Two-Step Reset in the Resistance Switching of the Al/TiO_<i>x</i>/Cu Structure

Shao, Xing L.,Zhao, Jin S.,Zhang, Kai L.,Chen, Ran,Sun, Kuo,Chen, Chang J.,Liu, Kai,Zhou, Li W.,Wang, Jian Y.,Ma, Chen M.,Yoon, Kyung J.,Hwang, Cheol S. American Chemical Society 2013 ACS APPLIED MATERIALS & INTERFACES Vol.5 No.21

<P>Two-step reset behaviors in the resistance switching properties of the top Al/TiO<SUB><I>x</I></SUB>/bottom Cu structure were studied. During the electroforming and set steps, two types of conducting filaments composed of Cu and oxygen vacancies (Cu-CF and V<SUB>O</SUB>-CF) were simultaneously (or sequentially) formed when Al was negatively biased. In the subsequent reset step with the opposite bias polarity, the Cu-CFs ruptured first at ∼0.5 V, and formed an intermediate state. The trap-filled V<SUB>O</SUB>-CFs were transformed into a trap-empty state, resulting in a high-resistance state at ∼1 V. Matrix phase in the electrochemical metallization cell can play an active role in resistance switching.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2013/aamick.2013.5.issue-21/am403498q/production/images/medium/am-2013-03498q_0007.gif'></P>

Fluorescent Realgar Quantum Dots: New Life for an Old Drug

J. Z. Wu,G. Chen,Y. B. Shao,J. Liu,Y. C. Sun,H. S. Lin,Paul C. Ho 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.1

"Quantum dots (QDs) possess unique properties that are expected for various applications. Herein, realgar (As4S4) QDs were synthesized via a wet chemical method in a coordinating solvent (e.g., ethanolamine (EA)) with assistance of an acid (e.g., citric acid (CA)). The asprepared realgar QDs using EA and CA have a narrow size distribution with a mean value of 5.48 nm and a relative standard deviation of 20%, and exhibit bright photoluminescence (PL) in a short wavelength window (< 480 nm) with high quantum yield up to 70%. Moreover, realgar QDs can retain their high PL after one-year storage, indicating their excellent stability. Bulk realgar is a commonly used traditional medicine, however, its water-insolubility limits its broad applications. Realgar QDs could be an alternative for the bulk realgar owing to their excellent water-solubility and efficient PL. In preliminary in vivo toxic and pharmaceutical experiments, the synthesized realgar QDs at a single oral dose of 10.0 mg realgar/kg body weight for 21 days showed tolerability in healthy mice and effective against tumor-bearing nude mice, respectively. In this study, assembly of realgar QDs into specific hollow nanospheres was first constructed by introducing an acid into their original colloidal solution. Simple dissolution of such assemblies in EA can partially return them into the fluorescent QDs. Such property is desired for a variety of media-responsive luminescence materials. In addition, a flexible inorganic/organic hybrid composite film was fabricated for the first time by incorporation of realgar QDs into polyvinyl alcohol matrix. The resulting film presents excellent PL, good transparency, intense mechanical strength and facile processibility, which meet the requirements for device integration. "

Residual static strength of cracked concrete-filled circular steel tubular (CFCST) T-joint

M.J. Cui,Y.B. Shao 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.4

Concrete-filled circular t steel tubular joints (CFSTJs) in practice are frequently subjected to fluctuated loadings caused by wind, earthquake and so on. As fatigue crack is sensitive to such cyclic loadings, assessment on performance of CFSTJs with crack-like defect attracts more concerns because both high stress concentration at the brace/chord intersection and welding residual stresses along weld toe cause the materials in the region around the intersection to be more brittle. Once crack initiates and propagates along the weld toe, tri-axial stresses in high gradient around the crack front exist, which may bring brittle fracture failure. Additionally, the stiffness and the load carrying capacity of the CFSTJs with crack may decrease due to the weakened connection at the intersection. To study the behaviour of CFSTJs with initial crack, experimental tests have been carried out on three full-scale CFCST T-joints with same configuration. The three specimens include one uncracked joint and two corresponding cracked joints. Load-displacement and load-deformation curves, failure mode and crack propagation are obtained from the experiment measurement. According to the experimental results, it can be found that he load carrying capacity of the cracked joints is decreased by more than 10% compared with the uncracked joint. The effect of crack depth on the load carrying capacity of CFCST T-joints seems to be slight. The failure mode of the cracked CFCST T-joints represents as plastic yielding rather than brittle fracture through experimental observation.

AN ENERGY ANALYSIS ON GRAIN DRYING SYSTEMS IN CHINA

Y . J . Shao 한국농업기계학회 1993 ICAMPE 요약집 Vol.3 No.-

Flexible Optical Waveguides for Uniform Periscleral Cross-Linking

Kwok, Sheldon J. J.,Kim, Moonseok,Lin, Harvey H.,Seiler, Theo G.,Beck, Eric,Shao, Peng,Kochevar, Irene E.,Seiler, Theo,Yun, Seok-Hyun The Association for Research in Vision and Ophthal 2017 Investigative ophthalmology & visual science Vol.58 No.5

<P><B>Purpose</B></P><P>Scleral cross-linking (SXL) with a photosensitizer and light is a potential strategy to mechanically reinforce the sclera and prevent progressive axial elongation responsible for severe myopia. Current approaches for light delivery to the sclera are cumbersome, do not provide uniform illumination, and only treat a limited area of sclera. To overcome these challenges, we developed flexible optical waveguides optimized for efficient, homogeneous light delivery.</P><P><B>Methods</B></P><P>Waveguides were fabricated from polydimethylsiloxane elastomer. Blue light (445 nm) is coupled into the waveguide with an input fiber. Light delivery efficiency from the waveguide to scleral tissue was measured and fit to a theoretical model. SXL was performed on fresh porcine eyes stained with 0.5% riboflavin, using irradiances of 0, 25, and 50 mW/cm<SUP>2</SUP> around the entire equator of the eye. Stiffness of scleral strips was characterized with tensiometry.</P><P><B>Results</B></P><P>Light delivery with a waveguide of tapered thickness (1.4–0.5 mm) enhanced the uniformity of light delivery, compared to a flat waveguide, achieving a coefficient of variation of less than 10%. At 8% strain, sclera cross-linked with the waveguides at 50 mW/cm<SUP>2</SUP> for 30 minutes had a Young's modulus of 10.7 ± 1.0 MPa, compared to 5.9 ± 0.5 MPa for no irradiation, with no difference in stiffness between proximally and distally treated halves. The stiffness of waveguide-irradiated samples did not differ from direct irradiation at the same irradiance.</P><P><B>Conclusions</B></P><P>We developed flexible waveguides for periscleral cross-linking. We demonstrated efficient and uniform stiffening of a 5-mm-wide equatorial band of scleral tissue.</P>

Strain Engineered Quantum Dots in a Well (DWELL) Photodetectors and Resonant Tunneling Filters in DWELL Photodetectors

Ajit V. Barve,J. Shao,Y. Sharma,R. Shenoi,J. O. Kim,S. J. Lee,S. K. Noh,Sanjay Krishna 한국진공학회 2009 한국진공학회 학술발표회초록집 Vol.37 No.-

Low temperature magneto-transport properties in bilayered magnetic anti-dot mircoarrays

Deshpande, N.G.,Hwang, J.S.,Seo, M.S.,Yoo, Y.J.,Rhee, J.Y.,Kim, K.W.,Shao, Y.C.,Chen, K.H.,Pong, W.F.,Lee, Y.P. New York] ; North-Holland 2014 APPLIED SURFACE SCIENCE - Vol.314 No.-

Magneto-transport study on the photolithographically-patterned anti-dot micro-arrays of cobalt upper-layer over a uniform thin nickel under-layer has been carried out. Circular anti-dots in rhomboidal symmetry were fabricated. The magnetoresistance (MR) curves were recorded for magnetically-easy and -hard axes of the bilayer structure at various temperatures. In addition to anisotropic MR, at low temperatures, the MR data shows anomalous behavior with several kinks and plateau regions, indicating complex reversal phenomena. Further, decrease in temperature results in increase of MR average peak height, double splitting of MR peaks and broadening of MR peaks. Additionally, the exchange bias behavior was found in the transverse MR curve; while no significant exchange effect was seen in the longitudinal MR curve. Using energy dispersive spectrum and X-ray absorption spectra taken at Co L<SUB>3,2</SUB>-edge, the presence of CoO layer over the bilayer structure was detected; while the Ni under-layer remained deoxidized.

한우 거세우의 계절 및 군 두수별 행동 특성

하재정,이용준,조재희,장원진,김연욱,송영한,Ha, J.J.,Rhee, Y.J.,Cho, J.H.,Jang, W.J.,Kim, Y.W.,Li, Shao-Gang,Song, Y.H. 한국축산환경학회 2008 축산시설환경학회지 Vol.14 No.1

본 시험은 두당 동일한 면적에서 비육전기 한우 거세우의 계절별 개체유지 및 사회적 행동 특성을 구명하고자 실시하였다. 15개월령의 한우 거세우 48두를 공시하여 두당 사육면적은 동일한 상태에서 각각 4두, 8두, 12두씩 2반복으로 시험을 수행하였으며, 행동측정은 15개월령, 17개월령, 19개월령에 분석하였으며, 그 결과를 요약하면 다음과 같다. 1. 섭식행동(FD) 중 섭취시간은 가을철에 가장 높게 나타났으며, 여름철이 가을, 겨울철 보다 유의적으로 짧은 섭취시간을 나타냈다(p<0.05). 2. 기립행동(ST)은 여름철이 유의적으로 가장 짧은 시간을 보였다(p<0.05). 3. 횡와행동(LD)은 여름철이 가을, 겨울철보다 유의적인 증가를 나타냈다(p<0.05). 4. 음수행동(DR)에서는 겨울철에 유의적으로 감소하였다(p<0.05). 5. 개체유지 행동 중 함기행동(SG)과 긁기행동(SR)은 여름철보다 겨울철에 유의적인 증가를 보였다(p<0.05). 6. 사육공간별 행동 특성에서는 마리당 평균시간에서 걷기행동(WA)이 군 두수가 가장 큰 그룹에서 유의적(p<0.05)으로 증가하였으며, 마리당 평균빈도에서는 군 두수가 가장 작은 그룹에서 자기몸핥기(SG)가 유의적(p<0.05)으로 증가하였다. 이상의 결과를 토대로 계절 및 군 두수별로 한우 거세우의 행동 특성이 각각 다른 것으로 나타났고, 향후 보다 더 많은 개체수를 대상으로 다양한 시험조건 하에서 시험을 수행한다면 시설 및 환경을 연계해 친환경 축사조건을 구명할 수 있을 것으로 판단된다. This study was carried out to determine the behavioral characteristics on season and group size of Hanwoo steer. Forty eight Hanwoo steers were video-recorded at 15, 17 and 19 months of age for behavioral measurement. Space allowance was kept consistence with either group. The results showed that eating behavior of Hanwoo steers was strongly influenced (p<0.05) during seasonal transition, being the lowest in summer and the highest in autumn. With seasonal transition, standing time would linearly increase (p<0.05). In summer, steers spent more (p<0.05) time tying down but relatively less (p<0.05) time walking and fighting, meanwhile they much less (p<0.05) scratching and rubbing. In autumn, steers showed more grooming behavior (p<0.05) contrasted to the other seasons. Steers spent more (p<0.05) walking time when raised in large group and increased (p<0.05) grooming frequency when raised in small group.

A study of the transition between the non-polar and bipolar resistance switching mechanisms in the TiN/TiO2/Al memory

Shao, X.,Kim, K.,Yoon, K.,Song, S.,Yoon, J.,Kim, H.,Park, T.,Kwon, D.,Kwon, Y.,Kim, Y. Royal Society of Chemistry 2016 Nanoscale Vol.8 No.36

<P>Thermochemical and electronic trapping/detrapping mechanism-based resistance switching in TiO2 is one of the most extensively researched topics in the field of resistance-switching random access memory (ReRAM). In this study, the subtle correlation between the formation and rupture of the Magneli-based conducting filament (CF), which is the mechanism of non-polar thermochemical-reaction-based switching, and the electron trapping/detrapping at the defect centers, which is the mechanism of bipolar electronic switching, is examined in detail. The chemical interaction between the TiN top electrode and the TiO2 layer generates a stable and immobile electron trapping layer, which is called a 'switching layer', whereas the thin region between the just-mentioned switching layer and the remaining Magneli CF after the thermochemical reset comprises a non-switching layer. The seemingly very complicated switching behavior with respect to the bias polarity, compliance current, and detailed biasing sequence could be reasonably explained by the phenomenological model based on the combined motions of the CF, switching layer, and non-switching layer. Light-induced detrapping experiments further supplement the suggested switching model.</P>

The current limit and self-rectification functionalities in the TiO2/HfO2 resistive switching material system

Yoon, J.,Kwon, D.,Kim, Y.,Kwon, Y.,Yoon, K.,Park, T.,Shao, X.,Hwang, C. Royal Society of Chemistry 2017 Nanoscale Vol.9 No.33