• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.1
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• pp.63-73
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• 2024

Autonomous vehicles at Levels 3 to 5, currently under global research and development, seek to replace the driver's perception, judgment, and control processes with various sensors integrated into the vehicle. This integration enables artificial intelligence to autonomously perform the majority of driving tasks. However, autonomous vehicles currently obtain temporary driving permits, allowing them to operate on roads if they meet minimum criteria for autonomous judgment abilities set by individual countries. When autonomous vehicles become more widespread in the future, it is anticipated that buyers may not have high confidence in the ability of these vehicles to avoid hazardous situations due to the limitations of temporary driving permits. In this study, we propose a method for grading the judgment abilities of autonomous vehicles based on a driving simulator experiment comparing and evaluating drivers' abilities to avoid hazardous situations. The goal is to derive evaluation criteria that allow for grading based on specific scenarios and to propose a framework for grading autonomous vehicles. Thirty adults (25 males and 5 females) participated in the driving simulator experiment. The analysis of the experimental results involved K-means cluster analysis and independent sample t-tests, confirming the possibility of classifying the judgment abilities of autonomous vehicles and the statistical significance of such classifications. Enhancing confidence in the risk-avoidance capabilities of autonomous vehicles in future hazardous situations could be a significant contribution of this research.

• Korean Journal of Culture and Social Issue
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• v.14 no.2
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• pp.1-19
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• 2008

This research investigated the influences of excessively careful driving as well as chronic disease and medications on dangerousness of traffic accident in elderly drivers. Ninety-one drivers aged 65 years and older participated in the research. To evaluate the driving behavior, we used the self-rating on driving ability questionnaire asking driving speed, the amount of driving and driving situation adaptability' and surveyed the drive career, the number of violations and accidents experience(crash, crashed) for last three years. A review of the driving patterns of elderly drivers showed that the speed and amount of driving were decreased by increasing age. 'Driving- Situational Adaptability (DSA)' consisted of 2 factors such as 'Social Environment(SE)' and 'Physical Environment(PE)'. Elderly drivers reported that their confidence level was lower in PE than in SE. Moreover they had higher difficulty and stress in PE than in SE. DSA of elderly drivers had significant correlations with 'crash' and 'crashed'. This implies that excessively careful driving of elderly drivers directly associated with accidents. Elderly drivers who have nervous system disease or gastritis had more crash accidents. The majority of elderly drivers which take medicine by chronic disease don't think that medications give don't difficulty or inconvenience in driving and constantly drives during a term of taking medicine.

• Journal of Applied Reliability
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• v.15 no.3
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• pp.139-144
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• 2015

Track drive unit adopted in the small sized excavator generally have been used in the construction equipment under the 10 tons as the driving device with forwarding and reversing of excavator. It is required to study the accelerated life test applied by over torque and speed to test the durability life test reflected the many driving modes of small sized excavator and also need to equip the comprehensive performance and life test equipments to do the various performance tests. This study had analyzed the failure modes of the components, and calculated the equivalent loads investigated the used loads in the real field conditions and elicits the acceleration factor adopted in the inverse power model. Also, this study have considered the changes of the acceleration factor and the durability test time in the case of the rotary group and the bearing through analyzing the main failure modes. It was calculated the no failure test time about 2 samples and confidence level 90% and elicited the accelerated life time 720 hours.

• Advances in environmental research
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• v.9 no.2
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• pp.123-133
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• 2020

A time series dataset was conducted to ascertain the effect of water table on the variability in and emission of CH₄ and CO₂ concentrations at a closed landfill site. An in-situ data of methane/carbon dioxide concentrations and environmental parameters were collected by means of an in-borehole gas monitor, the Gasclam (Ion Science, UK). Linear regression analysis was used to determine the strength of the correlation between ground-gas concentration and water table. The result shows CH₄ and CO₂ concentrations to be variable with strong negative correlations of approximately 0.5 each with water table over the entire monitoring period. The R² was slightly improved by considering their concentration over single periods of increasing and decreasing water table, single periods of increasing water table, and single periods of decreasing water table; their correlations increased significantly at 95% confidence level. The result revealed that fluctuations in groundwater level is the key driving force on the emission of and variability in groundgas concentration and neither barometric pressure nor temperature. This finding further validates the earlier finding that atmospheric pressure - the acclaimed major control on the variability/migration of CH₄ and CO₂ concentrations on contaminated sites, is not always so.

• Korean Journal of Culture and Social Issue
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• v.15 no.2
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• pp.251-271
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• 2009

This research measured a concept of mobility which is included objective travel behavior as well as psychological and physical mechanism that influenced travel behavior. And then, this research examined the relation between mobility and the quality of life in elderly drivers. In research 1, to evaluate the reliability and validity of "Mobility Questionnaire(MQ)", we tested "MQ" to 207 drivers aged 20 years and older. In research 2, we examined the mobility level of elderly drivers. Also we investigated the influence that mobility of elderly drivers impacts on their quaility of life. we used "MQ", "Psychological Well-Being Questionnaire(PWBQ)" to 91 drivers aged 65 years and older. To factor analysis, MQ consisted of 'Safe Driving Ability(ADA)', 'Travel Increase(TI)', 'Travel Decrease(TD)', 'Social Activity(SA)', and 'Driving Situational Adaptability(DSA)'. The amount and speed of driving of elderly drivers reduced driving behavior than other drivers. Also, elderly drivers negatively assessed their physical abilities for safe driving and felt a low confidence in specific driving situation. On the other hand, elderly drivers take parts in social activity constructively. A review of the relation of mobility and quality of life showed that mobility of elderly drivers had positive correlation with PWB. Specially, 'ADA', 'SA', and 'DSA' had significant correlations with PWB of elderly drivers. The mobility of elderly drivers had an effect on 'Autonomy', 'Environmental mastery', 'Self-acceptance', and 'Positive relations with others'.

• Journal of Preventive Medicine and Public Health
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• v.52 no.6
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• pp.355-365
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• 2019

Objectives: In rural areas of Korea, where public transportation infrastructure is lacking and alternative systems are poor, the elderly experience inconveniences in using healthcare, although their need is high. This study aimed to analyze the association between the convenience of transportation and unmet healthcare needs among the rural elderly. Methods: The data used were collected in the 2016 Community Health Survey among rural elderly individuals aged 65 or older. Dependent variable was the unmet healthcare needs, explanatory variable was the convenience of transportation. The elderly were divided into 3 groups: with no driver in the household, with a driver, and the elderly individual was the driver (the self-driving group). Covariates were classified into predisposing, enabling, and need factors. They included gender, age, education, income, economic activity, household type, motor ability, subjective health level, number of chronic diseases, anxiety/depression, and pain/discomfort. The data were analyzed using logistic regression and stratification. Results: A significant association was found between the convenience of transportation and unmet healthcare needs. When examined unadjusted odds ratio of the group with a driver in the household, using the group with no driver as a reference, was 0.61 (95% confidence interval [CI], 0.54 to 0.68), while that of the self-driving group was 0.34 (95% CI, 0.30 to 0.38). The odds ratios adjusted for all factors were 0.69 (95% CI, 0.59 to 0.80) and 0.79 (95% CI, 0.67 to 0.91). Conclusions: We confirmed a significant association between inconvenient transportation and unmet healthcare needs among the rural elderly even after adjustment for existing known factors. This implies that policies aimed at improving healthcare accessibility must consider the means of transportation available.

• Journal of Korean Society of Transportation
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• v.22 no.6
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• pp.145-157
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• 2004

Microscopic freeway simulation models project the uncertain values of performance measures for subject traffic conditions by explaining drivers' driving behavior with lane changing and car-following models. However, the existing lane changing models are limited to gap acceptance oriented passive behavior of drivers and not able to capture more-or-less aggressive driving behavior(e.g. cut-in lane changing) ordinarily obseved in field. This paper suggests the definition of cut-inlane changing and presents its characteristics based on the findings from two different freeway on- and off-ramp sections. In addition, this paper proposes a new lane changing model capable of handling both passive and active drivers' driving behavior for better performance of simulations. The proposed lane changing model was tested with Hanyang Simulatin (HYTSIM), a microscopic freeway simulation program developed for this study. The HYTSIM simulation results reflecting the performance of the proposed lane changing model were compared against the field data. The test results showed that the distribution of gaps collected when vehicles change lanes were statistically identical to the field data at 95% confidence level.

• Convergence Security Journal
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• v.15 no.6_1
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• pp.79-92
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• 2015

It is required to expand area of inter-Korean economic cooperation, being limited to non-military field, to military field and then, to positively promote arms control in order to establish foundation for peaceful reunification in Korean peninsula. Reasons why arms control has not been promoted between South and North Korea in the meantime were such original factors as follows; (1) limit of confidence building between the South and the North, (2) functional limit of arms control itself, (3) institutional structural limit between the South and the North, (4) environmental limit at home and abroad. It is necessary to get out from existing frame and to seek a new paradigm in order to overcome above factors and to realize arms control between the South and the North. First, it is required to have prior political dialog at the South-North high-level talks in order to promote arms control and to exercise 'strategic flexibility' during negotiation and promotion process. For this, 'flexible reciprocity' has to be adopted in compliance with situation and conditions. Second, it is necessary to get out from existing principle of 'confidence building in advance and arms reduction later' but to seek the 'simultaneous driving principle of confidence building and arms reduction' as an eclectic approach. Namely, based on reasonable sufficiency, it is required to promote military confidence building and limited arms reduction in parallel, which is a lower level of arms control. Third, as an advisory body of Prime Minister's Office, it is necessary to install an organization exclusively responsible for arms control and to positively handle arms control issue from the standpoint of national policy strategy. If the South-North high-level talks take place, it is necessary to organize and operate 'South-North Joint Arms Control Promotion Board (tentative name)'. Fourth, it is required to exercise more active diplomatic competence in order to create national consensus on necessity of arms control for peaceful reunification and to form more favorable international environment. Especially, it is necessary to think about how to solve nuclear issue of North Korea together in collaboration with international society and how to maintain balance between ROK-US alliance and Sino-Korean cooperation relations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.55-63
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• 2020

Road traffic noise is a major complaint. Porous pavement (PP) has been proposed as an effective method for reducing road traffic noise, but it has not been applied much due to the lack of quantitative evaluation. In this study, the noise reduction of single-layer porous pavement (SLPP) and double-layer porous pavement (DLPP) was evaluated. The noise was measured using the CPX method, and the driving speed was measured every 10km/h from 50km/h to 80km/h. The differences in noise level between the two PPs were statistically significant. The driving speed had no significant effect on the difference in noise between the two PPs. The DLPP showed a 6.6dB(A) reduction in average and a 6.3dB(A) reduction at the 95% confidence level compared to the SLPP. Reducing noise by 5dB(A) is equivalent to reducing traffic to 1/3 or lowering the vehicle's speed to 1/2. Sensitively, it is possible to recognize a 3dB(A) and 5dB(A) difference. The DLPP and SLPP were very effective in reducing traffic noise.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.8
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• pp.726-734
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• 2007

Generally, a mobile robot is moved by original input programs. However, it is very hard for a non-expert to change the program generating the moving path of a mobile robot, because he doesn't know almost the teaching command and operating method for driving the robot. Therefore, the teaching method with speech command for a handicapped person without hands or a non-expert without an expert knowledge to generate the path is required gradually. In this study, for easily teaching the moving path of the autonomous mobile robot, the autonomous mobile robot with the function of speech recognition is developed. The use of human voice as the teaching method provides more convenient user-interface for mobile robot. To implement the teaching function, the designed robot system is composed of three separated control modules, which are speech preprocessing module, DC servo motor control module, and main control module. In this study, we design and implement a speaker dependent isolated word recognition system for creating moving path of an autonomous mobile robot in the unknown environment. The system uses word-level Hidden Markov Models(HMM) for designated command vocabularies to control a mobile robot, and it has postprocessing by neural network according to the condition based on confidence score. As the spectral analysis method, we use a filter-bank analysis model to extract of features of the voice. The proposed word recognition system is tested using 33 Korean words for control of the mobile robot navigation, and we also evaluate the performance of navigation of a mobile robot using only voice command.