• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.184-184
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• 2017

A nation-wide water-energy-food (WEF) nexus simulation model has been developed by the authors and successfully applied to South Korea to predict the sustainability of those three resources in the next 30 years. The model was also capable of simulating future scenarios of resources allocation based on priority rules aiming to maximize resources sustainability. However, the process was still relying on several assumptions and trial-and-error approach, which sometimes resulted in non-optimal solutions of resources allocation. In this study, an optimization module was introduced to enhance the model in generating optimal resources management rules. The objective of the optimization was to maximize the reliability index of resources by determining the resources' allocation and/or priority rules for each demand type that accordingly reflect the resources management policies. Implementation of the optimization module would result in balanced allocation and management of limited resources and assist the stakeholders in deciding resources' management plans, either by fulfilling the domestic production or by global trading.

• Journal of the Korean Solar Energy Society
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• v.28 no.5
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• pp.49-55
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• 2008

The radiant cooling(RC) effects are studied during the winter night. The plate was viewing the nighttime sky. The data were collected at the rooftop of the Engineering building at the Dongguk University in Seoul, Korea. As observed during the summer night, the plate temperature was lower than ambient temperature under the RC favorable conditions. The parameters under study are the wind velocity, cloud index, and visibility for given system size and surface condition. The results follow the same tendency with these parameters as observed from the previous study for the summer night. As long as the wind velocity is less than around 2 m/s, the radiant cooling was observed with the system under study. In some cases, the radiant cooling temperature differences (RCTD) are higher than those for the summer night. The larger the RCTD as the wind velocity decreases and as the sky becomes clear.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.2
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• pp.135-140
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• 2021

This study introduces a new pulse width modulation (PWM) method to reduce common-mode voltages (CMVs) and then compares its performance with other reduced CMV-PWM (RCMV-PWM) methods. CMVs should be reduced to ensure the electromagnetic compatibility and safety of grid-connected inverters. RCMV-PWM methods attempt to synthesize voltage references without zero vectors, which cause high CMV peaks. In these methods, the peak-to-peak magnitude of CMVs can be reduced by one-third of the conventional space-vector PWM. The introduced method splits every reference vector into two vectors to avoid the use of zero vectors. The performances of the RCMV-PWM methods are analyzed in accordance with the modulation index through simulation and experiment.

• Journal of Climate Change Research
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• v.9 no.4
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• pp.407-421
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• 2018

In this paper, I analyze the GHG (greenhouse gas) emission factor of the domestic railway transportation sector using the LMDI (Log Mean Divisia Index) methodology. These GHG factors are the emission factor effect, energy intensity effect, transportation intensity effect, and economic activity effect. The analysis period was from 2011 to 2016, and the analysis objects were an intercity railway, wide area railway, and urban railway. The results show that the GHG emission of railway transportation sector decreased during these 6 years. The factors decreasing the GHG emission are the emission factor effect, energy intensity effect, and transportation intensity effect, while the factor increasing the GHG emission is the economic activity effect.

• Environmental and Resource Economics Review
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• v.31 no.4
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• pp.825-848
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• 2022

This paper analyzed the factors for increasing energy consumption in the domestic manufacturing sector using the LMDI (Log mean division index) decomposition method for the period from 1999 to 2019. Among the LMDI decomposition analysis methods, both additive and multiplicative factor decomposition methods were used. in this analysis. According to the result of the analysis, the factor that increased energy consumption in the domestic manufacturing industry was the production effect, and the structure effect and intensity effect were found to be the factors that decreased energy consumption. In particular, the reduction of energy consumption due to the structure effect was greater than that of energy consumption effect due to the intensity effect. By period, it can be seen that energy consumption increased rapidly due to the production effect until 2011, but after that, the increase in energy consumption due to the production effect slowed down. On the other hand, after that, the energy reduction effect due to the structure effect and the intensity effect became prominent. In order to save energy in the manufacturing sector in the future, energy diagnosis and management through EMS (Energy management system) and FEMS (Factory energy management system) are more necessary. In addition, restructuring into a low-energy consumption industry seems more necessary.

• Journal of Astronomy and Space Sciences
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• v.29 no.3
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• pp.259-267
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• 2012

Polar cap potential has long been considered as an indicator for the amount of energy flowing in the magnetosphere-ionosphere system. Thus, the estimation of polar cap potential is important to understand the physical process of the magnetosphere. To estimate the polar cap potential in the Northern Hemisphere, merging electric field by Kan & Lee (1979) is adopted. Relationships between the PC index and calculated merging electric field ($E^*$) are examined during full-time and storm-time periods separately. For this purpose Dst, AL, and PC indices and solar wind data are utilized during the period from 1996-2003. From this linear relationship, polar cap potential (${\Phi}^*$) is estimated using the formula by Doyle & Burke (1983). The values are represented as $58.1{\pm}26.9$ kV for the full-time period and $123.7{\pm}84.1$ kV for a storm-time period separately. Considering that the average value of polar cap potential of Doyle & Burke (1983) is about 47 kV during moderately quiet intervals with the S3-2 measurements, these results are similar to such. The monthly averaged variation of Dst, AL, and PC indices are then compared. The Dst and AL indices show distinct characteristics with peaks during equinoctial season whereas the average PC index according to the month shows higher values in autumn than in spring. The monthly variations of the linear correlation coefficients between solar wind parameters and geomagnetic indices are also examined. The PC-AL linear correlation coefficient is highest, being 0.82 with peaks during the equinoctial season. As with the AL index, the PC index may also prove useful for predicting the intensity of an auroral substorm. Generally, the linear correlation coefficients are shown low in summer due to conductance differences and other factors. To assess the role of the PC index during the recovery phase of a storm, the relation between the cumulative PC index and the duration is examined. Although the correlation coefficient lowers with the storm size, it is clear that the average correlation coefficient is high. There is a tendency that duration of the recovery phase is longer as the PC index increases.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.24.2-24.2
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• 2008

We have examined the relative contributions of representative space weather proxies (geomagnetic aa index) to global warming (Global temperature anomaly) and compared them with that of green house effect characterized CO2 content from 1868 to 2005. For this we used Hadcrut3 temperature anomaly (Ta) data, aa index taken at two anti-podal subauroral stations (Canberra Australia and hartland England), and the CO2 data come from historical ice core records. From the comparison between Ta and aa index, we found several interesting results: (1) the linear correlation coefficient between two parameters increases until 1990 and then decreases rapidly, and (2) the scattered plots between two parameters shows different patterns before and after 1990. A partial correlation of Ta and two quantities (aa, CO2) also shows that the geomagnetic effect (aa index) is dominant until about 1990 and the CO2 effect becomes much more important after then. These results imply that the green house effect become very important since at least 1990. For a further analysis, we simply assume that Ta (total) = Ta (aa) + Ta (CO2) and made a linear regression between Ta and aa index from 1868 to 1990. A linear model is then made from the linear regression between energy consumption (a proxy of CO2 effect) and Ta (total) - Ta (aa) since 1990. This linear model makes it possible to predict the temperature anomaly in 2030, about 1 degree higher than the present temperature, which is much larger than in the previous century.

• Imaging Science in Dentistry
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• v.34 no.2
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• pp.69-74
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• 2004

Purpose : This study was conducted to compare the radiomorphometric indices of the mandible on panoramic radiographs among three groups of normal, osteopenia and osteoporosis and to determine whether panoramic indices have validity in predicting osteoporotic risk. Materials and Methods: Ninty-four postmenupausal women aged 42-72 years (mean 62±7.5) were examined using dual energy X-ray absorptionmetry (DEXA) of the lumbar and classified into three groups by WHO classification. Panoramic mandibular index (PMI), mandibular cortical thickness (Mental index (MI), Antegonial index (AI), Gonial index (G!)) and the mandibular cortical index (MCI) were measured bilaterally on panoramic radiographs and analyzed. Results: There were signigicant differences among normal, osteopenic and osteoporoti groups in PMI (I), PMI (S), MI, AI, GI and MCI. The sensitivities of the MCI (93%) and the combination index of MCI and MI (90%) in diagnosing osteopenic/osteoporotic cases were high. Conclusion: The widths and shapes of the mandibular cortical bone on panoramic radiography may highly reflect the systemic osteopenic/osteoporotic conditions of the patients.

• Journal of the Korean housing association
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• v.25 no.2
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• pp.79-87
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• 2014

The purpose of this study is to research the characteristics of literature related to environmentally friendly for a village-focused green index. In order to make an assessment, keywords relating to green architecture were selected: environmental friendliness, ecology, sustainable, Noksaek (Green in Korean), green, and environmentally friendly. In addition, three keywords defining the scope of space were also selected: building, village, and city. Quantitative changes and contents of articles containing the keywords were analyzed. The result is as follows. First, 'sustainable' and 'ecology' were the terms most frequently used as parts of subjects and titles, respectively. Second, the studies relating to green architecture focused on villages mostly examine the actual conditions of the villages; criteria for environmental friendliness, analyses and evaluation of the environmentally friendly features of the village; and ways to establish a green, ecological, and sustainable village. Finally, when it came to establishing a village-focused green index, the environment, resources, and energy are shown to be very important elements. In addition, the term 'ecology' in a green index is shown to be significant for the management of the natural environment.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.79.3-80
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• 2016

We have investigated the correlation analysis between global temperature anomaly and two main factors: geomagnetic activity (aa index) of Earth external factor and CO2 of Earth internal factor. For this, we used NOAA Global Surface Temperature anomaly (Ta) data from 1868 to 2015. The aa index indicates the geomagnetic activity measured at two anti-podal subauroral stations (Canberra Australia and Hartland England) and the CO2 data come from historical ice core records and NOAA/ESRL data. From the comparison between (Ta) and aa index, we found several interesting things, First, the linear correlation coefficient between two parameters increases until 1985 and then decreases rapidly. Second, the scattered plot between two parameters shows a boundary of the correlation tendency (positive and negative correlation) near 1985. A partial correlation of (Ta) and two main factors (aa index, CO2) also shows that the geomagnetic effect (aa index) is dominant until about 1985 and the CO2 effect becomes much more important after then. These results indicate that the CO2 effect become very an important factor since at least 1985. For a further analysis, we simply assume that Ta = Ta(aa)+Ta(CO2) and made a linear regression between (Ta) and aa index from 1868 to 2015. A linear model is then made from the linear regression between energy consumption (a proxy of CO2 effect) and Ta-Ta(aa) since 1985. Our results will be discussed in view of the prediction of global warming.