982 research outputs found
Design and testing of fiber-constrained electroactive polymer
No full textSoft robotics take advantage of active materials to regenerate many complex motions, including low-force functions, such as camouflage, micro-grabbing, or agile locomotion of micro robot. For these applications, traditional actuators, like electric motors and combustion engines, are unnecessarily large and heavy. In contrast, electro-active polymers (EAP) such as electrostatically actuated dielectric elastomers (DE) are considered very suitable technologies for these applications. In particular, owing to their simplicity, high strain and energy densities, and low noise, DE’s are currently the most promising candidates for small scale biomimetic applications. In this study, new fiber-constrained DE designs are developed, in order to obtain controlled uniaxial actuation that suits soft robotics and small scale actuation. Also, micro-wrinkle instabilities that occur in fiber-constrained membranes are examined. The property of wrinkle defers by controlling the geometrical parameters and the amount of strain in a membrane. Therefore controlling the shape of wrinkle is applicable for micro-actuation. In addition, image analysis methodology is discussed and creative ways of analyzing the image data is established.Submission published under a 24 month embargo labeled 'U of I only', the embargo will last until 2017-05-01The student, Kun Hyuck Lee, accepted the attached license on 2015-05-01 at 05:23.The student, Kun Hyuck Lee, submitted this Thesis for approval on 2015-05-01 at 06:12.This Thesis was approved for publication on 2015-05-01 at 15:48.DSpace SAF Submission Ingestion Package generated from Vireo submission #8220 on 2015-07-22 at 14:19:10Made available in DSpace on 2015-07-22T22:34:04Z (GMT). No. of bitstreams: 2
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Previous issue date: 2015-05-01Embargo set by: Seth Robbins for item 79935
Lift date: 2017-07-22T22:34:16Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 79935 on 2017-07-23T09:15:19Z
Linear scaling relationship of N\'{e}el temperature and dominant magnons in pyrochlore ruthenates
No full textWe present a systematic Raman spectroscopy study on a series of pyrochlore
ruthenates, a system which is not yet clearly settled on its magnetic origin
and structure. Apart from the Raman-active phonon modes, new peaks that appear
in the energy range of 15 - 35 meV below the N\'{e}el temperature are assigned
as one-magnon modes. The temperature evolution of one-magnon modes displays no
significant thermal dependence in mode frequencies while the intensities
decrease monotonically. Remarkably, one-magnons from all compounds show similar
characteristics with a single dominant peak at lower energy and weaker side
peaks at a couple of meV higher energy. Most importantly, we uncover a striking
proportionality between the dominant magnon mode energies and the N\'{e}el
temperature values. Our results suggest the Ru ions may have similar or the
same magnetic phase in all pyrochlore ruthenates of our study. We have thus
found an avenue for directly tuning the magnetic exchange interaction by the
selection of the -site ion
Sharp contrast in the electrical and optical properties of vanadium Wadsley (VmO2m+1, m > 1) epitaxial films selectively stabilized on (111)-oriented Y-stabilized ZrO2
No full textFour oxidation states (V2+, V3+, V4+, and V5+) in vanadium oxides and the conversion between them have attracted attention for application to batteries and electronics. Compared to single-valence counterparts, however, there have been few reports on the fundamental properties of mixed-valence vanadium oxide films, as their complexity and closeness in thermodynamic phase diagrams hinder the formation of pure phases in film. Here, using an epitaxial growth technique with precise control of oxygen partial pressure (20-100 mTorr) on (111)-oriented Y-stabilized ZrO2, we selectively stabilize pure phases of VO2(B) (m = infinity), V6O13 (m = 6), and V2O5 (m = 2), so-called Wadsley phases (VmO2m+1, m > 1) in which V4+ and/or V5+ can coexist. Fractional increase of V4+ changes the electrical ground state, insulating VO2 (B) and V2O5, metallic V6O13 transition into insulators below 150 K. While VO2 (B) and V(6)O(13 )exhibit strong spectral weights at low photon energy in the room-temperature extinction coefficients, the band-edge absorption shifts toward higher photon energy for smaller m, opening an indirect band gap of 2.6 eV in V2O5 . The sharp contrast of electrical and optical properties between vanadium Wadsley phases highlights the importance of precisely controlling the oxidation state of vanadium. ©2019 American Physical Societ
A Novel Distributed Translator for an ATSC Terrestrial DTV System
No full textThis paper presents a new design and implementation method of distributed translator (DTxR), termed the equalization DTxR (EDTxR), for distributed translator network in ATSC systems. EDTxR has a simple structure and does not require any devices to be added to studio or transmitter facilities already deployed. EDTxRs which retransmit the same transmitter signal can have identical output symbol streams among them without additional synchronization information by utilizing the structure of the equalization digital on-channel repeater (EDOCR). Moreover, they can synchronize output frequency among them without global positioning system (GPS) clock receivers by adopting a crystal oscillator for each translator and compensating the frequency offset of the each crystal oscillator through the carrier and timing recovery. To verify the proposed method, multiple EDTxRs are implemented and tested in the laboratory and in the field. Through the tests, it is confirmed that EDTxR is a simple and economic distributed translator for distributed transmission system which does not need additional synchronization devices. Therefore, EDTxR can be a promising translator for coverage extension of digital terrestrial television broadcasting under spectrum deficient situations
An efficient transmission of traffic and traveler information using digital multimedia broadcasting network
No full textThis paper introduces an efficient transmission of traffic and traveler information through digital multimedia broadcasting system, which is a multimedia and mobility empowered version of European digital audio broadcasting system. By introducing Korean characteristic traffic information into the transport protocol expert group messages, we could get highly efficient traffic and traveler information system that could be used in Korea as well as in European countries
Clinical outcomes of radical radiotherapy for pulmonary sarcomatoid carcinoma
No full textPurpose: Pulmonary sarcomatoid carcinoma (PSC) is recognized for its aggressiveness and poor prognosis. The role of radical radiotherapy in PSC remains uncertain due to its scarcity and limited data. In the absence of an effective systemic agent, this study aims to explore the possibility of cure and to investigate potential prognostic factors and treatment outcomes. Materials and Methods: From January 2005 to December 2021, 149 PSC patients were identified. Among 62 patients who received radiotherapy for lung lesions, 25 who underwent palliative radiotherapy and 16 who underwent surgery were excluded. Results: The median patient age was 71 years. The majority were male, and 17 patients (81.0%) were diagnosed at an advanced stage. After radical radiotherapy, distant metastasis (47.6%) was the most common site of failure, while the local recurrence rate was quite low (9.5%). Eventually, five patients (26.3%) demonstrated either a partial response or complete remission, including three complete re-missions with durable responses. The median progression-free survival (PFS) and overall survival were 4.6 months and 7.9 months, respectively. Univariate and multivariate analyses revealed that a tumor size >5 cm was associated with a worse prognosis (p = 0.045), while a radiation dose >58 GyEQD2 was significantly associated with better PFS (p = 0.038). Conclusion: This study demonstrates clinical outcomes after radical radiotherapy in managing PSC, suggesting tumor size and radiation dose could be a predictor of a systemic response. Given the known bad prognosis but complete remission could be achieved in certain subgroups, future research should explore the potential strategies using radical radiotherapy for this challenging patient population.Y
Moduation and pre-equalization method to minimize time delay in Equalization Digital On-Channel Repeater
No full textThis paper presents novel modulation and pre-equalization methods to minimize a signal processing time delay in the Equalization Digital On-Channel Repeater (EDOCR) for the ATSC terrestrial digital TV system. The proposed modulation method uses Equi-Ripple (ER) filter for Vestigial Side Bands (VSB) pulse shaping instead of conventional Square Root Raised Cosine (SRRC) filter. And the proposed pre-equalization method calculates pre-equalizer filter coefficients by comparing a base-band signal as a reference signal and a demodulated repeater output signal, and then creates new VSB pulse shaping filter coefficients by the convolution of the ER filter and the pre-equalizer filter coefficients. The new VSB pulse shaping filter minimizes the time delay of EDOCR by adjusting the number of its pre-taps and also compensates the linear distortions due to the use of the ER filter and mask filter
Electrical and Optical Properties of VO2 Polymorphic Films Grown Epitaxially on Y-Stabilized ZrO2
No full textVanadium dioxide (VO2) polymorphs have many interesting physical and chemical properties that are crystal-structure dependent. It is reported that polymorphic (010) VO2(M1), (100) VO2(A), and (100) VO2(B) can be epitaxially grown on (001)-, (011)-, and (111)-oriented Y-stabilized ZrO2 (YSZ), respectively. While VO2(M1) shows a typical metal-insulator transition near 68 degrees C, and VO2(B) exhibits insulating behavior, the resistivity of VO2(A) is lower by three orders of magnitude than that of (100) VO2(A) epitaxial films previously grown on (011) SrTiO3. Ellipsometry reveals that the bandgap of VO2(A) also decreases. Each VO2 polymorphic film grown on cost-effective YSZ will be of great interest for numerous electronic and energy applications © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei
MIMO 채널 사운딩 시스템에서 송신 안테나 멀티플렉싱에 관한 새로운 구조 제안
No full text학위논문(석사) - 한국정보통신대학교 : 공학부, 2008.2, [ vii, 48 p. ]It is anticipated that MIMO systems will play an important role in increasing spectrum efficiency and link reliability in the next generation wireless communication systems. As researches about MIMO systems are going on at a good pace, the need for studying MIMO radio channel has also been increased largely. Because MIMO wireless channel has spatially directional property unlike SISO channel, accurate field measurement of MIMO channel is required for analyzing MIMO channel and evaluating MIMO communication systems.
A conventional channel sounder for measuring MIMO radio channel is based on time division multiplexing (TDM) using pseudo noise (PN) sequence as a pilot sequence and can measure the MIMO channel accurately in slow fading environment. However this sounder has a big drawback that the accuracy of channel measurement is degraded largely in fast fading environment. To overcome this limitation, channel sounding architecture based on code division multiplexing (CDM) has already proposed, but the sequences for a sounding code was not presented until now.
In this thesis, we propose three different sequences with a very lowcorrelation property for CDM based MIMO channel sounder: Loosely Synchronous (LS) code, Kasami, and Chaotic sequences. To demonstrate the validity of each code, we experimented through computer simulations, and we concluded that LS code is the most suitable as a sounding code for CDM architecture. And for the case that CDM architecture represents some limitation of measurements because of large interferences according to the increase of transmitting sequences, we proposed CDM-TDM Hybrid architecture. From the analysis through simulation, we can find that the Hybrid architecture outperforms CDM and TDM in all different channel variation environments. Finally, we can conclude that LS code is the most appropriate code for CDM architecture and in situation where LS code represents bad performance with CDM architecture, MIMO channel measureme...한국정보통신대학교 : 공학부
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