• Korean Journal of Construction Engineering and Management
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• v.10 no.1
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• pp.58-68
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• 2009

The purpose of this study is to suggest new subject to satisfy the lack parts of examination course of the existing driving tower crane certificate by using the DACUM method. For this, problems of education for the existing driving tower crane certificate and the existing subjects are examined and, based on these, comparing analysis of new subjects that follows the DACUM method and the existing subjects are conducted. The results of this study that were progressed following the purpose and method at the above are as follow : 1) It is analyzed that the existing subjects for the driving tower crane certificate could not be applied to construction fields immediately and the education to deal with disorders when driving the tower cranes. 2) The number of the subjects that have been advanced following the DACUM method is seven and those consist of five theoretical subjects and two practical subjects. It is analyzed that the developed and suggested subjects can be used in construction fields when considering the theoretical and practical parts in no time.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.3
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• pp.225-232
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• 2017

Several maintenance issues related to cavitation erosion and fatigue cracks in the water turbine subcomponents of pumped-storage plants, such as a runner and a draft tube, have been reported in the past. Generally, the pumped-storage plants provide ancillary services, such as black-start and system stabilization. The ancillary services are responsible for cyclic low opening operation of the guide vanes. It has been empirically established that this low opening operation further damages the water turbine subcomponents. In this study, the acceleration effect of the low opening operation on the cavitation erosion and fatigue of the water turbine is quantitatively assessed through finite element flow analysis, finite element stress analysis, and fatigue analysis. As a result of the assessment, it is identified that the cavitation potential increases and the turbine efficiency decreases with a decrease in the opening of the guide vane. Also, the low opening operation has an insignificant effect on the fatigue even though it increases the maximum stress values at the runner blade roots.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.5
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• pp.15-28
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• 2020

After the driver test was simplified in 2011, there were criticisms of its inadequate level of safety standards. A new and improved test was adopted in December 2016. This study investigated the impact of the changes to the test on safety, and analyzed traffic safety statistics and sensory evaluations to determine the effect of the improved driving license test. The analysis concluded that the current test has a proper discrimination and that fairness has increased considerably. The analysis also identified measures that, once adopted, will improve the conduct of driver tests. In the future, it will be necessary to conduct more in-depth studies and to review cases of advanced countries.

• Korean Journal of Culture and Social Issue
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• v.22 no.1
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• pp.19-39
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• 2016

Though research has shown that public transportation drivers experience greater burnout than other drivers, the sources of their burnout and possible mediators remain largely unknown. In response, in this study we investigate the relationships among sensation seeking, Type A driving behavior, and meaning of work to elucidate the burnout experienced by bus drivers in Gyeonggi-do, South Korea. To collect data regarding these relationships, 188 bus drivers answered a questionnaire involving the sensation seeking scale, burnout scale, and meaning of work scale. Results showed that Type A driving behavior mediated the relationship between sensation seeking and burnout, while meaning of work moderated the mediated model. These findings demonstrate that sensation-seeking bus drivers tend to experience greater burnout given their tendency to exhibit Type A driving behavior, and this relationship depends on perceived meaning of work. This study therefore contributes meaningful information and outlines significant implications in understanding drivers' burnout.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.555-560
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• 2008

Extraction was performed to prepare ash-free coal from low rank coal under the temperature of $200-430^{\circ}C$ and initial pressure of 0.1MPa. Three kinds of coal samples with different rank were used and N-methyl-2-pyrrolidinone(NMP, polar), 1-methyl naphthalene(I-MN, non-polar), Light Cycle Oil(LCO, non-polar) were used as solvents. Results showed that higher extraction yield could be obtained with NMP than with 1-MN and LCO, but the ash concentration shows minimun in the case of 1-MN. Three operation modes were compared, that is, idle, agitation and ultrasonic extraction mode. From the results, it was found that the extraction yield and ash concentration were 70.09% and 1.03% under the agitation mode, 80.7% and 0.76% under the ultrasonic operation mode respectively in the case of NMP used at the temperature of $350^{\circ}C$. Similar results were obtained with 1-MN. Effect of ultrasonic on the extraction was estimated as 15-20% increase in the yields and 26% reduction in the ash concentration.

• Journal of Korean Society of Transportation
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• v.30 no.6
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• pp.27-36
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• 2012

In Korea, 28,641 cases of traffic accidents were caused by drunk driving in 2010. These statistics accounted for 12.62% of total number of traffic accidents. Moreover, the percentages of deaths and injuries from them were nearly 15% of those from whole traffic accidents. While police has emphasized enforcement efforts in order to reduce drunk driving, culture generous to drunk driving in addition to the absence of an appropriate intervention system for habitual drunk drivers have contributed to the increasing number of the drunk driving accidents in Korea. This study examined specific behavioral changes in drunk driving by comparing drivers' behavior pattern in non-alcoholic condition to those in alcoholic condition, using a psychomotor test and a driving simulator. In the psychomotor test measuring participants' reactions to the target stimulus, it was revealed that participants' correct responses were decreased, false responses were increased, and no responses also were increased after drinking. Furthermore, in the driving simulator performance after drinking, not only driving speed was faster but also the deviation of an accelerator pedal pressure and of the vehicle's lateral position were much increased. These results indicated that alcohol consumption would impair visio-cognitive ability and deteriorate driving safety. Finally, the implications and limitations of our findings and suggestions for the future research were discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.293-302
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• 2019

This study systematically analyzed computer-based driving intervention programs for seniors, to provide the academic background for driving intervention for seniors. Articles published from January 2009 till December 2018 were researched and analyzed. 'PubMed, Google Scholar, and Science Direct' were used to search articles published overseas, and 'RISS, KERIS, and KISS' searched for articles published in Korea. Based on the inclusion and exclusion criteria, totally 359 papers were retrieved, and 10 articles were finally analyzed; 8 articles (80%) were evidence level I, and 2 articles (20%) were evidence level III. Amongst the computer-based interventions, driving simulators (70%) were the most common, followed by two video image training (20%) and one Nintendo Wii program (10%). In most studies, driving simulators trained the cognitive and visual abilities of seniors and enhanced their abilities to cope with risk situations under various simulated circumstances. Other interventions were also reported to have a positive effect. For evaluating elderly drivers, the driving performance evaluation using a driving simulator was the most common; in addition, evaluations of attention, space-time ability, cognitive function, risk perception, depression and anxiety were also commonly used. We believe that it is appropriate to employ computer-based driving intervention programs for seniors to train and evaluate various domains. We expect that these interventions can be used as an effective tool for safe driving.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.1
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• pp.141-158
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• 2022

Currently, there are some aptitude test systems for older drivers in Korea. However, there are no methods and systems to evaluate the real driving ability for older drivers based on filed driving test. This study was conducted to investigate the availability to use the driving course test used for driving license for identifying difference in driving ability of older and non-older drivers. For the research purpose, filed experiments were conducted using the real driving course test site and evaluation times used in the field. In particular, driving behavior data that obtained from the experiments for two driver groups, older and non-older drivers, were analyzed and compared. From several statistical analyses of driving ability and vision and cognitive ability, it was found that the currently used driving course test site and evaluation times were not appropriated to identify driving ability deficiency of older drivers. To solve the problem, this study developed five evaluation items to identify driving ability deficiency of older drivers using the currently used driving course test site. It was also found that the developed five evaluation items have statistically significant correlation with vision and cognitive ability.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.5
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• pp.329-335
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• 2008

Recently, super high-speed motor drives have been available due to the development of power electronics technology And they are used in various fields of industry because of their advantages. This paper describes the control algorithm for a permanent magnet synchronous motor(PMSM) drive at the speed of 118,000r/min using DSP and IGBT inverter. Hall sensors are implemented to measure the rotor position and speed, and a speed observer is used to reduce the performance deterioration caused by the low resolution of hall sensors. To enhance the output power capacity in the high-speed operating region, a flux weakening controller which also can work as an anti-wind up controller is used. Computer simulations and experiments are peformed to validate the proposed method.

• Nuclear Engineering and Technology
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• v.18 no.3
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• pp.209-217
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• 1986

The inlet coolant temperature reduction technique has been used to extend the load follow operation further in the end-of-cycle-life(EOL). In order to simulate the technique and calculate the nuclear characteristics of a PWR core according to the load follow operation, the three dimensional computing system has been established. The analysis was performed in both MINB and SPINR modes of typical 12-3-6-3 locad follow operation for the EOL of KNU-1 plant. Moreover, the capability of return-to-power has been also tested for those two modes with the system analysis by the RETRAN-02 code. The results show that it has no difficulty to extend the load follow operation further in the EOL by applying the inlet coolant temprature reduction, and also the spinning reserve capacity(SRC) increases by 13% in MINB mode and 14% in SPINR mode Bore that used by control rods only, for 14$^{\circ}$ F drop in the inlet temperature.