• Current Optics and Photonics
• /
• v.1 no.3
• /
• pp.239-246
• /
• 2017

A compact plasmonic switching scheme, based on the phase change of a thin-film chalcogenide material ($Ge_2Sb_2Te_5$), is proposed and numerically investigated at optical-communication wavelengths. Surface plasmon polariton modal analysis is conducted for various thicknesses of dielectric and phase-change material layers, and the optimized condition is induced by finding the region of interest that shows a high extinction ratio of surface plasmon polariton modes before and after the phase transition. Full electromagnetic simulations show that multiple reflections inside the active region may conditionally increase the overall efficiency of the on/off ratio at a specific length of the active region. However, it is shown that the optimized geometrical condition, which shows generally large on/off ratio for any length of active region, can be distinguished by observing the multiple-reflection characteristic inside the active region. The proposed scheme shows an on/off switching ratio greater than 30 dB for a length of a few micrometers, which can be potentially applied to integrated active plasmonic systems.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.7
• /
• pp.3413-3430
• /
• 2017

With the fast increasing popularity of mobile services, ubiquitous mobile devices with enhanced sensing capabilities collect and share local information towards a common goal. The recent Mobile Crowd Sensing (MCS) paradigm enables a broad range of mobile applications and undoubtedly revolutionizes many sectors of our life. A critical challenge for the MCS paradigm is to induce mobile devices to be workers providing sensing services. In this study, we examine the problem of sensing task assignment to maximize the overall performance in MCS system while ensuring reciprocal advantages among mobile devices. Based on the overlapping coalition game model, we propose a novel workload determination scheme for each individual device. The proposed scheme can effectively decompose the complex optimization problem and obtains an effective solution using the interactive learning process. Finally, we have conducted extensive simulations, and the results demonstrate that the proposed scheme achieves a fair tradeoff solution between the MCS performance and the profit of individual devices.

• Journal of Institute of Control, Robotics and Systems
• /
• v.18 no.1
• /
• pp.7-12
• /
• 2012

In this paper, we present an effective viewpoint estimation algorithm for the Moving parallax barrier method of 3D display mobile device. Moving parallax barrier is designed to overcome the biggest problem, the limited view angle. To accomplish it, the position of the viewer's eyes or face should be estimated with strong stability and no latency. We focus on these requirements in the poor performance of mobile processors. We used a pre-processing algorithm in order to overcome the various illumination changes. And, we combined the conventional Viola-Jones face detection method and Optical-flow algorithm for robust and stable viewpoint estimation. Various computer simulations prove the effectiveness of the proposed method.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.15 no.2
• /
• pp.286-291
• /
• 2015

For highly scalable NAND flash memory applications, a compact ($4F^2/cell$) nonvolatile memory architecture is proposed and investigated via three-dimensional device simulations. The back-channel program/erase is conducted independently from the front-channel read operation as information is stored in the form of charge at the backside of the channel, and hence, read disturbance is avoided. The memory cell structure is essentially equivalent to that of the fully-depleted transistor, which allows a high cell read current and a steep subthreshold slope, to enable lower voltage operation in comparison with conventional NAND flash devices. To minimize memory cell disturbance during programming, a charge depletion method using appropriate biasing of a buried back-gate line that runs parallel to the bit line is introduced. This design is a new candidate for scaling NAND flash memory to sub-20 nm lateral dimensions.

• IEIE Transactions on Smart Processing and Computing
• /
• v.3 no.6
• /
• pp.425-429
• /
• 2014

This paper proposes a DC-DC Buck-Converter with DT-CMOS (Dynamic Threshold-voltage MOSFET) Switch. The proposed circuit was evaluated and compared with a CMOS switch by both the circuit and device simulations. The DT-CMOS switch reduced the output ripple and the conduction loss through a low on-resistance. Overall, the proposed circuit showed excellent performance efficiency compared to the converter with conventional CMOS switch. The proposed circuit has switching frequency of 1.2MHz, 3.3V input voltage, 2.5V output voltage, and maximum current of 100mA. In addition, this paper proposes a SCP (Short Circuit Protection) circuit to ensure reliability.

• Proceedings of the KIEE Conference
• /
• 1997.11a
• /
• pp.339-341
• /
• 1997

From this first studies, We have investigated the latch-up characteristics of various CMOS well structures possible with high energy ion implantation processes. In this study, we also investigated those of STI(Shallow Trench Isolation} structures with varing n+/p+ spacing and the depth of trench. STI structure is formed by T-SUPREM4 process simulator, and then latch-up simulations for each case were performed by MEDICI device simulator for latch-up immunity improvement. STI is very effective to preventing the degradation of latch-up characteristics as the n+/p+ spacing is reduced. These studies will allow us to evaluate each technology and suggest guidelines for the optimization of latch-up susceptibility.

• Journal of the Korean Society of Safety
• /
• v.32 no.5
• /
• pp.47-53
• /
• 2017

In this study, we propose a new control system that effectively utilizes the interaction effect of control force through the connection of stiffness member for seismic performance enhancement of two adjacent structures equipped with active tuned mass damper (ATMD). The efficiency of the proposed control system is verified by comparing with the existing independent control system through the numerical simulations of the 10th- and 12th-story buildings. From the numerical results, it is confirmed that the proposed method can show similar or better control performance even with more economical control capacity than the existing independent control system. Another advantage is that the existing system does not exhibit the adaptive control performance in emergency of failure of one control device, whereas the proposed system can achieve successful adaptive control performance by economically and efficiently utilizing the interacting control effect through the connection member.

• 한국전산유체공학회:학술대회논문집
• /
• 2011.05a
• /
• pp.202-205
• /
• 2011

A rotating propeller of turboprop aircraft gives much effect on the aerodynamic characteristics of wing such as lift, moment and stall. Specially, a rotating propeller changes the lift and moment characteristics when aircrafts are in landing or take-off condition. In the present paper, 3-dimensional Navier-Stokes simulations for the interaction of propeller and wing were carried out. For rotating propeller, unsteady sliding mesh method was used to simulate a relative motion. For the power effect analysis in landing and take off configurations, double slotted flap was also considered and the aerodynamic characteristics were investigated. It was shown that the propeller slipstream enhanced the lift slope including maximum lift and this enhancement was more dominant with high lift device.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.7
• /
• pp.1141-1149
• /
• 2008

Most faults are single-phase-to-ground fault in ungrounded system. The fault currents of single-phase-to-ground are much smaller than detection thresholds of measurement devices, so detecting single-phase-to-ground faults is difficult and important in ungrounded system. This paper proposed to a FI(Fault Indicator) generation algorithm in ungrounded system. The algorithm just using line-to-line voltage and zero-sequence current detects fault line, fault phase, fault section and FI(Fault Indicator) at terminal device, This paper also proposed to application plan for this algorithm. In the case study, the proposed algorithm has been testified in demo system by Matlab/Simulink simulations.

• Proceedings of the Korea Contents Association Conference
• /
• 2013.05a
• /
• pp.253-254
• /
• 2013

In the preceding studies, an analysis of Saga Prefectural sightseeing information by a self-organizing map (SOM) has been tried. And recent development on information and communication technology (ICT) will help us to access any results via the mobile devices easily. Then, in order to realize this basic idea, development of an application for mobile devices is investigated through some preliminary computer simulations on the standard desktop PC in this article.