• Ocean Science Journal
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• 제41권4호
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• pp.211-219
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• 2006

A comparison was made of population of the economically important cockle Anadara (=Scapharca) broughtoni (Bivalvia, Arcidae) inhabiting different areas of the Razdolnaya River estuary at the head of Amurskii Bay (Peter the Great Gulf, East Sea). Also, changes in cockle population density and structure, as well as in cockle growth rates during the last 20 years were studied. In all years of investigation, the morphometrical parameters and growth rates of cockles were smaller at the sites located close to the River mouth than farther down-estuary. The differences can be attributed to higher concentration of suspended particulate matter, decreased salinity and water temperature, as well as a longer exposure to these unfavorable environmental factors at sites located close to the River mouth, compared to farther sites. For two decades, cockle population density had decreased by almost 30 times at some sites in the River estuary. The main reason for this population decline is commercial over-fishing of the cockle. Besides, for the last 20 years, linear parameters of the cockles in the population decreased approximately by 30% and weight parameters, almost two times. Cockle growth rates also decreased for this period. Evidently, these facts are due to the damaging effect of dredging.

• 한국인구학
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• 제17권2호
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• pp.116-135
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• 1994

China's population and family planning program has heen successful. Women's fertility as measured by total fertility rate (TFR) has declined from 5.8 in 1970 to 2.3 in 1990, accordingly the annual crude birth rate(CBR) has declined from 34 per thousand in 1970 to 21 per thousand in 1989, and the annual natural growth rate from 2.6 percent in 1970 to 1.4 percent in 1989 (Coale and Chen, 1987; SSB, 1991; Gu, 1994). While this is indeed an astonishing achievement for a developing country to have its fertility down to replacement within a short period, some new issues emerging along with the rapid fertility decline require careful considerations. One of them is the uprising of the sex ratio at birth in China. The 1990 population census reported the sex ratio at birth in China of 113.8 in 1989, which is ohviously much higher than the acceptable level of normal ratio around 106. It has received since then a lot of tention in China and abroad, among demographic professionals and governmental agencies alike (Hull, 1990; Johansson and Nygren, 1991; Xuand Guo, 1991; Tu, 1993; Gu and Xu, 1994; among others). Based on the available demographic data and research results this paper will first have a review of the patterns and trends of sex ratio at birth in China, then turn to the immediate causes of abnormal sex ratio at birth and the determinants of the son preference, followed with a conceptual framework for understanding of the phenomenon, and finally the policy implications and recommendations will be discussed.

• 농촌계획
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• 제30권2호
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• pp.79-96
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• 2024

The purpose of this study is to analyze the factors affecting residential mobility between urban and rural. After classifying urban and rural region based on discriminatory attributes of the regions, we applied a multinomial logistic model, using the sample data of 2020 Korea Population and Housing Census. The major findings are as follows. The young highly educated in cities avoided rural. The young less educated in rural engaged in 2, 3th industries as well as agricultural industry, but remained in low-paying and unstable jobs. In addition, various classes moved to rural and rising house prices in cities pushed people to rural. Therefore, it is necessary to develop diversified regional industry models and provide opportunities for high quality and stable jobs in rural by linking industrial demand, education and jobs. Also, preserving the rural environment, settlement conditions and residential environment are needed for satisfying various needs of urban residents who migrate to rural areas. While regional policies so far have focused on maintaining the population size and promoting a population influx, rural development and population policies should be established in a way that responds to diverse population classes in an era of population decline.

• 농촌계획
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• 제29권3호
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• pp.15-24
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• 2023

The sense of crisis regarding regional extinction due to low birth rates and an aging population is expanding. Generally, the local extinction index is used to analyze local extinction. However, it is challenging to diagnose the actual situation of village extinction risk in rural areas, even though the regional extinction index can be analyzed in units such as Si-Gun-Gu and Eup-Myeon-Dong. This difficulty arises because the regional extinction index solely relies on natural population growth indicators (elderly population and female population aged 20-39). Therefore, the purpose of this study is to develop a village extinction index that can identify the disappearance of rural villages. Additionally, the aim is to apply the developed indicators to the village (administrative ri) spatial unit. The existing regional extinction index used only mortality-related indicators as factors for natural population decline and fertility-related indicators as factors for natural population growth. However, the developed village extinction index included not only the factors of natural population change but also incorporated social population growth factors and factors related to the pace of village extinction. This is the key difference between the developed village extinction index and the existing regional extinction index. In this study, the indicators of "total population," "number of young women aged 20-44," "number of elderly population aged 70 or older," and "number of incoming population" were selected to develop a village extinction index. The village extinction index was developed by incorporating both natural population growth indicators and social population growth indicators. The developed village extinction index was applied to administrative villages. This research is expected to provide a more accurate understanding of the current state of rural villages facing extinction.

• Integrative Medicine Research
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• 제5권3호
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• pp.176-181
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• 2016

Recent studies have focused on evidence-based interventions to prevent mobility decline and enhance physical performance in older adults. Several modalities, in addition to traditional strengthening programs, have been designed to manage age-related functional decline more effectively. In this study, we reviewed the current relevant literatures to assess the therapeutic potential of eccentric exercises for age-related muscle atrophy (sarcopenia). Age-related changes in human skeletal muscle, and their relationship with physical performance, are discussed with reference to in vitro physiologic and human biomechanics studies. An overview of issues relevant to sarcopenia is provided in the context of the recent consensus on the diagnosis and management of the condition. A decline in mobility among the aging population is closely linked with changes in the muscle force-velocity relationship. Interventions based specifically on increasing velocity and eccentric strength can improve function more effectively compared with traditional strengthening programs. Eccentric strengthening programs are introduced as a specific method for improving both muscle force and velocity. To be more effective, exercise interventions for older adults should focus on enhancing the muscle force-velocity relationship. Exercises that can be performed easily, and that utilize eccentric strength (which is relatively spared during the aging process), are needed to improve both muscle force and velocity.

• 한국식품과학회지
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• 제54권1호
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• pp.52-58
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• 2022

Phosphatidylserine (PS) is an essential component of the cerebral cortex and is associated with cognitive function. In this systematic review, the effects of PS on cognitive function in the elderly population are examined. The literature search included PubMed, EMBASE, Cochrane, and Web of Science databases. Subsequently, nine studies, including five randomized controlled trials and four pre-post studies, were selected. There were 961 participants in the selected studies; PS dosage varied from 100 to 300 mg/d, and the experimental period ranged from 6 weeks to 6 months. Five out of the nine selected studies were assessed to have a 'low' risk of bias, whereas the other four studies were assessed to have 'some concerns' regarding the risk of bias. The results of the meta-analysis concluded that PS had a positive effect on the memory of older adults with cognitive decline. Thus, PS appears to improve age-associated cognitive decline, especially memory, with no adverse effects.

• KDI Journal of Economic Policy
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• 제39권2호
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• pp.25-51
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• 2017

This paper employs an Overlapping Generations Model to quantify the impacts of Korea's demographic transition toward an older population on the total output growth rate. The model incorporates the projected population through 2060 according by Statistics Korea. The effects of the low fertility and increased life expectancy rates are studied. The model is considered suitable for analyzing the effects of demographic changes on the Korean economy. Under the assumption that the TFP growth rate will not slow considerably in the future, remaining at 1.3% per annum, the gross output growth rate of the Korean economy is projected to slow to 1.1% per annum in the 2050s, from 4.0% in the 2000s. The shrinking workforce due to the decline in fertility plays a significant role in the deceleration of the Korean economy. The increased life expectancy rate is expected to mitigate the negative effect, but the magnitude of its effect is found to be limited.

• International Journal of Industrial Entomology and Biomaterials
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• 제24권1호
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• pp.41-47
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• 2012

The Scarites aterrimus (Coleoptera: Carabidae) dwells exclusively on coastal sandy dunes. Previously, we investigated the nation-wide magnitude and nature of genetic diversity of the species using mitochondrial COI gene and found moderate to low magnitude of sequence diversity, the presence of closely related haplotypes, and relatively high gene flow estimate. Based on these observations we concluded that the species had no historical barriers that bolster genetic subdivision and possible population decline. In this study, we additionally sequenced mitochondrial COII gene from 23 individuals collected from 9 Korean localities to confirm previous findings. Sequencing of 688 bp COII gene provided 5 haplotypes ranging in sequence divergence from 0.145% to 0.291% (1 ~ 2 bp), further confirming low sequence divergence of the species. Gene flow estimates and genetic diversity estimates also support the previous findings that there had been no historical barriers that bolster genetic subdivision.

• 융합정보논문지
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• 제9권11호
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• pp.1-7
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• 2019

제주시는 원도심의 거주인구와 유동인구 모두가 줄어드는 원도심쇠퇴 현상이 나타나는 도시 중 하나이다. 제주시 원도심 쇠퇴는 1990년대 이후 본격화되고 있으며, 2000년대 들어 점점 심화되고 있는 실정이다. 이에 따라 제주시는 원도심의 역사문화자원을 활용한 도심관광 활성화 방법과 산업경제 영역 정비를 하여 원도심 상권 활성화 방안을 추진하고 있다. 본 논문에서는 제주시 원도심 공영관광지인 제주목관아에 증강현실기술을 이용하여 원도심 상권 활성화에 도움이 되는 방문객을 증가시키는 방법을 제안한다. 제주목관아를 소재로 한 증강현실 콘텐츠를 스마트폰기반으로 구현하고 시범운영을 하면서 효과를 분석하기 위한 설문조사를 수행한다. 설문조사는 온라인/오프라인을 통한 홍보를 통하여 제주목관아를 찾은 관람객 574명을 대상으로 자기기입 방식으로 수행한다. 설문조사 결과를 바탕으로 제안한 방법이 유동인구를 증가시킴으로써 원도심 상권 활성화에 효과적으로 사용될 수 있음을 보인다.

• Asian-Australasian Journal of Animal Sciences
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• 제31권8호
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• pp.1078-1087
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• 2018

Objective: The genetic diversity of the Landrace population, a representative maternal pig breed in Korea, is important for genetic improvement. Previously, the effective population size (Ne) has been used to infer the genetic diversity of a population of interest. In this study, we aimed to use single nucleotide polymorphism (SNP) data to characterize linkage disequilibrium (LD) and the Ne of the Korean Landrace population. Methods: We genotyped 1,128 Landrace individuals from three representative Korean major grand-grand-parent (GGP) farms using the Illumina PorcineSNP60 version2 BeadChip, which covers >61,565 SNPs located across all autosomes and mitochondrial and sex chromosomes. We estimated the expected LD and current Ne, as well as ancestral Ne. Results: In the Korean Landrace population, the mean LD ($r^2$) of 3.698 million SNP pairs was $0.135{\pm}0.204$. The mean $r^2$ decreased slowly with as the distance between SNPs increased, and remained constant beyond 3 Mb. According to the $r^2$ calculations, 8,085 of 3.698 million SNP pairs were in complete LD. The current Ne (${\pm}$standard deviation) of the Korean Landrace population is approximately 92.27 [79.46; 105.07] individuals. The ancestral Ne exhibited a slow and steady decline from 186.61 to 92.27 over the past 100 generations. Additionally, we observed more a rapid Ne decrease from the past 20 to 10 generations ago, compared with other intervals. Conclusion: We have presented an overview of LD and the current and ancestral Ne values in the Korean Landrace population. The mean LD and current Ne for the Korean Landrace population confirm the genetic diversity and reflect the history of this pig population in Korea.