• Journal of the Korean Geotechnical Society
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• v.30 no.4
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• pp.81-92
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• 2014

The integrity evaluation of river levee includes slope stability evaluation of riverside land and protected low-land, and safety of piping with respect to critical gradient and critical velocity based on related regulations, such as Design Criteria Rivers Commentary (2009), Structural Design Criteria Based Commentary (2009). The design hydro-graph is the most important design input factor for the integrity evaluation; it can be inaccurate due to the absence of its decision methods suggested by the national level. The authors in this paper evaluated numerical analytic levee integrity for piping and slope stability by changing each design hydro-graph, including rising ordinary water level, lasting flood water level, falling water level, and flood frequency for Mun-san-jae on Nak-dong River. Finally, the authors suggested that the levee integrity of piping and slope stability are very sensitive to the changes of increasing time of ordinary water level by 57 hours and lasting time of the flood water level by 53 hours, respectively, for Mun-san-jae.

• Journal of the Korean Magnetics Society
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• v.22 no.5
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• pp.178-182
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• 2012

This research suggested that the extraction of respiratory rate could be made possible by using frequency analysis in the data process for clip-type pulsimeter equipped with permanent magnet and Hall sensor. The pulse analysis included of cardiac motion information depending on variation of pulse waveforms is investigated by means of Fast Fourier Transformation (FFT). The peaks of FFT spectrums measured at 15, 20, 30, 40, and 50 tempos are coincided to each respiratory rate having 0.125 Hz, 0.16 Hz, 0.25 Hz, 0.33 Hz, and 0.41 Hz, respectively. The FFT spectrum using algorithm for the extraction of respiratory rate showed the best pulse waves measured during 300 s. Based upon these results, the clip-type pulsimeter could extract the effective respiratory rate reflecting physical effects.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4740-4744
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• 2012

The purpose of this paper was to make a LED light control module using Zigbee. The module was made so that brightness of the LED light changes according to the ambient brightness. A 8-bit microcontroller was used to implement the module to enable LED dimming and wireless light intensity measurement. Using the proposed method, power consumption can be improved by up to 48% on average, with 3.4-0.4W changes in power. The measured ambient light intensity values are converted from analog to digital and outputted as a PWM waveform. According to the output waveform and changes in the current outputted from the LED driver, the brightness of the LED light is controlled. Also, Zigbee with close-range wireless communication capabilities was used to enable wireless transmission of light intensity measurements.

• Tribology and Lubricants
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• v.7 no.1
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• pp.61-67
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• 1991

기계평면시일의 접촉 운동면에서 유체가 비압축성이고, 점성의 영향을 받는 경우에 대한 체적누설 유동량과 마찰 토오크를 멱급수의 방법을 이용하여 추정하였다. 본 연구에서 고려되고 있는 설계인자로 시일의 경사도, 접촉 운동면에서의 사인파형, 코우닝, 열탄성 변화량, 마모량, 시일의 스프링 강성도에 따른 축방햐의 변화량을 종합적으로 고려하여 해석하였다. 계산된 결과에 의하면 특히 회전속도가 증가되면 열탄성 변화량에 의한 시일의 누설 마찰 토오크가 커다란 영향을 받고 있는 것으로 나타나고 있다.

• Tribology and Lubricants
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• v.6 no.2
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• pp.34-42
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• 1990

기계명면시일의 접촉 운동면에서 유체가 비압축성이고, 점서의 영향을 받는 경우에 대한 체적 누설 유동량과 마찰 토오크를 멱급수의 방법을 이용하여 추정하였다. 본 연구에서 고려되고 있는 설계인자로 시일의 경사도, 접촉 운동면에서의 사인파형, 코우닝, 열탄성 변화량, 마모량, 시일의 스프링 강성도에 따른 축방향의 변화량을 종합적으로 고려하여 해석하였다. 계산된 결과에 의하면 특히 회전속도가 증가되면 열탄성 변화량에 의한 시일의 누설 유동량과 마찰 토오크는 커다란 영향을 받고 있는 것으로 나타나고 있다.

• The Journal of the Acoustical Society of Korea
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• v.18 no.7
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• pp.75-79
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• 1999

The beam patterns of source array and changes in the far-field signatures are compared and analyzed each other in order to identify the seismic capability affected by the misfired source at the multi-channel seismic source array. In the primary pulse amplitude of far-field signature, the 66% of seismic capacity are sustained if approximately 40% of source are misfired among whole gun volume. When the sources with the same distances are misfired at the 154㎐, the beam width of the long- and wide-array which is identical regardless of arraying pattern. The beam width has a tendency to narrow now from 41 to 34 according to increase the volume of misfired source at the long-array beam pattern. Therefore, the source array of small volume are suitable for the shallow seismic survey because of producing adequate beam patterns with narrow beam width.

• The Journal of the Acoustical Society of Korea
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• v.8 no.5
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• pp.33-50
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• 1989

In this paper, musical tone, especially instrument tones are synthesized using nonlinear distortion technique. Nonlinear distortion is very simple but versatile method when you synthesize musical instrument tones. It basically consists of one sine oscillator and amplifier which makes distortion to Input wave. Output wave has many harmonics that can be controlled by varying shaping function, which is the transfer function of nonlinear amplifier. Shaping function Is obtained from the analyzed harmonic amplitude data. Given harmonics amplitudes, Chebyshev polynomial is used to produce the shaping function that exactly makes the given harmonics at steady state. We contructed non -real time nonlinear distortion synthesizer program running at IBM-PC. To quantify the satis faction of synthesised tones, listening test is carried out, and the result is presented.

• Tunnel and Underground Space
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• v.16 no.4 s.63
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• pp.326-333
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• 2006

In this study, the vibration waveform of the single hole which is not interfered from the different blasting holes is separated, the each dominant frequency which is determinated through the Fast Fourier Transform(FFT) is measured. Also the separation waveform executed a superposition modeling which changes to delay time from 1ms to 80 ms in 1ms interval and controls the number of blasting holes from 2 holes to 15 holes in order to investigate the effect of PPV according to the duration time of the vibration and the number of blasting holes. As a result of analysis, the longer the duration time of the vibration, the longer the delay time which is not interfered from the different blasting holes and the effect regarding the number of blasting holes from inside identical delay time did not appear a lot.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.720_721
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• 2009

일반적으로 BLDC 모터는 고효율 고토크의 특성을 가지고, 넓은 속도 범위에 걸쳐 높은 효율을 유지 하고 제어가 용이하므로 널리 사용 되고 있다. 이러한 BLDC 모터는 구동 원리에 의해서 역기전력의 파형이 구형파를 가지는 것이 유리하다. 또한 BLAC 모터는 효율, 역률, 전력밀도 및 토크 밀도가 높은 장점을 가지고 정현파 역기전력을 요구한다. 매입형 영구자석형 동기전동기 중 할박 구조로 인해서 자속을 집중 시키는 Spoke type 모터의 회전자 표면은 철심으로 이루어져 있기 때문에 회전자 표면의 형상을 Arc설계를 통해서 형상 최적화가 가능하다. 회전자 표면의 Arc 설계를 통해서 공극의 자속밀도 분포의 변화를 줄 수 있어 BLDC 구동 시 요구하는 구형파 역기저력 파형과 BLAC 구동 시 요구되는 정현파 역기저력 파형을 Arc 설계 각도에 따라 다르게 발생 시킬 수 있다. 이를 통해서 역기전력을 형태를 구형파와 정현파 형태를 가지도록 설계하여 BLDC와 BLAC 구동 시에 성능을 FEA를 통해서 비교 평가 하여, 구동 방식에 따른 Spoke type IPM 모터의 형상 설계방법을 제시한다.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.10 no.5
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• pp.66-74
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• 1996

In this paper, the arc currents, voltages and these waveforms were investigated when negative DC high voltages applied to neddle-pane electrodes to study arc quenching phenomena of DC interruption in the. magnetic field. The conclusion of this study are as follows : There are no dynamic arc characteristics in the no magnetic field. Not only dynamic arc characteric but also zero points of arc current which are generated from repeating frequence of arc discharge under the magnetic fields were observed. The more magnetic field were applied, the repeating frequence of arc discharge were more increased..