• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1240-1246
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• 2006

Generally, there are two types of main factors to affect output power quality of a auxiliary power supply an EMU(electric multiple unit). One is a voltage flicker by amplitude modulation of short time and air compressors. The other is repetitive motion of large capacity motor such as air compressors, HVAC unit etc. in main factors. This paper compared two kinds of fluorescent lamp, 32W (after remodeling interior) and 40W(before remodeling interior) and measured the light output varying input power(AC220V) for a flicker phenomenon related power supply of lamps in EMU. Also, we analyzed a flicker considering EMU operating time and density in order to grasp main factors of a load change to cause a voltage change. As a results of test, a 40W fluorescent lamp was more insensitive with 20.26% degree an eye recognition degree sides about changes of the input power and lower with 19.9% voltage side generating flicker compare with fluorescent lamp 32W. Also, we confirmed the fact which the fluorescent lamp flicker was generated by varying fluorescent lamp output voltage when the commercial EMU was in high driving density and at the busy time. Additionally, we confirmed the frequency band which an EMU passenger could feel sensitively blinking of a fluorescent lamp was visually $8Hz{\sim}15Hz$.

• Journal of the Korean GEO-environmental Society
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• v.12 no.3
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• pp.55-61
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• 2011

Song-Do international city is the area developed in large-scale land reclamation. Song-Do area consists of reclamation layer, sedimentary layer(loose silt, soft clay and sand alternating) and residual layer from the ground surface. Therefore, using pile foundation is inevitable to build structures safely. In this area, driven PHC piles have been generally constructed in terms of environmental and economic conditions. As a result of analyzing 4 sites in Song-Do district 5 and 7 recently, the method of driving pile has many problems because of existence of rigid soil in sedimentary layer and installation of more than 30m piles. In this case, when installing piles by drive after pre-boring up to appropriate depth, the results of constructability analysis were very good. And in the economic efficiency, although 4% of construction cost rose, it was a very slight increase in comparison with improvement of workability. In the case of the stability, more than 70% compared to the allowable stress of piles was satisfied through the load test. As a result, when PHC piles is installed in Song-Do district, the proper construction method is that piles are located at bearing layer after boring rigid sand layer.

• Journal of the Korean Geotechnical Society
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• v.22 no.6
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• pp.15-26
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• 2006

Although numerous investigations have been performed over the years to predict the behavior and bearing capacity of piles, the mechanisms are not yet entirely understood. The prediction of bearing capacity is a difficult task, because large numbers of factors affect the capacity and also have complex relationship one another. Therefore, it is extremely difficult to search the essential factors among many factors, which are related with ground condition, pile type, driving condition and others, and then appropriately consider complicated relationship among the searched factors. The present paper describes the application of Artificial Neural Network (ANN) in predicting the capacity including its components at the tip and along the shaft from dynamic load test of the driven piles. Firstly, the effect of each factor on the value of bearing capacity is investigated on the basis of sensitivity analysis using ANN modeling. Secondly, the authors use the design methodology composed of ANN and genetic algorithm (GA) to find optimal neural network model to predict the bearing capacity. The authors allow this methodology to find the appropriate combination of input parameters, the number of hidden units and the transfer structure among the input, the hidden and the out layers. The results of this study indicate that the neural network model serves as a reliable and simple predictive tool for the bearing capacity of driven piles.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.715-720
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• 2023

The military is driving innovative changes such as AI, cloud computing, and drone operation through the Fourth Industrial Revolution. It is expected that such changes will lead to a rapid increase in the demand for information exchange requirements, reaching all lower-ranking soldiers, as networking based on IoT occurs. The flow of such information must ensure efficient information distribution through various infrastructures such as ground networks, stationary satellites, and low-earth orbit small communication satellites, and the demand for information exchange that is distributed through them must be appropriately dispersed. In this study, we redefined the DSCP, which is closely related to QoS (Quality of Service) in information dissemination, into 11 categories and performed research to map each cluster group identified by cluster analysis to the defense "information exchange requirement list" on a one-to-one basis. The purpose of the research is to ensure efficient information dissemination within a multi-layer integrated network (ground network, stationary satellite network, low-earth orbit small communication satellite network) with limited bandwidth by re-establishing QoS policies that prioritize important information exchange requirements so that they are routed in priority. In this paper, we evaluated how well the information exchange requirement lists classified by cluster analysis were assigned to DSCP through M&S, and confirmed that reclassifying DSCP can lead to more efficient information distribution in a network environment with limited bandwidth.

• Journal of agriculture & life science
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• v.45 no.5
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• pp.105-113
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• 2011

This study was carried out to develop an automatic loading equipment that can load seedling trays on loading position of the seedling bed driving on enclosed-type rail installed for interconnecting each process of raising seedlings in plant factory. The experiment of transferring the seedling tray by monorail pusher was carried out to figure out the required transfer force and problems during push type device of transporting the plastic seedling trays, that has completed its sowing process, which are installed onto the board of different materials. From the results of this experiment, the loading equipment which can exactly load three of the seedling trays orderly on the loading position of the seedling bed was designed and made. When three sowed trays on every board are transferred by pusher with the speed is at 30 cm/s, the maximum peak transfer force with maximum overshooting at initial transient state and the maximum transfer force at stead state are were respectively 32.8 N, 29.4 N on rubber board, 29.7 N, 22.5 N on a wooden board, 26.9 N, 19.6 N on a acrylic board, and 27.6 N, 19.1 N on an iron board. Changes in the transfer force occurred its maximum at the moment when the pusher collided with the tray, after the collision gradually decreased until it became stable. When two or three trays placed it in order of widthwise are transferred, it is occurred the overlapping of the tray's external bracket. The developed automatic loading equipment with PLC controller did not make any operation error through 100 times of tests, its maximum seedling tray loading speed was 2 sec/tray and its maximum error of transferred location of the tray was 0.5 cm.

• Land and Housing Review
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• v.7 no.4
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• pp.307-314
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• 2016

Energy harvesting technique is to utilize energy that is always present but wasted. In this study, we have developed the energy harvester of the hybrid method utilizing both vibration and pressure of the vehicle traveling a road or parking lot. In the previous study, we have developed a prototype energy harvester, improved hybrid energy harvester, and developed a final product that offers improved performance in the hybrid module. The results were published in the previous paper. In this study, we installed the finally developed hybrid module in the actual parking lot. And we measured the power generation performance due to pressure and vibration, and the running speed of the vehicle when the vehicle is traveling. And we compared the results with those obtained in laboratory conditions. In a previous study performed in laboratory conditions the maximum power of the energy block was 1.066W when one single time of vibration, and 1.830W when succession with 5 times. On the other hand, in this study, we obtained the average power output of 0.310W when the vehicle is running at an average 5 km/h, 0.670W when at an average 10 km/h, and 1.250W when at an average 20 km/h, and 2.160W when at an average 5 km/h. That is, the higher the running speed of the vehicle has increased power generation performance. However, when compared to laboratory conditions, the power generation performance of the energy block in driving speed by 20km/h was lower than those in laboratory conditions. In addition, when compared to one time of vibration of laboratory conditions, power generation performance was higher when the running speed 20km/h or more and when five consecutive times in laboratory conditions, it was higher when the running speed 30km/h or more. It could be caused by a difference of load conditions between the laboratory and the actual vehicle. Thus, applying the energy block on the road would be more effective than that on the parking lot.