Characteristic analysis of parallel-rotor hybrid generator based on exciter types

Woo, Hyeon Myeong,Lee, Dong-Hee The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.3

In this paper, a characteristic analysis and a performance comparison of a permanent magnet (PM) exciter and a conventional winding exciter for a parallel-rotor-type hybrid generator is presented. The proposed rotor of the hybrid generator comprises two separate structures, a PM and a field winding. The two rotors are attached in parallel to improve the efficiency and self-starting characteristics. Using this configuration, the PM rotor produces base flux to generate enough no-load voltage and the field winding rotor is used to regulate that output voltage. Because of the PM rotor flux, the automatic voltage regulator can self-start the generator by taking the voltage induced by the PM flux, regardless of the exciter. The self-start capability, dynamic response and efficiency of both exciters are compared and investigated. It can be confirmed through experiments that the PM exciter shows better efficiency and dynamic response with reduced mechanical complexity.

Fate and fouling characteristics of fluorescent dissolved organic matter in ultrafiltration of terrestrial humic substances

Quang, V.L.,Kim, H.C.,Maqbool, T.,Hur, J. Pergamon Press 2016 CHEMOSPHERE - Vol.165 No.-

Ultrafiltration (UF) membrane fouling caused by terrestrial input of dissolved organic matter (DOM), especially during high flood periods, is poorly understood. In this study, we examined the fouling characteristics of three different terrestrial humic substances (HS) on regenerated cellulose (RC) UF membranes with the pore sizes of 30 k-3 kDa via conventional bulk HS measurements as well as an advanced fluorescence spectroscopy. The fluorescence excitation-emission matrix coupled with parallel factor analysis (EEM-PARAFAC) identified one protein-like (C1) and three humic-like fluorescent components (C2-C4) from soil and leaf-derived HS. The fate of the different fluorescent components was individually tracked for the UF processes. The higher removal rates were found generally on the order of high molecular weight (HMW) C1 to smaller sized humic-like components (C4 > C3 > C2) regardless of the HS sources, implying the importance of HS molecular sizes on the UF operation. Among the humic-like components, C2 was the most associated with irreversible fouling, while other two humic-like components contributed more to reversible fouling. For soil-derived HS, C4 can be suggested as a good surrogate for membrane fouling, as evidenced by the highest correlation between the removal rates and the total fouling indices among the tested HS variables including conventional bulk parameters. Our study demonstrated a promising application of EEM-PARAFAC for probing membrane fouling of terrestrial DOM, which provided additional insight into the fate of different fluorescent components on the UF processes.

영주댐 유사조절지 상류의 용존유기물 (Dissolved Organic Matter) 특성과 물리 . 화학 및 생물학적 환경 요인과의 연관성 연구

오혜지,김도균,최지수,채연지,오종민,신경훈,최광순,김동균,장광현 한국하천호수학회 2021 생태와 환경 Vol.54 No.4

A sediment control dam is an artificial structure built to prolong sedimentation in the main dam by reducing the inflow of suspended solids. These dams can affect changes in dissolved organic matter (DOM) in the water body by changing the river flow regime. The main DOM component for Yeongju Dam sediment control of the Naeseongcheon River was analyzed through 3D excitation-emission matrix (EEM) and parallel factor (PARAFAC) analyses. As a result, four humic-like components (C1~C3, C5), and three proteins, tryptophan-like components (C2, C6~C7) were detected. Among DOM components, humic-like components (autochthonous: C1, allochthonous: C2~C3) were found to be dominant during the sampling period. The total amount of DOM components and the composition ratio of each component did not show a difference for each depth according to the amount of available light (100%, 12%, and 1%). Throughout the study period, the allochthonous organic matter was continuously decomposing and converting into autochthonous organic matter; the DOM indices (fluorescence index, humification index, and freshness index) indicated the dominance of autochthonous organic matter in the river. Considering the relative abundance of cyanobacteria and that the number of bacteria cells and rotifers increased as autochthonous organic matter increased, it was suggested that the algal bloom and consequent activation of the microbial food web was affected by the composition of DOM in the water body. Research on DOM characteristics is important not only for water quality management but also for understanding the cycling of matter through microbial food web activity.

Characteristics of intracellular algogenic organic matter and its reactivity with hydroxyl radicals

Lee, Doorae,Kwon, Minhwan,Ahn, Yongtae,Jung, Youmi,Nam, Seong-Nam,Choi, Il-hwan,Kang, Joon-Wun Elsevier 2018 Water research Vol.144 No.-

<P><B>Abstract</B></P> <P>The aim of this study was to investigate the reactivity of intracellular algogenic organic matter (IOM) with hydroxyl radicals (·OH), a key reaction species in advanced oxidation processes. IOM was extracted from two green algae, <I>Chlamydomonas reinhardtii</I> and <I>Scenedesmus</I> sp., and two blue-green algae, <I>Anabaena</I> sp. and <I>Microcystis aeruginosa</I> using a freeze–thaw method. The second-order rate constants of the extracted IOM with ·OH were determined as 7.95 × 10<SUP>8</SUP> M<SUB>C</SUB> <SUP>−1</SUP> s<SUP>−1</SUP> (<I>Chlamydomonas reinhardtii</I>), 6.71 × 10<SUP>8</SUP> M<SUB>C</SUB> <SUP>−1</SUP> s<SUP>−1</SUP> (<I>Scenedesmus</I> sp.), 4.02 × 10<SUP>8</SUP> M<SUB>C</SUB> <SUP>−1</SUP> s<SUP>−1</SUP> (<I>Anabaena</I> sp.), and 4.45 × 10<SUP>8</SUP> M<SUB>C</SUB> <SUP>−1</SUP> s<SUP>−1</SUP> (<I>Microcystis aeruginosa</I>). These rate constants were significantly higher than values reported for dissolved organic matter in various water sources. This implies that IOM formation during algal bloom season could change the ·OH water matrix demand and adversely affect the performance of advanced oxidation processes. To investigate the physical and chemical composition characteristics of IOM and their relationship to the rate constants determined for the reaction between IOM and ·OH, liquid chromatography-organic carbon detection (LC-OCD) and fluorescence excitation-emission matrix & parallel factor analysis (FEEM-PARAFAC) were used. The IOM mainly consisted of low molecular weight (LMW) matter and protein-related compounds, as evidenced LMW neutrals (38–65%), biopolymers (7–19%), and tryptophan-like compounds (74–94%). Based on the composition characteristics of IOM, it was concluded that the molecular weight and the presence of nitrogen-containing compounds are influential parameters for determining the reactivity of IOM with ·OH.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The ·OH reactivity of IOM was determined as 4.02–7.95 × 10<SUP>8</SUP> M<SUB>C</SUB> <SUP>−1</SUP>s<SUP>−1</SUP>. </LI> <LI> IOM had 2–6 times higher ·OH reactivity than previously reported DOM. </LI> <LI> The characteristic of IOM was investigated using LC-OCD and FEEM-PARAFAC. </LI> <LI> IOM mainly consisted of low molecular weight neutrals and tryptophan-like compounds. </LI> <LI> The algae bloom could change the reactivity of DOM with ·OH. </LI> </UL> </P>

Dual-source Parallel Radiofrequency Excitation ACR Phantom Magnetic Resonance Imaging at 3 T: Assessment of the Effect of Image Quality on High-contrast Spatial Resolution, Percent Signal Ghosting, and Low-contrast Object Detectability in Comparison with

이경배,박용성,최보영 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.8

The purpose of the present study was to assess dual-source parallel radiofrequency (RF) excitationAmerican College of Radiology (ACR) phantom magnetic resonance (MR) imaging at 3Tcompared with conventional single-source RF transmission and compared with the standard ACRMRI phantom test. We used a 3T MR scanner equipped with dual-source parallel RF excitationand an 8-channel head phased array coil. We employed T1- and T2-weighted fast spin echo (FSE)pulse sequences for an assessment of the impact of image quality on high-contrast spatial resolution,percent signal ghosting and low-contrast object detectability following the ACR MRI quality control(QC) manual. With geometric accuracy and identical slice locations, dual RFs using dual-sourceparallel RF excitation MR showed an advantage over single RF using dual-source parallel RF excitationMR and conventional MR in terms of high-contrast spatial resolution (p < 0.010), percentsignal ghosting (p < 0.010), and low-contrast object detectability (p < 0.010). The quality of theimage from the dual-source parallel RF excitation MR equipment was superior to that of the imagefrom conventional MR equipment for the ACR phantom. We need to pursue dual-source parallelRF excitation MR studies involving various clinical cases.

Research on Tangential Magnetization Parallel Magnetic Path Hybrid Excitation Synchronous Machine

Pang Liang,Zhao ChaoHui,Shen HeBiao 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.5

A hybrid excitation motor with strong magnetizing ability is proposed. To solve the existing hybrid excitation machine problems, such as the diffi culty of total adjustment of air gap magnetic fi eld, many additional magnetic paths, fault tolerance is poor, and Air gap fl ux density harmonic distortion rate is high. According to the structural characteristics and the principle of magnetic regulation of tangential magnetization parallel magnetic path hybrid excitation synchronous machine. The equivalent magnetic path model of the motor was established, and the infl uence of electric excitation magnetic potential on permanent magnetic potential and air gap magnetic fi eld was analyzed. With the ANSYS Maxwell fi nite element simulation software, the variation law of the magnetic fi eld of the motor under diff erent excitation conditions is studied. The infl uence of pole boot length and magnetic pole eccentricity on air gap fl ux density amplitude and harmonic distortion rate is discussed. The results show that due to the characteristics of the parallel magnetic path. The motor has obvious eff ect of adjusting magnetic fi eld and gathering magnetic fi eld, motor fault tolerance is excellent, and less additional magnetic path. In addition, the air gap density can be optimized by using reasonable pole boot length and magnetic pole eccentricity.

전기집진기의 직렬 및 병렬식 배열에 따른 효율적인 진동 탈진에 대한 연구

최지현(Choi, Ji-Hyun),김진호(Kim, Jin-Ho) 한국산학기술학회 2013 한국산학기술학회논문지 Vol.14 No.9

전자기 진동 가진기를 적용한 전기 집진기의 효과적인 탈진 여부를 판단할 수 있는 기준은 집진기내 집진 판들의 진동 가속도이다. 이러한 진동 가속도는 외부로부터의 가진 주파수와 시스템의 고유주파수의 일치로 인하여 공진이 일어날 때 간헐적으로 최대치를 보이며 효율적인 탈진성능을 기대할 수 있다. 본 연구에서는 한대의 전자기 진동 가진기를 이용하는 단일 객체를 대상으로 한 관점에서 더 나아가, 실제 현장에서 복수의 전기집진탈진기가 설 치됨을 고려하여 진동 탈진기의 설치방식에 따라 시스템을 모델링 하였다. 이러한 직렬 및 병렬회로로 연결된 가진 기를 적용한 시스템을 대상으로 진동 가속도 계측 실험을 수행하여 직렬 및 병렬식 연결에 따른 진동 가속도의 차 이를 비교함으로써 가진기의 배열 방식과 그에 따른 기대 탈진 성능 및 소비전력의 유효성을 검증하였다. 최종적으 로 직렬 배열형 모듈이 증가할수록 선형적으로 필요전류량이 증가할 것으로 예상하였으나 급격한 감소나 (6.9% ~ 37.6%) 증가를 (5% ~ 45%) 보여주었다. 단독의 가진기가 사용된 병렬 배열보다, 2대의 가진기가 사용되고 그 전기 회로의 연결이 병렬일 때 동일한 전류가 인가되었음에도 약 11.64% 의 가속도 감소 현상을 보였다. 2대의 가진기를 사용하고 입력전류의 값을 소비 전력의 관점에서 동일하게 보정하였을 경우 약 16.80 % 의 가속도 증가 현상을 확인하였다. One of the most significant requisite that should be considered for effective rapping of the electrostatic precipitator using electromagnetic vibration exciter is vibration acceleration and resonance frequency of collecting plates. This vibration acceleration shows its peak points when natural frequencies of the system are corresponded with excitation frequency from the power source, and effective rapping performance can be expected. In this research, extend view of single electrostatic precipitator using one electromagnetic vibration exciter, the system was remodeled by arrangement of the exciters in view of multiple modules of the electrostatic precipitator in fields. And vibration acceleration measurement experiment is performed and measured values are compared with these remodeled systems. By this experimental comparison in series and parallel arrangement, effectiveness of arrangement methods for the electromagnetic vibration exciter, expected rapping performance, and power consumption are verified.

차량의 진동 테스트를 위한 다축 시뮬레이션 테이블의 기구학 해석

진재현,나홍철,전승배 제어로봇시스템학회 2011 제어로봇시스템학회 국내학술대회 논문집 Vol.2011 No.5

다양한 기원의 자연유기물질(NOM) 특성화를 위한 PARAFAC 기법 및 머신러닝의 활용

임도경,박종관 환경독성보건학회 2022 한국독성학회 심포지움 및 학술발표회 Vol.2022 No.5

용존유기물질 형광 특성 비교를 위한 PARAFAC 기법의 순차적 적용

임도경(Dokyeong Lim),최미진(Mi-Jin Choi),박종관(Jongkwan Park) 대한환경공학회 2023 대한환경공학회지 Vol.45 No.2