• Journal of Power Electronics
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• 제19권4호
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• pp.835-845
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• 2019

This paper presents a robust-optimal control strategy to improve the output-voltage error-tracking and control capability of a DC-DC boost converter. The proposed strategy employs an optimized Fractional-order Proportional-Integral (FoPI) controller that serves to eliminate oscillations, overshoots, undershoots and steady-state fluctuations. In order to significantly improve the error convergence-rate during a transient response, the FoPI controller is augmented with a pre-stage nonlinear error-modulator. The modulator combines the variations in the error and error-derivative via the signed-distance method. Then it feeds the aggregated-signal to a smooth sigmoidal control surface constituting an optimized hyperbolic secant function. The error-derivative is evaluated by measuring the output-capacitor current in order to compensate the hysteresis effect rendered by the parasitic impedances. The resulting modulated-signal is fed to the FoPI controller. The fixed controller parameters are meta-heuristically selected via a Particle-Swarm-Optimization (PSO) algorithm. The proposed control scheme exhibits rapid transits with improved damping in its response which aids in efficiently rejecting external disturbances such as load-transients and input-fluctuations. The superior robustness and time-optimality of the proposed control strategy is validated via experimental results.

• 대한방사선기술학회지:방사선기술과학
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• 제44권1호
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• pp.31-37
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• 2021

This study aim of quantitative assessment of Noise Power Spectrum(NPS) and image characteristics of by acquired the optimal image for noise characteristics and quality assurance by using magnetic resonance imaging(MRI). MRI device was (MAGNETOM Vida 3.0T MRI; Siemense healthcare system; Germany) used and the head/neck shim MR receive coil were 20 channels coil and a diameter 200 mm hemisphere phantom. Frequency signal could be acquired the K-space trajectory image and white image for NPS. The T2 image highest quantitatively value for NPS finding of showed the best value of 0.026 based on the T2 frequency of 1.0 mm-1. The NPS acquired of showed that the T1 CE turbo image was 0.077, the T1 CE Conca2 turbo image was 0.056, T1 turbo image was 0.061, and the T1 Conca2 turbo image was 0.066. The assessment of NPS image characteristics of this study were to that could be used efficiently of the MRI and to present the quantitative evaluation methods and image noise characteristics of 3.0T MRI.

• 한국전기전자재료학회논문지
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• 제34권2호
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• pp.121-125
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• 2021

The machine vision technology has been widely used in the industrialized nations like the United States, Japan, and EU in the various industries from the late 1980s. Machine vision inspection system mainly consists of a camera, optics, illumination and an image acquisition system. Optimization of the illumination light source is very important. This paper shows a comparison between Pulse Width Modulation (PWM) control and strobe control in driving LED lighting system for machine vision. PWM control method has problems such as a temperature rising of LED and a flickering in image measurement for inspection. In contrast, the proposed strobe control method can suppress the temperature of LED light source below 40℃. Also, it can remove the flickering problem through a synchronization between a frame grabber and a camera shutter. Finally, the strobe control method was shown to extract clearer images with a high precision compared to PWM control method.

• KEPCO Journal on Electric Power and Energy
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• 제6권4호
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• pp.405-411
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• 2020

In this paper, we designed the COS MEMS system for sensing the falling detection and explosive noise of fuse link in COS (Cut Out Switch) installing on the power distribution. This system analyzed the failure characteristics and an instantaneous breakdown of power distribution. Therefore, our system strengths the industrial competence and guaranties the stable power supply. In this paper, we applied BLE (Bluetooth Low Energy) technology which is suitable protocol for low data rate, low power consumption and low-cost sensor applications. We experimented with LSM6DSOX which is system-in-module featuring 3 axis digital accelerometer and gyroscope boosting in high-performance mode and enabling always-on low-power features for an optimal motion for the COS fuse holder. Also, we used the MP34DT05-A for gathering an ultra-compact, low power, omnidirectional, digital MEMS microphone built with a capacitive sensing element and an IC interface. The proposed COS MEMS system is developed based on nRF52 SoC (System on Chip), and contained a 3-axis digital accelerometer, a digital microphone, and a SD card. In this paper of experiment steps, we analyzed the performance of COS MEMS system with gathering the accelerometer raw data and the PDM (Pulse Data Modulation) data of MEMS microphone for broadcasting the failure of COS status.

• ETRI Journal
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• 제45권2호
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• pp.193-202
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• 2023

We demonstrate the transmission of uncompressed 4K videos over the photonics-based terahertz (THz) wireless link using a directly modulated distributed feedback laser diode (DFB-LD). For optical heterodyne mixing and data modulation, a DFB-LD was employed and directly modulated with a 5.94-Gb/s non-return-to-zero signal, which is related to a 6G-serial digital interface standard to support ultra-high-definition video resolution. We derived the optimal frequency of the THz carrier by varying the wavelength difference between DFB-LD output and Tunable LD output in the THz signal transmitter to obtain the best transmission performances of the uncompressed 4K video signals. Furthermore, we exploited the negative laser-to-filter detuning for the adiabatic chirp management of the DFB-LD by the intentional discrepancy between the center wavelength of the optical band-pass filter and the output wavelength of the DFB-LD. With the help of the abovementioned methods, we successfully transmitted uncompressed 4K video signals over the 2.3-m wireless transmission distance without black frames induced by time synchronization error.

• ETRI Journal
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• 제46권2호
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• pp.184-193
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• 2024

This paper presents the performance evaluation of an amplify-and-forward (AF) relay-assisted multiuser multiple input-multiple output (MU-MIMO) downlink transmission system for correlated fading channels. The overall system performance was improved by incorporating a double-quadrature spatial modulation (DQSM) scheme. The bit error rate (BER) performance and detection complexity of the AF-MU-MIMO-DQSM system were analyzed and compared with those of a conventional AF-MU-MIMO system under the same conditions and parameters. The results showed that the correlated fading channel severely affected the performance of systems with higher spectral efficiency (SE). Considering an SE of 12 bpcu/user, the AF-MU-MIMO-DQSM system yielded a gain of up to 3 dB in BER performance compared with that of its conventional counterpart for the analyzed cases. In terms of detection complexity, the AF-MU-MIMO-DQSM system showed a reduction of up to 56 % compared with that of the conventional system for the optimal maximum likelihood detection criterion.

• 전자공학회논문지
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• 제52권5호
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• pp.3-9
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• 2015

기존의 무선통신시스템에서는 무선채널에서의 데이터 전송 성능 향상을 위해 시스템 각 계층의 특성에 적합한 재전송 방식을 사용한다. 이때 재전송 방식은 해당 계층에서 독립적으로 동작하며, 무선통신시스템의 종단 간 성능에는 관계없이 각 계층별로 정해진 파라미터에의해 동작하게 된다. 이와 같은 파라미터는 무선통신시스템의 종단 간 성능을 고려하지 않기 때문에 한정된 무선채널자원 및 네트워크 자원을 효율적으로 활용하기 위한 최적의 시스템 파라미터를 설계하기 어렵다. 따라서 각 서비스 별로 정해진 종단 간 QoS(Quality of Service) 요구사항을 만족시키기에 적합한 재전송 방식의 파라미터를 설계하기 위해서는 무선통신시스템의 종단 간 성능 분석이 필요하다. 본 논문에서는 다 계층 재전송 방식을 사용하는 무선통신시스템의 종단 간 성능을 수학적으로 분석하고, 모의실험을 통해 MAC(Medium Access Control) 계층과 전송계층에서 데이터 전송 성능을 도출한다. 또한 성능평가 결과를 바탕으로 사용자에게 제공되는 각 서비스 클래스의 특성에 적합한 재전송 방식과 파라미터 값을 설정하도록 한다. 모의실험 결과, HARQ(Hybrid Automatic Repeat reQuest)와 AMC(Adaptive Modulation and Coding)를 결합한 방식의 경우 지연에 민감한 서비스에 유리하며, ARQ(Automatic Repeat reQuest)와 AMC를 결합한 방식은 평균 전송지연시간에 영향을 받지 않는 서비스에 유리하다. 또한 TCP(Transmission Control Protocol)는 지연에 민감하지 않은 서비스에서만 사용 가능하다.

• The Korean Journal of Physiology and Pharmacology
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• 제19권2호
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• pp.167-175
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• 2015

A retinal prosthesis is being developed for the restoration of vision in patients with retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Determining optimal electrical stimulation parameters for the prosthesis is one of the most important elements for the development of a viable retinal prosthesis. Here, we investigated the effects of different charge-balanced biphasic pulses with regard to their effectiveness in evoking retinal ganglion cell (RGC) responses. Retinal degeneration (rd1) mice were used (n=17). From the ex-vivo retinal preparation, retinal patches were placed ganglion cell layer down onto an $8{\times}8$ multielectrode array (MEA) and RGC responses were recorded while applying electrical stimuli. For asymmetric pulses, 1st phase of the pulse is the same with symmetric pulse but the amplitude of 2nd phase of the pulse is less than $10{\mu}A$ and charge balanced condition is satisfied by lengthening the duration of the pulse. For intensities (or duration) modulation, duration (or amplitude) of the pulse was fixed to $500{\mu}s$($30{\mu}A$), changing the intensities (or duration) from 2 to $60{\mu}A$(60 to $1000{\mu}s$). RGCs were classified as response-positive when PSTH showed multiple (3~4) peaks within 400 ms post stimulus and the number of spikes was at least 30% more than that for the immediate pre-stimulus 400 ms period. RGC responses were well modulated both with anodic and cathodic phase-1st biphasic pulses. Cathodic phase-1st pulses produced significantly better modulation of RGC activity than anodic phase-1st pulses regardless of symmetry of the pulse.

• 대한물리치료과학회지
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• 제8권1호
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• pp.745-758
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• 2001

The purpose of study to phenomenological examine and the mechanism regarding the gene(DNA, RNA, Protein) and sports to studied, analyzed. and evaluated. This review considers the evidence for genetic effects in several determinants of endurance performance and resistance performance, namely: body measurements and physique, body fat pulmonary functions, cardiac and circulatory functions, muscle characteristics. substrate utilization, maximal aerobic power and other. Moreover, the response to aerobic training of indicators aerobic work metabolism and endurance performance is reviewed, with emphasis on the specificity of the response and the individual differences observed in training ability. This study indicate that improvement of 'Enhancer Action' in RNA genes changed by exercise or sports. Moreover exercise was effect on Central Dogma with DNA makes RNA makes Protein. and think that occurred with exercise influence on skeletal muscle into cell have to Myosin Heavy Chain (MHC) changed was after exercise performance, which accompanied into skeletal muscle that were exercise-induces gene-modulation that is, take gene mutations. This study known that existed hormone(epinephrine)-immune system with interaction. Exercise were altered insulin binding and MAP Kinase signaling increased into immune cells. This review suggested that the high rate of glutamine utilization by cells of the immune system serves to maintain a high intra cellular concentration of the intermediates of biosynthetic pathways such that optimal rates of DNA, RNA and protein synthesis can be maintained. In the absence of glutamine, lymphocytes do not proliferate in vitro: proliferation increase greatly as the glutamine concentration increase. Glutamine is synthesized in skeletal muscle. Skeletal muscle and plasma glutamine levels are lowered by sepsis, injury, bums, surgery and endurance exercise and in the overtrained athlete. The study of result show that production of ET-1 is markedly increased tissue specifically in the heart by exercise without appreciable changes in endothelin-converting enzyme and endothelial receptor expressions, suggest that myocardial ET-1 may participate in modulation of cardiac function during exercise. Conclusionally, this study indicate that improvement of 'Enhancer Action' in RNA genes changed by exercise or sports. Moreover exercise was effect on Central Dogma with DNA makes RNA makes Protein. This study is expected to contribute the area of sports science, medicine, hereafter more effort is required to establish the relation between gene alters and exercise amount.

• KSBB Journal
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• 제20권6호
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• pp.453-457
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• 2005

우리는 황결핍 환경에서 C. reinhardtii에 의한 수소생산성을 증진시키기 위해 황성분의 농도가 수소생산에 미치는 영향을 조사하였고, 그 결과를 이용하여 황 재첨가에 의한 연속적인 수소생산을 수행하였다. $MgSO_4$ 용액을 농도별(0, 15, 30, 60, 120 ${\mu}M$)로 희석하여 황결핍 초기에 첨가하였을 때, 최적 황농도는 $30{\mu}M$로서 236 mL $H_2/L$ culture를 생산하였다. 황결핍 시 황성분의 첨가는 PSII 활성화에 기여하여 hydrogenase가 수소합성에 이용할 수 있는 전자를 다량 발생시키기 때문이다. 그러나 초기에 첨가해 준 황농도가 너무 높으면, 황결핍 시간이 지연($MgSO_4\;60{\mu}M$의 경우) 되거나 황결핍이 일어나지 않기($MgSO_4\;120{\mu}M$의 경우) 때문에 hydrogenase가 유도되지 않는다. 따라서 수소생산량이 다른 농도에 비해 감소하거나 수소가 전혀 생산되지 않았다. 연속적인 수소생산을 위한 황성분 재첨가는 총 4회 수행되었고, 발생된 총 수소생산량은 625 m/L $H_2/L$ culture였다. 그러나 황성분을 재첨가해 줄 때마다 수소생산량은 점차 감소되었다. 이것은 황결핍 조건에서 단일항 산소에 의한 chlorophyll 파괴 및 세포 수의 감소, 또한 배양액 내의 pH의 증가 때문에 수소생산이 감소된 것으로 사료된다. 따라서 황결핍 조건에서 조류를 이용한 연속적인 수소생산 공정을 개발하기 위해서 황성분 첨가시기를 조절하여 세포의 사멸을 방지하고, 배양액내 pH 조절을 위한 다양한 buffer 첨가 실험 등 수소생산성을 지속적으로 유지할 수 있는 다양한 연구가 필요하다.