• The Korean Journal of Applied Statistics
• /
• v.29 no.5
• /
• pp.773-786
• /
• 2016

Multiple quantile regression that simultaneously estimate several conditional quantiles of response given covariates can provide a comprehensive information about the relationship between the response and covariates. Some quantile estimates can cross if conditional quantiles are separately estimated; however, this violates the definition of the quantile. To tackle this issue, multiple quantile regression with non-crossing constraints have been developed. In this paper, we carry out a comparison study on several popular methods for non-crossing multiple linear quantile regression to provide practical guidance on its application.

• Journal of the Korean Society for Railway
• /
• v.9 no.2 s.33
• /
• pp.169-173
• /
• 2006

The major objective of this study is to investigate the fatigue life evaluation of immovability crossing for railway turnout by the field test. In railway engineering, an appliance is necessary to allow a vehicle to move from one track to another. This appliance came to be known technically as turnout. So, turnout is required very complex railway technologies such as rolling stock, track. Due to the plan under the application of high speed train, turnout are needed more stable far fatigue behaviors. It analyzed the mechanical behaviors of turnout crossing with propose its advanced technical type on the field test and fatigue evaluation far the dynamic fatigue characteristics. As a result, the advanced type crossing are obviously effective for the fatigue damage ratio and dynamic response which is non-modified type. The analytical and experimental study are carried out to investigate the passing path of contact surface and fatigue damage trend decrease dynamic stresses and deflections on advanced crossing type, And the advanced type reduce dynamic fatigue damage ratio and increase fatigue life(about each 38%) more than non-modified type. From the field test results of the servicing turnout crossing, it is evaluated that the modification of contact angle, weight, material and sectional properties is very effective fur ensure against fatigue risks.

• Proceedings of the KSR Conference
• /
• 2006.11b
• /
• pp.447-453
• /
• 2006

The major objective of this study is to investigate the fatigue behavior evaluation of immovability crossing for railway turnout by the field test. In railway engineering, an appliance is necessary to allow a vehicle to move from one track to another. This appliance came to be known technically as turnout. So, turnout is required very complex railway technologies such as rolling stock, track. Due to the plan under the application of high speed train, turnout are needed more stable for fatigue behaviors. It analyzed the mechanical behaviors of turnout crossing with propose its advanced technical type on the field test and fatigue evaluation for the dynamic fatigue characteristics. As a result, the advanced type crossing are obviously effective for the fatigue damage ratio and dynamic response which is non-modified type. The analytical and experimental study are carried out to investigate the passing path of contact surface and fatigue damage trend decrease dynamic stresses and deflections on advanced crossing type. And the advanced type reduce dynamic fatigue damage ratio and increase fatigue life(about each 38%)more than non-modified type. From the field test results of the servicing turnout crossing, it is evaluated that the modification of contact angle, weight, material and sectional properties is very effective for ensure against fatigue risks.

• The Korean Journal of Applied Statistics
• /
• v.26 no.6
• /
• pp.915-922
• /
• 2013

Quantile regression can estimate multiple conditional quantile functions of the response, and as a result, it provide comprehensive information of the relationship between the response and the predictors. However, when estimating several conditional quantile functions separately, two or more estimated quantile functions may cross or overlap and consequently violate the basic properties of quantiles. In this paper, we propose a new stepwise method to estimate multiple non-crossing quantile functions using constraints on the kernel coefficients. A simulation study are presented to demonstrate satisfactory performance of the proposed method.

• The Korean Journal of Applied Statistics
• /
• v.33 no.6
• /
• pp.753-762
• /
• 2020

With an increasing interest in integrating artificial intelligence (AI) into interview processes, the Republic of Korea (ROK) army is trying to lead and analyze AI-powered interview platform. This study is to analyze the AI interview data using a unified non-crossing multiple quantile tree (UNQRT) model. Compared to the UNQRT, the existing models, such as quantile regression and quantile regression tree model (QRT), are inadequate for the analysis of AI interview data. Specially, the linearity assumption of the quantile regression is overly strong for the aforementioned application. While the QRT model seems to be applicable by relaxing the linearity assumption, it suffers from crossing problems among estimated quantile functions and leads to an uninterpretable model. The UNQRT circumvents the crossing problem of quantile functions by simultaneously estimating multiple quantile functions with a non-crossing constraint and is robust from extreme quantiles. Furthermore, the single tree construction from the UNQRT leads to an interpretable model compared to the QRT model. In this study, by using the UNQRT, we explored the relationship between the results of the Army AI interview system and the existing personnel data to derive meaningful results.

• Journal of the Society of Naval Architects of Korea
• /
• v.29 no.2
• /
• pp.60-65
• /
• 1992

The roll response of a ship to random beam seas is investigated in terms of the threshold crossing process. The non-white excitation process is modeled as an equivalent white-noise one based on the assumption that the upcrossing properties of the response can be approximately replaced by the excitation with a white noise process with a suitable intensity. Then the non-linear damping is reinstated. The reinstated equation of motion with the equivalent white-noise intensity is solved using the equivalent non-linear method to get the desired probability density function. The proposed scheme is tested extensively with varing coefficients.

• Journal of Auto-vehicle Safety Association
• /
• v.16 no.2
• /
• pp.6-13
• /
• 2024

This paper presents a method of longitudinal motion planning of autonomous vehicles to deal with the non-signalized crosswalk environment. Based on the traffic laws, vehicles should slow down when passing the non-signalized crosswalk to prepare for situations where a nearby pedestrian starts to cross. If a pedestrian is in the crossing phase, vehicles should stop in front of the stop-line and wait until the pedestrian finishes the crossing maneuver. To realize these behaviors in autonomous vehicles, the driving mode and corresponding driving strategy are determined when vehicles encounter the crosswalk. The driving mode is determined according to the behavioral status of the nearby pedestrian. Longitudinal motion for the stopping or passing maneuver is planned according to the determined driving mode. The proposed algorithm has been validated via autonomous driving tests with our test vehicle in a real world. The test results show that the proposed algorithm enables the test vehicle to follow the traffic laws and behave safely against crossing pedestrians in the non-signalized crosswalk.

• Journal of information and communication convergence engineering
• /
• v.6 no.2
• /
• pp.146-149
• /
• 2008

Simulation and signal conditioning on the time domain surface elevation records are conducted to verify the proposed Welch's method in non-directional ocean wave spectrum analysis. These spectrum data are further conditioned to provide wave characteristic that better describe the sea states. Comparison of significant wave height and zero crossing period between the proposed method and a reference toolkit are presented.

• Journal of the Korean Data and Information Science Society
• /
• v.21 no.6
• /
• pp.1319-1325
• /
• 2010

Quantile regression provides a more complete statistical analysis of the stochastic relationships among random variables. Sometimes quantile functions estimated at different orders can cross each other. We propose a new non-crossing quantile regression method applying support vector median regression to restricted regression quantile, restricted support vector quantile regression. The proposed method provides a satisfying solution to estimating non-crossing quantile functions when multiple quantiles for high dimensional data are needed. We also present the model selection method that employs cross validation techniques for choosing the parameters which aect the performance of the proposed method. One real example and a simulated example are provided to show the usefulness of the proposed method.

• Geomechanics and Engineering
• /
• v.34 no.4
• /
• pp.409-424
• /
• 2023

Response of the pipeline crossing fault is considered as the large strain problem. Proper estimation of the pipeline response plays important role in mitigation studies. In this study, an advanced continuum modeling including material non-linearity in large strain deformations, hardening/softening soil behavior and soil-pipeline interaction is applied. Through the application of a fully nonlinear analysis based on an explicit finite difference method, the mechanics of the pipeline behavior and its interaction with soil under large strains is presented in more detail. To make the results useful in oil and gas engineering works, a continuous pipeline of two steel grades buried in two clayey soil types with four different crossing angles of 30°, 45°, 70° and 90° with respect to the pipeline axis have been considered. The results are presented as the fault movement corresponding to different damage limit states. It was seen that the maximum affected pipeline length is about 20 meters for the studied conditions. Also, the affected length around the fault cutting plane is asymmetric with about 35% and 65% at the fault moving and stationary block, respectively. Local buckling is the dominant damage state for greater crossing angle of 90° with the fault displacement varying from 0.4 m to 0.55 m. While the tensile strain limit is the main damage state at the crossing angles of 70° and 45°, the cross-sectional flattening limit becomes the main damage state at the smaller 30° crossing angles. Compared to the stiff clayey soil, the fault movement resulting 3% tensile strain limit reach up to 40% in soft clayey soil. Also, it was seen that the effect of the pipeline internal pressure reaches up to about 40% compared to non-pressurized condition for some cases.