• 연구논문집
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• s.33
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• pp.89-97
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• 2003

A barrel cam is used as a very important part of an index drive unit. The index drive unit must have an intermittent-rotational motion. The barrel typed cam and roller gear mechanism has the advantages of high reliability to perform a prescribed motion of a follower. This paper proposes a new method for the shape design of the barrel cam and also a CAD program is developed by using the proposed method. As defined in this paper, the relative velocity method for the shape design calculates the relative velocity of the follower versus cam at a center of roller, and then detemines a contact point by using the geometric relationships and the kinematic constraints, where the direction of the relative velocity must be parallel to a common tangential line at the contact point of two independent bodies, i.e. the cam and the follower. Then, the shape of the cam is defined by the coordinate transformation of the trace of the contact points. This paper presents shape design of the barrel cam in order to prove the accuracy of the proposed methods

• Journal of the Korean Society for Precision Engineering
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• v.19 no.8
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• pp.47-54
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• 2002

A barrel cam is used as a very important part of an index drive unit. The index drive unit must have an intermittent-rotational motion. The barrel typed cam and roller gear mechanism has the advantages of high reliability to perform a prescribed motion of a follower. This paper proposes a new method for the shape design of the barrel cam and also a CAD program is developed by using the proposed method. As defined in this paper, the relative velocity method for the shape design calculates the relative velocity of the follower versus cam at a center of roller, and then determines a contact point by using the geometric relationships and the kinematic constraints, where the direction of the relative velocity must be parallel to a common tangential line at the contact point of two independent bodies, i.e. the cam and the follower Then, the shape of the cam is defined by the coordinate transformation of the trace of the contact points. This paper presents two examples for the shape design of the barrel cam in order to prove the accuracy of the proposed methods.

• Korean Management Science Review
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• v.30 no.2
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• pp.97-106
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• 2013

Of the new and renewable energies currently being pursued domestically, wind energy, together with solar photovoltaic energy, is a new core growth driver industry of Korea. As of May 2012, 33 wind farms at a capacity of 347.8MW are in operation domestically. The purpose of this study was to compare and analyze how efficiently each operational wind farm is utilizing its power generation capacity and the weather resource of wind. For this purpose, the study proceeded in 3 phases. In phase 1, ANOVA analysis was performed for each wind farm, thereby categorizing farms according to capacity, region, generator manufacturer, and quantity of weather resources available and comparing and analyzing the differences among their operating efficiency. In phase 2, for comparative analysis of the operating efficiency of each farm, Data Envelopment Analysis (DEA) was used to calculate the efficiency index of individual farms. In the final phase, phase 3, regression analysis was used to analyze the effects of weather resources and the operating efficiency of the wind farm on the power generation per unit equipment. Results shows that for wind power generation, only a few farms had relatively high levels of operating efficiency, with most having low efficiency. Regression analysis showed that for wind farms, a 1 hour increase in wind speeds of at least 3m/s resulted in an average increase of 0.0000045MWh in power generation per 1MW generator equipment capacity, and a unit increase in the efficiency scale was found to result in approximately 0.20MWh power generation improvement per unit equipment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.4D
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• pp.291-303
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• 2012

In order to lead safe driving, it is better to provide dynamic and detailed information on how the driver using the relevant road should behave as concerning movements of individual car rather than providing monotone and static information of reducing of speed to unspecified drivers. Assuming road and communication of highway where real-time collection and transfer of information on vehicles and road traffic status is possible, the purpose of this study was to provide real-time safe distance by considering road traffic condition such as road condition and driving condition, travel speed and distance between preceding/following vehicles. We intended to provide basic information about dangerous situation by defining different values of condition based column ($C_{condition}$) in accordance with the road surface condition, based on which Real-time Safety Distance Index(RSDI) is to be calculated comprehensively reflecting speed of preceding and following vehicles, distance between vehicles, vertical alignment and road surface condition on the scope of expression column ($C_n$). We intended to enable the driver to secure safety by providing the calculated Real-time Safety Distance Index (RSDI) so that the driver can intuitively sense and sufficiently cope with a dangerous situation where collision of vehicles may occur. The calculated RSDI value is comprised of 30 unit columns and will be provided to the driver being divided into risk evaluation grades of 3 predetermined steps, 'warning', 'dangerous' and 'normal'.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.21 no.1
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• pp.49-56
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• 2015

Background: Although many of those who drive for a living are exposed to repetitive and awkward posture and whole body vibration which cause them cumulative trauma disorder, therapeutic studies related to the problems from the transport unit are still somewhat inadequate. The purpose of this case report is to identify the effect of combined exercise program on patients suffering chronic neck pain caused by long hour of intra-city bus driving. Method: A total of 4 subjects are selected as patients, all of whom have more than 10 years of experience in intra-city bus transportation services. These people have suffered from neck pain for years. We ran the combined exercise program 3 times a week for 4 weeks and respectively evaluated the results after the 2nd and 4th week. We implemented conventional physiotherapy for 40 minutes, another 40 minutes of combined exercise program, and then educated the patients to enable themselves to do active stretching program as a home program. The combined exercise program contained 3 different stages. 1st stage: active stretching program, 2nd stage combined stabilization exercise and strengthening exercise, 3rd stage: proprioceptive exercise Result: After 4 weeks of intervention, there was enhance in the range of motion. $12^{\circ}$ increase in flexion, $10^{\circ}$ in extension, $6^{\circ}$ in lateral flexion respectively, and $10^{\circ}$ in rotation on average. VAS(visual analgue scale) decreased by 33% on average, NDI(neck diability index) by 28% and fatigability by 23%. Conclusion: There were improved results in the range of motion, NDI, VAS, and in fatigability after applying combined exercise program to intra-city bus drivers exposed to whole body vibration and cumulative trauma disorder.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.2D
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• pp.227-235
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• 2011

At present, the characteristics of drivers are not properly considered when informations are provided via VMS even though the Variable Message Signs(VMS) are one of the key information provision medias on the roads. In this study, the driver's psychological response(stress index) was evaluated using a driving simulator for the position of the VMS provided, the contents of the VMS provided, the size of characters on VMS, and types of VMS expression. It was appeared that the stress is the least when the position of the VMS provided 1.5km proceeded from exit, the contents of the VMS provided are time information and types of VMS expression are character form respectively and the size of characters on VMS is appeared not important. In addition, the change of the users' satisfaction level was measured when increasing the numbers of VMS on unit distance and the size of characters. The size of character was almost not effected in similar to the result of stress index and the satisfaction level increased when increasing the number of VMS on the unit distance. The results of this research can be utilized as basic data for the ITS system design and operation stages.

• Journal of Korean Society of Transportation
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• v.35 no.2
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• pp.116-128
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• 2017

Traffic accidents can be defined as a physical collision event of vehicles occurred instantaneously when drivers do not perceive the surrounding vehicles and roadway environments properly. Therefore, detecting the high potential events that cause traffic accidents with monitoring the interactions among the surroundings continuously by driver is the prerequisite for prevention the traffic accidents. For the analysis, basic data were collected to analyze interactions using a test vehicle which is equipped the GPS(Global Positioning System)-IMU(Inertial Measurement Unit), camera, radar and RiDAR. From the collected data, highway geometric information and the surrounding traffic situation were analyzed and then safety evaluation algorithm for driving vehicle was developed. In order to detect a dangerous event of interaction with surrounding vehicles, locations and speed data of surrounding vehicles acquired from the radar sensor were used. Using the collected data, the tangent and curve section were divided and the driving safety evaluation algorithm which is considered the highway geometric characteristic were developed. This study also proposed an algorithm that can assess the possibility of collision against surrounding vehicles considering the characteristics of geometric road structure. The methodology proposed in this study is expected to be utilized in the fields of autonomous vehicles in the future since this methodology can assess the driving safety using collectible data from vehicle's sensors.