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Piezoelectric polymer-based roadway energy harvesting via displacement amplification module
Shin, Youn-Hwan,Jung, Inki,Noh, Myoung-Sub,Kim, Jeong Hun,Choi, Ji-Young,Kim, Sangtae,Kang, Chong-Yun Elsevier 2018 APPLIED ENERGY Vol.216 No.-
<P><B>Abstract</B></P> <P>Recent research efforts show that piezoelectric polymers such as PVDF are competitive alternatives to the conventional piezoelectric ceramics. While possessing extraordinary toughness and fatigue resistance, however, piezoelectric polymers suffer from limited applications due to a large amount of deformation required for high power output. Here, we design and demonstrate a PVDF-based, high-power piezoelectric module installed on a local highway, for the first time. The module contains a bridge-type displacement amplification capability, demonstrating the 2.5 mm vertical displacement converted into 13 mm horizontal deformation, suitable for the uninterrupted driving experience. We provide the design guidelines and optimization strategies for the module, in terms of the piezoelectric power output. With 80 bimorph-shaped energy harvesters, the module achieves up to 16.5 W/m<SUP>2</SUP> energy density when the test vehicle passes by at 80 km/h. The matching impedance decreases with vehicle speed, suggesting that different matching impedance should be used for highway and local roadways. The output power exhibits a linear relation to the vehicle speed and weight, implying the module’s potential application as a self-powered speed sensor. The study demonstrates that PVDF-based energy harvesters provide a competitive power output at small vertical displacements with relevant module design, making the tough piezoelectric materials suitable for efficient and durable roadway energy harvesting.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PVDF-based energy harvesting module is demonstrated on local highway in Korea. </LI> <LI> The module features displacement amplification unit for uninterrupted driving. </LI> <LI> The power output reaches up to 16 W/m<SUP>2</SUP> and scales with the speed of the vehicles. </LI> <LI> The module may also be used as a self-powered speed sensor. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
<i>T-Chain</i>: A General Incentive Scheme for Cooperative Computing
Shin, Kyuyong,Joe-Wong, Carlee,Ha, Sangtae,Yi, Yung,Rhee, Injong,Reeves, Douglas S. Institute of Electrical and Electronics Engineers, 2017 IEEE/ACM transactions on networking Vol.25 No.4
<P>In this paper, we propose a simple, distributed, but highly efficient fairness-enforcing incentive mechanism for cooperative computing. The proposed mechanism, called triangle chaining (T-Chain), enforces reciprocity to avoid the exploitable aspects of the schemes that allow free-riding. In T-Chain, symmetric key cryptography provides the basis for a lightweight, almost-fair exchange protocol, which is coupled with a pay-it-forward mechanism. This combination increases the opportunity for multi-lateral exchanges and further maximizes the resource utilization of participants, each of whom is assumed to operate solely for his or her own benefit. T-Chain also provides barrier-free entry to newcomers with flexible resource allocation, allowing them to immediately benefit, and, therefore, is suitable for dynamic environments with high churn (i.e., turnover). T-Chain is distributed and simple to implement, as no trusted third party is required to monitor or enforce the scheme, nor is there any reliance on reputation information or tokens.</P>
Flexible piezoelectric polymer-based energy harvesting system for roadway applications
Jung, Inki,Shin, Youn-Hwan,Kim, Sangtae,Choi, Ji-young,Kang, Chong-Yun Elsevier 2017 APPLIED ENERGY Vol.197 No.-
<P>Interest in energy harvesters has grown rapidly over the last decade. The research effort in large-scale energy harvesting has mainly focused on piezoelectric ceramic based devices, due to its high piezoelectric constants. In this study, we demonstrate a piezoelectric energy harvester module based on polyvinylidene fluoride (PVDF) polymer for roadway applications. Flexible energy harvesters are fabricated with PVDF films and it exhibited stable performance and durability over the repeated number of bending cycles. In order to structurally optimize the design, finite element analysis was performed on two possible module configuration, with detailed input conditions on how the flexible energy harvester must be bent. A piezoelectric energy harvester module is then constructed with the fabricated unit energy harvesters inserted in the vertical direction, with initial radii of curvature as high as possible. The module was tested with a model mobile load system (MMLS3) and exhibited up to 200 mW instantaneous power output across a 40 k Omega resistor. The power output scaled linearly with the number of parallel connected harvesters. The calculated power density at this impedance reaches up to 8.9 W/m(2), suggesting that the flexible energy harvesters based on the piezoelectric polymers may provide energy density as high as those based on piezoelectric ceramics. (C) 2017 Elsevier Ltd. All rights reserved.</P>
Yoo, Hyeonggeun,Shin, Hyunkwon,Sim, Boyeon,Kim, Sangtae,Lee, Myeongkyu IOP Pub 2009 Nanotechnology Vol.20 No.24
<P>Thin film patterning by the conventional lithographic technique requires a number of steps including the deposition, development, and removal of the photoresist layer. Here we demonstrate that metal thin films evaporated on glass can be directly patterned by a spatially modulated pulsed Nd-YAG laser beam (wavelength = 1064 nm, pulse width = 6 ns) incident from the backside of the substrate. This method utilizes a pulsed laser-induced thermo-elastic force exerted on the film which plays a role in detaching it from the substrate. High-fidelity patterns at the micrometer scale have been fabricated over a few square centimeters by a single pulse with pulse energy of 850 mJ. This is attributed to the fact that deposited metal films are polycrystalline with nano-sized grains, and thus localized etching of the material is possible with shearing along the weakly bonded grain boundary regions. We have also developed a nano-block model to simulate the laser-direct patterning of nanocrystalline thin films. Experimental results could be well described with this simulation model. The patterning process presented here provides a simple photoresist-free route to fabricate metal thin film patterns on transparent substrates.</P>
LES기반 연소모델과 Helmholtz 방정식을 이용한 LIMOUSINE 버너의 연소불안정 해석
신영준(Youngjun Shin),전상태(Sangtae Jeon),김용모(Yongmo Kim) 한국연소학회 2017 한국연소학회지 Vol.22 No.3
This study has numerically investigated the flame—acoustics interactions in the turbulent partially premixed flame field. In the present approach, in order to analyze the combustion instability, the present approach has employed the LES-based combustion model as well as the Helmholtz solver. Computations are made for the validation case of the partially premixed LIMOUSINE burner. In terms of the FFT data, numerical results are compared with experimental data. Moreover, Helmholtz equation in frequency domain is solved by combining CFD field data including the flight time from a nozzle to the flame zone. Based on numerical results, the detailed discussions are made for the essential features of the combustion instability encountered in the partially premixed burner.
이석준,오상태,신운섭 관동대학교 의과학연구소 2001 關東醫大學術誌 Vol.5 No.1
Angiogenesis, the process of new blood capillary formation, is an important component of a number of serious disease including cancer growth and metastasis, diabetic retinopathy, rheumatoid arthritis, and many others. Coronarin A, isolated from rhizomes of the Brazilian antirheumatic medicinal plant, and synthetic related compounds showed a significant cytotoxic effect against V-79 cell and sarcoma 180 ascites in Mice. In order to evaluate antiangiogenic effect of trans decaline type labdane compounds, 3, 4a, 5, 6 and 11 were synthesized from versatile chiral building blocks scalreol 1 and sclareolide 2 with appropriate synthetic methods. All tested materials have a mild growth inhibition effect on human endothelial cell line, ECV 304. We concluded that high antiangiogenic effect of coronarin A was caused by furan aromatic functional group on C-l2 position.
Park, Byong-Gon,Shin, Woon-Seob,Oh, Sangtae,Park, Gab-Man,Kim, Nam Ik,Lee, Seokjoon Elsevier 2017 Bioorganic & medicinal chemistry Vol.25 No.17
<P><B>Abstract</B></P> <P>We isolated the novel vasoactive marine natural products, (5<I>E</I>,10<I>E</I>)-14-hydroxy-2,6,10-trimethylpentadeca-5,10-dien-4-one (<B>4</B>) and sargachromenol D (<B>5</B>), from Sargassum siliquastrum collected from the coast of the East Sea in South Korea by using activity-guided HPLC purification. The compounds effectively dilated depolarization (50mMK<SUP>+</SUP>)-induced basilar artery contraction with EC<SUB>50</SUB> values of 3.52±0.42 and 1.62±0.63μM, respectively, but only sargachromenol D (<B>5</B>) showed a vasodilatory effect on endothelin-1 (ET-1)-induced basilar artery contraction (EC<SUB>50</SUB> =9.8±0.6μM). These results indicated that sargachromenol D (<B>5</B>) could act as a dual antagonist of <SMALL>L</SMALL>-type Ca<SUP>2+</SUP> channel and endothelin A/B<SUB>2</SUB> receptors. Moreover, sargachromenol D (<B>5</B>) lowered blood pressure in spontaneous hypertensive rats (SHRs) 2h after oral treatment at a dose of 80mg/kg dose and the effect was maintained for 24h. Based on our ex vivo and <I>in vivo</I> experiments, we propose that sargachromenol D (<B>5</B>) is a strong candidate for the treatment of hypertension that is not controlled by conventional drugs, in particular, severe-, type II diabetes-, salt-sensitive, and metabolic disease-induced hypertension.</P> <P><B>Graphical abstract</B></P> <P>Sargachromenol D (<B>5</B>) acts as a dual antagonist of L-type Ca<SUP>2+</SUP> channel and endothelin A/B<SUB>2</SUB> receptors.</P> <P>[DISPLAY OMISSION]</P>