• Title/Summary/Keyword: Pulse sequences

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Jittered Pulse Repetition Interval Coder Based on M-sequence Codes for Counter-Countermeasure of a Radar (레이더의 반 대응 능력을 위한 M-시퀀스 코드 기반의 펄스반복간격 지터 코더 구현)

  • Pyo, Sun-Oh;Seo, Dong-Sun;Jo, Jun-Yong;Lee, Jae-Cheol
    • Journal of IKEEE
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    • v.15 no.2
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    • pp.171-178
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    • 2011
  • In this paper, a novel pulse repetition interval (PRI) jittering coder based on quasi-random M-sequence codes is proposed for improvement of counter-countermeasure capability in a radar. Each of the proposed jittered 256 PRI codes has a unique code chip combination with 256 code chips, such that any set of three consequent code chips (4 pulses) from any code appears only once among the entire code chip sequences of the codes. This indicates that only 4 of received pulses are enough to determine uniquely the exact timing position of the incoming pulse train (or code chip sequence) required for counter-countermeasure, as well as the identity of the transmitted code. To prove the proposed idea experimentally, the jittered PRI coder is implemented and demonstrated.

A New TE/TR Reduction Technique in MR Pulse Sequences and Its Application to Radial Imaging

  • 김용권;류연철;오창현
    • Proceedings of the KSMRM Conference
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    • 2003.10a
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    • pp.18-18
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    • 2003
  • 목적: MRI 시스템에서 얻어지는 Data는 TR(Repetition Time)과 TE(Echo Time)에 따라서 신호 대잡음비(SNR), 조직들간의 대조도(Contrast), Artifact 및 촬영시간이 결정된다. 이 연구에서는 TR/TE를 줄이는 기법을 이용한 Radial Imaging 영상기법을 제시하고자 한다. 대상 및 방법: 일반적인 Radial Imaging 기법에 HASTE 기법과 Non-uniform sampling 기법의 특징을 이용하여 구현하였으며, TR/TE를 줄일 수 있었으며 얻어진 K-space Data는 가변주파수 역 Fourier Transform을 이용하여 Projection Data를 재구성한 후 Back Projection 기법을 이용하여 최종 영상을 재구성한다.

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In Vitro imaging of MRI and Ultrasound for Colorectal Carcinoma (직결장암 조직의 자기공명영상과 초음파 소견에 대한 비교 연구)

  • Lee, Hwang Kyu;Jee, Keum Nahn;Hong, Sujin;Koh, Jae Hyang
    • Investigative Magnetic Resonance Imaging
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    • v.17 no.2
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    • pp.133-143
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    • 2013
  • Purpose : To evaluate and compare the accuracy of magnetic resonance imaging (MRI) and ultrasound (US) for detection and estimation of invasion depth of colorectal carcinoma (CRC) by correlation with histopathologic findings in vitro, and to find out the best MR pulse sequence for accurate delineation of tumor from surrounding normal tissue. Materials and Methods: Resected specimens of CRC from 45 patients were examined about tumor detectability and invasion depth of US using high frequency (5-17 MHz) linear transducer in a tube filled with normal saline and MRI in a 8-channel quadrate head coil. The institutional review board approved this study and informed consent was waived. MRI with seven pulse sequences of in- and out-of-phases gradient echo T1 weighted images, fast spin echo T2 weighted image and its fat suppression image, fast imaging employing steady-state acquisition (FIESTA) and its fat suppression image, and diffusion weighted image (DWI) were performed. In each case, both imaging findings of MRI and US were evaluated independently for detection and estimation of invasion depth of tumor by consensus of two radiologists and were compared about diagnostic accuracy according to the histopathologic findings as reference standard. Seven MR pulse sequences were evaluated on the point of accurate delineation of tumor from surrounding normal tissue in each specimen. Results: In specimens of CRC, both imaging modalities of MRI (91.1%) and US (86.7%) showed relatively high diagnostic accuracy to detect tumor and evaluate invasion depth of tumor. In early CRC, diagnostic accuracy of US was 87.5% and that of MRI was 75.0%. There was no statistically significant difference between two imaging modalities (p > 0.05). The best pulse sequence among seven MR sequences for accurate delineation of tumor from surrounding normal tissue in each specimen of CRC was fast spin echo T2 weighted image. Conclusion: MRI and US show relatively high diagnostic accuracy to detect tumor and evaluate invasion depth of resected specimen of CRC. The most excellent pulse sequence of MRI for accurate delineation of tumor from surrounding normal tissue in CRC is fast spin echo T2 weighted image.

Performance of PN Code Based Time Hopping Sequences in M-ary Ultra Wide Band Multiple Access Systems Using Equicorrelated Signal Sets (동일 상관 신호군을 이용하는 M-ary UWB 다원 접속 시스템에서 PN 부호 기반 시간 도약 시퀀스의 성능)

  • 양석철;신요안
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.10A
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    • pp.816-829
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    • 2003
  • In this paper, we evaluate the performance of PN (Pseudo Noise) code based time hopping sequences for M-ary UWB (Ultra Wide Band) multiple access systems using the equicorrelated signal sets. In particular, we consider two different types of M-ary UWB systems in UWB indoor wireless multipath channels: The first type of the systems (System #1) has identical symbol transmission rate regardless of the number of symbols M since the length of signal pulse train is fixed while M increases, and the second type of the systems (System #2) has the same bit transmission rate regardless of M since the length of signal pulse train is extended according to the increase of M. We compare the proposed systems with those using the ideal random time hopping sequence in terms of the symbol error rate performance. Simulation results show that the PN code based time hopping sequence achieves quite good performance which is favorably comparable to that of the ideal random sequence. Moreover, as M increases, we observe that System #2 shows better robustness against multiple access interference than System # 1.

Implementation of the wearable PTT measurement system for health monitoring during daily life (일상생활 건강 모니터링을 위한 착용형 PTT 측정 시스템의 구현)

  • Ye, Soo-Young;Noh, Yun-Hong;Jeong, Do-Un
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.15 no.1
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    • pp.220-226
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    • 2011
  • Device of the ECG and pulse signal was made to measure PTT signal using non-invasive method and possible to wearable. PTT alterations were observed according to position change using implemented system.It was needed to ECG and pulse to detect the PTT, used the photoplethymorgraphy appeared to change the blood volume. And also wireless sensor node which was able to Zigbee compatibility was used to transfer the detected ECG and pulse signal to PC. Noise was removed from transit data and algorithm was applied to calculate the PTT. After the evaluation of both the conventional measuring systems and the proposed photoplethymography measuring system, a highly effective and efficient formation and distribution sequences were found within the proposed photoplethymography measuring system.

Pulse Sequence based MR Images for Compressed Sensing Algorithm Applications (펄스열을 이용한 MR 영상의 Compressed Sensing 알고리즘 적용)

  • Gho, Sung-Mi;Choi, Na-Rae;Kim, Dong-Hyun
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.46 no.5
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    • pp.1-7
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    • 2009
  • In recent years, compressed sensing (CS) algorithm has been studied in various research areas including medical imaging. To use the CS algorithm, the signal that is to be reconstructed needs to have the property of sparsity But, most medical images generally don't have this property. One method to overcome this problem is by using sparsifying transform. However, MR imaging, compared to other medical imaging modality, has the unique property that by using appropriate image acquisition pulse sequences, the image contrast can be modified. In this paper, we propose the possibility of applying the CS algorithm with non-sparsifying transform to the pulse sequence modified MR images and improve the reconstruction performance of the CS algorithm by using an appropriate sparsifying transform. We verified the proposed contents by computer simulation using Shepp-Logan phantom and in vivo data.

Design and Implementation of an LED Mood Lighting System Using Personalized Color Sequence Generation

  • Jeong, Gu-Min;Yeo, Jong-Yun;Won, Dong Mook;Bae, Sung-Han;Park, Kyung-Joon
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.6 no.12
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    • pp.3182-3196
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    • 2012
  • In this paper, we present a new LED (Light Emitting Diode) mood lighting system interacting with smartphones based on the generation of different light sequences. In the proposed system, one light sequence is considered to be one unit of the service contents, which is then transmitted through a network and played in an LED lighting system. To this end, we propose a novel generation scheme using a smartphone, and a decoding/playing mechanism in an LED lighting system. The lighting sequences have a fixed period divided into predefined time units. Two modes - basic and interpolation - are supported in each time unit when playing a color sequence. In the basic mode, the color is maintained for the entire time unit, whereas in the interpolation mode the color is interpolated. The sequence is decoded and played in the lighting circuit by changing the duty cycle of a PWM (Pulse Width Modulation) signal. A demonstration system of the overall proposed method was using smartphones, a server and an LED lighting system. The results from this experiment show the validity and applicability of the proposed scheme.

Development of Flexible Ultrasound System for Elastography (탄성 영상법 개발을 위한 유연성 높은 초음파 시스템의 구현)

  • Kim, D.I.;Lee, S.Y.;Cho, M.H.
    • Journal of Biomedical Engineering Research
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    • v.33 no.1
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    • pp.32-38
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    • 2012
  • Recently, several ultrasound imaging techniques for tissue characterization have been developed. Among them, ultrasound elastography is regarded as the most promising modality and has been rapidly developed. One of ultrasound elastography techniques is shear modulus imaging. Normal and cancerous tissues show big difference of shear moduli and they have good image contrast. However shear wave elastography requires more complicated hardware and more computations for image reconstruction algorithm. Therefore new efficient techniques are being developed. In this paper, we have developed a very flexible ultrasound system for elastography experiments. The developed system has capabilities to acquire ultrasound RF data of all channels and generate arbitrary ultrasound pulse sequences. It has a huge amount of memories for RF data acquisition and a simple and flexible pulse generator. We have verified the performance of the system showing conventional B-mode images and preliminary results of elastography. The developed system will be used to verify our own reconstruction algorithm and to develop more efficient elastography techniques.

Echolocation Call Structure of Fourteen Bat Species in Korea

  • Fukui, Dai;Hill, David A.;Kim, Sun-Sook;Han, Sang-Hoon
    • Animal Systematics, Evolution and Diversity
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    • v.31 no.3
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    • pp.160-175
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    • 2015
  • The echolocation calls of bats can provide useful information about species that are generally difficult to observe in the field. In many cases characteristics of call structure can be used to identify species and also to obtain information about aspects of the bat's ecology. We describe and compare the echolocation call structure of 14 of the 21 bat species found in Korea, for most of which the ecology and behavior are poorly understood. In total, 1,129 pulses were analyzed from 93 echolocation call sequences of 14 species. Analyzed pulses could be classified into three types according to the pulse shape: FM/CF/FM type, FM type and FM/QCF type. Pulse structures of all species were consistent with previous studies, although geographic variation may be indicated in some species. Overall classification rate provided by the canonical discriminant analysis was relatively low. Especially in the genera Myotis and Murina, there are large overlaps in spectral and temporal parameters between species. On the other hand, classification rates for the FM/QCF type species were relatively high. The results show that acoustic monitoring could be a powerful tool for assessing bat activity and distribution in Korea, at least for FM/QCF and FM/CF/FM species.