• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4356-4371
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• 2014

When the load in a multi-cell orthogonal frequency division multiple access (OFDMA) system is allowed to excessively increase in face of frequent handover, the cell area becomes smaller than the designed size, and thus continuity of quality of service (QoS) for handover requests cannot be guaranteed. To efficiently support the mobility of a mobile terminal (MT), we should adaptively cope with the resource demand of handover calls. This paper proposes a twofold resource-reservation scheme for OFDMA systems to guarantee continuity of QoS for various mobile multimedia services during MT handover from lightly to heavily loaded cells. Our twofold scheme attempts to guarantee service continuity for handover and to maximize resource allocation efficiency. We performed a simulation to evaluate our scheme in terms of outage probability, handover failure rate, total throughput, and blocking rate.

• ETRI Journal
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• v.44 no.4
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• pp.531-542
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• 2022

With the increasing demand for unlicensed spectrum, several regulators have been opening up the 6-GHz band for unlicensed use while ensuring compliance with the technical requirement to avoid harmful interference in the existing primary services (PSs). In this paper, we present two methodologies, a channel-based method and a frequency-based method, which are applicable to a frequency coordination system that calculates the permissible transmit power in the channels or frequencies available to a secondary service (SS). In addition, we have demonstrated that the available transmit power of an SS can be maximized by adjusting the power allocation of the assigned resource units under the condition that the channel of the SS is partially overlapped with that of the PS. Based on the analysis results, it is suggested that it would be better to utilize the two methods selectively according to the operating channel conditions of the PS and the SS.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.789-795
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• 2014

In a demand response (DR) market run by independent system operators (ISOs), load aggregators are important market participants who aggregate small retail customers through various DR programs. A load aggregator can minimize the allocation cost by efficiently allocating its demand response resources (DRRs) considering retail customers' characteristics. However, the uncertain response behaviors of retail customers can influence the allocation strategy of its DRRs, increasing the economic risk of DRR allocation. This paper presents a risk-based DRR allocation method for the load aggregator that takes into account not only the physical characteristics of retail customers but also the risk due to the associated response uncertainties. In the paper, a conditional value-at-risk (CVaR) is applied to deal with the risk due to response uncertainties. Numerical results are presented to illustrate the effectiveness of the proposed method.

• Environmental and Resource Economics Review
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• v.9 no.2
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• pp.311-332
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• 2000

The main aim of this paper is to estimate the change in the quantity demanded of public water when the economic factors such as income and water price are changed. The privious methods to estimate the quantity of public water demanded has been usually based on the LPCD(liter per capita per day). Implicitly, this method regards the price of water as given. If the water price and income elasticities of water demand are estimated using the time-series and pooled data analysis. In the second step, the quantity demanded of public water are forecasted using the estimated elasticities. The results show that we can reduce the quantity demanded of residential water considerably when the water price is changed.

• Environmental and Resource Economics Review
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• v.14 no.4
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• pp.839-866
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• 2005

This study addresses the effects on the economy of atomic sector's R&D by considering how much KAERI's R&D expenditures in 2000 affect on the production and value-added of each industry and the whole economy. This study answers to the question using competitive import input-output tables and both supply driven and demand driven IO models, which are frequently employed in evaluating economic impacts of R&D in both domestic and foreign academic areas.

• Journal of Family Resource Management and Policy Review
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• v.7 no.1
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• pp.153-167
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• 2003

The purposes of this study were to examine the pattern of housewives’social activity participation and investigate the characteristics of this pattern. The data of this study were collected from 340 housewives living in Seoul area. Statistical methods used were frequency, percentage, oneway ANOVA, DMR-test, and cluster analysis. The results of this study were as follows; 1) 52.6% of respondents participated in social education, only 20.8％ in volunteer work. And a large number of housewives(77.6% of respondents) wanted to get a job. 2) Housewives were classified into job-demand group, job-apathy group and social activity oriented group by the pattern of social activity participation. And these groups were differed by Age, income, degree of satisfaction as a housewife, time constraints, and money constraints.

• Environmental and Resource Economics Review
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• v.11 no.4
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• pp.525-556
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• 2002

This paper investigates effect of gasoline price liberalization on price elasticity of gasoline demand. By using a model where a consumer optimizes her gasoline consumption and number of visits to gas station, we derive price elasticity of gasoline demand and its response to variation of size and frequency in price changes. It shows that price elasticity is decreased with increase in the size and frequency when the price rises. Since price liberalization increases the frequency but reduces the size, the effect of the liberalization on the price elasticity may not be determined. However, price liberalization can make the elasticity higher when the size reduction effect exceeds the frequency increase effect, which is consistent with empirical evidence provided by existing studies.

• Environmental and Resource Economics Review
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• v.10 no.1
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• pp.45-64
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• 2001

This paper estimates the gasoline price elasticities of demand for automobile fuel efficiency in Korea to examine indirectly whether the government policy of raising fuel prices is effective in inducing less consumption of fuel, relying on a hedonic technique developed by Atkinson and Halvorsen (1984). One of the advantages of this technique is that the data for a single year, without involving variation in the price of gasoline, is sufficient in implementing this study. Moreover. this technique enables us to circumvent the multicollinearity problem, which had reduced reliability of the results in previous hedonic studies. The estimated elasticities of dam and for fuel efficiency with respect to the price of gasoline, on average, is 0.42.

• Journal of Family Resource Management and Policy Review
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• v.10 no.3
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• pp.1-21
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• 2006

The purpose of this study was to examine the variables which account for grandchildren caregivers' subjective well-being. The subjects of this research were 100 grandmothers who are currently caring for grandchildren. The instruments used for this study were 'Job Content Questionnaire' by Karasek(1979), 'Family Support Inventory for Worker' by King, Mattimore, King, & Adams(1995), 'Social Support Scale' by Park(1985) and 'Psychological Positive Functioning' by Ryff(1989). Data was analyzed by descriptive statistics, Pearson's correlations and hierarchical multiple regression. The major results of this study are as follows; First, grandchildren caregiving's demand level was negatively related to grandmothers' subjective well-being, but it's control and support level were positively related to them. Second, the variables that explained grandchildren caregivers' sutjective well-being were their marital status, income, material reward, and family support. When they had a husband, the more money they had, and with more rewards for caregiving plus family support given, the more positive subjective well-being they had.

• Environmental and Resource Economics Review
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• v.1 no.1
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• pp.1-25
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• 1991

The domestic liquefied natural gas project has been carried out as a national energy scheme since the late 1980's in Korea. The natural-gas supply for civilian demand is limited to the Kyung-In area. In addition, seven major city gas corporations which now participate in the project occupy the monopolistic service area. In this study, objective cost evaluation criteria for gas distribution and an improved proposal in the evaluation method are suggested. They will go forward in solving the problems to promote demand and prevent excess profit or deficit according to the physical characteristics of the monopolistic service area.