• The Korean Journal of Legal Medicine
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• v.42 no.4
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• pp.141-145
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• 2018

There have been many radiographic studies on age estimation that evaluate reduction in size of dental pulp cavity with secondary dentin formation. The Paewinsky method reported high accuracy in estimating ages by measuring the width of the pulp cavity in panoramic radiographs. The aim of this study was to evaluate the application of the Paewinsky method to digital periapical radiographs. This study was conducted on 103 cases that reported to the Section of Human Identification of the National Forensic Service. The age was calculated by applying the Paewinsky method that measures the root and pulp canal width at three points in a tooth. The estimation results were compared with those calculated by the Johanson method. When the Paewinsky models were applied to digital periapical radiographs, the errors were significantly greater as compared to the original study. The errors of the maxillary second premolar and mandibular lateral incisor were greater than those of the maxillary central incisor, lateral incisor, mandibular canine, and first premolar. Furthermore, errors of the age estimation models in level C were greater than those in levels A and B. This study could be a reference for the application of the Paewinsky method to digital periapical radiographs.

• The Korean Journal of Applied Statistics
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• v.34 no.3
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• pp.347-373
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• 2021

Over the past 50 years, explorative research on the nation's mortality decline patterns has showed a decrease in age-specific mortality rates in all age groups, but there were different improvement patterns in specific mortality rates depending on ages and periods. Greater distinct improvement was observed in mortality rates among women than men, and there was a noticeable improvement in mortality rates in certain groups especially in the more recent decades, revealing a structural change in the overall trends regarding death periods. In this paper, we compare various stochastic mortality models considering cohort effects for mortality projection using Korean female mortality data and further explore the uncertainty related to projection. It also created age-specific mortality rates and life expectancy for women until 2067 based on the results of the analysis, and compared them with future age-specific mortality rates and life expectancy provided by the national statistical office (KOISIS). The best optimal model could vary depending on data usage periods. however, considering the overall fit and predictability, the PLAT model would be regarded to have appropriate predictability in terms of the mortality rates of women in South Korea.

• Journal of the Korea Concrete Institute
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• v.14 no.3
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• pp.382-391
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• 2002

This study is devoted to the problems of thermal and shrinkage stresses in order to avoid cracking at early ages. The early-age damage induced by volume change has great influence on the long-term structural performance of the concrete structures such as its durability and serviceability To solve this complex problem, the computer programs for analysis of thermal and shrinkage stresses were developed. In these procedures, numerous material models are needed and the realistic numerical models have been developed and validated by comparison with relevant experimental results in order to solve practical problems. A framework has been established for formulation of material models and analysis with 3-D finite element method. After the analysis of the temperature, moisture and degree of hydration field in hardening concrete structure, the stress development is determined by incremental structural formulation derived from the principle of virtual work. In this study, the stress development is related to thermal and shrinkage deformation, and resulting stress relaxation due to the effect of early-age creep. From the experimental and numerical results it is found that the early-age creep p)ays important role in evaluating the accurate stress state. The developed analysis program can be efficiently utilized as a useful tool to evaluate the thermal and shrinkage stresses and to find measures for avoiding detrimental cracking of concrete structures at early ages.

• Korean Journal of Computational Design and Engineering
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• v.16 no.6
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• pp.424-436
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• 2011

In this paper, we propose a methodology of generating a parametric segment model for human body using the Korean anthropometric data. The model is defined as an articulated body model consisted with 19 ellipsoid primitives. The primitives are joined at locations representing the physical joints of human body. A lot of previous researches have suggested methodologies of generating body models using the European or American anthropometric data, so that these models were inappropriate for engineering analyses and simulations in case of the Koreans. We defined a set of 35 body dimensions representing our segment model based on the anthropometric data of Koreans. Also we defined four key parameters of age, height, weight and waist circumference, and then we applied regression equations to associate the parameters to the aforementioned dimensions. As the results, we obtained the parametric human body segment models according to the various body types and the subject-specific models for a specific individual. The models in the various industries can be used as the base models for static and dynamic analysis considering the Koreans.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.38.1-38.1
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• 2013

We present the Yonsei evolutionary population synthesis (YEPS) models based on the high-resolution empirical spectral energy distributions (SEDs). We have adopted the MILES library in the optical wavelength, and our new models based on the MILES library show good agreements with our previous models presented in the YEPS I. The effect of hot horizontal-branch (HB) stars on the integrated properties of simple stellar populations (SSPs) is again confirmed by our models based on empirical SEDs. In addition, we have extended our empirical models to the near-IR wavelength and predicted the strengths of the calcium II triplet (CaT) and the Paschen triplet (PaT) based on the INDO-US and the Cenarro library. We find that the effect of HB stars and the age of SSPs on the CaT is almost negligible. On the other hands, the PaT models are very sensitive to the existence of hot stars, e.g., HB stars and young turn-off stars, and show very similar results with Balmer lines. Interestingly, the CaT distribution of GCs in NGC 1407, which is at odds with the optical (B-I) color distribution, can be explained by the unique feature of the CaT-[Fe/H] relations that show almost the same equivalent widths in the metal-rich regime. We will also discuss the impact of the second-generation populations on the strength of the CaT.

• Journal of the korean academy of Pediatric Dentistry
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• v.8 no.1
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• pp.25-36
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• 1981

The purpose of this longitudinal study was to measure and analyze the width and length changes of dental arches at age 7 to 9. 66 children were selected for this study. Stone models obtained from these children were measured and analyzed annually. The results were as follow. 1. The widths of upper arch increased by age both in males and females except the region of second deciduous molars. 2. The widths of lower arch increased by age significantly both in males and females. 3. The lengths of dental arches increased by age both in males and females at anterior portion. ; did not increase at Posterior portion. 4. The upper widths of males were wider than those of females at age 9, but no significant difference were present at age 7 and 8. 5. The differences of the lower widths between males and females were not present except the region of the second deciduous molars (E-E) at age 7. 6. There were few differences between the lengths of males and females except the posterior lengthes at age 7. 7. The widths and lengths of upper arches were difinitely wider and longer than lower arches.

• Journal of Korean society of Dental Hygiene
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• v.11 no.5
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• pp.707-715
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• 2011

Objectives : The objective of this study was to assess a level of oral health related quality of life(OHRQoL) for rural communities elderly and to determine the association between OHRQoL and socio-economic position. Methods : The study population was elderly(60+year-old) residents of PyeongChang county, Jeongseon county, Yeongwol county, Gangwon province. A total of 171 people were invited to participate. Oral health related quality of life was measured using the GOHAI. The data were analyzed with Mann-Whitney U test or Kruskal-Wallis test and to assess socio-economic inequalities in OHRQoL(GOHAI), we used multi-variable logistic regression models. We used models adjusting for age, sex, family status factors(Model I) and compared them to models additionally adjusting for stress level(Model II). Results : There were significant differences in lower score of GOHAI at lower age group and live alone group. And we found that lower SES was significantly associated with lower score of OHRQoL. Social gradient in the score of OHRQoL persisted when adjusted for age, sex, family status, stress level. Conclusions : We recommend that oral health promotion program should be developed after due consideration SES for rural communities elderly because OHRQoL of rural communities elderly was low and association between SES and OHRQoL for rural communities elderly.

• The Journal of Advanced Prosthodontics
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• v.11 no.2
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• pp.88-94
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• 2019

PURPOSE. This study was conducted to investigate patterns of adjacent tooth displacement in the posterior implant with interproximal contact loss (ICL) by 3-D digital superimposition method. MATERIALS AND METHODS. Posterior partially edentulous patients, restored with implant fixed partial prostheses before 2011 and suffered from food impaction of ICL between 2009 and 2011, were included. Two dental casts, at the time of delivery and at the time of food impaction in a same patient, was converted into 3-D digital models through scanning and superimposition was performed to assess chronologic changes of the dentition. Directions of tooth displacement were evaluated and the amount of ICL was calculated. Correlations between the amount of ICL and elapsed time, or between the amount of ICL and age after function, were assessed at a significance level of P<.05. RESULTS. A total number of 13 patients (8 males, 5 females) with a mean age of $65.76{\pm}9.94years$ and 17 areas (4 maxillae, 13 mandibles) were included in this retrospective study. Teeth adjacent to the implant restoration showed complex displacements but characteristic tendency according to the location of the arch. The mean amount of ICL was $0.33{\pm}0.14mm$. Elapsed time from function to ICL was $61.47{\pm}31.27months$. There were no significant differences between the amount of ICL and elapsed time, or age (P>.05). CONCLUSION. Natural teeth showed various directional movements to result in occlusal change in the arch. The 3-D superimposition of chronologic digital models was a helpful method to analyze the changes of dentition and individual tooth displacement adjacent to implant restoration.

• Advances in concrete construction
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• v.13 no.1
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• pp.35-43
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• 2022

The experimental investigations into hooked-end round steel fibers (HSF) effect on the age-dependent strengths of high volume fly ash (HVFA) concrete is studied. The concrete was prepared with class F fly ash used as partial cement replacement varied from 0% to 70% on an equal weight basis. Two percentages of HSF (i.e., 0.5% and 1.5% by volume fraction) of 50 mm length were added in plain, and 50% fly ash concrete mixes. The compressive and flexural tensile strength was determined at 7, 28, 56, and 90 days. The strength results of fly ash concrete mixes with and without steel fibers were compared with the plain concrete strength. The test results indicated that the strength of fly ash concrete is comparable with the plain concrete strength and further increases with an increase in the percentage of steel fibers. The maximum flexure strength of HVFA concrete is found with 0.5% steel fibers. It is concluded that the HVFA concrete with steel fibers of 50 mm length can effectively be used in concrete construction. The analytical models are proposed to predict the age-dependent compressive and flexural tensile strength of HVFA concrete with and without HSF. The compressive and tensile strength of HVFA concrete with HSF can be predicted using these models when the 28-day compressive strength of plain concrete is known. The present study will be helpful in the design and construction of reinforced and pre-stressed concrete structures made with HVFA and HSF.

• ETRI Journal
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• v.36 no.3
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• pp.450-459
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• 2014

In this paper, we present a new, easy-to-generate system that is capable of creating virtual 3D tree models and simulating a variety of growth processes of a tree from a single, real tree image. We not only construct various tree models with the same trunk through our proposed digital image matting method and skeleton-based abstraction of branches, but we also animate the visual growth of the constructed 3D tree model through usage of the branch age information combined with a scaling factor. To control the simulation of a tree growth process, we consider tree-growing attributes, such as branching orders, branch width, tree size, and branch self-bending effect, at the same time. Other invisible branches and leaves are automatically attached to the tree by employing parametric branch libraries under the conventional procedural assumption of structure having a local self-similarity. Simulations with a real image confirm that our system makes it possible to achieve realistic tree models and growth processes with ease.