• Title/Summary/Keyword: dB difference

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Analysis of Multi-Media DS/CDMA System (다매체 직접수열 대역확산 다중접속 시스템에 관한 연구)

  • 김홍직;김상우
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.6A
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    • pp.775-781
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    • 1999
  • A multi-media variable processing gain DS/CDMA system are considered. Two types of information sources with different rates and transmitting powers are assumed to be stransmitted simultaneously in the same channel. Average signal-to-noise ratios at the correlation receiver outputs for each type of information sources are analytically derived as funtions of partial cross-correlations between spreading code sequences. As the difference of information rates between information sources increase, the difference between signal-to-noise ratio regarding random spreading code and that regarding pseudo random spreading code increases (maximum 1.3dB). The result can provide a analytical tools for use in multi-media DS/CDMA system design.

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Mapping Paddy Rice Varieties Using Multi-temporal RADARSAT SAR Images

  • Jang, Min-Won;Kim, Yi-Hyun;Park, No-Wook;Hong, Suk-Young
    • Korean Journal of Remote Sensing
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    • v.28 no.6
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    • pp.653-660
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    • 2012
  • This study classified paddy fields according to rice varieties and monitored temporal changes in rice growth using SAR backscatter coefficients (${\sigma}^{\circ}$). A growing period time-series of backscatter coefficients was set up for nine fine-beam mode RADARSAT-1 SAR images from April to October 2005. The images were compared with field-measured rice growth parameters such as leaf area index (LAI), plant height, fresh and dry biomass, and water content in grain and plants for 45 parcels in Dangjin-gun, Chungnam Province, South Korea. The average backscatter coefficients for early-maturing rice varieties (13 parcels) ranged from -18.17 dB to -6.06 dB and were lower than those for medium-late maturing rice varieties during most of the growing season. Both crops showed the highest backscatter coefficient values at the heading stage (late July) for early-maturing rice, and the difference was greatest before harvest for early-maturing rice. The temporal difference in backscatter coefficients between rice varieties may play a key role in identifying early-maturing rice fields. On the other hand, comparisons with field-measured parameters of rice growth showed that backscatter coefficients decreased or remained on a plateau after the heading stage, even though the growth of the rice canopy had advanced.

A Design and Fabrication of Bandpass Filter using Miniaturized Square SIR (소형화된 구형 SIR을 이용한 대역통과필터 설계 및 제작)

  • Nam, Hun;Lim, Yeong-Seog
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.38 no.2
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    • pp.13-18
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    • 2001
  • In this paper, a four-pole quasi-elliptic function bandpass filter of 1.95GHz center frequency with 60 MHz bandwidth for IMT-2000 using miniaturized square SIR(Stepped Impedance Resonator) is designed and fabricated. The simulation of NUFDTD(Nonuniform Finite Difference Time Domain) is used to design the resonator and to calculate the coupling coefficient of three basic structures. The size reduction of miniaturized square SIR resonator is about more than 50% compare with a square open loop resonator. Bandpass filter using this resonator shows good microwave characteristic with the harmonic suppression of about 19dB. The results of measurements are almost similar to those of simulation.

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An Improvement of the Field Uniformity inside the Reverberation Chamber with Inclined QRD Set (경사진 QRD를 이용한 전자파 잔향실 내 전자기장 균일도 향상을 위한 연구)

  • Lee, Byoung-Jun;Kim, Hye-Kwang;Rhee, Joong-Geun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.18 no.6 s.121
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    • pp.577-583
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    • 2007
  • The field uniformity inside the reverberation chamber has been improved using sets of quadratic residue diffuser (QRD). The electromagnetic field inside the reverberation chamber with the dimension of $100{\times}80{\times}80cm$ has been analyzed by the finite-difference time-domain(FDTD) method. The calculated fields in a $40{\times}30{\times}30cm$ test volume have been sampled to obtain a standard deviation and field uniformity. Results show that the standard deviation of the calculated field and uniformity have been improved by varying angles and orientation of the inclined surfaces of the QRDs installed inside the reverberation chamber.

Is Ossiculoplasty Necessary in Canal Wall Down Mastoidectomy? Comparison of Clinical Outcomes Between Type 0 Tympanoplasty and Ossiculoplasty

  • Suh, Michelle J.;Park, Jin-A;Yi, Hee Jun;Song, Chan Il
    • Journal of Audiology & Otology
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    • v.25 no.2
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    • pp.104-109
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    • 2021
  • Background and Objectives: To assess whether the audiological and clinical outcomes of type 0 tympanoplasty (T0) performed using cartilage were comparable with those of ossiculoplasty in patients who underwent canal wall down mastoidectomy (CWDM). Subjects and Methods: This study included patients who had chronic otitis media with cholesteatoma and underwent CWDM with ossiculoplasty involving partial ossicular replacement prosthesis (PORP), total ossicular replacement prosthesis (TORP), or T0. Anatomical success rates and hearing outcomes were analyzed. Results: Seventy-two patients were included in this study; 29 of them underwent CWDM with T0, 27 underwent CWDM with PORP, while 16 underwent CWDM with TORP. The difference in mean improvement in the air-bone gap (ABG) between the groups was not significant. The differences in the rates of ABG closure to ≤10 dB HL (p=0.030) and ≤20 dB HL (p=0.029) were significant. There were significant differences in improvements in the ABG at 3 kHz among the PORP, TORP, and T0 groups. Conclusions: The audiological outcomes of CWDM with ossiculoplasty seemed to be better than those of CWDM with T0 with no significant difference in the incidence of complications following ossiculoplasty and T0.

Is Ossiculoplasty Necessary in Canal Wall Down Mastoidectomy? Comparison of Clinical Outcomes Between Type 0 Tympanoplasty and Ossiculoplasty

  • Suh, Michelle J.;Park, Jin-A;Yi, Hee Jun;Song, Chan Il
    • Korean Journal of Audiology
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    • v.25 no.2
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    • pp.104-109
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    • 2021
  • Background and Objectives: To assess whether the audiological and clinical outcomes of type 0 tympanoplasty (T0) performed using cartilage were comparable with those of ossiculoplasty in patients who underwent canal wall down mastoidectomy (CWDM). Subjects and Methods: This study included patients who had chronic otitis media with cholesteatoma and underwent CWDM with ossiculoplasty involving partial ossicular replacement prosthesis (PORP), total ossicular replacement prosthesis (TORP), or T0. Anatomical success rates and hearing outcomes were analyzed. Results: Seventy-two patients were included in this study; 29 of them underwent CWDM with T0, 27 underwent CWDM with PORP, while 16 underwent CWDM with TORP. The difference in mean improvement in the air-bone gap (ABG) between the groups was not significant. The differences in the rates of ABG closure to ≤10 dB HL (p=0.030) and ≤20 dB HL (p=0.029) were significant. There were significant differences in improvements in the ABG at 3 kHz among the PORP, TORP, and T0 groups. Conclusions: The audiological outcomes of CWDM with ossiculoplasty seemed to be better than those of CWDM with T0 with no significant difference in the incidence of complications following ossiculoplasty and T0.

Nodakenin and Decursin Contents of Fermented Angelicae Gigantis Radix by 4 Species Strain (4종의 발효균주가 당귀의 nodakenin과 decursin의 함량에 미치는 변화)

  • Park, Jin-Han;Jung, Ji-Wook;Kweon, Kee-Tae;Seo, Min-Jun;Seo, Eun-Kyoung;Park, Yong-Ki;Lee, Je-Hyun
    • The Korea Journal of Herbology
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    • v.25 no.4
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    • pp.7-10
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    • 2010
  • Objectives : The purpose of this study was to investigate the nodakenin and decursin contents in each fermented Angelicae gigantis Radix by 4 species of ferment strains. Methods : The strains of fermented Angelicae gigantis Radix were Lactobacillus plantarum(SE1), L. acidophilus(AC), Bacillus subtilis(B2) and B. licheniformis(BL2). The fermentative changes of nodakenin and decursin were analyzed using HPLC. Results : All of 4 species strains reduced nodakenin and decursin concentration in Angelicae gigantis Radix by fermentation. But fermentability were difference between strains. The nodakenin concentration of AC was lower than B2. The decursin concentrations of SE1 and AC were lower than B2 and BL2. Conclusions : 4 species of fermental strain were difference decomposable rate with nodakenin and decursin in fermented Angelicae gigantis Radix.

Stereo-video Synchronization for 3D Video Transmission (3차원 비디오 전송을 위한 스테레오비디오 동기화 방법)

  • Lee, Dong-Jin;Lee, Seon-Oh;Sim, Dong-Gyu;Lee, Hyuk-Joon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.4B
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    • pp.349-359
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    • 2009
  • In this paper, we propose a stereo-video transmission method for reduction of delay and maximization of 3D effect. Conventional multimedia synchronization algorithms were designed to achieve minimum delay and synchronize multiple video and audio streams, however, they could not be effective for 3D video transmission. In this paper, we proposed a synchronization algorithm by considering the minimum error of time difference between streams for 3D effect. The minimum error of time difference for 3D effect was derived based on a 3D subjective quality test. We compute display time of the delivered videos within the allowed time-difference and the video are displayed according to the display time. To evaluate the performance of the proposed algorithm, we implemented a real-time video communication system and subjective quality test has been conducted with the proposed system. We found that video quality displayed by the proposed system. We found that video quality displayed by the proposed algorithm ranks 'good' and 'excellent' in the DMOS (Differential Mean Opinion Score) scale, based on the MOS (Mean Opinion Score) test.

Routine double-J stenting for live related donor kidney transplant recipients: It doesn't serve the purpose, but does it serve a better purpose?

  • Kumar, Vikash;Punatar, Chirag B;Jadhav, Kunal K;Kothari, Jatin;Joshi, Vinod S;Sagade, Sharad N;Kamat, Madhav H
    • Investigative and Clinical Urology
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    • v.59 no.6
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    • pp.410-415
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    • 2018
  • Purpose: Despite meticulous techniques, surgical complications continue to be problematic in kidney transplant recipients. Role of routine stenting to reduce complications is controversial. In this study, we compare incidence of early urological complications, lymphoceles, urinary tract infections (UTI) and graft function; with or without double-J stenting. Materials and Methods: All patients who underwent live related donor renal transplantation from February 2014 to February 2016 were included. Transplants prior to February 2015 were without routine stenting; subsequent transplants were with routine stenting. Patients with neurogenic bladder, previously operated bladder and delayed or low urinary output were excluded. Followup was for at least three months. Descriptive statistics was performed for all parameters. Chi square test and Fisher's Exact test were used for qualitative variables. For quantitative variables, Mann-Whitney test was used to test median difference and independent samples t-test for mean difference. The p-value ${\leq}0.05$ was considered significant. Results: We analysed 74 patients (34 stented and 40 non-stented). There was no difference in the incidence of urinary leak, anastomotic obstruction, lymphoceles or UTI (p>0.4 for all comparisons). However, mean estimated glomerular filtration rate at sixth day, 14th day, one month and two months were 76.1 vs. 61.5 (p=0.025), 72.1 vs. 56.6 (p=0.005), 79.4 vs. 63.1 (p=0.002) and 82.0 vs. 63.3 (p=0.001) in the stented versus non-stented groups. Conclusions: Placement of ureteral stent in renal transplant does not significantly affect the incidence of early urinary complications or UTI. However, graft function is significantly better in stented recipients, at least in the short term.

A study on the effect of leading sound and following sound on sound localization (선행음 및 후속음이 음원의 방향지각에 미치는 영향에 관한 연구)

  • Lee, Chai-Bong
    • Journal of the Institute of Convergence Signal Processing
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    • v.16 no.2
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    • pp.40-43
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    • 2015
  • In this paper, the effects of the leading and the following sounds with single frequency on sound localization are investigated. The sounds with different levels and ISIs(Inter Stimuli Intervals) were used. The width of test sound is 2ms, and those of the leading and the following sounds are 10ms. 1 kHz of the test sound is utilized. The arrival time difference in the subject's ears is set to be 0.5ms. The four kinds of level differences used for one ISI are 0, -10, -15, and -20dB interval. The leading sound is found to have more effect on sound localization than the following sound is. The effect of the leading sound is also found to be dependent on the value of ISI. When the value of the ISI is small, different effects affecting the sound localization are observed.