• Title/Summary/Keyword: Gain threshold

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Performance Improvement of Double Talk Detection before Convergence of the Echo Canceller by Using Linear Predictive Coding Filter Gain of the Primary Input Signal (주입력신호의 LPC 필터 이득을 이용한 반향제거기의 수렴전 동시통화검출 성능 개선)

  • Yoo, Jae-Ha
    • Journal of the Korean Institute of Intelligent Systems
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    • v.24 no.6
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    • pp.628-633
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    • 2014
  • This paper proposes a performance improvement method of the conventional double talk detection method which can operate before convergence of the echo canceller. The proposed method estimates the coefficients of the linear predictive coding(LPC) filter by using the primary input signal. The time-varying threshold for double talk detection is determined based on the LPC filter gain of the primary input signal level. The proposed method can reduce not only false detection rate which means wrong detection of single talk as double talk but also double talk detection delay. Computer simulation was performed using a long-term real speech signals. It is shown that the proposed method improves the conventional method in terms of lowering the false detection rate and shortening the detection delay.

The operating characteristics of strain-compensated 1.3$\mu$m GaInAsP/InP uncooled-LD with the structure of multiple quantum well and separate confinement heterostructure layers (응력완화 1.3$\mu$m GaInAsP/InP uncooled-LD의 다중양자우물층과 SCH층 구조에 따른 동작 특성)

  • 조호성;박경현;이정기;장동훈;김정수;박기성;박철순;김홍만;편광의
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.7
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    • pp.185-197
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    • 1996
  • We have adopted the strain compensated PBH(planar buried heterostructure) - LD in which the MQW active layer consisted of 1.4% compressively strained GainAsP (E$_{g}$ = 0.905eV) wells and 0.7% tensile strained GaInAsP(E$_{g}$ = 1.107eV) barriers grown by metal organic vapor phase epitaxy (MOVPE). We hav einvestigated effects of number of wells and the structure of the separate confinement heterostructure (SCH) layer in the strain-compensated MQW-PBH-LD. The threshold current, the external quantum efficiency, the transparency current density J$_{o}$, and the gain constant .beta. have been evaluated for uncoated MQW-PBH-LD. As the number of wells increases, the internal quantum efficiency and the transparency current density decreases, whereas the gain contant increases. The small width of the SCH layer shows the large internal quantum efficiency. The small internal loss and the large gain constant have been obtained by inserting the large bandgap SCH layer.

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Effect of Grating Structures and Mirror Positions on Characteristics of 1.55$\mu\textrm{m}$ DFB Lasers (1.55 $\mu\textrm{m}$ DFB 레이저의 특성에 미치는 Grating구조와 Mirror 위치의 영향)

  • Kwon, Kee-Young
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.31A no.9
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    • pp.128-138
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    • 1994
  • In 1.55.mu.m DFB lasers with two non-AR mirrors, I have analyzed the effect of the sturctures of indes and/or gain gratings and mirror positions on the threshold gains, the lasing frequencies, and the beam profiles in longitudinal direction of lasers. I have obtained the optimum condition of static characteristics that ${\Delta}{\Omega}$(the phase difference betweeen index grating and gain grating is 3${\pi}$/4, $({\kappa}L)_{i}$=4~6 in case of $({\kappa}L)_{i}$=0.9 and $({\kappa}L)_{i}$=3~5 in case of $({\kappa}L)_{i}$=0.7. The modal selectivity and intensity uniformity of this optimum condition are 2~2.5 times better than those of the gain-coupled DFB lasers ${\Delta}{\Omega}$=0). The gain-coupled DFB lasers${\Delta}{\Omega}$=0) have 10$^{10) times better modal selectivity and intensity uniformity than the loss-coupled DFB lasers(TEX>${\Delta}{\Omega}$=${\pi}$).

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Auto Gain/offset Based on Visibility of Spatial JND (공간 JND의 가시성 기반 자동 게인옵셋)

  • Kim, Mi-Hye;Jang, Ick-Hoon;Kim, Nam-Chul
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.46 no.4
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    • pp.16-22
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    • 2009
  • In this paper, we propose an auto gain/offset which considers the visibility of human visual system (HVS) and the histogram of a target image jointly. In the proposed method, the lower and upper clipping thresholds are determined to maximize the averaged visibility of the contrast-stretched image. The target image is then contrast-stitched by the gain and offset derived from the clipping thresholds. We define the visibility as a quantity related to the spatial JND, which means the threshold below which any change of a pixel from its textured neighbors is not recognized by the HVS. Experimental results show that the contrast-stretched images by the proposed method have better global and local contrasts compared to the results by some conventional methods.

A Study on The IC Design of 1[V] CMOS Operational Amplifier with Rail-to-rail Output Ranges (Rail-to-rail 출력을 갖는 1[V] CMOS Operational Amplifiler 설계 및 IC 화에 관한 연구)

  • Jeon, Dong-Hwan;Son, Sang-Hui
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.4
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    • pp.461-466
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    • 1999
  • A CMOS op amp with rail-to-rail input and output ranges is designed in a one-volt supply. The output stage of the op amp is used in a common source amplifier that operates in sub-threshold region to design a low voltage op amp with rail-to-tail output range. To drive heavy resistor and capacitor loads with rail-to-rail output ranges, a common source amplifier which has a low output resistance is utilized. A bulk-driven differential pair and a bulk-driven folded cascode amplifier are used in the designed op amp to increase input range and achieve 1 V operation. Post layout simulation results show that low frequency gain is about 58 ㏈ and gain bandwidth I MHz. The designed op amp has been fabricated in a 0.8${\mu}{\textrm}{m}$ standard CMOS process. The measured results show that this op amp provides rail-to-rail output range, 56㏈ dc gain with 1 MΩ load and has 0.4 MHz gain-bandwidth with 130 ㎊ and 1 kΩ loads.

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An Improvement of Speech Hearing Ability for sensorineural impaired listners (감음성(感音性) 난청인의 언어청력 향상에 관한 연구)

  • Lee, S.M.;Woo, H.C.;Kim, D.W.;Song, C.G.;Lee, Y.M.;Kim, W.K.
    • Proceedings of the KOSOMBE Conference
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    • v.1996 no.05
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    • pp.240-242
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    • 1996
  • In this paper, we proposed a method of a hearing aid suitable for the sensorineural hearing impaired. Generally as the sensorineural hearing impaired have narrow audible ranges between threshold and discomfortable level, the speech spectrum may easily go beyond their audible range. Therefore speech spectrum must be optimally amplified and compressed into the impaired's audible range. The level and frequency of input speech signal are varied continuously. So we have to make compensation input signal for frequency-gain loss of the impaired, specially in the frequency band which includes much information. The input sigaal is divided into short time block and spectrum within the block is calculated. The frequency-gain characteristic is determined using the calculated spectrum. The number of frequency band and the target gain which will be added input signal are estimated. The input signal within the block is processed by a single digital filter with the calculated frequency-gain characteristics. From the results of monosyllabic speech tests to evaluate the performance of the proposed algorithm, the scores of test were improved.

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Modeling the Relationship between Expected Gain and Expected Value

  • Won, Eugene J.S.
    • Asia Marketing Journal
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    • v.18 no.3
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    • pp.47-63
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    • 2016
  • Rational choice theory holds that the alternative with largest expected utility in the choice set should always be chosen. However, it is often observed that an alternative with the largest expected utility is not always chosen while the choice task itself being avoided. Such a choice phenomenon cannot be explained by the traditional expected utility maximization principle. The current study posits shows that such a phenomenon can be attributed to the gap between the expected perceived gain (or loss) and the expected perceived value. This study mathematically analyses the relationship between the expectation of an alternative's gains or losses over the reference point and its expected value, when the perceived gains or losses follow continuous probability distributions. The proposed expected value (EV) function can explain the effects of loss aversion and uncertainty on the evaluation of an alternative based on the prospect theory value function. The proposed function reveals why the expected gain of an alternative should exceed some positive threshold in order for the alternative to be chosen. The model also explains why none of the two equally or similarly attractive options is chosen when they are presented together, but either of them is chosen when presented alone. The EV function and EG-EV curve can extract and visualize the core tenets of the prospect theory more clearly than the value function itself.

Design of 850 nm Vertical-Cavity Surface-Emitting Lasers by Using a Transfer Matrix Method (전달 행렬 방법을 이용한 850 nm수직 공진기 레이저 구조의 최적설계)

  • Kim Tae-Yong;Kim Sang-Bae
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.41 no.1
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    • pp.35-46
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    • 2004
  • In comparison with edge-emitting lasers(EELs), predicting the output power and slope efficiency of Vertical-Cavity Surface-Emitting Lasers(VCSELs) is very difficult due to the absorption loss in DBR layers. However, by using transfer matrix method(TMM), we've made possible to calculate such parameters of multi-layer structures like VCSELs. In this paper, we've calculated the threshold gain, threshold current and slope efficiency through the methodology based on TMM. Also TMM is the way of customizing the VCSEL structure for the desired threshold current and slope efficiency by changing the number of DBR mirror layers.

Efficient Channel State Feedback Scheme for Opportunistic Scheduling in OFDMA Systems by Scheduling Probability Prediction

  • Ko, Soomin;Lee, Jungsu;Lee, Byeong Gi;Park, Daeyoung
    • Journal of Communications and Networks
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    • v.15 no.6
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    • pp.589-600
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    • 2013
  • In this paper, we propose a new feedback scheme called mode selection-based feedback by scheduling probability prediction (SPP-MF) for channel state feedback in OFDMA downlink system. We design the scheme such that it determines the more desirable feedback mode among selective feedback by scheduling probability prediction (SPP-SF) mode and bitmap feedback by scheduling probability prediction (SPP-BF) mode, by calculating and comparing the throughputs of the two modes. In both feedback modes, each user first calculates the scheduling probability of each subchannel (i.e., the probability that a user wins the scheduling competition for a subchannel) and then forms a feedback message based on the scheduling probability. Specifically, in the SPP-SF mode, each user reports the modulation and coding scheme (MCS) levels and indices of its best S subchannels in terms of the scheduling probability. In the SPP-BF mode, each user determines its scheduling probability threshold. Then, it forms a bitmap for the subchannels according to the scheduling probability threshold and sends the bitmap along with the threshold. Numerical results reveal that the proposed SPP-MF scheme achieves significant performance gain over the existing feedback schemes.

Electrical Characteristics of IGBT for Gate Bias under ${\gamma}$ Irradiation (게이트바이어스에서 감마방사선의 IGBT 전기적특성)

  • Lho, Young-Hwan;Lee, Sang-Yong;Kim, Jong-Dae
    • Proceedings of the KIEE Conference
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    • 2008.10b
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    • pp.165-168
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    • 2008
  • The experimental results of exposing IGBT (Insulated Gate Bipolar Transistor) samples to gamma radiation source show shifting of threshold voltages in the MOSFET and degradation of carrier mobility and current gains. At low total dose rate, the shift of threshold voltage is the major contribution of current increases, but for more than some total dose, the current is increased because of the current gain degradation occurred in the vertical PNP at the output of the IGBTs. In the paper, the collector current characteristics as a function of gate emitter voltage (VGE) curves are tested and analyzed with the model considering the radiation damage on the devices for gate bias and different dose. In addition, the model parameters between simulations and experiments are found and studied.

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