http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
High-electric-field Induced Trap Generation in AlGaN/GaN Heterostructure Field-effect Transistors
김형탁,LesterF. Eastman 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.2
A high-electric-field stress test was performed on AlGaN/GaN heterostructure field-effect transistors (HFETs) and degradations in the transistor characteristics were observed. The stress tests were combined with measurements of the low-frequency noise (Flicker's noise), the transient of the surface potential and the gate lag (dispersion between the pulsed and the static I-V characteristics) in order to investigate mechanisms for the observed degradation. Increases in the noise spectrum level, the magnitude of the transient of the surface potential, and the gate lag were observed after the HFETs had been submitted to the stress test. This result suggests that carrier traps are created in the devices under high field stress and that these traps aggravate the degradation of the device's DC and microwave power performances.
Thermal Conductivity of Al2O3/water Nanofluids
유대황,양호순,J. A. Eastman,K. S. Hong,T. E. Hong 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.II
Nanofluids, fluids with suspended nanoparticles, are of interest as a novel material for improving heat transfer efficiency. The conventional theory of two-component mixtures cannot explain the large enhancement of thermal conductivity of nanofluids. It is to be expected that the thermal conductivity of nanofluids is related with many factors, such as that effect of surfactants, dispersion of particles, convection or Brownian motion of nanoparticles, \emph{etc.} but the mechanism is not known. Thermal conductivity of Al$_{2}$O$_{3}$ nanofluids is studied in this work and compared with that of Fe nanofluids. To study the effect of pH of the base fluid on thermal conductivity, we measured the thermal conductivity of Al$_{2}$O$_{3}$ nanofluids with different pH values. Al$_{2}$O$_{3}$ nanoparticles were dispersed in water of pH values such as 7.0, 9.65 and 10.94. Nanoparticles have a tendency to form clusters, due to van der Waals interaction resulting in reduction of thermal conductivity. It is understood from the variation of thermal conductivity as the pH value of base fluids varies that the pH of base fluids affects clustering of nanoparticles.
Rules and validation processes for interoperable BIM data exchange
Yong-Cheol Lee,Charles M. Eastman,Wawan Solihin 한국CDE학회 2021 Journal of computational design and engineering Vol.8 No.1
Diverse industries have recognized the significance of a neutral data standard for seamless building information modeling (BIM) data exchanges and adopted commonly agreed schemes such as the industry foundation classes (IFC) schema for enhancing BIM data interoperability. To selectively employ domain-specific data exchange requirements, the AEC-FM (the Architecture, Engineering, Construction, and Facility Management) industries have developed their own schema with a subset of the IFC schema, named a model view definition (MVD). However, because of latent human errors, inadequate MVD definitions, and error-prone data mapping problems, the adoption of IFC for exchanging and sharing BIM data is frequently limited with severe data integrity issues. This challenging situation requires the detailed examination of the limitations of the heterogeneous IFC translation processes of the current BIM authoring and application tools. To accomplish this objective, the authors thoroughly investigated the two MVDs, the Coordination View Version 2.0 and the Construction Operations Building Information Exchange, broadly used as an international standard for developing the IFC translation processes, and then identified their intrinsic requirements/rules and developed rule-based data validation processes. These new intrinsic knowledge of the two MVD specifications will be fundamental foundations to create coherent BIM data exchange systems that are currently scattered and dispersed in heterogeneous IFC translation processes and structures. Newly revealed rules pertaining to these two MVDs have been executed with IfcDoc, which is the IFC documentation tool. This BIM data validation process is expected to not only accurately evaluate the translation processes between BIM native data and IFC ones but also help industry professionals ensure the integrity and the accuracy of their BIM data according to the BIM data exchange standards using the two MVDs. In addition, the outcomes of this research study are expected to bolster the interoperable BIM adoption and offer the values of greater consistency of BIM data exchange.
Floyd E. Hayes,Madeline E. Eastman,John C. Duncan 국립중앙과학관 2023 Journal of Asia-Pacific Biodiversity Vol.16 No.3
Many fish species are known to associate with echinoids. We studied the frequency of fishes associatingwith the diadematid Black Longspine Urchin Diadema setosum and Banded Sea Urchin Echinothrix cal amaris in the Phi Phi Islands of southwestern Thailand during July 17e20, 2022. A total of 1373 fishindividuals of 20 species associated with 1157 D. setosum, and 11 fish individuals of seven speciesassociated with 76 E. calamaris. The proportion of fish individuals per echinoid host was 8.2 times higherfor longer-spined D. setosum (1.19) than for E. calamaris (0.14), and the proportion of echinoids hostingone or more fish was 2.5 times higher for D. setosum (22.9%) than for E. calamaris (9.2%), supporting thehypothesis that fishes prefer to associate with echinoid species with the longest spines, which potentiallyprovide more protection against predators. All fishes associating with echinoids were small (<10 cm);most were adults, but for some species, all were juveniles. All fishes were facultative associates ofechinoids. Only three fish species had been previously reported associating with D. setosum and nonewith E. calamaris; the remaining fish species represent new records of association, including 17 forD. setosum and seven for E. calamaris.
Jung-Jae Kim,Chul-Young Jung,Jonathan G. Eastman,Hyoung-Keun Oh 대한정형외과학회 2016 Clinics in Orthopedic Surgery Vol.8 No.2
Background: Percutaneous iliosacral screw fixation can provide stable fixation with a minimally invasive surgical technique for unstable posterior pelvic ring injuries. This surgical technique is not limited by cases of difficult fracture patterns, sacral dysplasia, and small sacral pedicles that can occur in Asians. The purpose of this study was to investigate the incidence of the sacral dysplasia in the Korean population and determine the optimal direction of iliosacral screws by analyzing pelvic three-dimensional computed tomography (3D-CT) scans. Methods: One hundred adult patients who had pelvic 3D-CT scans were evaluated. The upper sacral morphology was classified into three groups, i.e., normal, transitional, and dysplastic groups; the cross-sectional area of the safe zone was measured in each group. S1 pedicle with a short width of more than 11 mm was defined as safe pedicle. The incidences of safe pedicles at different angles ranging from 0° to 15° were investigated in order to determine optimal angle for screw direction. Results: The incidence of normal, transitional, and dysplastic group was 46%, 32%, and 22%, respectively. There were significant increases of the cross-sectional area of the safe zones by increasing the angles from 0° to 15° in all groups. The incidence of safe pedicles increased similar to the changes in cross-sectional area. The overall incidence of safe pedicles was highest at the 10° tilt angle. Conclusions: The incidence of sacral dysplasia in Koreans was 54%, which is higher than previous studies for Western populations. The cross-sectional area of the safe zone can be increased by anteromedial direction of the iliosacral screw. Considering the diversity of sacral morphology present in the Korean population, a tilt angle of 10° may be the safest angle.
X-ray Irradiation Induced Reversible Resistance Change in Pt/TiO<sub>2</sub>/Pt Cells
Chang, Seo Hyoung,Kim, Jungho,Phatak, Charudatta,D’Aquila, Kenneth,Kim, Seong Keun,Kim, Jiyoon,Song, Seul Ji,Hwang, Cheol Seong,Eastman, Jeffrey A.,Freeland, John W.,Hong, Seungbum American Chemical Society 2014 ACS NANO Vol.8 No.2
<P>The interaction between X-rays and matter is an intriguing topic for both fundamental science and possible applications. In particular, synchrotron-based brilliant X-ray beams have been used as a powerful diagnostic tool to unveil nanoscale phenomena in functional materials. However, it has not been widely investigated how functional materials respond to the brilliant X-rays. Here, we report the X-ray-induced reversible resistance change in 40-nm-thick TiO<SUB>2</SUB> films sandwiched by Pt top and bottom electrodes, and propose the physical mechanism behind the emergent phenomenon. Our findings indicate that there exists a photovoltaic-like effect, which modulates the resistance reversibly by a few orders of magnitude, depending on the intensity of impinging X-rays. We found that this effect, combined with the X-ray irradiation induced phase transition confirmed by transmission electron microscopy, triggers a nonvolatile reversible resistance change. Understanding X-ray-controlled reversible resistance changes can provide possibilities to control initial resistance states of functional materials, which could be useful for future information and energy storage devices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2014/ancac3.2014.8.issue-2/nn405867p/production/images/medium/nn-2013-05867p_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn405867p'>ACS Electronic Supporting Info</A></P>
Wang, Yong-Hao,Wang, Songhu,Liu, Hui-Gen,Hinse, Tobias C.,Laughlin, Gregory,Wu, Dong-Hong,Zhang, Xiaojia,Zhou, Xu,Wu, Zhenyu,Zhou, Ji-Lin,Wittenmyer, R. A.,Eastman, Jason,Zhang, Hui,Hori, Yasunori,Nar American Astronomical Society 2017 The Astronomical journal Vol.154 No.2
<P>We present 10. R-band photometric observations of eight different transits of the hot Jupiter HAT-P-33b, which has been targeted by our Transiting Exoplanet Monitoring Project. The data were obtained by two telescopes at the Xinglong Station of National Astronomical Observatories of China (NAOC) from 2013 December through 2016 January, and exhibit photometric scatter of 1.6-3.0 mmag. After jointly analyzing the previously published photometric data, radial-velocity (RV) measurements, and our new light curves, we revisit the system parameters and orbital ephemeris for the HAT-P-33b system. Our results are consistent with the published values except for the planet to. star radius ratio (RP/R-*), the ingress/egress duration (tau) and the total duration (T-14), which together indicate a slightly shallower and shorter transit shape. Our results are based on more complete light curves, whereas the previously published work had only one complete transit light curve. No significant anomalies in Transit Timing Variations (TTVs) are found, and we place upper mass limits on potential perturbers, largely supplanting the loose constraints provided by the extant RV data. The TTV limits are stronger near mean-motion resonances, especially for the low-order commensurabilities. We can exclude the existence of a perturber with mass larger than 0.6, 0.3, 0.5, 0.5, and 0.3 M-circle plus near the 1: 3, 1: 2, 2: 3, 3: 2, and 2: 1 resonances, respectively.</P>