• Journal of Power Electronics
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• v.12 no.5
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• pp.715-722
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• 2012

New discrete time domain models for the peak current controlled (PCC) power LED drivers in continuous conduction mode include for the first time the effects of the time delay in the pulse-width-modulator. Realistic amounts of time delay are found to have significant effects on the average output LED current and on the critical inductor value at the boundary between the two conduction modes. Especially, the time delay can provide an accurate LED current for the PCC buck converter with a wide input voltage. The models can also predict the critical inductor value at the mode boundary as functions of the input voltage and the time delay. The overshoot of the peak inductor current due to the time delay results in the increase of the average output current and the reduction of the critical inductor value at the mode boundary in all converters. Experimental results are presented for the PCC buck LED driver with constant-frequency controller.

• Journal of the Korean Society of Safety
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• v.24 no.1
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• pp.69-77
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• 2009

This paper reports the aging driver traffic accident severity modeling results. For the modeling, Poisson regression approach is applied using the data set obtained from the Korea Transportation Safety Authority's simulator-based driver aptitude test results. The test items include the estimations of moving objects' speed and stopping distance, drivers' multi-task capability, and kinetic depth perception and so on. The resulting model with the response variable of equivalent property damage only(EPDO) indicated that EPDO is significantly influenced by moving objects' speed estimation and drivers' multi-task capabilities. More interestingly, a comparison with the younger driver model revealed that the degradation of such capabilities may result in severer crashes for older drivers as suggested by the higher estimated parameters for the older driver model.

• International Journal of Highway Engineering
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• v.15 no.1
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• pp.135-141
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• 2013

PURPOSES: In this study, as part of an effort to develop HUD for public transit, it is proposed that the decision of order priority of contents which will be disposed to bus drivers through HUD for public transit using AHP(Analytic Hierarchy Process) technique. METHODS: In AHP analysis method brainstorming, factor analysis, hierarchical structuring, and weighting analysis were performed by applying a classical analysis method. RESULTS: By the result of analysis it is shown that unlike car drivers, bus drivers prefer information related to bus intervals, bus stop, and door open and close to information related to vehicle running. Also, bus stop information and bus interval information were ranked as first and second place in order priority of HUD contents for public transit by experts. CONCLUSIONS: This method of selecting order priority of HUD contents for public transit can provide a basic foundation for selecting order priority of traffic information contents as well as other HUD contents.

• Science of Emotion and Sensibility
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• v.24 no.4
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• pp.53-68
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• 2021

The continuous development of in-vehicle information systems in recent years has dramatically enriched drivers' driving experience while occupying their cognitive resources to varying degrees, causing driving distraction. Under this complex information system, managing the complexity and priority of information and further improvement in driving safety has become a key issue that needs to be urgently solved by the in-vehicle information system. The new interactive methods incorporating the augmented reality (AR) and head-up display (HUD) technologies into in-vehicle information systems are currently receiving widespread attention. This superimposes various onboard information into an actual driving scene, thereby meeting the needs of complex tasks and improving driving safety. Based on the qualitative research methods of surveys and telephone interviews, this study collects the information needs of the target user groups (i.e., beginners and skilled drivers) and constructs a three-mode information database to provide the basis for a customized AR-HUD interface design.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.1223-1230
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• 2009

In the construction industry, Case-Based Reasoning (CBR) is considered to be the most suitable approach and determining the attribute weights is an important CBR problem. In this paper, a method is proposed for determining attribute weights that are calculated with attribute relation. The basic items of consideration were qualitative and quantitative influence factors. These quantitative factors were related to the qualitative factors to develop a Cost Drivers-structural equation model which can be used to estimate construction cost by considering attribute weight. The process of determining the attribute weight-structural equation model consists o 4 phases: selecting the predominant Cost Drivers for the SEM, applying the Cost Driers in the SEM, determining and verifying the attribute weights and deriving the Cost Estimation Equation. This study develops a cost estimating technique that complements the CBR method with a Cost Drivers-structural equation model which can be actively used during the schematic estimating phases of construction.

• CRM연구
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• v.3 no.2
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• pp.43-68
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• 2010

One of the recent research trends that universities are increasingly adopting the concept of 'customer' and the customer-oriented strategy has urged us to research enterprise-wide CRM strategy adaptable to university administration. As the first step of CRM strategy for university management, we try to validate the difference of CRM strategic factors among university types. Drawing upon both CRM process and customer equity drivers, which have been recognized as core frameworks for CRM strategy, we developed those survey instruments adoptable into university industry, and validated statistically-significant difference among 12 types of university group constructed by the levels of university evaluation and the location of the universities. We collected 261 responses from 177 universities from all over the country and analyzed the data to see the levels of CRM processes consisting of customer acquisition, retention, and expansion, and customer equity drivers consisting of value equity, brand equity, and relationship equity by using multivariate ANOVA(MANOVA). The result confirms the explicit differences of the levels of CRM processes and customer equity drivers between the groups by university evaluation levels(high/middle/low). However, the analysis failed to show the significant differences of those between the group by university locations(the capital/the suburbs/the six megalopolises/other countries). More specifically, the level of activities for customer acquisition and retention of the universities in the higher-graded group are significantly different from those in the lower-graded group from the perspective of CRM process. In terms of customer equity drivers, the levels of both brand equity and relationship equity of the higher-graded group are significantly higher than those of both middle and lower-graded group. In addition, we found that the value equity between the higher and lower-graded groups, and the brand equity between the middle and lower-graded groups are different each other. This study provides an important meaning in that we tried to consider CRM strategy which has been mainly addressed in profit-making industries in terms of non-profit organization context. Our endeavors to develop and validate empirical measurements adoptable to university context could be an academic contribution. In terms of practical meaning, the processes and results of this study might be a guideline to many universities to build their own CRM strategies. According to the research results, those insights could be expressed in several messages. First, we propose to universities that they should plan their own differentiated CRM strategies according to their positions in terms of university evaluation. For example, although it is acceptable that a university in lower-level group might follow the CRM process strategy of the middle-level group universities, it is not a good idea to imitate the customer acquisition and retention activities of the higher-level group universities. Moreover, since this study reported that the level of universities' brand equity is just correlated with the level of university evaluation, it might be pointless for the middle or lower-leveled universities if they just copy their brand equity strategies from those of higher-leveled ones even though such activities are seemingly attractive. Meanwhile, the difference of CRM strategy by university position might provide universities with the direction where they should go for their CRM strategies. For instance, our study implies that the lower-positioned universities should improve all of the customer equity drivers with concerted efforts because their value, brand, and relationship equities are inferior compared with the higher and middle-positioned universities' ones. This also means that they should focus on customer acquisition and expansion initiatives rather than those for customer retention because all of the customer equity drivers could be influenced by the two kinds of CRM processes (KIm and Lee, 2010). Surely specific and detailed action plans for enhancing customer equity drivers should be developed after grasping their customer migration patterns illustrated by the rates of acquisition, retention, upgrade, downgrade, and defection for each customer segment.

• International Journal of Highway Engineering
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• v.13 no.3
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• pp.167-176
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• 2011

This study's purpose is to analyse factors of determination about detouring for makinga standard model in regard of unfavorableness and uncertainty when unspecified individual recipients make a decision at the time of course detour. In order to achieve this, we surveyed SP investigation whether making a detour or not for drivers as a target who take a high way and National highway. Based on this result, we analysed detour determination factors of drivers, establishing a combination model of Decision Tree and Neural Network model. The result demonstrates the effected factors on drivers' detour determination are in ordering of the recognition of alternative routevs, reliable and frequency of using traffic information, frequency of transition routes and age. Moreover, from the outcome in comparison with an existing model and prediction through undistributed data, the rate of combination model 8.7% illustrates the most predictable way in contrast with logit model 12.8%, and Individual Model of Decision Tree 13.8% which are existed. This reveals that the analysis of drivers' detour determination factors is valid to apply. Hence, overall study considers as a practical foundation to make effective detour strategies for increasing the utility of route networking and dispersion in the volume of traffic from now on.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.3
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• pp.32-45
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• 2018

This study aims to compare the mutual perception gap on dangerous driving behavior between male and female drivers in multiple aspects, analyze them, and identify factors that trigger this different perception. To understand the mutual perception gap on dangerous driving behavior, DBQ(Driving Behavior Questionnaire) was applied as a rating scale. By applying results into the Co-oreintation model, this study compared the mutual perception gap between male drivers and female drivers and analyze results. In addition, factors that generate the perception gap between both genders were drawn by analyzing factors. This study suggested that objective consistency identified the perception gap that driving behaviors of others were more dangerous between two genders. In addition, subjective consistency was different as both genders assumed that the counterpart's driving behavior takes more risks than their own actual driving behaviors. In regard to the accuracy, men were aware that female driving behaviors are more dangerous than their behaviors. However, female driving behavior assumed by women was consistent with male perception in all factors, which indicated that women perceive men precisely. In addition, results were compared and analyzed in both perspectives of male drivers and female drivers by combining predictive models. Based on these results, both genders perceived that counterpart's driving behavior is more dangerous among both genders.

• Physical Therapy Korea
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• v.4 no.2
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• pp.18-35
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• 1997

The purpose of this study were to determine causes of low back pain in bus drivers who usually work in prolonged sitting position and to find the relationship of back pain with general characteristics and work environmental characteristics, stress symptoms, to com맹re lordosis angle of habitual driving posture and resting posture in low back pain group and non-low back pain group, and to use this result as a basis for improvement of work environment and comprehensive rehabilitative management of low back pain. Ninety-eight bus drivers were selected from the membership of an urban transit union in Seoul. These informations were collected from May 1, 1997 to May 25, 1997 by means of structured questionnaires and X-ray findings. These data were analyzed by $x^2$ test, t-test, logistic regression using SAS. The major results were as follows: 1. Of the respondents, 66.3% of bus drivers were found to be experiencing back pain. 2. Of the respondents of low back pain groups, 78.5% reported that major cause of low back pain was due to prolonged sitting. 3. The group with experiences of frequent or continuous vibration had more low back pain (p<0.05). There were no significant differences among other work environmental factors. 4. Average stress score was significantly higher in the group with low back pain than in the group without low back pain (p<0.05). 5. The results of the logistic regression analyses were statistically significant vibration from seat and stress score among the risk factors (p<0.05). 6. Averaged lordosis angle of habitual driving posture was $7.6{\pm}14.9$ degrees in low back pain group, $16.5{\pm}8.7$ degrees in non-low back pain and averaged lordosis angle of resting sitting posture was $10.8{\pm}13.7$ degrees in low back pain, $18.9{\pm}9.6$ degrees in non-low back pain group but the difference in mean lordosis angles of two groups was not statistically significant. The results of this study indicate that professional drivers developed chronicity of low back pain due to unfit seat, poor habitual posture and stress from vibration or other risk factors. Therefore, there is need to improve work environment, i.e. enough resting, to set a seat to support lumbar spine properly and to provide comprehensive rehabilitation program including early diagnosis, proper treatment and education for self help management.

• The Journal of the Korea Contents Association
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• v.14 no.11
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• pp.249-259
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• 2014

This study has analyzed the factors that influence the safety consciousness of school bus drivers at Child Care Centers. To achieve this, 276 directors and drivers of owner-operator who drives the school bus at Child Care Centers in Chungnam, Chungbuk and Daejeon area were selected as study subjects. For the data analysis, PASW Statistics 18.0 was used. The main results of this study are as follows. The level of safety consciousness of directors and drivers of owner-operator were 6.46 and 6.82 respectively showing that drivers of owner-operator were significantly higher. Second, the factors that influence the safety consciousness were shown to be significantly different for each group. The factors that influence the safety consciousness of directors were shown in the order of whether or not the accident was experienced, safety-seeking motivation, sensation-seeking disposition, safety consciousness of caregivers, perception-motor skill. The factors that influence the safety consciousness of drivers of owner-operator were shown in the order of safety-seeking motivation, health status, daily driving hours, economic status, safety consciousness of caregivers. Based on these results, several ways were suggested to improve the safety consciousness of school bus drivers at Child Care Centers and prevent the traffic accidents.