• Journal of Satellite, Information and Communications
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• v.6 no.2
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• pp.107-111
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• 2011

In World War II, the solar eruption (solar flare) was revealed to make a significant effect to radar systems. The radio disturbance in February 28, 1942 was due to increased cosmic ray during solar maximum. Since such phenomena had been disclosed, many studies were accomplished on solar flare and solar particle event. Now various researches about the effects of solar flare on the spacecrafts, the airplanes flying across the pole, the radar systems, and wireless communication systems are studied. In this paper we analyzed the relationship between the harmful effect on the wireless communication by the solar eruption and the period of solar activity from the sunspot number data and the solar radio burst data for last 40 years.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.227-231
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• 2004

Technological advance in information technology has sparked the necessity of small form factor (SFF) optical disk for mobile devices. Small form factor optical disk is highly anticipated to be a next generation storage device because it can be used for a cost-effective way compared with solid state memory. For the application to the 5 mm height small-form-factor optical disk drive, we have presented an optical flying head and swing arm actuator. In this study, we propose a small 1-axis actuator for compensating ficus error and SA due to the variation of cover-layer thickness in the cover-layered small optical disk. The main design issues of the 1-axis actuator are the realization of compact structure and the new support structure of the actuator: Finally, the compensating principle and performance of the 1-axis actuator will be explained.

• Journal of Convergence for Information Technology
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• v.9 no.9
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• pp.141-146
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• 2019

The aircraft noise analysis area in this study is a training airfield where various kinds of aircraft are operated. It is difficult to identify the noise analysis as a real measurement in a training airfield. In order to overcome these practical limitations and to establish appropriate noise countermeasures, a noise map is prepared using the Integrated Noise Model Version 7.0 of the aircraft noise prediction program used by the FAA. The noise of C90GT aircraft was measured while flying the takeoff route, landing route, and long route. We want to identify areas where noise damage is more than 70 WECPNL. No area exceeding the legal standard of 70 WECPNL was found in all routes.

• Journal of Astronomy and Space Sciences
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• v.35 no.4
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• pp.263-277
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• 2018

This paper presents a vision-based relative pose estimation algorithm and its validation through both numerical and hardware experiments. The algorithm and the hardware system were simultaneously designed considering actual experimental conditions. Two estimation techniques were utilized to estimate relative pose; one was a nonlinear least square method for initial estimation, and the other was an extended Kalman Filter for subsequent on-line estimation. A measurement model of the vision sensor and equations of motion including nonlinear perturbations were utilized in the estimation process. Numerical simulations were performed and analyzed for both the autonomous docking and formation flying scenarios. A configuration of LED-based beacons was designed to avoid measurement singularity, and its structural information was implemented in the estimation algorithm. The proposed algorithm was verified again in the experimental environment by using the Autonomous Spacecraft Test Environment for Rendezvous In proXimity (ASTERIX) facility. Additionally, a laser distance meter was added to the estimation algorithm to improve the relative position estimation accuracy. Throughout this study, the performance required for autonomous docking could be presented by confirming the change in estimation accuracy with respect to the level of measurement error. In addition, hardware experiments confirmed the effectiveness of the suggested algorithm and its applicability to actual tasks in the real world.

• Journal of Hydrogen and New Energy
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• v.34 no.6
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• pp.758-766
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• 2023

Multi-copter of unmanned aerial vehicle (UAV) was initially developed as strategic technology in the only military field, but it is developing into an industrial field with a wide range of applications in the civil sector based on the development and convergence of aviation technology and information and communication technology. Currently, the degree of utilization of multi-copter is increasing in various industries for the purpose of performing classic tactical missions, logistics transportation, farm management, internet supply, video filming, weather management, life-saving, etc, and active technology development responding to market demand. Existing commercial multi-copter mainly use an electric energy propulsion system consisting of an electric battery and a brushless direct current (BLDC) motor. It is the limitations for usage in the flying time (up to 20 minutes) and payload (less than 20 kg). this study aims to overcome these limitations and expand the commercialization of engine-powered multi-copter of UAV in various industries in the futures.

• Journal of Food Hygiene and Safety
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• v.35 no.1
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• pp.45-50
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• 2020

In this study, seafood products (n=26) sold on sushi buffet restaurants in the city of Wonju were monitored by analyzing sequences of DNA barcode markers (cytochrome c oxidase subunit I and 16S ribosomal RNA genes). NCBI BLAST database was screened with the barcode sequences analyzed as a query for species identification. The BLAST search revealed that fifteen samples (58%) analyzed were consistent with their labeling information; however, the ingredients used in seven samples (27%) were not compliant with their label information. In the case of these mislabeled products, ingredients for sutchi catfish sushi and cherry bass sashimi were identified as Pangasianodon hypophthalmus and Lampris guttatus, respectively. For Japanese flying-fish roe sushi and Pacific herring roe sushi, roe of Mallotus villosus was used as an ingredient. Amphioctopus fangsiao and A. membranaceus were used in octopus sushi and soybean-marinated squid products, respectively. This monitoring result can contribute to the protection of consumer rights and the reduction of fraudulent practices in the food industry.

• Journal of the Korea Society of Computer and Information
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• v.17 no.4
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• pp.99-107
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• 2012

We propose control mechanism of UAV(Unmanned Aerial Vehicle) group for making the communication network to the base station after the target is found. We assume UAVs can communicate to each other by wireless LAN without existing communication infrastructure. UAVs started to fly in linear formation, after finding target, UAVs move to the base station to send the information about the target. At least one UAV stays the position that the target is found. This paper explains the mechanism supporting reliable connectivity during UAV group's flying. We verify the proposed scheme and evaluate the performance through NS-2 simulation. The proposed scheme can be applied to the disaster area and war zone, which the existing communication infrastructure cannot be worked.

• International Journal of Computer Science & Network Security
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• v.23 no.9
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• pp.150-156
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• 2023

For a doctor, diagnosing a patient's heart disease is not easy. It takes the ability and experience with high flying hours to be able to accurately diagnose the type of patient's heart disease based on the existing factors in the patient. Several studies have been carried out to develop tools to identify types of heart disease in patients. However, most only focus on the results of patient answers and lab results, the rest use only echocardiography data or electrocardiogram results. This research was conducted to test how accurate the results of the classification of heart disease by using two medical data, namely echocardiography and electrocardiogram. Three treatments were applied to the two medical data and analyzed using the decision tree approach. The first treatment was to build a classification model for types of heart disease based on echocardiography and electrocardiogram data, the second treatment only used echocardiography data and the third treatment only used electrocardiogram data. The results showed that the classification of types of heart disease in the first treatment had a higher level of accuracy than the second and third treatments. The accuracy level for the first, second and third treatment were 78.95%, 73.69% and 50%, respectively. This shows that in order to diagnose the type of patient's heart disease, it is advisable to look at the records of both the patient's medical data (echocardiography and electrocardiogram) to get an accurate level of diagnosis results that can be accounted for.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.4
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• pp.318-324
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• 2017

We introduced a stereo camera on the aircraft to detect flight objects and to estimate the 3D position of them. The Saliency map algorithm based on PCT was proposed to detect a small object between clouds, and then we processed a stereo matching algorithm to find out the disparity between the left and right camera. In order to extract accurate disparity, cost aggregation region was used as a variable region to adapt to detection object. In this paper, we use the detection result as the cost aggregation region. In order to extract more precise disparity, sub-pixel interpolation is used to extract float type-disparity at sub-pixel level. We also proposed a method to estimate the spatial position of an object by using camera parameters. It is expected that it can be applied to image - based object detection and collision avoidance system of autonomous aircraft in the future.

• Journal of Advanced Navigation Technology
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• v.2 no.2
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• pp.132-142
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• 1998

In optical scanning holography, 3-D holographic information of an object is generated by 2-D active optical scanning. The optical scanning beam can be a time-dependent Gaussian apodized Fresnel zone plate. In this technique, the holographic information manifests itself as an electrical signal which can be sent to an electron-beam-addressed spatial light modulator for coherent image reconstruction. This technique can be applied to 3-D optical remote sensing especially for identifying flying objects. In this paper, we first briefly review optical scanning holography and analyze the resolution achievable with the system. We then present mathematical expression of real and virtual image which are responsible for holographic image reconstruction by using Gaussian beam profile.