• Korean Journal of Environment and Ecology
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• v.37 no.1
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• pp.70-75
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• 2023

This study was conducted from October 2021 to October 2022 at Gulup island, Incheon, South Korea, to identify activity patterns of Formosan sika deer (Cervus nippon taiouanus) introduced in island areas, using camera trapping. We described the daily activity patterns of Formosan sika deer in each season by analyzing kernel density estimates of capture frequency and checked seasonal differences in daily activity patterns by analyzing the overlap coefficient between seasons. Formosan sika deers introduced to Gulup island showed a crepuscular behavior pattern only in winter and no distinct pattern from spring to fall. The crepuscular behavior pattern is typical for deers to reduce the risk of predation, and it is determined that Formosan sika deers introduced to Gulup island were affected by population control of the species by the local government in the winter. It was in contrast to the fact that human activities, such as backpacking, frequently carried out from spring to fall, did not affect the behavior of Formosan sika deers. Moreover, low winter temperatures have been shown to affect the nocturnal activities of Formosan sika deers in winter. The behavior patterns of Formosan sika deers overlapped least between summer and winter due to cold winter weather and population control. The relationship between the temporal status of Formosan sika deers and seasonal temperature confirmed in this study can be important basic ecological data for establishing control measures of Formosan sika deers introduced not only in islands but also in inland.

• Korean Journal of Ecology and Environment
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• v.42 no.3
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• pp.317-330
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• 2009

To diminish the levels of organic matters, a novel S-CROM (continuous removal of organic matters in the stream system using freshwater bivalve), was developed and applied to the polluted stream discharging from the wastewater treatment plant, Pocheon stream, Pocheon city (Korea). Major pollutants of the stream were human population and industrial wastewaters. The study was conducted at a small dam constructed within the stream, often called 'bo', and designed with four tanks; no mussels and no sediment (negative control), no mussels and sediment (positive control), 30 mussels and sediment (D1), and 60 mussels and sediment (D2). Physicochemical and biological parameters were measured at 12 hours interval (day and night) after mussel stocking. Results indicated that Anodonta woodiana Lea (D2) clearly removed approximately 72% of chl-$\alpha$ and 57% of suspended solids on second day, however, there were no differences in removal activities between animal densities (P>0.5). Dislike a laboratory CROM system, which previously developed, there were no huge release of nutrient ($NH_3$-N and SRP), due perhaps to the higher flow rate and the lower animal density. Therefore, we may suggest that if we can determine the relevant current and the animal density considering the stream state, an S-CROM system has a strong potential to water quality improvement of eutrophic streams. Some characteristics on both CROM and S-CROM were compared.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.5
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• pp.365-372
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• 2001

The objective of this study was to determine the effects of various kinds of composts on the change of soil physical properties and microorganism in upland soils. Field experiments were conducted in the loam and sandy loam soils, while the clay loam and sandy loam soils were used for laboratory experiments. Various kinds of composts such as poultry manure compost(PMC). cow manure compost(CMC). human excrement sludge(HES), and food industrial sludge compost(FISE) were applied annually at rates of 0, 40, and $80Mg\;ha^{-1}$ to soils grown with soybean and maize plants for 4 years during 1994 to 1997. The results of this study were as follows : Bulk density of loam soil decreased with compost application to $1.07{\sim}1.32Mg\;m^{-3}$ compared with $1.49Mg\;m^{-3}$ of control plot, while in sandy loam soil it decreased to $1.00{\sim}1.20Mg\;m^{-3}$ compared with $1.25Mg\;m^{-3}$ of control plot. Bulk density of soil was decreased according to maize cultivation compared with bare control, but soybean cultivation was similar. Population of organic material decomposing microorganisms was increased rapidly at the initial incubation stage at $25^{\circ}C$, and increased more sensitively at the loam soil than sandy loam soil. In the case of the change of microorganisms associated with nitrogen circulation, ammonia oxidizing bacteria was more at the initial incubation stage, and denitrifying bacteria was more at the initial incubation stage, and denitrifying bacteria increased until 1~4 weeks after incubation and increased more at the loam soil than sandy loam soil.

• Parasites, Hosts and Diseases
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• v.24 no.1
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• pp.15-24
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• 1986

The species composition, population density, and seasonal prevalence of vector mosquitoes in an inland area of Kyungoook Province were studied, based on light trap and human bait trap collections, and the recent patterns of infestation for infective larvae of Brugia malayi in these vector hosts were investigated from May to November in 1985. Nine species in four genera of mosquitoes were collected by light trap, human bait trap, and/or by nets. Anopheles sinensis Wiedemann was the most abundant species collected by light traps during this year. Culex tritaeniorhynchus Giles was the second abundant species, and Aedes vexans nipponii (Theobald) ranked third in total abundance. The earlist time when A. sinensis were found was the middle of May. At that time the temperature ranged from $14.3^{circ}{\;}to{\;}22.8^{\circ}C$ and the humidity 53~90 per cent. The month of highest average nightly catch was July, when the temperature was between $21.5^{circ}{\;}and{\;}30.6^{\circ}C$ and the humidity 72~91 per cent. The peak time of biting activity of mosquitoes was different in each month, i.e. between 22:00~23:00 in July, and 20:00"-'21:00 hours in September, when the temperature was between $24.3^{circ}{\;}and{\;}26.5^{\circ}C$ and the humidity 73~88 per cent in the field. While infective larvae of B. malayi were reported to have been found in one species of mosquito in 1975, no larvae were found in any species collected in this survey.

• Korean Journal of Human Ecology
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• v.13 no.6
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• pp.1037-1046
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• 2004

Age-dependent changes in body fat can often be observed in normal population. A series of indirect body fat estimates, such as hydrodensitometry, Bioelectrical Impedance Analysis(BIA), and anthropometry equation for body fat, have been developed. The BIA made it possible to analyze body fat mass more related to hydrodensitometry than anthropometry. This study is to compare the body composition analysis between bioelectrical impedance analysis(BIA) and anthropometric measurements of women. The subjects were a group of Daejeon residents including 32 young-aged women($21.50{\pm}1.44$), 30 middle-aged women($50.33{\pm}5.27$), and 40 old-aged women($69.22{\pm}5.74$). We used BIA(inbody 3.0, Biospace Korea) to determine body fat and other body composition. We also measured weight, height, circumference for 12 parts, and skinfold thickness for 9 parts of all subjects' body. The results are as follows: The subjects' height by the age group were $161.74{\pm}0.94cm$ in the young-aged women, $154.16{\pm}1.09cm$ in the middle-aged, and $148.60{\pm}0.78cm$ in the old-aged respectively. BMI were, in order, $21.68{\pm}0.49,\;22.87{\pm}0.89,\;and\;23.85{\pm}0.55$. Relative body fat determined by BIA was, also in order, $29.06{\pm}0.92%,\;26.35{\pm}1.02%,and\;29.35{\pm}1.07%$. Circumference and skinfold that showed the highest correlation with body fat by BIA was waist in the young-aged(r=0.738) and bast in the middle- and old-aged(r=0.844, r=0.804), and triceps in the young-and old-aged(r=0.538, r=0.798), and subcostal in the middle-aged(r=0.872). Body fat Estimations by BIA were the highest correlation with Caucasian women's equation(r=0.588) in young-aged women, Siri's equation with Durnin & Womesley's body density measurement(r=0.875) in middle aged women and Caucasian women' equation(r=0.872) in old aged women. We need to develop specific anthropometric equations based on sex and age to determine body fat.

• Journal of the Korean Geographical Society
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• v.40 no.6 s.111
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• pp.730-747
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• 2005

This study examines relationships between climatic factors and spatial-temporal patterns and recent changes of tropical night phenomenon(TN) occurring through nighttime stages in South Korea. Frequencies of daily TN at different times of night are extracted from long term(1973-2004) 6 hourly nighttime(9PM and 3AM) temperature and daily minimum temperature data at 61 weather stations. Temporally, the occurrences of TN are more pronounced in the evening(9PM) and during the Changma Break period(late July - early August). Spatially, the TNs in the evening frequently occur in the urbanized inland cities at low latitudes due to urban heat islands, whereas the TNs in the middle of night(3AM) or at dawn frequently appeared along the coastal areas within 30km from ocean due to the thermal inertia of ocean. By contrast, the evening(dawn) TN is not seen in the highlands whose elevation is greater than 800m(300m) along the Taebaek and Sobaek mountain ridges due to temperature lapse rates with height Correlation and multivariate regression analyses reveal that the impacts of human or physical climatic factors, such as latitude, elevation, proximity to ocean, and population density, are diverse on the frequencies of TN according to nighttime stages. Recent temporal changes of the late Changma period and intensified urbanization during the 1990s have increased the occurances of TN in urban areas. Therefore, strategies to mitigate the increasing urban TN should be prepared in the near future.

• Journal of Korea Water Resources Association
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• v.51 no.7
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• pp.565-574
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• 2018

High population density in deltaic settings, especially in Asia, tends to increase and causes coastal flood risk because of lower elevations and significant subsidence. Large flood annually causes numerous deaths and huge economic losses. In this paper, an innovative technology of spatial satellite imagery has been used as tool to analyze the socio-economic flood-related damage in Mekong river basin. The relationship between nightlight intensity and flood damages has been determined for the period of 1992-2013 with a spatial resolution of 30 arc sec ($0.0083^{\circ}$), which is nearly one kilometer at the equator. Flow path distance was calculated to identify the distance of each cell to river network and to examine how nightlight intensity correlate to the area close to and far from river network. Statistical analysis results highlight the significant correlation between nocturnal luminosity intensity and flood-related damages in countries along the Mekong river (i.e., Cambodia, China, Lao PDR, Thailand, and Vietnam). This result reveals that the areas close to the river network correspond to high human distribution and causes huge damage during flooding. The result may provide key information to the region with respect to decisions, attentions, and mitigation strategies.

• Journal of Korean Society of Forest Science
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• v.110 no.3
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• pp.419-430
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• 2021

This study investigated spatiotemporal trends of sediment-related disasters in North Korea from 1960 to 2019 and post-disaster recovery cases based on a literature review and satellite images. Results showed that occurrence status of sediment-related disasters was initially externally reported in 1995 (during the Kim Jongil era); their main triggering factor was heavy summer rainfall. Furthermore, forest degradation rate was positively correlated with population density (R² = 0.4347, p = 0.02) and occurrence number of sediment-related disasters was relatively high on the west coast region, where both variables showed high values. This indicates that human activity was a major cause of forest degradation and thus, significantly affected sediment-related disasters in mountain regions. Finally, sediment- related disasters due to shallow landslides, debris flow, and slow-moving landslides were observed in undisturbed forest regions and human-impacted forest regions, including terraced fields, opencast mines, forest roads, and post-wildfire areas, via satellite image analysis. These disaster-hit areas remained mostly abandoned without any recovery works, whereas hillside erosion control work (e.g., treeplanting with terracing) or torrent erosion control work (e.g., check dam, debris flow guide bank) were implemented in certain areas. These findings can provide reference information to expand inter-Korean exchange and cooperation in forest rehabilitation and erosion control works of North Korea.

• Korean Journal of Environmental Biology
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• v.36 no.3
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• pp.412-423
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• 2018

In this study, we investigated the distribution and habitat of Tscherskia triton from 2014 to 2016 in Jeju Island. Nine individuals of T. triton were observed and captured from four habitat sites. Most of the habitats were of the natural and rural type, and urban type coexisted in some of the areas. The natural type of habitat comprised of forests, shrubs, and grasslands. The habitat of T. triton ranged vertically from 102 m in lowland to 742 m in a mountainous area and was not observed in altitude over 1,000 m. Small brooks, dry streams or wetlands were found to be located nearby the habitat of T. triton. The T. triton was distributed mainly in areas with natural vegetation and artificial plantation in company with the upper story vegetation on the ground of intact or incomplete layer structure, or the area with the relatively large distribution of shrubs and long grassland. The presence of roads and forest paths in these habitats suggested that the T. triton can thrive in areas with human disturbance. The designation of Halla Mountain National Park in Jeju Island as a conservation area prevents damage or loss of the habitat due to any artificial development. However, frequent human disturbances occurring in grassland is tolerated by small mammals. Therefore, in order to help T. triton maintain a stable population density, it is essential that various types of the habitat should be conserved in the middle mountain areas and the grasslands in lowlands should be well protected.

• KDI Journal of Economic Policy
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• v.12 no.3
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• pp.27-45
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• 1990

Two opposing views prevail regarding the economic impact of rural out-migration on the rural areas of origin. The optimistic neoclassical view argues that rapid rural out-migration is not detrimental to the income and welfare of the rural areas of origin, whereas Lipton (1980) argues the opposite. We developed our own alternative model for rural to urban migration, appropriate for rapidly developing economies such as Korea's. This model, which adopts international trade theories of nontraded goods and Dutch Disease to rural to urban migration issues, argues that rural to urban migration is caused mainly by two factors: first, the unprofitability of farming, and second, the decrease in demand for rural nontraded goods and the increase in demand for urban nontraded goods. The unprofitability of farming is caused by the increase in rural wages, which is induced by increasing urban wages in booming urban manufacturing sectors, and by the fact that the cost increases in farming cannot be shifted to consumers, because farm prices are fixed worldwide and because the income demand elasticity for farm products is very low. The demand for nontraded goods decreases in rural and increases in urban areas because population density and income in urban areas increase sharply, while those in rural areas decrease sharply, due to rapid rural to urban migration. Given that the market structure for nontraded goods-namely, service sectors including educational and health facilities-is mostly in monopolistically competitive, and that the demand for nontraded goods comes only from local sources, the urban service sector enjoys economies of scale, and can thus offer services at cheaper prices and in greater variety, whereas the rural service sector cannot enjoy the advantages offered by scale economies. Our view concerning the economic impact of rural to urban migration on rural areas of origin agrees with Lipton's pessimistic view that rural out-migration is detrimental to the income and welfare of rural areas. However, our reasons for the reduction of rural income are different from those in Lipton's model. Lipton argued that rural income and welfare deteriorate mainly because of a shortage of human capital, younger workers and talent resulting from selective rural out-migration. Instead, we believe that rural income declines, first, because a rapid rural-urban migration creates a further shortage of farm labor supplies and increases rural wages, and thus reduces further the profitability of farming and, second, because a rapid rural-urban migration causes a further decline of the rural service sectors. Empirical tests of our major hypotheses using Korean census data from 1966, 1970, 1975, 1980 and 1985 support our own model much more than the neoclassical or Lipton's models. A kun (county) with a large out-migration had a smaller proportion of younger working aged people in the population, and a smaller proportion of highly educated workers. But the productivity of farm workers, measured in terms of fall crops (rice) purchased by the government per farmer or per hectare of irrigated land, did not decline despite the loss of these youths and of human capital. The kun having had a large out-migration had a larger proportion of the population in the farm sector and a smaller proportion in the service sector. The kun having had a large out-migration also had a lower income measured in terms of the proportion of households receiving welfare payments or the amount of provincial taxes paid per household. The lower incomes of these kuns might explain why the kuns that experienced a large out-migration had difficulty in mechanizing farming. Our policy suggestions based on the tests of the currently prevailing hypotheses are as follows: 1) The main cause of farming difficulties is not a lack of human capital, but the in­crease in production costs due to rural wage increases combined with depressed farm output prices. Therefore, a more effective way of helping farm economies is by increasing farm output prices. However, we are not sure whether an increase in farm output prices is desirable in terms of efficiency. 2) It might be worthwhile to attempt to increase the size of farmland holdings per farm household so that the mechanization of farming can be achieved more easily. 3) A kun with large out-migration suffers a deterioration in income and welfare. Therefore, the government should provide a form of subsidization similar to the adjustment assistance provided for international trade. This assistance should not be related to the level of farm output. Otherwise, there is a possibility that we might encourage farm production which would not be profitable in the absence of subsidies. 4) Government intervention in agricultural research and its dissemination, and large-scale social overhead projects in rural areas, carried out by the Korean government, might be desirable from both efficiency and equity points of view. Government interventions in research are justified because of the problems associated with the appropriation of knowledge, and government actions on large-scale projects are justified because they required collective action.