• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권4호
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• pp.1437-1459
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• 2020

Wireless Sensor Networks (WSN) is a distributed Sensor network whose terminals are sensors that can sense and check the environment. Sensors are typically battery-powered and deployed in where the batteries are difficult to replace. Therefore, maximize the consumption of node energy and extend the network's life cycle are the problems that must to face. Low-energy adaptive clustering hierarchy (LEACH) protocol is an adaptive clustering topology algorithm, which can make the nodes in the network consume energy in a relatively balanced way and prolong the network lifetime. In this paper, the novel multi-objective LEACH protocol is proposed, in order to solve the proposed protocol, we design a multi-objective coupling algorithm based on bat algorithm (BA), glowworm swarm optimization algorithm (GSO) and bacterial foraging optimization algorithm (BFO). The advantages of BA, GSO and BFO are inherited in the multi-objective coupling algorithm (MBGF), which is tested on ZDT and SCH benchmarks, the results are shown the MBGF is superior. Then the multi-objective coupling algorithm is applied in the multi-objective LEACH protocol, experimental results show that the multi-objective LEACH protocol can greatly reduce the energy consumption of the node and prolong the network life cycle.

• 한국전자통신학회논문지
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• 제7권5호
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• pp.983-989
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• 2012

IEEE 802.3az LPI 메커니즘은 전송할 데이터가 없을 경우 취침 모드로 천이하여 다수의 컴포넌트들을 저전력 상태를 유지하게 함으로써 에너지 효율성을 향상시킨다. LPI는 소량의 데이터가 주기적으로 전송되는 상황에서는 잦은 전송 모드 변환에 따른 오버헤드 때문에 에너지 효율이 크게 개선되지 못하는 문제점이 있다. 본 논문에서는 전송계층 트래픽 특성 및 네트워크 상태에 따라 LPI 모드 상태 천이를 적응적으로 수행하는 개선된 LPI 메커니즘을 제안한다. 시뮬레이션 방법에 의한 성능 분석을 통해 제안한 메커니즘이 다양한 트래픽 부하에 대해서 기존 방법보다 에너지 효율성을 향상시키는 것으로 나타났다.

• Journal of Electrical Engineering and Technology
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• 제8권5호
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• pp.975-983
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• 2013

This study proposes a low order dynamic model of a building system in order to predict thermal behavior within a building and its energy consumption. The building system includes a thermally well-insulated room and an electric heater. It is modeled by a second order lumped RC thermal network based on the thermal-electrical analogy. In order to identify unknown parameters of the model, an experimental procedure is firstly detailed. Then, the different linear parametric models (ARMA, ARX, ARMAX, BJ, and OE models) are recalled. The parameters of the parametric models are obtained by the least square approach. The obtained parameters are interpreted to the parameters of the physically based model in accordance with their relationship. Afterwards, the obtained models are implemented in Matlab/Simulink(R) and are evaluated by the mean of the sum of absolute error (MAE) and the mean of the sum of square error (MSE) with the variable of indoor temperature of the room. Quantities of electrical energy and converted thermal energy are also compared. This study will permit a further study on Model Predictive Control adapting to the proposed model in order to reduce energy consumption of the building.

• Journal of Advanced Marine Engineering and Technology
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• 제8권2호
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• pp.25-38
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• 1984

Since the energy shock in 1973, there have been wide studies for the developments of the alternative energy source, the rationalization of the energy utilization and the energy economy because of the recognition of the limitation of energy source all over the world. This study is experimentally examined in and compared with the engine performance of output, torque and fuel consumption rate, and the exhaust emissions with the change of engine rmp in the cases of using water-gashol blends, gashol and gasoline as a fuel in a conventional 4 cycle 4 cylinder gasoline engine. In the case of using water-gashol blends, it is installed by the exhaust manifold pipe into the intake manifold, and water is injected from nozzle fitted up the air horn of the carburetor. The results are obtained as follows; 1. In the case of an addition with water, the engine output and the torque are little difference with the case of gasoline. 2. The fuel consumption rate is decreased as compared with the case of gasoline. Especially, the decrease in quantity is remarkable at the low rpm. 3. The exhaust emissions are remarkably decreased as compared with the case of gasoline. Especially, decreases of CO and HC in quantity are remarkable at the low rpm, and a decrease of No/sub x/ in quantity is remarkable at the high rpm. 4. There is a moderate condition of operation because the producing factors of NO/sub x/ and CO, HC are contrary to each other.

• 국제초고층학회논문집
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• 제6권2호
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• pp.113-129
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• 2017

This paper presents the initial findings of a ground-breaking two-year CTBUH-funded research project investigating the real environmental and social sustainability of people's lifestyles in a number of high-rise residential towers in downtown Chicago, and a comparable number of low rise homes in suburban Oak Park, Chicago - based on actual energy bills and other real data. The study is ground-breaking because, to date, similar studies have been mostly based on very large data sets of generalized data regarding whole-city energy consumption, or large-scale transport patterns, which often misses important nuances. This study has thus prioritized quality of real data (based on around 250 households in both high rise and low rise case studies), over quantity. In both urban and suburban cases, the following factors have been assessed: (i) home operational energy use, (ii) embodied energy of the dwelling, (iii) home water consumption, (iv) mobility and transport movements, (v) urban/suburban Infrastructure, and (vi) quality of life. The full results of this seminal study will be published in the form of a CTBUH Research Report publication in 2017. Presented below is an overview of the initial (and, currently, unverified) findings of the research, together with the limitations of the study that should be taken into account, as well as future plans for developing this important pilot study.

• 한국환경과학회지
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• 제25권10호
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• pp.1381-1387
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• 2016

This study aims to establish baseline data for sustainable monitoring by applying the green city index (GCI), which is set up to evaluate the city level, to the city of Gangneung-si, which was designated as a pilot city for the Low-carbon Green Growth City project by the Ministry of Land, Infrastructure, and Transportation. The GCI was applied in the framework of European systems, while considering the social and economic status of Korea. Indicators from 7 areas-$CO_2$, energy, building, transportation, water, waste, and quality of atmosphere were analyzed, except for qualitative indicators. Results indicate that total $CO_2$ emissions were 30.8 tons per capita, or 2.2 tons per one million units of real GDP. The total final energy consumption was 0.231 TOE/capita, or 0.317 TOE per one million units of real GDP. The percentage of total energy derived from renewable resources was 0.41% and energy consumption by the building was $433.5Mwh/1,000m^2$. The total percentage of the working population travelling to work daily by public transportation (limited to bus) was 19%. Further, the total annual water consumption was $99m^3/capita$, and the water lost in the water distribution system was $0.057m^3/capita/day$. The total annual waste collected was 0.0077 ton per capita, The annual mean emission were 0.014 ppm/day for $NO_2$, 0.005 ppm/day for $SO_2$, and 0.019 ppm/day for $O_3$. The annual mean for PM10 emissions was $39{\mu}g/m^3/day$.

• 한국정보통신학회논문지
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• 제24권2호
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• pp.285-289
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• 2020

무선 네트워크의 계층적 구성은 다양한 네트워크 환경을 지원하기 위해 제공된다. 기지국에서는 두 가지 시스템 상태가 기본적으로 고려될 수 있으며, 이에 대해 액티브와 슬립 모드 사이에서 상태 전이가 발생할 수 있다. 그러므로 에너지 사용을 줄이기 위하여 저전력의 시스템 운영 관리가 기지국 시스템에 고려되어야 한다. 따라서 본 논문에서는 시스템 관리를 다루기 위해 Discontinuous Reception (DRX) 분석 모델을 고려한다. DRX 모델을 통하여 기지국 시스템의 운영에 대한 분석 방안을 제시하며 에너지 소비를 위한 저전력 강도를 살펴본다. 또한 시스템 상태에서 기지국의 저전력 소모에 대한 성능을 분석하기 위해 무선 자원 요구와 서비스 호 도착의 운영이 고려되며, 이를 위하여 유한 마르코프 시스템 모델을 사용하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권8호
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• pp.2140-2156
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• 2023

The Wireless Sensor Network (WSN), is constructed out of teeny-tiny sensor nodes that are very low-cost, have a low impact on the environment in terms of the amount of power they consume, and are able to successfully transmit data to the base station. The primary challenges that are presented by WSN are those that are posed by the distance between nodes, the amount of energy that is consumed, and the delay in time. The sensor node's source of power supply is a battery, and this particular battery is not capable of being recharged. In this scenario, the amount of energy that is consumed rises in direct proportion to the distance that separates the nodes. Here, we present a Hybrid Firefly Glow-Worm Swarm Optimization (HF-GSO) guided routing strategy for preserving WSNs' low power footprint. An efficient fitness function based on firefly optimization is used to select the Cluster Head (CH) in this procedure. It aids in minimising power consumption and the occurrence of dead sensor nodes. After a cluster head (CH) has been chosen, the Glow-Worm Swarm Optimization (GSO) algorithm is used to figure out the best path for sending data to the sink node. Power consumption, throughput, packet delivery ratio, and network lifetime are just some of the metrics measured and compared between the proposed method and methods that are conceptually similar to those already in use. Simulation results showed that the proposed method significantly reduced energy consumption compared to the state-of-the-art methods, while simultaneously increasing the number of functioning sensor nodes by 2.4%. Proposed method produces superior outcomes compared to alternative optimization-based methods.

• 한국물환경학회지
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• 제33권4호
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• pp.403-408
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• 2017

In these days, wastewater reclamation and seawater desalination play essential role in addressing the challenge of worldwide water scarcity. Particularly, reverse osmosis (RO) for seawater desalination process is commonly used due to less energy consumption than conventional thermodynamic systems. However, membrane fouling and electrical energy consumption during operation of RO system for seawater desalination haver continued to be a obstruction to its application. In this study, therefore, wastewater secondary effluent is used for osmotic dilution of seawater. Firstly, fouling behaviour of RO by simulating wastewater effluent in osmotic dilution process was measured and we calculated energy consumption of overall desalination process by theoretical equations and commercial program. Our results reveal that RO membrane fouling can be efficiently controlled by pre-treatment systems such as nano filtration (NF) or forward osmosis (FO) process. Especially FO system for osmotic dilution process is a non-pressurized membrane system and, therefore, the operating energy consumption of overall desalination system was the lowest. Moreover, fouling layer on FO membrane is comparatively weak and reversible enough to be disrupted by physical cleaning. Thus, RO system with low salinity feed water through FO process is possible as a less energy consuming desalination system with efficient membrane fouling control.

• 정보처리학회논문지A
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• 제14A권1호
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• pp.55-62
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• 2007

모바일 기기와 같이 배터리에 의존적인 시스템에서 사용되는 임베디드 프로세서는 총 소모 전력의 많은 부분을 캐시에서 소모한다. 본 논문에서는 임베디드 프로세서용 고성능 선인출 데이터캐시의 저전력화 방안을 연구하였다. 고성능 선인출 데이터캐시에서 메모리 참조명령의 수행에 앞서 참조예측의 결과로 발생하는 선인출 명령은 캐시 적중률을 높여 메모리 참조 시간을 단축하는 반면 선인출 명령의 수에 비례하여 전력 소모가 증가한다. 본 논문에서는 선인출 데이터캐시에 태그이력표(tag history table)를 구비하여 병렬태그탐색을 최소화함으로써 전력 소모를 줄이는 캐시 구조를 제안하였다. 실험을 통해 확인한 결과 제안한 데이터캐시 구조가 기존 데이터캐시 구조에 비하여 수행 시간과 전력 소모를 모두 줄일 수 있음을 확인하였다.