age than $50\%$ mature age. Finally, the growth rates at age were estimated.

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Comparative Analysis of the Growth for Selectively Bred Korean Turbot Scophthalmus maximus Population (한국 육종터봇(Scophthalmus maximus)의 성장률 비교 분석)

  • Kim, Min Sung;Kim, Tae Hwan;Han, Jae Yong;Jo, Hyeon Kyeong;Kwak, Ju Ri;Park, Ji Been;Suh, Jong-pyo;Lee, Woo-jai
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.53 no.4
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    • pp.563-565
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    • 2020
  • Turbot Scophthalmus maximus can be cultured at a higher density and has a faster growth rate than olive flounder Paralichthys olivaceus, making it an attractive alternative for flounder farmers in Korea. As it is a relatively new species to Korean farming environments, there is no general farming protocol, which takes multiple generations to develop, for turbot in Korea. Nevertheless, we applied breeding technology to develop a stock, which we considered first-generation turbot. Then we compared its growth rate (an important economic trait) to different populations (the original stock of Korean turbot, French turbot, and Chinese turbot). The four different populations were grown in similar culture conditions. First-generation Korean turbots grew about 28% faster than all others. We will continue to select for important traits such as color, disease resistance, and heat tolerance in this turbot broodstock; we believe that with the appropriate selection process, Korean turbot should become competitive in the markets, and will become a major farming species in the Korean aquaculture industry.

A Population ecological study of the hen clam(Mactra chinensis) in the Dong-li self-regulatory community of Busan (부산 동리어촌계 개량조개, Mactra chinensis의 자원생태학적 연구)

  • Park, Hee-Won;Zhang, Chang-Ik
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.44 no.2
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    • pp.129-140
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    • 2008
  • This study was performed to estimate biomass and to provide management plan through population ecological characteristics, including growth parameters, survival rate, instantaneous coefficient of natural and fishing mortalities, and age at first capture of hen clam, Mactra chinensis, in the Dong-li self-regulatory community of Busan. The von Bertalanffy growth parameters estimated from a non-linear regression were $SH_{\infty}=86.24mm$, K=0.12/year, and = -1.37year. Survival rate(s) of the hen clam was 0.515. The instantaneous coefficients of natural mortality(M) was estimated to be 0.232/year and fishing mortality(F) 0.432/year for hen clam. The current biomass of the hen clam in the study area was estimated to be 713mt and the acceptable biological catch(ABC) was estimated under various harvest strategies based on $F_{0.1}$ and $F_{40%}$.

Survival and Growth of Sea Cucumber(Stichopus japonicus in Indoor Tank (육상수조에서 돌기해삼, Stichopus japonicus의 성장 및 생존율)

  • Kim, C.W.;Hur, J.W.
    • Journal of Practical Agriculture & Fisheries Research
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    • v.20 no.1
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    • pp.97-105
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    • 2018
  • We assessed the effects of population density on the growth and survival rate of sea cucumber(Stichopus japonicus) in indoor tank Growth of S. japonicus in high density breeding was slow overall, and body weight on 250, 350 and 500 individual/m2 group were 31.9g, 26.8g and 21.5g, respectively. The growth rate of body weight was 3.5~5.1 times according to the density of water, and the survival rate was 44.2~50.1%. The growth and survival rate were increased as decreasing the storage density. During the breeding season, small individuals tend not to be large and constantly culled, so it is necessary to set up the sorting period (etc.), and divide S. japonicus into groups of similar size.

Effect of Bacterial and Algal Symbiotic Reaction on the Removal of Organic Carbon in River Ecosystem (하천 생태계에서 유기탄소 기질 제거에 조류와 세균의 공생작용이 미치는 영향)

  • 공석기;도시유끼나까지마
    • Journal of environmental and Sanitary engineering
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    • v.16 no.3
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    • pp.22-27
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    • 2001
  • It have been investigated how algal and bacterial symbiotic reaction influences on removal of organic carbon in river ecosystem. And artificial experimentation apparatus was made for algae'and bacteia'culture as lab scale. Investigating and researching minutely the change of concentration of organic carbon substrate and the change of population density of algae'and of bacteria'with this artificial experimentation apparatus, the next results could be obtained. 1. Successful decrease of DOC(dissolved organic carbon) could not be expected unless algal and bacterial biomass floe was nut formed effectively and unless biosorption was not proceeded effectively in the very culture system in which artificial synthetic wastewater was supplied continuously at constant rate. 2. In conditions of culture liquid of 1335 glucnse mg/L(type 1) and of 267 glucose mg:L(type 2), the algal dominant species was always Chlorella vulgaris in both types in which artificial synthetic wastewater were supplied continuously at constant rate and algae population density was around maximum 107 cells/mL. 3. It was around 108 ~ 107 cells/mL that the population density of heterotrophic bacterium. In culture medium systems type 1 and type 2 in which artificial wastewater were supplied continuously at constant rate, the same density appeared initially when using the population density of Escherichia coli w 3110 as indirect indicator. And this density decreased rapidly till the culturing date 35 days were passed away, while this density increased with gentle slope after same date and then the trend of change at type 2 was more severe than one at type 1. 4. When seeing such a change of population density of Escherichia coli w 3110, the growth of heterotrophic bacterium appeared as survival instinct pattern of broader requirement of nutrient at condition of low concentration of organic carbon substrate than condition of high concentration of same substrate.

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Analysis of the Factors Affecting on Internal Population Migration in Seoul Metropolitan Area (수도권 도시유형별 내부 인구이동 영향요인 분석)

  • Kim, Sang-Won;Lee, Hoon-Rae
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.9
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    • pp.737-744
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    • 2016
  • Seoul Metropolitan Area has been changed by fierce internal migration during the last several decades. To determine the regional structure, we analyzed the in-and-out migration pattern and main factors affecting the intense of mobility. The migration within metropolitan city and province shows that in Seoul, Songpa and Dobong Gu gained a large population, in Incheon, Namdong Gu experienced a huge population influx, and in Gyeonggi Province, Hwasung, Yongin and Paju city gained a great population. In Seongnam, Suwon city lost a lot of population. These population gains and losses came from mainly residential redevelopment projects in the metropolitan city and new land development projects in Gyeonggi Province. The main factors affecting the intense of mobility diverse from city characters. In central type cities, house price gets the more population influx. In job-housing balanced cities, total income growth rate, housing supply rate and roads cause in-migration. In bed-town type cities, the increase of housing supply rate and parks increase the population. In suburban type cities, business density, housing supply rate, housing, subway station number and educational facilities increase population from outside the city. So, we have to prepare more detailed urban and housing policy responses.

ESTIMATION OF THE SURVIVAL RATE IN FISH POPULATION FROM THE LENGTH COMPOSITION AND THE GROWTH EQUATION1 (체장조성과 성장곡선식에서 생잔율을 추정하는 방법)

  • SHIN Sang Taek
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.10 no.2
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    • pp.137-143
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    • 1977
  • A study has been made to find out a new method of calculating the survival rate of a fish population from length composition and growth equation. 1. In the steady state of the fish population, let the total mortality rate be z, the age of complete recruitment $\alpha$, and the number of $\chi$ year class $N_\chi$. Then ire obtain $$N\chi=N\alpha\;\exp\;{-z(\chi-\alpha)}$$ Let the oldest age in the catch be h, the average age between the age of complete recruitment and the oldest age in the catch $U\chi$. Then we have $$U\chi=\frac{a-b\;\exp\;(-z(b-a))}{1-\exp\;(-z(b-a))}+\frac{1}{z}....(1)$$ and then let be infinite. Then we obtain $$Z=\frac{1}{U\chi-\alpha....(2)$$ 2. Calculating numerical value of $U\chi$ from age composition table and growth equation and substitute in (1) or (2) for it, we may obtain the value of s and $\varrho^{-z}$. 3. This method is applied t a case of yellow croaker in the Yellow Sea and the East China Sea. The results are as follows: Total mortality rate 0.82595 Survival rate 0.43782 95 percent confidence interval 0.43767-0.43797.

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Toxicity Assessment of Phenanthrene using the Survival and Population Growth Rate of the Marine Rotifer, Brachionus plicatilis (해산로티퍼(Brachionus plicatilis)의 생존 및 개체군 성장률을 이용한 Phenanthrene의 독성평가)

  • Hwang, Un-Ki;Choi, Hoon;Jang, Soo-Jung;Heo, Seung;Lee, Ju-Wook
    • Korean Journal of Environmental Biology
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    • v.35 no.4
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    • pp.573-580
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    • 2017
  • The oxicity assesment of Phenanthrene (PHE) has been investigated by using the rate (r) of survival and population growth in rotifer Brachionus plicatilis. The survival rate was determined after 24 h of exposure to PHE. The survival rate of PHE had no effect at a maximum of $300mg\;L^{-1}$. The r was determined after 72 h of exposure to PHE. It was observed that r in the controls (absence PHE) was greater than 0.5, but that it suddenly decreased with an increased concentration of PHE. PHE reduced r in a dose-dependent manner and a significant reduction occurred at a concentration of greater than $37.5mg\;L^{-1}$. The $EC_{50}$ value of r in PHE exposure was $63.7mg\;L^{-1}$. The no-observed-effect-concentration (NOEC) of r in PHE exposure was $18.8mg\;L^{-1}$. The lowest-observed-effect-concentration (LOEC) of r in the PHE exposure was $37.5mg\;L^{-1}$. From the results, the concentration of PHE (greater than $37.5mg\;L^{-1}$) has a toxic effect on the r of B. plicatilis in natural ecosystems. These results(including NOEC, LOEC and $EC_{50}$) might be useful for the Polycyclic aromatic hydrocarbons(PAHs) toxicity assessment in marine ecosystems.