• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1630-1633
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• 2002

In this paper, we proposed a new control system of the dividing ratio changeable type ADPLL (DCPLL). The DCPLL has been designed by us. However, in the DCPLL, there are some problems such as this curcuit is increased the output jitter on multiple frequency, and the output jitter is large on steady state. Then, the output jitter characteristic on multiple frequency is improved by using “rest-control” system. Also, output jitter decreases by using “W-edge (positive edge h negative edge)” system. We confirmed some characteristics of the DCPLL with the circuit simulator, PSpice.

• 한국전기전자재료학회논문지
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• 제24권11호
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• pp.865-869
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• 2011

A cantilever-type piezoelectric generator has advantages of simple structure, ease of fabrication and large displacement by transverse vibration of a beam. It is easy to control the natural frequency, and also possible to increase the output power by changing the length, width, and thickness of the generator. In particular, the length increases, the natural frequency sharply decreases, and vice versa. Hence, the natural frequency can widely be controlled by using change in the length of elastic body. In this paper, the generator was designed and fabricated to change natural frequency using the slides of the case. In addition, the generating characteristics were confirmed through finite element analyses and vibration experiment. As a result, the maximum output characteristics could be generated due to resonance phenomenon although any frequency of external force was applied.

• 대한전자공학회논문지
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• 제10권3호
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• pp.61-68
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• 1973

한글 자음을 sona-grap로 부터 얻은 음성 pattern으로 주파수분석적인 방법으로 정밀분석한다는 것은 지극히 곤란한 것이며 주파수합성적인 방법으로 연구해야 할 문제임을 알았다. 그래서 자음 주파수영역을 분석추출하였으며, 전자음에 후독하는 $\mid$ㅏ$\mid$의 format가 조음방법과 조음위치와 대응해서 변화하는 상태를 주로 관찰하였다.

• 사상체질의학회지
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• 제10권1호
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• pp.215-233
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• 1998

본 연구(硏究)는 1998.1월(月)에서 1998.6월(月)사이에 동의대학교(東義大學校) 한의과대학(韓醫科大學) 부속한방병원(附屬韓方病院)에 입원(入院) 가료중(加h療中)인 환자 27명을 대상(對象)으로 하였으며, 사상체질(四象體質)의 판별(判別)은 사상체질분류검사(四象體質分類檢査)(QSCCII)를 중심으로 하였다. 본 결과는 사상체질분류검사(四象體質分類檢査)(QSCCII)와 사상학회(四象學會) 부산시지부(釜山市支部)에서 사용하고 있는 설문지(說問紙)를 비교하여 얻은 것이다. 1. 얼굴모양에 있어서는 태음인(太陰人)과 소양인(少陽人)에 비하여 소음인(少陰人)이 "눈코입이 작고 섬세한 편"이라고 대답하는 빈도가 높았다. 2. 걸음걸이에 있어서는 태음인(太陰人)과 소음인(少陰人)이 소양인(少陽人)에 비하여 "걸음이 빠르고 몸을 흔든다."라고 대답하는 빈도가 낮았다. 3. 피부(皮膚)에 있어서는 소양인(少陽人)에 비하여 소음인(少陰人)이 "희고 마른 편이다"라고 대답하는 빈도가 높았으며, 태음인(太陰人)은 빈도가 낮았다. 4. 피부(皮膚)에 있어서는 "피부가 부드럽고 마른 편이다."라는 항목에서는 소양인(少陽人)과 태음인(太陰人)이 소음인(少陰人)에 비하여 낮은 빈도를 보이고 있었다. 5. 전반적인 얼굴에서 느껴지는 느낌에서는 "단정하다."라는 항목에서 태음인(太陰人)에 비하여 소음인(少陰人)은 높은 빈도의 대답을 하였으며, 소양인(少陽人)은 낮은 빈도의 대답을 하였다. 6. 한출(汗出)에 있어서는 태음인(太陰人)이 소양인(少陽人)과 소음인(少陰人)에 비하여 "대체로 땀이 적은 편이거나 땀이 다른 사람보다 적다"라고 대답하는 빈도가 낮았다. 7. 식욕(食慾)에 있어서는 소양인(少陽人)과 태음인(太陰人)에 비하여 소음인(少陰人)이 "기분에 따라 식욕이 증가되거나 감소되는 편차가 심하다"라고 대답하는 빈도가 높았다. 8. 대변(大便)에 있어서는 "평소에 대변이 무른 것보다 단단해야 건강 상태가 좋다."라는 항목과 "대변이 무르거나 설사가 나면 건강 상태가 나빠진다.(찬 것, 기름진 것을 먹으면 심하다.)"라는 항목에서 소양인(少陽人)에 비하여 소음인(少陰人)은 그렇다고 대답하는 빈도가 높았으며 태음인(太陰人)은 그 빈도가 낮았다. 9. 소변(小便)에 있어서는 소음인(少陰人)에 비하여 소양인(少陽人)과 태음인(太陰人)이 "몸에 열이 많으면 갈증이 나서 물을 먹는데 먹는 것보다 소변량이 더 많이 보게 된다."라고 대답하는 빈도가 낮았다. 10. 피부(皮膚)에 있어서는 소양인(少陽人)과 태음인(太陰人)에 비하여 소음인(少陰人)은 "피부가 매끈매끈하다."라고 대답하는 빈도가 높았다. 11. 평소에 느끼는 자각증세에 있어 소음인(少陰人)에 비하여 소양인(少陽人)과 태음인(太陰人)에게서 "건망증(健忘症)"이라고 대답하는 빈도가 낮았다.

• 한국자동차공학회논문집
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• 제9권4호
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• pp.193-203
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• 2001

The Monte Carlo method was used to evaluate the reliability of crash discrimination algorithms. Through the Fast Fourier Transformation, crash pulses obtained during frontal crash tests of a mini van and a sports utility vehicle were transformed to signals in the frequency domain, and the signals were divided into basic signals and changeable signals. The changeable signals were modified through random generation, and they were combined with the basic signals. Then, the combined signals were transferred back to the time domain. In this way numerous crash pulses could be generated. For the generated pulses, crash discrimination algorithms were evaluated by examining whether they did not result in air bag deployment for the pulses requiring no air bag deployment and whether they resulted in time-to-fires faster than required time-to-fires for the pulses requiring air bag deployment. The crash discrimination algorithm in which the absolute value of the deceleration change multiplied by the velocity change or the summation of the absolute value of the deceleration change was used as a metric was Proven to be highly reliable.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제29회 KOSCI SYMPOSIUM 논문집
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• pp.152-160
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• 2004

Studies to investigate the influence on hydraulic acoustic wave were conducted using pressure swirl atomizer under making frequency range from 0 to 60Hz using water as a propellant. Pressure oscillation from hydraulic sources gives a strong influences on atomization and mixing processes. The ability to drive these low frequency pressure oscillations makes spray characteristics changeable. The effect of pressure perturbation and its spray characteristics showed that low injector pressure with pressure pulsation gives more significantly than high injector pressure with pressure perturbation in SMD, spray cone angle, breakup length. Moreover, this data could be used for prediction of low combustion instability getting G factor.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.394-402
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• 2009

To investigate the heavy-weight impact noise of apartment houses, numerical analysis was performed. The analysis acoustic pressure consider acoustic mode by finite element method. The variables considered effecting on the acoustic pressure are the Acoustic mode, acoustic damping, and the impulse load. The heavy-weight impact noise is a changeable value in the room. Since the most part of the frequency component of heavy-weight impact noise has low frequency. The noise in low frequency is related to the vibration of structure, the reflection of acoustic wave caused by wall and the standing wave called by acoustic mode. The prediction by the numerical analysis was verified with test result of the heavy weight-impact noise at apartment houses.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.265-267
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• 2003

The wavelet transform(WT) has been extensively applied in solving many problems in applied science and engineering following its introduction in early 1980's. The WT analyzes a signal in a changeable frequency range by employing a moving window whereby along time window is used to obtain low frequency information and short time window is used to obtain high frequency information. In this paper, after various fault types in 154 KV transmission system was simulated by using EMTP, and the RMS values by changing Mother wavelet was calculated by applying wavelet transform to the simulated voltage and current signal.

• 한국통신학회논문지
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• 제14권4호
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• pp.338-347
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• 1989

본 논문에서는 종래의 위상누적방식을 이용한 디지털 주파수합성기의 성능을 향상시키기 위해, 클럭주파수합성방식의 디지털 주파수합성기를 설계하고 제작하였다. 고정된 시스템 클럭주파수를 가지고 위상초기치를 가변, 누적시키는 위상 누적방식과는 달리, 클럭주파수 합성방식에서는 PLL을 사용하여 클럭주파수를 가변합성하였고, 이를 N진 계수기의 입력으로 사용하여 고정된 위상 누적치를 갖게 하였다. 성능실험결과 기존의 위상누적방식에서 나타났던 주기적인 출력왜곡현상이 발생하지 않게되어,양자화 불요잠음의 발생이 줄어들었으나, 위상누적방식보다 동일한 설계조건에서 출력대역폭이 계수기의 계수상태에 반비례하여 좁아졌고, PLL을 사용하기 때문에 회로구성이 복잡해졌다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권5호
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• pp.1610-1629
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• 2021

Failures frequently occurred in manufacturing machines due to complex and changeable manufacturing environments, increasing the downtime and maintenance costs. This manuscript develops a novel deep learning-based method named Multi-Domain Convolutional Neural Network (MDCNN) to deal with this challenging task with vibration signals. The proposed MDCNN consists of time-domain, frequency-domain, and statistical-domain feature channels. The Time-domain channel is to model the hidden patterns of signals in the time domain. The frequency-domain channel uses Discrete Wavelet Transformation (DWT) to obtain the rich feature representations of signals in the frequency domain. The statistic-domain channel contains six statistical variables, which is to reflect the signals' macro statistical-domain features, respectively. Firstly, in the proposed MDCNN, time-domain and frequency-domain channels are processed by CNN individually with various filters. Secondly, the CNN extracted features from time, and frequency domains are merged as time-frequency features. Lastly, time-frequency domain features are fused with six statistical variables as the comprehensive features for identifying the fault. Thereby, the proposed method could make full use of those three domain-features for fault diagnosis while keeping high distinguishability due to CNN's utilization. The authors designed massive experiments with 10-folder cross-validation technology to validate the proposed method's effectiveness on the CWRU bearing data set. The experimental results are calculated by ten-time averaged accuracy. They have confirmed that the proposed MDCNN could intelligently, accurately, and timely detect the fault under the complex manufacturing environments, whose accuracy is nearly 100%.