• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.335-338
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• 2012

The present study focuses mainly on modeling the ordinary diffusion flux of species. According to CHEMKIN, both the mixture-averaged approach, Fick's formula, and the full multicomponent approach are implemented in the framework of opensource OpenFOAM. Also the Stefan-Maxwell approach is coded and validated together against measurements of laminar hydrogen jet flame. In the case of viscosity and conductivity of mixture, the mixture-averaged approach is applied and thermal diffusion is not considered in this work. Results show that there are no distinct deviations in three different approaches of diffusion of species in the present hydrogen flame condition.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2004년도 추계학술대회 학술발표 논문집 제14권 제2호
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• pp.543-546
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• 2004

Bishop과 Nabney에 의해 소개된 기존의 혼합 밀도 네트워크(Mixture Density Network)에서는 조건부 확률밀도 함수의 매개변수들(parameters)이 하나의 MLP(multi-layer perceptron)의 출력 벡터로 주어진다. 최근에는 변형된 혼합 밀도 네트워크(Modified Mixture Density Network)라고 하는 이름으로 조건부 확률밀도 함수의 선분포(priors), 조건부 평균(conditional means), 그리고 공분산(covariances) 등이 각각 독립적인 MLP의 출력벡터로 주어지는 경우를 다룬 연구가 보고된 바 있다. 본 논문에서는 조건부 평균이 입력에 관해 선형인 경우를 위한 버전에 대한 이론과 매트랩 프로그램 개발 및 적용을 다룬다. 본 논문에서는 우선 일반적인 혼합 밀도 네트워크에 대해 간단히 설명하고, 혼합 밀도 네트워크의 출력인 다층 퍼셉트론의 매개변수를 각각 다른 다층 퍼셉트론에서 학습시키는 변형된 혼합 밀도 네트워크를 설명한 후, 각각 다른 다층 퍼셉트론을 통해 매개변수를 얻는 것은 동일하나 평균값은 선형함수를 통해 얻는 혼합 밀도 네트워크 버전을 소개한다. 그리고, 모의실험을 통하여 이러한 혼합 밀도 네트워크를의 적용가능성에 대해 알아본다.

• 소성∙가공
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• 제13권2호
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• pp.174-179
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• 2004

The effect of grain refinement on the plastic deformation behaviour of nanocrystalline metallic materials is investigated. A phase mixture model in which a single phase material is considered as an effectively two-phase one is discussed. A distinctive feature of the model is that grain boundaries are treated as a separate phase deforming by a diffusion mechanism. For the grain interior phase two concurrent mechanisms are considered: dislocation glide and mass transfer by diffusion. The proposed constitutive model was implemented into a finite element code (DEFORM) using a semicoupled approach. The finite element method was applied to simulating room temperature tensile deformation of Cu down to the nanoscale grain size in order to investigate the pre- and post-necking behaviour.

• 소성∙가공
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• 제10권5호
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• pp.383-388
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• 2001

In describing the plastic deformation behaviour of ultrafine-grained materials, a phase mixture model in which a polycrystalline material is regarded as a mixture of a crystalline phase and a grain boundary phase has been successful. The deformation mechanism for the grain boundary phase, which is necessary for applying the phase mixture model to polycrystalline materials, is modelled as a diffusional flow of matter along the grain boundary. A constitutive equation for the boundary diffusion creep of the boundary phase was proposed, in which the strain rate is proportional to (stress/grain siz $e^{2}$). The upper limit of the stress of the boundary phase was set to equal to the strength to the amorphous phase. The proposed model can explain the strain rate and grain size dependence of the strength of the grain boundary phase. Successful applications of the model compared with published experimental data are described.

• 한국전산유체공학회지
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• 제14권4호
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• pp.78-85
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• 2009

Cavitating flow simulation is of practical importance for many engineering systems, such as marine propellers, pump impellers, nozzles, injectors, torpedoes, etc. The present work has focused on the simulation of cavitating flow past cylinders with strong side flows. The governing equation is the Navier-Stokes equation based on the homogeneous mixture model. The momentum and energy equation is in the mixture phase while the continuity equation is solved liquid and vapor phase, separately. An implicit dual time and preconditioning method are employed for computational analysis. For the code validation, the results from the present solver have been compared with experiments and other numerical results. A fairly good agreement with the experimental data and other numerical results have been obtained. After the code validation, the strong side flow was applied to include the wake flow effects of the submarine or ocean tide.

• 한국공작기계학회논문집
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• 제12권5호
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• pp.80-87
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• 2003

Air partial pressure ratio and inlet air mass flow are influenced by water vapor and gaseous fuel in mixture on Compressed Natural Gas (CNG) engines. In this paper, the effects of the water vapor and the gaseous fuel that change the air mass flow and the air-fuel ratio are studied. Effective air mass ratio is defined as the air mass flow divided by mixture mass flow, and also it is applied to the estimation of the inlet air mass flow and the air-fuel ratio. The presence of the gaseous fuel and the water vapor in the mixture reduces the air partial pressure and the effective air mass ratio of the CNG engines. The experimental results for the CNG engine show that estimation of the air-fuel ratio based upon the effective air mass ratio is more accurate than that of a normal mode.

• 반도체디스플레이기술학회지
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• 제10권2호
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• pp.1-5
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• 2011

In recent years, worldwide production of solar wafers increased rapidly. Therefore, the solar wafer technology in the developed countries already has become an industry, and related industries such as solar wafer manufacturing equipment have developed rapidly. In this paper we propose the color classification method of the polycrystalline solar wafer that needed in manufacturing equipment. The solar wafer produced in the manufacturing process does not have a uniform color. Therefore, the solar wafer panels made with insensitive color uniformity will fall off the aesthetics. Gaussian mixture models (GMM) are among the most statistically mature methods for clustering and we use the Gaussian mixture models for the classification of the polycrystalline solar wafers. In addition, we compare the performance of the color feature vector from various color space for color classification. Experimental results show that the feature vector from YCbCr color space has the most efficient performance and the correct classification rate is 97.4%.

• 대한토목학회논문집
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• 제41권4호
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• pp.417-428
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• 2021

사회기반시설의 장래유지 관리비용 추정은 불확실한 미래를 다루기 때문에 신뢰성 높은 파손예측모델의 구축이 매우 중요하다. 하지만, 지자체에서는 예산, 인력, 파손예측모델의 필요성 등에 대한 인식부족으로 인해 기반시설의 정확한 파손예측모델 개발이 어려운 실정이다. 따라서 본 연구에서는 베이지안 마르코프 혼합해저드 모델을 활용하여 일반국도 아스팔트 도로포장의 균열률에 대한 지역별 기대수명을 추정하였다. 또한 정확한 기대수명 추정을 위하여 교통량, 축하중, 포장강도, 기후, 제설제사용량 등의 환경변수를 적용하여 추정결과에 대한 신뢰성을 확보하고자 하였다. 분석결과, 지역별로 최소 13.09년에서 최대 19.61년의 기대수명이 추정되었다. 본 연구결과를 활용할 경우, 지역적 파손특성이 고려된 신뢰성 높은 장래 유지관리비용의 추정이 가능할 것으로 기대된다.

• 재활복지공학회논문지
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• 제5권1호
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• pp.95-101
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• 2011

본 논문에서는 의수환자의 일상생활을 고려한 1-자유도 동작을 손을 쥐고 폄으로 정의하고, 두 동작에 대한 근전도 패턴 분류를 위한 가우시안 혼합 모델 기반의 근전도 패턴 분류 알고리즘을 제안한다. 근전도 패턴 분류 알고리즘의 핵심이 되는 근전도 신호의 특징점 추출을 위하여 근전 신호의 진폭 특성을 고려하는 절대차분평균치(DAMV)와 평균절대값(MAV)을 사용한다. 또한 동작에 대한 근전 신호의 진폭 특성을 보다 명확히 구분하기 위하여 D_DAMV와 D_MAV를 제안한다. 본 논문에서는 4명의 성인남성을 대상으로 실험을 실시하였고, 두 동작에 대한 근전도 패턴의 정확한 분류 여부를 확인하였다.

• 복식
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• 제58권7호
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• pp.92-103
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• 2008

The purpose of this study was to subdivide the shoes market in Korea and to evaluate the size and competitive strength of each segment. In order to implement the purpose of this study, the data of 300 respondents were analyzed using CBC(Choice-Based Conjoint measurement) and mixture model. The part-worth utilities were then used to predict the impact of price change on the choice probability using the legit model. As a result, the mixture model showed the optimal segments number and the shoes market in Korea was divided into 4 segments. Each segment was identified by distinctive characteristics such as brands, price and demand for comfortable shoes. Also, as a result of grasping the competitive structure and the competitive strength by sub-markets, one group was sensitive to price according to each competitive situation, whereby the choice probability was greatly influenced, and the other group on the contrary. This study made it clear that discrimination between brands whose profits Increase sharply if price is lowered and brands whose profits do not increase even if price is lowered can help brand managers with their decision-making on price lowering.