• Nuclear Engineering and Technology
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• 제45권6호
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• pp.753-758
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• 2013

A new method of calculating sensitivity coefficients of core characteristics relative to infinite-dilution cross sections has been developed. Conventional sensitivity coefficients are evaluated for the changes of effective cross sections which are dependent on individual models of core and cell. Therefore a correction has been derived to the conventional sensitivity coefficients based on the perturbation theory. The accuracy of the present method has been verified by comparing numerical results of sensitivity coefficients with a reference Monte-Carlo method.

• 한국정보전자통신기술학회논문지
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• 제2권2호
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• pp.23-28
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• 2009

본 연구에서는 뇌파를 AR모델로 모델링하여 선형예측계수를 특징 파라미터로 이용할 때와 뇌파의 주파수 대역별 상호상관계수를 이용할 때의 감정상태 분류 성능을 비교해 보고자 하였다. 이를 위하여 분노, 슬픔, 기쁨, 안정의 4가지 감정상태에 따른 뇌파를 4개 채널로부터 수집하여 선형예측계수와 ${\theta}$, ${\alpha}$, ${\beta}$ 대역의 주파수 영역에서의 상호상관계수를 추출하여 이들을 특징 파라미터로 한 감정상태 분류 실험을 수행함으로써 두 방법의 감정상태 분류 성능을 비교하였고, 패턴 분류기로는 신경회로망을 이용하였다. 감정 분류 실험 결과 뇌파의 특징 파라미터로서 선형예측계수를 이용한 결과가 상호상관계수를 이용할 때보다 성능이 월등히 좋은 것을 알 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 D
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• pp.2815-2817
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• 2001

This study describes the emotion classification using two different feature extraction methods for four-channel EEG signals. One of the methods is linear prediction analysis based on AR model. Another method is cross-correlation coefficients on frequencies of ${\theta}$, ${\alpha}$, ${\beta}$ bands. Using the linear predictor coefficients and the cross-correlation coefficients of frequencies, the emotion classification test for four emotions, such as anger, sad, joy, and relaxation is performed with a neural network. Comparing the results of two methods, it seems that the linear predictor coefficients produce the better results than the cross-correlation coefficients of frequencies for-emotion classification.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.494-497
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• 2004

To date the KOMPSAT OSMI(Ocean Scanning Multi-spectral Imager) data have been widely used in natural disaster monitoring such as Typhoon, Asian Dust, Red Tide, and Forest Fire. Quantitative analyses related to the marine ecosystem have been delayed because they require good quality of data through Cal/Val activities. To resolve such problem, KARI performed the OSMI crosscalibration study with SeaWiFS team. In this study, we will demonstrate the OSMI ocean color products with updated cross-calibration coefficients and compare them to the previous cross-calibration results.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.141-144
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• 2001

An accurate cross sections set are necessary for the quantitatively understanding and modeling of plasma phenomena. By using the electron swarm method. we determine an accurate electron cross sections set for objective atoms or molecule at low electron energy range. In previous paper, we calculated the electron transport coefficients in pure $CF_4$ molecular gas by using two-term approximation of the Boltzmann equation. And by using this simulation method. we confirmed erroneous calculated results of transport coefficients for $CF_{4}$ molecule treated in this paper having 'C2v symmetry' as $C_{3}H_{8}$ and $C_{3}F_{8}$ which have large vibrational excitation cross sections which may exceed elastic momentum transfer cross section. Therefore, in this paper, we calculated the electron transport coefficients(W and $ND_L$) in pure $CF_4$ gas by using multi-term approximation of the Boltzmann equation by Robson and Ness which was developed at lames-Cook university, and discussed an application and/or validity of the calculation method by comparing the calculated results by two-term and multi-term approximation code.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.141-144
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• 2001

An accurate cross sections set are necessary for the quantitatively understanding and modeling of plasma phenomena. By using the electron swarm method, we determine an accurate electron cross sections set for objective atoms or molecule at low electron energy range. In previous paper, we calculated the electron transport coefficients in pure CF$_4$ molecular gas by using two-term approximation of the Boltzmann equation. And by using this simulation method, we confirmed erroneous calculated results of transport coefficients for CF$_4$ molecule treated in this paper having 'C2v symmetry'as C$_3$H$_{8}$ and C$_3$F$_{8}$ which have large vibrational excitation cross sections which may exceed elastic momentum transfer cross section. Therefore, in this paper, we calculated the electron transport coefficients(W and ND$_{L}$) in pure CF$_4$ gas by using multi-term approximation of the Boltzmann equation by Robson and Ness which was developed at James-Cook university, and discussed an application and/or validity of the calculation method by comparing the calculated results by two-term and multi-term approximation code.e.

• 한국산학기술학회논문지
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• 제19권4호
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• pp.623-632
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• 2018

본 논문은 최적설계기법을 적용하여 Cross-WLF 모델의 계수 값을 효과적으로 추정하는 것이다. 사출성형 공정의 해석에서 주로 사용되는 Cross-WLF 점도 모델은 온도와 전단율의 영향이 민감한 고분자의 유변학적 특성을 잘 모사하는 모델로 널리 사용되고 있다. 정확한 폴리머 유변학적 특성 예측을 위해서는 정확한 Cross-WLF 계수 값의 추정은 필수이다. 실험적으로 획득한 데이터의 점도 값과 Cross-WLF의 계수 값을 설계변수로 가정하여 계산한 점도 값이 일치한다면, 최적화 기법을 통해 정의된 Cross-WLF모델이 실험 데이터를 정확하게 모사하는 것이라 할 수 있다. 이러한 Cross-WLF 모델을 통해 계산된 점도와 실험 데이터의 차이를 최소화하는 목적함수로 Cross-WLF의 계수 값을 설계변수로 정의하여 연구를 수행하였다. 본 논문에서 제시한 최적화기법의 타당성으로 확인하기 위하여 몇개의 소재를 대상으로 하여 Moldflow에서 제공하는 Cross-WLF 계수 값과 본 논문에서 제안한 방법으로 획득한 계수 값를 비교하여 잘 일치함을 확인하였다. 또한, Moldflow Plastic Lab의 실제 측정 데이터를 활용하여 추정한 결과 제안한 방법의 효율성 및 타당성을 입증하였다.

• E2M - 전기 전자와 첨단 소재
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• 제8권6호
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• pp.685-692
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• 1995

The electron transport coefficients in argon gas is studied over the range of E/N values from 85 to 566 Td by the Monte Carlo method considering the latest cross section data. The result of the Monte Carlo method analysis shows that the value of the electron transport coefficients such as the electron drift velocity, the ratio of the longitudinal and transverse diffusion coefficients to the mobility. It is also found that the electron transport coefficients calculated by the two-term approximation analysis agree well with those by Monte Carlo calculation. The electron energy distributions function were analysed in argon at E/N=283, and 566 Td for a case of the equilibrium region in the mean electron energy. A momentum transfer cross section for the argon atom which was consistent with both of the present electron transport coefficients was derived over the range of mean electron energy from 10.3 to 14.5 eV, also suggested as a set of electron cross section for argon atom. The validity of the results obtained has been confirmed by a Monte Carlo simulation method.

• Wind and Structures
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• 제31권3호
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• pp.209-216
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• 2020

Aiming at the wind-resistant design of a sea-crossing arch bridge, the static aerodynamic coefficients of its girder (composed of stretches of π-shaped cross-section and box cross-section) were studied by using computational fluid dynamics (CFD) numerical simulation and wind tunnel test. Based on the comparison between numerical simulation, wind tunnel test and specification recommendation, a combined calculation method for the horizontal force coefficient of intermediate and small span bridges is proposed. The results show that the two-dimensional CFD numerical simulations of the individual cross sections are sufficient to meet the accuracy requirements of engineering practice.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.583-589
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• 2004

One of noticeable features in the cross flow fan is that a working fluid passes through impeller blade twice without distinction between the inlet and exit angles. Also, it does produce higher circumferential velocity than other types of blade at the same flow rate in accordance with the application of the forward curved shape. However, a design theory for the cross-flow fan has not yet been formed owing to an eccentric vortex, which is the remarkable characteristics, occurred in a cross-flow fan. Furthermore, the eccentric vortex, which is difficult to control of the size and position, is the important cause of performance decrease. In this study, experiments are carried out to estimate the similarity of the cross-flow fan with various scales and rotational velocity changes. Pressure coefficients to flow coefficients with various scales of the cross-flow fan are plotted to research the application of the general similarity law of the turbomachinery in the cross-flow fan with Archimedes spital, which is the important factor haying an effect on it.