• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.6
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• pp.1-9
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• 2003

In this paper, we propose a new fingerprint feature extraction method using the convex structure. A fingerprint minutiae flows along the uniform direction and is regarded as a sinusoidal signal across the normal direction. Local maxima of the signal represent coarse thinned one-pixel-wide ridges in which the convex region of the signal correspond to ridges. The proposed fingerprint feature extraction method detects the convex structure and local maxima. Finally fingerprint features are extracted from one-pixel-wide ridges. Because it has no parameter, it is efficient for various fingerprint identification systems.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.389-392
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• 2016

As technologies evolve, 3D measurement techniques using cameras have been developed continuously. In 3D measurement, high accuracy, fast speed, and easy implementation are very important factors. Recently, 3D measurement using multi-frequency fringes has been widely used. This method is generally a method of measuring the height of a image obtained by projecting a sine wave through the projector. The sine wave is produced by software. However, this sine wave is not a perfect sine wave by gamma of projector. This is given a bad influence on the height measurement, and can not measure the correct height. In this paper, we propose a method for correcting the phase of the sine wave to avoid being affected gamma. Through this method it will be able to make more accurate height measurement.

• Journal of the Korean Magnetics Society
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• v.7 no.5
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• pp.232-236
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• 1997

We have gone into details about the velocity calibration of sinusoidal mode for Mossbauer spectrometer. Since sinusoidal Mossbauer spectrometer has a ${\gamma}$-ray source that oscillates at the end of loudspeaker with the natural frequency. Doppler velocity is accurate and stable. From the analyzing Mossbauer spectra of $Fe_3O_4$ and U $Fe_3O_4$ (unbalanced $Fe_3O_4$), we have shown the power of correct velocity for sinusoidal mode.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.269-270
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• 2012

이 논문에서는 Fly-Back-Converter로 Interleaving 동작하는 계통연계형 마이크로 인버터를 연구하고 200W급 태양전지 모듈에서 발생되는 전기에너지를 효율적으로 이용하여 계통에 연계하기 위한 전력변환시스템 개발을 목표로 하고 있다. 저렴하면서 효율이 높은 계통연계 인버터를 실현하기 위해서는 기존의 중앙집중식 인버터 구조와 다른 접근이 필요하다. 따라서 영전위 소프트 스위칭이 가능한 2병렬 인터리빙 구동의 Fly-Back DC/DC 컨버터 토폴로지로 입력 단 회로를 구성하여 모든 전력변환 동작이 일어나도록 한다. 출력전류를 사인파 open loop로 제어를 하고 CRM(Critical Conduction Mode) 스위칭 동작으로 높은 효율로 작동을 실현시켰다. 이 논문에서는 인터리빙으로 동작하였을 시 200W급 출력으로 나올 수 있는 전류 최대치를 계산 하였고 출력 전류가 사인파로 동작하게 제어방법을 기재하였다.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.3
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• pp.192-198
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• 2007

In this paper, a new method to reduce the size of ROM in the direct digital frequency synthesizer(DDFS) is proposed. The new ROM compression method can reduce the ROM size by using the two ROM. The quantized value of sine is stored by the quantized-ROM(Q-ROM) and the differential ROM(D-ROM). To reduce the ROM size, we use the differential quantization technique with this two ROM. First, we quantize the quarter sine wave with the $2^L$ address and store the quantized value at the Q-ROM. Second, after the $2^L$ address are equally divided into $2^M$ sampling intervals, the sampling value is quantized. And the D-ROM store only the difference between this quantized value and the Q-ROM. So the total size of the ROM in the proposed DDFS is significantly reduced compared to the original ROM. The ROM compression ratio of 67.5% is achieved by this method. Also, the power consumption is affected mostly by this ROM reduction.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.3
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• pp.239-246
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• 2006

This paper suggests a new modulation strategy for step pulse type multi-level inverter. The proposed strategy is simple to determine the switching angles without regard to increase of levels. Designed to extract the equivalent RMS value compared to ideal sine wave from inverter, it can be applied effectively to high level step pulse inverter. Also this paper proposed modulation strategy for modified H-bridge 13 level inverter which has different cell source voltages with simulation and experiment. The modulation characteristics from simulation and experiment, agreed very well with tracing sine wave about modified structure of cascaded H-bridge multi-level inverter.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.1
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• pp.61-68
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• 2018

This paper is elaborates on the pure sine wave single phase inverter of 500W level which is driven by battery. The inverter is structured to raise the battery voltage to 400V by using the push-pull topology, and by using H-bridge with the high voltage, it outputs common 220VAC. This topology is utilized to use the power semiconductor device in order to design and manufacture the inverter of 500W at input voltage rating of 12VDC. As a result, the efficiency exceeds 90% in partial sections, but on average, the efficiency is approximately 89.5%, and as for output voltage, frequency fluctuation range and THD, the result can be less than ${\pm}5%$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.401-404
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• 2009

In this paper, a new method to reduce the size of ROM in the direct digital frequency synthesizer(DDFS) is proposed. The new parallel ROM compression method can reduce the ROM size by using the two ROM. The quantized value of sine is stored by the quantized-ROM and the differential ROM. To reduce the ROM size, we use the differential quantization technique with this two ROM. So the total size of the ROM in the proposed DDFS is significantly reduced compared to the original ROM. The ROM compression ratio of 67.5% is achieved by this method. Also, the power consumption is affected mostly by this ROM reduction.

• The Journal of the Acoustical Society of Korea
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• v.42 no.4
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• pp.320-328
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• 2023

Underwater active target detection is vital for defense systems, requiring accurate detection and estimation of distance and velocity. Sequential transmission is necessary at each beam angle, but divided pulse length leads to range ambiguity. Multi-frequency transmission results in time-bandwidth product losses when bandwidth is divided. To overcome these problem, we propose a novel method using Generalized Sinusoidal Frequency Modulation (GSFM) for rapid target detection, enabling low-correlation pulses between subpulses without bandwidth division. The proposed method allows for rapid updates of the distance and velocity of target by employing GSFM with minimized pulse length. To evaluate our method, we simulated an underwater environment with reverberation. In the simulation, a linear frequency modulation of 0.05 s caused an average distance estimation error of 50 % and a velocity estimation error of 103 % due to limited frequency band. In contrast, GSFM accurately and quickly tracked targets with distance and velocity estimation errors of 10 % and 14 %, respectively, even with pulses of the same length. Furthermore, GSFM provided approximate azimuth information by transmitting highly orthogonal subpulses for each azimuth.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1029-1031
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• 2001

In this paper, we propose a three-phase soft-switching PWM-PFC converter and describe the circuit operations and the experimental results. The proposed converter is constructed by using a resonant network in parallel with the main switch of the conventional PWM converter. A new PWM-PFC converter achieves including the auxiliary switches without increasing their voltage and current stress.