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  • Title/Summary/Keyword: 펄스열

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The Optical Cell Compressor and Decompressor using SOA Gates and Optical Feedback Loops (SOA 게이트와 광 궤환 루프를 이용한 광 셀 압축기 및 역압축기)

  • 김광수
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.10B
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    • pp.1722-1731
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    • 2000
  • In this paper we proposed a new type of the Optical Cell Compressor and Decompressor which are essential modules in TDM of TDM/WDM Hybrid OPtical ATM Switch structure. This proposed structure frastically lessens hardwares for realization by using SOA gates and optical feedback loops in the process of compression and decompression. Also it is able to compress and decompress the large capacity optical pulse stream just with a few of stages cascade connected. We proved it's possibility for systematic application through 4-bit compression experiment.

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The Effects of Temperature on Mechanical Properties in Pulse-Electrodeposited Cu Thin Film (온도에 따른 펄스 전해도금 구리박막의 물성변화)

  • Park, Sang-U;Seo, Seong-Ho;Jin, Sang-Hyeon;Wang, Geon;Yu, Bong-Yeong
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2015.05a
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    • pp.55-55
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    • 2015
  • 오늘날 전해동박은 리튬이온전지의 집전체, PCB, FPCB등의 핵심부품으로써, 산업 전반에 걸쳐 널리 사용되고 있다. 그러나 전자 회로의 미세화로 인한 열 발생, 낮은 강도에 의한 신뢰성 하락 등이 문제가 되고 있는 실정이다. 구리에 나노 쌍정을 높은 밀도로 형성하게 되면, 전기 저항의 변화 없이 기계적 강도를 높이는데 도움이 된다. 특히 펄스 전해증착에서는 높은 전류밀도가 인가되기 때문에 고밀도의 나노쌍정을 얻을 수 있다는 점이 여러 논문에서 보고되었다. 이번 연구에서는 펄스도금 조건에서 온도 조건의 변화를 통해 강도가 향상됨을 알 수 있었다.

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Nonthermal Sterilization of Pathogenic Escherichia coli by Intense Pulsed Light Using a Batch System (회분식 광펄스 처리에 의한 병원성 대장균의 비가열 살균)

  • Kim, Ae-Jin;Shin, Jung-Kue
    • Korean Journal of Food Science and Technology
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    • v.47 no.1
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    • pp.81-86
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    • 2015
  • Intense pulsed light (IPL), a nonthermal technology, has attracted increasing interest as a food processing technology. However, its efficacy in inactivating microorganisms has not been evaluated thoroughly. In this study, we investigated the influence of IPL treatment on the inactivation of Escherichia coli O157:H7 depending on light intensity, treatment time, and pulse number. Increased light intensity from 500 V to 1,000 V, raised the inactivation rate at room temperature. At 1000 V, the cell numbers were reduced by 7.1 log cycles within 120 s. In addition, increased pulse number or decreased distance between the light source and sample surface also led to an increase in the inactivation rate. IPL exposure caused a significant increase in the absorption at 260 nm of the suspending agent used in our experiments. This indicates that IPL-treated cells were damaged, consequently releasing intracellular materials. The growth of IPL-irradiated cells were delayed by about 5 h. The degree of damage to the cells after IPL treatment was confimed by transmission electron microscopy.

Measurements of Acoustic Properties of Materials by Spectral Analysis of Ultrasonic Pulses (초음파 펄스의 주파수해석에 의한 재료의 음향특성 측정)

  • Ha, Kang-Lyeol;Kim, Moo-Joon;Lee, Jong-Kyu;Kim, Sung-Boo;Noriyoshi, Chubachi
    • The Journal of the Acoustical Society of Korea
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    • v.14 no.6
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    • pp.40-47
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    • 1995
  • A system for measurement of ultrasonic velocity, attenuation and complex modulus of materials by using the spectral analysis method of pulses has been constructed and its performances are estimated. The system has a mechanical scanning part of an acoustic microscope with a ZnO plane wave transducer of the resonant frequency of 85MHz. Ultrasonic velocity has been obtained by the intervals of maxima (or minima) on the power spectrum of a pulse train reflected from the surface and bottom of a specimen, and attenuation has been obtained by the power spectra of three pulses reflected from the surface and the bottom of a specimen and the surface of a standard specimen. The measured results for materials such as fused quartz, polyester show that the system has very high accuracy.

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A Study on the Design of Varistor Prevented from Thermal Runaway to Improve Safety (안정성 개선을 위해 열폭주 방지 기능을 내장한 배리스터 설계에 관한 연구)

  • Jung, Tae-Hun;Shin, Hee-Sang;Cho, Sung-Min;Lee, Hee-Tae;Lee, Jun-Kyu;Kim, Jae-Chul
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.2
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    • pp.69-76
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    • 2010
  • Recently, the natural environment changes drastically and the frequency of occurrence for lightning has gradually been increased. Such lightning delivers high volume of energy along the power line and communication line to the equipment in use. The high volume of energy arising from the lightning surge develops in fast velocity to destroy the facilities in power source and many other facilities in operation in sequential destruction with vast energy. This paper examines the characteristics of ZnO varistor to prevent from thermal runaway. We carry out performance evaluation of electrical characteristics on ZnO varistor. we will develop ZnO varistor Prevented from thermal explosion using test result of this paper.

Performance Analysis of an Optical CDMA System for multi-user Environment (다중 사용자 환경에서의 광 CDMA 시스템 성능 분석)

  • 전상영;김영일;이주희
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.6B
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    • pp.1134-1141
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    • 1999
  • In this paper, we implement an optical code division multiple access(OCDMA) system and analyze the performance of the implemented system. In the implemented system, a transmitter encodes input data into optical pulses by using laser diode, and spreads the encoded pulses in an encoder which consists of 4 stage delay lines. The decoder which is the same structure as that of encoder delays and combines the spreaded pulses, and thus recovers the original data. At first, we discuss the auto- and cross-correlations of OCDMA signals under both environments of single user and multi-users, and then verify the simulation results with experimental results. We also evaluate the effect of a number of stages of delay line and code length on the system performance through computer simulations. As experimental results we can see that if the decoder have the same configuration as that of encoder, the peak auto-correlation characteristics can be achieved, and thus we can recover the original data from received data. As simulation results we can see that although bit error rate decreases as code length decreases or the number of stage of delay line increases, it is difficult to implement the system because the pulse width becomes narrow. From the results, we can apply CDMA technologies to optical communication networks.

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Development of the Line Scan Diffusion Weighted Imaging at Low Tesla Magnetic Resonance Imaging System (저자장 자기공명영상시스템에서 선주사확산강조영상기법 개발)

  • Hong, Cheol-Pyo;Lee, Dong-Hoon;Lee, Do-Wan;Lee, Man-Woo;Paek, Mun-Young;Han, Bong-Soo
    • Journal of the Korean Society of Radiology
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    • v.2 no.2
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    • pp.31-38
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    • 2008
  • Line scan diffusion weighted imaging (LSDI) pulse sequence for 0.32 T magnetic resonance imaging (MRI) system was developed. In the LSDI pulse sequence, the imaging volume is formed by the intersection of the two perpendicular planes selected by the two slice-selective π/2-pulse and π-pulse and two diffusion sensitizing gradients placed on the both side of the refocusing π-pulse and the standard frequency encoding readout was followed. Since the maximum gradient amplitude for the MR system was 15 mT/m the maximum b value was 301.50s/mm2. Using the developed LSDI pulse sequence, the diffusion weighted images for the aqueous NaCl solution phantom and triacylglycerol solution phantom calculated from the line scan diffusion weighted images gives the same results within the standard error range (mean diffusivities = 963.90±79.83(×106mm2/s) at 0.32 T, 956.77±4.12(×106mm2/s) at 1.5 T) and the LSDI images were insensitive to the magnetic susceptibility difference and chemical shift.

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Physiological Changes of Saccharomyces cerevisiae by High Voltage Pulsed Electric Field Treatments (고전압 펄스 전기장 처리에 의한 Saccharomyces cerevisiae의 생리적 변화)

  • Park, Hee Ran;Yoon, So Jung;Park, Han-Sul;Shin, Jung-Kue
    • Korean Journal of Food Science and Technology
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    • v.45 no.5
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    • pp.590-597
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    • 2013
  • High voltage pulsed electric fields (PEF) treatment is a promising non-thermal processing technology that can replace or partially substitute for thermal processes. The aim of this research was to investigate the microbial inactivation mechanisms by PEF treatment in terms of physiological changes to Saccharomyces cerevisiae. PEF was applied at the electric field strength of 50 kV/cm, treatment time of 56 μs and temperature of 40C. The microbial cells treated with PEF showed loss of salt tolerance on the cell membrane and collapse of the relative pH gradient on in-out of cells. Cell death or injury resulted from the breakdown of homeostasis, decreased H+-ATPase activity, and loss of glycolysis activity.

Intra- and Extra-cellular Mechanisms of Saccharomyces cerevisiae Inactivation by High Voltage Pulsed Electric Fields Treatment (고전압 펄스 전기장에 의한 Saccharomyces cerevisiae의 세포내·외적 사멸 기작 연구)

  • Lee, Sang-Jae;Shin, Jung-Kue
    • Korean Journal of Food Science and Technology
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    • v.47 no.1
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    • pp.87-94
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    • 2015
  • High voltage pulsed electric fields (PEF) treatment is one of the more promising nonthermal technologies to fully or partially replace thermal processing. The objective of this research was to investigate the microbial inactivation mechanisms of PEF treatment in terms of intra- and extracellular changes in the cells. Saccharomyces cerevisae cells treated with PEF showed cellular membrane damage. This resulted in the leakage of UV-absorbing materials and intracelluar ions, which increased with increasing treatment time and electric fields strength. This indicates that PEF treatment causes cell death via membrane damage and physical rupture of cell walls. We further confirmed this by Phloxine B staining, a dye that accumulates in dead cells. Using scanning and transmission electron microscopy, we observed morphological changes as well as disrupted cytoplasmic membranes in PEF treated S. cerevisae cells. In addition, PEF treatment led to damaged chromosomal DNA in S. cerevisiae.

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.