• Nuclear Engineering and Technology
• /
• 제36권1호
• /
• pp.12-23
• /
• 2004

In the present study a new measurement technique has been developed, which uses an ultrasonic transmission signal in order to identify the vertical two phase flow pattern. The ultrasonic measurement system developed in the present study not only provides the information required for the identification of vertical two phase flow patterns but also makes real time identification possible. Various vertical two phase flow patterns such as bubbly, slug, churn, annular flow etc. have been accurately identified with the present ultrasonic measurement system under atmospheric condition. In addition, the present test apparatus can practically simulate the ultrasonic propagation characteristics under high temperature and high pressure systems. Therefore, it is expected that the present ultrasonic flow pattern identification technique could be applicable to the vertical two phase flow systems under high temperature and high pressure conditions.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 제38회 하계학술대회
• /
• pp.87-88
• /
• 2007

An acoustic total or partial enclosure is widely used to reduce the sound pressure level propagating from a noise source. However, the performance of the acoustic enclosure is decreased by its inherent limitations such as temperature rise or acoustic pressure build-up inside the enclosed acoustic field. In this reason, an acoustic enclosure consisting of a silencer and absobent panels with acoustic resonators is studied to reduce the transmitted noise from a transformer. Large sound-attenuation is expected by applying the enclosure to the large transformers in a substation.

• 한국기계기술학회지
• /
• 제13권4호
• /
• pp.117-124
• /
• 2011

A gear pump is a type of pump that displaces a volume of fluid by physical or mechanical action, or positive displacement pump. Power is applied to one of the gears and transmitted to a second driven gear via meshing teeth. This paper describes the hydraulic gear pump for an elevator. In gear pump, since geometrically special forms of gear tooth, 'Pulsations' is always caused in the delivery pressure and quantity. In other words, it is found that the number of delivery pressure pulsation per each revolution is always equal to that of the gear-teeth of the gear, which is coincident with the pulsation of the ideal delivery quantity. Some experimental results are given to verify the effectiveness of the developed pump.

• 대한설비공학회지:설비저널
• /
• 제17권4호
• /
• pp.499-507
• /
• 1988

The pressure suppression pool of BWR(Boiling Water Reactor) is subjected to hydrodynamic impact in the event of a LOCA(Loss of Coolant Accident). The pressure increase in the reactor dry cell would force the existing water of a vent pipe into the suppression pool. When the water is ejected through the pipe opening into the suppression pool, an abrupt downward force is transmitted to the suppression pool floor. Consequently, many structures installed within the pool must be able to withstand these forces. In order to determine the optimum safe locations of the pool structures, numerical analysis have been carried out to investigate the hydrodynamic behavior of the water jet. In the present analysis, a two-dimensional numerical model is utilized to solve transient flow equations.

• 전자공학회논문지
• /
• 제51권1호
• /
• pp.233-240
• /
• 2014

최근 노인인구의 증가하는 추세에 따라 만성질환자의 수도 증가하고 있으며 건강 관리문제가 중요하게 대두되고 있다. 본 논문에서는 만성질환자의 건강관리를 위한 유헬스케어 시스템을 구현하고자 한다. 제안한 만성 질환자 관리 시스템은 생체 계측 시스템과 모바일 게이트웨이 그리고 의료정보 관리 서버 그리고 클라이언트로 구성되면 생체 신호는 심전도, 혈압, 혈당, 산소포화도 등의 모듈로 구성하였다. 혈당체크는 이동성을 고려하여 생체계측 시스템으로 전송하는 방법과 게이트웨이로 전송하는 방법 중 선택할 수 있도록 구현하였다. 제안한 생체 계측 시스템과 모바일 게이트웨이는 블루투스 통신을 이용하여 전송한다. 전송된 생체 데이터는 모바일 게이트웨이에서 건강상태를 감시하거나 네트워크 서버로 전송하고 클라이언트을 이용하여 검색 할 수 있도록 하였다. 만성질환자의 생체신호 감시 시스템을 구현함으로서 측정되어진 생체 데이터를 모니터링하여 현재의 건강상태를 확인할 수 있었으며 모바일 환경에서 다양한 생체신호를 전송하였다.

• 한국음향학회지
• /
• 제6권3호
• /
• pp.17-22
• /
• 1987

새로운 차음성능 측정방법인 표면인텐시티법을 이용하여 실제 건축물의 현장에서 각부위별 차음성능 평가하고. 이를 종래의 음압측정방법과 은향인텐시티법 및 이론계산에 의한 결과 치 와 비교 . 검토하였다. 표면인텐시티법에 의한 건물부위의 차음성능 측정결과치는 음향인 텐시티법 및 이론계산에 의한 결과치와 잘 일치하였으며, 표면 인텐시티법은 음향인텐시티 법과 더불어 종래의 음압측정방법에 비해 측정시 주위 암소음 및 flanking transmission의 영향을 적게 받는 것으로 나타났다.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2008년도 추계종합학술대회 B
• /
• pp.312-315
• /
• 2008

최근 유비쿼터스, RFID 및 근거리 무선통신 기술의 발전에 힘입어 의료분야에서도 이러한 기술을 이용하여 원격지에서 환자의 생체 신호와 각종 의료데이터를 무선으로 측정할 수 있는 시스템에 대한 많은 연구가 이루어지고 있다. 본 논문에서는 심전도(ECG), 혈압, 맥박 등의 생체신호 측정센서를 이용한 센서네트워크를 구축하여 u-Healthcare 시스템을 설계하고 구현하였다. 센서노드에서 게이트웨이를 경유한 생체신호는 헬스케어센터로 전송되며, 헬스케어센터에서 분석한 결과에 따라 환자에게 운동요법, 식이요법 등의 정보를 피드백하여 건강관리를 할 수 있게 하였다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2001년도 하계종합학술대회 논문집(4)
• /
• pp.151-154
• /
• 2001

In this Paper, a new harmonic imaging technique is proposed and evaluated experimentally. In the proposed method, a weighted chin signal with a hanning window is transmitted. The RF samples obtained on each array element are individually compressed by correlating with the reference signal defined as the 2nd harmonic (2f0) component of a transmitted chirp signal generated in a square-law system. The proposed method uses the compressed 2f0 component to form an image, for which the crosscorrelation term with f0 component should be suppressed below at least -60dB. After experiment, the 6dB pulse width and peak sidelobe level of the compressed 2f0 component were 0.7us and -60dB, respectively. This result shows that the proposed method can successfully eliminate the f0 component with a single transmit-receive event and therefore is more efficient than the conventional pulse inversion (PI) method in terms of frame rate. We also observed that the 2nd harmonic compont starts to decrease for source pressure higher than 210kPa in water, which implies that SNR of the 2nd harmonic imaging using short pulses cnanot be incresed beyond a certain limit.

• 전기학회논문지
• /
• 제57권12호
• /
• pp.2300-2307
• /
• 2008

This study receives the noise transmitted in a constant audio frequency range through a microphone array in which the noise(like grease in a pan) occurs on the power supply line due to the troublesome partial discharge(arc). Then by going through a series of signal processing of removing noise, this study measures the distance and direction up to the noise caused by the troublesome partial discharge(arc) and monitors the result by displaying in the analog and digital method. After these, it determines the state of each size and judges the distance and direction of problematic part. When the signal sound transmitted by the signal source of bad insulator is received on each microphone, the signal comes only in the frequency range of 20 kHz by passing through the circuit of amplification and 6th low pass filter. Then, this signal is entered in a digital value of digital signal processing(TMS320F2812) through the 16-bit A/D conversion. By doing so, the sound distance, direction and coordinate of bad insulator can be detected by realizing the correlation method of detecting the arriving time difference occurring on each microphone and the algorithm of detecting maximum time difference.

• 센서학회지
• /
• 제15권2호
• /
• pp.139-147
• /
• 2006

Lower urinary tract symptoms (LUTS) affect self-assessed quality of life. The prevalence of LUTS is commonly high in the elderly. The purpose of urodynamic investigation is to obtain information on the function of the urinary system. One of the most frequently used measurement procedures in urodynamics is filling and voiding cystometry. But in this system transurethral catheter is used and it makes patients uncomfortable. The aim of this study is to implement the system that could evaluate noninvasively the function of urinary tract. A new system has been developed to analyze urine flow rate and vesical pressure during voiding. These signals were recorded simultaneously and transmitted to a PC. For system evaluation, a model for the lower urinary system of men was constructed. From the evaluation of the model, vesical pressure was correlated with the occlusion degree. In a pilot study with five male subjects, maximum of standard deviation was 1.26, error rate was 3.49 and coefficient of variation was 3.48.