• 전력전자학회:학술대회논문집
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• 전력전자학회 2019년도 전력전자학술대회
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• pp.301-302
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• 2019

ITER CS, VS, CC AC/DC Converter는 4상한 동작을 하며, PCS(Plasma Control System)에서 명령하는 출력 전압 제어를 컨버터 교류 입력 전압 변동을 보상하는 Feed-forward 방식을 사용한다. Feed-forward 제어를 위하여 교류 입력 전압에 대한 실시간 정밀 측정이 가능한 RMS 계산이 필요하다. 본 논문은 RMS 연산에 대한 개선된 방법을 제안하면서 시뮬레이션과 실험을 통해 해당 알고리즘을 검증하였고 이에 대한 내용을 논의하고자 한다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.325-330
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• 2012

A single-phase PVPCS(photovoltaic power conditioning system) that contains a single phase dc-ac inverter tends to draw an ac ripple current at twice the out frequency. Such a ripple current may shorten passive elements life span and worsen output current THD. As a result, it may reduce the efficiency of the whole PVPCS system. In this paper, the ripple current propagation is analyzed, and two methods to reduce the ripple current are proposed. Firslyt, this paper presents notch filter with IP voltage controller to reject specific current ripple in single-phase PVPCS. The notch filter can be designed that suppress just only specific frequency component and no phase delay. The proposed notch filter can suppress output command signal in the ripple bandwidth for reducing output current THD. Secondly, for reducing specific current ripple, the other method is feed-forward compensation to incorporate a current control loop in the dc-dc converter. The proposed notch filter and feed-forward compensation method have been verified with computer simulation and simulation results obtained demonstrate the validity of the proposed control scheme.

• 한국정보처리학회논문지
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• 제2권5호
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• pp.619-625
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• 1995

본 연구에서는 역전파(backpropagationlk)학습 알고리즘에 대체될 수 있는 전방향 학습 알고리즘에 준하는 혼합 인식모형을 구성한다. 본 알고리즘은 Nikhil R. Pal (1993)이 제안한 GLVQ(Generalized Learning Vector Quantization)를 이용하여 패턴을 클러스터링 한 다음 비유사성(dissimilarity)을 가진 패턴끼리 재구성(regrouping) 하여 단순 퍼셉트론(simple perceptron)을 이용하여 group별 학습을 한다. 일반적으로 역전파학습인 학습시간이 많이 소요된다는 단점이 있다［1］. 본 알고리즘의 특징으로 는 feed-forward학습이기 때문에 학습시간이 단축될 뿐만 아니라 전체 패턴을 그룹별 로 나누어 학습을 하기 때문에 인식률도 향상 시킬 수 있다. 본 알고리즘에 적용한 데 이타는 250개의 ASCII코드를 16$\times$8격자에 정규화시킨 비트 패턴(bit pattern)을 이용 하였다. 실험결과 250개의 패턴을 10개의 클러스터로 나누어 학습을 시켰을 때 각 클 러스터별 평균반복횟수 94.7회만에 250개의 ASCII코드를 100% 인식할 수 있었다.

• 한국농공학회논문집
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• 제55권2호
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• pp.21-27
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• 2013

The present study explored the way to desalinate seawater for agricultural irrigation using forward osmosis (FO) process using liquid fertilizer as draw solution. FO experiments were performed in a cross flow mode using flat sheet FO membrane. The effect of membrane orientation, flow rate, and draw solution concentration on the performance of forward osmosis was investigated by measuring water flux of forward osmosis membrane. The water flux when the draw solution was placed against the membrane active layer was lower than the water flux when the feed solution was placed against the membrane active layer. This results indicated that the decrease of effective osmotic pressure by dilutive internal concentration polarization was less than that by concentrative internal concentration polarization. Increasing flow rate from 66.7 to 133.1 $cm^3$/min resulted in increase of the water flux when the membrane active layer orient to draw solution and feed solution, respectively. The reduction of resistance to water flow increased water flux at higher flow rate. The water flux of FO membrane increased with increasing draw solution concentration from 10000 to 30000 mg/L. The water flux for $KH_2PO_4$ draw solution was similar to that for commercial fertilizer. Optimization of FO process would contribute to economically desalinate brackish water for agricultural use.

• 대한전자공학회논문지SD
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• 제45권1호
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• pp.20-27
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• 2008

본 논문에서는 비선형 패턴 분류를 위해 FPGA 칩에 신경회로망을 구현하였다. 병렬처리 연산을 위해 순방향 신경회로망이 구현 되었다. 신경망의 학습을 off-line으로 한 다음에 가중치 값들을 저장하여 사용한다. 예로서, AND와 XOR 논리의 패턴 구분이 수행된다. 실험결과를 통해 FPGA에 구현된 신경회로망이 잘 작동하는 것을 검증하였다.

• ETRI Journal
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• 제29권5호
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• pp.679-681
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• 2007

In this letter, we demonstrate a technique for suppression of transients in output bursts of an erbium-doped fiber amplifier (EDFA) in an optical burst network. To suppress the transients, the EDFA is forward-fed by non-fluctuating input utilizing a power-modulated burst control packet channel. Using the technique, we obtained a maximum 1.7 dB reduction in gain transient in the EDFA output, and we transmitted 9.953 Gbps data bursts and 2.488 Gbps burst control packets stably.

• 상하수도학회지
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• 제30권2호
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• pp.131-137
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• 2016

The development of alternative water resources has emerged as an effective method for solving drought of water resources due to extreme weather and increase in water consumption. Recently, in Korea, there has been active research on reverse osmosis desalination technology, wastewater reuse using forward osmosis membranes, and the forward osmosis(FO)-reverse osmosis(RO) hybrid process combining these two technologies. In this study, the basic performance of FO membranes manufactured by three domestic and international manufactures such as Microfilter Co., Ltd., Toray Chemical Korea Inc., and Hydration Technologies Inc., were investigated for wastewater reuse. In addition, as an experiment to select feed solution, the selected membranes were operated 48 consecutive hours using three secondary effluents pretreated by the UF membrane with a pore size of $0.1{\mu}m$ and auto strainer with pore sizes of $1{\mu}m$ and $100{\mu}m$ as feed solution. Although there was not much difference in the operating performance. Thus, the treated water using the $100{\mu}m$ auto strainer was selected as feed solution applied to the assessment.

• 전력전자학회논문지
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• 제20권2호
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• pp.182-192
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• 2015

This study develops a digital control scheme with power factor correction for a front-end converter in an electric vehicle battery charger. The front-end converter acts as the boost-type switching-mode rectifier. The converter assumes the two roles of the battery charger, which include power factor control and robust charging performance. The proposed control scheme consists of a charging control algorithm and a grid current control algorithm. The scheme aims to obtain unity input power factor and robust performance. Based on the linear average model of the converter, a constant-current constant-voltage charging control algorithm that passes through only one proportional-integral controller and a current feed-forward path is proposed. In the current control algorithm, we utilized a second band pass filter, a single-phase phase-locked loop technique, and a duty-ratio feed-forward term to control the grid current to be in phase with the grid voltage and achieve pure sinusoidal waveform. Simulations and experiments were conducted to verify the effectiveness of the proposed control scheme, both simulations and experiments.

• 한국정밀공학회지
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• 제31권10호
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• pp.905-911
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• 2014

A Loss-in-Weight (LIW) feeder, a type of automated measuring device, is a continuous feeder used in many mass production industries. Due to its versatility, there have been constant demands of LIW feeders in food production supply lines as well as chemical and pharmaceutical industries. In this paper, the process of designing a LIW feeder system with better performance will be examined and compared with commercial products. This system is characterized by low pass Butterworth filter and feed forward PI control. The filter is for noise disposal caused by dynamic condition of a LIW feeder. The feed forward PI control, based on linearity feature of feeders, is adequate for stable driving of the system. At the end, a possible evaluation method of LIW system will be proposed to verify the specific achievement of this paper.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.556-560
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• 2007

In this paper, the research results for the improvement of tracking performance of a hydraulic shaking table are presented. A servo-hydraulic shaking table is not only highly nonlinear but also has a lot of time delay. In addition, the shaking table, which consists of multi axial hydraulic actuators, is a MIMO system coupled by kinematics and dynamics of each other's actuators. And it is demanded for the shaking table to track arbitrary trajectories up to high frequency even at the extreme situations such as substantial external loads and large disturbances. For this purpose, an iterative feed-forward control based on the inverse of a measured frequency response function is used for the shaking table. To solve the dynamic coupling, a pressure feedback control as numerical damping is used. It is shown through numerical simulations that the tracking performance of shaking table is improved up to 100Hz.