• 오토저널
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• 제11권3호
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• pp.60-71
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• 1989

In this paper the structure of an engine and its interaction are investigated by a mathematical model for the performance evaluation. The total system is composed of air-fuel inlet element, intake manifold, combustion, engine dynamics and emission. Their control functions are schematically evaluated. Because of the model constructure with general engine functions and computer simulation of the chosen engine, physical characteristics of the corresponding engine and the engine data of normal operation states are used. According to the study, it is possible to predict the mixture rate by the difference in the mass of fuel and air flowing into cylinder and to evaluate and trace dynamic characteristic of operation state under various operating conditions. The model characteristic under the transient operating condition to evaluate operating of actual engine through the result of simulation.

• 한국통계학회:학술대회논문집
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• 한국통계학회 2003년도 추계 학술발표회 논문집
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• pp.9-14
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• 2003

A Bayesian model-based clustering method is proposed for clustering objects on the basis of dissimilarites. This combines two basic ideas. The first is that tile objects have latent positions in a Euclidean space, and that the observed dissimilarities are measurements of the Euclidean distances with error. The second idea is that the latent positions are generated from a mixture of multivariate normal distributions, each one corresponding to a cluster. We estimate the resulting model in a Bayesian way using Markov chain Monte Carlo. The method carries out multidimensional scaling and model-based clustering simultaneously, and yields good object configurations and good clustering results with reasonable measures of clustering uncertainties. In the examples we studied, the clustering results based on low-dimensional configurations were almost as good as those based on high-dimensional ones. Thus tile method can be used as a tool for dimension reduction when clustering high-dimensional objects, which may be useful especially for visual inspection of clusters. We also propose a Bayesian criterion for choosing the dimension of the object configuration and the number of clusters simultaneously. This is easy to compute and works reasonably well in simulations and real examples.

• 대한전기학회논문지
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• 제38권9호
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• pp.724-732
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• 1989

The structure of engine and its interaction are investigated and the construction of mathematical model for the performance evaluation is presented and then simulated. The total system is classified as air-fuel inlet element, intake manifold, combustion, and engine dynamics and their control function are schematically evaluated. Because of the model structure with general engine function and computer simulation of the chosen engine, physical characteristics of the corresponding engine and the engine data of normal operation state are used. According to the study, it is possible to predict the mixture rate by by the difference in the mass of fuel and air into cylinder and to evaluate and trace dynamic characteristic of operation state under various operating condition. The model characteristic under the transient operating condition makes it possible to effectively evaluate the operation of actual engine through the result of simulation.

• 응용통계연구
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• 제31권5호
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• pp.555-572
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• 2018

영상처리 분야의 중요한 주제인 영상의 잡음 제거 과정은 원래의 순수한 영상이 다양한 원인으로 발생한 잡음에 의해 오염되었을때 이 잡음을 제거하거나 줄이는 것을 의미한다. 잡음 제거 과정에서는 영상에 추가된 잡음과 원 영상이 가진 고유한 특징들을 구별해내는 것이 중요하며 이에 대한 많은 연구가 진행되고 있다. 적응적 필터와 시그마 필터는 잡음 제거를 위하여 사용하는 대표적인 잡음 제거 필터이며 이 필터들의 효용성은 정확한 잡음 추정에 영향을 받는다. 따라서 본 연구에서는 디리클레 정규 혼합모형을 토대로 영상을 오염시키고 있는 잡음의 분포를 생성하고 이를 토대로 영상의 특징과 잡음을 구별하기 위한 베이지안 방법을 제시한다. 특히 잡음의 분포와 특징의 분포를 구별하기 위해 베이지안 추론을 전개하고 영상에 포함된 잡음을 제거하는 알고리즘을 제시하고자 한다.

• 대한기계학회논문집
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• 제19권8호
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• pp.1989-1998
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• 1995

Characteristics of the flame propagation for normal and abnormal combustion in hydrogen premixture in a cylindrical constant-volume combustion chamber are studied numerically. A detailed hydrogen oxidation kinetic mechanism, mixture transport properties and a model describing spark ignition process are used. The calculated pressure-time history of the stable deflagration wave propagation agrees well with the experiment. The ignition of the premixture in the unburned gas, initiated by the hot spot, causes a transition from deflagration to detonation under some initial temperature and pressure. Under the initial conditions with high temperature and pressure, excessive ignition energy initiates a strong blast wave and a detonation wave that follows. The chemical reaction in the detonation wave is much more vigorous than that in the deflagration wave and the peak pressure in the detonation wave is much higher than the equilibrium value.

• 대한산업공학회지
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• 제14권2호
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• pp.63-70
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• 1988

Recently a new regime, called "back school" is advocated for the purpose of rapidly and economically returning a patient to full functional fitness and normal occupational activities. Assuming that this functional and vocational restoration is a goal of a regabilitation program, it is apparent that early recovery and higher success rate are major concern. In this study, a mixture model is developed and used to evaluate the recovery process of low back pain (LBP) patients in a rehabilitation program. The model provides (1) the probability of being recovered, and (2) the rate of recovery. Patients with gradual onset, with higher education, or of young age tend to show better prognosis.

• 한국멀티미디어학회논문지
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• 제11권5호
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• pp.597-609
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• 2008

기존의 배경 모델링 방법은 배경 모델의 반복적 갱신(recursive update)으로 인해 배경보다 객체가 더 자주 등장하는 혼잡한 환경에서는 정확한 배경 모델링을 생성하기 어려운 문제를 지니고 있다. 본 논문은 이러한 기존 방법의 문제를 해결하기 위해 기존의 혼합 Gaussian 모델을 기반으로 하는 적응적 배경 모델링 방법을 제안한다. 제안한 방법은 영상 내 전경 영역의 비율에 따라 배경 모델의 학습 비율을 적응적으로 조절한다. 따라서, 혼잡 상황에서는 배경 모델의 갱신을 억제하여 배경 모델을 잘 유지시키는 것이 가능하다. 실험을 통해 제안한 방법이 일반적인 상황의 영상에서는 기존 방법과 유사한 정확도를 보이지만 혼잡한 상황에서는 기존 방법과 비교하여 배경 제거를 효과적으로 수행하는 것을 확인하였으며, 또 정확도 측정 결과 혼잡한 상황의 영상에서 기존 방법과 비교하여 F 값이 5-10% 가량 향상함을 확인하였다.

• Korea-Australia Rheology Journal
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• 제15권1호
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• pp.35-41
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• 2003

It is expected that particle size distribution of any portion obtained through screening, is of more uniform than that of the original mixture, typically following such as log-normal, Rosin-Rammler distributions and so on. In this study, therefore, a new relation between parameters of the uniform distribution and flow characteristics of the coarse particle suspensions is derived based on the continuous polydisperse model (Ookawara and Ogawa, 2002b), which is derived from the discrete polydisperse model (Ookawara and Ogawa,2002a). The derived model equation predicts a linear increase of viscosity with shear rate, viz., dilutant flow characteristics. Further, the increase of viscosity is expected to be proportional to the square of volume fraction of particles, and to show the linear dependency on density and average diameter of particles. It is also shown that the uniform distribution model includes additional term that expresses the effect of distribution width. For verification of the model, the experimental results of Clarke (1967) are cited as well as in our previous work for the monodisperse model (Ookawara and Ogawa,2000) since most parameters were varied independently in his work. It is suggested that the newly introduced term expands the applicable range compared with the monodisperse model.

• 동의생리병리학회지
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• 제21권6호
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• pp.1549-1554
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• 2007

To verify the effects of JAUN-1, which is a water-extracted herbal mixture, on gastroenteric disorders induced by 0.1 percent of iodoacetamide (IA) in rats. We divided four groups, $Na{\"{\i}}ve$ + Distilled Water (DW), 0.1% IA + DW, 0.1% IA + Proton pump inhibitor (Lansoprazole, 5 mg/kg) and 0.1% IA + Herbal mixture (JAUN-1, 50mg/kg) and performed following experimental methods to confirm its advantageous effects against ulcerogenic stomach in rats induced by 0.1% IA; cell cytotoxicity, analysis of lesions score, Hematoxylin & Eosin (H&E) stain, RT-PCR for ${\beta}-actin$, COX-1 and COX-2 and evaluation of intestinal prokinetic activity. No cytotoxicity was elucidated at the concentration of 1, 5, 10, 50, 100, $500\;{\mu}g/ml$ and 1mg/ml JAUN-1 through MTT Assay using by human stomach epithelial AGS cells, respectively. In addition, the JAUN-1 treated group and the lansoprazole treated group significantly decreased in lesions score compared to the DW treated group in the gastritis induced rat model, and results of immunohistochemistry by H&E staining showed that histological recovery in Proton Pump Inhibitor (PPI) and JAUN-1 treated groups rather than the DW administrated group. Another outcome was that ${\beta}-actin$ relative COX-2 expression level was significantly promoted in the DW treated group while ${\beta}-actin$ relative COX-1 expression level was no meaningful change in this rat model. Finally, intestinal prokinetic activity was recovered from low level of prokinetic activity due to 0.1% IA induced gastritis to the similar level of Normal group. These results suggested that JAUN-1 may have beneficial effects against 0.1% IA-induced gastritis rat model through decreasing lesions score, histological recovery, ${\beta}-actin$ relative COX-1, 2 expression level and prokinetic activity.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2003년도 춘계학술대회논문집
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• pp.129-134
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• 2003

In this paper, we determine optimal reduction in the lead time and setup cost for some stochastic inventory models. And we propose more general model that allow the backorder rate as a control variable. We first assume that the lead time demand follows a normal distribution. And we assume that the backorder rate is dependent on the length of lead time through the amount of shortages. The stochastic models analyzed in this paper are the classical continuous and periodic review policy models with a mixture of backorders and lost sales. For each of these models, we provide a sufficient conditions for the uniqueness of the optimal operating policy. We also develop algorithms for solving these models and provide illustrative numerical examples.