• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1081-1083
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• 2003

In this paper, a new speed sensorless induction motor scheme which can work at any speed including the zero speed is presented. The proposed method is robust to secondary resistance variations. Simultaneous estimation of speed and secondary resistance are realized based on a feedforward type torque control scheme. The secondary flux with a low frequency sinusoidal waveform is used to help the estimation. Simulations results supported by experiments are given to show the effectiveness of this method.

• Korean Journal of Human Ecology
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• v.12 no.5
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• pp.669-685
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• 2003

This research examined the work performance by consumer counselors, evaluations of their counseling work, the level of their satisfaction, and willingness to sustain consumer counseling work among Consumer Agencies and also identified the variables influencing the evaluation scores on those. The results were summarized as follows. First, the evaluation scores on the work performance of consumer counseling were generally high and they turned out to be generally satisfied with their work. On the other hand, most counselors responded that they would continue their counseling work. Second, there were differences in evaluation scores about speed and specialized area of counseling among Consumer Agencies. Counselors who worked for the Korea Consumer Protection Board recorded high scores in those both criteria. There were differences in the willingness of counselors to continue their counseling work among Consumer Agencies, too. Third, the evaluation scores in six areas of counseling tasks were high when the degree of satisfaction of counselors were high or when agencies treated the counseling important. Fourth, when counselors earned more salaries and owned the experience of in-firm training and when the Consumer Agencies highly valued counseling as consumer tasks, the degree of satisfaction among counselors increased. Finally, when counselors were old, major in consumer science, and held regular work-schedule, they exhibited high degree of satisfaction in their counseling work and they showed greater willingness to sustain their counseling work.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.4
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• pp.561-571
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• 2019

Drilling and charging of the blast holes during NATM tunneling works take more than 30% of construction time among the whole tunneling work process. Prediction of ground condition ahead of tunnel face has been studied by several researchers by correlating percussion pressure and drilling speed during tunneling work with the ground condition and/or RMR values. However, most of the previous researches were conducted in the granite rock condition which is the most representative igneous rock in the Korean peninsula. In this study, drilling speeds in igneous rocks were analyzed and compared with those in sedimentary rocks (most dominantly composed of conglomerates, sandstones, and shales) under the similar RMR ranges; it was identified that the drilling speed is pretty much affected by rock types even in a similar RMR range. Under the similar RMR values, the drilling speed was faster in sedimentary rocks compared with that in igneous rock. Moreover, while the drilling speed was not much affected by change of the RMR values in igneous rocks, it became faster in sedimentary rocks as the RMR values got lower.

• Journal of Korean Society of Transportation
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• v.34 no.6
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• pp.535-547
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• 2016

This study aims to identify factors that affect the degree of injury severity sustained in traffic crashes on work zone of Korean expressways. To this end, decision tree method was applied to identify influential factors on injury severity and compare characteristics of those factors between work zone and non-work zone. The results from the comparison show that the risk of severity was low when traffic volume and heavy vehicle ratio are high because the factors lower the overall section speed. On the other hand, when the traffic volume and the heavy vehicle ratio are low, the section speed increased and the tendency for high injury severity was confirmed. These findings are expected to help transportation planners and engineers understand which risk factors contribute more to severe injury in the work zones such that they can effectively prepare and implement safety countermeasures.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.03a
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• pp.132-136
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• 1996

A Study is a experiment which is figure out to aptimum discharge cutting condition of the surfaceroughness, electric discharging speed and electro wear ratio with Ton Toff and V(voltage) as an input condition according to the current(Ip) in an electric spark machine ; 1)Electrode is utilized Cu(coper) and Graphite. 2)Work piece is used the material of carbon steel. The condition of experiment is; 1)Current is varied 0.7(A) to 50(A). 2)Pulse time(Ton) is varied 3($\mu$s) to 240($\mu$s) and also Toff is varied 7($\mu$s) to 20($\mu$s). 3)The time of electric discharging to work piece in each time is 30(min) to 60(min) 4)After the upper side of work piece was measured in radius (5${\mu}{\textrm}{m}$) of syulus analyzed the surface roughness to made the table and graph of Rmax by yielding data. 5)Electro wear ratio is; \circled1Coper was measured cx-machining and post machining but the electronic baiance. \circled2The ex-machining of graphite measured by it, the post-machining was found the data from volume specific gravity and analyzed to made its table and graph on ground the data 6)In order to keep the accuracy of voltage affected to the work piece was equipped with the A.V.R(Automatic Voltage Regulator). 7)The memory scope was sticked to the electric spark machine. 8)In order to preserve the precision of current, to get rid of the noise occured by internal resistance of electric spark machine and to force injecting for the discharge fluid, it made the fixed table for a work piece to minimize the work error by means of one's failure during the electric discharging According to above results, the surface roughness by the variation of electrodw and current was analyzed to compare KS(Korea Standards) It was decided the optimum condition of electric discharge cutting through analyzing the effect of electric discharge speed and electro wear ratio.

• Journal of Korea Society of Industrial Information Systems
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• v.18 no.6
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• pp.61-70
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• 2013

This paper proposes a design of SARPE(Speed and Azimuth based Routing Protocol for Emergency) system which transfers an emergency message rapidly and accurately by minimizing path disconnection with a vehicle's speed and azimuth in case of accidents. The SARPE system accomplishes the path search based on an azimuth in order to minimize unnecessary messages and workload. It also selects the paths with the lowest probability that the path disconnection will happen by using the difference between the speed(maximum, minimum) of intermediate nodes and the average speed of a source node and destination node. Therefore, this paper minimizes the path resetting work happening due to path disconnection and transfers an emergency message rapidly and accurately.

• Journal of the Korean Society for Railway
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• v.10 no.3 s.40
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• pp.257-263
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• 2007

The critical speed above which the vehicle become unstable is one of the items that should be verified in the development of a new train. In the case of a high speed tilting train, which requires both higher critical speed and higher curving speed, the critical speed should be more carefully treated because the both requirements are in conflict with each other in the conventional train design. The main purpose of the present work is to estimate the linear and non-linear critical speeds of 200km/h Korean Tilting Train 'Hanbit200' under development. The newly developed self-steering mechanism was attached to the tilting train to ensure that the critical speed falls under the lower yaw stiffness which is needed to secure higher curving performance. The simulation for predicting the critical speed was done by a commercially available vehicle dynamics software. A full scale roller rig test was carried out to validate the numerical results and to verify the effectiveness of the self-steering mechanism.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.6
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• pp.29-35
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• 2010

Recently the industry high-speed machining has been applied to the automotive, aircraft, electronics parts machining because the effect of cost savings, machining time reduction and productivity improvement. In this study recently the aircraft structural aluminum alloy 7075 used in cutting the ball end-mill on the surface roughness terms most affect the parameters of the spindle speed and feed rate on the surface roughness of the work-piece according to the cutting depth is to investigate. Cutting depth at 0.3 mm has the lowest surface roughness.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.4
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• pp.212-220
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• 2004

The present DC Motor or STEP Motor have been used in electronic work and products. There are many papers that let those Motor improved more conveniently in controlling and measuring those than before. By controlling and measuring those, the convenience of users and the functions of products can be improved. In addition, the responding speed of whole system can be increased by improving it of controlling and measuring. Therefore it is necessary that we develop motor motion application. Because of this necessity, neural networks was used to improve the responding speed of controlling and measuring, and a new application was developed for the convenience of users. This paper showed that efficiency of controlling methodology by neural-network is superior to others in correctness and speed. We are intend to verify its practical usefulness though experimentations.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.47-56
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• 1999

New rolling speed prediction model has been developed for the precise presetting rolling speed of each finishing mill stand in the tandem hot strip mill. Those factors such as neutral point, work roll diameter, rolling torque, friction coefficient, bite angle and the thickness at each side of entry and deliver of the rolls were taken into account. To consider width effect on forward slip, calibration factors obtained from rolling torque has been added to new prediction model and refining method has also been developed to reduce the speed unbalance between adjacent stands. The application of the new model showed a good agreement in rolling speeds between the predictions and the actual measurements, and the standard deviation of prediction error has also been significantly reduced.