• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.8
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• pp.2666-2687
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• 2022

As a new alternative communication scheme in 5G, unmanned aerial vehicle (UAV) is used as a relay in the remote base station (BS) for assistant communication. In order to ameliorate the quality of the backhaul link, a UAV backhaul transmission scheme based on improved Nash equilibrium (NE) strategy is proposed. First, the capacity of air-to-ground (A2G) channel by the link preprocess is maximized. Then, the maximum utility function of each UAV is used as the basis of obtaining NE point according to the backhaul channel and the backhaul congestion. Finally, the improved NE strategy is applied in multiple iterations until maximum utility functions of all the UAVs are reached, and the UAVs which are rejected by air-to-air (A2A) link during the process would participate in the source recovery process to construct a multi-hop backhaul network. Simulation results show that average effective backhaul rate, minimum effective backhaul rate increases by 10%, 28.5% respectively in ideal A2G channel, and 11.8%, 42.3% respectively in fading channel, comparing to pure NE strategy. And the average number of iterations is decreased by 5%.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.4
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• pp.1-9
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• 2015

Since logical ground and method to deduct location to install Integrated Standard Controller under development to combine physically and functionally multiple enclosures of controllers for various ITS equipments on streets into one enclosure, there are much difficulty to apply it to site. Particularly we need to establish standardized methodology to deduct optimal location to integrate individual controllers installed dispersedly on streets such as node part and line part. Accordingly this study has the purpose of suggesting more reasonable and efficient methodology to determine location for Integrated Standard Controller to be developed newly. For this, new solution has been searched by using centroid which is utilized to decide facility location in urban planning. As the result of analysis, central point among centroid, in which equal connection to each equipment is possible is proved to be the most reasonable and correct coordinate and zone is proposed as installation location through designating coordinate system. The methodology suggested by this study seems to have high degree of utilization in site according to expansion of integrated standard controller market.

• Korean Journal of Applied Biomechanics
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• v.27 no.2
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• pp.141-147
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• 2017

Objective: We obtained force-displacement curves for countermovement jumps of multiple heights and examined the effect of an arm swing on changes in vertical jumping strategy. Countermovement jumps with hands on hips (Condition 1) and with an arm swing (Condition 2) were evaluated to investigate the mechanical effect of the arm movement on standing vertical jumps. We hypothesized that the ground reaction force (GRF) and/or center of mass (CoM) motion resulting from the countermovement action would significantly change depending on the use of an arm swing. Method: Eight healthy young subjects jumped straight up to five different levels ranging from approximately 10% (~25 cm) to 35% (~55 cm) of their body heights. Each subject performed five sets of jumps to five randomly ordered vertical elevations in each condition. For comparison of the two jumping strategies, the characteristics of the boundary point on the force-displacement curve, corresponding to the vertical GRF and the CoM displacement at the end of the countermovement action, were investigated to understand the role of arm movement. Results: Based on the comparison between the two conditions (with and without an arm swing), the subjects were grouped into type A and type B depending on the change observed in the boundary point across the five different jump heights. For both types (type A and type B) of vertical jumps, the initial vertical force at the start of push-off significantly changed when the subjects employed arm movement. Conclusion: The findings may imply that the jumping strategy does change with the inclusion of an arm swing, predominantly to modulate the vertical force advantage (i.e., the difference between the vertical force at the start of push-off and the body weight).

• Journal of IKEEE
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• v.22 no.1
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• pp.127-135
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• 2018

This paper was studied the tri-band folded monopole antenna design with Mu-negative metamaterial unit cell, which operates at 700 MHz UHD broadcast band and 2.45 GHz/5 GHz WiFi band. The MNR metamaterial is fabricated by forming a capacitor on the backside of the antenna substrate and connecting it to the ground plane through a strip line and a via hole so that a single cell can operate in the MZR (Mu zero resonator). Through this, the resonance point can be controlled to resonate in the zero mode in 700 MHz band, and the bandwidth is improved. Experimental results show that the 10dB bandwidth and gain are 309 MHz (41.2%) and 5.298 dB at the first resonance point, and the 10dB bandwidth and gain at the second resonance point are 821.9 MHz (33.5%) and 2.7840 dB respectively. At the third resonance point, the gain and bandwidth were 1.1314 GHz (20.6%) and 2.9484 dB respectively. We confirmed that the resonance point with theoretical value is in agreement with experimental value. And the radiation pattern is generally omnidirectional, and it has been confirmed that the radiation pattern is good in both forward and backward directions at 0.75 GHz and 2.45 GHz, and has a radiation pattern with multiple lobes at 5.5 GHz.

• Journal of the Korea Society of Computer and Information
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• v.25 no.6
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• pp.9-15
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• 2020

In this paper, we propose a case that drone (unmanned aerial vehicle), one of the representative technologies of the 4th Industrial Revolution, threatens airport safety and privacy infringement, and describes a drone control system proposal to solve the problem. Unmanned aerial vehicle (Drone) is creating a serious problem recently, In Korea, on May 21, 19, according to the Jeju Regional Aviation Administration, drones flew over Jeju Jeongseok Airfield twice in the same month, causing problems in aircraft operation. In overseas cases, two drones near the runway of Gatwick International Airport in the UK There has been a disturbance in which the takeoff and landing of the aircraft flies for a while, and various problems have occurred, such as voyeuring the private life of an individual using a drone. This paper is equipped with an Acess Point transponder mounted on a drone (unmanned aerial vehicle), and unspecified many who want to receive flight information (coordinates, altitude, and obstacles) of the drone access the drone AP, receive and receive the flight information of the drone, and receive unspecified multiple Drone AP flight information is collected and collected to provide the information of the drone currently floating on one user interface screen. In addition, an AP transponder is proposed to operate a safe drone (unmanned aerial vehicle) and the drone's flight information is transmitted., To receive and collect and collect data.

• Journal of the Korea Society for Simulation
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• v.29 no.1
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• pp.47-55
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• 2020

This paper presents a real-time autonomous computation of shot numbers and aiming points against multiple soft targets on grounds by applying an unsupervised learning, k-mean clustering and Monte carlo simulation. For this computation, a 100 × 200 square meters size of virtual battlefield is created where an augmented enemy infantry platoon unit attacks, defences, and is scatted, and a virtual weapon with a lethal range of 15m is modeled. In order to determine damage types of the enemy unit: no damage, light wound, heavy wound and death, Monte carlo simulation is performed to apply the Carlton damage function for the damage effect of the soft targets. In addition, in order to achieve the damage effectiveness of the enemy units in line with the commander's intention, the optimal shot numbers and aiming point locations are calculated in less than 0.4 seconds by applying the k-mean clustering and repetitive Monte carlo simulation. It is hoped that this study will help to develop a system that reduces the decision time for 'detection-decision-shoot' process in battalion-scaled combat units operating Dronebot combat system.

• Journal of Advanced Navigation Technology
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• v.26 no.6
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• pp.427-433
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• 2022

Obstacle detection, collision recognition, and avoidance technologies are required the collision avoidance technology for UAVs. In this paper, considering collinear multiple static obstacle, we propose an obstacle detection algorithm using LiDAR and a collision recognition and avoidance algorithm based on CPA. Preprocessing is performed to remove the ground from the LiDAR measurement data before obstacle detection. And we detect and classify obstacles in the preprocessed data using the K-means clustering algorithm. Also, we estimate the absolute positions of detected obstacles using relative navigation and correct the estimated positions using a low-pass filter. For collision avoidance with the detected multiple static obstacle, we use a collision recognition and avoidance algorithm based on CPA. Information of obstacles to be avoided is updated using distance between each obstacle, and collision recognition and avoidance are performed through the updated obstacles information. Finally, through obstacle location estimation, collision recognition, and collision avoidance result analysis in the Gazebo simulation environment, we verified that collision avoidance is performed successfully.

• Journal of Fashion Business
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• v.16 no.1
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• pp.83-102
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• 2012

The instant trend of mobile functionality in the digital age is performing a mediating role of promoting the hybrid tendency in fashion and cosmetics industry. Consumers' needs, which are getting complex and diversified along with development in scientific technology, are requiring product of technology equipped with multi-tasking function in the whole industry. The social and cultural factors, which are shown in cosmetics due to the instant trend of mobile functionality, came to be known on the basis of a ground for classification caused by a change in nomadic lifestyle and by the advance in scientific technology. The irst, The mobile functionality, which is being developed in fashion in the digital age, was indicated to be types such as mobility, one-off, and unity. Second, Even the types of mobile functionality, which are also being developed in make-up and cosmetics in digital age, were indicated to be mobility, one-off, and unity. Third, The trend caused by mobile functionality in fashion was consistent with a type in mobile functionality, which is being developed in cosmetics, thereby having been indicated to be the same type. This implies that there is the same type through independent trend in each sphere even while fashion and cosmetics organically function in the middle of the whole frame, which expresses a human being's external beauty, and implies that even the cosmetics are influenced by fashion. Swift-type beauty product, which is thrown away within one week lengthily and after being used once, are being launched diversely. This quick product can be said to be product that best reflected the characteristic of digital age. However, at this point of time that fast fashion and instant cosmetics, which are thrown away in the wake of being worn easily, are overflowing, the clothing and product with perfection, which has philosophy and thinking of being put more devotion, exert more value and are felt to be necessary.

• Journal of the Korean earth science society
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• v.39 no.5
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• pp.403-418
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• 2018

This study conducted synoptic and mesoscale analyses to understand the cause of Japan Tsukuba tornado development, which occurred at 0340 UTC 6 May 2012. Prior to the tornado occurrence, there was a circular jet stream over Japan, and the surface was moist due to overnight precipitation. The circular jet stream brought cold and dry air to the upper-level atmosphere which let strong solar radiation heat the ground with clearing of sky cover. A tornadic supercell developed in the area of potentially unstable atmosphere. Sounding data at Tateno showed a capping inversion at 900 hPa at 0000 UTC 6 May. Strong insolation in early morning hours and removal of the inversion instigated vigorous updraft with rotation due to vertical shear in the upper-level atmosphere. This caused multiple tornadoes to occur from 0220 to 0340 UTC 6 May 2012. When comparing Tateno's climatological temperature and dew-point temperature profile on the day of event, the mid-level atmosphere was moister than typical sounding in the region. This study showed that tornado development in Tsukuba was caused by a combination of (a) topography and potential vorticity anomaly, which increased vorticity over the Kanto Plain; (b) vertical shear, which produced horizontal vortex line; and c) thermal instability, which triggered supercell and tilted the vortex line in the vertical.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.6
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• pp.457-465
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• 2014

This paper introduces a test bed for communication protocol schemes of underwater acoustic sensor network, and also shows experimental results obtained from the test bed. As a testing protocol, carrier sense multiple access/collision avoidance (CSMA/CA) is evaluated on underwater acoustic channel. A sensor node is equipped with a DSP control board of ATmega2560 and a commercial underwater modem produced by Benthos. The control board not only manipulates a GPS signal to acquire the information of location and time, but also controls the underwater modem to operate according to the procedure designed for a given testing protocol. Whenever any event takes place such as exchanging control/data packets between underwater modems and acquiring location and timing information, each sensor node reports them through radio frequency (RF) air interface to a central station located on the ground. The four kinds of packets for CSMA/CA, RTS(Request To Send), CTS(Clear to Send), DATA, ACK(Acknowledgement) are designed according to the underwater communication environment and are analyzed through the lake experiment from the point of feasibility of CSMA/CA in underwater acoustic communications.