• Progress in Superconductivity and Cryogenics
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• v.11 no.4
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• pp.33-36
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• 2009

An air gap between the pancake windings was provided in this paper to increase the central magnetic field of a high temperature superconducting (HTS) magnet consisting of pancake windings. Unlike the LTS magnet, providing an air gap between the pancake windings increases the central magnetic field of a HTS magnet. Furthermore, the uniformity of the magnetic field near the center of the magnet increased because the pancake windings spread out in wider area. Effects of the air gap on the central magnetic field of an HTS magnet was described in this paper, Calculation of the critical current was carried out by using E-J relation of the HTS wire and the optimization technique was adopted to obtain the appropriate critical current which could maximize the central magnetic field. Pancake windings with BSCCO-2223 HTS wire were wound on glass epoxy bobbin. 6 double pancake windings with 200 turns were used to construct a HTS magnet. Characteristics of the HTS magnet including the central magnetic field and the uniformity of the magnetic field were measured and compared with the results of calculation.

• Progress in Superconductivity and Cryogenics
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• v.9 no.3
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• pp.32-36
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• 2007

On the contrary of a conventional motor with very narrow air-gap. it is difficult to calculate the accurate magnetic field distribution and the performance of an air-cored superconducting motor by 2 dimensional analysis. which does not use high permeability material except outer machine shield. This paper aims to do analysis of magnetic field and force distribution from the 3 dimensional modelling of a 1MW class superconducting synchronous motor. Especially. the field coil composed of Bi-2223 high-temperature superconductor and the outer machine shield are modelled by finite element analysis software according to their structures and the self-inductance and Lorentz force are calculated based on the 3 dimensional magnetic field calculation. Moreover. the influence of an important parameter, synchronous reactance, has been analyzed on the machine performances such as voltage variation and output power.

• Progress in Superconductivity and Cryogenics
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• v.10 no.3
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• pp.23-26
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• 2008

Constructions of coated conductor which is differently from Bi-2223 is comprised multiple coatings on a base material or substrate and designed to achieve the highest degree of alignment possibility of the atoms in the superconductor material. In this study, we are measured and analyzed degradations of critical current according to diameter. In addition to study the effects of bending strain, we observed the AC loss of coated conductor and carried out analytical study for relation between Ic degradation and AC loss as well. The measurement of AC loss and numerical calculation was carried out based on Norris theory to compare with experimental results. The relationship between critical current and AC loss of HTS tapes with partial deformation by mechanical stress was studied. These results will amount the most important basis data in the of HTS cable, magnet, etc that winding work is required.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.943-945
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• 2002

This paper presents conceptual design and 3-D electromagnetic analysis of 1MVA transformer with BSCCO-2223 High Tc Superconducting (HTS) tapes. The rated voltages of each sides of the transformer are 22.9 kV and 6.6 kV, and double pancake windings were adopted. High voltage and Low voltage sides were composed of several double pancake windings. Four HTS tapes were wound in parallel for the windings of low voltage side and were transposed in order to distribute the currents equally in each conductor. The transformer core was designed as a shell type core made of laminated silicon steel plates and the core is separated with the windings by a cryostat with Fiberglass Reinforced Plastics(FRP). A sub-cooling system using $LN_2$ were designed to maintain the coolant temperature of 65K. Finally perpendicular components of magnetic field applied to tapes were calculated 0.24T in the rated operation using 3-D analysis. A real 1MVA HTS transformer will be manufactured in near future based on the design parameters presented in this paper.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.342-343
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• 2009

Paper factories use a large amount of water and same amount of wastewater is generated. It is important to purity and recycle the wastewater because of water shortages and water pollution. The existing water treatment facilities like precipitation process need large-scale equipment and wide space to purity the wastewater of paper factory. High gradient magnetic separation (HGMS) system has the merits to purity rapidly because of large voids at filter and to occupy small space. In this paper, two types of superconducting magnets were used for HGMS systems. Cryo-cooled Bi-2223 superconducting magnet system with 70 mm room temperature bore and 200 mm of height was prepared. Cryo-cooled Nb-Ti superconducting magnet with 100 mm room temperature bore and 600 mm of height was used for magnetic separator. Magnetic filters were designed by the analysis of magnetic field distribution at superconducting magnets. The various magnetic seeding reactions were investigated to increase the reactivity of coagulation. The effects of magnetic separation of wastewater were investigated as variation of magnetic field strength and flow rate of wastewater.

• Progress in Superconductivity and Cryogenics
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• v.5 no.3
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• pp.34-37
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• 2003

A 1 MVA single-phase high temperature superconducting (HTS) transformer with BSCCO-2223 wire was designed in this paper. The rated voltages of each sides of the transformer are 22.9 kV and 6.6 kV respectively. Double pancake HTS windings arranged reciprocally will be used for the transformer windings, because of the advantages of insulation and distribution of surge voltage in case of a large power and high voltage transformer. Single HTS wire was used for the primary windings and four parallel wires were used for the secondary windings of the transformer with transposition. A core of the transformer was designed as a shell type core separated with the windings by a cryostat made of GFRP with a room temperature bore. The operating temperature of the HTS windings will be about 65K with sub-cooled liquid nitrogen. A cryogenic cooling system using a GM-cryocooler for this HTS transformer by natural convection of liquid nitrogen was designed. This type of cooling system can be a good option for compactness, efficiency, and reliability of the HTS transformer.

• Journal of Microbiology and Biotechnology
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• v.18 no.9
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• pp.1584-1589
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• 2008

Although resistance of Helicobacter pylori to clarithromycin is a major cause of failure of eradication therapies, little information is available regarding gene mutations of clarithromycin-resistant primary and secondary H. pylori isolates in Korea. In the present study, we examined gene mutations of H. pylori 238 rRNA responsible for resistance to clarithromycin. DNA sequences of the 238 rRNA gene in 21 primary clarithromycin-resistant and 64 secondary clarithromycin-resistant strains were determined by PCR amplification and nucleotide sequence analyses. Two mutations of the 238 rRNA gene, A2143G and T2182C, were observed in primary clarithromycin-resistant isolates. In secondary isolates, dual mutation of A2143G+T2182C was frequently observed. In addition, A2143G+T2182C+ T2190C, A2143G+T2182C+C2195T, and A2143G+T2182C+A2223G were observed in secondary isolates. Furthermore, macrolide binding was tested on purified ribosomes isolated from T2182C or A2143C mutant strains with $[^{14}C]$erythromycin. Erythromycin binding increased in a dose-dependent manner for the susceptible strain but not for the mutant strains. These results indicate that secondary isolates show a greater variety of 238 rRNA gene mutation types than primary isolates, and triple mutations of secondary isolates are associated with A2143G+T2182C in H. pylori isolated from Korean patients.

• Journal of Food Hygiene and Safety
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• v.19 no.3
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• pp.132-139
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• 2004

As measure against the environmental pollution, maximum efforts to improve of the environmental pollution have also been made; removal of the contaminated sediments of the bay and the coastal area, monitoring of several heavy metal levels in fishes, shell fishes, sea water and sediment, and so on. The objective of this research is to investigate how much metals are included in the sea water, sediment, fishes and shell fishes in kyeongnam coastal area. Specifically, we are investigating the relationships between the metal included in fishes and sea water, and shell fishes and sediment, and heavy metals and heavy metals respectively. Heavy metal over the studied component and area, the average concentrations of Pb, Cd, Cr and Hg in sea water were 0.0029 mg/L, 0.005 mg/L, 0.0016 mg/L and ND, those of sediment were 11.9583 mg/kg, 0.2136 mg/kg, 1.9158 mg/kg and Hg 0.0108 mg/kg, those of fishes were 0.4358 mg/kg. 0.0726 mg/kg, 1.1188 mg/kg and Hg 0.0622 mg/kg, and those of shellfishes were Pb 0.6738 mg/kg, Cd 0.2223 mg/kg, Cr 0.5516 mg/kg and Hg 0.0117 mg/kg respectively. In the relationship test, Cd was significant in the relationship between fishes and sea water, and Hg was significant in the relationship between sediment and shellfishes.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.300-304
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• 1999

To tap the feasibility of exploiting the 2$^{nd}$ phases as flux-pinning centers in the (Bi,Pb)$_2Sr_2Ca_2CuO_{10}$ superconductor, the size and the distribution of the precipitates have been controlled by changing reaction temperature and time, oxygen partial pressure Po$_2$ and annealing condition. Various annealing heat treatments were also conducted on the as-received 61 filament Bi-2223 tapes with Bi$_{1.8}Pb_{0.4}Sr_2Ca_{2.2}Cu_3O_8$ starting composition and annealed specimen were analyzed with XRD, SEM, EDS and TEM.. The grain size of (Ca,Sr)$_2$(BiPb)O$_4$ or Bi$_{0.5}Pb_3Sr_2Ca_2CuO_{\delta}$ was controllable by optimizing the heat treatment condition and critical current density (J$_c$) showed dependence on the size of the 2$^{nd}$ phases.

• Journal of the Ergonomics Society of Korea
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• v.5 no.1
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• pp.19-28
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• 1986

To study the body trunk form which is essential to clothing constructions, necessary body sizes were measured indirect1y from 216 unmarried women from 19 to 24 years old by a photographic network method. The results are obtained as follow; 1) In this study of body type measurements, the four factors of bust, abdomen, column and hip size have been divided into four-stage intervals and given the body type codes 1, 2, 3 and 4, with 1 designating the size difference of the factor with the minimum size difference of the factor with the maximum size difference from waist size. These body type codes can be easily, linguistically interpreted. In this study, among $4^4=256$ possible body types, 54 types appeared frequently. These 54 types are integrated into 6 groups of types by clustering analysis. Representative types of each group are types 3333 and 2333 in group 1, 2233, 1233 and 1332 in group 2, 2222, 1222 and 1223 in group 3, 2223 in group 4, 2323 and 2322 in group 5, and 3323, 3223 and 3322 in group 6. In the types of groups 1, 2, and 3, the change is mainly in bust size, and in the types of group 4. is single type. In the types of group 5 the change is mainly in hip size, and in the types by groups 6 the change is mainly in abdomen size and hip size. 2) The analysis by measuring the four elements of body trunk in reference to waist size is scientific and grading of similar styles is possible in clothing construction. 3) Assuming that the human body is oval, using the calculating method, the size of girth, which cannot be measured by the indirect measuring method, is obtained approximate to actual size, with an error of ${\pm}2.8cm$.