• 응용통계연구
• /
• 제35권2호
• /
• pp.311-325
• /
• 2022

0의 값을 과도하게 포함하는 가산자료는 다양한 연구 분야에서 흔히 나타난다. 영과잉 모형은 영과잉 가산자료를 분석하기 위해 가장 일반적으로 사용되는 모형이다. 영과잉 모형에 대한 전통적인 베이지안 추론은 조건부 사후분포의 형태가 폐쇄형 분포로 나타나지 않아 모형 적합 과정이 용이하지 않다는 한계점이 존재했다. 그러나 최근 Pillow와 Scott (2012)과 Polson 등 (2013)이 제안한 폴랴-감마 자료확대전략으로 인해, 로지스틱 회귀모형과 음이항 회귀모형에서 깁스 샘플링을 통한 추론이 가능해지면서, 영과잉 모형에 대한 베이지안 추론이 용이해졌다. 본 논문에서는 베이지안 추론에 기반한 영과잉 음이항 회귀모형을 Min과 Agresti(2005)에서 분석된 약학 연구 자료에 적용해본다. 분석에 사용된 자료는 경시적 영과잉 가산자료로 복잡한 자료 구조를 가지고 있다. 모형 적합 과정에서는 깁스 샘플링을 통한 추론을 수행하기 위해 폴랴-감마 자료확대전략을 사용한다.

• 한국해양공학회지
• /
• 제30권1호
• /
• pp.18-24
• /
• 2016

Stabilizer fins are installed on each side of a ship to control its roll motion. The most common stabilizer fin is a rolling control system that uses the lift force on the fin surface. If the angle of attack of a stabilizer fin is zero or the speed is zero, it cannot control the roll motion. The Coanda effect is well known to generate lift force in marine field. The performance of stabilizer fin that applies the Coanda effect has been verified by model tests and numerical simulations. It was found that a stabilizer fin that applied the Coanda effect at Cj = 0.085 and a zero angle of attack exactly coincided with that of the original fin at α = 26°. In addition, the power needed to generate the Coanda effect was not high compared to the motor power of the original stabilizer fin.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2004년도 전력전자학술대회 논문집(2)
• /
• pp.630-634
• /
• 2004

A new three phase three-level Pulse Width Modulation (PWM) Switched Voltage Source (SVS) inverter with zero neutral point potential is proposed. The major advantage is that the peak value of the phase output voltage is twice as high as that of the conventional neutral-point-clamped (NPC) PWM inverter. Furthermore, three-level waveforms of the proposed inverter can be achieved without switch voltage unbalance problem. Since the average neutral point potential of the proposed inverter is zero, the common ground between input stage and output stage is possible. The proposed inverter is verified by experimental results based on a laboratory prototype.

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제15권3호
• /
• pp.170-175
• /
• 2015

Reliability demonstration tests (RDT's) are widely employed in design verification and process validation stages of industry. New mixed attribute-variable RDT plans that compromise demerits of the corresponding zero and zero or one failure plans which are common in practice are developed for the exponential distribution. The proposed mixed plans are compared with the typical RDT plans in terms of probability of acceptance and expected test termination time. A numerical example is provided to illustrate the mixed plans and a procedure to extend these plans to the Weibull distribution with known shape parameter is also presented.

• 기술혁신학회지
• /
• 제8권3호
• /
• pp.887-910
• /
• 2005

This paper attempts to approximate the distribution function for the number of innovation activities (NIA). To this end, the dataset of 2002 Korean Innovation Survey (KIS 2002) published by Science and Technology Policy Institute is used. To deal with zero NTI values given by a considerable number of firms in the KIS 2002 survey, a mixture model of distributions for NIA is applied. The NIA is specified as a mixture of two distributions, one with a point mass at zero and the other with full support on the positive half of the real line. The model was empirically verified for the KIS 2002 data. The mixture model can easily capture the common bimodality feature of the NIA distribution. In addition, when covariates were added to the mixture model, it was found that the probability that a firm has zero NIA significantly varies with some variables.

• Communications for Statistical Applications and Methods
• /
• 제31권1호
• /
• pp.55-64
• /
• 2024

In this study, we consider the sample size determination problem for clustered count data with many zeros. In general, zero-inflated Poisson and binomial models are commonly used for zero-inflated data; however, in real data the assumptions that should be satisfied when using each model might be violated. We calculate the required sample size based on a discrete Weibull regression model that can handle both underdispersed and overdispersed data types. We use the Monte Carlo simulation to compute the required sample size. With our proposed method, a unified model with a low failure risk can be used to cope with the dispersed data type and handle data with many zeros, which appear in groups or clusters sharing a common variation source. A simulation study shows that our proposed method provides accurate results, revealing that the sample size is affected by the distribution skewness, covariance structure of covariates, and amount of zeros. We apply our method to the pancreas disorder length of the stay data collected from Western Australia.

• East Asian mathematical journal
• /
• 제27권1호
• /
• pp.11-21
• /
• 2011

In this paper, we try to extend the viscosity approximation technique to find a particular common zero of a finite family of accretive mappings in a Banach space which is strictly convex reflexive and has a weakly sequentially continuous duality mapping. The explicit viscosity approximation scheme is proposed and its strong convergence to a solution of a variational inequality is proved.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2020년도 전력전자학술대회
• /
• pp.106-108
• /
• 2020

This paper introduces a new pulse-width modulation (PWM) method to reduce common-mode voltages (CMVs) and compare its performance with other reduced CMV-PWM (RCMV-PWM) methods. To avoid the use of zero-vectors which cause high CMV peaks, the introduced method splits every reference vector into two vectors such that the peak-to-peak magnitude of CMV is reduced by one-third of conventional space-vector PWM (SVPWM). The performance of RCMV-PWMs altered by the modulation index are analyzed with simulation results.

• 조명전기설비학회논문지
• /
• 제18권5호
• /
• pp.54-60
• /
• 2004

현대 사회 전반에 걸쳐 개인용 컴퓨터와 같은 비선형 부하가 증가하여, 중성선에는 많은 고조파 전류가 흐른다. 3상 4선식 배전계통을 채용하는 중성선에 과다한 고조파 전류가 흐르면 여러 가지 고조파 장해를 일으킨다. 중성선 고조파 저감 대책으로 지그재그 변압기를 이용하는 영상 필터가 널리 쓰이고 있다. 본 논문에서는 상용화된 중성선 영상 전류 저감장치를 분석하고, 고조파를 저감시키기 위해서 상업용 설비 부하에 적용하고자 한다. 실측한 값과 MATLAB으로 시뮬레이션 한 값을 수치와 그래프로 비교해 보았다.

• 한국콘텐츠학회논문지
• /
• 제11권1호
• /
• pp.9-15
• /
• 2011

제로-워터마킹은 디지털 콘텐츠에 워터마크를 삽입하지 않음으로써 데이터 왜곡과 품질 저하를 피할 수 있는 디지털 워터마킹 기법이다. 이 논문에서는 DCT 영역에서 CRT를 기반으로 한 제로-워터마킹 기법인 DCT0CRT를 제안한다. 무질서한 방식으로 선택된 DCT 블록의 DC 또는 낮은 주파수의 AC 계수들 중에서, 워터마크 정보와 매칭되는 CRT 기반 조건을 만족하는 것을 선택하고, 이러한 선택 정보를 키로 생성함으로써, DCT 영역에서 제로-워터마킹이 가능하도록 지원한다. 이 워터마킹 기법은 이미지에 어떤 변경도 하지 않기 때문에, 이 워터마킹 기법을 적용한 이미지의 품질은 다른 CRT 기반 워커마킹 기법에 비하여 우수하며, 샤프닝, 블러링, JPEG 손실 압축 등을 이용한 공격에도 워터마크가 강인함을 보여준다.