• Polymer(Korea)
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• v.25 no.6
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• pp.840-847
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• 2001

The crystallization characteristics of metallocene linear low density polyethylene (m-LLDPE)/linear low density polyethylene (LLDPE) blends were investigated. The effect of blending on the induction time for crystallization, spherulites growth rate, and maximum size of spherulites was mainly considered in this study. The formation of separate crystal which is well known crystallization behavior in LLDPE/LDPE blend was not found in m-LLDPE/LLDPE blends. The blending m-LLDPE to LLDPE caused the dramatic decrease in the induction time of m-LLDPE/LLDPE blends but it seems that the blend composition shows less effect on the induction time. Lower branching number in m-LLDPE resulted in the increasing of spherulites growth rate and the maximum size of spherulites is depend upon both the induction time and spherulites growth rate of LLDPE component affected by m-LLDPE.

• Korean Journal of Plant Tissue Culture
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• v.28 no.3
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• pp.129-134
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• 2001

Winter bud explants from 15 individual angelica tree (Aralia elata) were cultured in vitro to find out optimal conditions for somatic embryo induction as well as plant regeneration. Calli are induced and grown on MS medium supplemented with 1.0 mg/L 2,4-D for 4 weeks and subcultured on a half-strength MS medium without phytohormones to induce somatic embryos. Inter-simple sequence repeat (I-SSR) markers were analyzed with total DNAs extracted from the trees. Genotype effects on somatic embryo induction were examined by cluster analysis. Callus induction rate varied from 58.5 to 100% among the genotypes. Somatic embryo induction rate also greatly varied from 0 to 100% among the genotypes. There was a significant difference in somatic embryo induction rate even among the individual trees that showed close genetic relationships each other. This suggested that somatic embryo induction rate in Aralia elata be influenced by a few major specific genes rather than whole genomic similarity among individual trees. Four individuals of Ulneong-7, Cheju-1, Shingu and China, which are recalcitrant to somatic embryo induction, turned out to have a close genetic relationship, suggesting that both physiological and genetic factors affect somatic embryo induction. The results suggest that genotype selection be the most important factor to achieve an efficient propagation, although cultural optimization through medium and explant manipulation may also play crucial roles in somatic embryogensis as well as plant regeneration of these species.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.6
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• pp.533-539
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• 2008

An high frequency induction hardening technology of vehicle body press-formed of thin sheet steel has been developed to increase the strength of vehicle body parts locally by high frequency induction heating, thereby eliminating the need for reinforcements. And this technique for increasing the tensile strength of sheet steel was practically applied to the front floor cross member and center pillar reinforcement of a passenger car. The side impact behavior has been investigated when induction hardening technology is applied to the conventional low-carbon steel and weight reduction of an automotive body is expected. In this paper, basic experiments were performed for the hat-shaped specimen under high frequency induction heating process. Martensitic transformation was found in the heating zone through microscopic observation which showed higher hardness. In addition, the hardness and strength of the center-pillar specimen made of boron steel increased remarkably by high frequency induction heating.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1119-1123
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• 2008

High-frequency induction is an efficient way to heat mold surface by electromagnetic induction in a noncontact procedure. It has been recently applied to the injection molding of thin-walled parts or micro/nano structures. Though the induction heating has an advantage in terms of its rapid-heating capacity on the mold surface, it still has difficulty in efficient mold temperature control due to the restriction of an induction coil design suitable for the given mold shape. The present study proposed a localized mold heating method by means of selective use of mold material. For localized induction heating, an injection mold composed of ferromagnetic material and paramagnetic material is used. The electromagnetic induction concentrates on the ferromagnetic material, from which we can selectively heat for the local mold elements. The feasibility of the proposed heating method is investigated through an experimental measurement in terms of the heating efficiency on the localized mold surface.

• Journal of electromagnetic engineering and science
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• v.10 no.4
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• pp.276-281
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• 2010

In this paper, an electromagnetic induction on a telecommunication line by the distribution line of a power provision system or a feeder line of an electrified railway system has been verified through experiments. The basic cause of induction occurrence by these practical power provision systems is the returning current through the earth. This principle has been confirmed by the experiments documented in this paper which implemented these mechanisms to incur an induction. Experimental methods were used to produce the returning current through the earth. The experiment to find a relationship between inducing strength and the distance between the two phase lines in a power provision line has also been included to confirm that, when the distance is enlarged, the induction effect increases as the cross-nullification effect of magnetic fluxes decreases. An experiment for the existence of a shielding effect by another conduction length material has been addedas a protection measure against the induction.

• Journal of Microbiology and Biotechnology
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• v.5 no.4
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• pp.224-228
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• 1995

Fed-batch fermentations were conducted to produce human lipocortin-I (LC1), a potential anti-inflammatory agent, from recombinant Sacchromyces cerevisiae carrying a galactose-inducible expression system. The cell growth, expression level of LC1, and the plasmid stability were investigated under various LC1 induction modes performed by three different galactose feeding strategies. Galactoe was fed to induce the expression of LCl from the beginning (initial induction) of culture or when the cell concentration reached 120 OD (mid-phase induction) or 300 OD (late induction). Among the three galactose-induction modes tested, the initial induction mode yielded the best result with respect to a final expression level of LC1. Fedbatch fermentation with initial induction mode produced LC1 at a conentration of 220 mg/l, which corresponded to 1.38- and 1.53-fold increases over those produced by mid-phase and late induction modes.

• Journal of Adhesion and Interface
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• v.19 no.4
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• pp.167-172
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• 2018

In this study, a polyurethane hot melt adhesive was synthesized and metal particles sensitive to induction heating were added to produce an induction heating melt adhesive. The thermal behavior and adhesion characteristics of metal particles were investigated according to the kind, size and induction heating conditions. Among the various metal particles, induction heating efficiency was the best when nickel and iron were applied. Induction heating efficiency increased with decreasing metal particle size. In addition, the strength of the induction heating power of the adhesive was high and the adhesive strength was improved as the adhesive thickness was thinner.

• Nuclear Engineering and Technology
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• v.55 no.10
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• pp.3571-3580
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• 2023

The application of the induction bending process to pipe systems in various industrial fields is increasing. Recently, efforts have also been made to apply this bending process to nuclear power plants because it can innovatively reduce welded parts of the curved pipes, such as elbows. However, there have been no cases of the application of induction bending to the piping of nuclear power plants. In this study, the applicability of the P91 induction bending piping for the sodium-cooled fast reactor PGSFR was validated through high temperature low cycle fatigue tests and creep tests using P91 induction bending pipe specimens. The tests confirmed that the materials sufficiently satisfied the fatigue life and the creep rupture life requirements for P91 steel at 550 ℃ in the ASME B&PV Code, Sec. III, Div. 5. The results show that the effects of heating and bending by the induction bending process on the material properties were not significant and the induction bending process could be applicable to piping system of PGSFR well.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.4
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• pp.812-818
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• 2003

This paper presents a developed outside rotor type induction motor for the fan. Nearly all of the induction motors consist of two parts, rotor and stator, and the position of rotor is generally inside of stator. However, the rotor of the developed induction motor is located outside of stator. It is believed that the outside rotor type induction motor is suitable for the fan due to its large inertia, that is, it is considered that the change of air flow rate resulting from input power or load fluctuation is reduced. In this paper, the two tests which are suitable to obtain the electrical parameters of the outside rotor type induction motor were described, then various parameters of outside rotor type induction motor were measured. These are the locked rotor test and no load test. By using these tests, it was possible to determine the parameters which are presented in the steady-state equivalent-circuit of the outside rotor type induction motor. Load test of induction motor was carried out using a dynamometer and the torque-speed curve was obtained. It is believed that the results of this paper can be used for the development of the outside rotor type induction motor.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.10
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• pp.82-93
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• 2006

In this paper, filters are designed to reduce transients overvoltage in inverter fed high-voltage large-capacity induction motor drive system. Design issues for a LCR filter at the inverter output terminals to reduce the dv/dt of the inverter output pulse and a RC filter at the induction motor input terminals to match the characteristic impedance between cable and induction motor are examined in detail. These filters are modeled to be suitable to high-voltage large-capacity induction motor. The performance of the filter is evaluated through simulation using EMTP(ElectroMagnetic Transients Program). We presented filters that used high voltage large-capacity induction Motor on the basis of this. Effect of the filter is analyzed for variation of the cable length. Characteristics of filters are analyzed to reduce harmonic in voltage waveform of induction motor input terminal. The switching surge voltage became the major cause to occur the insulation failure by serious voltage stress in the stator winding of induction motor. Filter for to mitigate transients overvoltage presents a required component in drive system of high-voltage large-capacity induction motor. Also, proposed filters are proved through simulation using EMTP.