• Journal of Environmental Health Sciences
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• v.41 no.1
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• pp.24-29
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• 2015

Objectives: The objective of this study was to identify determine factors for blood VOCs levels in college students. Methods: Venous blood samples were collected from healthy 29 male and 25 female volunteers. The samples were analyzed with solid-phase microextraction gas chromatography and mass spectrometry. Results: Blood concentrations of benzene, toluene, ethylbenzene, m-,p-xylene, o-xylene were higher in smoking group than in non-smoking group. Geometric means of smoking group and non-smoking group were 0.45 and $0.36{\mu}g/L$ in benzene, 0.82 and $0.47{\mu}g/L$ in toluene, 0.44 and $0.41{\mu}g/L$ in ethylbenzene, 0.49 and $0.39{\mu}g/L$ in m-,p-xylene and 0.47 and $0.43{\mu}g/L$ in o-xylene, respectively. Gender, alcohol drinking, coffee, commuting time (30 minutes) by a car and adjacency between home and road were not associated with increasing blood VOCs concentrations of college students. Conclusion: Smoking habit was significantly associated with blood concentrations of benzene, toluene, ethylbenzene, o-,m-,p-xylene in college students.

• Journal of Korean Academy of Dental Administration
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• v.9 no.1
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• pp.44-50
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• 2021

Owing to the Corona virus (COVID-19) crisis, virtual education has been expanded. Accordingly, this study was conducted to determine the direction of oral health education by examining participants' satisfaction with virtual education and educational media preferences. This study collected data from a Naver Form online survey targeting 290 university students across the country, from May 10 to 31, 2021. The collected data were analyzed using IBM SPSS 20.0. According to the data, satisfaction with virtual classes was 3.36 points in 5-point Likert scale, satisfaction factors were reduced commuting time and money expenditure, and the highest dissatisfaction factor was a decrease in lecture concentration. The media platform that most interested students pursing oral health education was YouTube. The oral health education that participants wished to receive through virtual education included how to prevent tooth decay, how to prevent gum disease, and how to brush teeth. In conclusion, it is necessary to develop various media like Zoom, YouTube, and virtual reality programs so that students feel motivated to utilize oral health education and improve oral health.

• Korean Journal of Artificial Intelligence
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• v.10 no.1
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• pp.9-14
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• 2022

The demand for public bicycles operated by the Seoul Metropolitan Government is increasing every year. The size of the Seoul public bicycle project, which first started with about 5,600 units, increased to 3,7500 units as of September 2021, and the number of members is also increasing every year. However, as the size of the project grows, excessive budget spending and deficit problems are emerging for public bicycle projects, and new bicycles, rental office costs, and bicycle maintenance costs are blamed for the deficit. In this paper, the Azure Machine Learning Studio program and the Boosted Decision Tree Regression technique are used to predict the number of public bicycle rental over environmental factors and time. Predicted results it was confirmed that the demand for public bicycles was high in the season except for winter, and the demand for public bicycles was the highest at 6 p.m. In addition, in this paper compare four additional regression algorithms in addition to the Boosted Decision Tree Regression algorithm to measure algorithm performance. The results showed high accuracy in the order of the First Boosted Decision Tree Regression Algorithm (0.878802), second Decision Forest Regression (0.838232), third Poison Regression (0.62699), and fourth Linear Regression (0.618773). Based on these predictions, it is expected that more public bicycles will be placed at rental stations near public transportation to meet the growing demand for commuting hours and that more bicycles will be placed in rental stations in summer than winter and the life of bicycles can be extended in winter.

• Journal of Korean Society of Transportation
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• v.35 no.6
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• pp.511-524
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• 2017

This study aims to evaluate the availability of ABM (Active-Based Model), FEATHERS, as a policy evaluation tool. To achieve the goal, scenario analysis on flexible working policy was conducted to measure its impact on activity-travel behavior. As a consequence, there seems no significant change in worker's daily life, other than mitigating traffic congestion due to decreasing commuting travel in the rush hour. The result of VKT (vehicle kilometers traveled) shows an opposite pattern according to given household/individual constraints. The scenario analysis on telecommuting indicates a decreasing trend in both travel frequency and distance because of the diminished number of commuting trips. As the activity space of telecommuters is shifted to a residential area, there are more short-distance trips by using non-motorized transport, which leads to decrease in VKT (using a private vehicle). Thus, the sensitivity of VKT by population groups varies due to transport mode shift (between personal and another mode) and growing non-work trips (using a private mode). This study found few things. First, it is necessary to evaluate the details of policy impact by population groups since it can be varied depending on household/individual characteristics. Second, the case study shows a promising performance of ABM as policy measurement that provides reality in policy evaluation. Third, ABM allows us to do more accurate analysis (i.e. time-series analysis by population groups) of policy assessment than those of FSM (Four-Step Model). Lastly, a further effort in data collection, literature review, and expert survey should be made to enhance the accuracy and confidence of future research.

• Journal of the Society of Disaster Information
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• v.14 no.2
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• pp.182-193
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• 2018

Purpose: The purpose of the study is to analyze the relationship between travel behavior and urban spatial characteristics in a hierarchical manner. Method: This study analyzed the relationship between traffic patterns and urban spatial characteristics for 83 cities in Korea by using a hierarchical linear model. Results: It was found that the urban spatial characteristics influenced the choice of transportation mode and travel time with personal attributes. However, the degree of influence on the choice of the means and the time required is relatively low through the policy of changing the city attribute, so the policy effect of mobilizing the land use policy for the traffic is theoretically, but the scale is not bigger than expected. Conclusion: In high density or the bigger scale of the city, the mass transportation system is widely supplied and used, but it does not overcome the drawback that it takes more time than the autos.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2430-2436
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• 2013

This study suggests a method of detecting the still object, which becomes a cause of danger within the crossroad. The Inverse Perspective Transform was performed in order to make the object size consistent by being inputted the real-time image from CCTV that is installed within the crossroad. It established the detection area in the image with the perspective transform and generated the adaptative background image with the use of the moving information on object. The detection of the stop object was detected the candidate region of the stop object by using the background-image differential method. To grasp the appearance of truth on the detected candidate region, a method is proposed that uses the gradient information on image and EHD(Edge Histogram Descriptor). To examine performance of the suggested algorithm, it experimented by storing the images in the commuting time and the daytime through DVR, which is installed on the cross street. As a result of experiment, it could efficiently detect the stop vehicle within the detection region inside the crossroad. The processing speed is shown in 13~18 frame per second according to the area of the detection region, thereby being judged to likely have no problem about the real-time processing.

• Journal of Nutrition and Health
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• v.38 no.10
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• pp.847-855
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• 2005

This study investigated and compared the daily activities and energy expenditure of normally-weighted and obese elementary school children. The participants were 115 boys and 115 girls (6th grade) at ten elementary schools in Busan. Time spent on each activity was evaluated using the twenty-four hour recall method. 1) The general characteristics of the normally-weighted and obese children did not differ, although the normally-weighted children exercised and used stairs more than the obese children.2) Among their classified activities, the children spent most of their time resting, study, leisure, physiology and hygiene, commuting, and housework in that decreasing order. Normally-weighted children spent less time tying down and in conversation with family and friends than obese ones. 3) The children's average activity factors were 1.47 - 1.50. The normally-weighted children's rest energy expenditure (REE) (1391.4 kcal,1264.7 kcal) was less than that of the obese children (1711.4 kcal. 1461.0 kcal) . The normally-weighted children's daily energy expenditure was less than that of the obese, but energy expenditure per body weight was less in obese children than in the normally-weighted. In conclusion, sedentary activities and energy expenditure per body weight was less in the obese compared to the normally-weighted children. Programs to help children perceive and practice desirable physical activities should be suggested for prevention of obesity in children. (Korean J Nutrition 38(10): 847$\sim$855,2005)

• Journal of the Korea Society of Computer and Information
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• v.15 no.9
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• pp.19-24
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• 2010

The number of automobiles are continuously increasing in Korea since 1990's and it causes frustrating commuting traffic and holyday traffic. Meanwhile, the obsolete traffic signal control system is still under static control based on the aggregated traffic statistics thus it is not sufficiently adaptive in real world traffic situation that changes in real time. Thus, in this paper, we propose an adaptive signal control system using fuzzy control technology that can react to real time traffic situations. The method computes the priority of signal phases based on the number of waiting automobiles and occupying time on intersection using fuzzy membership functions. The phase with highest priority obtains "proceed" signal. Also, the duration of this "proceed" signal is determined based on the ratio of number of waiting automobiles of given phase and total number of waiting automobiles on intersection. In experiment, we show that the proposed fuzzy control system is better than the static control system for all sorts of traffic congestion situations by simulation.

• Journal of the Korean Society for Railway
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• v.16 no.5
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• pp.402-409
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• 2013

In metropolitan railway systems, the average commuting time keeps increasing as the scheduled speed increases, and this leads to a decline of rail service usage and competitiveness. Therefore, effective express operation for urban trains is required to improve the scheduled speed. In this study, based on the obtainable time shortening efficiency and economic viability, several express operations are suggested for urban railways and these suggestions are compared by considering high performance trains with acceleration/deceleration and maximum speed improvement. As a result, the optimum express system, which can minimize the cost for sidetrack construction, is suggested.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.1
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• pp.28-38
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• 2019

The smart card data stores the transit usage records of individual passengers. By using this, it is possible to analyze the traffic demand by station and time. However, since the purpose of the trip is not recorded in the smart card data, the demand for each purpose such as commuting, school, and leisure is estimated based on the survey data. Since survey data includes only some samples, it is difficult to predict public transport demand for each purpose close to the complete enumeration survey. In this study, we estimates the purposes of trip for individual passengers using the smart card data corresponding to the complete enumeration survey of public transportation. We estimated trip purposes such as commute, school(university) considering frequency of O-D, duration, and departure time of a passenger. Based on this, the passengers are classified as workers and university students. In order to verify our methodology, we compared the estimation results of our study with the patterns of the survey data.