• International Journal of Highway Engineering
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• v.7 no.2 s.24
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• pp.77-86
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• 2005

A spalling model for jointed connote pavements(JCP) was developed using the data of distresses, climates, and materials at the sections of long-term pavement performance(LTPP) investigation. The total of forty-four spatting distress data was collected at twenty-two JCP LTPP sections in 1999 and in 2004. In addition, the data of climates, geometric shapes of the slabs, and material properties was also collected at those times. Factors significantly influencing the spalling distress were found by a sensitivity analysis for the data. Consequently, a spatting model was developed by a multi-regression analysis for the factors. The model showed reasonable trend of the spatting development comparing to other foreign models.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.110.1-110.1
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• 2011

This study analyzed the performance of long term operation photovoltaic system The 50 kWp grid connected photovoltaic system which was installed at KEPRI site in 1999 has been operated more than 12 years. In order to acquire long term operation characteristics of medium size photovoltaic system, the operation test data related on power generation electricity and capacity factor of 50 kWp system, which have been collected since 1999, were analysed. From the analysing results, 57.7 MWh in annual power generation electricity of 50 kWp photovoltaic system in 1999 has been decreased 49.1 MWh in 2005 and reached 38.0 MWh in 2010. In addition to, the capacity factor of 50 kWp photovoltaic system also showed 13.2 % in 1999, 11.2% in 2005 and finally reached 8.8% in 2011. The operation test data showed a trend of decreasing of generation electricity and capacity factor during the 12 years operation time and we guessed that was caused by solar cell performance degradation and decreasing of PCS system efficiency.

• Korean Journal of Agricultural Science
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• v.25 no.1
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• pp.41-51
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• 1998

This study not only carried out to grasp about the sununarized characteristics of the relationship between international timber market and production trend of wood products, but also focused on the analysis of korean wood demand and the long-term forecast with econometric analysis. The result of regression analysis for wood demand in Korea is that coniferous roundwood demand(CIWD) is explained by coniferous foreign roundwood price(CWRI), Gross domestic product(GDP), a dummy variable. Non-coniferous roundwood demand(NCIWD)is explained by non-coniferous roundwood price(NCWRI), coniferous roundwood price(CWRI), a dummy variable. As the result of long-term forecast by base case, the total roundwood demand was forecasted $11,107,000m^3$ in the year 2000, $11,781,000m^3$ in 2005, $12,565,000m^3$ in 2010. As the result of scenario 1, total roundwood demand was forecasted $11,027,000m^3$ in 2000, $11,435,000m^3$ in 2005, $11,952,000m^3$ in 2010. And as the result by scenario 2, total roundwood demand was forecasted $11,341,000m^3$ in 2000, $12,208,000m^3$ in 2005 $13,257,000m^3$ in 2010.

• Journal of Environmental Science International
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• v.16 no.12
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• pp.1411-1424
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• 2007

Long-term trends and distribution patterns of water quality were investigated in the Asan coastal areas of Yellow Sea, Korea from 1975 to 2005. Water samples were collected at 3 stations and physicochemical parameters were analyzed including water temperature, salinity, suspended solids(SS), chemical oxygen demand(COD), dissolved oxygen(DO) and nutrients. Spatial distribution patterns were not clear among stations but the seasonal variations were distinct except COD, SS and nitrate. The trend analysis by principal component analysis(PCA) during twenty years revealed the significant variations in water quality in the study area, Annual water qualities were clearly discriminated into 4 clusters by PCA; year cluster 1988-1991, 1994-1997, and 1992-1993/1998-2005. By this multi-variate analysis we can summarize the annual trends as the followings; salinity, suspended solids and dissolved oxygen tended to increase from late 1980's, increased pH and COD from 1992, and decreased salinity and increased nitrogen and COD from 1990 due to the runoff frow agricultural lands causing eutrophication.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1468-1471
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• 1999

This paper presents a method of the regional long-term distribution planning considering economic indicator with the assumption that energy demands proportionally increases with the economic indicators. For the practical distribution planning, it is necessary to regional load forecasting, distribution substation planning, distribution feeder planning. Accordingly, in this paper, after performing regional load forecasting considering economic indicator, it is performed distribution substation planning and distribution feeder planning in order by using this result. For accurate distribution planning, it is very important to scrutinize the correlation among the regional electric power demands, economic indicator and other characteristics because distribution planning results may vary depending on many different factors such as electric power demands, gross products, social trend and so on. In this paper, various steps microscopically and macro scopically are used for the regional long-term distribution planning in order to increase the accuracy and practical use of the results

• Journal of East-West Nursing Research
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• v.25 no.2
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• pp.157-165
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• 2019

Purpose: This study aims to provide basic data for the development of measures and promoting home health nursing by examining the current status and trends in home health nursing for long-term care (LTC) insurance beneficiaries. Methods: Secondary data, including annual LTC insurance statistics reports for 2010-2017 and LTC manpower data, were used to compute current status and trends in the provision of home health nursing. Results: Beneficiaries of home health nursing under LTC insurance, insurance-covered costs for home health nursing, home health nursing provider, and home health nursing providing institution only accounted for 3% of all insurance-covered home care services, and were on a consistent decline since 2010. In particular, vulnerable rural regions with high proportion of individuals had poor infrastructure in terms of home health nursing institutions and manpower, but had a higher home health nursing utilization rate compared to urban regions. Conclusion: In addition to measures to support home health nursing service beneficiaries, policy measures are needed to support home health nursing service personnel and institutions. Furthermore, programs to cultivate the expertise of home health nurses and improve quality of home health nursing services should be developed in order to promote home health nursing utilization in vulnerable rural regions.

• Journal of Environmental Science International
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• v.33 no.3
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• pp.227-234
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• 2024

We investigated the change in land-use alteration in a 45 km × 45 km area around the Upo wetlands in 1920s(before the Japanese occupation period), 1950s(immediately Korean independence) and the period 1970s to 2000s. These data can guide in understanding surface environmental changes in the lower Nakdong River from the early 20^th century to the present. The influence of the long-term decreasing trend of the wetland area at the Upo Swamp was evaluated using a high-resolution local circulation model. The cooling effect of the wetlands on surface air during the daytime in summer(e.g, early August) was approximately 2℃ greater in the 1920s than in the 2000s, which is attributed to wider water areas in the 1920s. Additionally, long-term changes in land use have caused changes in the convergence zone of local circulation wind.

• Journal of Environmental Science International
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• v.25 no.1
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• pp.107-125
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• 2016

Long-term variations of $PM_{10}$ and the characteristics of local meteorology related to its concentration changes were analyzed at 4 air quality sites (Ido-dong, Yeon-dong, Donghong-dong, and Gosan) in Jeju during two different periods, such as PI (2001-2006) and PII (2007-2013), over a 13-year period. Overall, the long-term trend of $PM_{10}$ was very slightly downward during the whole study period, while the high $PM_{10}$ concentrations in PII were observed more frequently than those in PI. The concentration variations of $PM_{10}$ during the study period was clarified in correlation between $PM_{10}$ and meteorological variables, e.g. the low (high) $PM_{10}$ concentration with large (small) precipitation or high (low) radiation and in part high $PM_{10}$ concentrations (especially, Donghong-dong and Gosan) with strong wind speed and the westerly/northwesterly winds. This was likely to be caused by the transport effect (from the polluted regions of China) rather than the contribution of local emission sources. The $PM_{10}$ concentrations in "Asian dust" and "Haze" weather types were higher, whereas those in "Precipitation", "Fog", and "Thunder and Lighting" weather types were lower. The contribution of long-range transport to the observed $PM_{10}$ levels in the urban center (Ido-dong, Yeon-dong, and Donghong-dong), if estimated by comparison to the data of the background site (Gosan), was found to explain about 80% (on average) of its input.

• Journal of the Korean earth science society
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• v.40 no.5
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• pp.487-501
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• 2019

In this study, steric height variability in the East Asian Seas (EAS) has been analyzed by using ocean reanalysis intercomparison project (ORA-IP) data. Results show that there are significant correlations between ocean reanalysis and satellite data except the phase of annual cycle and interannual signals of the Yellow Sea. Reanalysis ensemble derived from 15-different assimilation systems depicts higher correlation (0.706) than objective analysis ensemble (0.296) in the EAS. This correlation coefficient is also much higher than that of the global ocean (0.441). For the long-term variability of the thermosteric sea level during 1993-2010, a significant warming trend is found in the East/Japan Sea, while cooling trend is shown around the Kuroshio extension area. For the halosteric sea level, a dominant freshening trend is found in the EAS. However, below 300 m depth around this area, the signal-to-noise ratio of the linear trend is generally less than one, which is related to the low density of observation data.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.4
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• pp.353-360
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• 2010

The result of analysis of the observed temperature data by the Serial Oceanography Investigation of National Fisheries Research and Development Institute (NFRDI) during last 41 years from 1969 to 2008 showed that sea surface temperatures in the East, West and South Sea of Korea were clearly increased. In case of 100m depth, temperature was increased in the South Sea of Korea, but it was decreased in the East Sea. Especially, the temperature around the coastal area in the East Sea was significantly decreased by the spatial distribution of long-term change of temperature on 100m depth. It should lead to the decreasing trend in the long-term change of temperature on 100 m depth in the entire East Sea. The increasing trend was clearly larger in wintertime than in summertime by a factor of about 2 It means that the long-term increasing trend of sea surface temperature in the Korean Waters is usually caused by the distinctive increasing trend in wintertime. As the results of the analysis of air temperature and wind speed on the 6stations around the coastal area in the Korean Waters, air temperature was found to be continuously increased, but wind speed to be gradually decreased in winter. The weakness of vertical mixing by decreasing of wind speed caused to make the surface mixed layer shallow. it could be considered that the increasing trend of surface temperature was caused by weak mixing between surface and intermediate layers.