• Journal of the Economic Geographical Society of Korea
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• v.17 no.3
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• pp.538-553
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• 2014

The aim of this study is to consider the degree of supply-demand balance in relation to the characteristics of retail sale activities in depopulation aging regions and the degree of aging by using simple regression analysis. The major findings of this study are as follows. While aging society, and aged society regions show a similar major retail sale industries, super-aged society shows fewer major industries and different industry composition. These characteristics are seen by different phenomenon and the background of the particular retail structure. The first one is that the number of employees per establishment increases when the aging phenomenon is not accelerated, and the annual sales per capita purchasing power decrease because their purchasing power becomes lower when the aging phenomenon is severe, but it also shows a high density of establishments because disperse location of establishment within depopulation aging region. The second one is the retail structure with high labor productivity in a aged and superaged society region. We identify the extent of demand and supply in general retails, fuel retails, food and beverage, and tobacco retails which represent the highest sales rates in depopulation aging region. As a result, general retails are seen as 'supply-demand balance region' in aged and super-aged society, fuel retail sales in aged and super-aged society which generally shows less sales, and food and beverages, and tobacco retails in super-aged society. The higher the degree of aging is, the less the regional differences in the gap between demand and supply is. This is because the difference in purchasing power between these regions is small.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.357_358
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• 2009

According to the 4th BPE(Basic Plan for long-term Electricity Supply and Demand), Electricity demand of Jeju island in 2012 will be reached to 682MW. Jeju island will be faced with severe shortage of electricty, also needed to find transport route to supply green energy which will be made from "Carbon free island" energy policy toward land at that time. For that reason, The plan which construct 400MW size HVDC connection line was decided for potential supply stabilization and transportation of green energy. KEPCO organized special construction office not only to observe the successful project completion which aims 2011 December but also to build up professional manpower. KEPCO is putting spur to the HVDC project these days. Construction site of converter stations has been already confirmed and contracts of cable, converter have done as per turn-key early this year. On this report, we would like to discuss about project scheme, main characteristics of system, and the furture progress plan of "Jindo~Jeju HVDC construction project expecially converter station part" which is being pushed by KEPCO.

• Korean System Dynamics Review
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• v.3 no.1
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• pp.79-104
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• 2002

A system dynamics project is going on for forecasting automobile market in Korea. The project is made up of three stages, and the first stage has been wrapped up. As the first attempt, most efforts have been focused on the sound foundation rather than the exact forecast. The model consists of three sectors; the supply sector, the demand sector, and the population sector. The supply sector is a simple stock and flow diagrams representing the supply capacities of all automobile types. The major effort is made on the demand sector and the population sector. The demands are divided into three categories; replacement demands, new demands, and additional demands. The model applies “one car per person" concept, and assumes there will be no additional demands for a while. The replacement demands are calculated based on a simple stock and flow diagram. The new demands are calculated via Bass models; each bass model represents a diffusion for each age group. The population is divided into 101 age groups (age 0 to age 100). The model has been calibrated with past 10 year data (1990 - 1999), and tested for the next two years (2000-2001). The results ware acceptable, although a fine tuning is required. Now the second stage is going on, and most of efforts are made how to incorporate the economic and cultural factors.

• Journal of Power Electronics
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• v.15 no.5
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• pp.1227-1234
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• 2015

The efficient electric power demand management in electric power supply industry is currently being changed by distributed generation. Meanwhile, small-scale distributed generation systems using renewable energy are being constructed worldwide. Several small-scale renewable distributed generation systems, which can supply electricity to the grid at peak load of the grid as per policy such as demand response programs, could help in the stability of the electric power demand management. In this case, the power quality of the small-scale renewable distributed generation system is more significant. Low prices of power semiconductors and multilevel inverters with high power quality have been recently investigated. However, the conventional multilevel inverter topology is unsuitable for the small-scale renewable distributed generation system, because the number of devices of such topology increases with increasing output voltage level. In this paper, a single-phase multilevel inverter based on H-bridge, with DC_Link divided by bi-directional switches, is proposed. The proposed topology has almost half the number of devices of the conventional multilevel inverter topology when these inverters have the same output voltage level. Double Fourier series solution is mainly used when comparing PWM output harmonic components of various inverter topologies. Harmonic components of the proposed multilevel inverter, which have been analyzed by double Fourier series, are compared with those of the conventional multilevel inverter. An inverter prototype is then developed to verify the validity of the theoretical analysis.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.3
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• pp.100-114
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• 1996

Besides insufficient water, water contamination confronts us with 'water crises' of both quantity and quality. However, the daily water consumption per capita of Korea is greater than that of other developed countries. Because of the current low water price, which is lower than a half of production cost, not only does it become difficult to cope promptly with rapidly increasing water demand and water contamination, but it also causes waste of water. We should, therefore, switch over from supply side management-oriented policy to demand side management-oriented policy through a raise of the water rate. This study carries out a cost analysis based on fair return method which is the principle of water pricing in Korea, and it estimates, through equilibrium analysis, long run marginal cost(LRMC), which satisfies allocative efficiency and reflects true social cost to additional one-unit water supply. Based on the results, this study proposes that the estimated LRMC is the optimal price level in water pricing, which is the most important of the demand side management policies. In the end, water conservation effect, price pervasive effect, and social welfare effect are analyzed.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1991.10a
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• pp.357-365
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• 1991

Military material-supply problem is one of the most important logistic problems under conscription system. Formally, two approaches were followed lowed to this problem. (1) Needs for material per soldier is estimated by past experience. The total demand for the material is estimated by multiplication of this coefficient and the number of soldiers given in the governmental programme. (2) The total demand for the material is estimated by the forcast based on the past statistics. The material supply system based on these estimates, however, relies too much on past statistics ;lack of flexibility is feared to adapt itself to changes in conscription programme, life-time of materials and so on. In this paper, the author has followed new approach : The conscription system itself is a linear input-output system, in which sequences of enlistment and dischargement are regarded as input and output. And the sequencial demands for the material are related by another linear transformation to the former sequences. In this regard z-transformation is applied to construct to transfer functions associated with this system. With these transfer functions, methods are established to determine the material demand corresponding to conscription programme and life-time distribution. Numerical methods by computers are also prepared.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.185-185
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• 2023

Agricultural water demand is considered as the major sector of water withdrawal due to irrigation. The majority part of the global agricultural field depends on various irrigation techniques. Therefore, a timely and sufficient supply of water is the most important requirement for agriculture. Irrigation is implemented in different ways in various land surface models, it can be modeled empirically based on observed irrigation rates or by calculating water supply and demand. Certain models can also calculate the irrigation demand as per the soil water deficit. In these implementations, irrigation is typically applied uniformly over the irrigated land regardless of crop types or irrigation techniques. Whereas, the latest version of Community Land Model (CLM) in the Community Terrestrial Systems Model (CTSM) uses a global distribution map of irrigation with 64 crop functional types (CFTs) to simulate the irrigation water demand. It can estimate irrigation water withdrawal from different sources and the amount or the areas irrigated with different irrigation techniques. Hence, we set up the model for the simulation period of 16 years from 2000 to 2015 to analyze the global irrigation demand at a spatial resolution of 1.9° × 2.5°. The simulated irrigation water demand is evaluated with the available observation data from FAO AQUASTAT database at the country scale. With the evaluated model, this study aims to suggest new sustainable scenarios for the ratios of irrigation water withdrawal, high depending on the withdrawal sources e.g. surface water and groundwater. With such scenarios, the CFT maps are considered as the determining factor for selecting the areas where the crop pattern can be altered for a sustainable irrigation water management depending on the available withdrawal sources. Overall, our study demonstrate that the scenarios for the future sustainable water resources management in terms of irrigation water withdrawal from the both the surface water and groundwater sources may overcome the excessive stress on exploiting the groundwater in major river basins globally.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.10
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• pp.580-587
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• 2016

This study aims to estimate the values of freshwater ecosystem services from demand and supply perspectives. From demand side, unit-values of ecosystem services are derived from Environmental Valuation Information System (EVIS) and aggregated to 5 main watersheds in Korea. The derived unit-values are based on the willingness to pay estimates per household from stated preference methods. The nation-wide average total values of water quantity supply, water purification, and natural disaster control are estimated as 501.2, 410.4, and 242.4 billion won/year, respectively. From supply side, we examine the direct and indirect public expenditures (or investment) in 2013 to improve freshwater ecosystem services by the government. The total sum of government expenditures corresponds to 8,882 billion won in 2013, where 12.9, 81.3, 0.3 and 5.3% are spent to improve provisioning, regulating, supporting and cultural services, respectively, indicating that most efforts are concentrated in enhancing regulating services.

• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.178-187
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• 2011

National water supply, water resources available, the ratio of water supply to total water resources, and the ratio of water supply to available water resources were investigated to find global seawater desalination plant market for 163 nations. Water resources available per capita from 2007 to 2016, population in water scarcity region from 2011 to 2016, and the ratio of water scarcity population to total population were also analyzed for the countries. Annual percentage increase in total municipal drinking water capital expenditure and Annual percentage increase in total industrial water market were analyzed to predict the amount of water supply by use. 76 countries are suffering from water scarcity and 60 countries among the countries have coastal regions. Forty countries were selected by considering the considerable amount and highly increasing trend of water demand by use. Most countries show increasing trend of industrial water and 82 countries have more than 4% annual increasing rate for domestic water expense from 2008 to 2016 among 163 countries. Among the 76 water scarcity countries 16 countries were finally selected by considering expense prediction by use. Middle-east, east asia, pacific ocean, and west europe regions include most selected countries.

• Journal of the Korean housing association
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• v.21 no.3
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• pp.125-134
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• 2010

The purpose of this study is to estimate the housing demands in order to address a suitable housing policy for a metropolitan city of Daegu in South Korea. Although the population of Daegu declines, a number of households increase since a number of people per households decrease. Currently a household with four people is a main housing type, however it is expected that a household with one or two increase. In 2017, a household with one will be dominant. Estimating housing sizes and their demand, the households below $60\;m^2$ gradually decline while those over $85\;m^2$ is expected to rise. Nevertheless, the demands for the house below $60\;m^2$ in its size increase at 39.2 per cent. Currently a house with $60\;m^2$ is being constructed. In particular, that of $85\;m^2$ gradually increases. The current trends may result in the widening gaps between the household demand and supply of Daegu. Therefore, it is recommended that relevant local authorities and developers should consider providing various house sizes by taking the current housing demand of Daegu into account.