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Direct-current triboelectric nanogenerator via water electrification and phase control
Kim, Taehun,Kim, Dae Yun,Yun, Junseo,Kim, Banseok,Lee, Seong Hyuk,Kim, Dongseob,Lee, Sangmin Elsevier 2018 Nano energy Vol.52 No.-
<P><B>Abstract</B></P> <P>The recent reputational excellence of triboelectric nanogenerators is based on the idea that they have overcome many limitations for traditional energy harvesting methods. However, in many important respects, these nanogenerators show little promise in addressing the limitations of device efficiency, and in some cases, they threaten the material lifetime. To overcome both efficiency and durability issues, we propose a novel mechanism that generates a DC output via water electrification based on phase control to enhance the sustainability of nanogenerators. Our demonstrations here can enable breakthrough impacts by enhancing device durability with fluid control, generating DC output for energy-loss reduction and providing feasibility with an application model. The advantages of our fluid-controllable DC power nanogenerator can be integrated easily with every energy-harvesting device, thus making it easy for energy-related disciplines to overcome major issues in the more practical way.</P> <P><B>Highlights</B></P> <P> <UL> <LI> It is the report on a new triboelectric nanogenerator (TENG) using water electrification and phase control techniques for a direct-current (DC) power source. </LI> <LI> A numerical simulation of the multiphase flow was conducted to study the electric regimes in the given energy-harvesting system. </LI> <LI> The introduction of our DC-TENG techniques makes it possible to resolve durability and efficiency issues. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
김태훈(Kim, Taehun),김거화(Kim, Geohwa),김동언(Kim, Dongeun),정진화(Chung, Chinhwa),박현철(Park, H.C.) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.11
포항공과대학교 풍력특성화대학원에서는 3MW급 외전형 영구자석 동기발전기 설계를 진행하고 있다. 여기서 외전형이란 RFPM 발전기에서 회전자가 바깥에서 회전하는 형태로 기존의 RFPM 발전기와 비교하여 같은 공극직경에 더 많은 자석을 채택할 수 있고, 회전자와 터빈 블레이드를 직접 연결이 가능하다. 또한, 회전자를 외부에 노출 시킬 수 있으므로 냉각에 유리한 면이 있다. 설계 변수 중 출력과 회전수를 고정시키고 각 극수와 공극 직경, 전압을 변화함에 따른 전기적 특성을 비교하고, 그 중 최적의 모델을 선택한다. 선택된 모델의 전자기장 해석, 손실 계산, 열분석을 수행한다. 본 논문에서는 각 경우에 따른 결과를 비교하고 최적 모델에 대한 해석 결과에 대해 요약한다.
김태훈(Kim, Taehun),김거화(Kim, Geohwa),원정현(Won, Junghyun),이수호(Lee, Sooho),김동언(Kim, Dongeun),정진화(Chung, Chinwha),박현철(Park, H.C.) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06
포항공과대학교 풍력특성화대학원에서는 STX Windpower의 풍력발전기 국산화 사업의 일환으로 2MW 직접 구동형 영구자석 동기발전기의 설계를 변경 하였다. 정격 출력 2.3MW급으로 정격 RPM은 16.5, 고정자 내경은 2.1m로 128극을 가지고 있다. 본 설계 발전기는 STX93 모델을 기반으로 하고 있으며, 기존 발전기보다 더 compact하고 더 높은 효율의 발전기로 설계 변경하였다. 본 논문에서는 발전기 물리 설계와 그에 따른 전자기 해석 및 열 분석을 수행하고 손실을 계산한다. 또한, 그 결과와 절차에 대하여 요약하고 기존 발전기와 설계 발전기를 비교 분석한다.
김태훈(Kim Taehun),김선웅(Kim Seonwoong),김종인(Kim Jongin),박지연(Park Jiyeon) 한국농촌경제연구원 2017 한국농촌경제연구원 기본연구보고서 Vol.- No.-
Research Background It has been about 20 years since the direct payment schemes were implemented in Korea and the schemes have played an essential role in the agricultural sector as a policy instrument. However, there have been some skeptical views on the effectiveness of the direct payment schemes, especially on whether the purpose of the schemes at the time of introduction is still valid. The goal of this study consists of two parts: to evaluate the effectiveness of the schemes and suggest an improvement direction for the current direct payment schemes in the first year and to set up a specific plan, especially for the schemes on rice paddies (Fixed and Variable Rice Direct Payment; FRDP and VRDP) and dry fields (Upland Field Direct Payment; UFDP), considering the results of the first-year study in the second and last year. Research Methodology In this study, several research methodologies are applied depending on the target subjects as below. · Literature review and expert group meetings on the pollution levels of agricultural land and water. · Statistical analysis of farm household economy and food balance sheets · Questionnaires on the status of farm input use, farmers" acceptance rate for the revised cross-compliance, and willingness-to-pay on agricultural multifunctionality depending on whether the consumers get educated about the multifunctionality by using choice experiments. Conclusion and Implication The Farmland Management Direct Payment scheme (FMDP) should include FRDP, UFDP, and some of VRDP and the payments from the scheme are paid to farmers as a reward for providing the agricultural multifunctionality, especially for food security, environmental preservation, and sustainable agriculture. FMDP aims to relieve the unequal distribution of the agricultural budget between direct payments for rice paddies and the others and also eliminate the extra incentive for rice production. The cross-compliance (CC) for FMDP is as follows: First, farmers should preserve their farmland to cultivate crops. Second, farmers should record the use of agro-materials, especially fertilizer and chemicals. Third, farmers should participate in the educational courses about multifunctionality and cross-compliance. Last, dry field farmers should apply some specific agricultural techniques to reduce soil erosion by water. The acceptance rate for the suggested cross-compliance of FMDP is more than 80%, which means the CC of FMDP is acceptable and realizable to farmers. This is because more than 60% of farmers have already recorded their agricultural input use and they recognize that the educational course is useful for not only getting the remuneration of the direct payment scheme but also increasing their agricultural productivity. To estimate the appropriate remuneration ratio between the direct payments for rice paddies and UFDP, the farmer"s family labor income and the contribution ratio of those farmlands for annual food supply per capita per day are considered. Based on the results, the remuneration ratio between those two schemes should be the same, considering the benefit-cost efficiency of carrying out the policy, even though the ratio of UFDP is slightly higher in both criteria. To conduct FMDP, it is a prerequisite for taxpayers or interest groups to understand the importance of agricultural multifunctionality and to agree with supporting farmers to provide ‘more’ multifunctionality. To figure out the way for taxpayers to support FMDP, a survey was conducted based on choice experiments. The result shows that the participants who got education about agricultural multifunctionality show a 20% higher WTP for multifunctionality compared to the participants who did not.