1 GHz SRAM TESTER

Jun, Y. I.,Park, Hyung M.,Ma, D. S. 대한전자공학회 1989 ICVC : International Conference on VLSI and CAD Vol.1 No.1

A SRAM tester which has a maximum operating speed of 1 GHz is designed. The measurement timing accuracy of 60 psec is expected using a variable coaxial delay line which has a 10 psec delay time resolution. It prepares 22 input channels and 8 output channels.

Numerical Modeling of Transient Temperature and Stress in WC–10Co4Cr Coating During High-Speed Grinding

Jun Yi,Zhaohui Deng,Wei Zhou,Shujian Li 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.4

Based on the classical theory of heat conduction and thermoplastic mechanics, the three-dimensional heat transfer andthermal stress models of high-velocity oxygen fuel WC–10Co4Cr coating under the action of a moving heat source duringgrinding were developed. Considering temperature-dependent material properties, the transient temperature fi eld and thethermal stress fi eld generated in workpiece were simulated by a fi nite element method (FEM). As both the thermal conductivityand the specifi c heat capacity of WC–10Co4Cr are larger than 300 M, temperature rise mainly occurred in the coating. The rise in grinding temperature was discontinuous along the depth of the workpiece, and the temperature gradient at thecoating–substrate interface was found to be the largest. Due to the large diff erence in thermal expansion coeffi cient betweencoating and substrate material, considerable thermal stress was generated at the bonding surface. Grinding temperatureand thermal stresses at the coating–substrate interface started to increase with the decrease in coating thickness. Grindingsurface temperatures were measured experimentally for diff erent coating thicknesses, and simulation results were comparedwith the obtained experimental values. It was found that FEM results were well consistent with experimental observations.

Soil Freezing and Thawing Processes of Three Landscapes in the Middle Reaches of Heihe River Basin, China

Jun Yi,Mingan Shao,Ying Zhao 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

Effects of Cooling Rate on the Microstructure and Tensile Properties of Wire-Arc Additive Manufactured Ti–6Al–4V Alloy

Hui‑Jun Yi,Jin‑Woo Kim,Young‑Lak Kim,Sangyong Shin 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.8

Wire-arc additive manufacturing has emerged as a technology that could replace the conventional manufacturing processof titanium alloys. However, it produces a coarse β grain, which can accumulate via several deposited materials, resulting isstrong texture and anisotropy. To investigate potential solutions, the effects of the cooling rate on the resulting microstructureand tensile properties were studied. The cooling rate of the deposited materials was adjusted by interpass temperaturecontrol. Under rapid cooling, fine α + α′ grain with a low aspect ratio were observed and tensile and hardness propertieswere also improved.

Particle Filter Guided by Iterated Extended Kalman Filter

Junyi Zuo,Yingna Jia 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10

In particle filter (PF), the resampling step effectively solves the problem of particle degeneracy. However, it introduces the new problem of particle impoverishment. To tackle this problem, a PF Guided by the Iterated Extended Kalman filter (IEGPF) is proposed. Firstly, a maximum likelihood ratio (MLR) is defined to measure how well the particles, drawn from the transition prior density, match the likelihood model. Then, according to the MLR, particles are adaptively divided into two groups. Those in one group are drawn from the transition prior density, while those in the other group are drawn from the Gaussian approximate posterior density, obtained by the iterated extended Kalman filter (IEKF). Compared with traditional sampling strategies, the proposed strategy is more flexible for time-varying system characteristics, e.g., measurement noise variance. Simulation results demonstrate the improved performance of IEGPF over the Sampling Importance Resampling (SIR) PF, the Extended Kalman PF (EPF) and the Unscented Kalman PF (UPF), etc.

Development of a Virus Concentration Method and its Application for the Detection of Noroviruses in Drinking Water in China

Junyi Liu,Qingping Wu,Xiaoxia Kou 한국미생물학회 2007 The journal of microbiology Vol.45 No.1

A new procedure for the concentration of nonoviruses from water samples has been developed. This procedure (calcium flocculation-citrate dissolution method) uses the following steps: virus flocculation formed by treatment with 1 M CaCl2 and 1 M Na2HPO4, virus release by sodium citrate dissolution (0.3 M Na citrate, pH 3.5), and virus reconcentration by ultrafiltration. When reverse transcription (RT)-PCR was performed after the procedure, the overall detection sensitivity for seeded noroviruses in a one liter drinking water sample was as low as 1 RT-PCR unit, which is equal to a 10-6 dilution of the virus sample. This approach showed at least a 5-fold-higher sensitivity than the current method with its three steps of adsorption-elution-concentration. The newly developed procedure was used to test different brands of bottled drinking water from China for putative contamination with noroviruses. A total of 144 samples were analyzed; all of the samples were negative for norovirus specific nucleic acids.

Push-Out Tests on Interlocked Angles Connectors in Steel-Concrete-Steel Composite Structure

Junyi Chen,Yonghui Wang,Ximei Zhai,Xudong Zhi,Menghan Sun 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.2

This paper reported a new interlocked angle connector (IAC) for steel-concrete-steel sandwich structures. Shear performances of IACs embedded in normal concrete were studied via a push-out testing program, and the failure mode, shear resistance, and load–slip responses of IACs in normal concrete were obtained. The influences of height, width, thickness, orientation of steel angles, and interlocking bolts on shear behaviours of IACs were experimentally studied. The experimental results indicated that the ultimate shear resistances and slip capacities of IACs were improved via increasing the height, width and thickness of steel angles, while the orientation of steel angles exhibited limited influence on the ultimate shear resistances and failure modes of IACs. In addition, the analytical models were proposed for predicting ultimate shear resistances and load–slip behaviours of IACs. The experimental results were employed to validate the analytical models, and the proposed analytical models were found to provide more accurate predictions on ultimate shear resistances and load–slip behaviours of IACs as compared to the existing design codes.

Joint wireless and computational resource allocation for ultra-dense mobile-edge computing networks

( Junyi Liu ),( Hongbing Huang ),( Yijun Zhong ),( Jiale He ),( Tiancong Huang ),( Qian Xiao ),( Weiheng Jiang ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.7

In this paper, we study the joint radio and computational resource allocation in the ultra-dense mobile-edge computing networks. In which, the scenario which including both computation offloading and communication service is discussed. That is, some mobile users ask for computation offloading, while the others ask for communication with the minimum communication rate requirements. We formulate the problem as a joint channel assignment, power control and computational resource allocation to minimize the offloading cost of computing offloading, with the precondition that the transmission rate of communication nodes are satisfied. Since the formulated problem is a mixed-integer nonlinear programming (MINLP), which is NP-hard. By leveraging the particular mathematical structure of the problem, i.e., the computational resource allocation variable is independent with other variables in the objective function and constraints, and then the original problem is decomposed into a computational resource allocation subproblem and a joint channel assignment and power allocation subproblem. Since the former is a convex programming, the KKT (Karush-Kuhn-Tucker) conditions can be used to find the closed optimal solution. For the latter, which is still NP-hard, is further decomposed into two subproblems, i.e., the power allocation and the channel assignment, to optimize alternatively. Finally, two heuristic algorithms are proposed, i.e., the Co-channel Equal Power allocation algorithm (CEP) and the Enhanced CEP (ECEP) algorithm to obtain the suboptimal solutions. Numerical results are presented at last to verify the performance of the proposed algorithms.

Impact of Dietary Fiber Fermentation from Cereal Grains on Metabolite Production by the Fecal Microbiota from Normal Weight and Obese Individuals

Junyi Yang,Ali Keshavarzian,Devin J. Rose 한국식품영양과학회 2013 Journal of medicinal food Vol.16 No.9

Gut bacteria may influence obesity through the metabolites produced by dietary fiber fermentation (mainly,short-chain fatty acids [SCFA]). Five cereal grain samples (wheat, rye, maize [corn], rice, and oats) were subjected to in vitro digestion and fermentation using fecal samples from 10 obese and nine normal weight people. No significant differences in total SCFA production between the normal weight and obese groups were observed [279 (12) vs. 280 (12), mean (standard error), respectively; P = .935]. However, the obese microbiota resulted in elevated propionate production compared with that of normal weight [24.8(2.2) vs. 17.8(1.9), respectively; P = .008]. Rye appeared to be particularly beneficial among grain samples due to the lowest propionate production and highest butyrate production during fermentation. These data suggest that the dietary fibers from cereal grains affect bacterial metabolism differently in obese and normal weight classes and that certain grains may be particularly beneficial for promoting gut health in obese states.

MPC-based Two-stage Rolling Power Dispatch Approach for Wind-integrated Power System

Junyi Zhai,Ming Zhou,Shengxiao Dong,Gengyin Li,Jianwen Ren 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.2

Regarding the fact that wind power forecast accuracy is gradually improved as time is approaching, this paper proposes a two-stage rolling dispatch approach based on model predictive control (MPC), which contains an intra-day rolling optimal scheme and a real-time rolling base point tracing scheme. The scheduled output of the intra-day rolling scheme is set as the reference output, and the real-time rolling scheme is based on MPC which includes the leading rolling optimization and lagging feedback correction strategy. On the basis of the latest measured thermal unit output feedback, the closed-loop optimization is formed to correct the power deviation timely, making the unit output smoother, thus reducing the costs of power adjustment and promoting wind power accommodation. We adopt chance constraint to describe forecasts uncertainty. Then for reflecting the increasing prediction precision as well as the power dispatcher’s rising expected satisfaction degree with reliable system operation, we set the confidence level of reserve constraints at different timescales as the incremental vector. The expectation of up/down reserve shortage is proposed to assess the adequacy of the upward/downward reserve. The studies executed on the modified IEEE RTS system demonstrate the effectiveness of the proposed approach.