• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.2
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• pp.97-106
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• 2006

Site index is an essential tool to estimate forest productivity. Generally, a site index equation is developed and used from the relationship between stand age and dominant tree heights. However, there is a limit to the use of the site index equation in the application of variable ages, environmental influence, and estimation of site index for the unstocked forest. Therefore, it has been attempted to develop a new site index equation based on various environmental factors including site, climate, and topographical variables. This study was conducted to develop a site index equation based on the relationship between site index and environmental factors for the species of Pinus koraiensis in Yangpyung-Gun, Gyunggi Province. The influence of climatic factors (temperature and solar irradiation ratio), topographical factors (elevation, slope, ratio of slope to valley and aspect) and soil profiles (soil depth by layer and soil consistency) on site index were evaluated by multiple regression analysis. Five environmental factors were selected in the final site index equation for Pinus koraiensis. The site index equation developed in this study was also verified by three evaluation statistics: model's estimation bias, model's precision, and mean square error of measurement. Based on the site index equation, the number of productive areas for Pinus koraiensis were estimated by applying GIS technique to digitized forest maps. In addition, the distribution of productive areas was compared with the areas of current distribution of Pinus koraiensis. It is expected that the results obtained in this study could provide valuable information about the amount and distribution of productive areas for Pinus koraiensis reforestation.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.4
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• pp.635-641
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• 2021

This paper aims to find out the main factors that are important in determining the size of investment in the Jordanian productive sectors. For this purpose, the study used panel data for four Jordanian productive sectors over the period 2000-2017. Also, fixed-effects modeling was carried out to identify the relationship between investment and its potential determinants. Empirical investigations of the four productive sectors reveal the following results: The real value of sector's production and the real value of credit facilities have a positive and significant impact on investment, while the real interest rate has a negative effect on investment in the Jordanian productive sectors. Also, at the sector level, agriculture was more responsive to changes in the real value of credit facilities, while other sectors were more responsive to changes in the real value of sector's production. According to these results, it seems that some policy actions should be taken to enhance the size and the role of investment in the economy. For example, policymakers should adopt a mixed policy and expand the provision of credit facilities, especially to the agricultural sector, to enhance agricultural activity in a manner that ensures the improvement of infrastructure and land reclamation.

• Research in Community and Public Health Nursing
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• v.21 no.1
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• pp.128-138
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• 2010

Purpose: This study was to identify the relation between productive activity and physical and psychological ability in elders. Methods: A total of 294 subjects aged between 60 and 92 were selected through convenient sampling. Data were collected with a self-reported questionnaire from May to June, 2008. Collected data were analyzed by SPSS/PC Win. 15.0. Results: Of variance in productive activity, 13.3% was explained by house ownership, number of diseases, and successful aging. Of variance in physical and psychological ability, 25.4% was explained by house ownership, perceived health, number of diseases, and successful aging. The correlation coefficient between productive activity and physical and psychological ability was significant (r=.32, p<.001) Conclusion: Findings of this study may be useful in understanding the health status of community-dwelling elders and developing more specific health promotion programs.

• Korean Journal of Adult Nursing
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• v.21 no.4
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• pp.423-434
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• 2009

Purpose: This study was conducted to evaluate successful aging (SA) in elderly individuals and to determine the factors that influence SA. Methods: The subjects included 207 elderly individuals from D city, Korea. The data were obtained between July 1 and August 30, 2008. The participants were assured of anonymity and confidentiality. For the evaluation, Kim & Shin's SA scale, Lawton's instrumental activities of daily living (IADL) scale, Jon's self-esteem scale, Kee's geriatric depression scale short form-Korean (GDSSF-K), and Hong's productive activities scale were used. The data were analyzed using descriptive statistics, the t-test, analysis of variance (ANOVA), and Pearson correlation coefficients; multiple regression analysis was performed using the SPSS/WIN 10.0 program. Results: The maximum score for SA was 34, and the mean score was 22.62. It was found that SA was significantly correlated to IADL, self-esteem, depression, and productive activity. Depression was the most powerful predictor of SA and it accounted for 40.6% of the total variance in SA. Self-esteem, productive activity, living situation, economic status, and age together accounted for 62.1% of the total variation in SA. Conclusion: Depression, self-esteem, and productive activity were identified as variables that influence SA. On the basis of these results, we conclude that nurses should assist elderly individuals in order to facilitate SA. Moreover, individualized nursing management strategies must be developed in order to facilitate SA.

• Journal of Korean Society of Forest Science
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• v.103 no.4
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• pp.605-612
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• 2014

This study was conducted to predict the changes of yearly productive area distribution for Quercus mongolica under climate change scenarios. For this, site index equations by ecoprovinces were first developed using environmental factors. Using the large data set from both a digital forest site map and a climatic map, a total of 48 environmental factors including 19 climatic variables were regressed on site index to develop site index equations. Two climate change scenarios, RCP 4.5 and RCP 8.5, were then applied to the developed site index equations and the distribution of productive areas for Quercus mongolica were predicted from 2020 to 2100 years in 10-year intervals. The results from this study show that the distribution of productive areas for Quercus mongolica generally decreases as time passes. It was also found that the productive area distribution of Quercus mongolica is different over time under two climate change scenarios. The RCP 8.5 which is more extreme climate change scenario showed much more decreased distribution of productive areas than the RCP 4.5. It is expected that the study results on the amount and distribution of productive areas over time for Quercus mongolica under climate change scenarios could provide valuable information necessary for the policies of suitable species on a site.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.1
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• pp.72-82
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• 2014

This study was conducted to predict the changes of yearly productive area distribution for pinus densiflora under climate change scenario. For this, site index equations by ecoprovinces were first developed using environmental factors. Using the large data set from both a digital forest site map and a climatic map, a total of 48 environmental factors including 19 climatic variables were regressed on site index to develop site index equations. Two climate change scenarios, RCP 4.5 and RCP 8.5, were then applied to the developed site index equations and the distribution of productive areas for pinus densiflora were predicted from 2020 to 2100 years in 10-year intervals. The results from this study show that the distribution of productive areas for pinus densiflora generally decreases as time passes. It was also found that the productive area distribution of Pinus densiflora is different over time under two climate change scenarios. The RCP 8.5 which is more extreme climate change scenario showed much more decreased distribution of productive areas than the RCP 4.5. It is expected that the study results on the amount and distribution of productive areas over time for pinus densiflora under climate change scenarios could provide valuable information necessary for the policies of suitable species on a site.

• Communications of Mathematical Education
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• v.38 no.3
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• pp.309-330
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• 2024

This study analyzed the productive struggles experienced by the sixth-grade elementary school students when productively overcoming the struggles they encountered during mathematical problem-solving. By analyzing their processes of solving multi-strategic and open-ended problems, productive struggles were categorized according to two steps of problem-solving. Additionally, we examined the factors that support students in overcoming these struggles, distinguishing between individual, peer, and teacher influences. The study identifies four types of productive struggles during the problem-understanding step and six during the plan devising and carrying-out step. In the problem-understanding step, the most prevalent type involved overcoming difficulties to grasp the elements and conditions of the problem, while in the plan devising and carrying-out step, persistence in problem-solving was the most common. The factors supporting productive struggles were ranked in order of influence: individual, peer, and teacher support. Teacher support played a significant role during the problem-understanding step, whereas individual and peer supports were more influential during the plan devising and carrying-out step. Based on these findings, the study offers some didactical implications for understanding the characteristics of productive struggles and strategies for effectively supporting students through the problem-solving process.

• Journal of Korean Society of Forest Science
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• v.102 no.3
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• pp.437-445
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• 2013

This study was conducted to develop site index equations and to estimate productive areas of Quercus acutissima by ecoprovince in Korea using environmental factors. Using the large data set from both a digital forest site map and a climatic map, a total of 48 environmental factors including 19 climatic variables were regressed on site index to develop site index equations. Four to six environmental factors for Quercus acutissima by ecoprovince were selected as independent variables in the final site index equations. The result showed that the coefficients of determination for site index equations were ranged from 0.30 to 0.41, which seem to be relatively low but good enough for the estimation of forest stand productivity. The site index equations developed in this study were also verified by three evaluation statistics such as the estimation bias of model, precision of model, and mean square error of measurement. According to the evaluation statistics, it was found that the site index equations fitted well to the test data sets with relatively low bias and variation. As a result, it was concluded that the site index equations were well capable of estimating site quality. Based on the site index equations of Quercus acutissima by ecoprovince, the productive areas by ecoprovince were estimated by applying GIS technique to the digital forest site map and climate map. In addition, the distribution of productive areas by ecoprovince was illustrated by using GIS technique.

• Journal of Korean Society of Forest Science
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• v.101 no.3
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• pp.395-404
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• 2012

This study was conducted to develop site index equations and to estimate productive areas for major coniferous species in Korea such as Pinus densiflora Sieb. et. Zucc, Pinus densiflora for. erect, Larix leptolepis and Pinus koraiensis using environmental factors. Using the large data set from both a digital forest site map and a climatic map, a total of 43 environmental factors including 15 climatic variables were regressed on site index by tree species to develop site index equations. Six environmental factors by species were selected as independent variables in the final site index equations. The result showed that the coefficients of determination for site index equations by species were ranged from 0.36 to 0.56, which seem to be relatively low but good enough for the estimation of forest stand productivity. The site index equations developed in this study were also verified by three evaluation statistics such as the estimation bias of model, precision of model, and mean square error of measurement. According to the evaluation statistics, it was found that the site index equations by species fitted well to the test data sets with relatively low bias and variation. As a result, it was concluded that the site index equations by species were well capable of estimating site quality. Based on the site index equations, the productive areas by species for all forest areas were estimated by applying GIS technique to the digital forest site map and climate map. In addition, the distribution of productive areas by species was illustrated by using GIS technique.

• The Journal of Fisheries Business Administration
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• v.43 no.1
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• pp.11-18
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• 2012

This study is aimed to estimate a dynamic productive efficiency by vessel of large purse seine fishery and analyze changes of them over times using a window/DEA method. In addition, based on estimation results, it aims to suggest production management implications for an viable development of fisheries. Results indicated that an annual efficiency change of large purse seine fishery was estimated at 0.77 for 2007~2008, 0.83 for 2008~2009, and 0.77 for 2009~2010, showing a decreasing trend. As returns on sales of vessels of large purse seine fishery showed a decreasing trend, the degree of efficiency of a vessel might be closely related to the fishing profitability. The Window/DEA method was used in this study to estimate the efficiencies of vessels for large purse seine fishery. This method is well known and widely used to analyze the dynamic efficiency and it can provide useful implications for management of input factors. As a limitation of this study, it was not able to provide detailed management ways to reduce inefficiencies. However, they can be investigated with data on managerial factor, human factor, distribution factors as a future study.