• Journal of IKEEE
• /
• v.22 no.2
• /
• pp.309-315
• /
• 2018

A Stepped Frequency Radar(SFR) is a method of achieving high range resolution by gradually increasing the frequency of a transmitted pulse to create a wide synthetic bandwidth. However, in the case of moving target, accurate range estimation can not be performed due to the range-Doppler coupling phenomenon, so it is necessary to compensate through accurate velocity estimation. In this paper, we propose a stepped frequency radar waveform with a Coherent Pulse Train(CPT), velocity estimation results according to parameters using this method and VMD(Velocity Measurement Data) were compared and analyzed by numerical simulations.

• Journal of Digital Contents Society
• /
• v.13 no.3
• /
• pp.451-457
• /
• 2012

Recently, as the use of real time traffic information of a car navigation system increases rapidly with the development of Intelligent Transportation Systems (ITS), path search is getting more important. Previous algorithms, however, are mostly for the shortest distance searching and provide route information using static distance and time information. Thus they could not provide the most optimal route at the moment which changes dynamically according to traffic. Accordingly, in this study, Semantic Shortest Path algorithm with Reduction ratio & Distance(SSP_RD) is proposed to solve this problem. Additionally, a routing model based on velocity reduction ratio and distance and a dynamic route link map are proposed.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.9 no.4
• /
• pp.782-791
• /
• 2005

In this paper, path planning and tracking problems are mentioned to guarantee efficient and safe navigation of autonomous mobile robots. We focus on the path planning and also deal with the path tracking and obstacle avoidance. We improved the conventional distance transform (DT) algorithm for the path planning. Using the improved DT algorithm, we obtain paths with shorter distances compared to the conventional DT algorithm. In the stage of the Path tracking, we employ the fuzzy logic controller to conduct the path tracking behavior and obstacle avoidance behavior. Through computer simulation studies, we show the effectiveness of the Nosed navigational algorithm for autonomous mobile robots.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• v.9 no.1
• /
• pp.295-299
• /
• 2005

In this paper, path planning and tracking problems are mentioned to guarantee efficient and safe navigation of autonomous mobile robots. We focus on the path planning and also deal with the path tracking and obstacle avoidance. We improved the conventional distance transform (DT) algorithm for the path planning. Using the improved DT algorithm, we obtain paths with shorter distances compared to the conventional DT algorithm. In the stage of the path tracking, we employ the fuzzy logic controller to conduct the path tracking behavior and obstacle avoidance behavior. Through computer simulation studies, we show the effectiveness of the proposed navigational algorithm for autonomous mobile robots.

• Journal of Satellite, Information and Communications
• /
• v.8 no.3
• /
• pp.41-46
• /
• 2013

In this paper, we present the compatibility study results including the frequency sharing criteria between new allocation to maritime mobile satellite service and Earth exploration satellite service in the 7/8 GHz. The transmitting Earths station of MMSS in the 8025 - 8400 MHz band would make harmful interference to the receiving Earth station of EESS operating in the same frequency band. In order to ensure the compatibility with EESS, the separation distance is provided as a frequency sharing criteria. The republic of Korea has a plan to launch the geostationary satellite around 2017 and EESS Earth station will be operated in 8025 - 8400 MHz band. Therefore, we calculate the interference levels and separation distance using the system parameters of two Earth station systems. As results of the study, the separation distances for LOS path and Non-LOS path due to the geographical characteristics are shown around 471 km and 200 km, respectively.

• The Journal of the Korea Contents Association
• /
• v.12 no.1
• /
• pp.500-507
• /
• 2012

The purpose of this study was to investigate the effects of medicine ball throwing for weight shift training, that make improvements on golf physical fitness and performance. This training was related to physical fitness and golf performance in beginner golfer, undergraduates 20 males(10 exercise groups, 10 control groups) during 10 weeks. Variables were strength, flexibility, headspeed and distance. Training course were devided 2 sessions. In 1 to 5 weeks, using 3kg medicine ball, in 5 to 10 weeks, using 5kg medicine ball. Throwing method imitated golf swing, address, backswing, follow-through by throwing medicine ball. The Results were as follows; Medicine ball throwing for weight shift training showed significant difference in strength, flexibility, headspeed and distance in Exercise Group statistically. In conclusion, Medicine ball throwing for weight shift training improved strength, flexibility, headspeed and distance. So, it could be considered very effective training method as warming-up and main exercise.

• The Journal of Engineering Geology
• /
• v.33 no.1
• /
• pp.201-211
• /
• 2023

This study investigated the damage range of the debris flow to predict the amount of collapsed soil in a landslide event. The height of the collapsed slope and the distance traveled by the collapsed soil were used to predict the total trajectory distance using a random walk model. Debris flow trajectory probabilities were calculated through 10,000 Monte Carlo simulations and were used to calculate the damage range as measured from the landslide scar to its toe. Compiled information on debris flows that occurred in the Cheonwangbong area of Mt. Jirisan was used to test the accuracy of the proposed random walk model in estimating the damage range of debris flow. Results of the comparison reveal that the proposed model shows reasonable accuracy in estimating the damage range of debris flow and that using 10 m × 10 m cells allows the damage range to be reproduced with satisfactory precision.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.8 no.12
• /
• pp.1883-1890
• /
• 2013

Location detection technology (LDT) is one of the core techniques for location based service (LBS) in wireless communication for improving resource management and quality of services. The location of a mobile station (MS) is estimated using the time of arrival (TOA) technique based on three circles with centers corresponding to coordinates of three base stations (BSs) and radius corresponding to distances between MS and BSs. For accurately estimating the location of MS, three circles should meet at a point for the trilateration method, but they generally do not meet a point because the radius is increased depending on the number of time delay for estimating the distance between MS and BS and the carrier frequency. The increased three circles intersect at six points and the three intersection points among them should be generally placed close to coordinate of the location for the specific MS. In this paper, we propose the shortest distance algorithm for TOA trilateration method, to select three interior intersection points from entire six points. The proposed approach selects three intersection points with the shortest distances between coordinates of MS and intersection points and determines the averaged coordinate of the selected three points, as the location of the specific MS. We demonstrate the performance of the proposed algorithm using a typical computer simulation example.

• Journal of the Korean Society of Radiology
• /
• v.6 no.5
• /
• pp.427-433
• /
• 2012

This study aimed at identifying changes in the acromiohumeral distance (AHD) and arm when the caudal gliding gradeII and III of Kaltenborn-Evjenth Concept$^{(R)}$ are applied to the right glenohumeral joint. The humeral head moved down about 5mm from the initial position when the gliding gradeII was applied, and about 8mm from the initial position when the gliding gradeIII was applied. Although men showed a higher acromiohumeral distance per grade than women in comparisons by gender for the acromiohumeral distance, there was no significant difference in statistics. The Abduction angle improved about $10^{\circ}$ from the initial angle when the gliding gradeII was applied, and about $12^{\circ}$ from the initial angle when the gliding gradeIII was applied. Although women showed the abduction angle greater than men for every grade in comparisons by gender for the abduction angle, there was no significant difference in statistics. Based on the aforesaid findings, the extent of kinematic changes in the humeral head could be identified when the gliding grades were applied. Accordingly, it is considered that more scientific evidence based treatments could be expected if influences on the surrounding structures by these changes could be learned through more studies in the future.

• Journal of the Korean GEO-environmental Society
• /
• v.22 no.2
• /
• pp.25-33
• /
• 2021

This study was conducted to understand the deposition characteristics of debris flow and to analyze the reduction effect of debris flow damage by installing a berm. Flume experiments were performed in consideration of various channel slope and volumetric sediment concontration. In order to analyze the reduction effect of debris flow damage by installing a berm, the cases of not installing a berm and the cases of installing a berm were compared. In this study, the runout distance, total travel distance, and mobility ratio were analyzed among the deposition characteristics of debris flow. First, the deposition characteristics of debris flow according to the change of the channel slope were analyzed, and the deposition characteristics of debris flow due to the change of volumetric sediment concentration were analyzed. In addition, the change rate of debris flow deposition characteristics when a berm was installed was calculated based on the case when a berm was not installed. As a result of the experiments, it was confirmed that the channel slope and volumetric sediment concentration had a significant effect on the deposition characteristics of debris flow. In addition, when a berm is installed on the slope, the runout distance and mobility ratio of debris flow are greatly decreased, and the total travel distance is increased. This means that installing a berm delays the movement of debris flow and reduces the potential mobility of debris flow. The results of this study will provide useful information for understanding the deposition characteristics of debris flow. Furthermore, it is expected to help in the design of a berm.