• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1052-1058
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• 2003

The possibility of micro/nano machining through electro-chemical process is discussed in this research. Electro-chemical dissolution region is localized within 1 ${\mu}m$ by applying ultra short pulses with tens of nanosecond duration. The effects of voltage, pulse duration, and pulse frequency on the localization distance are investigated. Localization distance can be manipulated by controlling the voltage and pulse duration, and various hole shapes are produced including stepped holes and taper free hole. High quality micro-hole with 8 ${\mu}m$ diameter with 20 ${\mu}m$ depth and micro-groove with 9 ${\mu}m$ width with 10 ${\mu}m$ depth are machined on 304 stainless steel.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.356-361
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• 2003

Electrochemical micromachining which is not normally considered as a precision process is presented in this paper. The application of voltage Pulses between a tool electrode and a workpiece in an electrochemical environment allows the three-dimensional machining of conducting materials with micrometer precision. In this paper tool-electrodes($5\mu\textrm{m}$ in diameter, 1mm in length) are developed by electrochemical micromaching and micro holes are manufactured using this tool-electrodes we developed already. Micro holes are achieved the accuracy below $50\mu\textrm{m}$ in diameter using ultrashort voltage pulses(0.1-5$\mu\textrm{s}$).

• Journal of the Korean Society for Precision Engineering
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• v.20 no.9
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• pp.32-39
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• 2003

Pulse electrochemical machining process with high or low current density may produce a non-lustrous surface on workpiece surface. The usual polishing process to remove a black layer from the surface has been hand polish the part. But the milli-to-micro meter scale structure formed by the electrochemical machining process may be destroyed while polishing process. The application of ultra short voltage pulses based on the analysis of electrical double layer charging process allows high resolution electrochemical machining and polishing. This technique was based on the specific polarization resistance from the comparison of ideal and experimental potential variation during short voltage pulses.

• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.360-365
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• 2020

A technique for the reduction of pulse pile-up effect in digital pulse-shape discrimination (PSD) of neutrons and gamma-rays with organic scintillation detectors is presented. The technique is based on an electronic reduction of the effective decay-time constant of scintillation pulses while retaining the PSD information of the pulses. The experimental results obtained with a NE213 liquid scintillation detector in a mixed radiation field of neutrons and gamma-rays are presented, demonstrating a figure of merit (FOM) of 1.20 ± 0.05 with an energy threshold of 350 keVee (electron equivalent energy) when the effective length of the pulses is reduced to 50 ns.

• Korean Journal of Optics and Photonics
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• v.12 no.1
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• pp.1-4
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• 2001

Via terahertz (THz) reflection radar, the characterizations of reflected THz electromagnetic pulses are reported. Quasi-optical techniques are used to efficiently reflect pulses of THz electromagnetic radiation from an aluminum mirror and several conducting and nonconducting materials. An incident THz pulse is reflected up to 9 times to know the magnitude change of a reflected pulse from the aluminum mirror. Using this method, aluminum board, undoped silicon, quartz, and LDPE samples' reflection coefficient and index of refraction can be measured. These results suggest a possible application of transient THz reflection spectroscopy without surface contact.ontact.

• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.181-184
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• 2002

In this paper, an algorithm is proposed for the automatic movement of the platform on a ladder lift which operates by using hydraulic force. Experimental data of the manual movement operated by experts are acquired and analyzed. The length of movement of the platform is estimated by the number of pulses from an encoder while the platform is moving. The operating characteristics have been extracted from the data. The number of pulses varies whenever the weight of load varies. We propose a model to compensate the difference of the number of pulses. An automatic movement algorithm based on the model is proposed. The platform can start and stop smoothly at the starting point and the destination point. Experimental results show that the error distance at the destination point is less than 5 cm when the length of the ladder is 23 m.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.6 no.4
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• pp.53-59
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• 1992

This paper describes an instrument for the detection and geometric location of partial discharge (PD) source in transformers. This instrument measures electric current pulses and ultrasonic pulses simultaneously, counts the number of electrical pulses and determines the geometric location of PD in transformers. It was found that there is a relationship between partial discharge magnitude and pulse repetition rate when the applied test voltage and oil temperature were varied. Through the laboratory test using model transformer, it was clarified that this detector could be used for detecting and locating PD in the transformer.

• The Journal of the Korea Contents Association
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• v.6 no.2
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• pp.59-64
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• 2006

In this paper, 1 propose a new method of Multi-Pulse Coding(IP-MPC) use individual pitch pulses in order to accommodate the changes in each pitch interval and reduce pitch errors. The extraction rate of individual pitch pulses was $85\%$ for female voice and $96\%$ for male voice respectively, 1 evaluate the MPC by using pitch information of autocorrelation method and the IP-MPC by using individual pitch pulses. As a result, 1 knew that synthesis speech of the IP-MPC was better in speech quality than synthesis speech of the MPC.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.465-468
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• 2001

An objection of this study is to develop a high stable analytic system of radioactive pulses. The proposed system consists of an amplifying circuit with 60dB gain, a programmable power supply unit which can generate DC voltage up to 1, 500V, and a digital signal processor. Pulse height distribution in accordance with pulse counts is important data in analyzing radioactive pulses. In this study, AD convertor (12bit, l00ns) and DSP (TMS 320C31-60) are used to analyze the pulse height, and the analytic system is designed to be operated in PC-networking.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.83-86
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• 2002

This paper presents a new self-erasing discharge mode for the improvement of luminous efficiency and color purity of an AC plasma display panel (AC PDP). A new self-erasing discharge mode is produced between successive sustain pulses. by simultaneously applying the auxiliary short pulses at the falling edge of the sustain pulses without cross-talk during a sustain period. As a result. the luminous efficiency and color gamut are improved by 16% and 5%, respectively.