• 한국환경과학회:학술대회논문집
• /
• 한국환경과학회 2003년도 International Symposium on Clean Environment
• /
• pp.37-42
• /
• 2003

We have analyzed the characteristics of the sea surface winds and wind waves near the Korean marginal seas on the basis of prediction results of the sea surface winds from MM5/KMA model, which is being used for the operation system at the Korea Meteorological observation buoy data to verify the model results during Typhoon events. The correlation coefficients between the models and observation data reach up to about 95％, supporting that these models satisfactorily simulate the sea surface winds and wave heights even at the coastal regions. Based on these verification results, we have carried out numerical experiments about the wave modulation. When there exist an opposite strong current for the propagation direction of the waves or wind direction, wave height and length gets higher and shorter, and vice versa. It is proved that these modulations of wave parameters are well generated when wind speed is relatively week.

• Communications for Statistical Applications and Methods
• /
• 제27권6호
• /
• pp.675-688
• /
• 2020

In survival analysis of observational data, the inverse probability weighting method and the Cox proportional hazards model are widely used when estimating the causal effects of multiple-valued treatment. In this paper, the two kinds of weights have been examined in the inverse probability weighting method. We explain the reason why the stabilized weight is more appropriate when an inverse probability weighting method using the generalized propensity score is applied. We also emphasize that a marginal hazard ratio and the conditional hazard ratio should be distinguished when defining the hazard ratio as a treatment effect under the Cox proportional hazards model. A simulation study based on real data is conducted to provide concrete numerical evidence.

• Communications for Statistical Applications and Methods
• /
• 제15권6호
• /
• pp.969-976
• /
• 2008

Mixed linear models have been widely used in various correlated data including multivariate survival data. In this paper we extend hierarchical-likelihood(h-likelihood) approach for mixed linear models with right censored data to that for left censored data. We also allow a general random-effect structure and propose the estimation procedure. The proposed method is illustrated using a numerical data set and is also compared with marginal likelihood method.

• 한국경영과학회지
• /
• 제24권2호
• /
• pp.109-119
• /
• 1999

The average shadow price is a substitute for the traditional marginal shadow price. It can serve as a standard for decision making problems about the economic resources where the marginal analysis gives no useful information. This paper treats the average shadow price in pure integer programming and shows some stability properties of it. This implies that the values of the average shadow prices once computed are reliable within some extent of the data perturbations of the integer programming model.

• International Journal of Reliability and Applications
• /
• 제10권2호
• /
• pp.63-79
• /
• 2009

A new bivariate linear failure rate distribution is introduced through a shock model. It is proved that the marginal distributions of this new bivariate distribution are linear failure rate distributions. The joint moment generating function of the bivariate distribution is derived. Mixtures of bivariate linear failure rate distributions are also discussed. Application to a real data is given.

• 대기
• /
• 제16권4호
• /
• pp.279-301
• /
• 2006

This study analyzed the characteristics of the wind waves near the Korean marginal seas in the 2002 - 2005 year using the third generation wave model, WAVEWATCH - III model. In order to investigate the model performance, model results were compared with the marine meteorological observation results. The 4 years average correlation coefficient between model and observation shows very high value of about 0.77. The model of this study represents very well the characteristics of wind waves near the Korean marginal seas. Simulated monthly sea surface winds and wind waves show the evident spatial variations and this model also simulates very well seasonal characteristics of wind waves in this region.

• The Journal of Advanced Prosthodontics
• /
• 제10권3호
• /
• pp.236-244
• /
• 2018

PURPOSE. To determine the discrepancy in monolithic zirconium dioxide crowns made with computer-aided design and computer-aided manufacturing (CAD/CAM) systems by comparing scans of silicone impressions and of master casts. MATERIALS AND METHODS. From a Cr-Co master die of a first upper left molar, 30 silicone impressions were taken. The 30 silicone impressions were scanned with the laboratory scanner, thus obtaining 30 milled monolithic yttrium stabilized zirconium dioxide (YSZD) crowns (the silicone group). They were poured and the working models were scanned, obtaining 30 milled monolithic yttrium stabilized zirconium dioxide (YSZD) crowns (the plaster group). Three predetermined points were analyzed in each side of the crown (Mesial, Distal, Vestibular and Palatal), and the marginal fit was evaluated with SEM (${\times}600$). The response variable is the discrepancy from the master model. A repeated measures ANOVA with two within subject factors was performed to study significance of main factors and interaction. RESULTS. Mean marginal discrepancy was $22.42{\pm}35.65{\mu}m$ in the silicone group and $8.94{\pm}14.69{\mu}m$ in the plaster group. The statistical analysis showed significant differences between the two groups and also among the four aspects. Interaction was also significant (P=.02). CONCLUSION. The mean marginal fit values of the two groups were within the clinically acceptable values. Significant differences were found between the groups according to the aspects studied. Various factors influenced the accuracy of digitizing, such as the design, the geometry, and the preparation guidance, as well as the texture, roughness and the color of the scanned material.

• 한국산림과학회지
• /
• 제98권3호
• /
• pp.297-304
• /
• 2009

본 연구는 국립공원 입장료 폐지 후 탐방수요가 급증한 북한산국립공원의 사회 심리적 수용력을 평가하고 생태적 수용력 관리를 위한 단계별 관리전략 마련을 위해 수행되었다. 현지 설문조사는 2008년 10월 북한산국립공원 탐방객 512명을 대상으로 이루어졌다. 한계효용이론 모델을 이용하여 분석한 결과 북한산국립공원의 1일 사회 심리적 수용력은 약 65,000명으로 추정되었다.

• 대한치과기공학회지
• /
• 제36권3호
• /
• pp.159-164
• /
• 2014

Purpose: The purpose of this study was analysis of quality of fixed prostheses fabricated by dental CAD/CAM system. Methods: The ten same cases of stone models were manufactured by dental scannable model, and stone models were scanned using the dental scanner for changing digital model. Ten digital models were completed. The design of zirconia core for zirconia based all-ceramic crown was conducted by the dental CAD program. The samples were fabricated using the pre-sintered zirconia block by dental milling machine. Marginal gaps were analyzed using by silicone replica technique at the eight parts for quality analysis of samples. One-way ANOVA was used for statistical analysis(${\alpha}=0.05$). Results: The mean for marginal gaps were $93.2{\sim}99.1{\mu}m$ at the eight parts. One-was ANOVA didn't show significant differences(p=0.089). Conclusion: The fixed dental prostheses fabricated by dental CAD/CAM were within clinically acceptable range.

• Journal of the Korean Data and Information Science Society
• /
• 제24권3호
• /
• pp.651-658
• /
• 2013

For the marginal model and generalized estimating equations (GEE) method there is important full covariates conditional mean (FCCM) assumption which is pointed out by Pepe and Anderson (1994). With longitudinal data with time-varying stochastic covariates, this assumption may not necessarily hold. If this assumption is violated, the biased estimates of regression coefficients may result. But if a diagonal working correlation matrix is used, irrespective of whether the assumption is violated, the resulting estimates are (nearly) unbiased (Pan et al., 2000).The quadratic inference functions (QIF) method proposed by Qu et al. (2000) is the method based on generalized method of moment (GMM) using GEE. The QIF yields a substantial improvement in efficiency for the estimator of ${\beta}$ when the working correlation is misspecified, and equal efficiency to the GEE when the working correlation is correct (Qu et al., 2000).In this paper, we interest in whether the QIF can improve the results of the GEE method in the case of FCCM is violated. We show that the QIF with exchangeable and AR(1) working correlation matrix cannot be consistent and asymptotically normal in this case. Also it may not be efficient than GEE with independence working correlation. Our simulation studies verify the result.