• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.2
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• pp.110-117
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• 1998

An optical modulator with CPW(coplanar waveguide) electode on Ti:LiNbO$_{3}$ optical waveguide wasfabricated and characterized. The electrical-optical bandwidth measurement showed an optical response of -3dBat 10 GHzand S$_{11}$ lessthan -10dB upto 20GHz. The typeical specifications are : 5.6V of driving voltage, 4.2dB of insertion loss and 30dB of on/off extinction. The eye pattern proved that the optical meduator, fabricated in this work, has properties good enough for application.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2069-2072
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• 1999

The extended 765 kV system may have severe electrical transients according to the interconnection of transmission lines and have long transmission line over 250 km. So we need to analyze the transient phenomena to confirm the insulation coordination which is designed for 765 kV project step I. In particular, this paper shows the analysis results of secondary arc extinction by HSGS (high speed ground switch) application. The EMTP/MODELS were used to simulation study of secondary arc phenomena. We had confirmed the TRV(transient recovery voltage) and rated current of HSGS which will be used in the KEPCO 765 kV system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.817-820
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• 2002

In this letter, we developed a 400Gb/s optical transmitter using an electroabsorption modulator and measured its characteristics. As a result, the extinction ratio, the output power and the wavelength are varied while DC bias voltage and temperature of an electroabsorption modulator are changed. Based upon these experimental results, a design of 400Gb/s optical transmitter can be optimized.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.95-96
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• 1998

An optical modulator with CPW electrode on Ti:LiNbO$_3$ optical waveguide was fabricated and chterized. The electrical-optical bandwidth measurement showed an optical response of -3dB at 10 GHz and S11 less than -l0dB unto 20GHz. The typical specifications are . 5.6V of driving voltage, 4.2dB of Insertion loss and 30dB of on/off extinction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05c
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• pp.31-35
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• 2004

We propose driving method of Ultraviolet sensor for fire alarms using pulse width modulation that used to fire detector with sensor of private-use detectable light energy as ultraviolet in energy of electromagnetic-wave type radiate from flame, when combustible burn with contain carbon,. Ultraviolet sensor is UV Tron using gas multiplication effect to current discharge and photoelectric effect of metal. To have high sensibility and to gain proper output voltage, it has high responsive performance. This research designed driving circuit with UV sensors and proposed method of false alarm reduced to resemble fire. the result propers the prevention and extinction of fire technique degree, certificated operation of detector.

• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.532-539
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• 1996

Diamond-like carbon (DLC) films were deposited on silicon substrates by the plasma decomposition of hydrocarbons under various conditions, and studied by the spectroscopic ellipsometry (SE). We used the effective medium approximation with the dispersion model developed by Forouhi and Bloomer to determine simultaneously both the structure and the optical constants of the DLC films from their ellipsometric spectra. Especially, we investigated the variation of the multilayer structure including the interface layer, of the refractive indices, and of the extinction coefficients as the deposition conditions were varied; substrate pretreatment procedure, hydrocarbon precursors, and the substrate bias voltage were varied.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1517-1518
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• 2006

This paper describes the design and fabrication of a partial discharge(PD) analyzer to evaluate insulation performance for low-voltage electrical and electronic devices. The analyzer consists of an adjustable AC power supply, a coupling network, an amplifier, a shielding encloser, a sample-hold (S/H) circuit and a data acquisition (DAQ) board. The analyzer holds the height of PD pulse for $10{\mu}s$ by the S/H circuit, and this makes possible to measure PD pulses having fast rise and short duration by a low speed analog-to-digital (A/D) converter. The data are transmitted to the personal computer through the DAQ board, and the designed analysis program calculate apparent charges, discharge inception and extinction voltages.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.11
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• pp.2229-2235
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• 2009

In this paper, each specimen blended at weight proportions of 80% HDPE to 20% EVA, 70% HDPE to 30% EVA, 60% HDPE to 40% EVA, and 50% HDPE to 50% EVA was manufactured respectively. The insulation performances of the proposed insulator were compared with conventional XLPE, main insulating material of CV cable on the basis of the investigation results of DC insulation performances. From the space charge density, electric field and potential profiles with raising DC voltage and time variation in HE82, distortion of electric field distribution was improved. As EVA mixed into the bulks acts as nucleation in crystallization process of HDPE, the size of spherulites became decreased and finally formed continuous network structure. Ultimately, it resulted from extinction of space charge in the interfacial region of spherulites.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.2
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• pp.184-190
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• 2009

One of the purposes of arc control is to change its state to the diffuse state before current zero as soon as possible. This can provide optimal conditions for full extinction of arc by minimizing the quantity of residual plasma between contacts near current zero. TRV(transient recovery voltage) occurs at current zero at the same time with current interruption. If there is substantial residual plasma near current zero it can cause 'post arc current' by the interaction of its conductance with TRV. In this paper, arc control ability as a function of configuration of spiral type VI contacts was compared on the criteria of the time taken for arc to reach to the diffuse state.

• Current Optics and Photonics
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• v.6 no.1
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• pp.15-22
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• 2022

This paper describes the construction of a phase shifter with low loss and small volume. To construct it, we use the two graphene layers that are separated by a hexagonal boron nitride (hBN) and embedded in a silicon waveguide. The refractive index of the waveguide is adjusted by applying a bias voltage to the graphene sheet to create an optical phase shift. This waveguide is a compact device that only has a radius of 5 ㎛. It has a phase shift of 6π. In addition, the extinction ratio (ER) is 11.6 dB and the insertion loss (IL) is 0.031 dB. Due to its unique characteristics, this device has great potential in silicon on-chip optical interconnection and all-optical multiple-input multiple-output processing.