• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04b
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• pp.53-54
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• 2009

Nowadays, source of MEMS, USN, Hybrid parts pay attention to energy harvesting. On this paper, energy harvesting was studied using piezoelectric effect. And, piezoelectric generator was designed and fabricated. Generators were designed by FEM simulation program and generators were made by attaching cymbal type metal plates on upper and bottom sides of a disc type piezoelectric ceramic. Using fabricated generators, output voltages dependant on thickness of ceramic, displacement of vibration, frequency of vibration were measured.

• Journal of Urban Science
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• v.9 no.1
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• pp.1-6
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• 2020

The thermoelectric characteristics of alkali activated slag composites containing multi-walled carbon nanotubes (MWCNT) was investigated in the present study. Three different MWCNT contents and exposed temperatures were considered, and their thermoelectric-related properties and internal structures were analyzed. It was found that the alkali activated slag composite with MWCNT 2.0 wt.% and the exposed temperature of 150℃ were the optimal condition to obtain the highest Seebeck coefficient and power factor. Based on the feasibility study, the extended size thermoelectric module with 130 elements was fabricated, and tested the electricity production capacity. Consequently, the present thermoelectric module produced 30.83 ㎼ of electricity at ∆T=178.4℃.

• Journal of Sensor Science and Technology
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• v.19 no.4
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• pp.313-319
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• 2010

Vibration energy harvesting is an attractive technique for potential powering of low power devices such as wireless sensors and portable electronic applications. Most energy generator developed to date are single vibration frequency based, and while some efforts have been made to broaden the frequency range of energy harvester. In this work, The effect of energy harvesting were investigated at various vibration frequencies, vibration beams, vibration point and test masses. The maximum output voltage of the bimorph piezoelectric cantilever was shifted according to vibration point. Vibration frequency with maximum output voltage decreased with the increasing length of vibration beam and increasing test mass. The sample with vibration beam length 0.5 L generated a peak output voltage of 32 $V_{rms}$ and shows a 45 % increase in voltage output in comparison to the corresponding original bimorph. It was found that a piezoelectric bimorph has a possibility to be as the energy harvesting cantilever, which is successfully tuned over a vibration frequency range to enable a maximum harvesting energy.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.31-34
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• 2018

This paper presents a low-power buck-boost converter for multi-input energy harvesting systems. The designed circuit combines the energy harvested from three input channels in real time and stores it in a storage capacitor. The structure of the buck-boost converter is simplified by using one external inductor and applying time division technique using an arbiter. In addition, to improve the efficiency of the system, the controller circuits of the converter are designed so that current consumption is minimized. The proposed circuit is designed with $0.35{\mu}m$ CMOS process. Simulation results show that the designed circuit consumes up to 490nA of current when all three input channels are active, and the maximum power efficiency is 92%. The chip area of the designed circuit is $1310{\mu}m{\times}1100{\mu}m$.

• Horticultural Science & Technology
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• v.16 no.2
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• pp.233-235
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• 1998

Energized-functional water (EFW) and powder (EFP) were manufactured by Kyungwon Institute of Life Science, Seoul, through a series of processes; tap water ultra-purification energy imprinting with catalysts in platinum columns mixing energy-imprinted water + activated zeolites + photosynthetic bacteria fermenting at $25^{\circ}C$ filtering EFW and/or EFP. A single application of EFP to soil under tree canopy before bud burst, combined with three EFW applications to soil during growth of 'Fuji' apples (Malus domestica Borkh.) resulted in a higher Ca concentrations in fruit skins and flesh, and lower Ca and N concentrations in leaves and shoot-bark tissues. EFW also stimulated the net photosynthesis of leaves and root activity. Soluble solid concentrations (SSC) and anthocyanin levels of fruits were also significantly increased at harvest, producing greater firmness and less core browning during storage at $0^{\circ}C$. However, there was no significant difference in titratable acidity of fruit juice between the EFW treatment and the controls.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.587-590
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• 2009

New onion hybrid cultivar, "Yeongpunghwang" was developed from cross between "MOS8", male sterile line and "Mokpo 11", pollen line by Mokpo Sub-Station, National Institute of Horticultural & Herbal Science, RDA in 2008. The crossing line was performed yield test in 2003. IT was evaluated as "Mokpo 11" in the regional yield trial test(RYT) from 2006 to 2008 during three years. This line is semi-erect plant growth type and has green leaf colour. It has broad ovate bulb shape and yellow skin colour in bulb characteristics. Plant height, leaf number, and bolting rate was 78cm, 7.9, and 3.9%, respectively. Lodging date as harvesting indicator was on 26 May. The yield potential of "Yeongpunghwang" was out-yielding 6% compare to check variety ("Sunpower") by with 8,344 kg/10a in RYT. It showed moderated cold hardness in all regional location which was conducting RYT, including Muan, Goheung, Changyeong and Andong. So this variety was recommend as a leading variety at southern area of korea.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.3
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• pp.619-626
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• 2019

The advances of semiconductor and circuitry technology dovetailed with nano processing techniques have further enhanced micro-miniaturization, sensitivity, longevity and reliability in MID(Medical Implant Device). Nevertheless, one of the remaining challenges is whether power can sufficiently and continuously be supplied for the operation of the MID. Self-powered MID that harvest biomechanical energy from human motion, respiratory and muscle movement are part of a paradigm shift. In this paper, we developed a rechargeable pacemaker through self-power generation with the triboelectric nanogenerator. We demonstrate a fully implanted pacemaker based on an implantable triboelectric nanogenerator, which act as a storage as well as active movement on a large-animal(dog) scale. The self-power pacemaker harvested from animal motion is 2.47V, which is higher than the required pacemaker device sensing voltage(1.35V).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.11
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• pp.1679-1685
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• 2022

In this paper, we propose an optimal multi-hop transmission scheme to maximize the end-to-end data rate from the source to the destination node in a wireless powered communication network. The frame structure for multi-hop transmission is presented to transmit multi-hop data while harvesting energy. Then, the transmission time of each node that maximizes the end-to-end transmission rate is determined through mathematical analysis in consideration of different harvested energy and link quality among nodes. We derive an optimization problem through system modeling of the considered wireless powered multi-hop transmission, and prove that there is a global optimal solution by verifying the convexity of this optimization problem. This analysis facilitates to find the optimal solution of the considered optimization problem. The proposed optimal multi-hop transmission scheme maximizes the end-to-end rate by allocating the transmission time for each node that equalizes the transmission rates of all links.

• Journal of Energy Engineering
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• v.25 no.1
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• pp.23-28
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• 2016

In spite of various merit of algae as biofuel, the production cost of algae is a considerable obstacle for commercialization. The concurrent development of essential technologies is needed for the cultivating, harvesting, extracting and energy transformation. The production cost of algae biofuel has still higher than that of the other commercial biofuel. The major research activity has been focused on the cultivating and the research of other processes has been done with relatively lower activity. It is difficult to separate the algae from water because of the similar magnitude of density each other. The agglomeration and extracting of algae with the hybrid technology using ultrasonic wave is rare effect of environmental hazard and also it is appropriate technology for the next generation energy resources. The present research is investigated for the effective separation of algae from water with the ultrasonics wave. The aim of the present research is focused on the establishment of optimal design of algae agglomeration system. For this purpose, the computational fluid dynamic analysis has been conducted in the flow field with ultrasonic wave and algae flow to clarify the mechanism of algae separation by ultrasonic wave.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.306-306
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• 2010

21 세기는 언제, 어디에서, 누구나가 정보를 자유롭게 염가에 이용할 수 있는 유비쿼터스 정보사회가 될 것으로 예상하고 있다. 이러한 유비쿼터스 사회가 실현되기 위해서는 필연적으로 대두되고 있는 과제가 에너지 공급원의 문제이다. 휴대용 전자제품이나 소형 에너지 공급원으로 지금까지 주로 전지가 사용되어 왔지만 이것들은 교환 및 충전이 불가피하다. 이러한 불편함을 개선하기위해 교환과 충전이 불필요하거나 아주 장시간동안 공급해주는 형태의 에너지 공급원의 필요성이 대두되고 있다. 이러한 에너지 공급원으로 최근에 많은 연구가 되고 있는 것이 주위의 환경으로부터 버려지는 에너지를 수확(harvesting)하여 전력으로 변환하는 에너지 하베스팅 (energy harvesting)기술이 연구 개발되고 있다. 에너지 하베스팅 응용을 위해서 사용되어지는 압전 세라믹스는 전압출력계수 ($g_{33}$)가 커야하는데 이것은 압전상수 ($d_{33}$)와 유전상수 (${\varepsilon}_{\tau}$)의 값에 영향을 받는 것으로 알려져있다. 그 중에서 우수한 전기적 특성 때문에 PZT를 기반으로 하는 압전 세라믹스가 사용되어져왔다. 그러나 Pb의 높은 유독성과 Pb를 포함하는 제품들의 처분문제들로 인해 제조에 관한 많은 문제점들을 지니고있다. 그리하여, Pb를 포함하지 않는 Pb-free계에 관한 연구가 전세계적으로 활발히 진행되고 있다. 다양한 Pb-free계 후보자들 가운데 $K_{0.5}Na_{0.5}NbO_3$ (KNN)는 높은 큐리온도와 좋은 강유전 특성 및 압전특성 때문에 PZT를 대체할 가장 장래성있는 대안들 중의 하나로 고려되고 있다. 그러나 고온에서 알칼라인 원소들의 높은 휘발성 때문에 보통의 소결공정으로는 소결이 잘되고 치밀한 세라믹스를 얻기가 어렵다. 많은 연구에서 KNN 세라믹스의 소결성을 개선하기 위하여 강유전 또는 반강유전체인 $SrTiP_3$와 $LiTaO_3$를 고용체 형성에 포함시키고 또한 $K_4CuNb_8O_{23}$, $MnO_2$, CuO등과 같은 소결조제를 첨가하여 압전 특성과 소결성을 개선시켰다. 따라서 본 연구에서는 비화학양론적 (1-X)[$[(K_{0.5}Na_{0.5}]_{0.97}(Nb_{0.96}Sb_{0.04})O_3]$ + 0.008CuO + 0.2wt% $Ag_2O$ + X $CeMnO_3$의 조성을 사용하여 A사이트와 B 사이트에 각각 Ce이온과 Mn 이온의 치환량을 변화하여 그에 따른 유전 및 압전특성을 조사하였다.