• Journal of Environmental Science International
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• v.26 no.9
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• pp.1013-1021
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• 2017

Exposure to Diesel Particulate Matter (DPM) potentially causes adverse health effects (e.g. respiratory symptoms, lung cancer). Due to a lack of data on Elemental Carbon (EC) exposure levels in underground copper ore mining (unlike other underground mining industries such as non-metallic and coal mining), this case study aims to provide individual miners' EC exposure levels, and information on their work practices including use of personal protective equipment. EC measurement was carried out during different work activities (i.e. drilling, driving a loader, plant fitting, plant operation, driving a Specialized Mining Vehicle (SMV)) as per NIOSH Method 5040. The copper miners were working 10 h/day and 5 days/week. This study found that the most significant exposures to EC were reported from driving a loader (range $0.02-0.42mg/m^3$). Even though there were control systems (i.e. water tanks and DPM filters) on the diesel vehicles, around 49.5% of the results were over the adjusted recommendable exposure limit ($0.078mg/m^3$). This was probably due to: (1) driver's frequently getting in and out of the diesel vehicles and opening the windows of the diesel vehicles, and (2) inappropriate maintenance of the diesel vehicles and the DPM control systems. The use of the P2 type respirator provided was less than 19.2%. However, there was no significant difference between the day shift results and the night shift results. In order to prevent or minimize exposure to EC in the copper ore mine, it is recommended that the miners are educated in the need to wear the appropriate respirator provided during their work shifts, and to maintain the diesel engine and emission control systems on a regular basis. Consideration should be given to a specific examination of the diesel vehicles' air-conditioning filters and the air ventilation system to control excessive airborne contaminants in the underground copper mine.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.813-820
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• 2010

The vertical roller mill is important for machine grinding and mixing various crude materials in the process of producing Portland cement. A vertical roller mill is subjected to cyclic bending stress because of the roller load. Because of the cyclic bending stress, only $4{\times}10^6-8{\times}10^6$ cycles are achieved instead of $4{\times}10^7$ cycles. The stress also causes fractures at the edge of grinding path of the outer roller. The expenses incurred in repairing the grinding path amounts to 30% of the total maintenance cost. Therefore, it is desirable to redesign the vertical roller mill in order to reduce the expenses incurred in repairing the roller. In this study, artificial neural networks (ANNs) were applied in order to solve the multiobjective optimization problem for vertical roller mills by using the function approximation ability of ANNs. To learn and generalize ANNs, the maximum and minimum stresses were estimated from the results of the finite-element analysis of a vertical roller mill. Thus, ANNs could be applied to solve the multiobjective optimization problem.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.7
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• pp.1056-1063
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• 2015

In this paper, we develop an interface for aerial photograph platform which consists of a quadrotor and a gimbal using the human body and the head posture. As quadrotors have been widely adopted in many industries such as aerial photography, remote surveillance, and maintenance of infrastructures, the demand of aerial video and photograph has been increasing remarkably. Stick type remote controllers are widely used to control a quadrotor, but this method is not an intuitive way of controlling the aerial vehicle and the camera simultaneously. Therefore, a new interface which controls the serial photograph platform is presented. The presented interface uses the human head movement measured by head-mounted display as a reference for controlling the camera angle, and the human body posture measured from Kinect for controlling the attitude of the quadrotor. As the image captured by the camera is displayed on the head-mounted display simultaneously, the user can feel flying experience and intuitively control the quadrotor and the camera. Finally, the performance of the developed system shown to verify the effectiveness and superiority of the presented interface.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.4
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• pp.255-262
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• 2016

There has been intense research on self-diagnosis systems in railway applications, since stability and reliability have become more and more significant issues. Wired sensors have been widely used in the railway vehicles, but because of the difficulty in their maintenance and accessibility, they ar not considered for self-diagnosis systems. To have a self-monitoring system, wireless data transmission and self-powered sensors are required. For this purpose, a thermoelectric energy harvesting module that can generate electricity from temperature gradient between the bogie axle box and ambient environment was introduced in this work. The temperature gradient was measured under actual operation conditions, and the behavior of the thermoelectric module with an external load resistance and booster circuits was studied. The proposed energy harvesting system can be applied for wireless sensor nodes in railroad vehicles with optimization of thermal management.

• Journal of Korean Society of Transportation
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• v.31 no.2
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• pp.80-89
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• 2013

The purpose of this research is to optimize the line planning of the intercity passenger railway. In this study, the line planning problem has been formulated into a mixed integer programming by minimizing both user costs (passenger's total travel time) and operator costs (operation, maintenance and vehicle costs) with multiple train types. As a solution algorithm, the branch-and-bound method is used to solve this problem. The change of travel demand, train speed and the number of schedules have been tested through sensitivity analysis. The optimal stop-schedules and frequency as well as system split with respect to each train type have been found in the case study of Kyoung-bu railway line in Korea. The model and results of this research are useful to make a decision for railway operation strategy, to analyze the efficiency of new railway systems and to evaluate the social costs of users and operators.

• Journal of the Korean Society of Safety
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• v.21 no.2 s.74
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• pp.15-21
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• 2006

The railroad bogie's components experience repeated loading during service. Especially, oil damper bush has been fatigue fractured on the plane between rubber and steel stem during service, and which results in inferior of performance of the bogie. In this study, in order to offer a proper maintenance method of the bush, bubber bush used for the oil damper was fatigue tested and its damage fraction during service was estimated. Also, FEM analysis on the bush was conducted. When 1400, 1200, and 1000kgf of repeated loads were applied to the oil damper bush, final damage fraction exhibited 63.7%, 50% and 40%. From the results of FEM analysis, deformation energy density was found to be $0.5452kgf/mm^{2}$ at an applied load of 1400kgf and the location with maximum value coincided with the fractured location of the bush. Finally, it will be desirable to adopt the normalized damage fraction rather than absolute damage fraction in estimating remaining service lifetime of the bush.

• YAKHAK HOEJI
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• v.33 no.6
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• pp.333-338
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• 1989

It has been postulated that abnormal characteristics of central noradrenergic nervous system has been implicated in the development and maintenance of hypertension in several modes of experimental hypertension including spontaneously hypertensive rats (SHR). In the present study, we attempt to determine if abnormal characteristics of central noradrenergic nervous system in SHR is caused by genetic factors or hypertensive phenomena by evaluating the changes of central adrenoceptors after long-term treatment of clonidine. Animals were divided into three groups; (1) 14 week-old SHR; (2) age-matched normotensive Wistar rats (NW); (3) DOCA-Salt induced hypertensive rats (DS). Clonidine (100 ug/kg) or vehicle was injected intraperitonealy twice a day for 15 days. Changes of ${\alpha}_1-$ and ${\alpha}_2-receptor$ desities following clonidine treatment were determiend in frontal corte, medulla oblongata and hypothalamus using 3H-WB4101 and 3H-clonidine, respectively. Densities of ${\alpha}_1$ and ${\alpha}_2-receptors$ following clonidine treatment were not changed in frontal cortex and medulla oblongate of SHR as well as DS, but increased in frontal cortex of NW and decreased in medulla oblongata of NW. On the other hand, densities of ${\alpha}_1-receptors$ were increased and densities of ${\alpha}_2-receptors$ were not changed in hypothalamus of SHR but densities of ${\alpha}_1-$ and ${\alpha}_2-receptors$ were decreased in hypothalamus of DS as well as NW. These results suggest that such differences in frontal cortex and medulla oblongata of SHR may be results of hypertensive phenomena whereas those in hypothalamus may be relevant to genetic factors of SHR.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.6
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• pp.1567-1572
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• 2012

An IPC(instrument panel Cluster) is a useful device that provides driving information to the driver. The information includes the vehicle speed, RPM, mileage, etc. The traditional IPC has been mostly implemented with mechanical technique. According to increment of needs for the convenience of IPC by user, the IPC must provide graphical interface and efficient driving information. Also the user-friendly IPC is needed by drivers. Thus flexible and robust software structure and development methods are required in order to develop IPC. In this paper, we propose software architecture and design method for the IPC using modeling method. We use MVC model and UML to model software architecture because they have flexible and robust characteristics. We can develop the various forms of information screen by separating views from model by using state diagram and class diagram in UML. Through this, the cost saving and ease of maintenance can be expected. The development time and cost can be reduced by using proposed method.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.6
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• pp.1321-1326
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• 2012

An IPC(instrument panel Cluster) is a useful device that provides driving information to the driver. The information includes the vehicle speed, RPM, mileage, etc. The traditional IPC has been mostly implemented with mechanical technique. According to increment of needs for the convenience of IPC by user, the IPC must provide graphical interface and efficient driving information. Also the user-friendly IPC is needed by drivers. Thus flexible and robust software structure and development methods are required in order to develop IPC. In this paper, we propose software architecture and design method for the IPC using modeling method. We use MVC model and UML to model software architecture because they have flexible and robust characteristics. We can develop the various forms of information screen by separating views from model by using state diagram and class diagram in UML. Through this, the cost saving and ease of maintenance can be expected. The development time and cost can be reduced by using proposed method.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.6
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• pp.1479-1485
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• 2012

The parking management system can increase driver's convenience with detailed parking information service in the parking lot. At the same time, parking management system consumes non-negligible electrical energy with large amount of sensors, displays and control modules. With the increase in the demand for green and sustainable building design all over the world, it becomes a meaningful issue for parking management system to reduce operating power. This paper presents the preliminary design and estimated results of a parking management system which is optimized to reduce the power consumption mainly on detectors and displays. The system design is based on pre-developed wireless parking detectors, Park Tile and Park Disk. The system has a number of parking space detectors, vehicle count detectors, information displays, guidance terminals and other control units. We have performed system architecture design, communication network design, parking information service scenario planning, battery life regulation and at last operating power estimation. The estimated operating power was 0.93KW per parking-slot, which is 20% of traditional systems. The estimated annual maintenance cost was 18% of traditional systems.