• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.3A
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• pp.199-207
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• 2009

In this paper, new vehicular load model is developed for reliability-based bridge design code. Rational load model and statistical properties of loads are important for developing reliability-based design code. In the previous paper, truck weight data collected at eight locations using WIM or BWIM system are analyzed to calculate the maximum truck weights for specified bridge lifetime. Probability distributions of upper 20% total truck weight are assumed as Extreme Type I (Gumbel Distribution) and 100 years maximum weights are estimated by linear regression. In this study, effects of multiple presence of trucks are analyzed. Probability of multiple presence of trucks are estimated and corresponding multiple truck weights are calculated using the same probability distribution function as in the previous paper. New vehicular live load model are proposed for span length from 10 m to 200 m. New model is compared with current Korean model and various load models of other countries.

• The Korean Journal of Applied Statistics
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• v.33 no.2
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• pp.123-136
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• 2020

It is common to encounter correlated multiple outcomes measured on the same subject in various research fields. In developmental toxicity studies, presence of malformed pups and fetal weight are measured on the pregnant dams exposed to different levels of a toxic substance. Joint analysis of such two outcomes can result in more efficient inferences than separate models for each outcome. Most methods for joint modeling assume a normal distribution as random effects. However, in developmental toxicity studies, the response distributions may change irregularly in location and shape as the level of toxic substance changes, which may not be captured by a normal random effects model. Motivated by applications in developmental toxicity studies, we propose a Bayesian joint model for binary and continuous outcomes. In our model, we incorporate a skewed logit model for the binary outcome to allow the response distributions to have flexibly in both symmetric and asymmetric shapes on the toxic levels. We apply our proposed method to data from a developmental toxicity study of diethylhexyl phthalate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.43-49
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• 2015

In recent years, the amount of heat generated inside of the computer has more increased because of high performance, multi-function, miniaturization and light weight. It is necessary to control the effective heat generation to improve performance and life extension of the computer. In this study, thermoelectric cooling system was manufactured using thermoelectric module and was attached to computer in order to control the heat generated inside computer. And the temperature distributions inside computer were experimentally measured and compared with and without thermoelectric cooling system to investigate the effect of cooling system. Also, to estimate the new cooling system which can substitute for the existing computer cooling system, temperature distributions inside computer were calculated by numerical analysis when there was no cooling system and was applied only cooling system to computer.

• The Korean Journal of Applied Statistics
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• v.27 no.3
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• pp.501-512
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• 2014

Modified cut-off sampling is widely used for highly skewed data. A serious drawback of modified cut-off sampling is the difficulty of adjustment of non-response in take-all stratum. Therefore, solutions of the problems of non-response in take-all stratum have been studied in various ways such as substitute of samples, imputation or re-weight method. In this paper, a new cut-off point based on minimizing MSE being used in exponential and power functions is suggested and it can be reduced the number of take-all stratum. We also investigate another cut-off point determination method with underlying distributions such as truncated log-normal and truncated gamma distributions. Finally we suggest the optimal cut-off point which has a minimum of take-all stratum size among suggested methods. Simulation studies are performed and Labor Survey data and simulated data are used for the case study.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.6 no.1
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• pp.25-33
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• 1986

Natural river channels usually have a deep section and one or two floodplains, which is called a compound channel. As the general method in the compound channel overestimates the discharge capacity, the momentum transfer due to interaction between the main channel flow and flow over its floodplain must be considered. Scale model experiments are performed for the rectangular main channel with an asymmetrical floodplain. Firstly, velocities are measured at various section grids. Secondary, boundary shear stresses are calculated from velocity distributions. Lastly, in order to determine the apparent shear force, the shear stress distributions are integrated along the wetted perimeter for the full cross-section and equated to the total weight force in the flow direction. The hydraulic characteristics in a compound channel are closely examined with the scales of length, velocity, boundary shear stress, and apparent shear force which are described with the various relationships.

• Korean Journal of Food Science and Technology
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• v.27 no.4
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• pp.631-634
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• 1995

Some structural characteristics of hot-water insoluble rice starch [3 varieties of Japonica type and 3 varieties of Tongil type(Japonica-Indica breeding type)]were investigated. The amylose contents of hot-water insoluble starches were 2.7-6.1%. The chain distributions of hot-water insoluble starches were composed of super long chain of above ${\overline{DP}}\;55$ (31.9-38.7%), B chain of ${\overline{DP}}\;40-50$ (12.3-18.0%) and A chain of ${\overline{DP}}\;10-20$ (48.5-50.4%). The chain distributions of hot-water insoluble starches and their ${\beta}-limit$ dextrin were difference between rice varieties and their were differ from those of amylopectin and their ${\beta}-limit$ dextrin. these result suggest that hot-water insolubility of rice starch was showed its characteristic on the varieties and it be responsible for the molecular structure of amylopectin.

• Journal of Korean Public Health Nursing
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• v.33 no.3
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• pp.364-378
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• 2019

Purpose: This study examined the distribution of the body mass index (BMI) according to gender and age among Korean children and adolescents to compare the distributions of being underweight, normal, overweight, and obese using both Korean and international criteria. Methods: This secondary data analysis utilized the data of the 2016 Korean National Health Examination for School Students Height, weight, and BMI distributions among children and adolescents were analyzed using descriptive statistics, and the differences in BMI distribution according to gender and age were analyzed using chi-square tests. Differences in the mean BMI according to the Korean Centers for Disease Control (KCDC), the World Health Organization (WHO), and the International Obesity Task Force (IOTF) criteria were analyzed using ANOVA. Results: Using the IOTF criteria, the prevalence of underweight, overweight, and obesity among grades 1-12 students was 6.7%, 20.8%, and 7.1%, respectively; 1.6%, 21.3%, and 11.8%, respectively, according to the WHO criteria; and 5.8%, 10.1%, and 13.0%, respectively, according to the KCDC criteria. Conclusion: It is recommended to use the IOTF criteria for health promotion programs to target underweight children and adolescents while the WHO and KCDC criteria should be used for health programs for treating obese people.

• International Journal of Highway Engineering
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• v.11 no.1
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• pp.47-58
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• 2009

Calibrating toll roads of highway networks needs additional weights within volume delay functions not like other general highway lints. However, current methods assigning additional weights in the volume delay function of toll roads are not sufficiently enough to predict real toll road volumes measured, since it does not consider discounting rates and an extra charges. This study develops methods to improve relevant and reliable volume delay functions. Suggested ideas include a method of weighting volume delay functions considering a value of time of vehicle types, a method of weighting volume delay functions considering lane distributions of vehicles, and a method of weighting volume delay functions considering percentages of link lengths per a number of lanes of toll roads. It is found that the method of weighting volume delay functions considering lane distributions of vehicles show most reliable and appropriate results, while the first method shows overestimation and the third method does underestimation of highway link volumes. In terms of assignment methods, total OD equilibrium assignment shows better results than PCU based assignment.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.723-736
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• 1992

Most degeneating diseases and back pains in the orthopaedic disease are originated from the unbalance of stress distribution in the low-lumbar spine. Therefore the stress analysis of lowerback is indispensible to the clinical diagnosis for the developing reason and the developing process of diseases. Therefore the same model materials as following are eveloped to analyze the stress distributions of lower-back by photoelastic experiment. The verterbral body and the process are molded from epoxy resin(the weight ratio of Araldite and hardner is 10 to 3), models are geometrically identical to them in vivo respectively and the ratio of their elastic modulus to that of model material is 1 to 10. It is assured that KE-1300 Silicon(E=0.8MPa), TSE-3562 Silicon(0.5MPa) and the composite silicon(3MPa) (the weight ratio of KE-1300 silicon and Jioreal : 10 to 4) are respectively effective as the model materials of ligament, musles and intervertevral disc which is essential to the movement of low-lumbar spine. All the elements associated with the movement of the low-lumbar spine are molded through the molding method developed in this research and assembled with the angles between the verterbra and the disc in the normal human lumbosacral spine. The stress distributions of the assembled model are analyzed by photoelastic experiment. It is certified by comparing the results of photoelastic experimebt with the clinical situations that the loading dveice and the loading conceptions used in this paper are effective.

• Journal of Korea Water Resources Association
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• v.52 no.7
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• pp.493-503
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• 2019

This study presents a new method of estimating the size distribution of river bed gravel through image processing. The analysis was done in two steps; first the individual grain images were analyzed and then the grain particle segmentation of river-bed images were processed. In the first part of the analysis, the relationships (long axes, intermediate axes and projective areas) between grain features from images and those measured were compared. For this analysis, 240 gravel particles were collected at three river stations. All particles were measured with vernier calipers and weighed with scales. The measured data showed that river gravel had shape factors of 0.514~0.585. It was found that the weight of gravel had a stronger correlation with the projective areas than the long or intermediate axes. Using these results, we were able to establish an area-weight formula. In the second step, we calculated the projective areas of the river-bed gravels by detecting their edge lines using the ImageJ program. The projective areas of the gravels were converted to the grain-size distribution using the formula previously established. The proposed method was applied to 3 small- and medium- sized rivers in Korea. Comparisons of the analyzed size distributions with those measured showed that the proposed method could estimate the median diameter within a fair error range. However, the estimated distributions showed a slight deviation from the observed value, which is something that needs improvement in the future.