• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.471-478
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• 2020

In this paper, we develop the ground risk model of unmanned aerial vehicle (UAV) operation to quantify the ground risk when the UAV falls to the ground during the intended operation in case of UAV failure. The ground risk is computed by using the UAV failure probability, the probability of impact a person when UAV falls to the ground, the probability of fatality when UAV strikes the person. We mathematically derive each probability to evaluate the ground risk of UAV operation. Also, the population density map, building to land ratio map, car traffic database is used to estimate the number of people exposed to collision with UAV. Finally, we assumed the operations of a UAV with two paths in Daejeon city and evaluate the ground risk of each UAV operations.

• Journal of Environmental Impact Assessment
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• v.4 no.1
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• pp.9-15
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• 1995

For the purpose of saving the waste disposal cost a self-governing community on the whole reclamates the wetland and uses it as a landfill site. During the operation period of site, the environmental impact by the leachate is usually neglected. Therefore, to predict the environmental impact and dispersion of leachate, the wetland adjacent to the South Han River in Chungju is selected as a site of case study. The main content of this article is to apply the simulation model CONMIG to leachate transfer in the ground water and to derive the impact by the leachate. A kind of non-reacting conservative material, chloride ion is used as a tracer to quantify impacts by the leachate.

• Journal of Aerospace System Engineering
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• v.16 no.3
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• pp.52-62
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• 2022

In the SORA methodology developed for the operational risk assessment of a specific category of operation of a UAS, the ground and the air risk levels are determined, and a SAIL indicating the level of assurance and integrity for the corresponding risk is assigned, and accordingly, the operational safety level for the proposed operation. Objectives should be demonstrated at an appropriate level of robustness. Because of the nature of the specific category of operation, people on the ground are the first risk subjects to be considered. The resulting ground risk class plays an important role in the allocation of SAIL. In this paper, the impact on SAIL and OSO according to the final risk level and the reduction of the level through the determination of the ground risk level and the application of mitigation measures among risk assessments for specific categories of UAV operation was investigated.

• Geomechanics and Engineering
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• v.21 no.2
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• pp.111-122
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• 2020

In most cases in urban areas, construction of divergence tunnel should take into account proximity to existing tunnel in operation. This inevitably leads to deformation of adjacent structures and surrounding ground. Preceding researches mainly dealt with reinforcing of the diverging section for the stability including the pillar. This has limitations in investigating the interactive effects between existing structures and surrounding ground due to the excavation of the divergence tunnel. In this study, the complex interactive behavior of pile, the operating tunnel, and the surrounding ground according to horizontal offsets between the two adjacent tunnels was quantitatively analyzed based on conditions diverged from operating tunnel in urban areas. The effects on ground structures confirmed by analyzing the ground surface settlements, pile settlements, and the axial forces of the pile. The axial forces of lining in operating tunnel investigated to estimate their impact on existing tunnel. In addition, in order to identify the deformation of the surrounding ground, the close range photogrammetry applied to the laboratory model test for confirming the underground displacements. Two-dimensional finite element numerical analysis was also performed and compared with the results. It identified that the impact of excavating a divergence tunnel decreased as the horizontal offset increased. In particular, when the horizontal offset was larger than 1.0D (D is the diameter of operating tunnel), the impact on existing structures further reduced and the deformation of surrounding ground was concentrated at the top of the divergence tunnel.

• Journal of the Korea Institute of Military Science and Technology
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• v.26 no.5
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• pp.431-438
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• 2023

The information about battlefield environment changes and operational impacts on Korean Peninsula due to climate change is essential for national defense. In this study, the future impact of four ground operations was analyzed by using the national climate change standard scenario based on the IPCC 6^th report. As a result, it was analyzed that the number of operational-limited days for ambush and airlift operations would decrease, making the operational environment favorable. However, the operational environment unfavorable as the number of operational-limited days for crossing and reconnaissance operations increase, but the number is not large so much.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.36.2-36.2
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• 2008

This paper presents the impact of Japanese radio source on the S-Band communication between KOMPSAT-2 satellite and TT&C ground system. Major specifications such as transmitting EIRP (Effective Isotropic Radiated Power) and location of Japanese terrestrial station were informed from Radio Research Laboratory in Korea Communication Commission. To estimate path loss in S-Band, the distance between Japanese station and TT&C ground system was obtained by using COTS (Commercial Off-The-Shelf) software. After that the signal strength of Japanese radio source placed at the TT&C ground system was calculated from link parameters such as transmitting EIRP, path loss, and receiving antenna gain. Consequently, this paper shows that the degradation caused by Japanese radio source is acceptable to TT&C ground system for satellite operation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.593-598
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• 2009

In this study we present results for the design of ground test system for 4 degree of freedom(DOF) control test is one of the smart UAV ground test. This system is equipped with real smart UAV and Z direction DOF and 3 direction rotation DOF, Ensuring safe operation of the Smart UAV is a top priority. To this end, it is required to do structure analysis and test verification to confirm the design margin and safety. Based on the analysis, the ground test system has been redesigned to meet the structural conditions.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.6
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• pp.58-62
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• 2015

When an emergency generator is running, it supplies the power for critical loads. Generator protection requires the consideration of many abnormal conditions that may occur with generators include overvoltages and ground faults. Modern day power systems create harmonics within the electrical network that can have an impact upon the associated protective system. This paper focuses on the analysing of the cause and development of a solution for the malfunction of induction disc type overcurrent ground relay by generation of harmonics during emergency generator operation.

• Journal of Forest and Environmental Science
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• v.39 no.4
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• pp.203-212
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• 2023

Directional felling is a felling method practised by the Forestry Department in Peninsular Malaysia as prescribed in Field Work Manual (1997) for Selective Management Systems (SMS) in forest harvesting. Determining the direction of tree felling in Peninsular Malaysia is conducted during the pre-felling inventory 1 to 2 years before the felling operation. This study aimed to predict and analyze the direction of tree felling using the vector-based path distance back link method in Geographic Information Systems (GIS) and compare it with the felling direction observed on the ground. The study area is at Balah Forest Reserve, Kelantan, Peninsular Malaysia. A Path Distance Back Link (spatial analyst) function in ArcGIS Pro 3.0 was used in predicting tree felling direction. Meanwhile, a binary classification was used to compare the felling direction estimated using GIS and the tree felling direction observed on the ground. Results revealed that 61.3% of 31 trees predicted using the vector-based projection method were similar to the felling direction observed on the ground. It is important to note that dynamic changes of natural constraints might occur in the middle of tree felling operation, such as weather problems, wind speed, and unpredicted tree falling direction.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.25 no.3
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• pp.61-67
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• 2017

The Nose Landing Gear(NLG) of Rotary Wing Aircraft is an essential equipment in Landing System for pilot to perform a flight mission. It supports the fuselage at ground and absorbs the impact from the ground when landing, thereby, these functions sustain operational capability for pilot and crew. However, the A aircraft caused stick-slip behavior when it was stationed on the ground. Therefore, this paper summarizes pilot comment in operation which are classified by cause of occurrence and the troubleshooting process about each comment. It also describes design improvements which was derived from troubleshooting and suggests verification results of flight test.