• Journal of electromagnetic engineering and science
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• v.14 no.2
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• pp.79-81
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• 2014

In B-scan data measured by a pulse-type monostatic borehole radar, target signatures are seriously obscured by two clutters that differ in orientation and intensity. The primary clutter appears as a nearly constant time delay, which is caused by internal ringing between antenna and transceiver in the radar system. The secondary clutter occurs as an oblique time delay due to the guided borehole wave along the logging cable of the radar antenna. This issue led us to perform adaptive filtering processing for orientation-based clutter removal. This letter describes adaptive filtering processing consisting of a combination of edge detection, data rotation, and eigenimage filtering. We show that the hyperbolic signatures of a dormant air-filled tunnel target can be more distinctly enhanced by applying the proposed approach to the B-scan data, which are measured in a well-suited test site for underground tunnel detection.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.1
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• pp.124-130
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• 2014

In highly reliable and durable systems, failures due to aging might result in catastrophes. Aging monitoring techniques to prevent catastrophes by predicting such a failure are required. This paper presents a scan-based on-line aging monitoring scheme which monitors aging during normal operation and gives an alarm if aging is detected so that the system users take action before a failure occurs. We illustrate our modified scan chain architecture and aging monitoring control method. Experimental results show our simulation results to verify the functions of the proposed scheme.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.339-340
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• 2007

Gradient system에 spiral waveform 입력을 가하면 Hardware limitation에 의하여 만들어지는 gradient fields에 Transient time delay가 발생한다. 이를 보상하기 위하여, Gradient system을 R-L-C 회로로 모델링하여 재구성에 필요한 k-space trajectory를 보정하여 개선된 image를 획득하였다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.1 s.343
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• pp.37-44
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• 2006

This paper proposes an interconnect delay fault test (IDFT) solution on boards and SoCs based on IEEE 1149.1 and IEEE P1500. A new IDFT system clock rising edge generator which forces output boundary scan cells to update test data at the rising edge of system clock and input boundary scan cells to capture the test data at the next rising edge of the system clock is introduced. Using this proposed circuit, IDFT for interconnects synchronized to different system clocks in frequency can be achieved efficiently. Moreover, the proposed IDFT technique does not require any modification of the boundary scan cells or the standard TAP controller is simple in terms of test procedure and is small in terms of area overhead.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.4
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• pp.861-864
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• 2005

In this paper, we system the system design and numerical analysis of the ultrafast optical delay line using by optical phase modulator. The numerical analysis carried out with 1310nm, lops laser and electro-optic phase modulator. As the results of numerical analysis, we show a scanning rate of 0.5 GHz and a delay range of 19.0ps. Compare with mechanical delay line, the optical delay line has a high scanning speed and a high repetition rate.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.723-728
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• 1999

In this paper, we designed a Circular Path Built-In Self Test circuit and embedded it into a simple 8-bit microprocessor. Register cells of the microprocessor have been modified into Circular Path register cells and each register cells have been connected to form a scan chain. A BIST controller has been designed for controlling BIST operations and its operation has been verified through simulation. The BIST circuit described in this paper has increased size overhead of the microprocessor by 29.8% and delay time in the longest delay path from clock input to output by 2.9㎱.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.6
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• pp.631-639
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• 2016

Wi-Fi Direct standard technology has been widely deployed on the recently manufactured products such as smart phone, smart monitor, TV, set-top box, and gaming console, and it was published from Wi-Fi Alliance with the name of Wi-Fi Peer-to-Peer Technical Specifications (v1.4, 2014) for direct connection on the wireless communication environment. However, the connection process of this standard needs 5 to 10 seconds so it can lead to user's inconvenience as well as long delay for connection. From the focus of that this problem was derived from long discovery process composed of Scan and Find, as a result, the proposed scheme on this paper modified and adapted Scan and Find processes with reassembling steps of them for reducing the connection delay. In addition, the analysis and experiments were progressed for the evaluations of the proposed scheme.

• Journal of electromagnetic engineering and science
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• v.6 no.2
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• pp.110-116
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• 2006

A reflective array type surface acoustic wave(SAW) dispersive delay line(DDL) with high time-bandwidth at the V/UHF-band is designed and fabricated for compressive receiver applications. This type of the SAW DDL has the properties of the relative bandwidth of 20 %, the time delay of 49.89 usec, the insertion loss of 38.5 dB and the side lobe rejection of 39 dB. In comparison with a commercial SAW DDL, the insertion loss, amplitude ripple and side lobe rejection are improved by $1.5dB{\pm}0.6dB$ and 4 dB respectively. Using the fabricated SAW DDL, the prototype of the compressive receiver is developed. It is composed of RF converter, fast tunable LO, chirp LO, A/D converter, signal processing unit and control unit. This prototype system shows a fine frequency resolution of below 30 kHz with high scan rate.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.87-88
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• 2006

In this paper, we propose a new selective scanning scheme based on hand-off path information, which can provide an efficient reducing of delay time. This scheme eliminates almost of the scanning delay time by using Selective Scan based on Experience Path Table(SSEPT) algorithm and also completed hand-off within few milliseconds by using the next candidate channel indexing mechanism. Our scheme reduces the total number of scanning channels as well as the delay time on each channel. From the simulation result, we show that the proposed scheme is advantageous over the legacy schemes in terms of the scanning channels and the total delay time.

• Korean Journal of Optics and Photonics
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• v.16 no.6
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• pp.547-552
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• 2005

We have fabricated and characterized optical delay lines for optical coherence tomography, which is composed of cylindrical PZT(piezoelectric transducer) and single mode optical fiber. The polarization mode dispersion from the optical delay lines was compensated by the polarization controllers. By applying the duplex optical delay line, we minimized the thermal drift due to optical delay lines and obtained the scan range of 2 times that of a single optical delay line. The OCT system showed resolution of $18.6\pm0.5{\mu}m$, scanning range of 1.68mm, and scanning speed of 360.4mm/s.