• 한국초전도ㆍ저온공학회논문지
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• 제2권1호
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• pp.45-50
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• 2000

The present study has been conducted to observe the heat transfer under pulsating pressure and oscillating flow. The experimental apparatus was fabricated to measure the gas temperature, the wall temperature. the pressure and the instantaneous heat flux inside the pulse tube. The measured gas temperature and heat flux must be calibarated to compensate their finite time constant in the oscillating flow conditious. The experiment was performed from 1 Hz to 5 Hz. The phase difference between the instantaneous heat flux and the gas-wall temperature difference was clearly observed. The experimental heat fluxes were compared to the theroretical correlations such as Complex Nusselt Number Model(CNNM) and Variable Coefficient Model(CVM). The heat flux predisted by CNNM was always greater than that of VCM. The experiment confirmed the valisity of the VCM for the instantaneous heat flux under the pulsating pressure and oscillating flow in the warm end of the pulse tube.

• 동의생리병리학회지
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• 제27권3호
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• pp.313-317
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• 2013

In order to standardize the pressure/depth against radial artery, the externally-applied-pressure measuring system was fabricated and evaluated. Based on the resistance-variable characteristic of the very thin($10{\mu}m$) film conductive tape along the pressure of a tip of a examiner's hand, this system was designed. The change of the pressure was processed through voltage regulator and Matlab S/W, then showed on computer monitor. The signal output through voltage regulator, and Matlab S/W was evaluated on various conditions. The evaluation was executed on these cases; an examiner slowly increases and decreases the pressure, rapidly increases and decreases the pressure, sequentially increases and decreases the pressure, sustains the pressure, micro-changes the pressure. As a pulse examiner varies the pressure on the radial artery of the examinee, the system's real-time output consistently varies according to the pressure. From the results, it is concluded that this system consistently shows the pressure of the tip of a examiner's hand in real time without interrupting the evaluation of the radial artery pulse. Therefore this system is expected to standardize the value of the pressure/depth externally applied by an examiner.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.573-576
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• 1998

In this paper, we devised pulse detection transducer that has non-differential characteristics for pulse detection on chongu arterial. The transducer consist of load cell and driving electronic circuits. Load cell consist of cantilever and two metal film strain gauge. The pressure signal from chongu artery is delivered to load cell using artery rider that attached to cantilever. Therefore the pressure pulse signal can obtain by the developed transducer. As the results of experiment, the developed transducer has a good linearity at pressure to voltage conversion and acan detect non-differential pulse signal from chongu artery.

• 한국환경과학회지
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• 제19권4호
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• pp.437-446
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• 2010

The pressure drop through pulse air jet-type bag filter is one of the most important factors on the operating cost of bagfilter houses. In this study, the pilot-scale pulse air jet-type bag filter with about 6 m2 filtration area was designed and tested for investigating the effects of the four operating conditions on the total pressure drop, using the coke dust collected from a steel mill factory. When the face velocity is higher than 2 m/min, it is not applicable to on-spot due to the increase of power expenses resulting from a high-pressure drop, and thus, 1.5 m/min is considered to be reasonable. The regression analysis results show that the degree of effects of independent parameters is a order of face velocity > concentration > time > pressure. The results of SPSS answer tree analysis also reveal that the operation time affects the pressure drop greatly in case of 1 m/min of face velocity, while the inlet concentration affects the pressure drop in case of face velocity more than 1.5 m/min.

• 센서학회지
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• 제25권2호
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• pp.138-142
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• 2016

A pulse measurement by tonometry provides useful information for diagnosis, including not only blood pressure and heart rate but also parameters for estimating a condition of the cardiovascular system. Currently, various pulse measurement devices based on the tonometry have been developed. A reliability of these devices is determined by a positioning technic between the sensor and the blood vessel and a controlling technique of the pressurization level. An angle of the sensor for the pulse measurement seems to be highly related with a measured signal, however, the objective studies for this issue have been not published. In this paper, the variation of the pulse signals by tonometry direction was experimentally assessed according to the angle of the sensor. In order for guaranteeing the repeatability of the experiment, we used a pulse generator device, which can generate human pulse signal by using silicon tube and fluid pump, and developed a structure for precise adjustment of the angle and the pressurization level of the sensor. The angle of the sensor was acquired by an inclinometer, which was attached at the opposite side of the sensor. As results, a coefficient of variation (CV) of a maximum amplitude (MA) of the pulse wave was largely increased over the angle range of $-9{\sim}9^{\circ}$. Furthermore, the changes of the pulse shape showed different aspects according to the sign of the angle tilted along the blood vessel. It is expected that the results of this study can be helpful for developing more precise pulse measurement devices based on the tonometry and applying in clinic.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1978.1_1979.1
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• 2009

In this paper, we have proposed and demonstrated a tonometry sensor array for measuring arterial pulse pressure. A sensor module consists of 7 piezoresistive pressure sensor array. Wire-bonded connection was provided between silicon chip and lead frame. PDMS(poly-dimethylsiloxane) was coated on the sensor array to protect fragile sensor while faithfully transmitting the pressure of radial artery to the sensor. Tonometric pulse pressure can be measured by this packaged sensor array that provides the pressure value versus the output voltage.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.834-837
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• 2005

In this paper, we describe the method of non-invasive blood pressure measurement using pulse wave transit time(PWTT). PWTT is a new parameter involved with a vascular that can indicate the change of BP. PWTT is measured by continuous monitoring of ECG and pulse wave. No additional sensors or modules are required. In many cases, the change of PWTT correlates with the change of BP. We measure pulse wave using the photo plethysmograph(PPG) sensor in an earlobe and we measure ECG using the ECG monitoring device our made in the chest. The measurement device for detecting pulse wave consists of infrared LED for transmitted light illumination, pin photodiode as light detector, amplifier and filter. We composed 0.5Hz high pass, 60Hz notch and 10Hz low pass filter. ECG measurement device consists of multiplexer, amplifier, filter, micro-controller and RF module. After amplification and filtering, ECG signal and pulse wave is fed through micro-controller. We performed the initial work towards the development of ambulatory BP monitoring system using PWTT. An earlobe is suitable place to measure PPG signal without the restraint in daily work. From the results, we can know that the dependence of PWTT on BP is almost linear and it is possible to monitoring an individual BP continuously after the individual calibration.

• 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.

• 디지털융복합연구
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• 제20권4호
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• pp.411-418
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• 2022

본 연구는 한국 성인의 수면시간과 맥압과의 관련성을 알아보고자 하며, 연구방법은 국민건강 영양조사 제7기(2016-2018) 자료를 이용하였다. 대상자는 20세 이상 5,707명을 대상으로 빈도와 백분율 연속형 자료는 평균과 표준편차, 교차분석과 independent t-test, 고 맥압에 대한 단계적인 로지스틱 회귀분석을 실시하였으며, SPSS WIN 18.0 version 통계프로그램을 이용하였다. 연구결과 전체 인구(OR=1.344, 95% CI=1.002-1.803)와 여성(OR=1.624, 95% CI=1.112-2.371)에서는 수면시간이 6시간 이하에 비하여 9시간 이상에서 고 맥압의 유병률이 높았지만, 남성(OR=1.012, 95% CI=0.631-1.550)에서는 그 유의성이 없었다. 따라서 적절하지 않은 수면시간이 건강에 미치는 영향을 고려할 때 이에 대한 보건학적인 교육과 관리가 필요할 것으로 생각하며 추후 수면시간과 맥압의 관계에 관해서는 계속된 연구가 필요할 것이다.

• 한국환경과학회지
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• 제29권5호
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• pp.457-468
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• 2020

With continuous industrial development, the types, and amount of particulate matter (PM) have been increasing. Since 2018, environmental standards regarding PM have become more stringent. Pulse air jet bag filters are suitable for PM under the 20 ㎛ and, can function regardless of size, concentration and type. Filtration velocity and shape are important factors in the operation and design of the pulse air jet bag filters however, few established studies support this theory. In this research, numerical simulations were conducted based on experimental values and, several methods were employed for minimizing the pressure drop. In the pilot system, as the inlet duct velocity was faster than 19 m/sec, flow was not distributed equally and, re-entrainment occurred due to the hopper directional vortex. The multi-inlet system decelerated the hopper directional vortex by 25 ~ 30%, thereby decreasing total pressure drop by 6.6 ~ 14.7%. The guide vane system blocked the hopper directional vortex, which resulted optimal vane angle of 53°. The total pressure of the guide vane system increased by 0.5 ~ 3% at 1.5 m/min conditions. However, the filtration pressure drop decreased by 4.8 ~ 12.3% in all conditions, thereby reducing the operating cost of filter bags.