• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.476-477
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• 2022

This study deals with rotation, which is one of the expression methods of motion used in the 3D development environment. Euler angle is a rotation method introduced by Leonhard Euler to display objects in three-dimensional space. Although three angles can handle all rotations in a three dimensional coordinate space, there are serious errors in this approach. If you rotate an object with Euler angles, you will face the problem of gimbal locks that cannot rotate under certain circumstances. In contrast to this, the method to rotate an object without a gimbal lock is the quaternion rotation with quaternion. Rather than a detailed mathematical proof of quaternion, it introduces what concept is used in the current 3D development environment, and applies it to camera rotation control to implement a rotating camera without a gimbal lock.

• Journal of Advanced Navigation Technology
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• v.25 no.6
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• pp.441-449
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• 2021

With advances in autonomous vehicles, there is a growing demand for more accurate position estimation. Especially, this is a case for a moving robot for the indoor operation which necessitates the higher accuracy in position estimation when the robot is required to execute the task at a predestined location. Thus, a method for improving the position estimation which is applicable to both the fixed and the moving object is proposed. The proposed method exploits the initial position estimation from Bluetooth beacon signals as observation signals. Then, it estimates the gravitational acceleration applied to each axis in an inertial frame coordinate through computing roll and pitch angles and combining them with magnetometer measurements to compute yaw angle. Finally, it refines the control inputs for an object with motion dynamics by computing acceleration on each axis, which is used for improving the performance of Kalman filter. The experimental assessment of the proposed algorithm shows that it improves the position estimation accuracy in comparison to a conventional Kalman filter in terms of average error distance at both the fixed and moving states.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.4
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• pp.133-137
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• 2016

The video and audio information occupies a large portion of the IoT information. Various sensors can be used in a more accurate situation awareness and the absence of the main information has been required. Increasing in resource management in accordance with the use of various sensors. As a method to reduce the resources required in the communication of the various sensors and find the possibility to process the sensor information that can take the place of the other sensor. In this paper, using the LIS302 DL MEMS motion sensor to measure the data in the ping-pong ball, shuttlecock, tennis ball falling into table tennis. Data measured in the three object was confirmed that in proportion to the amount of impact. This experiment using the accelerometer can be confirmed that changes in the amount of impact. The results using a single multi-function sensor showed a possible implementation. In addition, the recognized in consideration of the situation in the early development stage of the multi-function sensor.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.5
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• pp.488-497
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• 2009

The freak wave, also known as New-Year-Wave in the north Atlantic, is relatively large and spontaneous ocean surface wave that can sink even large ships and destroy maritime structures. To understand oceanic conditions that develop freak waves, we simulated and generated two versions of scale-downed waves (1:64 and 1:42) in a numerical wave tank and compared the results with the experiment in wave flume. Both of the breaking and non-breaking waves were generated in the simulation. The numerical simulation was implemented based on the finite volume method and a genetic optimization algorithm. Random values were assigned as the initial values for the parameter in the control function, which produced signals representing the motion of wave-maker. The same signal obtained from the optimization process was used for both of the simulation and the experiment. By varying the object function and restrictions of the simulation, a best profile of design wave was selected based on the characteristics, height and period of simulated waves. Results showed that the simulation and experiment with the scale of 1:42 agreed better with freak waves in the natural condition. The presented simulation method will contribute to saving the time and cost for conducting subsequent response analyses of motion under freak waves in the course of the model test for ship and maritime structure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.806-811
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• 2005

The robot to search and rescue is used in narrow space where human cannot approach. In case of this robot, it can overcome obstacles such as wrecks or stairs etc. Also, this robot can do various locomotion for each object. In this reason, an articulated robot has advantages comparing with one module robot. However, the existing articulated robot has limits to overcome vertical passages. For expanding contacted territory of robot, a novel mechanism is demanded. In this paper, the novel mechanism of articulated mobile robot is designed for moving level ground and vertical passages. This paper proposes to change wheel alignment. The robot needs two important motions for passing vertical passages like pipe. One is a motion to press wheels at wall for not falling into gravity direction. The other is a motion that wheels contact a vertical direction of wall's tangential direction for reducing loss of force. The mechanism of the robot focused that two motions can be acted to use just one motor. Length of each link of robot is optimized that wheels contact a vertical direction of wall's tangential direction through kinematic modeling of each link. The force of pressing wall of robot is calculated through dynamic modeling. This robot composes four modules. This mechanism is confirmed by dynamic simulation using ADAMS program. The articulated mobile robot is elaborated based on the results of kinematic modeling and dynamic simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.4
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• pp.812-820
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• 2012

In this paper, multiple pedestrians tracking system using Histogram of Oriented Gradient and occlusion detection is proposed. The proposed system is applicable to Intelligent Surveillance System. First, we detect pedestrian in a image sequence using pedestrian's feature. To get pedestrian's feature, we make block-histogram using gradient's direction histogram based on HOG(Histogram of Oriented Gradient), after that a pedestrian region is classified by using Linear-SVM(Support Vector Machine) training. Next, moving objects are tracked by using position information of the classified pedestrians. And we create motion trajectory descriptor which is used for content based event retrieval. The experimental results show that the proposed method is more fast, accurate and effective than conventional methods.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.5
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• pp.709-714
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• 2018

Visual Reality technology is becoming more and more interesting as it attracts people's interest. VR technology is used in various markets such as games, animation, and education. However, there were many people experiencing motion sickness such as dizziness and headache due to the delay time between hardware such as a device for sending a video after experiencing a VR image and an HMD for reproducing an image. The system proposed in this paper focuses on the environment rather than the movement of the attraction and detects the dividing line existing on the path by the proximity sensor and accurately calculates the position on the path according to the user 's motion. Since the position of the user is synchronized with the VR image, the position error of the user is improved to 0.2%.

• Proceedings of KOSOMES biannual meeting
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• 2006.11a
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• pp.303-308
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• 2006

In this paper, the authors calculated manoeuvring motions of a large container vessel approaching to the newly built container piers to get alongside to her berth in Busan harbour. The motion calculations were done by using fixed coordinate system and the object of the calculations is to check the manoeuvring motions are safe or not for berthing the large vessel to her berth. The result of calculations manifested that a large container vessel can get alongside to the piers without any difficulty under normal weather conditions by using 2 Z. Peller tug boats of 4500 H.P. each and also these demonstrated it is difficult to conduct and get her alongside to the piers under rough weather conditions of wind force 16.9m/sec or more. Under rough weather conditions of 6 by beaufort scale the average wind velocity is about 13.5m and if we add 25% increase of the normal velocity to it, the wind will becomes a gust of 16.9m/sec. So it is advisable to avoid conducting a large container vessel to the pier under the rough weather conditions of 6 or more by beaufort scale. Also, I is better to use 3 Z. peller tug boats of 4500 HP. each under the above mentioned rough weather in a case of unavoidable circumstances.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1998.10a
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• pp.413-414
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• 1998

This paper presents a real-time Spatial Decision Support System(SDSS) for security camera image monitoring. Other SDSSs are not real-time systems, i.e., they show the images that are already transformed into data format such as virtual reality. In our system, the image is broadcasted in real-time since the purpose of the security camera needs to do it in real-time. With these real-time images, other systems do not add up anything more; the screen just shows the images from the camera. However in our system, we created a motion detection system so that the supervisor(Judge) of a sec.urity monitoring system does not have to pay attention to it constantly. In other words, we created a judge advising system for the supervisor of the security monitoring system. Most of small objects do not need the supervisor's attention since they could be birds, cats, dogs, etc. if they show up in the screen image. In this new system the system only report the unusual change to the supervisor by calculating the motion and size of objects in the screen. Thus the supervisor can be liberated from the 24-hour concentration duty; instead he/she can be only alerted when the real security threat such as a big moving object like an human intruder appears. Thus this system can be called a real-time Spatial DSS. The utility of this system is proved mathematically by using the concept of entropy. In other words, big objects like human intruders increase the entropy of the screen images significantly therefore the supervisor must be alerted. Thus by proving its utility of the system theoretically, we can claim that our new real-time SDSS is superior to others which do not use our technique.hnique.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.5
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• pp.45-51
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• 2011

In this paper, we propose an unsupervised learning method for modeling motion trajectory patterns effectively. In our approach, observations of an object on a trajectory are treated as words in a document for latent dirichlet allocation algorithm which is used for clustering words on the topic in natural language process. This allows clustering topics (e.g. go straight, turn left, turn right) effectively in complex scenes, such as crossroads. After this procedure, we learn patterns of word sequences in each cluster using Baum-Welch algorithm used to find the unknown parameters in a hidden markov model. Evaluation of abnormality can be done using forward algorithm by comparing learned sequence and input sequence. Results of experiments show that modeling of semantic region is robust against noise in various scene.