• JSTS:Journal of Semiconductor Technology and Science
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• 제15권5호
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• pp.463-469
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• 2015

A vibration-based energy harvester and its equivalent circuit models have been reported. Most models predict voltage signals at harmonic excitation. However, vibrations in a natural environment are unpredictable in frequency and amplitude. In this paper, we propose a realistic equivalent circuit model of a frequency-up-converting impact-based piezoelectric energy harvester. It can describe the behavior of the harvester in a real environment where the frequency and the amplitude of the excitation vary arbitrarily. The simulation results of the model were compared with experimental data and showed good agreement. The proposed model can predict both the impact response and long term response in a non-harmonic excitation. The model is also very useful to analyze the performance of energy conversion circuitry with the harvester.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.971-974
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• 2014

본 논문은 최근의 에너지 절감의 사회적 관심을 반영한다. LED 시장은 지속적 성장을이어가고 있다. 그러나 현재 led 조명은 빛 에너지 변환율이 높지 않다.이러한 LED 조명에 대하여 빛 변환 에너지 절감 방법을 제시하고자 한다. 현재의 LED 조명은 전력 변화를 각각의 조명에서 이루어지므로 인한 변환 손실의 누적이 발생한다. 손실 누적 발생을 최소화 하여 에너지 손실 성능 개선을 얻을 수 있도록 한다.

• 한국전자통신학회논문지
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• 제10권6호
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• pp.691-698
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• 2015

최근, 전력산업에서는 지구 온난화에 대비하여 에너지 이용 효율 극대화하기 위한 방안으로 초전도 에너지 저장 장치에 큰 관심을 가지고 있다. 초전도 에너지 저장장치는 비 첨두시에 대량의 전기에너지를 손실 없이 자계 또는 운동 에너지의 형태로 저장하였다가 첨두시에 이를 다시 전기에너지로 변환하여 사용함으로서 피크부하의 균등화 및 순간정전 보상을 실현, 전기 에너지 이용 효율의 극대화를 기할 수 있다. 따라서 본 연구에서는 초전도 에너지 저장기술에 대한 개념, 연구개발 현황 및 그 적용 사례 등을 조사, 분석하여, 전력계통 적용 기반기술을 확립하고자 한다.

• 한국산학기술학회논문지
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• 제12권5호
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• pp.2048-2053
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• 2011

본 논문에서는 도어의 회전운동에 의해서 발생하는 기계에너지를 전기에너지로 변환시켜 에너지를 획득하는 시스템을 제안한다. 에너지를 획득하는 방법으로 2종류의 에너지 하베스터을 논의한다. 첫 번째, 도어의 회전축과 발전장치의 축을 기어장치로 직접 연결하여 발전하는 기어 축결합 에너지 하베스터, 두 번째로는 도어 선단을 발전장치의 스트링으로 연결하여 발전하는 스파이럴스프링 에너지 하베스터이다. 이 2종류의 하베스터를 제작하여 실험을 수행하며, 이 결과를 통해서 제안한 에너지 하베스터의 유효성을 나타낸다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.827-830
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• 2006

With recent advanced in portable electric devices, wireless sensor, MEMS and bio-Mechanics device, the new typed power supply, not conventional battery but self-powered energy source is needed. Particularly, the system that harvests from their environments are interests for use in self powered devices. For very low powered devices, environmental energy may be enough to use power source. In the generality of cases, these energy harvesting systems are used in the piezoelectric materials as mechanisms to convert mechanical vibration energy into electric energy. Through the piezoelectric materials, the ambient vibration energy could be used to prolong the power supply or in the ideal case provide endless energy f9r the devices. Therefore, the piezoelectric power harvesting cantilever beam is developed. Also, the output voltage and power are predicted in this study. We also discuss the developing system of the piezoelectric energy scavenger. An experimental verification of the model is also performed to ensure its accuracy.

• 제어로봇시스템학회논문지
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• 제10권11호
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• pp.1006-1011
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• 2004

Carbon nanotubes have outstanding properties which make them useful for a number of high-technology applications. Especially, single-walled carbon nanotube (SWNT), working under physical conditions (in aqueous solution) and converting electrical energy into mechanical energy directly, can be a good substitute for artificial muscle. The carbon nanotube structure simulated in this paper is an isotropic cantilever type with an adhesive tape which is sandwiched between two SWNTs. For predicting the geometrical and physical parameters such as deflection, slope, bending moment and induced force with various applied voltages, the analytical model for a 3 layer bimorph nanotube actuator is developed by applying Euler-Bernoulli beam theory. The governing equation and boundary conditions are derived from energy Principles. Also, the brief history of carbon nonotube is overviewed and its properties are compared with other functional materials. Moreover, an electro-mechanical coupling coefficient of the carbon nanotube actuator is discussed to identify the electro-mechanical energy efficiency.

• KIEAE Journal
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• 제16권2호
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• pp.11-16
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• 2016

Purpose: International efforts to save Earth's environment against global warming and environmental pollution have been made in many countries. Energy consumption of buildings has been continuously increasing, and it has been over 40% of total energy consumption in the world. Energy consumption of buildings in Korea reaches 24% of total energy consumption. So, Korea government has executed building energy rating systems to control energy consumption of buildings. Method: This study was carried out to evaluate the energy performance of apartment unit plans according to converting balconies into living areas. For the study, six types of input models were made. Two input models(SP1 and SP 2) were the standard units that balcony areas were not converted into living areas, and four ones(EP 1, EP 2, EP 3 and EP 4) were the extended unit plans that balcony areas were turned into living areas. All of them were simulated with ECO2 software to assess building energy efficiency. Result: According to the results, the energy performance of the EP 2 and EP 4 models were 21. 8% higher than SP 1 model and 9.2% higher than SP 2 model.

• 자원ㆍ환경경제연구
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• 제32권2호
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• pp.127-147
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• 2023

본 연구는 정부의 탄소중립 정책 중 하나인 화력발전을 신재생에너지로 대체하는 경우 에 대한 경제적 파급효과를 분석하는 것을 목적으로 한다. 이러한 분석을 위해 화력발전을 신재생에너지로 100% 대체하는 경우를 시나리오 A로 설정하고, 60%로 대체하는 경우를 시나리오 B로 설정한다. 또한 이렇게 화력발전을 신재생에너지로 대체할 때 비용이 발생하게 되는데 현행과 동일한 비용인 경우를 시나리오 1, 현행보다 비용이 120% 증가한 경우를 시나리오 2로 설정한다. 따라서 화력발전을 신재생에너지로 전환할 때 시나리오는 크게 이와 같이 4가지 경우로 정리된다. 화력발전을 신재생에너지로 전환하는 경우, 화력발전의 생산유발계수는 시나리오와 관계없이 현행 수준보다 감소하는 것으로 나타났다. 그러나 화력발전을 신재생에너지로 100% 전환하는 경우 부가가치유발계수와 온실가스배출량 유발계수는 현행 수준보다 감소한 반면 화력발전을 신재생에너지로 60% 대체하는 경우 부가가치유발계수와 온실가스배출량 유발계수는 현행 수준보다 증가했다. 또한 대부분의 업종의 온실가스배출량 유발계수는 감소하는 것으로 나타난 반면 생산유발계수와 부가가치유발계수는 증가하는 것으로 나타났다. 정부 정책의 목적은 화력발전을 신재생에너지로 전환시켜 온실가스배출량을 축소시키는 것이기 때문에 시나리오 화력발전을 신재생에너지로 100% 전환하는 경우가 더 적합한 것으로 보인다. 다만, 이로 인해 일부 업종의 생산유발계수와 부가가치유발계수가 감소하는 부작용이 발생하므로 이를 해결하기 위한 정부의 지원 정책이 필요하다.

• Applied Science and Convergence Technology
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• 제23권5호
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• pp.221-239
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• 2014

The global demand for energy has been increasing since past decades. Various technologies have been working to find a suitable alternative for the generation of sustainable energy. Photovoltaic technologies for solar energy conversion represent one of the significant routes for the green and renewable energy production. Despite of remarkable improvement in solar cell technologies, the generation of power is still suffering with lower energy conversion efficiency, high production cost, etc. The major problem in improving the PV efficiency is spectral mismatch between the incident solar spectrum and bandgap of a semiconductor material used in solar cell. Luminescent materials such as rare-earth doped phosphor materials having the quantum efficiency higher than unity can be helpful for photovoltaic applications. Quantum cutting phosphors are the most suitable candidates for the generation of two or more low-energy photons for the absorption of every incident high-energy photons. The phosphors which are capable of converting UV photon to visible and near-IR (NIR) photon are studied primarily for photovoltaic applications. In this review, we will survey various near IR quantum cutting phosphors with respective to their synthesis method, energy transfer mechanism, nature of activator, sensitizer and dopant materials incorporation and energy conversion efficiency considering their applications in photovoltaics.

• 비파괴검사학회지
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• 제32권6호
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• pp.661-668
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• 2012

Wireless sensor network is one of prospective methods for railway monitoring due to the long-term operation and low-maintenance performances. How to supply power to the wireless sensor nodes has drawn much attention recently. In railway monitoring, the idea of converting ambient vibration energy from vibration of railway track induced by passing trains to electric energy has made it a potential way for powering the wireless sensor nodes. In this paper, a bimorph cantilever piezoelectric energy harvester was designed based on a single degree-of-freedom model. Experimental test was also performed to validate the design. The first natural frequency of the bimorph piezoelectric energy harvester was decreased from 117.1 Hz to 65.2 Hz by adding 4 gram tip mass to the free end of the 8.6 gram energy harvester. In addition, the power generation of the piezoelectric energy harvester with 4 gram tip mass at resonant frequency was increased from 0.14 mW to 0.74 mW from $2.06m/s^2$ base excitation compared to stand-alone piezoelectric energy harvester without tip mass.