• Journal of Biomedical Engineering Research
• /
• v.22 no.2
• /
• pp.133-138
• /
• 2001

동맥계에서 맥파의 전달속도는 혈관의 긴장도에 따라 결정된다. 동맥혈관의 긴장도는 혈압에 의존적이며 순간적인 혈압의 증가에 따른 혈관긴장도의 변화는 순환기계의 질병을 야기할 수 있다. 본 연구에서는 말초맥파를 이용한 동맥 긴장도 평가 방법의 유용성을 밝히기 위하여 말초맥파 도달시간을 체위에 따라 측정하고, 체위 변화에 따른 정수압 변화와 말초맥파도달시간의 관계를 관찰하였다. 말초맥파도달시간의 측정은 심전도의 QRS파 피크로부터 말초에서 나타나는 광전용적맥파의 최대기울기점까지 시간을 측정하였다. 생체 신호를 아날로그-디지털 변환하여 PC에서 매번 심장주기마다 맥파도달시간을 분석하였으며 결과는 스플라인 보간법을 사용하여 그래프로 결과를 제시하였다. 소프트웨어는 C＋＋을 사용하여 windows 환경에서 운용하였다. 앙아위에서 말초맥파도달시간은 233.38$\pm$1.84 ms이었으며 서있는 자세에서는 226.77$\pm$2.16 ms로 유의하게 감소하였다. 앙아위의 자세에서 손을 수직으로 들어올림에 따라 말초맥파도달시간은 각도에 비례하여 증가하는 특성을 보였다. 이러한 실험결과는 말초맥파도달시간이 동맥계의 일시적인 압력 변화에 매우 민감하게 반응하는 것을 제시하였으며, 고혈압 및 동맥경화가 있는 환자에서 예후를 판단하는 방법으로 유용하게 사용될 것이라 사료된다.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2012.05a
• /
• pp.749-750
• /
• 2012

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.69-72
• /
• 2011

The ground tests of the dual pulse solid rocket motors(SRM) were performed to prove the performance of the developed dual pulse solid rocket motors. To achieve dual pulse, pulse seperation device(PSD) and independent ignition systems were installed between the 1st pulse motor and the 2nd pulse motor. The three major development goals are as follow. First, the total impulse of the dual pulse SRM must be over 90% of the single SRM which has same envelopment and weight. Second, the ignition of the 2nd pulse motor can be started at any time between 0 and 60 seconds after termination of the 1st pulse motor. Last, the rupture disk of PSD must not be broken at the 1st pulse pressure, but be broken at below 30% of the 2nd pulse operating pressure. The results of the ground tests satisfied the development goals.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.2 no.3
• /
• pp.209-216
• /
• 2014

One of the widely used NDT(Non-destructive techniques) is the ultrasonic pulse velocity (USPV) method, which determines the travel time of the ultrasonic pulse through the tested materials and most studies were focused on the results expressed in time domain. However, the signal of ultrasonic pulse in time domain can be transformed into frequency domain, through Fast fourier transform(FFT) to give more useful informations. This paper shows a comparison of changes in the pulse velocity and frequency domain signals of concrete for various load histories using lightweight fine aggregates. The strength prediction equation for normal concrete using USPV cannot be used to estimate lightweight fine aggregate concrete strength. The signals in frequency domain of ultrasonic pulse of lightweight fine aggregate concrete does not show any significant difference comparing with those of normal concrete. The increases in stress levels of concrete change the pulse velocities and maximum frequencies, however the apparent relationship between themselves can not be found in this experiment.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.10 no.1
• /
• pp.49-59
• /
• 2011

Recently, ToA and TDoA estimation are favorable among all of estimation techniques because they have the best accuracy in estimating position. ToA and TDoA estimation are typical techniques based on time. So, it is important to have the time syncronization and offset between a target node and several reference nodes. If they don't have the time syncronization between a reference node and target node or have a time offset among reference nodes, the positioning error will increase due to the ranging error. The conventional positioning algorithm does not have a accurate device's position because ranging error is added the calc dation of the position. In this paper, we propose a hybrid method of ToA and TDoA ll increase due. We use MHP pulse that has orthogonal pulse instead of the existing pulse to transmit and receive pulses between a target node and reference nodes. We can estimate the target node's position by ToA and TDoA estimation to transmit and receive MHP pulses only once. When the proposed Hybrid method iteratively calculate the distance, we can select the ranging technique to have more accurate position. The simulation results confirm the enhancement of the Hybrid method.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2012.05a
• /
• pp.341-341
• /
• 2012

최근 기후변화로 인한 이상호우의 발생으로 도시유역에서의 홍수피해가 급증하고 있으며 이로 인해 도시유역에서의 설계홍수량 산정이 매우 중요시 되고 있다. 지금까지는 도시유역에서의 설계홍수량을 산정하기 위해 I-D-F 곡선을 이용하고 있으나 현실적으로 시간단위 이하의 관측강우량 자료의 부족으로 인해 신뢰성 있는 시간단위 이하의 설계강우량 산정에 많은 불확실성을 지니고 있다. 도시유역의 경우에는 자연유역에 비해 강우발생시 일반적으로 도달시간이 한 시간 이하이기 때문에 극한 강우사상 즉, 단시간에 집중적으로 많은 양의 강우가 발생 할 경우 시간단위 이하의 강우강도를 이용한 유출해석이 필요하다. 따라서 본 연구에서는 추계학적 강우발생기법을 통해 시간단위 강우시계열자료를 확충한 후 분해기법을 통해 시간단위이하강우를 생성하였다. 이를 위해 Bartlett-Lewis rectangular pulse 모형과 Cascade 분해 기법을 이용하여 5분단위 강우량자료를 모의발생 하였다. 또한 모의치와 관측치를 재현기간별로 비교, 분석하여 그 차이를 확인하였다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.14 no.5
• /
• pp.472-485
• /
• 1989

This paper represents the occurrence structure of the timing variation of TV horizontal synchronizing pulse(H-sync pulse) in mobile TV reception. Fluttering ghost is caused by timing varations of the H-sync pulse and is due to frequency elective fading in a multipath propagation envoronment. H-sync timing fluctuations, and hence, fluttering ghost are directly correlated with the multipath parameters, i.e., H-sync timing fluctuations reflect well the severity of the multipath environment. The occurrence structure of H-sync timtng fluctuation is analysed theoretically in relation to the multipath environnment. The occurrence structure of H-sync timing fluctuation is analysed theoretically in relation to the multipath parameters, assuming the two-ray propagation model. The H-sync timing fluctuation occurs with the variation in relative phase and /or D/U variation of long-delayed multipath waves.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.10 no.3
• /
• pp.179-184
• /
• 2010

In this paper, we analyze and simulate the performance of RAKE receiver for ultra wide band (UWB) systems in indoor multipath radio channel. Pulse position modulation-time hopping (PPM-TH) signal is considered. And we also consider three types of RAKE receivers, which are ideal RAKE, selective RAKE, and partial RAKE receivers. The indoor channel is modeled as the modified Saleh and Valenzuela (SV) model which has been proposed as a UWB channel model by the IEEE group, IEEE 802.15.SG3a.

• Journal of Convergence for Information Technology
• /
• v.11 no.11
• /
• pp.17-22
• /
• 2021

Radar signal analysis of electronic warfare is a technique for identifying a radar type by signal parameters(direction, radion frequency, pulse repetition interval, pulse width, scan period..) extracted from a received radar pulse. However as the modern radar and new threat environments is advanced, radar identification ambiguity arises in the process of identifying the types of radars. In this paper, we analyze the problems of the existing method and propose a new method. This technique determines the validity of the scan period by the difference in the arrival time of the radar pulse and the minimum number of scan period discrimination. Experiments proved that the scan cycle results are derived regardless of the RMS((Root Mean Square) of the input amplitude.

• Journal of IKEEE
• /
• v.9 no.2 s.17
• /
• pp.115-122
• /
• 2005

We report 400 femto-second highly stable, nearly transform-limited, pulse generation at 10 GHz in $1540{\sim}1550$ nm wavelength region by adiabatic soliton pulse compression of an actively mode-locked fiber ring laser output. Without using any supermode selection device, supermode beating noise has been suppressed below -123 dB/Hz, resulting less than 100 femto-second timing jitters at the noise band of $1\;kHz{\sim}100\;MHz$.