• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.3243-3244
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• 2000

From ancient times, the diagnosis method of the oriental medicine has been performed by curing diseases by means of rectifying and adjusting the unbalance in the physiological function of the five viscera and the six bowels of a human body. Diseases have been diagnosed by the condition of blood circulation that cycles a human body through blood vessels by dint of the vitality of the heart. Based on such a systematic pulse diagnosis method, the article presents parameters that will be beneficial to clinical application on the basis of its analysis of the filtering for eliminating noises from pulse signals inputted from sensor group, the digital hardware dealing with signals necessary for recognition algorithm, and the structure of diagnosis algorithm and components of pulse waveform.

• 센서학회지
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• 제17권6호
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• pp.447-453
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• 2008

Respiration rate is one of the important vital signs. Photo-plethysmography (PPG) measurement especially on a finger has been widely used in pulse oximetry and also used in estimating respiration rate. It is well known that PPG contains respiration-induced intensity variation (RIIV) signal. However, the accuracy of finger PPG method has been controversial. We introduced a new technique of enhancing motion artifact by respiration. This was achieved simply by measuring PPG on the thorax. We examined the accuracy of these two PPG methods by comparing with two existing methods based on thoracic volume and nostril temperature changes. PPG sensing on finger tip, which is the most common site of measurement, produced 6.1 % error. On the other hand, our method of PPG sensing on the thorax achieved 0.4 % error which was a significant improvement. Finger PPG is sensitive to motion artifact and it is difficult to recover fully small respiratory signal buried in waveform dominated by absorption due to blood volume changes. Thorax PPG is poor to represent blood volumes changes since it contains substantial motion artifact due to respiration. Ironically, this inferior quality ensures higher accuracy in terms of respiration measurement. Extreme low-cost and small-sized LED/silicon detector and non-constrained reflection measurement provide a great candidate for respiration estimation in ubiquitous or personal health monitoring.

• 조명전기설비학회논문지
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• 제23권6호
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• pp.96-103
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• 2009

신 재생에너지원은 풍력, 태양 광, 연료전지가 대표적이다. 그러나 고속도로 또는 도로변에서 자동차의 바퀴와 도로 바닥과의 마찰로부터 발생하는 마찰 소음 역시 전기를 발생시킬 수 있는 재생에너지원으로 사료되어 다양한 재생에너지원의 개발 차원에서 연구하게 되었다. 자동차의 차종(중량), 속도, 이격거리 등에 따른 소음의 크기와 파형의 차에 따라 전기에너지의 발생량에 영향을 주었다. 고속도로에서 트럭이 시속 100[km], 측정거리 6[m]에서 최대전압 0.53[V], 최대출력 0.028[W]의 전기에너지를 얻었다.

• 센서학회지
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• 제27권6호
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• pp.421-426
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• 2018

To develop a piezoelectric inkjet printhead for high-resolution and high-speed printing, we studied the characteristics of an inkjet printhead by analyzing the major design parameters. An analytical model for the inkjet printhead was established, and numerical analysis of the coupled first-order differential equation for the defined state variables was performed using state equations. To design the dimension of the inkjet printhead with a driving frequency of 100 kHz, the characteristics of the flow rate and discharge pressure of the nozzle were analyzed with respect to design variables of the flow chamber, effective sound wave velocity, driving voltage, and voltage waveform. It was predicted that the change in the height of the flow chamber does not significantly affect the Helmholtz resonance frequency and discharge speed of the nozzle. From the analysis of change in flow chamber width, it is observed that as the width of the flow chamber increases, the ejection speed greatly increases and the Helmholtz resonance frequency decreases considerably, thereby substantially affecting the performance of the inkjet printhead.

• Transactions on Electrical and Electronic Materials
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• 제14권4호
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• pp.211-215
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• 2013

Partial discharge diagnosis techniques using ultra high frequencies do not affect load movement, because there is no interruption of power. Consequently, these techniques are popular among the prevention diagnosis methods. For the first time, this measurement technique has been applied to the GIS, and has been tested by applying an extra high voltage switchboard. This particular technique makes it easy to measure in the live state, and is not affected by the noise generated by analyzing the causes of faults ? thereby making risk analysis possible. It is reported that the analysis data and the evaluation of the risk level are improved, especially for poor location, and that the measurement of Ultra high frequency (UHF) partial discharge of the real live wire in industrial switchgear is spectacular. Partial discharge diagnosis techniques by using the Ultra High Frequency sensor have been recently highlighted, and it is verified by applying them to the GIS. This has become one of the new and various power equipment techniques. Diagnosis using a UHF sensor is easy to measure, and waveform analysis is already standardized, due to numerous past case experiments. This technique is currently active in research and development, and commercialization is becoming a reality. Another aspect of this technique is that it can determine the occurrences and types of partial discharge, by the application diagnosis for live wire of ultra high voltage switchgear. Measured data by using the UHF partial discharge techniques for ultra high voltage switchgear was obtained from 200 places in Gumi, Yeosu, Taiwan and China's semiconductor plants, and also the partial discharge signals at 15 other places were found. It was confirmed that the partial discharge signal was destroyed by improving the work of junction bolt tightening check, and the cable head reinforcement insulation at 8 places with a possibility for preventing the interruption of service. Also, it was confirmed that the UHF partial discharge measurement techniques are also a prevention diagnosis method in actual industrial sites. The measured field data and the usage of the research for risk assessment techniques of the live wire status of power equipment make a valuable database for future improvements.

• 전자공학회논문지CI
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• 제44권4호통권316호
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• pp.28-35
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• 2007

최근 중요한 매핑기술이 된 LiDAR(Light Detection And Ranging)는 다른 수치표고자료 획득 기법에 비해 높은 정확도와 세밀한 밀도를 가지고 있어 3차원 모델링에 필요한 높이정보를 제공한다. 이러한 시스템의 가장 중요한 작업은 디지털화된 리턴 펄스의 모양을 이해하여 수신권내의 반사되어 오는 시간을 측정하여 이와 대응되는 표면 위치를 계산하고 이를 지리좌표와 연결시키는 것이다. 디지털화된 파형(waveform)은 수신권내의 지표 형태에 따라 다른데 처음 발생된 펄스와 같은 단일 모드이거나 수신권내에 여러 표면이 있는 경우 각 반사 표면에 해당하는 여러 모드로 구성된 복잡한 파형일 수 있다. 자료처리 과정에서 반사표면에 대해 일관성 있는 거리측정 지점을 찾기 위해서는 리턴 파장에서 각 모드의 중심위치나 피크 진폭의 위치를 찾아내는 방법이 필요하다. 복잡한 파장의 경우에는 여러 개의 반사지점에 대해 정확한 높이를 계산해 내는 것이 쉽지 않은데 이를 위해 각 모드가 수신권내의 반사 표면에서 레이저 에너지가 반사되는 분포를 나타낸다고 가정하고 리턴 파장을 각 구성 모드로 분해하는 방법이 제안되었다. 이때 분석을 단순화하기 위해 레이저 출력 펄스 모양이 가우시안 분포를 따른다고 가정하고 전체 리턴 파장을 다변량 가우시안(multivariate Gaussian) 분포를 이용하여 분석한다. 여기서는 혼합분포에서 정확한 피크 위치와 half-width와 같이 모형의 파라미터에 대한 추정치를 구하기 위해 EM 알고리즘을 적용하여 MLE 값을 구하였다. 그러나 실제 레이저 고도계에서 얻어진 데이터는 가우시안이 아닌 오른쪽으로 기울어진 분포를 보여주고 있어 응용분야에 따라 정확한 분석이 필요한 경우 이러한 펄스 모양을 고려한 방법이 필요하다. 본 연구에서는 이러한 펄스 모양을 처리하기 위한 새로운 방법론이 제시되어 있다.

• 한국정보통신학회논문지
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• 제24권5호
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• pp.646-654
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• 2020

이 논문은 강수의 공간분포를 측정할 수 있는 전자파 기반 센서를 개발하는 것이며, 악천후 관측의 핵심인 강우, 강설, 바람장을 동시 측정할 수 있는 전파강수계(EWRG, Electromagnetic Wave Rain Gauge)에 관한 것이다. 본 연구를 통해 LFM 방식의 송수신 신호를 이론적으로 분석하였다. 또한 전파강수계 송수신기를 개발하기 위해서 LFM 송수신기 설계 및 모의실험을 수행하였다. 본 논문은 소형 HMIC(Hybrid Microwave Integrated Circuit)를 사용하여 K-BAND 펄스 구동 형 6W SSPA(Solid State Power Amplifiers) 송수신기 개발을 하였다. 65도의 고온의 환경에서 1%의 짧은 Duty를 가지는 6W 이상의 출력파워, 5dB이하의 수신 NF(Noise Figure)를 가지고 있다. 제작된 모듈은 파형발생부가 내장되어 LFM과 Square Pulse파형을 방출하며 수신부는 40dB이상의 수신 이득을 가진다. 이 논문에서 개발된 송수신기는 다른 소형 기상 레이더에 적용할 수 있다.

• 센서학회지
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• 제16권1호
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• pp.24-32
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• 2007

Conductive rubber material was molded in a belt shape to measure respiration. Its resistivity was approximately $0.03{\;}{\Omega}m$ and the resistance-displacement relationship showed a negative exponent. The temperature coefficient was approximately $0.006{\;}k{\Omega}/^{\circ}C$ negligible when practically applied on the abdomen. The conductive rubber belt was applied on a normal male's abdomen with the dimensional change measured during resting breathing. The abdominal signal was differentiated ($F_{m}$) and compared with the accurate standard air flow rate signal ($F_{s}$) obtained by pneumotachometry. $F_{m}$ and $F_{s}$ differed in waveform, but the start and end timings of each breaths were clearly synchronized, demonstrating that the respiratory frequency could be accurately estimated before further processing of $F_{m}$. $F_{m}-F_{s}$ loop showed a nonlinear hysteresis within each breath period, thus 6 piecewise linear approximation was performed, leading to a mean relative error of 14 %. This error level was relatively large for clinical application, though customized calibration seemed feasible for monitoring general variation of ventilation. The present technique would be of convenient and practical application as a new wearable respiratory transducer.

• 한국전자통신학회논문지
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• 제14권6호
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• pp.1257-1264
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• 2019

기존의 Cuff 기반의 혈압(Blood Pressure)측정 방법은 연속적인 실시간 혈압측정에는 한계를 갖는다. 이러한 이유로 ECG와 PPG 센서 신호를 상호융합한 다양한 혈압추정이 이루어졌다. 그러나 PPG 중심에 측정기법은 AC 노이즈, 작은 맥동, 비박동 등의 많은 문제를 지니고 있다. 본 논문은 ECG와 PPG 관계에 발생하는 맥파전달시간(PTT)과 맥파속도(PWV)를 이용하여 혈압을 추론기법이다. 신호 피크를 이용하는 HRF(Height Ratio Features)에 비해, 본 제안방식은 ECG, PPG의 최고점 혹은 최저점을 사용한 시차를 이용해 추정하기 때문에 PPG 센싱 시그널의 오류에도 안정적인 추출이 가능한 장점이 있다. 본 논문에서 제안 방법을 이용하여 25만 회의 혈압측정의 결과 ±28.5%의 정확도를 갖는 혈압 추정기법을 제시할 수 있었다.

• 한국군사과학기술학회지
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• 제18권2호
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• pp.115-124
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• 2015

A methodology is proposed to estimate a trajectory of a flying target and its velocity using the time and frequency analysis of the acoustic signal. The measurement of sound emitted from a flying acoustic source with a microphone above a ground shall receive both direct and ground-reflected sound waves. For certain frequency contents, the destructive interference happens in received signal waveform reflected path lengths are in multiple integers of direct path length. This phenomenon is referred to as the acoustical mirror effect and it can be observed in a spectrogram plot. The spectrogram of acoustic measurement for a flying vehicle measurement shows several orders of destructive interference curves. The first or second order of curve is used to find the best approximate path by using nonlinear least-square method. Simulated acoustic signal is generated for the condition of known geometric of a sensor and a source in flight. The estimation based on cepstrogram analysis provides more accurate estimate than spectrogram.