• Electrical & Electronic Materials
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• v.10 no.2
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• pp.97-104
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• 1997

In this paper, in order to investigate the behavior of charged particles on (Sr.Ca)TiO$_{3}$ ceramics with paraelectric properties, the characteristics of electrical conduction and thermally stimulated current was measured respectively. As a result, the conduction mechanism is divided into three regions having different mechanism as the current increased. The region I below 200[V/Cm] shows the ohmic conduction. The region B between 200[V/cm] and 2000[V/cm] can be explained by the Poole-Frenkel emission theory, and the region III above 2000[V/cm] is dominated by the tunneling effect. The three peaks of TSC were obtained at the temperature of -20[.deg. C], 20[.deg. C] and 80[.deg. C], respectively. The origins of these peaks are that the .alpha. peak observed at -20[.deg. C] looks like to be ascribed to the ionization excitation from donor level in the grain, and the .alpha.' peak observed at 20 [.deg. C] appears to show up by hopping conduction of the trapped carrier of border between the oxidation layer and the grain, and the .betha. peak observed at 80[.deg. C] seems to be resulted from hopping conduction of existing carrier in the trap site of the border between the oxidation and second phase.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.226-227
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• 2006

The conduction-cooled HTS SMES is operated in cryogenic and high vacuum condition. Thus, Insulation design at cryogenic temperature and high vacuum is a key and an important element that should be established to accomplish miniaturization that is a big advantage of HTS SMES. Therefore, we need active research and development of insulation concerning application of the conduction-cooled HTS SMES. Therefore, in this study, we experimented about insulation characteristic high vacuum and cryogenic similar to driving condition of SMES system. Also, investigated about insulation characteristic of suitable some materials to insulator for conduction-cooled HTS SMES. As this results, we possessed basis data for insulation materials selection and insulation design for development of 600 kJ class conduction-cooled HTS SMES.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.7
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• pp.602-605
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• 2009

The heat generation in the high-$T_c$ superconducting (HTS) wire is related with the cost efficiency and safe factor of HTS devices. This paper deals with the thermal quench at the conduction-cooled joint between HTS wire and copper terminals. The 3-D numerical simulation of thermal distributions in part of the copper terminals was implemented and the premature quench at copper block was observed through the test. The results will be helpful to design the conduction-cooled HTS magnets.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2310-2318
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• 2018

Critical conduction mode (CRM) operation is more efficient than continuous conduction mode (CCM) operation at low power levels because of the valley switching of switches and elimination of the reverse recovery losses of boost diodes. When using a sensorless digital control method, an error occurs between the actual and the estimated current. Because of the error, it operates as CCM or discontinuous conduction mode (DCM) during CRM operation and also has an adverse effect on THD of input current. In this paper, a current sensorless technique is presented in an inverter system using a bridgeless boosted power factor correction converter, and a compensation method is proposed to reduce CRM calculation error. The validity of the proposed method is verified by simulation and experiment.

• Electrical & Electronic Materials
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• v.9 no.8
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• pp.776-782
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• 1996

The electrical properties of vapor deposition polymerized polymide thin films for getting an in-line system with manufacturing process of semiconductor device, have been studied. Polyimide thin films fabricated by vapor deposition polymerization(VDP) method based on PMDA and 4,4'-DDE monomer were confirmed by FT-IR spectra. It is found that the major conduction carriers of thin films are ions, and the hopping length of ions is almost same with monomer length at the temperature over 120.deg. C through the analysis of electrical conduction mechanism. Also, The activation energy is about 0.69 eV at the temperature of >$30^{\circ}C$ - >$150^{\circ}C$ and it is shown that the resistivity at which thin films can be used as an insulating film between layers of semiconductor device, is 3.2*10$^{15}$ .ohm.cm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.197-200
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• 2005

We have studied conduction mechanism that is interpreted in terms of space charge limited current (SCLC) region and tunneling region. The OLEDs are based on the molecular compounds, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD) as a hole transport, tris (8-hydroxyquinolinoline) aluminum(III) $(Alq_3)$ as an electron injection and transport and emitting layer. We manufactured reference structure that has in $ITO/TPD/Alq_3/Al$. Buffer layer effects were compared to reference structure. And we have analyzed out electrical conduction mechanism in $ITO/Alq_3/Al$ device with various temperature.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.1993-1998
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• 1997

This paper presentes a novel single-phase unity power factor rectifer, which features Critical Conduction Mode and ZVS. The reduced conduction losses are achieved by the employment of a single converter instead of the typical configuration composed of a front end rectifier followed by a boost converter. Theoretical analysis, a design example and experimental results of a 300 converter with $127V_{rms}$ input voltage and 400 VDC output voltage are presented.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1991.10a
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• pp.64-68
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• 1991

It happened that there was a sudden peak with the capacity of change, when I measured the capacity of change, cubical expansion and Thermally Stimulated Current on the Cross - Linked Polythylene. Crystal melting began at 375 K and changed into formaless shapeless at 380 K. The conduct of a particle on the surfase of dipole, electron trap was founded to be ion conduction nature under the low electronic field, wherase, the electron nature under the high electronic field. Consequentity, under the semi-conduction layer electronic a particle was injected to inter-fase and accumulated for a time and appeared to be TSC.

• Transactions on Electrical and Electronic Materials
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• v.1 no.1
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• pp.45-52
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• 2000

The conduction characteristics in Oriented polypropylene (OPP) film were studied over electric field intensities between 10 M/V m and 300 M/V m . The range of the conduction characteristics was divided in to five regions with increasing field intensity. Particularly, in the region from 70 Mb/m to 82 MV/m voltage-controlled negative resistance was displayed. In the negative resistance region current oscillations were also observed the negative resistance characteristics could by explaine by Gibbons theory.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.12
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• pp.601-608
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• 2005

This paper presents a novel single-stage high-power-factor electronic ballast for fluorescent lamps operating in critical conduction mode. The proposed topology is based on integration of boost converter as power factor corrector(PFC) and a half-bridge high frequency parallel resonant inverter into a single stage. The input stage of the boost converter is operating in critical conduction mode for positive and negative half cycle voltage respectively at line frequency(60Hz). So that a boost converter makes the line current follow naturally the sinusoidal line voltage waveform. The simulated and experimental results for 100W fluorescent lamps operating at 42kHz switching frequency and 220V line voltage have been obtained. This proposed inverter will be able to be practically used as a power supply in various fields as induction heating applications, fluorescent lamp and DC-DC converter etc.