• International conference on construction engineering and project management
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• 2005.10a
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• pp.417-423
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• 2005

Contractor's opportunistic bidding behavior refers to contractor's deliberate low-bid, which cannot accord with the cost, and expectation for beyond-contractual reward (BCR), the compensation earned through cutting corners or claims after undertaking the construction project. This research applies System Dynamics to develop a model of contractor's pricing with consideration for dimensions of "cost", "market competition", and "BCR". Iterative computer simulations were performed to analyze the effects of contractor's pricing on the market price. The results were then examined by statistical analysis on data collected from 44 highway projects in Taiwan. It is found that the critical force driving the contractors to bid opportunistically is their excessive expectations in BCR under the current environment. Within the price competition mechanism, if the problem of BCR exists, even if the bidding system is further improved, contractors would still prefer opportunistic bidding behavior, and eventually make the whole construction industry operate ineffectively. Therefore, it is crucial to remedy the aforementioned BCR problem by more effective management policy.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.395-398
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• 1996

A Global Positioning System(GPS) in an automobile can provide navigational information for identifying the current location of the automobile and helping the drive determine a desirable route to the destination. Usefulness of such a system depends on many design factors. This study examined two critical design factors from a human factors standpoint. The rotation methods and updating schemes of a map were manipulated in a simulated driving environment. Design guidelines are suggested based on the experimental results.

• Journal of Biosystems Engineering
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• v.26 no.2
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• pp.93-104
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• 2001

A linear chemigation system, integrating agrichemical appication units of pesticide and fertilizer into an irrigation system, was selected as a suitable model for the cost savings in farm management and automation. Technical designs were conducted in the areas of structure, power, drive, control, and hydraulic systems. An experimental farm was sectioned into the fields of 40m by 200m and systemized with the linear-move chemigation system of 36m in span. The chemigation system consisted of a base unit monitoring and controlling overall operation, and a driving unit traveling linearly and injecting agrichemicals. Monitoring and interlocking systems were utilized against unexpected malfunctions of power, injection and drive systems using radio freuency modems between the units. The system can be also modified to various farm sizes and stationary systems of indoor and outdoor.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.1
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• pp.9-13
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• 2011

The purpose of this study was to investigate the effects of the secondary tasks such as sending text message (STM) and searching navigation (SN) on skin conductance level (SCL) and deviation of vehicle speed during driving. The participants included 30 healthy adults; 14 males aged $25.2{\pm}0.9$ with $1.9{\pm}1.8$ years of driving experiences and 16 females aged $22.6{\pm}1.9$ with $1.2{\pm}0.8$ years of driving experiences. All subjects were instructed to keep a constant speed (80km/h or 100km/h). SCL and deviation of vehicle speed were measured during driving only and driving with secondary tasks. SCL and deviation of vehicle speed were more increased during the driving with secondary tasks than driving only. Secondary tasks increased an activation of sympathetic nerve system and decreased driving performance. However, there were no significant differences in the SCL and deviation of vehicle speed according to gender and speed.

• Journal of the Korean Society of Systems Engineering
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• v.11 no.2
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• pp.137-146
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• 2015

This paper addresses the definition of the driver's functions for an automated vehicle of level 3, as defined by the Society of Automotive Engineers. By combining the constituent systems surrounding the automated vehicles in specific use cases, their interactions could be refined in a stepwise approach. This approach enables traceability of interactions between drivers, automated driving systems, and other constituent systems.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.1D
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• pp.33-42
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• 2011

The types of the accidents caused by intra-city buses and the changing tendencies of driving attitudes are analyzed before-and-after semi-public management system of intra-city bus system is implemented. On the basis of analysis, the measures on the decrease of traffic accidents are considered and the results are as follows. First, it showed that the traffic accidents decreased generally as a result of definition of the progresses of traffic accidents of intra-city buses before-and-after the system is implemented and with the passing of time after the system was operated. Second, the factors which influence the decrease of traffic offenses before-and-after semi-public management system of intra-city bus are the decease of violation, safe driving duty and the job security. Also the cause which mostly influence to the decrease of traffic accidents is defined. Finally, the measures of decrease of traffic accidents are arranged and proposed as a result of PROXSCAL method.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.305-306
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• 2022

In accordance with the Act on Punishment of Serious Disasters, terminal operators are required to establish and operate a safety and health management system such as manpower and budget necessary for disaster prevention, and establish and implement measures to prevent recurrence in the event of a disaster. This is a study on how to use the port facility safety management system linkage to prevent safety accidents in port facilities due to the introduction of autonomous driving port equipment and to support decision-making promptly in case of safety accidents.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3D
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• pp.303-311
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• 2010

There have been various forms of systems such as a digital speedometer or a black box etc. to meet the social requirement for reducing traffic accidents and safe driving. However that systems are based on after-accident vehicle data, there is limit to prevent the accident before. So in our previous research, by storing, analyzing the Vehicle-dynamic information coming from driver's behavior, we are developing the decision-device which could provide driver with Alerting-Information in real-time to enhance the driver's safety drive. but the performance valuation is not yet executed. Finally, this study developed positional recognition system by using the DGPS for pre-developed risky driving decision device. The result of test analyzed with the same that the aggregated vehicle dynamics data in DGPS and dangerous risky driving decision device. If the performance of risky driving decision device is verified by precisely positional recognition system, the risky driving management of vehicle would be effected.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.2
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• pp.9-15
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• 2012

The purpose of this study was to investigate the effects of the secondary tasks such as sending text message (STM) and searching navigation (SN) on skin conductance level (SCL) and driving performance of relatively aged and high-experienced drivers. The subjects included 26 taxi drivers; 12 males aged $56.3{\pm}4.4$ with $28.4{\pm}6.4$ years of driving experiences and 14 females aged $55.5{\pm}3.5$ with $19.4{\pm}5.0$ years of driving experiences. All subjects were instructed to keep a constant following distance (30m) from the car ahead and a given vehicle speed (80km/h or 100km/h) in a driving simulator. The relative change of SCL, vehicle velocity deviations, and average following distances were measured during driving only and driving with secondary tasks. The relative change of SCL, average following distance, and vehicle velocity deviation were more increased during the driving with secondary tasks than driving only. The relative change of SCL, vehicle velocity deviation, and average following distance were more affected by driving with 100km/hr than 80km/hr of a given vehicle speed. Secondary tasks increased a work load of drivers in term of SCL change, and decreased driving performance in terms of the vehicle velocity deviation and average following distance.

• Journal of Korean Society of Transportation
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• v.28 no.4
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• pp.73-83
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• 2010

The main objective of this paper is to analyze the factors of a semi-public management system of intra-city bus that influence the decrease of traffic accidents which are caused by intra-city buses and the attitude change of intra-city bus drivers over their driving. The results show that the traffic accidents decreased generally as a result of definition of the progresses and characteristics of traffic accidents of intra-city buses before-and-after the system is implemented and with the passing of time after the system began operations. Second, the factors which influence the decrease of traffic offenses before-and-after semi-public management system of intra-city bus are the decrease of violations, safe driving, and job security. Also, the causes which mostly influence the decrease of traffic accidents are defined. Finally, the changing degrees of driving attitudes before-and-after the system is implemented and the causes of the changes are determined. The effects on the decrease of traffic accidents before-and-after the system is implemented as well as the problems and the solutions over time are the main products of this study.