• 센서학회지
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• 제26권2호
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• pp.141-147
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• 2017

A pressure sensor in pulse measurement system is a core component for precisely measuring the pulse waveform of radial artery. A pulse sensor signal that measures the pulse wave in contact with the skin is affected by the temperature difference between the ambient temperature and skin surface. In this study, we found experimentally that the signal changes of the pressure sensors and a temperature sensor were caused by the temperature of the wrist surface while the pressure sensor was contacted on the skin surface for measuring pulse wave. To observe the signal change of the pulse sensor caused by temperature increase on sensor surface, Peltier device that can be kept at a set temperature was used. As the temperature of Peltier device was kept at $35^{\circ}C$ (the maximum wrist temperature), the device was put on the pulse sensor surface. The temperature and pressure signals were obtained simultaneously from a temperature sensor and six pressure sensors embedded in the pulse sensor. As a result of signal analysis, the sensor pressure was decreased during temperature increase of pulse sensor surface. In addition, the signal difference ratio of pressure and temperature sensors with respect to thickness of cover layer in pulse sensor was increased exponentially. Therefore, the signal of pressure sensor was modified by the compensation equation derived by the temperature sensor signal. We suggested that the thickness of cover layer in pulse sensor should be designed considering the skin surface temperature.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.181.4-181
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• 2001

In this study, we have developed the digital hardware system which performs signal processing necessary for the filtering to eliminate noises by inputting pulse wave signals from the sensor group. With a view to obtain clinically effective information, we analyzed structural elements of pulse waveform and, thus, conducted a systematic classification. What is more, this study has conducted researches in the web-based diagnosis data management system of pulse waveform as well as the method of transmitting the data of pulse waveform. In order to set the standard for the documents of the pulse ...

• 한국자기학회지
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• 제21권3호
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• pp.104-107
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• 2011

비가압 상태에서 정확하게 측정한 맥진파형 신호를 얻기 위하여 영구자석과 홀소자로 구비된 안정시 휴대성이 가능한 집게형 맥진기 시제품을 개발하였다. 소형 영구 자석 1개 위치 변화로 얻은 요골동맥 맥진 파형의 4가지 중요 상관인자인 주기, 수축시간, 반사파시간, 절흔 시간들을 결정하여 5초간 수집한 실험값들을 서로 비교 분석하였다. 집게의 스프링에서 누르는 일정 압력을 사용해 가압 느낌 없이 재현성 있는 맥박수 및 혈압 측정함으로써 홀소자 집게형 맥진기 개발이 가능함을 보여주었다.

• International Journal of Fluid Machinery and Systems
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• 제6권4호
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• pp.206-212
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• 2013

Self-excited pulse jet is a specific nozzle with a closed chamber which can change a continuous jet into a pulse one. Energy of the pulse jet can be output not only unevenly but also with multifrequency. With the peak pressure of pulse jet, the hitting power would be 2~2.5 times higher than that of continuous jet. In order to reveal the correlation between the self-excited pulse frequency and nozzle diameter ratio, nozzle spacing and operating pressure, the model of 3D unsteady cavitation model has been used. We found that with the same nozzle structure parameters and the different operating pressure, the self-excited frequency and the width of peak crest are different, but the wave profiles are similar. With FFT, we also found that the less bandwidth of amplitude in low frequency range will lead to the wider wave crest of outlet velocity in its time domain, and the larger force of the strike will be gained. By studying the St of self-excite nozzle, not only the frequency of a certain nozzle can be predicted, but also a nozzle structure with a certain frequency can be designed.

• 소음진동
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• 제11권2호
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• pp.241-248
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• 2001

The present paper describes experimental and computational work to augment the magnitude of the impulsive wave. An experiment was performed using a simple shock tube with an open end and numerical calculations were carried out to solve the unsteady, axisymmetric, inviscid, compressible governing equations. The control strategy applied was to alter the exit geometry of a straight tube to a sudden enlargement tube and a flare tube. The effects of the configurations of the tube exit on the magnitude of the impulsive wave were investigated over the range of the weak shock Mach number from 1.01 to 1.10. The results obtained were compared to those of the straight tube tests. The numerical result predicted the magnitude of the experimented impulsive waves with a good accuracy. The present passive control technique enabled the magnitude of the impulsive wave to augment by about 23 percent, compared to that of the straight tube of no control.

• 한국정밀공학회지
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• 제20권3호
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• pp.157-164
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• 2003

The pulse-echo method is one of the most widely used ultrasonic techniques for application of nondestructive evaluation. Particularly, quantitative nondestructive evaluation of defects has been considered more important to assure the reliability and the safety of structure. Frequency energy in adhesive joints is based on the ultrasonic wave analysis. The attenuation coefficient upon wave amplitude and the frequency energy that is expressed in the term of wave pressure amplitude were utilized for the primary wave experiment. By means of a control experiment, it was confirmed that the variation of the frequency energy in adhesive joints depends on transition by stress variation. In this paper, the ultrasonic characteristics were measured for single lap joint and Double Cantilever Beam specimen with different fracture modes that was subjected to stress. Consequently, the data that was obtained from the adhesive specimen was analytically compared to the fracture mechanics parameter

• 대한전기학회논문지:시스템및제어부문D
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• 제55권12호
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• pp.511-517
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• 2006

The key issues in high power, high energy applications such as electromagnetic launchers include safety, reliability, flexibility, efficiency, compactness, and cost. To explore some of the issues, a control scheme for a large current wave-forming was designed, built and experimentally verified using a 2.4MJ pulse power system (PPS). The PPS was made up of eight capacitors bank unit, each containing six capacitors connected in parallel. Therefore there were 48 capacitors in total, with ratings of 22kV and 50kJ each. Each unit is charged through a charging switch that is operated by air pressure. For discharging each unit has a triggered vacuum switch (TVS) with ratings of 200kA and 250kV. Hence, flexibility of a large current wave-forming can be obtained by controlling the charging voltage and the discharging times. The whole control system includes a personal computer(PC), RS232 and RS485 pseudo converter, electric/optical signal converters and eight 80C196KC micro-controller based capacitor-bank module(CBM) controllers. Hence, the PC based controller can set the capacitor charging voltages and the TVS trigger timings of each CBM controller for the current wave-forming. It also monitors and records the system status data. We illustrated that our control scheme was able to generate the large current pulse flexibly and safely by experiments. The our control scheme minimize the use of optical cables without reducing EMI noise immunity and reliability, this is resulting in cost reduction. Also, the reliability was increased by isolating ground doubly, it reduced drastically the interference of the large voltage pulse induced by the large current pulse. This paper contains the complete control scheme and details of each subsystem unit.

• 대한의용생체공학회:의공학회지
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• 제31권4호
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• pp.328-334
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• 2010

Over the past few years, a considerable number of methods have been proposed and applied for the classification of photoplethysmography (PPG). Most of the previous studies, however, focused on the qualitative description of the pulse type according to specific disease and thus provided ambiguous criteria to interpreters. In order to screen out this problem, we present a quantitative method for the pulse type classification including the second derivative of photoplethysmography (SDPTG). In the PPG signal, we have classified the signal as 4 types using the position and the presence of the dicrotic wave. In addition, we have categorized the SDPTG signal as 7 types using the position and the presence of "c" and "d" wave and the sign of "c" wave. In order to check the efficacy of the proposed pulse type classification rule, we collected pulse signals from 155 subjects with different ages and sex. From the correlation analysis, Class 1(p<0.01) and Class 2(p<0.01) in the PPG signal are significantly correlated with ages. In a similar manner Class A(p<0.01), Class C(p<0.05), Class D(p<0.01), and Class F(p<0.01) in the SDPTG signal are considerably correlated with the ages. From these observations, and some earlier ones [4], [5], we can conclude that since the newly proposed method has objectivity and clarity in pulse type classification, this method can be used as an alternative of previous classification rules including similar age-related characteristics.

• Korean Journal of Acupuncture
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• 제33권3호
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• pp.121-130
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• 2016

Objectives : Recently, people who have normal brachial blood pressure(BP) are being threatened by high-risk disease such as stroke. The aim of this study is to suggest that new method to assess systemic circulation. It can be performed by analyzing optimal blood pulse wave on 3 sites belonging to subjects that have normal BP. Methods : We respectively extracted main peaks(h1) of optimal blood pulse wave on left/right temporal artery(LR1=h1), radial artery(LR2=h1) and dorsalis pedis artery(LR3=h1). We obtained h1 from 30 subjects who are discreetly chosen and have normal BP. Main peak(h1) can be extracted by using 3D pulse imaging analyser(DMP-1000+, DAEYOMEDI Co., Korea) that has 5-level pressure method. We analyzed the ratio of [LR1/LR2] and [LR3/LR2]. Results : In the case of male group, the results are [LR1/LR2=0.7100.177] and [LR3/LR2=0.9290.317]. In the case of female group, the results are [LR1/LR2=0.6680.121] and [LR3/LR2=0.7050.195]. Especially, it is statistically verified that the result of ratio [LR3/LR2] is much higher in male group than in female group(p<0.05). Conclusions : We suggested the standard ratio of [LR1/LR2] and [LR3/LR2] for normal subjects, respectively. It can be adopted as a new method to evaluate the systemic circulation.

• 한국자기학회지
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• 제23권4호
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• pp.135-143
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• 2013

요골 동맥의 중앙 부에 위치 한 "관"이란 곳에 영구자석 부착하여 맥의 움직임에 따라 발생하는 자기장의 변화를 홀센서로 정량화하여 맥진파형을 측정하는 집게형 맥진기를 개발하였다. 홀소자 맥진센서로 얻어진 전기적 신호로 심전도와 용적맥파계를 사용해 동시에 측정된 맥박수, 비침습적 혈압, 호흡수, 맥파전달속도와 공간맥파전달속도를 환자감시장치에 디스플레이하였다. 개발된 장치는 한방과 양방의 의료용 저장 매체와 새롭게 시도되거나 융합되어지고 있는 환자감시 장비 및 유비쿼터스 헬스케어 시스템 개발에 도움이 될 것이다.