• Industrial Engineering and Management Systems
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• v.15 no.1
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• pp.110-121
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• 2016

With the growing interest in skincare and maintenance, there are increasing numbers of studies on the classification of skin type and the factors influencing each type. This study presents a novel methodology by using data mining, for the determination of the relationships between skin type, lifestyle, and patterns of cosmetic utilization. Eight skin-specific factors, which are moisture, sebum in U-zone (both cheeks), sebum in T-zone (forehead, nose, and chin), pore, melanin, wrinkle, acne, hemoglobin, were measured in 1,246 subjects living in South Korea, in conjunction with a questionnaire survey analyzing their lifestyles and pattern of cosmetic utilization. Using various multivariate statistical methods and data mining techniques, we classified the skin types based on the skin-specific values, determined the relationship between skin type and lifestyle, and accordingly sorted the subjects into clusters. Logistic regression analysis revealed gender-related differences in the skin; therefore, separate analyses were performed for males and females. Using the Gaussian Mixture Modeling (GMM) technique, we classified the subjects based on skin type (two male and four female). Using the ANOVA and decision tree techniques, we attempted to characterize the relationship between each skin type and the lifestyles of the subjects. Menstruation, eating habits, stress, and smoking were identified as the major factors affecting the skin.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.842-845
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• 2005

A method for the numerical simulation of two-dimensional free-surface flow resulting from the propagation of regular gravity waves over topography with arbitrary bottom shape is presented. The method is based on the numerical solution of the Euler equations subject to the fully nonlinear free-surface boundary conditions and the appropriate bottom, inflow and outflow conditions using a hybrid finite-differences and spectral-method scheme. The formulation includes a boundary-fitted transformation, and is suitable for extension to incorporate large-eddy simulation (LES) and large-wave simulation (LWS) terms for turbulence and breaking wave modeling, respectively. Results are presented for the simulation of the free-surface flow over two different bottom topographies, with constant slope values of 1:10 and 1:20, two different inflow wave lengths and two different inflow wave heights. An absorption outflow zone is utilized and the results indicate minimum wave reflection from the outflow boundary. Over the bottom slope, lengths of waves in the linear regime are modified according to linear theory dispersion, while wave heights remain more or less unchanged. For waves in the nonlinear regime, wave lengths are becoming shorter, while the free surface elevation deviates from its initial sinusoidal shape.

• Steel and Composite Structures
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• v.17 no.4
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• pp.471-495
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• 2014

The responses of steel buildings with perimeter moment resisting frames (PMRF) with medium size columns (W14) are estimated and compared with those of buildings with deep columns (W27), which are selected according to two criteria: equivalent resistance and equivalent weight. It is shown that buildings with W27 columns have no problems of lateral torsional, local or shear buckling in panel zone. Whether the response is larger for W14 or W27 columns, depends on the level of deformation, the response parameter and the structural modeling under consideration. Modeling buildings as two-dimensional structures result in an overestimation of the response. For multiple response parameters, the W14 columns produce larger responses for elastic behavior. The axial load on columns may be significantly larger for the buildings with W14 columns. The interstory displacements are always larger for W14 columns, particularly for equivalent weight and plane models, implying that using deep columns helps to reduce interstory displacements. This is particularly important for tall buildings where the design is usually controlled by the drift limit state. The interstory shears in interior gravity frames (GF) are significantly reduced when deep columns are used. This helps to counteract the no conservative effect that results in design practice, when lateral seismic loads are not considered in GF of steel buildings with PMRF. Thus, the behavior of steel buildings with deep columns, in general, may be superior to that of buildings with medium columns, using less weight and representing, therefore, a lower cost.

• Journal of Welding and Joining
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• v.11 no.3
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• pp.34-47
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• 1993

Finite element models were developed for thermal and residual stress analysis for the specific welding problems. They were used to evaluate the effectiveness of the various welding heat input models, such as ramp heat input function and lumped pass models. Through the parametric studies, thermal-mechanical modeling sensitivity to the ramp function and lumping techniques was determined by comparing the predicted results with experimental data. The kinetics for residual stress formation during welding can be developed by iteration of various proposed mechanisms in the parametric study. A ramp heat input function was developed to gradually apply the heat flux with variable amplitude to the model. This model was used to avoid numerical convergence problems due to an instantaneous increase in temperature near the fusion zone. Additionally, it enables the model to include the effect of a moving arc in a two-dimensional plane. The ramp function takes into account the variation in the out of plane energy flow in a 2-D model as the arc approaches, travels across, and departs from each plane under investigation. A lumped pass model was developed to reduce the computation cost in the analysis of multipass welds. Several weld passes were assumed as one lumped pass in this model. Recommendations were provided about ramp lumping techniques and the optimum number of weld passes that can be combined into a single thermal input.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.2
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• pp.104-112
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• 1994

The scavenging efficiency has a great influence on the performance of a diesel engine, especially slow two-stroke diesel engines which are usually used as a marine propulsion power plant. And this is greatly affected by the conditions in the cylinder, scavenging manifold and exhaust manifold during the gas exchange process. There are many factors to affect on the scavenging efficiency and these factors interact each other very complicatedly. Therefore the simulation program of the gas exchange process is very useful to improve and predict the scavenging efficiency, due to the high costs associated with redesign and testing. In this paper, a three-zone scavenging model for two-stroke uniflow engines was developed to link a control-volume-type engine simulation program for performance prediction of long-stroke marine engines. In this model it was attempted to simulate the three different regions perceived to exist inside the cylinder during scavenging, namely the air, mixing and combystion products regions, by modeling each region as a seperate control volume. Finally the scavenging efficiency was compared with three type of scavenging modes, that is, pure displacement, partial mixing and prefect mixing.

• Computers and Concrete
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• v.31 no.2
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• pp.151-161
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• 2023

This paper presents an investigation of variables that cause spurious cracking in numerical modeling of concrete fracture. Spurious cracks appear due to the approximate nature of numerical modeling. They overestimate the dissipated energy, leading to divergent results with mesh refinement. This paper is limited to quasi-static loading regime, homogeneous models, cracking as the only nonlinear mode of deformation and cracking only due to tensile loading. Under these conditions, some variables that can be related to spurious cracking are: mesh alignment, ductility, crack band width, structure size, mesh refinement and load increment size. Case studies illustrate the effect of each variable and convergence analyses demonstrate that, after all, load-increment size is the most important variable. Theoretically, a sufficiently small load increment is able to eliminate or at least alleviate the detrimental influence of the other variables. Such load-increment size might be prohibitively small, rendering the simulation unfeasible. Hence, this paper proposes two alternatives. First, it is proposed an algorithm that automatically find such small load increment size automatically, which not necessarily avoid large computations. Then, it is proposed a double simulation technique, in which the crack is forced to propagate through the localization zone.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.4
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• pp.287-294
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• 2012

Sedimentary environment in coastal zone has been changing due to a large number of coastal structures and continuous coastal development. As a result, the environment has been changing. In particular, the economic and environmental damage can occur due to cohesive sediment transport closely related with the fate of pollutants. Due to large sea wall construction the ebb dominance in the Mokpo coastal waters has been clearer. Cohesive sediment transport was simulated by the EFDC model. The simulated SS showed good agreements with the observed SS. From the sensitivity analysis of sediment parameters, we found out that the erosion rate, the critical shear stresses for erosion and deposition, and the settling velocity are important factors in cohesive sediment transport modeling.

• Journal of Soil and Groundwater Environment
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• v.9 no.4
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• pp.32-41
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• 2004

Analysis of water-level fluctuation due to goundwater-surface water interaction in coastal aquifers is carried out by numerical modeling. The conceptual model used in this study has a stream boundary and a tidal boundary that forms a right angle and the stream partially penetrates the aquifer. We analyzed the effect of each boundary and the simultaneous effect of the two boundary conditions. The area of influence caused by the stream boundary increased during the simulation, while the influence zone of the coastal boundary was relatively constant. The groundwater level near the zone where two boundaries meet may rise by the action of combined effect of the two boundaries or may not change by cancelling the effect of each boundary. Thereafter, care must be taken when hydraulic parameters are estimated using sinusoidal oscillations of hydraulic head in coastal aquifers. Sensitivity analysis is employed to develop insight into the controls on groundwater level fluctuations. In this study our analyses focused on the effect of conductance and the stream width to the aquifer nearby.

• Journal of Korean Society of Transportation
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• v.34 no.6
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• pp.489-498
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• 2016

The objective of this study is to develop road traffic accident model involving child pedestrian especially at school zones and its surrounding area. The analysis is based upon traffic accident data collected near sixty elementary schools in City of Cheongju during 2012 and 2014. This study results in two statistical models ; one is to predict the number of road traffic accidents involving children, and the other is to predict EPDO(Equivalent Prperty Damage Only). These models are represented as Poisson models. which are statistically significant with the likelihood ratios of 0.533 and 0.273. The common explanatory variables of these models are the ratio of road section with more than 4 lanes, the number of entrance and exit, the number of signalized crosswalk in school zone, the number of school zone signage including road surface marking, and the number of speed limit signs. The specific variables are the length of road stretch in school zone, the number of reflector mirrors, and the number of signalized crosswalk outside school zone. It is concluded that these types of road safety facilities can reduce the number of traffic accidents involving children at school zones and its surrounding area.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.221-226
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• 2004

For comparing more than two images, the precise geometric corrections should be preceded because it necessary to eliminate systematic errors due to basic sensor information difference and non-systematic errors due to topographical undulations. In this study, we did sensor modeling using satellite sensor information to make a basic map of change detection for artificial topography. We eliminated the systematic errors which can be occurred in photographing conditions using GCP and DEM data. The Kompsat EOC images relief could be reduced by precise rectification method. Classifying images which was used for change detections by city and forest zone, the accuracy of the matching results are increased by 10% and the positioning accuracies also increased.