• Smart Structures and Systems
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• v.29 no.1
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• pp.41-51
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• 2022

Cables are critical components of cable-stayed bridges. A structural health monitoring system provides real-time cable tension recording for cable health monitoring. However, the measurement data involve multiple sources of variability, i.e., varying environmental and operational factors, which increase the complexity of cable condition monitoring. In this study, a one-class classification method is developed for cable condition assessment using Bayesian factor analysis (FA). The single-peaked vehicle-induced cable tension is assumed to be relevant to vehicle positions and weights. The Bayesian FA is adopted to establish the correlation model between cable tensions and vehicles. Vehicle weights are assumed to be latent variables and the influences of different transverse positions are quantified by coefficient parameters. The Bayesian theorem is employed to estimate the parameters and variables automatically, and the damage index is defined on the basis of the well-trained model. The proposed method is applied to one cable-stayed bridge for cable damage detection. Significant deviations of the damage indices of Cable SJS11 were observed, indicating a damaged condition in 2011. This study develops a novel method to evaluate the health condition of individual cable using the FA in the Bayesian framework. Only vehicle-induced cable tensions are used and there is no need to monitor the vehicles. The entire process, including the data pre-processing, model training and damage index calculation of one cable, takes only 35 s, which is highly efficient.

• Journal of Korean Institute of Industrial Engineers
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• v.41 no.4
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• pp.352-358
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• 2015

It is important to guarantee the safety of vehicle to minimize the damage to the driver in case of the accidents. In order to inspect and later enhance the safety of vehicle, the owner of the vehicle usually have a vehicle safety inspection. The Korea Transportation Safety Authority (KOTSA) issues the Comprehensive Performance Inspection Certificate after vehicle inspection. The certificate only specify the legal inspection criteria for safety and measured values of the safety parameters, however, as ordinary driver in lack of expert knowledge about the vehicle is difficult to understand the contents of the Certificate. Thus, in this paper, the authors try to give the information about the inspection results in easier way to understand. This information not only guarantees the owner of the vehicle to better understand the inspection results, but it also gives the opportunity to the driver to deal with the specific problem listed in the results. The methods in this paper are to transform the vehicle inspection data into the non parametric distribution to easily represent the values to the index later on. Also, example indexes are presented to the actually inspected vehicle based on the reference distribution to show the better assessment of the developed method.

• Journal of Environmental Science International
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• v.28 no.12
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• pp.1133-1145
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• 2019

Successful launch requires state-of-the-art launch vehicle technology and constant test operations, However, the meteorological threat to the launch vehicle flight trajectory is also an important factor for launch success. Atmospheric stability above the Naro Space Center at the this time is very important, especially because the initial flight operation can determine the success of the launch. Moreover, during the flight of launch vehicle with rapid pressure and thrust into the atmosphere, convection activity in the atmosphere may create environmental conditions that cause severe weather threats such as thunderstorms. Hence, studies of atmospheric instability characteristics over the Naro Space Center are a necessary part of successful launch missions. Therefore, the main aims of this study were to (1) verify the atmospheric stability index and convection activity characteristics over the Naro Space Center using radiosonde data observed from 2007 to 2018 by the Naro Space Center, (2) analyze changes in the atmospheric stability index according to monthly and seasonal changes, and (3) assess how the calculated atmospheric stability index is related to actual thunderstorm occurrence using statistical analysis. Additionally, we aimed to investigate the atmospheric characteristics above the Naro Space Center through the distribution chart of the atmospheric stability index during summer, when convection activity is highest. Finally, we assessed the relationship between lightning occurrence and unstable atmospheric conditions, through predictability analysis performed using the lightning observation data of the Korea Meteorological Administration.

• Journal of the Ergonomics Society of Korea
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• v.32 no.3
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• pp.217-227
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• 2013

Objective: The purpose of this study was to analyze 'response time', 'peak response time' and 'overshoot value' for each muscle by applying the EMG signal to the vehicle response in ISO 7401 and to quantify the response of the driver according to vehicle characteristics by comparing vehicle characteristics and muscle responses of the driver. Background: The Open-loop test defined in international standards ISO 7401 is the only method for evaluating the performance of the vehicle. However, this test was focused only on mechanical responses, not driver's ones. Method: One skilled male driver(22 yrs. experience) was participated in this experiment to measure muscle activities of the driver in transient state. Then the seven muscle signals were applied to calculate 'response time', 'peak response time', and 'overshoot value'. Results: In the analyses of the EMG data, the effects of vehicle type and muscle were statistically significant on the 'response time' and 'peak response time'. Also, the effects of vehicle type, muscle, and lateral acceleration level were statistically significant on the 'overshoot value' in this study. According to the analyses of the vehicle motion data, vehicle motion variable(LatAcc, Roll, YawVel) was statistically significant on the 'response time' and vehicle type, vehicle motion variable, and lateral acceleration level were statistically significant on the 'peak response time', respectively. Conclusion: In the analyses of the 'response time' and 'overshoot value', the data of muscle activities(EMGs) was better index that could evaluate the vehicle characteristic and performance than the data of vehicle motion. In case of peak response time, both EMG and vehicle motion data were good index. Application: The EMGs data from a driver might be applicable as index for evaluation of various vehicle performances based on this study.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.2
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• pp.181-190
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• 2011

The air pollutants from vehicle exhaust gas are affected by many factors including fuel qualities, engine and vehicle technologies, driving patterns. In particular, fuel qualities and after-treatment devices could directly affect the emission level of pollutants. The pollutant reduction characteristics that caused by enforced fuel quality standard were analyzed. Three types of test fuel were selected in accordance with Korean automotive fuel standard in 2006, 2009, 2012 and used for vehicle emission test in chassis dynamometer. European COPERT correction equation of fuel impact was considered as reference information to quantify the vehicle emission test results. The contribution rates of exhaust emission by COPERT correction equation showed that aromatic compounds and oxygen contents in gasoline fuel was most important. In case of diesel fuel, cetane index and polycyclic aromatic compounds accounted for the greater part. The exhaust emission effects by COPERT correction equation revealed that CO and VOC was increased 0.86%, 1.57% respectively in after 2009 gasoline when compared to before 2009 gasoline fuel. In case of light-duty diesel vehicle CO, VOC and PM were decreased in range of 3~7%. The result from this study could be provided for developing future fuel standards and be used to fundamental information for Korean clean air act.

• Environmental Engineering Research
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• v.23 no.1
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• pp.107-113
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• 2018

Air quality and pollution have recently become a major concern; vehicle emissions significantly pollute the air, especially in large and crowded cities. There are various factors that affect vehicle emissions; this research aims to find the most influential factors affecting $CO_2$ and $NO_x$ emissions using Adaptive Neural Fuzzy Inference System (ANFIS) as well as a systematic approach. The modified ANFIS (MANFIS) was developed to enhance modelling and Root Mean Square Error was used to evaluate the model performance. The results show that percentages of $CO_2$ from trucks represent the best input combination to model. While for $NO_x$ modelling, the best pair combination is the vehicle delay and percentage of heavy trucks. However, the final MANFIS structure involves two inputs, three membership functions and nine rules. For $CO_2$ modelling the triangular membership function is the best, while for $NO_x$ the membership function is two-sided Gaussian.

• Environmental Analysis Health and Toxicology
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• v.24 no.3
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• pp.219-229
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• 2009

The purpose of this study is to evaluate the skin whitening effect of Scirpi rhizama ethanol extract (SREE) in an animal model. For the experiment of the study, three brown guinea pigs weighing about 450 g to 550 g were exposed to ultraviolet-B rays on the backs at 500 $mJ/cm^2$ once a week, three consecutive weeks and the total quantity of light was 1,500 $mJ/cm^2$. The artificial tanning spots were divided into six different groups including normal (N), control (C), vehicle control (VC), positive control (PC), experimental 1 (E1, 1% SREE), experimental 2 (E2, 2% SREE) groups. Then, 30 ${\mu}L$ of SREE was transdermaly applied on the artificial tanning spots twice a day and 5 days a week for 8 weeks. With the result of a gross observation, it was found that the degree of pigmentation became apparently thinner in the group applied with E2, compared to the control or the vehicle control group. The melanin index of E2 group was significant lower than the control or the vehicle control group. In the observation with a light microscope, it was found that the degree of melanin pigmentation and S-100 protein expression considerably decreased in the groups applied with SREE, compared to the control or the vehicle control group. With the numerical analysis of melanin pigmentation and S-100 protein expression by using image-analysis software, it was found that the tendency was coincide with the results of microscopic observation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1611-1617
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• 2013

Information about trafficability or the condition of road with regard to its being traveled over by vehicles is one of the most critical factors for roadway operation in winter. Specifically, when traveling on snowy or icy surfaces, the traction force varies per vehicle type including tire types, geometric characteristics of roads, and conditions of road surfaces. In general, front-wheel drive or four-wheel drive vehicles have better traction performance on snowy or icy surface than rear-wheel drive vehicles, and the latter type vehicle causes more serious traffic congestion when there is unexpected snowfall. Thus, traffic information regarding trafficability with respect to vehicle types, geometric characteristics of roadway sections, and roadway surface conditions can provide a foundation to make a decision whether to use the associated roadway sections for roadway operators as well as users. Based on the preceding premise, the objective of this study is to present a methodology for developing a trafficability index with respect to vehicle types, geometric characteristics of roadway sections, and roadway surface conditions.

• Journal of The Korean Society of Grassland and Forage Science
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• v.44 no.3
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• pp.165-172
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• 2024

Italian ryegrass (IRG) has become a vital forage crop due to its increasing cultivation area and its role in enhancing forage self-sufficiency. However, its production is susceptible to environmental factors such as climate change and drought, necessitating precise yield prediction technologies. This study aimed to assess the growth characteristics of IRG and predict dry matter yield (DMY) using vegetation indices derived from unmanned aerial vehicle (UAV)-based remote sensing. The Green Leaf Index (GLI), normalized difference vegetation index (NDVI), normalized difference red edge (NDRE), and optimized soil-adjusted vegetation index (OSAVI) were employed to develop DMY estimation models. Among the indices, GLI demonstrated the highest correlation with DMY (R² = 0.971). The results revealed that GLI-based UAV observations can serve as reliable tools for estimating forage yield under varying environmental conditions. Additionally, post-winter vegetation coverage in the study area was assessed using GLI, and 54% coverage was observed in March 2023. This study assesses that UAV-based remote sensing can provide high-precision predictions of crop yield, thus contributing to the stabilization of forage production under climate variability.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.3
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• pp.247-255
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• 2021

Individual passenger transfer information is not included in Seoul metropolitan subway Automatic Fare Collection (AFC) data. Currently, basic data such as travel time and distance are allocated based on the TagIn terminal ID data records of AFC data. As such, knowledge of the actual path taken by passengers is constrained by the fact that transfers are not applied, resulting in overestimation of the transport index. This research proposes a method by which a transit path that connects the TagIn and TagOut terminal IDs in AFC data is determined and applied to the transit index. The method embodies the concept that a passenger's line of travel also accounts for transfers, and can be applied to the transit index. The path selection model for the passenger calculates the line of transit based on travel time minimization, with in-vehicle time, transfer walking time, and vehicle intervals all incorporated into the travel time. Since the proposed method can take into account estimated passenger movement trajectories, transport-related data of each subway organization included in the trajectories can be accurately explained. The research results in a calculation of 1.47 times the values recorded, and this can be evaluated directly in its ability to better represent the transportation policy index.