• 한국농촌건축학회논문집
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• 제20권4호
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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.

• 대한지역사회영양학회지
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• 제16권3호
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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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• 제17권4호
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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.

• 자원ㆍ환경경제연구
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• 제15권3호
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• pp.531-553
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• 2006

가정부문 에너지소비의 경우 주로 전력, 난방유, 휘발유, 도시가스, 지역난방 등과 같이 가계가 직접 구입하고 있는 에너지에 대하여 분석이 이루어지고 있다. 총지출 중에서 이러한 직접에너지 구입이 차지하는 비중이 작기 때문에 많은 가계들은 에너지절약에 별 관심을 두지 않고 있다. 2000년의 경우 한국 가정부문은 총지출의 6.2%만을 직접에너지 구입에 사용하였다. 본고는 산업연관표를 사용하여 1990~2000년 기간 동안 한국의 가정부문 직간접 에너지소비를 추정하고, 요인분해방법을 사용하여 가정부문 에너지 총소비 증가요인을 성장효과, 구조효과와 효율효과로 분석하였다. 한국의 가정부문은 2000년에 직접과 간접적으로 각각 1차 에너지의 약 20%와 31%를 소비하였다. 반면에 기존 에너지통계는 자가용 수송에너지를 제외한 2000년 가정부문의 에너지소비를 최종에너지의 15.5%로 추정하고 있다. 간접 에너지를 포함하면 가정부문이 1차 에너지소비의 최대 경제부문이 된다. 가정부문 에너지소비의 60%는 간접 소비다. 에너지 다소비 철강 및 화학 업종을 제외하면 간접에너지 비율이 직접에너지 비율보다 월등히 높다. 따라서 직접 에너지소비보다는 간접과 총 에너지소비가 에너지절약 정책의 주요 대상이 되어야 한다.

• 한국통신학회논문지
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• 제33권4A호
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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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• 제9권1호
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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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• 제14권2호
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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.

• 대한지역사회영양학회지
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• 제16권2호
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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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• 제18권3호
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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.

• 한국농촌건축학회논문집
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• 제19권2호
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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.