• Journal of Ecology and Environment
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• v.48 no.2
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• pp.144-151
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• 2024

Background: This study focused on the diet of Clithon retropictum, level II endangered species in Korea. Since the development of brackish water zones has led to a decline in the population of this species, to obtain information on the ecology of C. retropictum required for its conservation and restoration. To investigate the actual preys of C. retropictum in south coast of Korea, we conducted high-throughput sequencing and metabarcoding techniques to extract DNA from gut contents and periphyton in their habitats. Results: Total 118 taxonomic groups were detected from periphyton samples. 116 were Chromista and Cyanobacteria dominated in the most samples. In gut contents samples, 98 taxonomic groups were detected. Similar to the results of periphyton, 96 were Chromista and Cyanobacteria dominated in the most samples. In the principal component analysis based on the presence/absence of taxonomic groups, gut content composition showed more clustered patterns corresponding to their habitats. Bryophyta was the most crucial taxonomic group explaining the difference between periphyton and gut contents compositions of C. retropictum. Conclusions: Our finding suggests that C. retropictum may not randomly consume epilithic algae but instead, likely to supplement their diet with Bryophyta.

• Design & Manufacturing
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• v.18 no.2
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• pp.35-40
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• 2024

Injection molding is a process widely used across various industries for molding plastics, and it is the most commonly applied process in root industries utilizing molds. Among the different types of injection molding, insert injection molding, where busbars are used as inserts, is increasingly being applied in the electric vehicle industry. However, currently, the insert injection molding process is manually performed, with workers placing insert components by hand before injection molding. This results in issues related to productivity, safety, and quality. Additionally, there is a growing demand for automation of such production lines due to hazardous working conditions, economic difficulties in the manufacturing industry, and the decline in the labor force caused by an aging population. This study focuses on the application of an automated system for the insert injection molding process used in electric vehicles. The development of an automated system for the transport and insertion of insert components, as well as the inspection and stacking processes after injection, has resulted in over a 25% improvement in productivity and more than a 27% reduction in defect rates.

• The Korean Journal of Ecology
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• v.28 no.5
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• pp.305-320
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• 2005

Recently 64 species in Korea have been ranked as rare and endangered taxa by the Ministry of Environment using two categories, I and II. The original threat categories produced by the Ministry of Environment were developed to provide a standard for specifying animals and plants in danger of extinction and has been influential sources of information used in species conservation in Korea. However, the criteria by Ministry of Environment were applied to the whole taxa only by regional boundaries, especially in South Korea, rather than international context, and it also lacked an explicit framework that was necessary to ensure repeatability among taxa because of the absence of quantitative criteria to measure the likelihood of extinction. The World Conservation Union (IUCN) has developed quantitative criteria for assessing the conservation status of species. The threatened species categories, the 2000 IUCN Red List, proposed by SSC (Species Survival Commission) of IUCN have become widely recognized internationally. Details of threatened Korean plants, identified by applying the IUCN threat categories and definitions, were listed and analyzed. The number of species identified as threatened was only 34 out of 64 taxa (48.4%), while the rest of taxa were rejected from the original lists. Many of the species (51.6%, 33 taxa) excluded from the original list proposed by Ministry of Environment do not qualify as Critically Endangered, Endangered or Vulnerable because these taxa were widely distributed either in Japan or in China/far eastern Russia and there is no evidence of substantial decline in these countries. An evaluation of taxa in Korea has been carried out only based on subjective views and qualitative data, rather than quantitative scientific data, such as rates of decline, distribution range size, population size, and risk of extinction. Therefore, the national lists undermine the credibility of threatened species lists and invite misuse, which have been raised by other cases, qualitative estimate of risk, political influence, uneven taxonomic or geographical coverage. The increasing emphasis on international responsibilities means that global scale is becoming more significant. The current listings by Environment of Ministry of Korea should be challenged, and the government should seek to facilitate the resolution of disagreements. Especially the list should be flexible enough to handle uncertainty and also incorporates detailed, quantitative data. It is suggested that the highest priorities for the Red List should be given to endemic species in Korea first. After setting up the list of endemic species to Korea, quantitative data on population size and structure, distributional range, rated of decline, and habitat fragmentation should be collected as one of long term projects for the Red list categories. Transparency and accountability are the most important key factors. Also, species assessors are named and data sources referenced are required for the future objective evaluations on Korean plant taxa.

• KDI Journal of Economic Policy
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• v.31 no.2
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• pp.127-153
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• 2009

There is a growing concern about potential harmful effect of second-hand or environmental tobacco smoking. As a result, smoking bans in workplace become more prevalent worldwide. In Korea, workplace smoking ban policy become more restrictive in 2003 when National health enhancing law was amended. The new law requires all office buildings larger than 3,000 square meters (multi-purpose buildings larger than 2,000 square meters) should be smoke free. Therefore, a lot of indoor office became non smoking area. Previous studies in other counties often found contradicting answers for the effects of workplace smoking ban on smoking behavior. In addition, there was no study in Korea yet that examines the causal impacts of smoking ban on smoking behavior. The situation in Korea might be different from other countries. Using 2001 and 2005 Korea National Health and Nutrition surveys which are representative for population in Korea we try to examine the impacts of law change on current smoker and cigarettes smoked per day. The amended law impacted the whole country at the same time and there was a declining trend in smoking rate even before the legislation update. So, the challenge here is to tease out the true impact only. We compare indoor working occupations which are constrained by the law change with outdoor working occupations which are less impacted. Since the data has been collected before (2001) and after (2005) the law change for treated (indoor working occupations) and control (outdoor working occupations) groups we will use difference in difference method. We restrict our sample to working age (between 20 and 65) since these are the relevant population by the workplace smoking ban policy. We also restrict the sample to indoor occupations (executive or administrative and administrative support) and outdoor occupations (sales and low skilled worker) after dropping unemployed and someone working for military since it is not clear whether these occupations are treated group or control group. This classification was supported when we examined the answers for workplace smoking ban policy existing only in 2005 survey. Sixty eight percent of indoor occupations reported having an office smoking ban policy compared to forty percent of outdoor occupation answering workplace smoking ban policy. The estimated impacts on current smoker are 4.1 percentage point decline and cigarettes per day show statistically significant decline of 2.5 cigarettes per day. Taking into account consumption of average sixteen cigarettes per day among smokers it is sixteen percent decline in smoking rate which is substantial. We tested robustness using the same sample across two surveys and also using tobit model. Our results are robust against both concerns. It is possible that our measure of treated and control group have measurement error which will lead to attenuation bias. However, we are finding statistically significant impacts which might be a lower bound of the true estimates. The magnitude of our finding is not much different from previous finding of significant impacts. For cigarettes per day previous estimates varied from 1.37 to 3.9 and for current smoker it showed between 1%p and 7.8%p.

• Korean Journal of Social Welfare
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• v.57 no.3
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• pp.337-361
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• 2005

This study seeks the implications for the Korean family welfare policies after examining the characteristics of fertility rates and family welfare policies of advanced OECD countries, and comparatively analyzing the fertility rates among clusters of countries having similar family welfare policies. The fertility rates of most advanced OECD countries declined below the population replacement level in the 1970s, and continuously declined slowly after that period. But in the 1990s the fertility rate of some countries increased, on the other hand that of other countries declined. Such a difference of fertility rates suggests that there is some correlation between the fertility rate and the family welfare policy of each country. Advanced countries became concerned about the decline of fertility rate, established the government Population Issues Committee in order to deal with population problems, and increased family welfare supports. But the level and pattern(focusing on maternal employment supports or child-rearing supports) of each country's family welfare policies are differently developed according to its political ideology, cultural and historical background, and economic environments. A comparative assessment of the fertility rate among clusters of countries having similar family welfare policies demonstrates that the higher the level of family welfare supports is and the level of maternal employment supports in comparison with that of maternal child-rearing supports is, the higher of fertility rate is. And a comparative assessment of the fertility rate changes among clusters of countries also shows that the higher the level of family welfare supports is and the level of maternal employment supports in comparison with that of maternal child-rearing supports is, the higher the increase of fertility rate is or the lower the decrease of fertility rate is. The implications for the Korean family welfare policies are summarized as follows. First, it is necessary to establish the government Population Issues Committee which can study systematically fertility rates and population problems, and provide comprehensive population measures. Second, family welfare supports should be expanded through the establishment of family allowances, the prolongation of maternity leave and child-care leave and the upward readjustment of child-care leave benefits, and the extension of public child-care facilities. Third, maternal employment supports such as public child-care facilities and maternity leave should be given more weight than maternal child-rearing supports such as family allowance. Fourth, it is required to prepare social environments which can provide the youth with the hope that child-rearing is not difficult and gives them happiness.

• Therapeutic Science for Rehabilitation
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• v.7 no.2
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• pp.29-40
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• 2018

Objective : The purpose of this study was establishing clinical norms of TEMPA Korean version for Korean adult population in addition to identifying characteristics of hand function by age and gender based on the collected data. Methods : A total of 138 healthy adults between ages 20 and 59 were recruited by continuous sampling. All subjects had been employed TEMPA Korean version and Jarmar dynamometer and pinch gauge to evaluate hand function and strength. Results : The results showed that there were no statistically significant difference in overall hand function among the age groups and between genders. Also, while there were no significant differences in overall speed and qualitative movement, age groups of 40s and 50s showed a declining tendency in speed in some of the tasks. Also, hand strength increases up to 40s and start declining from the 50s, but most results did not show significant differences among the age groups. Conclusion : Normative data of TEMPA Korean version for Korean adult population was established, therefore, it can be used in clinical setting and research as evidence based. Furthermore, occupational therapists need to consider about the signs of decline in hand function and strength in middle-aged adults and to provide education programs to maintain their hand function.

• Journal of the Korean association of regional geographers
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• v.3 no.1
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• pp.35-50
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• 1997

The purpose of this research seeks to analyze the spatial variations in the sex age structure which have been shown to exist within the study atrea, the Kyonggi province in Korea. In this study it is desired to use the Age Structure Index developed by Coulson in order to describe thi sex age structure of each of 186 tracts that comprise the tracted portion of the Kyonggi province. The mechanics of computing the Age Structure Index are found in the equation describing a linear least squares trend line: y=a+bx. For each census tract, the percentage of the population in each age group(y) was plotted against the middle age of each age group(x). The a is a constant representing the value of y, when x equals zero. The b is the regression coefficient and is a measure of the angle of the slope of the least squares trend line. Thus the value of b is the Age Structure Index for each census tract. The major results of this investigation can be summarized as follows: The spatial distributions of sex age structures in the Kyonggi province are far from random. They have exhibited great regularity with the yonger sex age structures near Seoul and a sharp decline to the older sex age structures out in all derections towards rural region. The results of this investigation should have important general significance for the study of the Kyonggi province Age Structure Index is a flexible, operational definition shich allows sex age structure to be measured, mapped, and incorporated in a wide variety of methods of statistical analysis. Futurer, it has been demonstrated that sex age structure varies spatially within Seoul metropolitan finge and that this variation is relagfed to many other attributes of the population. Especially, Age Structure Index is strongly related to the variables-rate of population growth rate. density, rate of numbers of manufacturing, land price. At the same time, considerably more research is needed before a genmeral body of knowlege concerning sex age structure can be developed.

• Korean Journal of Microbiology
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• v.34 no.4
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• pp.188-193
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• 1998

The authors examined the variations of environmental factors, the distributions of cyanobacteria, heterotrophic bacteria, and microorganisms that inhibit the growth of Anabaena cylindrica according to development and extinction of cyanobacterial bloom at a site in Daechung Dam reservoir. And certified the relationship between each other. Water temperature variated in a typical pattern. pH and concentrations of dissolved oxygen and chlorophylla was high in bloom period, and lowered with the decline of bloom. Phosphorus played as a growth-limiting factor at this study site. Total nitrogen concentration increased during blooming period, which indicated that nitrogen has been fixed by aquatic organisms such as cyanobacteria. Cyanobacteria distributed from June 17, and such cyanobacterial species as Anabaena spp., Aphanizomenon spp., Microcystis spp., Oscillatoria spp. and Phormidium spp. was detected during study period. Anabaena spp. distributed relatively highly distributed from July 23 to September 22, and disappeared completely at September 29. Heterotrophic bacterial and cyanobacterial populations varied inverse-proportionally. There was a relevancy between the variations of Anabaena spp., heterotrophic bacteria, and microorganisms that inhibit the growth of Anabaena cylindrica. Microorganisms that inhibit the growth of Anabaena cylindrica distributed from early growth phase of Anabaena spp. population to immediately after the extinction of Anabaena spp. With the population of Anabaena cylindrica growth-inhibiting microorganisms decreasing, increases of heterotrophic bacterial population followed it. Thease results indicate that microorganisms have a part in the extinction of cyanobacterial bloom, especially at its destroying period.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.3
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• pp.290-298
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• 2019

The proportion of farm households in the total population is decreasing every year. The aging of rural areas is expected to deepen. The aging of agriculture is continuing due to the aging of the aged population and the decline of the young population, and agricultural manpower shortage is emerging as a threat to agriculture and rural areas. The existing facility cultivation was concentrated on the production / yield per unit area. However, nowadays, not only production but also crop quality should be good so that the quality of crops must be improved because they can secure competitiveness in the market. Therefore, the government plans to increase the productivity by hi-techization of ICT infrastructure horticulture and to plan the dissemination of energy saving smart greenhouse. Therefore, it is necessary to develop a Smart Farm convergence service system based on a hybrid algorithm to enhance diversity and connectivity. Therefore, this study aims to develop smart farm convergence service system which collects data of growth environment of the rhizosphere environment of crops by wireless and monitor smartphone.

• Korean Journal of Ornithology
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• v.25 no.2
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• pp.87-93
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• 2018

In order to investigate the changes in the population of Spot-billed ducks due to changes in reclaimed land, we conducted a monthly survey from January 2008 to December 2014 at the Shihwa Lake. The average number of Spot-billed ducks was 12,204 individuals. The average population was decreased. The yearly index of fluctuation (Fi) was the highest at 2.16 in 2010. TRIM(TRends and Indices for Monitoring data) showed a steep decline in winter and a moderate decrease tendency in autumn and spring. However, in the summer season, it showed an moderate increasing tendency. The main habitat were Northland reclaimed land, agricultural land and wetland area, Tando waterway, Shihwa artificial wetland in upstream. The correlation between the number of Spot-billed ducks and the temperature was negatively correlated in spring, summer, autumn. However, winter was showed positive correlation. Therefore, it affects the community of Spot-billed ducks due to environmental changes of reclaimed land. In future, effective management is needed to prepare alternative habitat based on basic data like this study for the conservation and management of Spot-billed ducks during reclamation construction.