• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.4
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• pp.311-318
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• 2020

This study investigates the performance and blade airloads for a rigid coaxial rotor of high-speed compound unmanned rotorcrafts. The present compound unmanned rotorcraft uses not only a rigid coaxial rotor, but also wings and propellers for high-speed flights. For the rigid coaxial rotor in this work, CAMRAD II, a rotorcraft comprehensive analysis code, is used to study the performance at a flight speed of up to 250 knots and blade section lift forces at 230 knots. As the flight speed increases, the rotor power decreases; however, the power of propellers increases to overcome the drag force of a rotorcraft in high-speed flight. The effective lift-to-drag ratio of a rotor has the maximum value of about 11.6 which is much higher than the value of the conventional helicopter. The blade section lift forces of the upper and lower rotors at 230 knots show the similar variation trends for one rotor revolution, and the impulses because of the aerodynamic interaction between both rotors are observed.

• Journal of Biosystems Engineering
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• v.34 no.2
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• pp.89-94
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• 2009

Aerial application using an agricultural unmanned helicopter was suggested for an alternative against current pesticide application methods. Centrifugal clutches play important roles in the performance and safety of the helicopter operation. A previous study analyzed and verified the power transfer theory of the guide type centrifugal clutch. Based on the clutch theory, optimal designs of the clutch became possible and feasible using a simulation method. Design criteria of the clutch were the power transfer capacity of 24.66 kW(33.5 PS) at the rated engine speed and the engaging range speed of 3,000${\sim}$3,500 rpm. Various designs were accomplished using the simulation. An optimal clutch was simulated by determining the values of spring constant and mass of friction sector, which were 94,700 N/m and 123.7 g, respectively. The design performed the power capacity of 24.86 kW(33.8 PS) and engagement speed of 3,069 rpm, meeting the design criteria. Using the designed clutch, an efficient transfer of the power would be possible for the unmanned agricultural helicopter.

• Journal of Navigation and Port Research
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• v.35 no.2
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• pp.121-130
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• 2011

The localization of vehicle is an important part of an unmanned vehicle control problem. Pseudolite ultrasonic system(PUS) is the method to find an absolute position with a high accuracy by using ultrasonic sensor. And Gyro is the inertial sensor to measure yaw angle of vehicle. PUS can be able to estimate the position of mobile robot precisely, in which errors are not accumulated. And Gyro is a more faster measure method than PUS. In this paper, we suggest a more accuracy method of calculating PUS which is numerical analysis approach named Newtonian method. And also propose the fusion method to increase the accuracy of estimated angle on moving vehicle by using PUS and Gyro integrated system by Kalman filtering. To control the 4WS unmanned vehicle, the trajectory following algorithm is suggested. And the new concept arbitration of goal controller is suggested. This method considers the desirability function of vehicle state. Finally, the performances of Newtonian method and designed controller were verified from the experimental results with the 4WS vehicle scaled 1/10.

• Journal of Ocean Engineering and Technology
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• v.30 no.5
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• pp.426-430
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• 2016

Recently, many unmanned surface vehicles (USVs) have been developed and researched for various fields such as the military, environment, and robotics. In order to perform purpose specific tasks, common autonomous navigation technologies are needed. Obstacle avoidance is important for safe autonomous navigation. This paper describes a vector field histogram+ (VFH+) based obstacle avoidance method that uses the monocular vision of an unmanned surface vehicle. After creating a polar histogram using VFH+, an open space without the histogram is selected in the moving direction. Instead of distance sensor data, monocular vision data are used for make the polar histogram, which includes obstacle information. An object on the water is recognized as an obstacle because this method is for USV. The results of a simulation with sea images showed that we can verify a change in the moving direction according to the position of objects.

• Journal of Korea Multimedia Society
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• v.24 no.10
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• pp.1346-1357
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• 2021

The drone technology, which is receiving a lot of attention due to the 4th industrial revolution, requires an Unmanned Aerial Vehicles'(UAVs) flight path search algorithm for automatic operation and driver assistance. Various studies related to flight path prediction and recommendation algorithms are being actively conducted, and many studies using the A-Star algorithm are typically performed. In this paper, we propose an Optimal 3D Flight Path Recommendation System for unmanned aerial vehicles. The proposed system was implemented and simulated in Unity 3D, and by indicating the meaning of the route using three different colors, such as planned route, the recommended route, and the current route were compared each other. And obstacle response experiments were conducted to cope with bad weather. It is expected that the proposed system will provide an improved user experience compared to the existing system through accurate and real-time adaptive path prediction in a 3D mixed reality environment.

• Journal of the Korea Convergence Society
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• v.12 no.7
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• pp.1-6
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• 2021

Currently, virus infection such as Corona 19 has become commonplace, and interest in unmanned systems is increasing in the field for non-face-to-face ICT services. In this paper, the function and performance of remotely successfully controlling a store through video and audio using an IP PBX with a broadcasting function was verified through a test. And the fully unmanned system is not gaining credibility due to various technical problems, however the central control system is a very efficient and reliable system because the controller can directly control the customer while monitoring the access and the inside of the store through the video and audio. In the future, we plan to study a completely unmanned remote control system using A.I technology.

• Journal of Korea Multimedia Society
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• v.21 no.11
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• pp.1305-1316
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• 2018

Graphical user interface(GUI) has a very important role to interact with software users. However, designing and coding of GUI are tedious and pain taking processes. In many studies, the researchers are trying to convert GUI elements or widgets to code or describe formally their structures by help of domain knowledge of stochastic methods. In this paper, we propose the GUI elements detection approach based on object detection strategy using deep neural networks(DNN). Object detection with DNN is the approach that integrates localization and classification techniques. From the experimental result, if we selected the appropriate object detection model, the results can be used for automatic code generation from the sketch or capture images. The successful GUI elements detection can describe the objects as hierarchical structures of elements and transform their information to appropriate code by object description translator that will be studied at future.

• Journal of Aerospace System Engineering
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• v.13 no.3
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• pp.40-47
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• 2019

This paper proposes the environment construction and test method of system integration laboratory (SIL) and system integration test (SIT) for verification of interface between onboard equipment and ground control equipment of unmanned aerial systems (UAS). This research also describes the interface environment between subsystems built in SIL and verification methods for the systems' operation logic through simulated flights. Similarly, the paper handles the ground integration test process of UAS in the real testing environments.

• Journal of Aerospace System Engineering
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• v.13 no.3
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• pp.48-55
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• 2019

This paper presents a study on Fault History Management Equipment (FHME) of Unmanned Aerial Systems (UAS). UAS comprise of various types of electronic equipment for high reliability design for flight safety. Consequently, it is mandatory for each on-board equipment to have its own Built-In-Test (BIT) function, because rapid fault-detections for UAS are necessary. FHME is developed for the purposes of display, storage and management of such BIT results on ground. This paper describes the outline, development requirements, design and verification process of FHME.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.4
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• pp.266-273
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• 2019

The efficiency and effectiveness of mission performance can be greatly changed according to the operating conditions such as the number of manned aircraft, flight altitude, and so on, in performing search and reconnaissance missions using a large number of small reconnaissance unmanned aerial vehicles. However, it is not easy to determine which operating conditions are most reasonable. Therefore, in this study, we developed an unmanned airplane flight simulation that can detect and identify the target while avoiding collision according to autonomous flight, suggesting a way to derive operating conditions when operating a large number of unmanned aerial vehicles.