• Nuclear Engineering and Technology
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• v.5 no.4
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• pp.265-278
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• 1973

The incoherent neutron scattering cross section of molecular liquids is analyzed using a damping function model for correlation functions of molecular translations and rotations. The present approach is different from recent works in that the scattering function is evaluated directly, not through the intermediate scattering function. The damping fuction is determined from a simple relation between its long-wavelength limit and the generalized frequency distribution function, and translation-rotation couplings are assumed to be neglected. A physical model is used for the translational motions of center-of-mass of a molecule, including properly its short-time and long-time behaviors. A simple model for the rotational motions is suggested which relates the damping function to the Fourier transform of the dipole correlation function, or equivalently, the infrared vibrational absorption spectrum. Theoretical absolute scattering intensities are computed for liquid methane and shown to be in satisfactory agreement with both thermal and cold neutron measurements.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.119-122
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• 2005

정규식생지수는 일반적으로 식생의 활력도를 나타나는 지표로서 널리 사용되고 있다. 최근에는 정규식생지수가 특정지역의 강우량과 온도의 계절 및 경년변화와 어떤 상관관계를 가지며 기후변화는 식생지수에 어떠한 영향을 미치는지 등에 관한 연구가 활발히 수행되고 있다. 본 연구에서는 1981년부터 2001년까지의 NOAA/AVHRR 영상으로부터 계산된 남한지역 정규식생지수의 주성분 분석을 통해 자료의 공간변화패턴을 분석하고 경험적 직교함수를 이용하여 시간적 변화 양상을 파악하였다. 분석결과 정규식생지수의 공간변화도는 첫 주성분에 의하여 약 $60\%$ 정도 설명되어지며 첫 주성분은 남한지역의 지형 자료 패턴을 따르고 두 번째 주성분은 전체 변화도의 약 $17\%$를 나타내며 강한 남북기울기를 보여주는 것은 계절변화와 상관한 위도변화에 따른 정규식생지수의 변화를 나타낸다. 그리고 소양강댐 및 안동댐 유역의 정규식생지수, 강우량 및 유입량 상관관계 분석 결과 정규식생지수의 계절변화와 경년변화는 강우량의 변화에 그리 민감하지 않은 것으로 나타났다.

• Nuclear Engineering and Technology
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• v.19 no.2
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• pp.77-84
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• 1987

Statistical evaluation for the heat transfer correlation in the containment subcompartments is carried out from HDR experimental data. Heat transfer data for three HDR blowdown tests, V.42, V.43 and V.44, are analyzed to deduce the correlation. As Uchida already proposed, air-to-steam density ratio is proven to be the most affecting parameter in this study. Here Uchida heat transfer correlation is revised by including temperature difference between the atmosphere and the wall surface, and atmospheric pressure. In addition to these dependencies, atmospheric turbulence and time factor may be included in the model. This implication, however, is not successful, because turbulence and transient phenomena were not adequately quantified in the HDR program. It is concluded that a strong correlation exists between the heat transfer coefficient and temperature differences, specially for forced circulation conditions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.1
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• pp.62-68
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• 1993

During compression molding of fibre-reinforced thermoplastics, the two main problems such as the fibre-matrix separation and the fibre orientation are produced by the flow state. As the molded product tends to be nonhomogeneous and anisotropic due to the separation and the orientation, it is necessary to clarify these in relation to the molding process variables and the fibre structure (fibre entanglement). If the entanglement of fibre structure is strong, the separation increases and the orientation is not easily aligned. Namely, these are inseparably related to each other. The correlation between the separation and the orientation have to be clarified for designing the fibre structure. In this paper, the degree of nonhomogeneity which is a measure of the separation is obtained using one-dimensional rectangular shaped part compression molding. And the orientation function is defined and measured by the image processing using soft X-rayed photograph and image scanner. Correlation between the degree of nonhomogeneity and the orientation function is discussed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.5
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• pp.526-534
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• 2014

In this study, single-input transfer function model is applied to forecast monthly mean sea surface temperature(SST) in 2010 at Yeosu in Korean coastal waters. As input series, monthly mean air temperature series for ten years(2000-2009) at Yeosu in Korea is used, and Monthly mean SST at Yeosu station in Korean coastal waters is used as output series(the same period of input). To build transfer function model, first, input time series is prewhitened, and then cross-correlation functions between prewhitened input and output series are determined. The cross-correlation functions have just two significant values at time lag at 0 and 1. The lag between input and output series, the order of denominator and the order of numerator of transfer function, (b, r, s) are identified as (0, 1, 0). The selected transfer function model shows that there does not exist the lag between monthly mean air temperature and monthly mean SST, and that transfer function has a first-order autoregressive component for monthly mean SST, and that noise model was identified as $ARIMA(1,0,1)(2,0,0)_{12}$. The forecasted values by the selected transfer function model are generally $0.3-1.3^{\circ}C$ higher than actual SST in 2010 and have 6.4 % mean absolute percentage error(MAPE). The error is 2 % lower than MAPE by ARIMA model. This implies that transfer function model could be more available than ARIMA model in terms of forecasting performance of SST.

• Tribology and Lubricants
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• v.12 no.2
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• pp.48-54
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• 1996

제철산업과 광산산업에서 난연성 압축유로써 Water-in-oil(W/O) 에멀젼의 사용이 점차 증가하고 있다. 이러한 관점에서, 기유의 점도, 물과 오일의 배합비율 및 음이온성 emulsifier의 농도 변화에 따른 W/O 에멀젼의 점도, 안정성 및 내마모성을 조사하였다. 에멀젼의 점도는 기유의 점도에 비례해서 증가하였으며 물의 배합비율에 따라 지수함수적으로 증가하였다. 에멀젼의 안정성은 에멀젼 점도와 대수함수 관계임을 보여주고 있다. 에멀젼 점도와 다른 요소와의 상관관계를 매우 복잡하며 이러한 상관관계를 해결하기 위해서는 더 많은 연구가 진행되어야 한다. 에멀젼의 점도는 에멀져의 내마모성에 거의 영향이 없으며 기유의 점도에 따라 영향을 받으며 물의 배합비가 너무 커지게 되면 마모에 심각한 나쁜 결과를 초래하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4C
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• pp.321-328
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• 2010

A Rayleigh fading channel simulator that realizes given correlation properties between two channels such as downlink/uplink is described. We propose an improved channel simulator that provides more accurate match between reference correlation and simulated one. The proposed channel simulator is based on a sum-of-sinusoids (SOS) method that handles finite sums of weighted sinusoid functions. SOS method is widely accepted in generating fading signals and obtain the exact match with the reference model if infinite number of weighted sinusoids are used. The proposed channel simulator minimizes mean-square-error (MSE) to obtain a close matched correlation properties.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.2
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• pp.101-107
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• 2009

Investigation of resaturation and thermal-hydro-mechanical behavior for the buffer of a repository requires measuring the water content of compacted bentonite. This study investigated the relative humidity of compacted bentonites using a humidity sensor (Vaisala HMT 334) applicable under high temperature and pressure, and then conducted a multi-regression analysis based on the measured results to determine relationships among the water content, relative humidity, and temperature. The relationships for the compacted bentonites with the dry densities of 1,500 $kg/m^3$ and 1,600 $kg/m^3$ were expressed as ${\omega}=0.196RH-0.029T+1.391({r^2=0.96)}$ and ${\omega}=0.199RH-0.029T+2.596({r^2=0.98)}$, respectively. These were then used to interpret the resaturation of bentonite blocks in the KENTEX test.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2002.03a
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• pp.37-44
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• 2002

터널의 초기 변형결과를 역해석에 적용하기 위하여 초기 값들과 최종변위의 상관관계를 연구하였다 Panet의 지수함수와 분수함수는 경암 터널의 내공변위 예측에 잘 맞았다. ID지점의 초기 계측변위는 선형적으로 적합시킬 수 있으나 계측 전 변형의 추정식으로는 부적합하였다. 초기 계측 결과들과 최종 변형결과는 선형적인 비례관계를 보였으며 이로써 초기 계측결과로부터 추정한 최종변형치를 이용한 역해석이 가능함을 보였다.

• 한국IT서비스학회:학술대회논문집
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• 2006.11a
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• pp.80-85
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• 2006

현재 많은 인터넷 콘텐츠 서비스가 다양한 방식의 유료 서비스로 제공되고 있지만 다양하고 복잡한 콘텐츠 서비스의 특성상 가격 책정에는 많은 어려움이 있다. 본 연구는 인터넷 영화관을 대상으로 하여 사용자들이 서비스를 선택할 때 가장 고려하는 속성을 분석하고 속성과 속성 수준을 설정한 프로파일들의 가격반응함수를 구하였다. 또한, 선형${\cdot}$곱셈${\cdot}$유인${\cdot}$구텐베르그 모델 중 가장 적합한 모델을 추정하고 독점 영역과의 관계를 살펴봄으로써 각 기업들이 서비스의 가격을 책정함에 있어서 가장 수익성 높고 적합한 전략을 설정할 수 있도록 방향을 제시하였다.