• 한국전기전자재료학회논문지
• /
• 제26권11호
• /
• pp.846-851
• /
• 2013

Recently, energy harvesting technologies are considered as the great alternatives to reduce the dependency on secondary batteries. In this paper, we proposed PCB type energy harvester which can be directly integrated with other electronic components on same board. To form the three dimensional coil structure, two PCBs with patterned metal lines are solder bonded. For magnetic induction, inside of coil structure was filled with magnetic substance and rotary motioned external magnets are applied to near the harvester. The effects of metal wire width on PCB, thickness of magnetic substance, and frequency of rotary motion on energy harvesting performance are analyzed by computer simulation and experiments. Experimental results showed 29.89 ${\mu}W$ of power generation performance at the frequency of 5.2 Hz and it is shown that designed harvester can be effectively applied on vibration environment with very limited frequency.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제17권4호
• /
• pp.1123-1146
• /
• 2023

In South Korea, there have been many studies on efficient building-energy management using renewable energy facilities in single zero-energy houses or buildings. However, such management was limited due to spatial and economic problems. To realize a smart zero-energy city, studying efficient energy integration for the entire city, not just for a single house or building, is necessary. Therefore, this study was conducted in the eco-friendly energy town of Chungbuk Innovation City. Chungbuk successfully realized energy independence by converging new and renewable energy facilities for the first time in South Korea. This study analyzes energy data collected from public buildings in that town every minute for a year. We propose a smart city building-energy management model based on the results that combine various renewable energy sources with grid power. Supervised learning can determine when it is best to sell surplus electricity, or unsupervised learning can be used if there is a particular pattern or rule for energy use. However, it is more appropriate to use reinforcement learning to maximize rewards in an environment with numerous variables that change every moment. Therefore, we propose a power distribution algorithm based on reinforcement learning that considers the sales of Energy Storage System power from surplus renewable energy. Finally, we confirm through economic analysis that a 10% saving is possible from this efficiency.

• KIEAE Journal
• /
• 제13권5호
• /
• pp.51-57
• /
• 2013

Energy saving starts by knowing how much energy is being consumed. A building factor is easier than any other things in energy saving. Since, especially, it is closely connected with user's space-use-patterns and manager's utility-operation-style. An energy metering system lets building users know about energy consumption pattern in buildings and measure energy in real time. Development and materialization of metering systems need more careful plans, so that they depend on a demand of individual facilities and available infrastructures they used to use. But, so far, there is no guidelines how to install metering systems. This paper suggested how to install meters and researched a method for how to analyze by using metered data. For that, Green Building in KIER is used as a test bed. As the results, nevertheless the smallest number of meters is basically one for the whole building energy measuring, it is too limited in analysis. So we needed to add the sort of fuel and utility types and found that it depends on all cases. For this reasons, a guideline should be created in order to install meters as soon as possible. It would be suggest a way to save more energy in building factor.

• 한국통신학회논문지
• /
• 제37권3B호
• /
• pp.149-157
• /
• 2012

WSN 환경의 센서노드는 정보를 수집하고 베이스스테이션으로 전달한다. 베이스스테이션은 인증되지 않은 노드로부터 전달받은 데이터를 신뢰하기 어렵다. 따라서 다양한 방법으로 노드를 인증하고, 데이터의 안전성을 판단하는 방식들이 연구되고 있다. 기존 AM-E[12] 방식에서는 노드인증 후에 데이터를 전달한다. 이때 센서노드는 베이스 스테이션과 직접 AREQ/AREP 메시지를 통신하는 과정에서 인증메시지 송수신으로 인해 많은 에너지를 소비하게 된다. 또한 모든 노드는 인증을 위해 베이스스테이션과 직접 통신과정을 거치며 한정된 에너지를 과다하게 소비하는 문제점을 갖는다. 따라서 이 논문에서는 AM-E 방식과 동일한 보안성을 제공하면서 센서노드의 에너지소비를 최소화할 수 있는 IDE 기반의 계층적 노드인증 프로토콜을 제안한다. 제안방법은 안전성 측면에서는 기존 방식과 같이 메시지 재전송공격이나 메시지의 무결성 보장을 유지하면서 통신에 참여하는 노드수가 AM-E 방식보다 약 39% 증가되어 전체 네트워크 생명주기를 연장함으로 에너지 효율성을 증가시켰다.

• 한국대기환경학회지
• /
• 제28권2호
• /
• pp.109-118
• /
• 2012

Ahead of the second basic plan which starts in 2015, tasks needed to improve air quality and encourage green growth in the Seoul Metropolitan Area have been investigated. To date, many research findings indicate that climate change is ongoing and continues to accelerate in the Northeast Asia due to several factors, including unparalleled anthropogenic air emissions from China. An intensive field study is proposed that would target the Seoul Metropolitan Area and would be conducted in collaboration with the international scientific community. While focused on environmental issues in Korea, this study would also benefit the international community by providing insights that can be applied to address similar problems around the world. In addition to the basic plan's emphasis on improving air quality, there is a need to promote green growth through environment-friendly development. It is proposed that green growth be interpreted as a comprehensive concept, targeting all environmental pollution, rather than being limited to low-carbon goals. It is further proposed that the success of environment-friendly development be measured in terms of risk reduction, energy and resources conservation, economic benefits, and employment expansion.

• Carbon letters
• /
• 제1권2호
• /
• pp.82-86
• /
• 2000

The present research was undertaken to evaluate the possibility of water purification filter with activated carbon fibers (ACFs) using a very low cost precursor consisting of phenolic resin coated on glass fibers. The simplified procedure involving coating, curing and activation and a very low cost glass fiber as a raw material were adopted in order to reduce manufacturing cost. The breakthrough curves of the manufactured ACFs and the commercial activated carbon (AC, Calgon F-200) were investigated in the initial concentration range from 19 to 49 ppm for benzene, toluene and ethylbenzene. From breakthrough profiles, the manufactured ACFs had significantly faster adsorption kinetics than the AC. Especially the benzene breakthrough curves, the manufactured ACF (13 g of ACF with 32% of carbon on the glass) was over the limited level (5 ppb) after flowing of 32 l at initial concentration of 15 ppm, while the commercial AC was shown about 3 ppm in initial adsorption.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2004년도 추계학술대회 논문집
• /
• pp.522-526
• /
• 2004

High cost of crude oil imposes a heavy burden on vehicle users. Thus, much efforts are given to the development of alternative energies in advanced countries as well as our country. Among them, fuel cell is emerged as the most promising one for transportation. There is no harmful emission with hydrogen energy of which sources are abundant on the earth. The use of both fuel cell with self-generating system and electromanetic guidance system will be able to make urban track rapid transit operate even in the city areas of very limited infrastructure space with flexibility and on time accessibility. The high efficiency is also expected with clean environment and easy riding for both the old and the handicapped.

• 반도체디스플레이기술학회지
• /
• 제21권3호
• /
• pp.1-6
• /
• 2022

Modern computer systems usually have special hardware for operations used in deep learning workload even edge computing environment. Non-volatile memories (NVMs) have been considered for alternative memory storage because they consume little static energy and occupy small area. However, there is a problem for NVMs to be directly adopted. An NVM cell has limited write endurance, so that the lifetime of NVM-based memory system is much shorter than that of conventional memory system. To overcome this problem for the deep learning system, this paper proposes a novel method to extend the lifetime based on the analysis of the deep learning workloads. If an incoming block has more than a predefined number of frequently used values, the cacheline is defined as write friendly block. During the victim selection, the cacheline has lower possibility to be chosen as victim. The experimental results show that the lifetime is increased by about 50% and energy consumption is decreased by 3% with a little performance hurt.

• 상하수도학회지
• /
• 제32권2호
• /
• pp.131-143
• /
• 2018

Phosphorus (P) is a limited, essential, and irreplaceable nutrient for the biological activity of all the living organisms. Sewage sludge ash (SSA) is one of the most important secondary P resources due to its high P content. The SSA has been intensively investigated to recover P by wet chemicals (acid or alkali). Even though $H_2SO_4$ was mainly used to extract P because of its low cost and accessibility, the formation of $CaSO_4$ (gypsum) hinders its use. Heavy metals in the SSA also cause a significant problem in P recovery since fertilizer needs to meet government standards for human health. Therefore, P recovery process with selective heavy metal removal needs to be developed. In this paper some of the most advanced P recovery processes have been introduced and discussed their technical characteristics. The results showed that further research is needed to identify the chemical mechanisms of P transformation in the recovery process and to increase P recovery efficiency and the yields.

• 한국해양환경ㆍ에너지학회지
• /
• 제5권3호
• /
• pp.10-15
• /
• 2002

반복적으로 나타나는 고정된 이차원 모래언덕에 의하여 생성되는 난류유동장을 해석하기 위하여 PIV 기법을 적용하였다. PIV 기법의 사정을 위하여 LDV 실험자료와 결과를 비교하였는데 유동박리 및 큰 전단유동 영역에까지 좋은 결과를 보여주었다 레이저 시트로 조사된 이차원 단면의 흐름을 이미징 테크닉으로 해석하는 PIV 방법이 갖는 고유의 단점들을 완전히 해결하지는 못하였으나, 전체적으로 LDV 결과와 매우 잘 일치하고 있었으며 특히 Two-point correlation 이나 Quadrant analysis와 같이 고차항까지를 추적할 수 있었다 특히 기존의 일점계측법으로는 해석이 불가능한 순간유동장의 가시화 및 정량화가 가능하였으며 Time-series로 변환시킨 PIV 데이터의 신뢰성도 확인이 가능하였다. 추후 토사이동과 같은 복잡한 유동해석에도 본 기법을 그대로 활용할 수 있으리라 기대한다.