• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1073-1075
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• 1999

This Paper Presents the process of load management for distribution Pole transformer at KEPCO. The purpose of this process is to establish reasonable peak load forecasting and prevention of Pole transformer damages caused by overload through the investigation of correlation coefficient for recent load characteristics. In this Paper, we newly proposed more reliable correlation coefficient using improved method and verified its reliability in various ways.

• 산업공학
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• 제16권1호
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• pp.16-26
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• 2003

In Korea, cooling power load, which occupies about 20% of peak load in 2000 and fluctuates depending on the popular usage of air conditioning systems, has been recently the focus of the load management. The first work of KEPCO (Korea Electric Power Corporation) to regulate cooling load as low as possible was to estimate its approximate scale and to develop the indirect methods to estimate it from the available time series data for the average hourly loads. However, KEPCO would like to have their methods improved both theoretically and practically. In this paper, we analyze their current indirect methods and detect their faults to design better indirect estimation methods. Under one of the assumptions of "no cooling load in April or May", the linear relationship between basic loads and GDP's, and the normalized seasonal factors of the Winters' multiplicative seasonal model, we provide ten indirect estimation methods in total and suggest the estimated cooling load(1988-1999) based on our various indirect methods.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
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• pp.145-147
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• 2005

This paper presents a methodology for satisfying the thermal comfort of Indoor environment and reducing the summer peak demand power by minimizing the power consumption for an Air-conditioner within a space. KEPCO(Korea Electric Power Corporation) use the fixed duty cycle control method regardless of the indoor thermal environment. This method has disadvantages that energy saying depends on the set-point value of the Air-Conditioner and DLC has no net effects on Air-conditioners if the appliance has a lower operating cycle than the fixed duty cycle. A variable duty cycle estimates the PMV(Predict Mean Vote) at the next step with a predicted temperature and humidity coming from the back propagation neural network model. It is possible to reduce the energy consumption by maintaining the Air-conditioner's OFF state when the PMV lies in the thermal comfort range. The proposed methodology uses the historical real data of Sep. 7th, 2001 from a classroom in seoul to verify the effectiveness of the variable duty cycle method comparing with fixed duty cycle. The result shows that the variable duty cycle reduces the peak demand to 2.6times more than fixed duty cycle and increases the load control ratio by 8% more. Based on the variable duty cycle control algorithm, the effectiveness of DLC is much more improved as compared with the fixed duty cycle.

• 전기전자학회논문지
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• 제18권2호
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• pp.263-271
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• 2014

본 논문에서는 모바일 기기의 배터리 전력관리 IC(Battery Management IC)에서 전압 및 온도를 측정하여 디지털 신호로 바꾸어 주는데 필요한 시그마-델타 모듈레이터를 설계하였다. 제안하는 이산-시간 시그마-델타 모듈레이터는 2차의 단일 비트 구조이고 0.13um CMOS 공정으로 제작되었다. 모듈레이터의 소모전류를 줄이기 위하여 switched-opamp 방식을 적용하여 설계하였다. 제안하는 모듈레이터는 오버 샘플링 비율이 256 일 때 256kHz의 클락 주파수에서 83-dB의 dynamic range와 81.7dB의 peak signal-to-(noise + distortion) ratio(SNDR)를 가진다. 3.3 V의 전원전압에서 0.66 mW의 전력을 소모하며 모듈레이터 코어의 면적은 $0.425mm^2$ 이다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권5호
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• pp.1514-1531
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• 2014

Femtocell provides better coverage and higher spectrum efficiency in areas rarely covered by macrocells. However, serious two-tier interference emerging from randomly deploying femtocells may create dead zones where the service is unavailable for macro-users. In this paper, we present adopting cognitive radio spectrum overlay to avoid intra-tier interference and incorporating spectrum underlay and overlay to coordinate cross-tier interference. It is a novel centralized control strategy appropriate for both uplink and downlink transmission. We introduce the application of proper spectrum sharing strategy plus optimal power allocation to address the issue of OFDM-based femtocells interference-limited downlink transmission, along with, a low-complexity suboptimal solution proposed. Simulation results illustrate the proposed optimal scheme achieves the highest transmission rate on successfully avoiding two-tier interference, and outperforms the traditional spectrum underlay or spectrum overlay, via maximizing the opportunity to transmit. Moreover, the strength of our proposed schemes is further demonstrated by comparison with previous classic power allocation methods, in terms of transmission rate, computational complexity and signal peak-to-average power ratio.

• 한국컴퓨터정보학회논문지
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• 제24권3호
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• pp.29-39
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• 2019

In this study, we introduce a model that satisfies energy efficiency and economical efficiency by introducing and demonstrating cogeneration generators in industrial complexes using various actual data collected at the site. The proposed model is composed of three scenarios, ie, full - time operation, scenario operated according to demand, and a fusion type. In this study, the power generation profit and surplus thermal energy are measured according to the operation of the generator, and the thermal energy is traded according to the demand of the customer to calculate the profit and loss including the heat and evaluate the economic efficiency. As a result of the study, it is relatively profitable to reduce the generation of the generator under the condition that the electricity rate is low and the gas rate is high, while the basic charge is not increased. On the contrary, if the electricity rate is high and the gas rate is low, The more you start up, the more profit you can see. These results show that even a cogeneration power plant with a low economic efficiency due to a low "spark spread" has sufficient economic value if it can sell more than a certain amount of heat energy from a nearby customer and adjust the applied power through peak management.

• 한국운동역학회지
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• 제18권4호
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• pp.125-133
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• 2008

본 연구의 목적은 파워보행 시 하지근의 근활성 정도를 비교 분석하고자 근전도 측정을 통해 파워보행과 일반보행 시 하지근비 평균적분 근전도 및 최대적분 근전도를 측정하였다. 피험자는 근골격계에 이상이 없는 남자 대학생 17명으로 선정하였으며, 실험 간 140 beat/min속도로 보행을 실시하였다. 일반보행 동작과 파워보행 동작의 구간별 근전도치를 비교해 본 결과 일반보행 동작 시 보다, 강하고 힘차게 걷는 파워보행 동작 시에서 측정하고자 하는 하지근의 대부분 근육활동이 전체적으로 높게 나타났다. 특히 보행 동작에서 주동근이 되는 대퇴직근 내측광근, 외측광근의 활동이 일반보행 동작보다 파워보행 동작에서 높게 나타났으며, 발이 지면에서 떨어지기 전 지면을 힘껏 밀 때 사용되어지는 내측비복근, 외측비복근에서, 발뒤꿈치가 지면에 닿을 때 사용되어지는 전경골근에서 일반보행동작보다 파워보행 동작에서 전체적으로 통계적으로 높은 유의한 근육활동이 나타났다. 이는 파워보행 동작이 일반 보행 동작보다 더욱 많은 근육활동을 유발시킴으로 하지근의 근육강화 및 에너지 소비에 직접적으로 도움이 되는 유산소 운동으로써 파워보행을 활용 할 수 있을 것이라 판단되어진다. 따라서 본 연구의 결과 파워보행 동작이 건강유지와 다이어트를 원하는 사람들에게 일반보행 보다 더 높은 효과가 있을 것으로 판단된다.

• 스마트미디어저널
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• 제7권2호
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• pp.71-77
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• 2018

본 논문에서는 신재생에너지 발전과 연계한 에너지저장시스템(ESS)의 최적 운영을 위한 에너지관리시스템(EMS)의 구성요소 설계 시 고려할 기능, 운영 효과 분석과 전력요금 절감 방안을 제안한다. 이를 위해 태양광 발전 시스템에 리튬이온전지 기반의 배터리 시스템과 에너지관리시스템 연계 및 구축방안을 제시하고, 1년 동안 운영 데이터에 대한 분석한 결과를 기술한다. 또한 시스템 운영 효과를 높이기 위한 방안으로 EMS를 이용하여 최대수요 발생시간대의 피크전력을 경부하 시간대 충전전력으로 대체하여 ESS 전용 요금제에 따른 요금편익과 부하 평준화에 기여하는 효과를 제안한다.

• Journal of Preventive Medicine and Public Health
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• 제10권1호
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• pp.94-101
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• 1977

Noise pollution, both in the environment and in the workplace, has been recognized as a major health hazard -one that can impair not only a person's hearing but also his physical and mental well-being. As industrialization progresses, the prevalence rate of occupational diseases is increasing, especially hearing loss, which has the highest prevalence rate among the occupational diseases. The major cause of noise is the construction of various large industries without any regulation of noise sources. Therefor, we must establish an enactment to control mechanical noise sources. as soon as possible. For the purpose of controlling the noise source, we must have exact data about such things as the sound level, the frequency of the peak sound and the revolutions per minute (r.p.m.) of the machine (a measure of the power of its motor). This study was undertaken in order to define the noise characteristics, the power of the machine's motor, the change of the sound level and the peak sound as the r.p.m. increases, and the permissible exposure time. The sample size of this study was 74 machines at 11 plants in 6 industries. The results are as follows; 1. The breakdown of the types of mechanical noise noted was : 63.6% continuous normal sound, 26.9% intermittent sound, 4.7% continuous repeating sound and 4.6% impulsive sound. 2. With respect to the type of industry, the overall sound level was the highest in the mechanical industry, with $103.8{\pm}2.8dB(A)$, and lowest in the textile industry, with $89.2{\pm}1.43dB(A)$. 3. With respect to the type of machine, the highest sound level was 124 dB(A) caused by Gauzing(II), in the mechanical industry, and the lowest was 76 dB(A) caused by Attachment (Jup Chack) (I) in the timber industry. 4. The shortest permissible exposure time to Gauzing(II) in the mechanical industry was less than 15 minutes. 5. Among 74 machines, 68.2% of the peak sound was situated in the high frequency range (52.7% at 2 KHz, 4.1% at 4 KHz and 1.4% at 8 KHz). 41.8% of the peak sound was in the middle frequency range (4.1% at 250Hz, 14.8% at 500Hz and 22.9% at 1KHz). 6. If one machine had two motors or more, the peak sound was shifted to the low frequency range. 7. As the r.p.m. increased, the overall and peak sound levels were increased without any change of the frequency of the peak sound. 8. Whenever the machines had the same kind and the same r.p.m., the overall and peak sounds were changed by the physicochemical characteristics of the raw materials and the management.

• 한국인터넷방송통신학회논문지
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• 제19권2호
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• pp.187-192
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• 2019

수요관리와 정전에 대한 비상전원 기능을 갖춘 하이브리드 전력저장시스템으로 비상발전설비가 필요한 빌딩 및 공장건축 시에 투자비를 최소화하고, 상시 전력비를 절감함으로서 경제성을 확보할 수 있 기술을 개발함으로써 새로운 비즈니스 모델을 제시한다. 평상시에 STS(Static Transfer Switch)를 통해 부하에 계통 전력을 공급하고 PCS는 계통에 병렬로 연계되어 수요관리를 수행한다. EMS는 수요예측을 통한 전력의 효율적 운용을 위해 ESS에 충방전 지령을 PMS(Power Management System)로 하달하고 PMS는 다시 PCS 제어기로 지령을 전달하여 시스템을 운용한다. 정전시에는 STS가 계통으로부터 빠르게 이탈되면서 PCS는 독립 전원이 되어 부하 측에 정전압/정주파수의 전력을 공급할수 있는 구조이다. 따라서 하이브리드 ESS에 대한 실 계통 연계 및 독립 운전 성능 검증을 통한 신뢰성을 확보할수 있고, 저탄소 녹색성장 기술의 효율적 전력망과 연계 운영이 가능하게 함으로써 ESS 연계를 통한 신재생에너지 발전에 의한 불규칙한 전력 품질개선, 피크부하 기여도 제고가 가능하다. 또한 현재 석탄 화력이 담당하고 있는 주파수추종 예비력을 ESS로 대체함에 따라 연료비가 높은 LNG 발전기 가동비용을 절감할 수 있는 기대효과가 있다.