• Journal of the Korean Solar Energy Society
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• v.34 no.6
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• pp.93-102
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• 2014

The aim of this study is to analyze the influence of various factors on energy consumption of apartment buildings. Energy consumption data of the Green Together, integrated building energy management system maintained by the government were used, and end-use and primary energy consumption data of 2012 were analyzed for 181 apartment complexes completed between 2004 and 2011 in Seoul. Energy consumption by use, source and heating type were analyzed. Then, energy consumption trends were analyzed and suggested according to energy efficiency ratings, number of households, areas for exclusive use, number of floors, core types, building types, orientations and completion years.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.7
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• pp.43-52
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• 2018

In this study, annual site and primary energy use intensities (EUIs) and CO2 emission intensities (CEIs) per area by end use were estimated based on the measurement data from June 2016 to May 2017 of 50 sample apartment units in Seoul. In addition, estimated site EUIs by end use were compared to the U.S. Residential Energy Consumption Survey (RECS) 2009 data. Site EUIs by end use were found to be in the order of heating > electric appliance > domestic hot water > cooking > lighting > cooling > air movement. In the case of primary EUIs and CEIs by end use, electric appliance was found to be the largest. As results of comparison with the RECS 2009 data, it was found that site EUIs were very similar for heating, domestic hot water and electric appliance, etc., but slightly different for cooling. The number of sample apartment units will continue to increase until 2020 (total number of samples 200) and intensities data by end use will be continuously updated through continuous collection of measurement data.

• Journal of Communications and Networks
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• v.16 no.5
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• pp.485-492
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• 2014

Spectrum sensing for cognitive-radio applications may use a matched-filter detector (in the presence of full knowledge of the signal that may be transmitted by the primary user) or an energy detector (when that knowledge is missing). An intermediate situation occurs when the primary signal is imperfectly known, in which case we advocate the use of a linear-quadratic detector. We show how this detector can be designed by maximizing its deflection, and, using moment-bound theory, we examine its robustness to the variations of the actual probability distribution of the inaccurately known primary signal.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.12
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• pp.4600-4616
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• 2021

In cognitive radio networks where unlicensed secondary users opportunistically access to licensed spectrum unused by licensed primary users, spectrum sensing is one of the key issues in order to effectively use the frequency resource. For enhancing the sensing performance in energy detection-based spectrum sensing, spatial diversity based on multiple antennas is utilized. However, the sensing performance can be degraded when antennas are spatially correlated, resulting in inducing the harmful interference to primary users. To overcome this problem, in this paper, an advanced energy detector is proposed. In the proposed sensing method, a weight matrix based on the eigenvalues of the spatial channels without any prior information on the primary signals is defined and utilized. In numerical simulations, it is shown that the proposed detector outperforms the conventional detector with regard to false-alarm and detection probabilities when antenna are spatially correlated.

• KIEAE Journal
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• v.14 no.4
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• pp.47-52
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• 2014

The problem of energy consumption is more serious in university buildings than primary, middle and high school buildings. Because university buildings have generally heating and cooling systems, and various incidental facilities. In university, the library is one of the building that many people use and the most energy is spent. So, investigation on energy saving is very important and urgent. This study aims finally to present the guideline for low-energy design of University library by aiding a designer to select best solution in the side of energy-saving. In this paper, composition of space, utilization schedule and performance of construction materials are grasped, some primary factors that effect to energy saving are analyzed by energy simulation. The result of this study is as follows; First, the subject library has more cooling load than heating load because of cooling load generated during middle season. Second, green roofs is the most effective to heating load saving, but not to cooling energy. Third, outdoor air cooling is the most effective to cooling energy saving among the investigated strategies included in this study.

• Hwankyungkyoyuk
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• v.10 no.2
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• pp.325-338
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• 1997

Review of the global change in various energy usages and resulting environmental impacts were made in terms of population increase, economic development and energy consumption. Greater use of fossil fuels in past couple of centuries give rise to acid rain and gradual climate changes mainly due to Green House inducing gases emissions from fossil fuel combustion. In view of the forthcoming Kyoto conference in December, various alternative options were assessed. To cope with rapidly developing robust Korean economy, the alternative energy options for the sustainable development in 21st Century would be the wider use of Nuclear Energy in parallel with constrained use of fossil fuel and renewable energy development. However there are many hurdles to overcome. One of the most important element is to improve public acceptability of those alternatives. Since public acceptance depend heavily upon individual perception on specific energy technology applications, the basic energy technologies education from primary up to high school education and the related curriculum organization is important. The suggested improvement in education for Nuclear Energy Application was made on the basis of advanced industrial countries with substantial Nuclear Energy Application programs.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.8
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• pp.19-27
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• 2018

In this study, annual site and primary energy use intensities (EUIs) and $CO_2$ emission intensities (CEIs) per area by end use were estimated based on the measurement data from June 2016 to May 2017 of 19 sample office buildings in Seoul. In addition, the estimated site EUIs by end use were compared to the U.S. Commercial Buildings Energy Consumption Survey (CBECS) 2012 data. Average site EUIs by end use were found to be in the order of electric appliance (typical floors) > heating > cooling > lighting > air movement > domestic hot water > vertical transportation > city water supply. In the case of primary EUIs and CEIs by end use, electric appliance was found to be the largest. As results of comparison with the CBECS 2012 data, it was found that the site EUIs were similar for heating, cooling, domestic hot water, and electric appliance, etc., but slightly different for lighting and air movement. The number of sample office buildings will continue to increase until 2020 (total number of samples 85) and intensities data by end use will be continuously updated through continuous collection of measurement data.

• Journal of Electrical Engineering and Technology
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• v.11 no.3
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• pp.707-714
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• 2016

We present a piezoelectric energy harvester with stopper-engaged dynamic magnifier which is capable of significantly increasing the operating bandwidth and the energy (power) harvested from a broad range of low frequency vibrations (<30 Hz). It uses a mass-loaded polymer beam (primary spring-mass system) that works as a dynamic magnifier for another mass-loaded piezoelectric beam (secondary spring-mass system) clamped on primary mass, constituting a two-degree-of-freedom (2-DOF) system. Use of polymer (polycarbonate) as the primary beam allows the harvester not only to respond to low frequency vibrations but also generates high impulsive force while the primary mass engages the base stopper. Upon excitation, the dynamic magnifier causes mechanical impact on the base stopper and transfers a secondary shock (in the form of impulsive force) to the energy harvesting element resulting in an increased strain in it and triggers nonlinear frequency up-conversion mechanism. Therefore, it generates almost four times larger average power and exhibits over 250% wider half-power bandwidth than those of its conventional 2-DOF counterpart (without stopper). Experimental results indicate that the proposed device is highly applicable to vibration energy harvesting in automobiles.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.401-407
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• 2022

Central heating, ventilation and air conditioning (HVAC) is one of the largest consumers of energy in the residential sector. This project explores the use of multiple HVAC units and/or Zoning in a single residence to reduce energy loads. The energy consumption data of a detached single-family home using two HVAC units, one primary for the main house and a secondary HVAC for a casita, was collected for the same month for two consecutive years, along with details related to the outdoor temperature and the square footage being air-conditioned by each HVAC. A regression algorithm was trained using the above details to find the relation between the parameters. Next, based on the occupancy and usage patterns, the HVAC was redesigned assuming more area under the secondary HVAC unit. The trained algorithm was then used to make energy usage predictions for the revised primary HVAC area, with the assumption that the secondary HVAC unit was turned off. The results were compared with existing energy usage data. It was determined that there were significant energy savings in the second scenario. It is expected that this study and its findings will help future research projects explore more ideas as alternatives to central HVAC, in improving the economic viability of existing options, and in developing a savings calculation tool that will help consumers make informed decisions on their best alternatives to central HVAC.

• Journal of the Korean Solar Energy Society
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• v.39 no.5
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• pp.29-40
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• 2019

In response to the rapid climate change, in order to save energy in the field of buildings, the country is planning not only zero energy buildings but also zero energy cities. In the Urban Development Project, the Energy Use Plan Report is prepared and submitted by predicting the amount of energy demand at the planning stage. However, due to the activation of zero-energy buildings and the increase in the supply of new and renewable energy facilities, the energy consumption behavior of buildings in the city is changing from the previous ones. In this study, to estimate urban energy demand of Zero Energy City, building energy demand forecasts based on "Passive plans for use of energy based primary energy consumption", "Actual building energy usage data from Korea Appraisal Board" and "data from Certification of Building Energy Efficiency Rating" as well as demand forecast according to existing "Consultation about Energy Use Plan Code" were calculated and then applied to Multifunctional Administrative City 5-1 zone to compare urban total energy demand forecasts.