• Journal of Digital Contents Society
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• v.11 no.3
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• pp.283-290
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• 2010

The effectiveness of 3.0T phase array coil images was tested by comparing signal-to-noise ratios for the same coil images relative to 1.5T endorectal coil images. Signal intensities were measured in the three regions of prostate, central and peripheral (right and left) after 40 patients with prostate cancer were imaged during the period between Jan. 2008 and Oct. 2009 with T2 W, T1 W, and DW images obtained respectively using endorectal coil on a 1.5T MR scanner and phase array coil on a 3.0T MR scanner. For quantitative analysis, comparisons of average SNRs for the same ROIs were made between groups scanned with a 1.5T and a 3.0T MR scanner. The signal-to-noise ratios were shown to increase more sharply when using a phase array coil at a 3.0T MR scanner compared to using an endorectal coil at a 1.5T MR scanner.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.8
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• pp.1925-1933
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• 2015

RFID based applications that combine radar techniques to obtain the location and the ID of a tag have widely been investigated. In this paper, we analyze a recently proposed RFID system that can extract the tag IDs and their velocities using signals transmitted from the tag attached moving objects and verify its performance. In the proposed system, a beacon transmits triggering signal at regular intervals into a monitoring area and the tag receiving the triggering signal backscatters the FMCW(frequency modulation continuous wave) signal modulated by the tag ID. The reader system demodulates this FMCW signal using predefined two reference signals to obtain not only the tag ID but its velocity. In this paper, we show that the proposed system works properly and analyze the degree of performance degradation in cases when the synchronization error between the transmitting signal and the reference signal occurs, and even when sampling rate is lowered for implementation purpose. Finally, the analytical results are verified by simulation.

• Journal of Advanced Navigation Technology
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• v.17 no.6
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• pp.616-624
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• 2013

When jamming signal is received, there would be malfunctions in GPS-based precise location systems. Especially, in aviation fields, these malfunctions may lead to more serious damages. Naturally, there are some research results about the prevention or location method for one jammer, but it is hard to identify and obtain measurements when multiple and various type signals are received. Therefore, we propose a method of identification and measurements acquisition algorithm in order to localize the multiple jammers which transmit CW, DSSS and SCW type signals. Also, a computer simulation is carried out so as to validate the feasibility of the proposed method by using MATLAB. From the simulation results, it is confirmed that the proposed method successfully identified the signal type and acquired the measurements of CW, DSSS and SCW type signals.

• The Journal of the Acoustical Society of Korea
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• v.22 no.8
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• pp.687-693
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• 2003

In this paper, a new adaptive audio signal enhancement algorithm is proposed. In order to remove a broadband noise from a noisy signal, a filter is designed and applied adaptively to noisy audio signal. The noisy signal is first transformed to frequency domain and divided into bark domain to calculate excitation energy. A filter will be calculated to eliminate the noise by using the excitation energy and noisy energy which is obtained from a silent area. The filter is adaptively adjusted and continuously applied until the threshold point is met. The algorithm also works well even though the noise's energy change all of a sudden. SNR, NMR comparison and MOS Test are performed to show the effectiveness of the proposed algorithm.

• Journal of IKEEE
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• v.10 no.1 s.18
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• pp.62-68
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• 2006

In this paper, we propose an adaptation strategy for blind equalizers, which combines a blind algorithm based on high order statistics and the decision directed LMS algorithm. In contrast to 'Stop-and-Go' algorithm, where adaptation is stopped for unreliable signals, the proposed algorithm applies high order statistics (HOS) blind algorithm to the unreliable signals and applies DD-LMS for the reliable signals. The proposed algorithm, named 'Run-and-Go' algorithm, inherits minimum MSE performance of DD-LMS and acquisition ability of blind algorithms. Furthermore, by updating the reliable signal region according to signal quality in each iteration, the convergence speed and acquisition ability is further improved.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.6
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• pp.654-660
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• 2013

This paper describes an imaging approach to detect targets behind a wall. To acquire the accurate information over the strong signals reflected by the wall and affected by multipath, a bi-static through-wall imaging radar using a noise waveform is proposed in this paper including the methodology of imaging the received signal. The complete derivation of the proposed approach is presented. And the result of tests is demonstrated to show the possibility of the proposed approach.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.169.2-169.2
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• 2012

고기동 위성에 탑재된 GPS 수신기의 위성체의 기준 위치, 속도 및 시간의 정보를 제공한다. 특히 저궤도 관측위성은 빠른 동적 특성으로 인하여 GPS 위성 신호 획득 및 추적이 어려울 경우 연속적인 항행해를 제공하기 어려울 수 있다. 이를 위하여 위성 GPS 수신기는 지상용과 달리 넓은 대역폭의 신호 획득 및 추적이 가능한 RF수신단이 탑재되어 있으며 필터 기반의 궤도전파기가 탑재되어 있어 있다. 뿐만 아니라 GPS 수신기기의 상태 데이터 제공 및 고속 데이터 처리를 위하여 고성능 CPU가 탑재되어 있다. 특히 탑재된 궤도전파기는 고성능 필터 기반으로 설계되어 있으며 이를 이용하면 GPS 신호 추적이 되지 않은 상황에서도 비교적 정확하고 연속적인 항행해가 제공하게 된다. 본 논문에서는 저궤도 관측위성에 탑재된 GPS 수신기가 초기 위성운영에서 어떠한 절차에 의하여 동작이 되며 위성의 빠른 동적 특성에서 GPS 수신기의 가시성 및 추적 위성개수 분석 및 이를 바탕으로 위치 및 속도 정밀도가 어느 정도 되는지에 대한 성능 분석 결과를 정리 하였다. 본 논문 결과는 향후 고기동 위성의 GPS 수신기 및 관련 운영에 도움이 될 것으로 판단된다.

• Journal of the Korean Society of Radiology
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• v.16 no.6
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• pp.697-702
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• 2022

For imaging in positron emission tomography(PET), it is necessary to measure the position of the scintillation pixel interacting with the gamma rays incident on the detector. To this end, in the conventional system, a flood image of the scintillation pixel is obtained, the imaged area of each scintillation pixel is separated, and the position of the scintillation pixel is specified and acquired as a digital signal. In this study, a deep learning method was applied based on the signal formed by the photosensor of the detector, and a method was developed to directly acquire a digital signal without going through various procedures. DETECT2000 simulation was performed to verify this and evaluate the accuracy of position measurement. A detector was constructed using a 6 × 6 scintillation pixel array and a 4 × 4 photosensor, and a gamma ray event was generated at the center of the scintillation pixel and summed into four channels of signals through the Anger equation. After training the deep learning model using the acquired signal, the positions of gamma-ray events that occurred in different depth directions of the scintillation pixel were measured. The results showed accurate results at every scintillation pixel and position. When the method developed in this study is applied to the PET detector, it will be possible to measure the position of the scintillation pixel with a digital signal more conveniently.

• Broadcasting and Media Magazine
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• v.19 no.1
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• pp.56-64
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• 2014

본 고에서는 증강현실 오디오 기술에 대한 연구동향을 소개한다. 특히 증강현실 오디오 실현을 위한 핵심기술이라고 할 수 있는 오디오 객체를 획득하기 위한 단일지향성 및 쌍지향성 마이크로폰을 이용한 마이크로폰 어레이 설계 기술과 오디오 채널간의 신호 강도차 분석을 통한 오디오 객체 획득 기술에 대해 설명한다.

• Proceedings of the KAIS Fall Conference
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• 2009.12a
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• pp.649-651
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• 2009

교통신호제어를 시행하려면 신호 검출을 위험한 곳에서 시행을 한다든지 한계에 부딪히는 곳에서 데이터를 수집를 하는 경우가 대부분이다. 이곳에 sensor node를 배치하여 데이터를 수집하면 저렴한 가격의 센서들을 통한 정보획득과 무선 네트워크를 통한 통신을 시행할뿐만 아니라 초전력 소모기술을 이용하여 대규모 교통데이터 정보수집을 시행하여 차량우선이 아닌 보행자 우선의 신호제어 알고리즘을 구현하는데 많은 잇점을 지니고 있다.