• The Korean Journal of Applied Statistics
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• v.18 no.1
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• pp.1-13
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• 2005

Latent Class model has been considered recently by many researchers and practitioners as a tool for identifying heterogeneous segments or groups in a population, and grouping objects into the segments. In this paper we consider data on prostate cancer patients from Korean National Cancer Institute and propose a method for grouping prostate cancer patients by using latent class Poisson model. A Bayesian approach equipped with a Markov chain Monte Carlo method is used to overcome the limit of classical likelihood approaches. Advantages of the proposed Bayesian method are easy estimation of parameters with their standard errors, segmentation of objects into groups, and provision of uncertainty measures for the segmentation. In addition, we provide a method to determine an appropriate number of segments for the given data so that the method automatically chooses the number of segments and partitions objects into heterogeneous segments.

• The Korean Journal of Applied Statistics
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• v.28 no.2
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• pp.325-334
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• 2015

Elderly suicide rates tend to be high in Korea. Suicide by the elderly is no longer a personal problem; consequently, further research on risk and regional factors is necessary. Disease mapping in epidemiology estimates spatial patterns for disease risk over a geographical region. In this study, we use a simultaneous conditional autoregressive model for spatial correlations between neighboring areas to estimate standard mortality ratios and mapping. The method is illustrated with cause of death data from 2006 and 2010 to analyze regional patterns of elderly suicide in Korea. By considering spatial correlations, the Bayesian spatial models, mean educational attainment and percentage of the elderly who live alone was the significant regional characteristic for elderly suicide. Gibbs sampling and grid method are used for computation.

• The Korean Journal of Applied Statistics
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• v.35 no.6
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• pp.703-724
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• 2022

Although longitudinal studies mainly produce multivariate longitudinal data, most of existing statistical models analyze univariate longitudinal data and there is a limitation to explain complex correlations properly. Therefore, this paper describes various methods of modeling the covariance matrix to explain the complex correlations. Among them, modified Cholesky decomposition, modified Cholesky block decomposition, and hypersphere decomposition are reviewed. In this paper, we review these methods and analyze Korean children and youth panel (KCYP) data are analyzed using the Bayesian method. The KCYP data are multivariate longitudinal data that have response variables: School adaptation, academic achievement, and dependence on mobile phones. Assuming that the correlation structure and the innovation standard deviation structure are different, several models are compared. For the most suitable model, all explanatory variables are significant for school adaptation, and academic achievement and only household income appears as insignificant variables when cell phone dependence is a response variable.

• The Journal of Sustainable Design and Educational Environment Research
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• v.16 no.2
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• pp.19-33
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• 2017

The purpose of this study is to derive education programs for safety training class, create unit spaces and present components and methods of utilizing the spaces for the development of facilities models closely related to various policy, operation plan and facility construction projects promoted by related institutions such as the Ministry of Education, schools, architects and companies. This study is divided into five steps. First, we reviewed the literature related basic directions for safety education and facility plan, second, field survey included both field conditions such as spatial size and facility configuration and analysis of operating conditions like hours of operation and personnel. Base on literature review and field survey, it were used to analyze strengths and weaknesses of existing safety training classes, and five facility models was developed based on the Delphi method and expert participatory design. The result show that the facility models (drafts) of safety training class were developed as follows: (1)the facility model for traffic safety(pedestrian safety, vehicle safety, subway safety) (2)the facility model for first aid(emergency rescue, how to report) (3)the facility model for disaster safety(fire evacuation safety, life earthquake safety) (4)the facility model for elevator safety(elevator safety, escalator safety) (5)the facility model for drugs and violence safety (smoking drinking, sexual harassment safety, food safety) The safety training class can be composed by combining or separating each module according to affordable space size of each school.

• Journal of Korea Port Economic Association
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• v.37 no.2
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• pp.33-53
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• 2021

This study estimated the economic value of port redevelopment projects. The port redevelopment project consists of a combination of goods between market goods and non-market goods. The value of market goods can be measured at prices in the real market, but it is difficult to convert value estimates for non-market goods into currency values. Therefore, in this study, economic benefits of port redevelopment projects were estimated by the using the CVM. The estimated model used the Hanemann's model and the Bayesian approach to estimate the WTP of the sample group's using the single boundary model. Estimating the household's WTP, the Hanemann's model was estimated at KRW 10,038.33 and the Bayesian approach at KRW 12,217.1. As of the five-year period(discount benefits), the economic benefits of the port redevelopment project were estimated at 920.7 billion won for the Hanemann's model and 1.12 trillion won for the Bayesian model on a national basis. Meanwhile, as a result of estimating economic benefits(discount benefits) based on the administrative districts of Busan·Gyeongnam·Ulsan regions(five-year period), the Hanemann's model was estimated at KRW 140.4 billion and the Bayesian approach was estimated at KRW 170.8 billion.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.87-92
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• 1999

통신사업의 경쟁체제가 활성화됨에 따라 통신정책상 상호접속정책 및 제도가 차지하는 중요성은 점점 증가하고 있다. 특히 접속료산정방식은 사업자간 이해관계가 첨예하게 대립하는 분야로서, 보다 공정하고 합리적인 방식의 도입에 대한 검토가 활발히 이루어지고 있다. 최근에는 경제적 효율성을 보다 감안한 접속료산정방식인 장기증분비용방식을 도입한다는 취지하에 장기증분비용모형에 대한 연구가 활발히 이루어지고 있다. 일본우정성은 2000년 장기증분비용방식의 도입을 목표로 금년 9월 일본의 장기중분비용모형의 최종안을 발표하였다. 본고에서는 일본의 장기증분비용모형의 구성과 내용에 대해 분석하고 있다.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.453-453
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• 2017

본 연구에서는 최근 기후변화로 인한 집중호우의 발생횟수의 경향을 확률적으로 분석함에 있어 1개월 동안 80 mm/day 이상의 강우사상을 집중호우로 정의하여, 대구 및 부산 강우관측소로부터 수집된 384개월 동안의 집중호우를 분석하였다. 집중호우 월별 발생횟수와 같은 형식의 자료의 확률적 분석은 대개 Poisson 분포 (POI)가 사용되나 자료에 포함된 0자료의 과잉은 확률분포를 왜곡시키는 문제를 발생시킨다. 본 연구에서는 이 문제를 개선하기 위하여 개발된 일반화 Poisson 확률분포 (GPD), 0-과잉 Poisson 확률분포 (ZIP), 0-과잉 일반화 Poisson 확률분포 (ZIGP), Bayesian 0-과잉 일반화 Poisson 확률분포 (Bayesian ZIGP)를 집중호우 자료에 적용하고, 5개 모형의 특성을 비교분석하였으며, Bayesian ZIGP 모형의 구축에 있어서는 정보적 사전분포를 사용함으로써 모형의 정확도를 개선하였다. 분석결과 분석하고자 하는 자료에 0이 과다하게 포함되어 있는 경우 POI 및 GPD 분포는 관측결과와는 다른 결과를 제시하여 적절한 모형으로 고려되지 못함을 알 수 있었다. 5가지 모형 중 정보적 사전분포를 탑재한 Bayesian ZIGP 모형이 가장 관측 자료와 유사한 결과를 도출하였으나 모형의 구축에 수반되는 실용적인 측면을 고려하면 ZIP 모형도 충분히 사용될 수 있는 모형으로 추천되었다.

• The Journal of the Convergence on Culture Technology
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• v.9 no.4
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• pp.1-11
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• 2023

The purpose of this study is to develop a discussion-centered teaching and learning model for nurturing creative and convergence talents. Regarding the research method, a draft model on discussion-centered teaching and learning was devised, and the model was completed through expert validation. The final draft was revised and supplemented by verifying how valid the model was when applied in class by using the derived final draft. Compared with the draft on discussion-centered teaching and learning model, the final model focused on text-reading emphasis, methods of questioning, and question generation strategies, excluding jigsaw discussions. The discussion-centered teaching and learning model developed in this study is expected to help instructors foster creative and convergence talents. Three suggestions have been provided to effectively apply this model to the field. First, an attitude of listening and respect is required during a discussion. Second, a plan should be considered on how to induce active participation of learners participating in the discussion. Third, the importance of managing discussion time was emphasized.

• Communications for Statistical Applications and Methods
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• v.1 no.1
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• pp.94-101
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• 1994

본 논문은 패널(panel) 자기회귀 모형에서 자기회귀 계수의 추정을 베이지안 방법으로 접근하였는데, 이 때 특별히 Gibbs Sampling 방법을 이용하여 사후분포를 계산하였다. 또한 모의 실험을 통하여 자기회귀계수를 Gibbs Sampling 방법으로 추정한 베이지안 추정치가 non-Bayesian 방법으로 구한 추정치보다 더 우월함을 보였다.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.2
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• pp.151-154
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• 2010

Purpose: We investigated how the movement of iris and visual axis affects the finite schematic eye Methods: Using the schematic eye with the crystalline lens in the existing forms of the radial GRIN and the spherical GRIN, the iris centre was moved 0.5 mm in nasal direction and visual axis was tilted $5^{\circ}$ in same direction, with the additional degree of 2.5 down to locate the focal point in fovea. This study analyzed performance change of the optical system, designing it same as the real eye. Results: The whole aberration distribution showed a considerable difference in performance in comparison with the real eye; the biggest difference shown at the central field of optical system. The spherical aberration showed the biggest difference, and a peripheral power error and field curvature leaned toward (+) direction in aberration distribution. Conclusions: When designing the schematic eye with the performance similar with that of the real eye by taking into consideration the iris centre and visual axis, the aberration at the center field of optical system in particular should be corrected. Spherical aberration which showed the biggest difference should be corrected in the first place. In addition, a peripheral power error and field curvature that leaned toward (+) direction should be moved toward (-) direction.