• Journal of Satellite, Information and Communications
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• v.9 no.3
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• pp.1-4
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• 2014

A radio communication system has interference caused by other radio transmitters operated in co-channel or adjacent channels. Therefore technical specifications are made by considering and investigating the effects of interference between the new system and present systems when the new system will be started to serve in the near future. FTS is used for preventing an abnormal mission and guaranteeing public protection. Recently the next generation FTS's are researched to reinforce the security and to increase the operating capability of simultaneous use. EFTS known as one of the next generation FTS's is suitable for such purposes. In this paper the effects of interference signals on the performance of EFTS are investigated. Noncoherent DPSK and noncoherent CPFSK are considered for the modulation method of EFTS and a FMCW and a pulse RADAR considered as a interferer. The power of FMCW is 20.3dB lower than the power of EFTS and the power of pulse RADAR is 19.1dB lower than that of EFTS. Simulation results show that FMCW interferer reduce $E_b/N_o$ of about 1dB and $E_b/N_o$ of EFTS deteriorates about 0.5dB due to interference signals generated from pulse RADAR.

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1125-1139
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• 2022

In an unmanned aerial vehicles (UAVs) system, a physical offset can be existed between the global positioning system/inertial measurement unit (GPS/IMU) sensor and the observation sensor such as a hyperspectral sensor, and a lidar sensor. As a result of the physical offset, a misalignment between each image can be occurred along with a flight direction. In particular, in a case of multi-sensor system, an observation sensor has to be replaced regularly to equip another observation sensor, and then, a high cost should be paid to acquire a calibration parameter. In this study, we establish a precise sensor model equation to apply for a multiple sensor in common and propose an independent physical offset estimation method. The proposed method consists of 3 steps. Firstly, we define an appropriate rotation matrix for our system, and an initial sensor model equation for direct-georeferencing. Next, an observation equation for the physical offset estimation is established by extracting a corresponding point between a ground control point and the observed data from a sensor. Finally, the physical offset is estimated based on the observed data, and the precise sensor model equation is established by applying the estimated parameters to the initial sensor model equation. 4 region's datasets(Jeon-ju, Incheon, Alaska, Norway) with a different latitude, longitude were compared to analyze the effects of the calibration parameter. We confirmed that a misalignment between images were adjusted after applying for the physical offset in the sensor model equation. An absolute position accuracy was analyzed in the Incheon dataset, compared to a ground control point. For the hyperspectral image, root mean square error (RMSE) for X, Y direction was calculated for 0.12 m, and for the point cloud, RMSE was calculated for 0.03 m. Furthermore, a relative position accuracy for a specific point between the adjusted point cloud and the hyperspectral images were also analyzed for 0.07 m, so we confirmed that a precise data mapping is available for an observation without a ground control point through the proposed estimation method, and we also confirmed a possibility of multi-sensor fusion. From this study, we expect that a flexible multi-sensor platform system can be operated through the independent parameter estimation method with an economic cost saving.

• Korean Journal of Environment and Ecology
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• v.33 no.6
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• pp.624-635
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• 2019

Bird strike accidents, a collision between aircraft and birds, have been increasing annually due to an increasing number of aircraft operating each year to meet heavier demand for air traffic. As such, many airports have conducted studies to assess and manage bird strike risks effectively by identifying and ranking bird species that can damage aircraft based on the bird strike records. This study was intended to investigate the bird species that were likely to threaten aircraft and compare and discuss the risk of each species estimated by the single-matrix and multi-matrix risk assessment models based on the Integrated Flight Information Service (IFIS) data collected in Gimpo, Gimhae and Jeju Airports in South Korea from 2005 to 2013. We found that there was a difference in the assessment results between the two models. The single-matrix model estimated 2 species and 6 taxa in Gimpo and Gimhae Airports and 2 species and 5 taxa in Jeju Airport to have the risk score above "high," whereas the multi-matrix model estimated 3 species and 5 taxa in Gimpo Airport, 4 species and 5 taxa in Gimhae Airport, and 2 species and 3 taxa in Jeju Airport to have the risk score above "very high." Although both models estimated the similar high-risk species in Gimpo and Gimhae Airports, there was a significant difference in Jeju Airport. Gimpo and Gimhae Airports are near the estuary of a river, which is an excellent habitat for large and heavy waterbirds. On the other hand, Jeju Airport is near the coast and the city center, and small and light bird species are mostly observed. Since collisions with such species have little effect on aircraft fuselage, the impact of common variables between the two models was small, and the additional variables caused a significant difference between the estimation by the two models.

• Korean Journal of Social Welfare
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• v.61 no.4
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• pp.5-33
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• 2009

This study attempted to evaluate the effectiveness of the Supportive Project for the Priority Region of Educational Welfare Investment(SPPREWI) which has been put into action in Korea as a part of national policies for poor school children. In so doing this study aimed to test SPPREWI's legitimacy as well as whether we have to continue this program or not. In order to fulfill this research purpose researchers identified several outcome indicators of SPPREWI, which represent psychosocial and cognitive adjustment. The variables pertaining to psychosocial adjustment domain are: self-concept; depression, anxiety, and suicidal impulse; inclination of assault and indignation; delinquency; school life adjustment; and change in social relations. The variables of cognitive adjustment include recognition of self-control in learning; control strategy of learning behavior; and preparedness for job hunting. In this study the quasi-experimental group contained students from schools which are under the SPPREWI. The control group was composed of students from schools which were free from SPPREWI but under the influence of deteriorating school environment. The quasi-experimental group and the control group were compared in terms of outcome indicators presented earlier. Within the quasi-experimental group both the students below poverty-line and the students above poverty-line were divided into two groups each by the level of service use, and were compared in terms of the outcome variables presented earlier. Study results supported the argument that SPPREWI was effective generally in improving students' school adjustment. Study results also showed that the variable of 'school nurturance' played a significant role in moderating the effect of SPPREWI on a couple of outcome variables specially when schools' overall educational environment was in poor condition. Implication as well as suggestion were presented on the basis of study findings.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.10
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• pp.217-230
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• 2012

This paper propose interacting test programming methods between test equipment and hardware unit to verify function and performance of the hardware unit under test. Proposed test program can minimizes the risk of failures when the unit is mounted on the aircraft by testing and verifying the unit under the worst stress condition. Also, Object oriented design using UML make it easy to apply in other equipments. Test program consists of architecture package and hardware package. Architecture package is in a role for system management, log analysis, message receiving and message analysis. Messages that are used by system management define messages for testing and defined messages is sent and received to test equipment through Ethernet. Hardware package is in a role for hardware management that is needed to be tested and is related to a system. Hardware to be tested is divided into internal test and transmission test. Internal test inspects hardware itself and reports the test results to the test equipment. Transmission test inspects communication device by sending or receiving data. All kinds of test is done in the worst condition of the test unit executing in parallel. Each device is tested at least 482 times and at most 15,003 times about one hour. Test program is utilized in hardware reliability test like as environmental test or EMI test.

• Science of Emotion and Sensibility
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• v.10 no.4
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• pp.539-554
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• 2007

Pilots of large airplanes have to land their airplanes with insufficient visual information because of high approach speed, high vertical velocity and high location or altitude of the cockpits from the runway intending to touch down. This study verifies that, due to the insufficient information, large airplane pilots can't exactly perceive height of their airplanes during the flare. Study 1 explored whether it's possible for the pilots to accurately perceive height with the static visual cues only. We showed them pictures of the runway taken from the pilot's pionts of view and asked them to assess the height of the airplanes. They determined exact height of the airplanes at the height of 85 feet, but they could not, at lower than 55 feet which is the flare preparation altitude. Study 2 explored whether it's possible for the pilots to accurately perceive height when dynamic cues were added to the static visual cues. We showed them videos of the runway taken from the pilot's pionts of view. With more cues they determined exact height of the airplanes at the height of 50 feet, but they could not, at the altitude of lower than 30 feet which is the flare altitude. As experience is believed to be a major factor which affects interpretation of the visual cues, we compared the accuracy of the assessment of the experienced captions and that of the in-experienced first officers. We found there was no significant difference between them.

• Spatial Information Research
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• v.12 no.2
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• pp.181-191
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• 2004

Nowadays, GPS-photogrammetry can be applied to the basemap production, a land register and NGIS. And from now on, as the increase of GPS receiver rate, the study on the interpolation methods considering the exact movement of an aircraft at photoflight and the study on the supplement of GPS defect by INS are required continuously. GPS-Photogrammetry, which are based on the direct measurement of the projection centers and attitude at the moment of camera exposure time through loading the GPS receiver in aircraft. This photogrammetric methods can of for us to acquire the exterior orientation parameters with only minimum ground control points, even the ground control process could be completely skipped. Consequently, we can drastically reduce the time and cost far the mapping process. In this thesis, two test flights were conducted in area to evaluate the performance of accuracy and efficiency through the analysis of results between the two photogrammetric methods, that is, traditional photograrammetry, GPS-Photogrammetry. Test results shows that a large variety of advantages of GPS-Photogrammetry against traditional photogrammetry is to be verified. Especially, the number of ground control points for the exterior orientation could be saved more than 70～80%, and the cost far map production 30～50%, respectively. In addition, it was convinced that the large reduction of control points has not any effect on the block accuracy.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.5
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• pp.103-111
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• 2021

The purpose of this study is to study a method for preventing collisions of multiple drones in controlled airspace. As a result of the study, it was proved that it is appropriate as a method to control drone collisions after setting accurate information on the ROI (Region of Interest) area estimated based on the expected drone path and time in the control system as a method to avoid drone collision. As a result of the empirical analysis, the diameter of the flight path of the operating drone should be selected to reduce the risk of collision, and the change in the departure time and operating speed of the operating drone did not act as an influencing factor in the collision. In addition, it has been demonstrated that providing flight priority is one of the appropriate methods as a countermeasure to avoid collisions. For collision avoidance methods, not only drone sensor-based collision avoidance, but also collision avoidance can be doubled by monitoring and predicting collisions in the control system and performing real-time control. This study is meaningful in that it provided an idea for a method for preventing collisions of multiple drones in controlled airspace and conducted practical tests. This helps to solve the problem of collisions that occur when multiple drones of different types are operating based on the control system. This study will contribute to the development of related industries by preventing accidents caused by drone collisions and providing a safe drone operation environment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.8
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• pp.582-589
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• 2019

The dynamic balancing test of helicopter main rotor blades is a blade rotation test conducted on the ground to make the track of each blade and the load on each pitch rod to a similar level before the flight tests. The purpose of the test is to reduce the vibration occurring on main rotor system as a result of dissimilarity of each blade. The RTB test has been performed for a long period at Whirl Tower Test Facility located in Goheung Flight Centre, accumulating its data. As the amount of the results has become increasingly enormous the needs for the development of database system has been raised to manage the data with effective method. This research aimed to describe the development of Dynamic-Balancing Database System for the RTB test results. For the design of the database system the informations of RTB test results have been categorized into properties, connecting each others according to its logical meaning, and comprised into a database system with relational elements. It has been shown in this paper that the Dynamic Balancing database system enables to effectively accumulate the RTB test data and to be utilized for the data analysis.

• The Korean Journal of Air & Space Law and Policy
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• v.24 no.1
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• pp.119-152
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• 2009

Korea now has a rapidly expanding and developing space programme with exploration aspirations. The government is giving priority to the aerospace industry and, to put it on a better footing, enacted an Aerospace Industry Development Promotion Act in I987, a Space Development Promotion Act in 2005 and a Space Compensation for Damage Act in 2007. I would like to describe briefly the legislative history, main contents and comment for these three space acts including especially launch licensing, registration of space objects, use of satellite information, astronaut rescue, liability for compensation, third party liability insurance and establishment of committee and plans to assist the Korean space effort. Furthermore author proposed to legislate a new draft for the establishment of a Korean Aerospace Development Agency (KADA: tentative title) to create a similar body to Japan Aerospace Exploration Agency (JAXA), British National Space Centre (BNSC) of UK, French Centre National d'Etudes Spatiales (CNES), German Aerospace Center (DLR), Swedish Space Corporation (SSC), China Aerospace Science and Industry Corporation (CASIC), Indian Space Research Organization (ISRO) as well as the Korean Space Agency (KSA: Tentative title) to create a similar body to Canadian Space Agency, European Space Agency, Russian Space Agency, Italian Space Agency, Israel Space Agency, Indian Department of Space, National Aeronautics and Space Administration (NASA) of USA, China National Space Administration in order to develope efficiently space industry. If the Korean government will be establish the Korean Space Agency as an governmental organization in future, it is necessary to revise the contents of the Government Organization Act. It is desirable and necessary for us to establish an Asian Space Agency (ASA), in order to develop our space industry and to promote research cooperation among Asian countries, based on oriental idea and creative powers.