• Journal of the Korean Data and Information Science Society
• /
• 제16권1호
• /
• pp.33-40
• /
• 2005

The estimating function method was proposed by Godambe(1985) for parameter estimation under unknown distributions for errors in the models. Threshold Autoregressive Heteroscedastic (Threshold-ARCH) models have been developed by Zakoian(1994) and Li and Li(1996) for explaining the asymmetric properties in the financial time series data. In this paper, we apply the estimating function method to the Threshold-ARCH model and show that the proposed estimators perform better than the MLE under the heavy-tailed distributions.

• Nuclear Engineering and Technology
• /
• 제52권8호
• /
• pp.1771-1776
• /
• 2020

Adverse effects in the measured gamma spectrum caused by radioactive statistical fluctuations, gamma ray scattering, and electronic noise can be reduced by energy spectrum denoising. Wavelet threshold denoising can be used to perform multi-scale and multi-resolution analysis on noisy signals with small root mean square errors and high signal-to-noise ratios. However, in traditional wavelet threshold denoising methods, there are signal oscillations in hard threshold denoising and constant deviations in soft threshold denoising. An improved wavelet threshold calculation method and threshold processing function are proposed in this paper. The improved threshold calculation method takes into account the influence of the number of wavelet decomposition layers and reduces the deviation caused by the inaccuracy of the threshold. The improved threshold processing function can be continuously guided, which solves the discontinuity of the traditional hard threshold function, avoids the constant deviation caused by the traditional soft threshold method. The examples show that the proposed method can accurately denoise and preserves the characteristic signals well in the gamma energy spectrum.

• 전기의세계
• /
• 제23권4호
• /
• pp.53-59
• /
• 1974

This paper investigates the theoretical properties of a logic element called the multithreshold threshold element, which is a generalization of the single-threshold threshold element. The primary partition os a systematic method of obtaining the multi-threshold realization of a switching function by the index numbers. The concept of comparable vertices of the same index numbers introduced in this paper is very promising for testing the multi-threshold partition by the initial condition to be defined by the minterms of the same index numbers.

• 한국전기전자재료학회논문지
• /
• 제32권2호
• /
• pp.104-109
• /
• 2019

An analytical threshold voltage model is proposed to analyze the threshold voltage roll-off and drain-induced barrier lowering (DIBL) for a junction-based double-gate (JBDG) MOSFET and a junction-less double-gate (JLDG) MOSFET. We used the series-type potential distribution function derived from the Poisson equation, and observed that it is sufficient to use n=1 due to the drastic decrease in eigenvalues when increasing the n of the series-type potential function. The threshold voltage derived from this threshold voltage model was in good agreement with the result of TCAD simulation. The threshold voltage roll-off of the JBDG MOSFET was about 57% better than that of the JLDG MOSFET for a channel length of 25 nm, channel thickness of 10 nm, and oxide thickness of 2 nm. The DIBL of the JBDG MOSFET was about 12% better than that of the JLDG MOSFET, at a gate metal work-function of 5 eV. It was also found that decreasing the work-function of the gate metal significantly reduces the DIBL.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제53권10호
• /
• pp.510-514
• /
• 2004

In this paper, we analytically examine the voltage transfer function dependent on input conditions for an N-Input NAND Gate. The logic threshold voltage, defined as a voltage at which the input and the output voltage become equal, changes as the input condition changes for a static NAND Gate. The logic threshold voltage has the highest value when all the N-inputs undergo transitions and it has the lowest value when only the last input connected to the last NMOS to ground, makes a transition. This logic threshold voltage difference increases as the number of inputs increases. Therefore, in order to provide a near symmetric voltage transfer function, a multistage N-Input Gate consisting of 2-Input Logic Gates is desirable over a conventional N-Input Gate.

• 대한치과보철학회지
• /
• 제29권1호
• /
• pp.215-232
• /
• 1991

In this study, oral sensory function in the osseointegrated root form implant-supported prostheses wearers was estimated by measuring occlusal tactile perception threshold of thickness and sensibility threshold against lateral static loading, and comparing with normal dentition subjects and complete denture wearers group. Osseointegrated root form implants seemed to be restored in the sensation to some extent, and so, dental implants restored edentulous patients in a wide meaning. Conclusions were summarized as following. 1. Occlusal tactile perception threshold of thickness was highest in complete denture wearers group, following by implant-supported prostheses wearers group, normal dentition subjects group. 2. In the implant-supported prostheses wearers group, occlusal tactile perception threshold of opposing artificial teeth case was higher than of opposing natural or opposing implantsupported teeth case. 3. Sensibility threshold against lateral loading of complete denture wearers and implantsupported prostheses wearers group was higher than that of normal dentition subject group. 4. In the implant-supported prostheses group, sensibility threshold against lateral loading was not significantly different between upper and lower jaws. 5. In occlusal tactile perception threshold of thickness and sensibility threshold against lateral loading test, there was no regularity among values of each tooth, and no significant difference between anterior and posterior teeth as well.

• 한국정밀공학회지
• /
• 제16권5호통권98호
• /
• pp.48-57
• /
• 1999

Applications of thresholding technique are based on the assumption that object and background pixels in a digital image can be distinguished by their gray level values. For the segmentation of more complex images, it is necessary to resort to multiple threshold selection techniques. This paper describes a new method for multiple threshold selection of gray level images which are not clearly distinguishable from the background. The proposed method consists of three main stages. In the first stage, a probability distribution function for a gray level histogram of an image is derived. Cluster points are defined according to the probability distribution function. In the second stage, fuzzy partition matrix of the probability distribution function is generated through the fuzzy clustering process. Finally, elements of the fuzzy partition matrix are classified as clusters according to gray level values by using max-membership method. Boundary values of classified clusters are selected as multiple threshold. In order to verify the performance of the developed algorithm, automatic inspection process of ball grid array is presented.

• 한국통신학회논문지
• /
• 제29권12C호
• /
• pp.1660-1668
• /
• 2004

본 논문에서는 간단한 구조, 적은 계산량과 안정된 빠른 수렴속도를 가진 RBF (Radial Basis Function) 신경회로망을 이용한 이중 임계값 방식의 음성구간 검출기 알고리즘을 제안하고 시뮬레이션을 통해 유용성을 확인하였다. 음성압축기에 사용되는 CELP (Code-Excited Linear Prediction) 파라미터들을 신경회로망 입력으로 하여 잡음에 강하게 반응하게 하였고, 음성구간 검출기의 성능향상을 위해 음성구간과 침묵구간에서 다른 임계값을 사용하는 이중 임계값 방식을 적용하였다. 실험 결과 이중 임계값을 이용한 RBF 신경망 음성구간 검출기는 G.729 Annex B 음성구간 검출기 보다 우수한 성능을 보였고, 기존의 MLP (Multi Layer Perceptron) 신경회로망을 이용한 음성구간 검출기와 비교하여 음성구간에서는 비슷한 성능을 보였으나 침묵구간에서 25% 정도의 성능향상을 보였다.

• Journal of information and communication convergence engineering
• /
• 제9권6호
• /
• pp.733-737
• /
• 2011

This paper has studied subthreshold characteristics for double gate(DG) MOSFET using Gaussian function in solving Poisson's equation. Typical two dimensional analytical transport models have been presented for symmetrical Double Gate MOSFETs (DGMOSFETs). Subthreshold swing and threshold voltage are very important factors for digital devices because of determination of ON and OFF. In general, subthreshold swings have to be under 100mV/dec, and threshold voltage roll-off small in short channel devices. These models are used to obtain the change of subthreshold swings and threshold voltage for DGMOSFET according to channel doping profiles. Also subthreshold swings and threshold voltages have been analyzed for device parameters such as channel length, channel thickness and channel doping profiles.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2003년도 컴퓨터소사이어티 추계학술대회논문집
• /
• pp.87-90
• /
• 2003

본 논문에서는 정현파를 이용한 spread-spectrum watermarking 에서 비가청성을 높이기 위한 방법과 효율적인 threshold 설정 방법을 제안한다. 제안하는 방법에서는 spread-spectrum 기법을 사용할 때 계산량이 많이 요구되는 심리음향모델 계산을 피하면서도 가청잡음을 줄이기 위한 방법을 제시한다. 또한 outlier 를 이용하여 워터마크 검출에서 적절한 threshold 설정방법을 제안한다.