• 한국지능시스템학회논문지
• /
• 제13권4호
• /
• pp.397-402
• /
• 2003

본 논문은 디지털 재설계 기법을 이용한 펄스폭변조(PWM： pulse-width-modulation) 제어기 설계 기법을 제안한다. 디지털 재설계 기법은 잘 설계된 아날로그 제어기를 상태 정합(state-matching) 이라는 측면에서 그 제어 성능을 보장하도록 일반적인 펄스크기변조(PAM: pulse-amplitude-modulation) 디지털 제어기로 변환하는 기법이다 유사한 개념으로 재설계된 PAM 디지털 제어기는 등가 영역의 원리(equivalent area principle)를 사용하여 PWM 제어기로 변환된다. 제안된 PWM 제어기법의 효용성을 검증하기 위하여 인공위성의 자세제어 시스템의 모의실험의 예를 보인다.

• 한국지능시스템학회논문지
• /
• 제14권6호
• /
• pp.726-731
• /
• 2004

본 논문은 비선형 시스템을 위한 효율적인 펄스 폭 변조 (PWM: pulse-width-modulation) 제어기 설계 기법을 제안한다. 이를 위하여 우선 지능형 디지털 재설계 기법을 사용하여 잘 설계된 아날로그 제어기를 상태 정합(state-matching) 이라는 측면에서 그 제어 성능을 보장하도록 일반적인 펄스 크기 변조(PAM: pulse-amplitude-modulation) 디지털 제어기로 변환한다. 재설계된 지능형 PAM 디지털 제어기는 등가 영역의 원리(equivalent area principle)를 사용하여 PWM 제어기로 변환된다. 제안된 PWM 제어기법의 효용성을 검증하기 위하여 인공위성의 자세제어 시스템의 모의실험의 예를 보인다.

• Journal of Power Electronics
• /
• 제12권6호
• /
• pp.992-1002
• /
• 2012

In this paper, the series chopper based power train for electric vehicle is proposed for aiming the increase of one battery charge driving distance. Both the motor test bench based experiments and the chassis dynamo based experiments are tested and then analyzed for EV driving performance that the proposed power train with SAZZ chopper and Quasi-PAM control scheme is compared with or without the series chopper. It is confirmed through two kinds of experimental analyses that the series chopper power train for EV can be useful to extend the driving distance if the high efficiency and the low weight of chopper are satisfied.

• 제어로봇시스템학회논문지
• /
• 제10권5호
• /
• pp.411-414
• /
• 2004

In this paper, a power controller and 3 phase voltage source inverter are proposed for the improvement of weldability of large scaler Mash seam welder. The welder system is designed for the low cost and the improvement of weldability. For this system, the thyristor convertor has performed constant current controlling in the output terminal by using PAM type inverter. We have simulated our algorithm and made a prototype welder for experiment. Through the experiment, we have confirmed the improvement of weldability of our system.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
• /
• pp.654-657
• /
• 1998

This paper is described a digital implementation of a pulse area modulation (PAM) method for a unity-power-factor buck-boost converter. A digital controller is designed and implemented by a Digital Signal Processor(DSP) to replace the analog control circuit for PAM. Experimental results are presented and compared with simulations.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
• /
• pp.366-373
• /
• 1998

In this paper, a new control strategy to reduce switching losses in three-phase voltage-source PWM converters is proposed according to Modified-Period-Average-Model (MPAN). The basic concept of this strategy is aimed at calculating the phase control voltages for controlling the source currents to be sinusoidal and in phase with the source voltages, and reducing the number of switching in each period. The phase control voltages of Period-Average-Model(PAM) is obtained according to analyzing the operation of PWM converter. In order to reduce the sensitivity to system parameters in PAM, MPAM is deduced. Then a square wave whose frequency is three times of utility frequency is added to the phase control voltages derived from MPAM. The control strategy reduces the switching losses since there exists about one-third blanking time for every phase in one period. The theoretical derivation and the control strategy are experimentally verified on a 2.5 kW three-phase voltage source converter.

• Journal of Power Electronics
• /
• 제10권5호
• /
• pp.477-484
• /
• 2010

A pulse width modulation-voltage source inverter (PWM-VSI) is used for variable speed permanent magnet synchronous motor (PMSM) drives. The PWM-VSI fed PMSM has two major disadvantages. Firstly, the PWM-VSI DC-link voltage limits the magnitude of the PMSM terminal voltage. As a result, the motor speed is restricted. Secondly, in a low speed range, the PWM-VSI modulation index declines. This is caused by a high DC-link voltage and a low terminal voltage ratio. As a result, the distortion of the voltage command and the stator current are increased. This paper proposes an optimal pulse amplitude modulation (PAM) control which can adjust the inverter DC-link voltage by using a buck-boost DC-DC converter. At a low speed range, the proposed system can reduce the distortion of the voltage command, which improves the stator current waveform. Also, the allowable speed range is extended. In order to verify the proposed method, experimental results are provided to confirm the simulation results.

• 한국토양비료학회지
• /
• 제49권5호
• /
• pp.440-448
• /
• 2016

Nonpoint sources of pollution (NPS) is defined as diffuse discharges of pollutants (e.g., nutrient, pesticide, sediment, and enteric microorganism) throughout the natural environment and they are associated with a variety of farming practices. Previous studies found that water soluble anionic polyacrylamide (PAM) is one of the highly effective measures for enhancing infiltration, reducing runoff, preventing erosion, controlling nonpoint source of pollutants, and eventually protecting soil and water environment. Potential benefits of PAM treatment in agricultural soil and water environments have been revealed by many research and they include low cost, easy and quick application, and suitability for use with other Best Management Practices (BMPs) for NPS control. This study reviews the various applications of PAM and discusses its further potentials in agricultural environment.

• Journal of Nutrition and Health
• /
• 제49권4호
• /
• pp.241-246
• /
• 2016

Purpose: Aloe-emodin (AE), an ingredient of aloe, is known to exhibit anti-inflammatory activities. However, little is known about the underlying molecular mechanisms of its inflammatory modulatory activity in vitro. In the present study, we investigated the anti-inflammatory potential of AE using $Pam_3CSK_4$-stimulated macrophages. Methods: RAW 264.7 macrophages were treated with AE (0~20 mM) for 1 h, followed by treatment with $Pam_3CSK_4$ for 1 h. After incubation, mRNA expression levels of cytokines were measured. The effect of AE on TLR2-related molecules was also investigated in $Pam_3CSK_4$-stimulated RAW 264.7 macrophages. Results: AE attenuated $Pam_3CSK_4$-stimulated expression of proinflammatory cytokines, including tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$), interleukin-6 (IL-6), and interleukin-$1{\beta}$ ($IL-1{\beta}$) in RAW 264.7 macrophages. Two concentrations of AE ($10{\mu}M$ and $20{\mu}M$) effectively reduced mRNA expression of TLR2 by 41.18% and 54.43%, respectively, compared to that in control cells (p < 0.05). AE also decreased nuclear factor-kappa B ($NF-{\kappa}B$) activation and mitogen-activated protein kinase (MAPK) phosphorylation. Phosphorylation levels of ERK1/2, p38, and JNK were markedly reduced by $20{\mu}M$ AE. In particular, AE decreased phosphorylation of ERK in a dose-dependent manner in $Pam_3CSK_4$-stimulated RAW 264.7 macrophages. Conclusion: Our data indicate that AE exerts its anti-inflammatory effect by suppressing TLR2-mediated activation of $NF-{\kappa}B$ and MAPK signaling pathways in macrophages.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2011년도 학술발표회
• /
• pp.336-336
• /
• 2011

본 연구에서는 강우시 경사지 밭에서 발생하는 토양유실량을 저감하기 위하여 지표피복재의 유무와 강우강도를 달리하여 실외인공강우 실험을 통하여 평가하였다. 인공강우 실험은 경사도 28%와 각 시험포는 $5\times30m$의 크기로 strawmat+PAM+sawdust, control(bare), strawmat+PAM, strawmat+PAM+rice husks를 4개 조성하고, 각 시험포는 하단부에 강우유출수를 채취할 수 있는 설비(flume)를 설치하였다. 대조구 실험을 위하여 각 시험포에서 발생하는 직접유출량과 유사량을 비교 분석하였다. 시험포의 토양은 양질사토로 일반 고랭지 밭의 흙과 동일한 성질을 가지고 있는 토양을 사용하였고, 지표 피복처리는 straw mat, saw dust, rice husk 그리고 PAM 등 4개의 재료를 사용하였다. 인공강우 실험은 1차 10월 18일, 2차 10월 24일, 3차 10월 30일, 4차 11월 7일로 총 21일간 각각 약 1주일의 간격을 두고 실시하였으며 인공강우 시험기의 강우강도는 각 31.1 ~ 44.4 mm/hr로 모의하였다. 연구결과 시험포에서 발생한 유출량은 지표피복을 하지 않은 대조구 시험포보다 지표를 피복한 시험포에서 약 15.7 ~ 19%의 감소한 것으로 나타났다. 유사량은 대조구 시험포보다 약 93.1 ~ 99.3% 감소한 것으로 나타났으며, 유출량과 유사량은 straw mat+PAM+sawdust와 straw mat+PAM+rice husk를 적용한 시험포에서 저감효과가 큰 것으로 나타났다. 이와 같이 지표피복처리는 강우가 발생하였을 때 강우타격력의 감소와 유출수의 유속감소 그리고 침투능을 증가하는 역할을 하여 경사지, 농경지 및 공사현장에서 토양 유실을 저감하며, 하천이나 강으로 유입되는 탁수량의 저감에 큰 효과가 있을 것으로 판단된다.