• Journal of Welding and Joining
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• 제23권1호
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• pp.48-54
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• 2005

Laser keyhole welding is investigated using a three-dimensional Gaussian heat source, and the heat source parameters such as the keyhole depth, welding efficiency and power density distribution factor are determined in a systematic way. For partial penetration, the keyhole depth is same as the penetration and is predicted using the experimental data. The welding efficiency is calculated using the ray-tracing method and the power density distribution factor is determined from the bead shape. Full penetration is classified into the transition, normal and excessive modes depending on the degree of keyhole opening. Thermal analysis of the bead-on-plate welds is conducted using the Gaussian heat source, and the calculated weld geometries show reasonably good agreements with the experimental results.

• Journal of the Korean Data and Information Science Society
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• 제27권3호
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• pp.803-814
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• 2016

Recent times have seen an exponential increase in the amount of spatial data, which is in many cases associated with temporal data. Recent advances in computer technology and computation of hierarchical Bayesian models have enabled to analyze complex spatio-temporal data. Our work aims at modeling data of daily average nitrogen dioxide (NO2) levels obtained from 25 air monitoring sites in Seoul between 2003 and 2010. We considered an independent Gaussian process model and an auto-regressive model and carried out estimation within a hierarchical Bayesian framework with Markov chain Monte Carlo techniques. A Gaussian predictive process approximation has shown the better prediction performance rather than a Hierarchical auto-regressive model for the illustrative NO2 concentration levels at any unmonitored location.

• Journal of Welding and Joining
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• 제22권2호
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• pp.69-77
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• 2004

The Gaussian heat source has been widely used to simulate the heat flux of the welding we, and applied to calculating the temperature distribution of a workpiece. The conventional two-dimensional Gaussian heat source for the GMAW is modified in this work by decomposing the arc heat into heats of the cathode and metal transfer. The efficiency and effective arc radius of each heat source are determined analytically for the free-flight mode such as the globular and spray modes. The temperature distribution and weld geometry are calculated using the finite element method, and distribution of the drop heat is found to have significant effects on the penetration. The predicted results show good agreements with the available experimental results, especially with the penetration.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.225-228
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• 2007

This paper presents a geostatistical methodology to model local uncertainty in spatial estimation of sediment grain size with high-resolution remote sensing imagery. Within a multi-Gaussian framework, the IKONOS imagery is used as local means both to estimate the grain size values and to model local uncertainty at unsample locations. A conditional cumulative distribution function (ccdf) at any locations is defined by mean and variance values which can be estimated by multi-Gaussian kriging with local means. Two ccdf statistics including condition variance and interquartile range are used here as measures of local uncertainty and are compared through a cross validation analysis. In addition to local uncertainty measures, the probabilities of not exceeding or exceeding any grain size value at any locations are retrieved and mapped from the local ccdf models. A case study of Baramarae beach, Korea is carried out to illustrate the potential of geostatistical uncertainty modeling.

• 응용통계연구
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• 제30권2호
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• pp.203-213
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• 2017

우리는 이변량 경시적 자료의 조건부 결합 분포를 추정하기 위하여 회귀 모형과 코플라 모형을 연구하였다. 주변 분포의 추정을 위하여 시변 변환 모형을 고려하였고, 이변량 반응변수 각각에 대한 주변 분포를 가우시안 코플라를 이용하여 결합하여 조건부 결합 분포를 추정하였다. 우리가 제안한 모형은 조건부 평균 모형만으로 자료를 설명하기 어려운 경우에 적용될 수 있다. 시변 변환 모형과 가우시안 코플라 모형을 결합한 본 논문의 방법은 반복 측정된 이변량 경시적 자료에 대한 모형화가 용이하며 해석하기 쉬운 장점이 있다. 우리는 본 논문의 방법을 반복 측정된 이변량 콜레스테롤 자료를 분석하는데 적용하여 보았다.

• 한국통신학회논문지
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• 제37권6A호
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• pp.473-479
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• 2012

본 논문에서는 가우시안 2-군집 모델을 사용한 블라인드 등화 방법을 제안한다. 제안 방식에서는 M-QAM 수신 신호를 가우시안 분포하는 2-군집으로 모델링하여 계산 복잡성을 최소화하고 신호 추정의 신뢰도를 높였다. 여기에 가변 파라미터 비선형 추정기를 사용하여 송신 신호를 추정하고, 신호 추정 시 군집의 분산에 따라 축소신호점과 원신호점을 선택적으로 적용하여 신호 추정의 신뢰도를 더욱 개선하였다. 결과적으로 제안 방식은 등화기의 계산 복잡성을 단순화하면서 성능을 개선하였다. 모의실험을 통해 64-QAM의 고차 신호에 대한 블라인드 등화에서 제안 방식이 기존 방식에 비해 우수한 성능을 보임을 확인하였다.

• 한국군사과학기술학회지
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• 제22권1호
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• pp.27-34
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• 2019

This paper presents a chamber pressure model development of K2 rifle by applying Gaussian mixture model. In order to materialize a real recoil force of a virtual reality shooting rifle in military combat training, the chamber pressure which is one of major components of the recoil force needs to be investigated and modeled. Over 200,000 data of the chamber pressure were collected by implementing live fire experiments with both K100 and M193 of 5.56 mm bullets. Gaussian mixture method was also applied to create a mathematical model that satisfies nonlinear, asymmetry, and deviations of the chamber pressure which is caused by irregular characteristics of propellant combustion. In addition, Polynomial and Fourier Regression were used for comparison of results, and the sum of squared errors, the coefficient of determination and root-mean-square errors were analyzed for performance measurement.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2001년도 가을 학술발표논문집 Vol.28 No.2 (2)
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• pp.169-171
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• 2001

이 논문에서 논해지는 음성변환이라는 것은 어떤 화자의 음성(소스)을 다른 화자의 음성(타겟)으로 바꾸는 것이다. 이 때, 모든 음소들을 녹음해서 데이터베이스화한 음성끼리 매칭시키는 것이 아니라, 몇 번의 학습을 통하여 음색의 특징을 파악한 후 나온 변환함수를 이용하여 원래 화자의 음성을 타겟 음성으로 변환하는 시스템을 제안하고자 한다. 여기서, 음색의 특징들을 추출한 후, 변환함수를 만들기 위한 트레이닝을 위한 방법으로 Gaussian Mixture Modeling을 이용할 것이다.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2003년도 ISIS 2003
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• pp.86-89
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• 2003

To model a numerical problem space under the limitation of available data, we need to extract sparse but key points from the space and to efficiently approximate the space with them. This study proposes a sampling method based on the search process of genetic algorithm and a space modeling method based on least-squares approximation using the summation of Gaussian functions. We conducted simulations to evaluate them for several kinds of problem spaces: DeJong's, Schaffer's, and our original one. We then compared the performance between our sampling method and sampling at regular intervals and that between our modeling method and modeling using a polynomial. The results showed that the error between a problem space and its model was the smallest for the combination of our sampling and modeling methods for many problem spaces when the number of samples was considerably small.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.489-492
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• 2007

The P-wave velocity at the formation which contains gas hydrate varies very wide upon gas hydrate existence. These features on seismic shot gather can not be simulated normally by numerical modeling of homogeneous medium so that we need that of random inhomogeneous medium instead. We, in this study generated random inhomogeneous medium using gaussian ACF, exponential ACF and von Karman ACF and that we supposed the random inhomogeneous medium be gas hydrate formation to execute numeric modeling. The modeling result shows the typical effect by scattering caused by random hydrate formation as is observed from seismic shot gather where hydrate exist.