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排序方式: 共有89条查询结果,搜索用时 15 毫秒
1.
Minyoung Jeong Se Gyo Han Woong Sung Seunghyun Kim Jiwoo Min Mi Kyong Kim Wookjin Choi Hansol Lee Dongki Lee Min Kim Kilwon Cho 《Advanced functional materials》2023,33(27):2300695
A photomultiplication (PM)-type organic photodetector (OPD) that exploits the ionic motion in CsPbI3 perovskite quantum dots (QDs) is demonstrated. The device uses a QD monolayer as a PM-inducing interlayer and a donor–acceptor bulk heterojunction (BHJ) layer as a photoactive layer. When the device is illuminated, negative ions in the CsPbI3 QD migrate and accumulate near the interface between the QDs and the electrode; these processes induce hole injection from the electrode and yield the PM phenomenon with an external quantum efficiency (EQE) >2000% at a 3 V applied bias. It is confirmed that the ionic motion of the CsPbI3 QDs can induce a shift in the work function of the QD/electrode interface and that the dynamics of ionic motion determines the response speed of the device. The PM OPD showed a large EQE-bandwidth product >106 Hz with a −3 dB frequency of 125 kHz at 3 V, which is one of the highest response speeds reported for a PM OPD. The PM-inducing strategy that exploits ionic motion of the interlayer is a potential approach to achieving high-efficiency PM OPDs. 相似文献
2.
Silver Nanoflower Decorated Graphene Oxide Sponges for Highly Sensitive Variable Stiffness Stress Sensors 下载免费PDF全文
Fakhre Alam Khan C. Muhammed Ajmal Seonghyun Bae Sungwon Seo Hyungpil Moon Seunghyun Baik 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(24)
Soft conductive materials should enable large deformation while keeping high electrical conductivity and elasticity. The graphene oxide (GO)‐based sponge is a potential candidate to endow large deformation. However, it typically exhibits low conductivity and elasticity. Here, the highly conductive and elastic sponge composed of GO, flower‐shaped silver nanoparticles (AgNFs), and polyimide (GO‐AgNF‐PI sponge) are demonstrated. The average pore size and porosity are 114 µm and 94.7%, respectively. Ag NFs have thin petals (8–20 nm) protruding out of the surface of a spherical bud (300–350 nm) significantly enhancing the specific surface area (2.83 m2 g?1). The electrical conductivity (0.306 S m?1 at 0% strain) of the GO‐AgNF‐PI sponge is increased by more than an order of magnitude with the addition of Ag NFs. A nearly perfect elasticity is obtained over a wide compressive strain range (0–90%). The strain‐dependent, nonlinear variation of Young's modulus of the sponge provides a unique opportunity as a variable stiffness stress sensor that operates over a wide stress range (0–10 kPa) with a high maximum sensitivity (0.572 kPa?1). It allows grasping of a soft rose and a hard bottle, with the minimal object deformation, when attached on the finger of a robot gripper. 相似文献
3.
Softsensors or virtual sensors are key technologies in industry because important variables such as product quality are not always measured on-line. In the present work, two-stage subspace identification (SSID) is proposed to develop highly accurate softsensors that can take into account the influence of unmeasured disturbances on estimated key variables explicitly. The proposed two-stage SSID method can estimate unmeasured disturbances without the assumptions that the conventional Kalman filtering technique must make. Therefore, it can outperform the Kalman filtering technique when innovations are not Gaussian white noises or the characteristics of disturbances do not stay constant with time. The superiority of the proposed method over the conventional methods is demonstrated through numerical examples and application to an industrial ethylene fractionator. 相似文献
4.
Lee Wang-Hee Oh Il-Nam Choi Seunghyun Park Jong-Tae 《Food science and biotechnology》2021,30(10):1313-1319
Food Science and Biotechnology - Food authenticity is one of the largest concerns in recent days. As kimchi has been a global food, its production origin has been important issue, particularly due... 相似文献
5.
Determination of twisting angle of electrospun nanofiber bundle for continuous electrospinning system 下载免费PDF全文
Electrospinning continuously produced twisted nanofibers with a convergence coil and a rotating ring collector. The positively charged nozzle was used in the electrospinning process to deposit electrospun fibers of polyacrylonitrile onto a rotating ring collector. By withdrawing the electrospun fibers from the rotating ring collector, it was possible to spin the electrospun fibers yarn. In this study, theoretical approaches and numerical simulations were used to determine the twisting angle of the yarn. Using the equations developed in this study, we performed numerical simulations and compared the experimental results with the numerical simulation results. Mechanical properties of the fiber bundle were analyzed for twisting angle. It was confirmed the relationship among the winding drum, the ring collector, and flux of the fibers mass per time during electrospinning in the developed system. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45528. 相似文献
6.
Han-Jun Oh In-Ki Kim Kyung-Wook Jang Jong-Ho Lee Seunghyun Lee Choong-Soo Chi 《Metals and Materials International》2012,18(4):673-677
The effects of electrolyte and applied potentials on TiO2 nanotube morphologies were investigated. The specific surface area of the TiO2 nanotubes was measured to be 57 m2/g for titania nanotubes formed in HF, and 147 m2/g formed in organic electrolyte, respectively. The results of adsorption-desorption isotherms agree with the morphology of TiO2 nanotubes. The length and average diameter of nanotubes were influenced by electrolyte and anodic potentials. The multilayered TiO2 nanotube arrays can be fabricated by changing the electrolyte composition during anodization. 相似文献
7.
Dongsoo?KimEmail author Seunghyun?Lim Gunhee?Han 《Analog Integrated Circuits and Signal Processing》2005,45(2):131-141
The eye tracker is a system that detects the point where the user gazes on. The conventional eye tracker using a Charge-Coupled
Device (CCD) camera needs many peripherals and software computation causing high cost, computation time and power consumption.
This paper proposes a single-chip eye tracker using smart CMOS Image Sensor (CIS) pixels. The proposed eye tracker does not
require additional peripherals and operates at higher speed than the conventional approach. The prototype chip was designed
and fabricated for a 32 × 32 smart CIS pixels array with a 0.35-μ m CMOS process. The test results show ± 1 pixel error at
the rate of 125 frame-per-second. The power consumption is 260 mW with 3.3 V supply voltage and the silicon area is 3.8 mm2 相似文献
8.
M. Shamsuzzoha Seunghyun Lee Moonyong Lee 《Korean Journal of Chemical Engineering》2009,26(3):622-630
An analytical method for the design of a proportional-integral-derivative (PID) controller cascaded with a second-order lead-lag
filter is proposed for various types of time-delay process. The proposed design method is based on the IMC-PID method to obtain
a desired, closed-loop response. The process dead time is approximated by using the appropriate Pade expansion to convert
the ideal feedback controller to the proposed PID·filter structure with little loss of accuracy. The resulting PID·filter
controller efficiently compensates for the dominant process poles and zeros and significantly improves the closed-loop performance.
The simulation results demonstrate the superior performance of the proposed PID·filter controller over the conventional PID
controllers. A guideline for the closed-loop time constant, λ, is also suggested for the FOPDT and SOPDT models. 相似文献
9.
Seunghyun Cho Tae-Eun Chang Hyung-Pil Park GyunMyoung Park 《Microelectronics Reliability》2010,50(2):242-250
Printed Circuit Board (PCB) warpage increases as thickness decreases and ultimately is attributed to CTE mismatch and thickness geometry of the components. Recently, a thin Ball Grid Array (BGA) PCB has been developed due to the advantages like high electrical translation speed with low signal noise. Large warpage severely limited by BGA PCB performance leads to reliability issues modes such as crack and delamination between interconnection components. This is why a dummy design on a BGA PCB and metal stiffener on a Flip Chip (FC) BGA PCB warpage are analyzed experimentally.At the first step, new dummy design in BGA PCB (BoC type) is proposed to reduce warpage. The new dummy design is shaped as a bar. Results of the statistical experimental analysis show PCB warpage using the new dummy design is significantly reduced compared to the use of a PCB with a conventional dummy design. Furthermore, the new dummy design decreases PCB warpage by about 67%. These results signify that the stiffness of the BoC PCB is improved by the new dummy design because the bar-shaped Cu pattern in the dummy acts as a rigid bar stiffener.At the second step, metal stiffener effect is studied to reduce coreless FCBGA PCB warpage. Coreless FCBGA PCB, coreless FCBGA package, and specimens with non-symmetric structure are considered to determine metal stiffener effect on warpage. The experimental results show that metal stiffener has high stiffness, and it seems very effective on reducing average and standard deviation of coreless PCB warpage. 相似文献
10.
Earthquake strong motion recordings from 29 sites with instrumented structures and free-field accelerographs are used to evaluate variations between foundation-level and free-field ground motions. The focus of the paper is on buildings with surface and shallowly embedded foundations. The foundation/free-field ground motion variations are quantified in terms of frequency-dependent transmissibility function amplitude ∣H∣. Procedures are developed to fit to ∣H∣ analytical models for base slab averaging for the assumed conditions of a rigid base slab and a vertically propagating, incoherent incident wave field characterized by ground motion incoherence parameter κ. The limiting assumptions of the model are not strictly satisfied for actual structures, and the results of the identification are apparent κ values (denoted κa) that reflect not only incoherence effects, but also possible foundation flexibility and wave inclination effects. Nonetheless, a good correlation is found between κa values and soil shear wave velocity for sites with stiff foundation systems. Based on these results, recommendations are made for modifying free-field ground motions to estimate base slab motions for use in response analyses of buildings. 相似文献