• Journal of Sensor Science and Technology
• /
• v.32 no.4
• /
• pp.246-251
• /
• 2023

Internet of Things (IoT) systems process signals from various sensors using signal processing algorithms suitable for the signal characteristics. To analyze complex signals, these systems usually use signal processing algorithms in the frequency domain, such as fast Fourier transform (FFT), filtering, and short-time Fourier transform (STFT). In this study, we propose a multi-mode sensor signal processor (SSP) accelerator with an FFT-based hardware design. The FFT processor in the proposed SSP is designed with a radix-2 single-path delay feedback (R2SDF) pipeline architecture for high-speed operation. Moreover, based on this FFT processor, the proposed SSP can perform filtering and STFT operation. The proposed SSP is implemented on a field-programmable gate array (FPGA). By sharing the FFT processor for each algorithm, the required hardware resources are significantly reduced. The proposed SSP is implemented and verified on Xilinxh's Zynq Ultrascale+ MPSoC ZCU104 with 53,591 look-up tables (LUTs), 71,451 flip-flops (FFs), and 44 digital signal processors (DSPs). The FFT, filtering, and STFT algorithm implementations on the proposed SSP achieve 185x average acceleration.

• Proceedings of the KIEE Conference
• /
• 2007.04a
• /
• pp.267-269
• /
• 2007

PLL(Phase Locked Loop) are widely used circuit technique in modern electronic systems. In this paper, We propose the low voltage and high speed PLL. We design the PFD(Phase Frequency Detector) by using TSPC (True Single Phase Clock) circuit to improve the performance and solve the dead-zone problem. We use CP(Charge Pump} and LP(Loop filter) for Negative feedback and current reusing in order to solve current mismatch and switch mismatch problem. The VCO(Voltage controlled Oscillator) with 5-stage differential ring oscillator is used to exact output frequency. The divider is implemented by using D-type flip flops asynchronous dividing. The frequency divider has a constant division ratio 32. The frequency range of VCO has from 200MHz to 1.1GHz and have 1.7GHz/v of voltage gain. The proposed PLL is designed by using 0.18um CMOS processor with 1.8V supply voltage. Oscillator's input frequency is 25MHz, VCO output frequency is 800MHz and lock time is 5us. It is evaluated by using cadence spectra RF tools.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.11C
• /
• pp.1132-1138
• /
• 2002

This paper proposes a reducing power consumption of a scheduling algorithm for optimal selection of supply voltage. In scheduling of reduction power consumption, we determine the control steps of operations to be executed by exploiting the possibility of using variable voltage levels to reduce power consumption. In the optimal selection of supply voltage binding, we minimize the main factor of the power consumption of the switching activity on the registers using a graph coloring technique. From a set of experiments using high-level benchmark examples, we show that the proposed algorithm prefer to use optimal selection supply voltages rather than uniformed single voltage is effective in reducing power consumption.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.20 no.6
• /
• pp.498-508
• /
• 2015

In the simulation of photovoltaic (PV) power conditioning systems, PSIM is a widely accepted circuit simulation platform because of its fast speed and C-code support. PSIM provides two kinds of generic PV panel models: functional model and physical model. Whereas the functional model simulates PV in the standard test condition (STC) only, the physical model can emulate changing PV characteristics under varying temperatures and irradiation conditions and is thus more suitable for system simulation. However, the physical model requires complicated parameters from users, and thus it is prone to errors and is difficult to use. In this study, a new PSIM model for PV is presented to solve these problems. The proposed model utilizes manufacturers' datasheet values specified under STC only and excludes user-defined information from input parameters. To achieve good accuracy even in varying environmental conditions, single-diode model parameters are successively tuned to a time-varying virtual datasheet. Comparison with a conventional physical model shows that the proposed model provides more accurate simulation according to error analysis based on the EN50530 standard.

• Journal of Power Electronics
• /
• v.11 no.3
• /
• pp.311-318
• /
• 2011

LCL filters installed at converter outputs offer a higher harmonic attenuation than L filters. However, as a three order resonant circuit, it is difficult to stabilize and has a risk of oscillating with the power grid. Therefore, careful design is required to damp LCL resonance. Compared to a passive damping method, an active damping method is a more attractive solution for this problem, since it avoids extra power losses. In this paper, the damping capabilities of capacitor current, capacitor voltage, and grid-side current feedback methods, are analyzed under the discrete-time state-space model. Theoretical analysis shows that the grid-side current feedback method is more suitable for use in active power filters, because it can damp LCL resonance more effectively than the other two methods when the ratio of the resonance and the control frequency is between 0.225 and 0.325. Furthermore, since there is no need for extra sensors for additional states measurements, this method provides a cost-efficient solution. To support the theoretical analysis, the proposed method is tested on a 7-kVA single-phase shunt active power filter.

• Journal of Digestive Cancer Research
• /
• v.5 no.1
• /
• pp.37-43
• /
• 2017

Laparoscopic cholecystectomy is of one the most common general surgical operations performed today. Concomitant choledocholithiasis occurs in roughly 10-20% of patients with symptomatic gallstones. Laparoscopic bile duct exploration (LBDE) offers a single-stage minimally-invasive solution to the management of choledocholithiasis. LBDE may be performed either via the transcystic route or via laparoscopic choledochotomy. A number of strategies to improve success are available to the surgeon to help in the problem of complicated choledocholithiasis, these range from simple maneuvers to the use of laser or mechanical lithotriptors. With the advances in laparoscopic surgery, it is also possible to handle complex surgical conditions such as Mirizzi syndrome or recurrent pyogenic cholangitis laparoscopically, even though these have yet to be accepted as standard of care. Following laparoscopic choledochotomy, options for closure include: primary closure, closure over a T-tube, and closure over an endobiliary stent. T-tube placement has been associated with increased operating time and hospital length of stay compared to primary closure, with no significant differences in morbidity. Based on the available literature, LBDE appears comparable to ERCP with regards to procedural efficacy and morbidity. LBDE remains relevant to the general surgeon and is best viewed as being complementary to endoscopic therapy in the management of choledocholithiasis.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.2
• /
• pp.237-242
• /
• 2009

Comparing with fixed-type Robots, Mobile Robots have the advantage of extending their workspaces. But this advantage need some sensors to detect mobile robot's position and find their goal point. This article describe the navigation teaching method of mobile robot using omni-directional position detection system. This system offers the brief position data to a processor with simple devices. In other words, when user points a goal point, this system revise the error by comparing its heading angle and position with the goal. For these processes, this system use a conic mirror and a single camera. As a result, this system reduce the image processing time to search the target for mobile robot navigation ordered by user.

• The Journal of Korean Physical Therapy
• /
• v.15 no.3
• /
• pp.202-222
• /
• 2003

Chronic upper extremity hemiparesis is a leading cause of functional disability after stroke. The purpose of this study were to identify effects of a 6weeks repetitive bilateral arm training on upper motor function and the reorganization of motor network. Four chronic stroke patients participated in this study. They performed for 6 consecutive weeks, 3 days a week, 30 minutes a day. In the single group study, four 5-minute periods per session of bilateral arm training were performed with the use of a custom-designed arm training machine. The results of this study was as follows. 1. Following the 6weeks period of RBAT, patient exhibited a improvement in FMA and BBT. 2. Following the 6weeks period of RBAT, it showed improvement in reaching time, symbol digit substitution and finger tapping speed of KCNT. 3. fMRI activation after RBAT showed a focal map in lesional cortical area and perilesional motor areas. These fMRI data suggest that hemodynamics response to RBAT reflect sensorimotor reorganization in contralateral hemisphere. In conclusion, these date suggest that improved upper extremity function induced by repetitive bilateral arm training after stroke is associated with reorganization of motor network as a neural basis for the improvement of paratic upper extremity function.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.42 no.12
• /
• pp.95-102
• /
• 2005

This paper is purpose for improvement performance wireless lan of IEEE802.11a/b/g. Access point utilized a single server, multi-queuing system, FIFS system model to adapted priority multi-bufferto be alteration packet type. The main purpose of the paper improve the transmission rate and the performance of access point to settle transmission delay for load in MAC, has priority multi-buffer. We use experimentation to obtain our model of the access point and buffer-related parameters. Using our test design, we are able to extract the parameters of an analytic equation giving the average service time of a packet as a function of packer IP payload.

• Restorative Dentistry and Endodontics
• /
• v.23 no.1
• /
• pp.213-222
• /
• 1998

Advisor: Prof. The quality of apical seal obtained with 3 different gutta-percha obturation techniques was compared in 49 recently extracted single rooted teeth. The root canals were instrumented using step-back technique and obturated with laterally condensed gutta-percha, Continuous Wave gutta-percha, and hybrid technique. Teeth were suspended in black India ink for 7 days, cleared, and then examined under a stereomicroscope at ${\times}10$ magnification. The results were as follows; 1. All experimental groups produced favorable apical seal. 2. The mean leakage was $0.23{\pm}0.25mm$ for group 1, $0.17{\pm}0.21mm$ for group 2, and $0.19{\pm}0.23mm$ for froup 3, but there was no statistical difference amoung them. Within the limits of the results of this experiment, the Continuous Wave gutta-percha obturation technique demonstrated relatively favorable apical sealing effect and shorter obturation time. Thus, it is thought that this obturation technique is a acceptable method for clinical use but further studies on this metter should be conducted.