• Journal of Magnetics
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• v.22 no.2
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• pp.306-314
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• 2017

Nowadays power quality effects on induction motors have gained significant attention due to wide application of these motors in industry. The impact of grid voltage fluctuations on the induction motor behavior is one of the important issues to be studied by power engineers. The degree of iron saturation is a paramount factor affecting induction motors performance. This paper investigates the effects of voltage fluctuations on motor magnetic saturation based on the harmonic content of airgap flux density by finite element method (FEM). It is clarified that the saturation harmonics under normal range of voltage fluctuations have not changed significantly with respect to pure sinusoidal conditions. Experimental results on a 1.1 kW, 380 V, 50 Hz, 2 pole induction motor are employed to validate the accuracy of the simulation results.

• Resources Recycling
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• v.11 no.5
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• pp.7-10
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• 2002

Iron nitride magnetic fluid was oxidized by exposing it to the air under normal atmospheric conditions. After exposure of 3.2 hours, the relative saturation magnetization of the iron nitride magnetic fluid is less than 0.4 compared to the value of the unexposed sample, and it is nearly zero after exposure for 1008 hours. The structure of the oxidized iron nitride is considered to be a non-magnetic hematites. The thickness of the oxidation layers of the iron-nitride particles are nearly the same, about 3 nm, regardless of the different particle sizes.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.4
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• pp.490-500
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• 1996

The conventional method to deal with current transformer (CT) Saturation is over dimensioning of the core so that CTs can carry up to 20 times the rated current without exceeding 10% ratio correction. However, this not only reduces the sensitivity of relays as some errors may still be present in the secondary current when a severe fault occurs, but also increases the CT size. This paper presents an algorithm for compensating the distorted secondary current of iron-cored CTs under CT saturation using the magnetization (flux-current : .lambda.-i) curve and its performance is examined for fault currents encountered on a typical 345[kV] Korean transmission system, under a variety of different system and fault conditions. In addition, the results of hardware implementation of the algorithm using a TMS320C10 digital signal processor are also presented. The proposed algorithm can improve the sensitivity of relays to low level internal faults, maximize the stability of relays for external faults, and reduce the required CT core cross-section significantly. (author). refs., figs.

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.93.2-93.2
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• 2008

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2001.02a
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• pp.98-101
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• 2001

This work presents racetrack High Temperature Superconducting (HTS) magnet with iron plates to achieve the maximum current-carrying capacity and the simple shape that can easily be wound and jointed. The shape, position and kinds of iron plates are chosen by using 3 Dimensional Finite Element Analysis (3d FEA) considering magnetic saturation of iron plates. The racetrack HTS magnet with iron plates, magnet having optimized current distribution and initial magnet are compared with each other through 3D FEA, manufacturing and testing these magnets. The measured performance of the magnet with iron plates improved by 50% on the basis of initial magnet.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.124-127
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• 1997

The magnetic properties of calcined Sr-ferrites, related to the iron oxides, produced from three different process in steel plants, have been investigated. The powder f.characteristics of iron oxides are much affected on the magnetic properties of calcined Sr-ferrite Powders. It was possible to improve the magnetic property of calcined Sr-ferrites with the iron oxide powders of small size and narrow size distribution. The maximum magnetic properties of calcined Sr-ferrites, showing 69 emu/g of saturation magnetization and 4020 Oe of intrinsic coercivity, are achieved at the following conditions; the iron oxides from the chemirite process(EP), mole ratio of 5.8, and calcination condition of 120$0^{\circ}C$/1hr.

• Journal of the East Asian Society of Dietary Life
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• v.22 no.4
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• pp.463-472
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• 2012

This study was performed to investigate the iron status and its related factors in female college students residing in Gyeongnam. The prevalence of iron deficiency among subjects ranged from 3.4% in mean corpuscular hemoglobin concentration (MCHC) to 43.7% in ferritin. Weight, lean body mass (LBM) and body mass index (BMI) were positively correlated with ferritin concentration, but negatively correlated with total iron binding capacity (TIBC). Among the nutrients, vitamin A and B2 were major predictors of elevated iron status. Meal regularity was positively correlated with Fe and ferritin concentration, and meal number with transferrin saturation (TS), meal quantity with red blood cell (RBC) and hematocrit (Hct). Consumption of fruit, meat, fish and poultry showed strong positive correlation with hematological indices. Therefore, increasing vitamin A, B2, C, and iron intakes as well as maintenance of a healthy weight may be helpful in preventing iron deficiency in female college students.

• Archives of Pharmacal Research
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• v.26 no.10
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• pp.874-879
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• 2003

The present study was carried out to examine the stability of microencapsulated ascorbic acid in simulated-gastric and intestinal situation in vitro and the effect of microencapsulated ascorbic acid on iron bioavailability. Coating materials used were polyglycerol monostearate (PGMS) and medium-chain triacylglycerol (MCT), and core materials were L-ascorbic acid and ferric ammonium sulfate. When ascorbic acid was microencapsulated by MCT, the release of ascorbic acid was 6.3％ at pH 5 and 1.32％ at pH 2 in simulated-gastric fluids during 60 min. When ascorbic acid was microencapsulated by PGMS, the more ascorbic acid was released in the range of 9.5 to 16.0％. Comparatively, ascorbic acid release increased significantly as 94.7％ and 83.8％ coated by MCT and PGMS, respectively, for 60 min incubation in simulated-intestinal fluid. In the subsequent study, we tested whether ascorbic acid enhanced the iron bioavailability or not. In results, serum iron content and transferring saturation increased dramatically when subjects consumed milks containing both encapsulated iron and encapsulated ascorbic acid, compared with those when consumed uncapsulated iron or encapsulated iron without ascorbic acid. Therefore, the present data indicated that microencapsulated ascorbic acid with both PGMS and MCT were effective means for fortifying ascorbic acid into milk and for enhancing the iron bioavailability.

• Journal of Community Nutrition
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• v.1 no.2
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• pp.140-147
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• 1999

It has been known for some time that elevated body iron could be a risk factor for coronary heart disease. The present study was conducted to determine body iron status and dietary iron intake of patients with myocardial infarction(MI). Seventy five patients from the Chunam area with their first MI history within he past 2 months were recruited. The serum iron concentration, total iron binding capacity(TIBC) and percent transferrin saturation(TS) were selected as indicators of body iron status. Twenty four hour recall was conducted by trained interviewers to asses the dietary intake. Most women (91.3%) showed waist to hip ratio(W/H) greater than 0.85 while 17.3% of men were assessed to have a tendency of abdominal obesity(W/H>0.95). The average BMI of women was 25.80 and that of men was 23.98. The average diet intake of participants was below the recommended dietary allowances (RDA) for most nutrients. He average dietary iron intake was 10.03 mg/day for all subjects while women's iron intake was significantly lower than men's. However, a great proportion of participants (77%) showed a tendency to have normal iron status. About 9% of the participants were assessed as iron deficient and 14% had an iron overload. The mean serum iron concentration was 125 g/dl ranging from 13.3 to 280.6 g/dl. Iron intake from animal sources were significantly associated with body iron status (r=0.257, p=0.026) when TIBC was used as an iron status indicator. When iron status was assessed with TS, it was directly associated with iron intake from animal sources(r=0.278, p=0.05) for he subjects in the normal iron status group. He results of the present study showed that the nutrient intake of Mi patients in Chunan was not quite adequate while iron status was mostly in the normal range. Further studies are needed to investigated whether there is a possible difference in iron metabolism of the MI patients.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.14-15
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• 2006

A saturation of magnetic flux in the core may occur when a large primary current flows when the iron-cored current transformer is used. This saturation makes the distorted secondary current of the CT. the distorted secondary current may cause the mal-operation or operation time delay of protective relays. CT compensation algorithm using The LSQ(Least Square) fitting method has a problem. It needs to acquire enough data for executing this algorithm without an error. In this paper, an enhanced algorithm using interpolation based LSQ(Least Square) Fitting Method is proposed. The Lagrange Interpolation Method is used for the interpolation and CT is simulated by EMTP. The results show that the proposed algorithm can accurately compensate a distorted secondary current more than existing Algorithm when the saturation severely occurs.