• 한국인공지능학회지
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• 제11권2호
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• pp.1-6
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• 2023

This paper presents a comprehensive scheme for assessing the importance of multiple microgrids (MGs) network that includes distributed energy resources (DERs), renewable energy systems (RESs), and energy storage system (ESS) facilities. Due to the uncertainty of severe weather, large-scale cascading failures are inevitable in energy networks. making the assessment of the structural vulnerability of the energy network an attractive research theme. This attention has led to the identification of the importance of measuring energy nodes. In multiple MG networks, the energy nodes are regarded as one MG. This paper presents a modified PageRank algorithm to assess the importance of MGs that include multiple DERs and ESS. With the importance rank order list of the multiple MG networks, the core MG (or node) of power production and consumption can be identified. Identifying such an MG is useful in preventing cascading failures by distributing the concentration on the core node, while increasing the effective link connection of the energy flow and energy trade. This scheme can be applied to identify the most profitable MG in the energy trade market so that the deployment operation of the MG connection can be decided to increase the effectiveness of energy usages. By identifying the important MG nodes in the network, it can help improve the resilience and robustness of the power grid system against large-scale cascading failures and other unexpected events. The proposed algorithm can point out which MG node is important in the MGs power grid network and thus, it could prevent the cascading failure by distributing the important MG node's role to other MG nodes.

• Journal of Information Processing Systems
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• 제14권4호
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• pp.948-960
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• 2018

Many mobile sensing frameworks have been developed to help researcher doing their mobile sensing research. However, energy consumption is still an issue in the mobile sensing research, and the existing frameworks do not provide enough solution for solving the issue. We have surveyed several mobile sensing frameworks and carefully chose one framework to improve. We have designed an adaptive sampling module for a mobile sensing framework to help solve the energy consumption issue. However, in this study, we limit our design to an adaptive sampling module for the location and motion sensors. In our adaptive sampling module, we utilize the significant motion sensor to help the adaptive sampling. We experimented with two sampling strategies that utilized the significant motion sensor to achieve low-power consumption during the continuous sampling. The first strategy is to utilize the sensor naively only while the second one is to add the duty cycle to the naive approach. We show that both strategies achieve low energy consumption, but the one that is combined with the duty cycle achieves better result.

• 한국산업융합학회 논문집
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• 제26권4_2호
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• pp.657-668
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• 2023

It's important to note that air compressors in the industrial sector are major energy consumers, accounting for a significant portion of total energy costs in manufacturing plants, ranging from 12% to 40%. To address this issue, researchers have compared forecasting models that can predict the power consumption of air compressors. The forecasting models were designed to incorporate variables such as flow rate, pressure, temperature, humidity, and dew point, utilizing statistical methods, machine learning, and deep learning techniques. The model performance was compared using measures such as RMSE, MAE and SMAPE. Out of the 21 models tested, the Elastic Net, a statistical method, proved to be the most effective in power comsumption forecasting.

• 한국ITS학회 논문지
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• 제11권3호
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• pp.31-39
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• 2012

이 논문에서는 이동 애드혹 네트워크 환경에서 네트워크 생존시간을 최대화하기 위한 에너지 인지 기반 라우팅 프로토콜을 제안한다. 제안 라우팅 프로토콜은 소스 라우팅 방식을 기반으로 하며, 이동 노드의 송수신 전력 소모량과 배터리 잔량을 소스 노드와 목적지 노드 종단간 고려하여 생존시간이 가장 긴 경로를 선택한다. 이를 위한 새로운 라우팅 비용을 제안하며, 경로 탐색시 발생하는 제어 패킷 오버헤드를 최소화하는 라우팅 프로토콜을 설계한다. 시뮬레이션 결과 제안방식은 전송 홉 수, 전송률, 에너지 소비량 측면에서 기존 방식과 비슷한 수준의 성능을 보이면서, 생존시간 측면에서는 기존 방식 대비 약 20%의 성능향상을 보여준다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1261-1266
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• 2008

Experimental study was performed to understand the operations of a showcase working in a discount store. Temperatures of evaporation, condenser were measured and also electric power consumption of compressor were measured. The purpose of this study is to application use of cold-heat storage systems operated the showcase. At the condition using ice storage system, the ice making process was operated during midnight being not needed the cooling of the showcase through the continuous running of the condenser unit. And then, the refrigerant was sub-cooled using stored cold-heat after being discharged from the air cooling condenser during the day time. The cooling performance was increased owing to the sub-cooling of refrigerant during day time, hence the running time of the compressor was effectively decreased. In other words, this study showed that power consumption during daytime can be transferred to the midnight for making use of the refrigerant sub-cooling. So the operating characteristics of the showcase system under various working conditions were analyzed and discussed.

• 한국산업정보학회논문지
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• 제17권4호
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• pp.17-23
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• 2012

초저전력 설계나 에너지 수확 활용은 동적 전력과 정적 전력 사이의 균형을 이루는 점에 근접하는 문턱전압이하의 매우 낮은 전압에서 작동하는 디지털 시스템을 요구한다. 이런 동작 모드에서 일반적인 논리회로의 지연 변화는 매우 크게 된다. 따라서, 본 논문에서 MOSFET 나노 공정기술에서 전력소비를 줄이면서 여러 가지 공정 변이의 영향을 받지 않는 비동기 방식의 NCL (Null conventional logic)을 사용한 저전력 논리회로 설계 방법을 제안하고자 한다. 제안된 NCL 회로는 45nm의 공정기술에서 0.4V의 공급전압을 사용하였고, 각 NCL회로는 속도와 전력에 의해서 일반적인 동기식 회로와 비교되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.1293-1295
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• 2001

Recently, according to developing industry and life style, power consumption have been increased year after year. Currently these much power demand from power consumer weakening the allowable power reverse margin in summer. As on of the remedies about this problem, the small scale grid-connected photovoltaic system is considered for auxiliary power source. Generally, grid-connected inverter have a isolation transformer for electrical isolation from utility. This paper proposed transformerless system topology an inquiry validity simulation.

• 에너지공학
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• 제27권3호
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• pp.57-62
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• 2018

The development of coal-fired power plants to ensure energy security and electricity consumption is a matter for the Vietnam economy. However, the huge amount of ash discharged is a major environmental challenge. It is estimated that by the end of 2017, the amount of ash in the country is about 40 million tons and annually emitted over 16.4 million tons. While the quantity of coal-fired power plant is rising, the ash content will increase year by year if the ash doesn't treat well. The ash will be increased from 61 million tons in 2018 to 109 million tons in 2020, 248 million tons in 2025 and 422 million tons in 2030. The difficulties of coal-fired power plants are the problem of ash handling, some plants are at risk of closure because there are not enough dump capacity to storage. Therefore, Vietnam is in need of urgent measures to treat a large amount of waste from coal-fired power plants. The specific objectives of this study were as follows: (1) provide an overview of coal ash situation produced by coal-fired power plants in Vietnam; (2) study about regulations related to coal ash treatment; (3) comprehend the literature review of the cement sector status.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술회의 초록집
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• pp.7-7
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• 2010

Energy harvesting from the environment has been of great interest as a standalone power source of wireless sensor nodes for Ubiquitous Sensor Networks(USN). In particular, the piezoelectric energy harvesting from ambient vibration sources has intensively researched because it has a relatively high power density comparing with other energy scavenging methods. Through recent advances in low power consumption RF transmitters and sensors, it is possible to adopt a micro-power energy harvesting system realized by MEMS technology for the system-on-chip. However, the MEMS energy harvesting system has some drawbacks such as a high natural frequency over 300 Hz and a small power generation due to a small dimension. To overcome these limitations, we devised a novel power generator with a spiral spring structure as shown in the figure. The natural frequency of a cantilever could be decreased to the usable frequency region (under 300 Hz) because the natural frequency depends on the length of a cantilever. In this study, the natural frequency of the energy harvester was a lower than a normal cantilever structure and sufficiently controllable in 50 - 200 Hz frequency region as adjusting weight of a proof mass. Moreover, the MEMS energy harvester had a high energy conversion efficiency using a shear mode ($d_{15}$) is much larger than a 33 mode ($d_{33}$) and the energy conversion efficiency is proportional to the piezoelectric constant (d). We expect the spiral type MEMS power generator would be a good candidate for a standalone power generator for USN.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권12호
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• pp.5744-5764
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• 2018

In Wireless Sensor Networks (WSNs) for Internet of Things (IoT) environment, fault tolerance is a most fundamental issue due to strict energy constraint of sensor node. In this paper, a robust energy saving data dissemination protocol for IoT-WSNs is proposed. Minimized energy consumption and dissemination delay time based on signal strength play an important role in our scheme. The representative dissemination protocol SPIN (Sensor Protocols for Information via Negotiation) overcomes overlapped data problem of the classical Flooding scheme. However, SPIN never considers distance between nodes, thus the issue of dissemination energy consumption is becoming more important problem. In order to minimize the energy consumption, the shortest path between sensors should be considered to disseminate the data through the entire IoT-WSNs. SPMS (Shortest Path Mined SPIN) scheme creates routing tables using Bellman Ford method and forwards data through a multi-hop manner to optimize power consumption and delay time. Due to these properties, it is very hard to avoid heavy traffic when routing information is updated. Additionally, a node failure of SPMS would be caused by frequently using some sensors on the shortest path, thus network lifetime might be shortened quickly. In contrast, our scheme is resilient to these failures because it employs energy aware concept. The dissemination delay time of the proposed protocol without a routing table is similar to that of shortest path-based SPMS. In addition, our protocol does not require routing table, which needs a lot of control packets, thus it prevents excessive control message generation. Finally, the proposed scheme outperforms previous schemes in terms of data transmission success ratio, therefore our protocol could be appropriate for IoT-WSNs environment.