• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.1
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• pp.72-86
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• 1998

This paper introduces a simple yet accurate method to predict burst rate and durence expected in a meteor burst communication path in question by comparing its path specifications to those of an exiting path. In this article, the authors analyze the method to derive the burst rate and duration by comparing span distance, frequency, antenna gain, transmitting power and thre- shold level to those of a existing path selected for the reference. the authors further report the result of experiments made for two difference paths; 750 km path and 1,200 km path to Hamamatu Japan and Hatinohe Japan from Kyongsan korea respectively. The occuring rate and average length of the bursts measured on the experiment paths show fairly good agreement with the analysis.

• Journal of the Korea Society of Computer and Information
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• v.15 no.8
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• pp.99-105
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• 2010

Because in the amusement park, a number of people use various vehicles facilities complicated arraigned, it needs an effective way to search optimal path to reduce errors in touring a park. Particularly, when choosing a facility, searching a waiting time-based path as well as shortest path is important. This paper presents a path recommendation system which minimizes total park tour time based on tour distance and waiting time through GPS and wireless internet. This system can also recommend customized tour path based on the characteristics of user members as well as a simple shortest path.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.5
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• pp.471-478
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• 2011

This UGV (Unmanned Ground Vehicle) is not only widely used in various practical applications but is also currently being researched in many disciplines. In particular, obstacle avoidance is considered one of the most important technologies in the navigation of an unmanned vehicle. In this paper, we introduce a simple algorithm for path planning in order to reach a destination while avoiding a polygonal-shaped static obstacle. To effectively avoid such an obstacle, a path planned near the obstacle is much shorter than a path planned far from the obstacle, on the condition that both paths guarantee that the robot will not collide with the obstacle. So, to generate a path near the obstacle, we have developed an algorithm that combines an edge detection method and a limit-cycle navigation method. The edge detection method, based on Hough Transform and IR sensors, finds an obstacle's edge, and the limit-cycle navigation method generates a path that is smooth enough to reach a detected obstacle's edge. And we proposed novel algorithm to solve local minima using the virtual wall in the local vision. Finally, we verify performances of the proposed algorithm through simulations and experiments.

• Journal of Korea Multimedia Society
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• v.24 no.11
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• pp.1538-1551
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• 2021

The current drone flight plan creation creates a flight path point of two-dimensional coordinates on the map and sets an arbitrary altitude value considering the altitude of the terrain and the possible flight altitude. If the created flight path is a simple terrain such as a mountain or field, or if the user is familiar with the terrain, setting the flight altitude will not be difficult. However, for drone flight in a city where buildings are dense, a safer and more precise flight path generation method is needed. In this study, using high-precision spatial information, we construct a drone safety flight map with a 3D grid map structure and propose a flight path search algorithm based on it. The safety of the flight path is checked through the virtual drone flight simulation extracted by searching for the flight path based on the 3D grid map created by setting weights on the properties of obstacles and terrain such as buildings.

• Current Optics and Photonics
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• v.3 no.3
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• pp.210-214
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• 2019

The allowable path-deviation time of aircraft in a free-space optical communication system has been estimated from various trajectories, using different values of aircraft speeds and turn rates. We assumed the existence of a link between the aircraft and a ground base station. First, the transmitter beam's divergence angle was calculated through two different approaches, one based on a simple optical-link equation, and the other based on an attenuation coefficient. From the calculations, the discrepancy between the two approaches was negligible when the link distance was approximately 110 km, and was under 5% when the link distance ranged from 80 to 140 km. Subsequently, the allowable path-deviation time of the aircraft within the tracking-error tolerance of the system was estimated, using different aircraft speeds, turn rates, and link distances. The results indicated that the allowable path-deviation time was primarily determined by the aircraft's speed and turn rate. For example, the allowable path-deviation time was estimated to be ~3.5 s for an aircraft speed of 166.68 km/h, a turn rate of $90^{\circ}/min$, and a link distance of 100 km. Furthermore, for a constant aircraft speed and turn rate, the path-deviation time was observed to be almost unchanged when the link distance ranged from 80 to 140 km.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.208-214
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• 2000

Reduction of structure-borne noise of the compartment in a car is an important task in automotive engineering. Transfer path analysis using vibroacoustic reciprocity technique or multiple path decomposition method has generally been used for structure-borne noise path analysis. These methods are useful in solving particular problem but do not quantify the effectiveness of vibration isolation of each isolator of a vehicle. To quantify the effectiveness of vibration isolation, the vibrational power flow has been used for a simple isolation system or a laboratory based isolation system. It is often difficult to apply the vibrational power flow technique to the complex isolation system like a car. In this paper, a simple equation is derived for calculation of the vibrational power flow of an isolation system with multiple isolators such as a car. It is successfully applied to not only quantifying the relative contributions of eighteen isolators but also reducing structure-borne noise of a passenger car. According to the results, the main contributor of eighteen isolators is the rear roll mount of an engine. The reduced structure-borne noise level is about 5dBA.

• The Journal of Korean Academy of Prosthodontics
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• v.17 no.1
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• pp.7-21
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• 1979

This investigation was to analyse normal protrusive and lateral condylar pantographic records written on the sagittal plane and to study components of Fisher's angle and their interrelations. The purpose of this study was limited to (1) discussing the significance of sagittal pantographic record in diagnosis of occlusal disease and(2) basing for reasoning validity of measuring Fisher's angle which has been reported so far. As a result followings were concluded. 1. In each protrusive and lateral condylar movement path, five complicate factors such as initial straightness, distributed simple sigmoid type, simple curvature, initial tiny protruding convexity and tiny repeated sigmoid patterns were noted. Generally each condylar movement path was composed of two to three of these factors. 2. The distribution of positional interrelations of protrusive and lateral condylar paths could be divided into five categories; (a) protrusive-upper, (b) completely coinciding, (c) partially initial coinciding, (d) partially inverted crossing, and (e) completely inverting. Among these, protrusive path-upper positioned condyles were prevailed (79.2%). 3. The distribution of interrelations of protrusive and lateral condylar paths could be devided into five categories according to their distances in the course of movement. Among these, opening (95.8%) and paralleling (66.7%) were prevailing. 4. The involved number of characteristic heterogenous patterns of five categories in protrusive and lateral condylar movement recording relations at one simultaneous recordings was limited to three. However, in case of homogeneous patterns were repeated, usually three to four were included. 5. The maximum distance between protrusive and lateral condylar paths was 1.45mm at the location of 4mm advanced position from centric relation point and 3.90mm at the location of protrusive movement terminal. 6. It seemed to be that ,pantographic records should be consulted other clinical symptoms in order to make certain occlusion diagnosis. 7. At the present moment of investigation, expressing Fisher's angle as a degree revealed a lack due to inherent complexity of protrusive and lateral condylar movement paths. 8. The typical pattern of protrusive and lateral condylar paths written on a pantographic sagittal plate might be described as follows; (a) protrusive condylar path should be positioned upwardly, (b) both mainly be simple curvature, (c) interrelations mainly be opening or paralleling. 9. The mean amounts of separation between protrusive and lateral condylar movement path were $0.75{\pm}0.46$ at 4mm advanced location from centric relation and $1.74{\pm}0.64mm$ at the location of protrusive path terminal.

• Journal of Korean Society of Transportation
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• v.23 no.6 s.84
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• pp.19-30
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• 2005

The objective of this research is to keep track of path travel time using methods of collecting traffic data. Users of traffic information are looking for extensive information on path travel time, which is referred to as the time taken for traveling from the origin to the destination. However, all the information available is the average path travel times, which is a simple sum of the average link travel times. The average path travel time services are not up to the expectation of traffic information consumers. To improve provide more accurate path travel time services, this research makes a number of different estimates of various path travel times on one path, assuming it will be under the same condition, and provides a range of estimates with their probabilities to the consumers, who are looking for detailed information. To estimate the distribution of the path travel times as a combination of link travel times. this research analyzes the relation between the link travel time and path travel time. Based on the result of the estimation. this research develops the algorithm that combines the distribution of link travel time and estimates the path travel time based on the link travel times. This algorithm was tested and proven to be highly reliable for estimating the path traffic time.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1012-1016
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• 2004

In this paper, we propose a simple but optimized NC code generating technique for disk cams by means of tool path error control in a five-axis CNC machining center. Using the geometric theorem of the triangle made between manufacturing points and error checkpoint, the tool path error has been studied for disk cams profile generation and an improvement in the profile has been obtained. Then, based on the present manufacturing approach a computer program is developed on $C^{++}$ language to perform and to verify the shape design, the manufacturing simulation, and the optimized generation of the NC code.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.11 no.1
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• pp.49-53
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• 2011

Path following of the mobile robot is one research hot for the mobile robot navigation. For the control system of the wheeled mobile robot(WMR) being in nonhonolomic system and the complex relations among the control parameters, it is difficult to solve the problem based on traditional mathematics model. In this paper, we presents a simple and effective way of implementing an adaptive following controller based on the PID for mobile robot path following. The method uses a non-linear model of mobile robot kinematics and thus allows an accurate prediction of the future trajectories. The proposed controller has a parallel structure that consists of PID controller with a fixed gain. The control law is constructed on the basis of Lyapunov stability theory. Computer simulation for a differentially driven nonholonomic mobile robot is carried out in the velocity and orientation tracking control of the nonholonomic WMR. The simulation results of wheel type mobile robot platform are given to show the effectiveness of the proposed algorithm.