• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2002년도 추계학술발표회
• /
• pp.122-124
• /
• 2002

The removal capacity of zero-valent iron for Cr(Ⅵ) was evaluated using batch kinetic tests. The rate constants for zero-valent iron dramatically increased as initial Cr(Ⅵ) concentration decreased. Generally, the reaction rates of Cr(Ⅵ) with zero-valent iron were faster than that of a biotic degradation of Cr(Ⅵ), and furthermore the reaction rates were inversely proportional to the initial Cr(Ⅵ) concentrations. After certain reaction time elapsed. no further decrease of Cr(Ⅵ) was observed, indicating a loss of iron reactivity. The loss of iron reactivity was primarily due to the passivation of iron surfaces with iron-Cr precipitates, but the reactivity of iron was recovered by adding iron-reducing bacteria. Even though the addition of bacteria itself removed Cr(Ⅵ), the combination of iron-reducing bactera and oxidized iron significantly enhanced the reaction rate for Cr(Ⅵ) removal. The results from column tests also confirmed that the innoculation of iron-reducing bacteria to the column containing completely oxidized iron partially enhanced the recovery of the iron reactivity.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2002년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.91-93
• /
• 2002

This paper presents a calculation method of iron loss in Induction Motor which is based on 2D Transient Finite Element Method. Iron loss is evaluated by the frequency analysis of flux density waveforms using Discrete Fourier Transforms (DFT) and iron loss curves data. Then. the distribution of loss and the total loss are obtained. The validity of this method is verified by the comparison of the estimated values with measured ones.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• 제9권2호
• /
• pp.129-138
• /
• 2006

Lots of cases relating Helicobacter pylori infection to iron-deficiency anemia have been described in the literature and H. pylori infection has emerged as a cause of refractory iron-deficiency anemia which is unresponsive to oral iron therapy. H. pylori-associated iron-deficiency anemia can be treated by H. pylori eradication. It is not thought to be attributable to gastrointestinal blood loss, such as duodenal ulcer. The mechanism by which H. pylori infection contributes to iron-deficiency anemia remains unclear. However, four possible explanations can be posited for this relationship; occult blood loss secondary to chronic gastritis, reduced iron absorption due to hypo- or achlorhydria, increased iron consumption by H. pylori, and iron sequestration in gastric mucosa. H. pylori-associated iron-deficiency anemia seems to develop in populations at increased risk for iron depletion. When pubescent girls, including athletes, are found to have iron-deficiency anemia refractory to iron administration, they should be evaluated for H. pylori infection.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.128-130
• /
• 2003

For electrical machine designers, core loss data are usually provided in the form of tables or curves of total loss versus flux density or frequency. The aim of this work is to propose a mathematical model for the iron losses prediction in soft magnetic material$ with any frequency and flux density. In this paper, three formulas for calculating the iron loss coefficients are discussed. And the coefficients are applied to calculate the iron loss of the 25kW high speed motor.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2002년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.138-140
• /
• 2002

This paper deals with an automatic design procedure for the minimization of iron core loss in a synchronous reluctance motor (SynRM). The focus of this paper is the design relative to hysteresis loss on the basis of rotor shape of a SynRM in the same torque density. The coupled Finite Elements Analysis (FEA) & Preisach model have been used to evaluate the iron core loss with the rotor shape. The proposed procedure allows to define the rotor geometric dimensions starting from an existing motor or a preliminary design. The iron loss has been reduced with a rotor design variation.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2009년도 제40회 하계학술대회
• /
• pp.758_759
• /
• 2009

In the design and analysis of electric machines the precise calculation of iron loss has incredible significance. It is tough to foresee iron losses precisely in machines due to distribution of non sinusoidal flux density. It is necessary to approximate the iron losses for the precise computation of efficiency. This paper presents a novel approach for the prediction of iron losses of the brushless dc (BLDC) motors by considering the effects of minor hysteresis loops in the simplified model. The novel iron loss model results are compared with the simplified model and with finite element method (FEM).

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 제39회 하계학술대회
• /
• pp.723-724
• /
• 2008

The rotational loss is one of the most important problems for the practical applications of PM synchronous motor/generator. This rotational loss is divided as the mechanical loss by windage and bearing and iron loss by hysteresis loop and eddy current in the part of the magnetic field. So, In this paper, a double-sided PMSM/G without the iron loss is designed by analytical method of the magnetic field and estimation of the back-EMF constant represented as the design parameter. This design model consists of the double-sided PM rotor with Halbach magnetized array and coreless 3-phase winding stator. The results show that the double-sided PMSM/G without iron loss can be applicable to the required system without the rotational loss.

• Journal of Magnetics
• /
• 제18권3호
• /
• pp.268-275
• /
• 2013

This paper shows the characteristics of performance for interior permanent magnet machine (IPM) considering driving conditions such as maximum torque per ampere (MTPA) and flux-weakening control especially in terms of harmonic loss. In particular, based on finite element analysis (FEA), permanent magnet (PM) eddycurrent loss and the harmonic iron loss have been computed where the models have been intentionally designed to identify the effects of pole-slot combinations on the loss while maintaining the required power for electric vehicle. From the analysis results, it was shown that the rotor iron loss and PM eddy-current loss of machine employing fractional slot winding are extremely large at load condition. Furthermore, it was revealed that the harmonic iron loss at high-speed operation is mainly distributed over stator teeth and rotor surface, which may aggravate cooling system of the rotor structure in the vehicle.

• 대한지역사회영양학회지
• /
• 제3권1호
• /
• pp.12-20
• /
• 1998

In this study, the food intake, feces and urine of 14 primary school age boys and girls were collected and intake and excretion of iron and zinc were measured. The boys and girls were 8-12 years old and measurement continued for four weeks during which they maintained their normal living pattern. Each boy's and girl's daily intake and excretion of iron and zinc were measured and apparent digestibility and balance were also calculated. The results are as follows. Mean daily intake of iron was $14.9\pm{0.6mg}$ for the boys and $12.4\pm{0.5mg}$ for the girls. Mean daily intake of zinc was $11.8\pm{1.2mg}$ for the boys and $11.5\pm{0.4mg}$ for the girls. Mean daily fecal loss and apparent digestibility of iron was $6.1\pm{0.3mg}$ and $58.8\pm{2.0%}$ for the boys and $6.8\pm{0.1mg}$ and $44.1\pm{2.0%}$ for the girls. Mean daily fecal loss and apparent digestibility of zinc was $9.3\pm{0.2mg}$ and $14.4\pm{5.1%}$ for the boys and $9.7\pm{0.4mg}$ and $14.3\pm{4.3%}$ for the girls. Mean daily urinary loss of iron was $1.1\pm{0.1mg}$ and showed the positive balance of $7.86\pm{0.6mg}$ for the boys and $0.5\pm{0.1mg}$ and showed the positive balance of $5.14\pm{0.4mg}$ for the girls. Mean daily urinary loss of zinc was $0.5\pm{0.1mg}$ and showed the positive balance of $1.03\pm{0.6mg}$ for the girls.

• 전기학회논문지
• /
• 제63권11호
• /
• pp.1575-1581
• /
• 2014

In this paper, eddy current loss, iron loss and heat transfer of PMSG with 2,000kW capacities were analyzed for wind turbine. The PMSG with 3 split magnet was analyzed using ansoft maxwell commercial program and, generator was tested by Back to Back converter with no load condition at laboratory. Rotor surface temperature was measured by Pt100 sensors for investigating heat transfer from rotor to atmosphere. The simulation results shows 27.4kW eddy current loss in no load condition and 50.2kW eddy current loss in rated load condition with 3 split magnet, and also shows 4.3kW iron loss in no load condition and 7.3kW iron loss rated load condition. The heat transfer coefficient of convection between rotor surface and atmosphere was investigated by $9.6W/m^2{\cdot}K$. Therefore the heat transfer from rotor to atmosphere was about 17kW(54%) and from rotor to air-gap was about 14.6kW(46%) in no load condition. It is identified that the cooling system for stator have to include the 46% of iron loss, and heat dissipation structure of rotor surface have to be suggested and designed for efficiency improvement of generator.