• Journal of the Korean Institute of Rural Architecture
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• v.20 no.4
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• pp.1-8
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• 2018

In this study, we survey the 2 buildings at the Central 1 and 8 buildings at the Central 2, which are divided by each climate region in the rural regions. Major heat loss factors are 47% loss of the outer shell including outer wall, roof, and bottom, 30% loss through window, and 23% loss through crevice wind. We analyze the energy simulation of ECO2 program to construct a zero energy building regarding village hall located in Jung Juk 4-le at Centeral 2. We simulate the primary energy requirement regarding village hall and the simulated results show the $265.3kWh/m^2{\cdot}a$ and it may estimate '2' energy efficiency grade. The energy requirement regarding village hall is the $183.2kWh/m^2{\cdot}a$ when the passive technology are applied in village hall. We research total amount of energy requirement in village hall when the passive and active technologies such as solar cell with 3kW and solar thermal with $20m^2$, geothermal power with 17.5kW. The simulated results show the improved energy efficiency certification grade with $1^{{+}{+}{+}}$ due to the reduced primary energy requirement with 73% when passive technology including 3kW of solar panel is applied and the energy independence rate is 54%, which is estimated to be 4th grade of zero energy buildings. The order of energy consumption are solar panel, solar thermal, and geothermal power under applied passive technology in the building. In order to expand the zero energy building, it is necessary to introduce the zero energy evaluation system in the rural region.

• Korean Journal of Community Nutrition
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• v.16 no.3
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• pp.307-314
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• 2011

The purpose of this study is finding the easy way of 4 categories activity level confirmation for estimated energy requirement calculation. Total of 386, 5th and 6th grade primary school students participated. The time spent on 7 kinds of activity were collected for 1 day by the internet program developed. Judged by the activity coefficient, sedentary were 6.7% and 5.1%, low active 33.2% and 40.4%, active 43.8%, and45.5%, and very active 16.3% and 9.0% for boy and girl, respectively. The highest and significant correlation coefficient between activity coefficient and time spent on activities shown were 0.339 in commute activity for boys, and 0.466 in leisure for girls. The sensitivity of the sedentary conformation by commute hour for boys was 0.79, and that of very active was 0.56. The sensitivity of the sedentary conformation by leisure hour for girls was 0.67, and that of very active was 0.63. The sensitivity of low active and active by 7 different types of activity was quite low, 0.04~0.37. The exact agreement of activity level conformed by easy way developed was 30.8% and 33.7%, for boys and girls, respectively. More accurate way to identify 4 categories activity level needs to be developed, especially sensitive to conformation of low active and active levels.

• KIEAE Journal
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• v.17 no.4
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• pp.67-74
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• 2017

Purpose: As the recent climate environment changes so rapidly, environmental problems such as hot weather and fine dust have occurred, and interest in environmental policies and technology development is increasing in countries around the world. Similarly in the Architecture, researches to reduce greenhouse gas emissions and to reduce energy application are actively conducted. Looking at previous studies, it is analyzed that the electric VRF is more energy efficient than the gas engine VRF. However, energy costs have changed due to recent price hikes and discounts on gas charges due to high electricity consumption in summer. Method: In this study, the actual building of Gas Engine VRF system was modeled using SketchUp program, and EnergyPlus was used to simulate actual building. Also, Electric VRF system was simulated, and compared with Gas Engine VRF system. Result: The total secondary energy requirement of Electric VRF system was 19.6% less than that of the Gas Engine VRF system, But when analyzing with primary energy requirement, EHP used 15.8% more energy. CO2 emissions were also estimated to be 16.9% more EHP. Energy costs were 14.8% more in Electric VRF systems, because their electricity charges are 0.6 to 160% more expensive than gas charges.

• Environmental and Resource Economics Review
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• v.15 no.3
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• pp.531-553
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• 2006

As energy conservation can be realized through changes in the composition of goods and services consumed, there is a need to assess indirect and total household energy requirements. The Korean household sector was responsible for about 55% of the country's primary energy requirement in the period from 1990 to 2000. And more than 60% of household energy requirement was indirect. Thus, indirect and total rather than direct household energy requirements should be the target of energy conservation policies. Increases in household consumption expenditure were responsible for a relatively high growth of energy consumption. Switching to consumption of less energy intensive products and decrease in energy intensities of products contributed substantially to reduce the increase in total household energy requirement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.458-466
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• 2008

Spectrum sensing is the key challenge in implementing cognitive radio system, which enables unlicensed users to identify "white holes" in the spectrum allocated to primary users and utilize them efficiently. Recent studies have proposed three major sensing methods for WRAN systems, including matched filter, energy and feature detector. However, there are some drawbacks along with them. In this paper, we propose an enhanced energy detector that extends the ability of conventional one, which can differentiate the primary users from each other as well as the noise with different maximum-to-mean power ratio. Furthermore, a novel structure of cognitive radio detector employing the proposed algorithm is also analyzed to implement spectrum sensing. The simulation result shows that our proposed scheme performs well in the individual sensing environment and can satisfy the requirement with high detection probability.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.71-79
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• 2014

This paper discusses a method for the determination of frequency control reserve requirement with consideration of the interaction between ex-ante planning and real-time balancing. In proposed method, we consider the fact that the delivered energy for tertiary control reserve is determined based on required capacity for secondary control reserve and the expected amount of load errors. Uncertain load errors are derived by Brownian motion, an optimization method is suggested using a stochastic programming. In a short, we propose an interactive dependent method for determining secondary control reserve requirement based on the principle that it satisfies to minimize the total cost. As a result, this paper provides will analyze for an example model to demonstrate the capabilities of the method.

• Journal of Communications and Networks
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• v.14 no.2
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• pp.162-168
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• 2012

This paper considers the scenario in which a set of nodes share a common channel. Some nodes have a rechargeable battery and the others are plugged to a reliable power supply and, thus, have no energy limitations. We consider two source-destination pairs and apply the concept of cognitive radio communication in sharing the common channel. Specifically, we give high-priority to the energy-constrained source-destination pair, i.e., primary pair, and low-priority to the pair which is free from such constraint, i.e., secondary pair. In contrast to the traditional notion of cognitive radio, in which the secondary transmitter is required to relinquish the channel as soon as the primary is detected, the secondary transmitter not only utilizes the idle slots of primary pair but also transmits along with the primary transmitter with probability p. This is possible because we consider the general multi-packet reception model. Given the requirement on the primary pair's throughput, the probability p is chosen to maximize the secondary pair's throughput. To this end, we obtain two-dimensional maximum stable throughput region which describes the theoretical limit on rates that we can push into the network while maintaining the queues in the network to be stable. The result is obtained for both cases in which the capacity of the battery at the primary node is infinite and also finite.

• Korean Journal of Community Nutrition
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• v.16 no.2
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• pp.195-205
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• 2011

This study was conducted to investigate the time spent, activity coefficient and energy expenditure on 7 different types of activity. Total of 386 5th and 6th grade primary school boys and girls in Seoul participated in this study. The participants spent 8 hrs for rest, 4 hrs for out of school study, 3 hrs for leisure, 1 hr 45 mins. for hygiene, 1 hr for commute, and 15 mins. for house choir activity in the day of 6 class hours. The average activity coefficient of 1 day for boys and girls were 1.69 and 1.64, respectively. The TEEs were 2,382 kcal and 2,050 kcal for boys and girls, respectively. The energy cost for study related activity (in school and study activities) was 40% of the TEE, and for rest 20%, for commute 9%, and for hygiene 10% of the TEE. The energy cost for house choir was only about 2% of TEE. The 91.2% participant's EER was higher than the EER shown in the table of 2010 DRI for Koreans. When the participant's EER was compared with the energy allowance calculated by the method in 2000 RDA for Korean, 81.6% was in the range of ${\pm}5%$, and the correlation coefficients between the 2 values were 0.981 for boys and 0.978 for girls, which means high agreements.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.3
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• pp.579-587
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• 2017

Spaceborne cryocoolers produce undesirable micro-vibration disturbances during their on-orbit operation, which are a primary source of image-quality degradation for high-resolution observation satellites. Therefore, to comply with the strict mission requirement of high-quality image acquisition, micro-vibration disturbances induced by cooler operation have always been subjected to an isolation objective. However, in this study, we focused on the applicability of energy harvesting technology to generate electrical energy from micro-vibration energy of the cooler and investigated the feasibility of utilizing harvested energy as a power source to operate low-power-consumption devices such as micro-electromechanical system (MEMS) devices. A tuned mass damper (TMD)-type electromagnetic energy harvester combined with a conventional passive vibration isolator was proposed to achieve this objective. The system performs the dual functions of electrical energy generation and micro-vibration isolation. The effectiveness of the strategy was evaluated through numerical simulations.

• Journal of the Korean Institute of Rural Architecture
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• v.19 no.2
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• pp.9-16
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• 2017

The study analyzed the heat losses and the building energy efficiency grade by the energy simulation using the ENERGY# and ECO2 programs for the three types of Standard design of rural houses. It was calculated the energy efficiency rating by the ECO2 program for the rural housing standard design, and the energy demand and the energy consumption by each factor were compared and analyzed. And it analyzed energy consumption by element of each house by ENERGY # program. As a result, first in the evaluation of the energy efficiency grade of buildings by the ECO2 program, the rating for primary energy requirement for the housing newly built by the standard design of rural house is expected to range from 2 to 4 with 189.3 to $238.7kWh/m^2.a$. Second, the energy loss of each part of standard design of rural housing occurs in the order of ventilation 39%, window 33%, outer wall 14%, roof 9%, bottom 5%, and energy loss through ventilation and window occurs more than 70%. Third, the most beneficial effects on the energy efficiency grade is obtained the lowest grade of all three types by 2 when the lowering of the window and door heat transmission rate and the lowering of the light density, and the heat exchange ventilation device is not installed. Fourth, in the standard design of rural housing, the energy demand is occupied by heating > hot water > lighting order, and the order of the weight is changed in order of heating > lighting > ventilation > hot water. Fifth, building energy efficiency assessment system needs to establish policy for fixing rural housing energy as a practical device to ensure energy performance and quality.