• 한국항해항만학회지
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• 제29권4호
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• pp.341-347
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• 2005

A unique technique to extract the phase in time domain is proposed in order to measure the time parameters such as speed and depth by transmitting sound and electric waves. In the signal analysis processing, the phase of pulse signal can be transformed and digitalized with local data in real time without the effect of direct current bias and Nyquist limits. This method is sensitive to base frequency of pulse signal with high spacial resolution and is effective to compare two signals which have different forms. It is expected that the phase analysis technique will be applied to the measurement of the speed and depth accurately by ultrasonic pulse signal in water.

• 전기의세계
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• 제18권1호
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• pp.15-23
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• 1969

A lot of recent researches have shown that a Pseudo Random Binary Signal is a quite effective test signal to measure the impulse response of a plant. Generally speaking, however, such a response itself is not satisfactory to determine the appropriate control parameters or control inputs. Here, the author intends to estimate the unknown parameters of the First Order Plant with Dead Time by means of correlation method using M-sequence signal. The time constant T and the dead time L of the plant are eatimated with one tracking loop by automatically adjusting delay time .tau. of M-sequence signal according to variations of T and L. In this paper, a three level M-sequence signal is used as a test signal in order to avoid troublesome operations to calculate partial derivatives of a given performance index with respect to the parameters which are usually required in the Model Method. Several experiments with analogue computer using low pass filters as averaging circuits showed good results as expected.

• Journal of the Korean Statistical Society
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• 제23권2호
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• pp.403-420
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• 1994

An economic design of the $\bar{X}-R$ chart using variable sample size (VSS) scheme is proposed in this paper. In this design the sample size at each sampling time changes according to the values of the previous two sample statistics, sample mean and range. The VSS scheme uses large sample if the sample statistics appear near inside the control limits and smaller sample otherwise. The set of process parameters, such as the sampling interval, control limits and the sample sizes, are chosen to minimize the expected cost per hour. The efficiency of the VSS scheme is compared to the fixed sample size one for cases where there is multiple of assignable causes. Percent reductions of the expected cost in the VSS design are calculated for some given sets of cost parameters. It is shown that the VSS scheme improves the confidence of the procedure and performs statistically better in terms of the number of false alarms and the average time to signal, respectively.

• 천문학논총
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• 제20권1호
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• pp.109-116
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• 2005

When we measure a source signal in the presence of a background rate that has been independently measured, the usual approach is to obtain an estimate of the background rate by observing an empty part of the sky, and an estimate of the source signal plus background rate by observing the region where a source signal is expected. The source signal rate is then estimated by subtracting the background rate from the source signal plus background rate. However, when the rates or their observation times are small, this procedure can lead to negative estimates of the source signal rate, even when it should produce a positive value. By applying the Bayesian approach, we solve the problem and prove that the most probable value of source signal rate is zero when the observed total count is smaller than the expected background counts. It is also shown that the results from the conventional method is consistent with the most probable value obtained from the Bayesian approach when the source signal is large or the observation time is long enough.

• 한국안전학회지
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• 제23권4호
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• pp.90-98
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• 2008

Presently, pedestrian's signal time models in korea are not considering Vulnerable-Pedestrian. So, the safety of Vulnerable-Pedestrian is being threatener and the number of accidents is increasing. Besides, the existing operational system for pedestrians can't offer the cross signal time in road corresponded the changing environment when the school zone is revitalized and the Silver zone is introduced for Vulnerable-Pedestrian. Conclusively, Vulnerable-Pedestrian's signal time models which are able to consider classified Vulnerable-Pedestrian speed, Vulnerable-Pedestrian perception-reaction time, Vulnerable-Pedestrian Spare(congestion-delay) time are suggested by the result of experiment in virtual crosswalk. the application of suggested models in this study to the site. It is possible to use as a basic stuff on study of pedestrian's signal time and expected to contribute the safety and mobility in future.

• 대한기계학회논문집A
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• 제30권9호
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• pp.1154-1159
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• 2006

In this paper, time-frequency analysis and multi-dimensional spectral analysis methods are applied to source identification and diagnostic of non-stationary sound vibration signals. By checking the coherences for concerned time, this simulation is very well coincident to expected results. The proposed method analyzes the signal instantaneously in both time and frequency domains. The MDSA (Multiple Dimensional Spectral Analysis) analyzes the signal in the plane of instantaneous time and instantaneous frequency at the same time. And it was verified by using the 1500cc passenger car which is accelerated from 70Hz to 95Hz in 4 seconds, the proposed method is effective in determining the vehicle diagnostic problems.

• 한국ITS학회 논문지
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• 제21권4호
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• pp.18-29
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• 2022

주도로 차량 위주의 좌회전감응신호운영은 보행대기시간은 더 늘어날 수 있기 때문에 이는 보행자의 불편 또는 스트레스를 유발하고 있는 실정이다. 따라서 본 연구에서는 좌회전감응신호 적용 전·후의 보행대기시간과 설문조사를 통해 보행자가 느끼는 스트레스를 살펴보았으며 이를 개선하기 위하여 보행자우선 감응신호 시뮬레이션(VISSIM) 분석을 하였다. 좌회전감응신호 적용 후 보행대기시간은 비첨두시간에 37% 증가했다. 설문 결과 보행대기시간이 길어졌다가 62.1%, 그 중 78%는 그로 인하여 스트레스를 받는거로 나타났다. 한편 보행자우선 감응신호 시뮬레이션(VISSIM) 분석 결과, 차량 통행속도는 1.07km/h(2.5%)로 소폭 감소한 반면 보행 평균대기시간은 15.51초(28%) 감소하여 크게 개선되었다. 따라서 보행자우선 감응신호는 보행 대기시간을 감소시켜 보행자 스트레스를 완화할 수 있을 것으로 기대한다.

• Journal of Positioning, Navigation, and Timing
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• 제3권3호
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• pp.99-105
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• 2014

A graphic processing unit (GPU) can perform the same calculation on multiple data (SIMD: single instruction multiple data) using hundreds of to thousands of special purpose processors for graphic processing. Thus, high efficiency is expected when GPU is used for the generation and correlation of satellite navigation signals, which perform generation and processing by applying the same calculation procedure to tens of millions of discrete signal samples per second. In this study, the structure of a GPU-based GNSS simulator for the generation and processing of satellite navigation signals was designed, developed, and verified. To verify the developed satellite navigation signal generator, generated signals were applied to the OEM-V3 receiver of Novatel Inc., and the measured values were examined. To verify the satellite navigation signal processor, the performance was examined by collecting and processing actual GNSS intermediate frequency signals. The results of the verification indicated that satellite navigation signals could be generated and processed in real time using two GPUs.

• International Journal of Quality Innovation
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• 제2권2호
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• pp.136-144
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• 2001

The Markov Chain approach is used to develop an economic adjustment model of a process whose quality can be affected by a single special cause, resulting in changes of the process mean by incorrect adjustment of the process when it is operating according to its capability. The $\bar{X}$ control chart is thus used to signal the special cause. It is demonstrated that the expressions for the expected cycle time and the expected cycle cost are easier to obtain by the proposed approach than by adopting that in Collani, Saniga and Weigang (1994). Furthermore, this approach would be easily extended to derive the expected cycle cost and the expected cycle time for the case of multiple special causes or multiple control charts. A numerical example illustrates the proposed method and its application.

• 전기학회논문지
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• 제62권6호
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• pp.756-761
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• 2013

This paper propose the new demodulation method that can detect resolver signal's peak at the time of position estimation when the position information is required during current controller period. The proposed method is performed in a synchronous demodulation way with exciting signal and also cover a capability which can compensate the lag element of exciting signal caused by the resolver's inductive component and filter circuit. This paper carried out the experiment to investigate the validity and performance of the suggested method by using the test board made up of DSP and demodulation circuit. The test results show that the proposed method is theoretically clear and work completely as expected from making sure of sampling resolver signal's peak at the time of position estimation. In addition, Software position tracking algorithm is executed with the demodulated signals generated by the suggested method and an exact position can be estimated.