• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.2
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• pp.28-34
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• 1994

In this paper, a new time-domain parameter extraction method for speech recognition is proposed. The suggested emthod is based on the fact that the local peak-to-peak interval, i.e., the interval between maxima and minima of speech waveform is closely related to the frequency component of the speech signal. The parameterization is achieved by a sort of filter bank technique in the time domain. To test the proposed parameter extraction emthod, an isolated word recognizer based on Vector Quantization and Hidden Markov Model was constructed. As a test material, 22 words spoken by ten males were used and the recognition rate of 92.9% was obtained. This result leads to the conclusion that the new parameter extraction method can be used for speech recognition system. Since the proposed method is processed in the time domain, the real-time parameter extraction can be implemented in the class of personal computer equipped onlu with an A/D converter without any DSP board.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.264-269
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• 1998

A proposed soft-switching buck-boost PWM converter has a lot of advantages, Viz., electric isolation, a high power factor, low switching losses, low EMI noise, reduction of the voltage and current stresses, etc. In a new PFC converter, the switching device is replaced by the loss-less snubber circuit to achieve the zero voltage switching (ZVS) at the maximum current. However, the charging current of the capacitor in the loss-less snubber circuit distorts the input current waveforms. To improve the input current waveform, a new duty factor control method is proposed in this paper.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.551-554
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• 2002

This paper describes a new interactive inverter between a photovoltaic(PV) array and single-phase utility that avoid the bulky input (60Hz) transformer on the AC side. The interface employs a pwm boost converter on the DC side followed by a pwm current-forced single-phase rectifier for injecting the power from the PV array into the mains. The current waveform at the AC side remains sinusoidal and exactly in phase at all time. The circuit also has the advantage of requiring fewer switching device than high-frequency link system. This paper describes modeling of PV array and new system topology. Simulation results on the performance of the connection are also presented.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.1002-1007
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• 2003

A new driving circuit for the SPSS (Single-Pulse Soft-Switching) PFC converter is proposed. The switching device of a SPSS converter switches once In every half cycle of an AC commercial power source. Therefore, it can be solved many problems caused by the high frequency operation. The proposed SPSS converter achieves the soft-switching operation and the EMI noise can be reduced. The resonant capacitor voltage supplies to the resonant inductor even if the input AC voltage is the vicinity of zero cross voltage. Then, the power factor and input current waveform can be improved without delay time. A new driving circuit achieves the operation of SPSS converter by one switching drive circuit. The proposed converter can be satisfied the IEC standard sufficiently.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.203-206
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• 2002

In this study, a new driving method is suggested to improve the dark room contrast ratio. The principles of the method are that the reset facing discharges occur between scan and address electrodes instead of surface discharge and that the discharge occurs only for the cells that experienced sustain discharge in preceding sub-field after the first sub-field. The dark room contrast ratio is improved more than 7 times compared with the conventional method.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.33 no.11
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• pp.425-432
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• 1984

This paper is to propse a new self-excitation method of synchronous generator. Instead of conventional exciter of synchronous generator, the additional winding which is arranged in addition to the armature winding, is used in this generator. The output terminal of the additional winding is connected to a capacitor and to a full wave rectifier in series. In this configuration, one source double excitation which is composed of capacitor-self-excitation by lead urrent and direct current excitation by rectifier, is induced. The result is that` The excetation efficency is improved greatly and output waveform is improved also. In three-phase synchronous generator using the new method of the one source double excitation, voltage element (shunt characteristics) and current element (series characteristics)are compounded in scalar by adapting star-point-open-rectifier system. The result is as following` The effect of load power factor angle on voltage regulation is reduced greatly, compound characteristics is become manifold by controlling capacity of capacitor, and transient response is improved.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.71-74
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• 2005

There have been various efforts to achieve a better PDP TV, which have low power consumption, high image quality and low price. As the results, the power consumption of LG's new 42 inch HD PDP could be lower than 42 inch LCD under the general movie display load condition. And the address discharge time lag of ${\sim}1\;{\mu}s$ for 42 and 50 inch XGA single scan by which the cost can be reduced and image quality can be improved was achieved by using new MgO material and driving waveform. In addition, we have suggested TCA (Triangular Color pixel Arrangement) cell structure for realizing the full HDTV of 60inch diagonal size, which has $1920{\times}1080$ resolution. The luminous efficiency of the suggested TCA structure has been increased about 40% compared with that of the conventional cell structure.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.124-129
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• 2007

For seismic imaging and inversion, the inverted image depends on how we define the objective function. ${\ell}^1$-norm is more robust than ${\ell}^2$-norm. However, it is difficult to apply the Newton-type algorithm directly because the partial derivative for ${\ell^1$-norm has a singularity. In our paper, to overcome the difficulties of singularities, Huber function given by hybrid ${\ell}^1/{\ell}^2$-norm is used. We tested the robustness of our new object function with several noisy data set. Numerical results show that the new objective function is more robust to band limited spiky noise than the conventional object function.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.297-300
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• 2008

This paper described a New-Concept lightning warning system (LWS) which can measure electric field intensity on the ground level by an electric field mill (EFM) and calculate the lighting location by radiated electro-magnetic waveform. The EFM measures electric field up to 20[kV/m] with the sensitivity of 0.15[V/kV/m] and frequency bandwidth of the loop antenna was ranges from 5.2[kHz] to 1.71[MHz]. The LWS provides data on the movements of thunderclouds and the possibility of lightning return stroke.

• Journal of the Korean Institute of Telematics and Electronics
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• v.12 no.4
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• pp.46-49
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• 1975

Mallory의 회로를 변형하여 변압기를 사용하지 않은 새로운 배전압회로를 구성하였고 직류출력전압의 regulation에 있어서 Mallory의 회로보다 훨씬 우수한 결과를 얻었다. 또 출력파형을 해석하고, 직류출력전압과 출력전류와의 관계를 간결한 반사식으로서 표현하였고 이 관계식이 실험결과와 잘 부합되어 있음을 보였다. In this paper, a new transless voltage doubler circuit which is a modification of Mallory circuit is proposed, Regulation characteristics of the new circuit is much superior to that of Mallory's. The analysis of output waveform is applied, an4 a simple and practical relation between dc output voltage and dc output current is derived. It is shown that this formula is coincide with the experimental results.