• Communications for Statistical Applications and Methods
• /
• 제28권5호
• /
• pp.425-445
• /
• 2021

A generalization of the log-logistic (LL) distribution called exponentiated log-logistic (ELL) distribution on lines of exponentiated Weibull distribution is considered. In this paper, based on progressive type-II censored samples, we have derived the maximum likelihood estimators and Bayes estimators for three parameters, the survival function and hazard function of the ELL distribution. Then, under the balanced squared error loss (BSEL) and the balanced linex loss (BLEL) functions, their corresponding Bayes estimators are obtained using Lindley's approximation (see Jung and Chung, 2018; Lindley, 1980), Tierney-Kadane approximation (see Tierney and Kadane, 1986) and Markov Chain Monte Carlo methods (see Hastings, 1970; Gelfand and Smith, 1990). Here, to check the convergence of MCMC chains, the Gelman and Rubin diagnostic (see Gelman and Rubin, 1992; Brooks and Gelman, 1997) was used. On the basis of their risks, the performances of their Bayes estimators are compared with maximum likelihood estimators in the simulation studies. In this paper, research supports the conclusion that ELL distribution is an efficient distribution to modeling data in the analysis of survival data. On top of that, Bayes estimators under various loss functions are useful for many estimation problems.

• Structural Engineering and Mechanics
• /
• 제33권6호
• /
• pp.657-674
• /
• 2009

In this paper a 3-D continuum damage mechanics formulation for composite laminates and its implementation into a finite element model that is based on the layer-wise laminate plate theory are described. In the damage formulation, each composite ply is treated as a homogeneous orthotropic material exhibiting orthotropic damage in the form of distributed microscopic cracks that are normal to the three principal material directions. The progressive damage of different angle ply composite laminates under quasi-static loading that exhibit the free edge effects are investigated. The effects of various numerical modeling parameters on the progressive damage response are investigated. It will be shown that the dominant damage mechanism in the lay-ups of [+30/-30]s and [+45/-45]s is matrix cracking. However, the lay-up of [+15/-15] may be delaminated in the vicinity of the edges and at $+{\theta}/-{\theta}$ layers interfaces.

• 한국게임학회 논문지
• /
• 제7권4호
• /
• pp.53-62
• /
• 2007

래디오시티(radiosity)는 디퓨즈 반사(diffuse reflection)를 효과적으로 표현하는 전역조명(global illumination) 방법으로 공간 및 물체 표면간의 에너지 교환을 모델링한다. 그러나 많은 계산량으로 인해 실시간 활용에는 제약이 존재하며, 이를 해결하기 위해 GPU(Graphics Processing Unit) 기반의 래디오시티 알고리즘이 제안되고 있다. 본 논문에서는 G. Coombe 등이 제안한 GPU 기반의 점진적 세분(progressive refinement) 래디오시티를 구현하고 HDR(High Dynamic Range) 래디언스(radiance) 맵으로 구성된 3차원 공간에 적용하여 사실적인 합성영상을 렌더링하였다. 대상 공간과 조명환경을 HDR 래디언스 맵으로 구성함으로써 영상기반(image-based) 방법의 장점인 대상 장면의 복잡도와 관계없는 결과 영상을 생성할 수 있었다 환경맵을 이루는 각 텍셀(texel)의 해상도 설정 및 밉매핑(mipmaping)의 적용에 따라 다양한 실험 결과를 분석하였으며, 기존의 HDR 레디언스 맵과 GPU를 이용한 증분 래디오시티 방법과의 비교를 통해 본 시스템의 개선된 렌더링 성능을 확인하였다.

• 문화기술의 융합
• /
• 제9권3호
• /
• pp.579-585
• /
• 2023

본 연구의 목적은 텍스트네트워트분석을 통해 스토킹에 대한 정치성향의 언론기사 내에 핵심 단어를 탐색하고 내재된 의도를 살펴보는 것이다. 2018년 1월 1일부터 2022년 12월 31일까지 보도된 보수언론기사(조선일보, 중앙일보) 824건, 진보언론기사(한겨레신문, 경향신문) 783건으로 총 1,607건을 선정하여 LDA(Latent Dirichlet Allocation) 기반의 토픽모델링 기법으로 도출된 주제범주의 양상을 탐색하였다. 연구결과는 보수언론과 진보언론의 공통된 토픽은 젠더폭력의 인식개선, 신변보호 및 처벌강도, 스토커 신상공개 도출되었고 두 언론의 상이한 토픽은 보수언론에서는 스토커의 가해행위, '신당역 살인사건'의 개요와 진보언론은 '신당역 살인사건'의 가중처벌요구, (사이버공간의) 성착취 범죄 근절로 구성되었다. 본 연구는 스토킹에 대한 언론기사 간의 이념적 의견에 따라 보도형태에 변화가 있음을 시사한다.

• Composites Research
• /
• 제30권2호
• /
• pp.149-157
• /
• 2017

본 논문에서는 응집영역 모델링 기법을 사용하여 노치가 있는 적층복합재료의 파괴거동을 연구하였다. 먼저 노치가 있는 적층복합재료 시편형상에 대해 일반 3차원 고체요소로 모델링 한 후 요소들 사이에 섬유파괴, 기지파괴 및 층간분리 파괴를 담당하는 응집요소를 삽입하여 유한요소 메쉬를 제작하였다. 다음으로 일축인장 시험을 모사하는 하중 및 경계조건을 가하여 점진적 파괴해석을 수행하고 해석결과를 참고문헌의 실험결과와 비교하여 해석의 타당성을 검증하였다. 수치해석 결과로부터 노치가 있는 적층복합재료 인장시편의 파괴시작 및 진전거동을 분석하였으며 파괴모드의 진전을 체계적으로 조사하였다.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2007년도 정기 학술대회 논문집
• /
• pp.441-444
• /
• 2007

This paper presents a part of micormechanics-based elastic modeling (Lee and Pyo, 2007) of particle-reinforced composites containing slightly weakened interfaces. The Eshelby's tensor for a damaged ellipsoidal inclusion to model particles with slightly weakened interfaces is incorporated into a micormechanical formulation by Ju and Chen (1994). A damage model in accordance with the Weibull's probabilistic function is also developed to simulate the progression of weakened interface in the composites.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
• /
• pp.211-214
• /
• 2005

The analytical model capable of predicting stress vs. strain relations for circular FRP-confined concrete in a rational manner is proposed. The underlying idea is that the volumetric expansion due to progressive microcracking is an important measure of the extent of damage in the material microstructure. Various existing analytical models including the proposed were also investigated, and compared each other and with test results.

• 한국방송∙미디어공학회:학술대회논문집
• /
• 한국방송공학회 1999년도 KOBA 방송기술 워크샵 KOBA Broadcasting Technology Workshop
• /
• pp.195-200
• /
• 1999

In computer graphics, the modeling and simulation of flames is a challenging problem. In this paper, we propose an approach for the simulation of a fire disaster. We use particle systems to describe the dynamic behavior fire. The illumination of dynamic flame is rendered by progressive radiosity algorithm.

• 대한조선학회논문집
• /
• 제40권6호
• /
• pp.30-36
• /
• 2003

To improve survivability of damaged ship, assessment of stability and structural safety, and behavior analysis in wave is required. Prediction of sinking time, damage stability and structural strength considering progressive flooding and dynamic force in wave is very important. To do it, a geometric model which can be express damaged ship is prepared. This paper described the geometric modeler for survivability assessment of damaged ship. The modeler is developed based on 3-D geometric modeling kernel, ACIS. The hull form and compartment definition is available fundamentally. And requirement for modeler contains data generation and interface for hydrostatic calculation, behavior analysis, and longitudinal strength analysis and so on. To easy access modeling system by conventional user such as crew, user interface is developing.

• Computers and Concrete
• /
• 제27권4호
• /
• pp.297-304
• /
• 2021

The hybrid Finite-Discrete Element (FDEM) approach combines aspects of both finite elements and discrete elements with fracture mechanics principles, and therefore it is well suited for realistic simulation of quasi-brittle materials. Notwithstanding, in the literature its application for the analysis of concrete is rather limited. In this paper, the proprietary FDEM code ELFEN is used to model concrete specimens under uniaxial compression and indirect tension (Brazilian tests) of different sizes. The results show that phenomena such as size effect and influence of strain-rate are captured using this modeling technique. In addition, a preliminary model of a slab subjected to dynamic shear punching due to progressive collapse is presented. The resulting fracturing pattern of the impacted slab is similar to observations from actual collapse.