• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.126-133
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• 2008

Geotechnical limit state design methods; LRFD of North America is an approach that estimates resistance using design model and then multiplies resistance factor by calculated resistance to reflect the uncertainty of geomaterials and design models; whereas, Eurocode of the Europe employs the partial resistance factor applied directly to each variable in the resistance equation that individual soil properties such as cohesion and angle of internal friction are applied. This discussion paper is a study on characteristic value which has globally been argued through processing of development of Eurocode 7 for geotechnical design even to the present. Estimating the characteristic value of soil properties affects not only determination of design value applied directly to design of geotechnical structures, but also economic feasibility and stability of the structures.

• Nuclear Engineering and Technology
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• v.10 no.1
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• pp.26-36
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• 1978

Numerical computations of radioactivities and decay energies in a spent fuel have been carried out for designing of a hot cell. Optimum wall and window thicknesses that can preserve spent fuel rods for experimental purposes are estimated with burnup rate of 33,000 MWD/T(U) which is nearly maximum from a pressurized water reactor such as the Go-Ri Unit 1. Before putting the spent fuels into a hot cell, it is assumed for thickness estimates of shield materials that they are cooled in a storage tay for several lime intervals. Considered are various types of shield materials through which changing the distances from a source to an observation point is also made.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1994.11a
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• pp.135-140
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• 1994

An improved steam generator model has been developed for the DSNP simulation of normal operational transient behavior of CANDU nuclear power plant. For more realistic prediction of steam generator behavior during transient, tube bundle region is divided into two separate control volumes, subcooled region and saturated region, and the variation of thermal hydraulic properties in the control volume is accounted for more realistic estimates of outlet enthalpy of each control volume. Test results for typical CANDU operational transient case show reasonable transient behavior of steam generator with overall CANDU operation and improved operational characteristics of steam generator with power variation.

• Journal of Hydrogen and New Energy
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• v.32 no.6
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• pp.642-648
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• 2021

In this paper, an experimental study was conducted on the performance of the cooling tower. In order to improve reliability in the cooling tower performance test, the measurement uncertainty of the instrument was estimated. Measurement uncertainty refers to the uncertainty of a measurement, estimates the range in which the expected value of the measurement can be within a certain confidence level, and suggests a range in which the measured representative value is incorrect. Therefore, the measurement result of the performance experiment is not an actual value, but a reasonable estimated value. The measurement uncertainty for the test was calculated and the measured results were presented.

• Environmental and Resource Economics Review
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• v.24 no.4
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• pp.727-745
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• 2015

This paper analyzes the firms' optimization behavior in response to rising demand for non-priced renewable energy in the manufacturing industries by using an input distance function. The annual estimates of the shadow price of renewable energy is derived and the trend of its shadow price over time is analyzed. The degree of substitution of renewable energy for fossil-fuels is examined. The input-based Malmquist productivity index, defined as a composite of the technical efficiency and technical change measures, is measured. The contribution of renewable energy input growth to the Malmquist index is analyzed. Empirical results indicate that the shadow price of renewable energy declined at an average annual rate of 17% over the period 1992-2012. Substitutability between renewable energy and fossil-fuels was limited. On average, a 1% increase in renewable energy would decrease Malmquist index by 0.04% per year.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.301-301
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• 2009

The General program evaluation guide is intended for use by managers of both deployment and R&D programs within the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE), although most of the examples of evaluations pertain to deployment programs(EERE,2006). It could help managers determine what kinds of timely adjustments may be needed in program design or implementation to improve the rate or quality of achievement relative to the committed resources. To consider the adaptation of the method in Korea, we have studied the evaluation case for solar america initiative using cost-benefit evaluation. The President's Solar America Initiative (SAI) was launched in January 2006 as part of the administration's Advanced Energy Initiative. The SAI has a goal of installing 5-10 GW of photovoltaic (PV) systems in the U.S. by 2015 and 70-100 GW of PV systems in the U.S. by 2030. The evaluation report presents estimates of the potential benefits should the SAI PV installation goals be achieved. For this analysis, the areas researched include energy, economic, and environmental benefits. As a result, research suggests that 500 MW of PV may have been enough to avoid lackout. The ability of PV to prevent specific blackouts will depend on very specific information on where the PV installations are installed and their ability to relieve pressure on the high stress points on the grid. While this level of detail is outside the scope of this study, it appears that there will be some potential benefit for blackout prevention should the SAI PV goals be achieved.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.11_12
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• pp.654-662
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• 2005

Mobile portable devices for wireless network solely depend on a limited battery power. Therefore, we need to design for wireless communication protocols with an energy efficiency. TCP-Westwood is one of the most important approaches on TCP performance improvement in wireless environments that estimates the available bandwidth by using the sampling mechanism. The advantage is that data can be transmitted efficiently using the estimation of available bandwidth. However, when the sender with TCP-Westwood is in a wireless environment, it does not consider of the sampling mechanism operation. In this thesis, a new energy saving transport protocol, called E2TP(Energy Efficient Transport Protocol), is proposed to solve problems which occur when the sender with TCP-Westwood is in a wireless environment. Also, when there are packet loss while doing frequent link error in a wireless environment, E2TP provides the instantaneous segment size adjustment for a more efficient data retransmission. The simulation result proves that the proposed E2TP has better performance in energy efficiency and throughput than both TCP and TCP-Westwood.

• Journal of Energy Engineering
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• v.21 no.2
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• pp.179-186
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• 2012

A climate change by increase of greenhouse gas is coming to the front by a large issue, and oxy-combustion demonstration project is coming to the attention to one plans for the reduction of carbon dioxide in power generation sector that used a fossil energy in points of time. This paper estimates benefit of electric generation, benefit of greenhouse gas reduction, benefit of environmental pollutant decreasing and domestic and foreign market value-added benefit caused by oxy-combustion demonstration project. Furthermore, this paper attempts to cost-benefit analysis, using NPV, B/C ratio, IRR techniques for oxy-combustion demonstration project. The results indicate that NPV is 681,620million KRW, B/C ratio 1.69 and IRR 21.4%. Accordingly, oxy-combustion demonstration project ensures economic feasibility that the three indicators have exceeded 0, 1.0 and 5.5%. Moreover, uses of the result is useful for the reduction of carbon dioxide in thermal power generation sector of policy decision.

• Environmental and Resource Economics Review
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• v.21 no.2
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• pp.271-299
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• 2012

The relationship between environment and economic growth has been controversial for a long time. The cores of controversy are endogeneity problem and omitted variable bias. This paper tests EKC (Environmental Kuznets Curves) hypothesis by considering econometric issues and estimates the effects of energy mix on $CO_2$ emissions empirically and tests with time series during 1981~2008. By the results of this analysis, we convince EKC Hypothesis which the relationship between $CO_2$ emissions and economic growth is the inverted U-shaped and the national energy mix contributes significantly to GHG mitigation. We also find that the nuclear energy has the greatest contribution for $CO_2$ mitigation and the renewable energy does not seem to contribute little to the $CO_2$ mitigation because the proportion of renewable energy in Korea is negligible. In terms of final energy consumption, $CO_2$ increases and transportation sector is statistically and significantly associated.

• The KIPS Transactions:PartA
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• v.13A no.2 s.99
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• pp.171-176
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• 2006

In this paper, we develop energy efficient designs for the Fast Fourier Transform (FFT) on FPGAs. Architectures for FFT on FPGAs are designed by investigating and applying techniques for minimizing the energy dissipation. Architectural parmeters such as degrees of vertical and horizontal parallelism are identified and a design choices. We determine design trade-offs using high-level performance estimation to obtain energy-efficient designs. We implemented a set storage types as parameters, on Xilinx Vertex-II FPGA to verify the estimates. Our designs dissipate 57% to 78% less energy than the optimized designs from the Xilinx library. In terms of a comprehensive metric such as EAT (Energy-Area-Time), out designs offer performance improvements of 3-13x over the Xilinx designs.