• Environmental and Resource Economics Review
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• v.16 no.1
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• pp.99-127
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• 2007

When the margin between available capacity and demand is thin in a liberalized electricity market, prices rise steeply and system reliability is threatened. The principal response to these circumstances is often an assumption that price spikes and electricity shortages are the result of a failure to build sufficient new supplying facilities. It is, of course, often the case that additional investments in generation and network facilities would improve reliability, and such investments are often needed. But focusing on additional generation and transmission facilities for restoring balance to the grid overlooks the essential fact that reliability is a function of the relationship between supply and demand, imposing unnecessary costs on electric system. When the relationship is out of balance, the search for solutions must consider not only investments supply-side resources but also cost-effective demand-side resources such as accelerated load management, efficiency measures, and price-responsive load programs. Integrating demand resources into electricity markets can add enormous value to the electric system, widening the capacity margin, lowering costs and enhancing system reliability at the same time. This paper studies several challenges now facing electricity markets: demand-side management-especially, economic effects of demand response, potential reliability problems, market and system operation, CBP market improvements and so on. The paper concludes with a series of policy recommendations in five areas: (i) The Effects of efficient improvement to incorporate demand responses and demand-side resources into modem electricity markets, (ii) Fosteing price based demand response and (iii) improving incentive based demand response, (iv) strengthen demand response analysis and valuation, (v) integrating demand response into resource planning and adopting enabling technologies.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.1
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• pp.13-25
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• 2007

The water treatment plants in Seoul Metropolitan Area, which are under Korea Water Resources Corporation(KOWACO)'s management, take water from Paldang Reservoir in Han River System for drinking water supply. There are taste and odor (T&O) problems in the finished water because the conventional treatment processes do not effectively remove the T&O compounds. As part of countermeasures for taste and odor control, KOWACO is planning to introduce advanced water treatment process such as ozone and GAC in near future. This study evaluated the removal characteristics of T&O and dissolved organic matter (DOM) to find design and operation parameters of advanced water treatment processes in a pilot-scale treatment plant. The GAC adsorption capacity for DOC in the two GAC system (GAC and $O_3$-GAC) at an EBCT of 14min was mostly exhausted after 9months. The differency of the removal efficiency of DOC between $O_3$-GAC and GAC increased with increasing operation time because the bioactivity in $O_3$-GAC process was enhanced by post-ozone process. Removal by conventional treatment was unable to reach the target TON(threshold odor number) of 3 but GAC systems at an EBCT(empty bed contact time) of 14 min were able to archive the target with few exception. During the high T&O episodes, PAC as a pretreatment together with GAC could be useful option for T&O control. However, substantial TON removal continued for more than two year (> 90,000 bed volumes). At the spiking of less concentration 26 to 61 ng/L in the influent of GAC systems, GAC absorber and $O_3$-GAC processes could meet the treatment target. The better spike control after 12 and 19 months of operation compared to that after 7 months of operation is a strong indication of biological control. The results presented in this study had shown that $O_3$-GAC process was found to be more effective for T&O control than GAC process. And the main removal mechanism in GAC systems were adsorption capacity and biodegradation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.143-149
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• 2019

In this study, a U-shape composite beam was developed to be effectively used for a steel parking lot which is 8m or lower in height. When the U-shape composite beam was applied to a steel parking lot, essential considerations were story-height and long-span. In addition, due to the mixed structural system with reinforced concrete and steel material, the U-shape composite beam needed to have a structural integrity and reliable performance over demand capacity. The main objective of this study was to investigate the performance of the structure consisting of the reinforced concrete (RC) slab and U-shape beam. A U-shape composite beam generally used at a parking lot served as a control specimen. Four specimens were tested under four-point bending. To calculate theoretical values, strain gauges were attached to rebar, steel plate, and concrete surface in the middle of the specimens. As the results, initial yielding strength of the control specimen occurred at the bottom of the U-shaped steel. After yielding, the specimen reached the maximum strength and the RC slab concrete was finally failed by concrete crush due to compressive stress. The structural performance such as flexural strength and ductility of the specimen with the increased beam depth was significantly improved in comparison with the control specimen. Furthermore, the design of the U-shape composite beam with the consideration of flexural strength and ductility was effective since the structural performance by a negative loading was relatively decreased but the ductile behavior was evidently improved.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.6
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• pp.721-733
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• 2023

As the frequency of extreme rainfall events increase due to climate change, climate change adaptation measures have been proposed by the central and local governments. In order to reduce flood damage in urban areas, various flood response policies, such as low impact development techniques and enhancement of the capacity of rainwater drainage networks, have been proposed. When these policies are established, regional characteristics and policy-effectiveness from the cost-benefit perspective must be considered for the flood mitigation measures. In this study, capacity enhancement of rainwater pipe networks and low impact development techniques including green roof and permeable pavement techniques are selected. And the flood reduction effect of the target watershed, Gwanak campus of Seoul National University, was analyzed using SWMM model which is an urban runoff simulation model. In addition, along with the quantified urban flooding reduction outputs, construction and operation costs for various policy scenarios were calculated so that cost-benefit analyses were conducted to analyze the effectiveness of the applied policy scenarios. As a result of cost-benefit analysis, a policy that adopts both permeable pavement and rainwater pipe expansion was selected as the best cost-effective scenario for flood mitigation. The research methodology, proposed in this study, is expected to be utilized for decision-making in the planning stage for flood mitigation measures for each region.

• Journal of Korean Society of Transportation
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• v.25 no.4
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• pp.79-87
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• 2007

The interchanges of urban freeways have many problems with traffic operation due to high off-ramp flows and frequent congestion at adjacent intersections. The flow exiting from off-ramps is affected by the operational status and traffic volume conditions of the nearest signalized intersection. As a result, off-ramp flow cannot exit and the queue backs up the freeway mainline when queues from the signalized intersection form up to the junction of the off-ramp and street. The spacing between an off-ramp and an adjacent intersection is likely to determine the traffic conditions at the adjacent intersection. However, the current design guidelines do not consider such a factor. This study is to develop a model calculating the spacing between off-ramps and adjacent intersections considering the signal, traffic, and road conditions. The variables affecting the model in this study are effective green time (g/C), volume-capacity ratio (v/c), the number of lanes, and off-ramp volume. Various scenarios are designed to represent the effects of the variables and the road networks are constructed using VISSIM, which is a common traffic micro-simulation software package. The queue length is derived from VISSIM and this length is considered as the recommended spacing between the off-ramp and the adjacent intersection. Through the simulation analysis, regression models are developed to calculate the queue length reflecting the various conditions such as signals, traffic, and road configurations. The developed model can be used to create road design guidelines to determine the location of off-ramps in the planning stage.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.163-169
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• 2017

Although the strength of polyethylene terephthalate (PET) fibers which are generally used to make plastic bottles is low, the deformability of PET fibers is substantially high. Due to these material characteristics, a PET fiber can be used as a reliable strengthening material to resist a large deformation caused by earthquake and research pertinent to application of PET fibers is actively conducted in Japan. Therefore, in this study, experiments have been carried out to investigate the lateral confinement effect of PET fibers and to assess the applicability of PET fibers to construction fields by comparing the strengthening effect of PET fibers to that of carbon and glass fiber sheets. For this purpose, concrete cylinder specimens with parameters of different concrete strength and strengthening layers of carbon fiber sheets, glass fiber sheets, and PET fibers were respectively tested using two sets of cylinders for each parameter. As a result, specimens strengthened with carbon fiber sheets and glass fiber sheets failed due to sudden decrease of strength as with existing studies. However, specimens with PET fibers reached their maximum strength and then failed after gradual decrease strength without failure of PET fibers. In addition, although the strength of specimens with PET fibers did not significantly increase in comparison with that of specimens with carbon fiber sheets and glass fiber sheets, specimens with PET fibers indicated considerable deformability. Thus, a PET fiber can be considered as an effective strengthening material.

• Journal of the Korean Society of Marine Environment & Safety
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• v.10 no.2 s.21
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• pp.81-88
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• 2004

We review the adaptation strategies of the 21st climate change in an application to sea level rise. For the development of appropriate adaptation strategies on the coast vulnerable to the sea level rise, we have to consider the issues such as where to adapt, how to adapt, and when to adapt. The coastal target needed adaptation can be found by the evaluation of adaptive capacity of the coastal zone which requires the understanding of impacts and adaptive potential of the natural and socioeconomic systems in the coastal zone. Planned adaptation options to sea level rise can be classified into three generic approaches as managed retreat, accommodation, and protection In practice, the implementation of the options requires the analysis of land use, degree of vulnerability, cost and benefit, etc, and may be combination of the options rather than one approach. In terms of the response timing, the adaptation can be grouped as anticipatory and reactive ones. Generally it is more effective to consider both anticipatory and reactive adaptations at the same time for the impacts of future sea level rise. Due to the scientific uncertainty of climate change issues including sea level rise, the adaptation processes have to be designed to deal with a series of processes such as information md awareness establishment, planning and design implementation, and monitoring and evaluation in continuity and long-term period.

• Child Health Nursing Research
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• v.20 no.4
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• pp.275-282
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• 2014

Purpose: The purpose of this study was to identify effects of a maternal-child health education program for nurses in Tigray, Ethiopia. Methods: One-group pre-posttest design was used. The maternal-child health (MCH) education program was given to nurses from 5 health centers in Tigray, Ethiopia. Knowledge and confidence levels were measured before and after each education session. Data were analyzed using paired t-test. Results: The topics of the 5 educational sessions were family planning, antenatal care, care during labor, immunization, and integrated management of neonate, and child illness. Knowledge scores (1st: Z=3.931, p=.001; 2nd: Z=6.189, p <.001; 3rd: Z=5.658, p <.001, 4th: Z=8.734, p <.001, 5th: Z=14.167, p <.001) and confidence levels (1st: Z=8.467, p <.001; 2nd: Z=4.183, p <.001; 3rd: Z=4.992, p <.001) improved significantly. Conclusion: The findings of this study imply that the MCH education program for nurses was effective in developing the maternal-child health capacity of the nurses in Tigray, Ethiopia.

• Journal of the Korean association of regional geographers
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• v.18 no.2
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• pp.141-160
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• 2012

This paper evaluates the governance of the Andong International Mask Dance Festival. The evaluation focuses on mutual cross-assessment of agents engaging in governance relating to four elements: social justification, reliability, professionalism and transparency. Governance based on co-operative partnership was the essential factor leading to the mask festival's success. Governance of the Andong International Mask Dance Festival in 2011 was privately initiated governance having horizontal and open partnership among festival specialists, civil society organizations, regional business organizations, volunteers and local government, with the Andong Festival Tourism Foundation as the central figure. Three of governance elements were successfully carried through; the exception was transparency. The agents who gave more positive evaluations were those who played leading roles in planning and conducting events, as well as in assessing those events. The reasons for positively assessing the elements are the significance of the festival and the guarantee of agents' participation in social justification; the ability of agents, as well as cognitional and institutional trust in reliability; expert knowledge, capacity to suggest alternatives and duality of business in professionalism; and effective communication, the guarantee of opening of information and information sharing in transparency. To improve the effectiveness of governance, the system for allowing passive agents to contribute usefully should be strengthened. Mutual communication and sharing of information among agents, as well as between agents and residents, also should be more strongly reinforced.

• Journal of Environmental Impact Assessment
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• v.26 no.6
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• pp.563-573
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• 2017

Coal ash is generated from coal-fired thermal power plants every year. The remaining quantity of coal ash ends up in the landfills except for the recycled portion, and the existing ash pond capacity is limited almost. Currently, the difficulties are faced in building a new ash treatment plant because of the concerns about the environmental impacts of landfills at individual plant facilities. In terms of minimizing the environmental impact, the recycling and effective uses of coal ash are recognized as urgent issues to be challenged. Accordingly, this study examines the obstacles in expanding the recycling of the coal ash in South Korea and proposes solutions based on the case study analysis. The analysis results are as follows: 1) specific recycling guidelines and standards are required to be established in accordance with the contact medium (soil, ground water, surface water and sea water) and the chemical. 2) by providing the recognition environmentally safe in recycling the coal ash, transparency in establishing the planning stages and active communication with the community through promotion and research are essentially needed. 3) practical support system is required to encourage the power plant companies to use the coal ash as beneficial use.