• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.88-88
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• 2022

하천법 개정 및 수자원의 조사·계획 및 관리에 관한 법률 제정으로 하상변동조사를 정기적으로 실시하는 것이 의무화 되었고, 지자체가 계획적으로 수자원을 관리할 수 있도록 제도가 마련되고 있다. 하상의 지형측량은 직접 측량할 수 없기 때문에 수심 측량을 통해 간접적으로 이루어지고 있으며, 그 방법은 레벨측량이나 음향측심기를 활용한 접촉식으로 이루어지고 있다. 접촉식 수심측량법은 자료수집이 제한적이기 때문에 공간해상도가 낮고 연속적인 측량이 불가능하다는 한계가 있어 최근에는 LiDAR나 초분광영상을 이용한 원격탐사를 이용한 수심측정 기술이 개발되고있다. 개발된 초분광영상을 이용한 수심측정 기술은 접촉식 조사보다 넓은 지역을 조사할 수 있고, 잦은 빈도로 자료취득이 용이한 드론에 경량 초분광센서를 탑재하여 초분광영상을 취득하고, 최적 밴드비 탐색 알고리즘을 적용해 수심맵 산정이 가능하다. 기존의 초분광 원격탐사 기법은 드론의 경로비행으로 획득한 초분광영상을 면단위의 영상으로 정합한 후 특정 물리량에 대한 분석이 수행되었으며, 수심측정의 경우 모래하천을 대상으로 한 연구가 주를 이루었으며, 하상재료에 대한 평가는 이루어지지 않았었다. 본 연구에서는 기존의 초분광영상을 활용한 수심산정 기법을 식생이 있는 하천에 적용하고, 동일지역에서 식생을 제거한 후의 2가지 케이스에 대해서 시공간(Spatio-temporal)초분광영상과 단면초분광영상에 모두 적용해 보았다. 연구결과, 식생이 없는 경우의 수심산정이 더 높은 정확도를 보였으며, 식생이 있는 경우에는 식생의 높이를 바닥으로 인식한 수심이 산정되었다. 또한, 기존의 단면초분광영상을 이용한 수심산정뿐만 아니라 시공간 초분광영상에서도 수심산정의 높은 정확도를 보여 시공간 초분광영상을 활용한 하상변동(수심변동) 추적의 가능성을 확인하였다.

• Korean Journal of Remote Sensing
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• v.39 no.6_1
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• pp.1331-1339
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• 2023

In support of the National ATM Reformation and Enhancement Plan (NARAE), a trajectory-based aviation weather service is under development through the NARAE-Weather project. Specifically, weather data presented in a standardized digital format facilitates the seamless integration of digital weather data with air traffic information. Thus, this paper introduces an approach that entails structuring numerical model data to integrate aviation weather information and flight trajectory data. The extraction results using structurally transformed data showed superior performance compared to the results extracted from the original data in terms of performance, and this research is poised to enhance the safety and efficiency of airline operations.

• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.888-896
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• 2023

When an aircraft is landing, it is expected that the aircraft will follow a specified approach procedure and then land at the airport. However, depending on the airport situation, neighbouring aircraft or the instructions of the air traffic controller, there can be a deviation from the specified approach. Detecting aircraft approach patterns is necessary for traffic flow and flight safety, and this paper suggests clustering techniques to identify aircraft patterns in the approach segment. The Gaussian Mixture Model (GMM), one of the machine learning techniques, is used to cluster the trajectories of aircraft, and ADS-B data from aircraft landing at the Gimhae airport in 2019 are used. The aircraft trajectories are clustered on the plane, and a total of 86 approach trajectory patterns are extracted using the centroid value of each cluster. Considering the correlation between the approach procedure pattern and overshoots, the distribution of overshoots is calculated.

• Journal of Korea Water Resources Association
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• v.54 no.11
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• pp.903-913
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• 2021

In the flood season, the measurement of the river discharge has many restrictions due to reasons such as budget, manpower, safety, convenience in measurement and so on. In particular, when heavy rain events occur due to typhoons, etc., it is difficult to measure the amount of flood due to the above problems. In order to improve this problem, in this study, a method was developed that can measure the river discharge in a flood season simply and safely in a short time with minimal manpower by combining the functions of a drone and a surface velocity doppler radar. To overcome the mechanical limitations of drones caused by weather issues such as wind and rainfall derived from the measurement of the river discharge using the conventional drone, we developed a drone with P56 grade dustproof and waterproof performance, stable flight capability at a wind speed of up to 36 km/h, and a payload weight of up to 10 kg. Further, to eliminate vibration which is the most important constraint factor in the measurement with a surface velocity doppler radar, a damper plate was developed as a device that combines a drone and a surface velocity Doppler radar. The velocity meter DSVM (Dron and Surface Veloctity Meter using doppler radar) that combines the flight equipment with the velocity meter was produced. The error of ±3.5% occurred as a result of measuring the river discharge using DSVM at the point of Geumsan-gun (Hwangpunggyo) located at Bonghwang stream (the first tributary stream of the Geum River). In addition, when calculating the mean velocity from the measured surface velocity, the measurement was performed using ADCP simultaneously to improve accuracy, and the mean velocity conversion factor (0.92) was calculated by comparing the mean velocity. In this study, the discharge measured by combining a drone and a surface velocity meter was compared with the discharge measured using ADCP and floats, so that the application and utility of DSVM was confirmed.

• The Korean Journal of Air & Space Law and Policy
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• v.32 no.1
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• pp.287-325
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• 2017

Considering the development of aerospace, military science and technology since the 20th century, the sky is very important for the nation's existence and prosperity. The proverb "Whosoever commands the space commands the world itself!" emphasizes the need for the command of the air. This essay is the first study on the status of airspace after reunification. First, the territorial airspace is over the territory and territorial sea, and its horizontal extent is determined by the territorial boundary lines. Acceptance of the present order is most reasonable, rather than attempting to reconfigure through historical truths about border issues, and it could be supported by neighboring countries in the reunification period. For peace in Northeast Asia, the reunified Korea needs to respect the existing border agreement between North Korea and China or Russia. However, the North Korean straight baselines established in the East Sea and the Yellow Sea should be discarded because they are not available under United Nations Convention on the Law of the Sea. It is desirable for the reunified Korea to redefine the straight baselines that comply with international law and determine the territorial waters up to and including the 12-nautical mile outside it. Second, the Flight Information Region (hereinafter "FIR") is a region defined by the International Civil Aviation Organization (hereinafter "ICAO") in order to provide information necessary for the safe and efficient flight of aircraft and the search and rescue of aircraft. At present, Korea is divided into Incheon FIR which is under the jurisdiction of South Korea and Pyongyang FIR which is under the jurisdiction of North Korea. If North Korea can not temporarily exercise control of Pyongyang FIR due to a sudden change of circumstances, it is desirable for South Korea to exercise control of Pyongyang FIR, and if it is unavoidable, ICAO should temporarily exercise it. In reunified Korea, it is desirable to abolish Pyongyang FIR and integrate it into Incheon FIR with the approval of ICAO, considering systematic management and control of FIR, establishment of route, and efficiency of management. Third, the Air Defense Identification Zone (hereinafter "ADIZ") is a zone that requires easy identification, positioning, and control of aircraft for national security purposes, and is set up unilaterally by the country concerned. The US unilaterally established the Korea Air Defense Identification Area (KADIZ) by the Declaration of Commitment on March 22, 1951. The Ministry of Defense proclaimed a new KADIZ which extended to the area including IEODO on December 13, 2013. At present, North Korea's military warning zone is set only at maritime boundaries such as the East Sea and the Yellow Sea. But in view of its lack of function as ADIZ in relations with China and Russia, the reunified Korea has no obligation to succeed it. Since the depth of the Korean peninsula is short, it is necessary to set ADIZ boundary on the outskirts of the territorial airspace to achieve the original purpose of ADIZ. Therefore, KADIZ of the reunified Korea should be newly established by the boundary line that coincides with the Incheon FIR of the reunified Korea. However, if there is no buffer zone overlapping with or adjacent to the ADIZs of neighboring countries, military tensions may rise. Therefore, through bilateral negotiations for peace in Northeast Asia, a buffer zone is established between adjacent ADIZs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.235-242
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• 2017

A driving controller for active destruction protections can be applied to machinery, aerospace and military fields. In particular, this controller can be used to track and attack enemy flying objects through the active control. It is important to ensure reliability of the driving controller since its operation should be kept with precision to the target point. The temperature of the environment where the driving controller is used is about -32 C ~ 50 C (241~323 ). Heat generated in the driving controller should be maintained below a certain threshold (85 C (358 )) to ensure reliability; therefore, the study and analysis of the heat flow characteristics in the driving controller are required. In this research, commercial software Solid-Works Flow Simulation was used for the numerical simulation assuming a low Reynolds number turbulence model and an incompressible viscous flow. The goal of this paper is to design the driving controller safely by analyzing the characteristics of the heat flow inside of the controller composed of chips or boards. Our analysis shows temperature distributions for boards and chips below a certain threshold.

• Korean Journal of Social Welfare
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• v.38
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• pp.153-179
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• 1999

Despite the enforcement of minimum legal drinking age of 18 years of age since 1997, alcohol experimentation among Korean youth is believed to be greater than ever before. The use of alcohol jeopardizes physical, mental, and social development during a person's formative years, thereby endangering successful transitions from adolescent to adulthood. Even infrequent use of alcohol may result in intoxication and acute consequences, especially among youth, who may have low tolerance due to their smaller body size and may lack experience with the effects of alcohol. Using self-report questionnaire data collected from 1,697 highschool students nation-wide, the drinking behavior among Korean high school students and the relation between adolescents' alcohol expectancy and adolescent alcohol use patterns were examined. Results indicated that gender and the type of school(academic or vocational) were significant effects on the drinking behavior(drinking frequency, experience of drunkenness, the amount of alcohol consumed, experience of binge drinking and that of problems due to drinking). Male students than female students, and students of vocational schools rather than those of academic high schools reported more alcohol experimentation. Also, positive alcohol expectancy proved to have a significant relation with alcohol use among high-school students. That is, students who reported to think alcohol would have a positive effect on socializing, aggressiveness, relaxation of tensions, and enforcing sexual ability tended to drink more, to experience more binge drinking and more drinking problems. Variables of gender and the type of school also were found to have significant effects on alcohol expectancy. Males and students of vocational school held ideas of positive outcomes on drinking than others. Implications for further study on developing prevention programs are presented.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.9
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• pp.599-608
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• 2022

Urban air mobility (UAM) equipped with rotor system is subject to ground effect at vertiport during takeoff and landing. The aerodynamic performance of the aircraft in ground effect should be analyzed for the safe operation. In this study, The ground effects on the aerodynamic performance and wake structure of the quadcopter electric vertical takeoff and landing (eVTOL) configuration equipped with coaxial counter-rotating propellers were investigated by using the lattice Boltzmann method (LBM). The influence of the ground effect was observed differently in the upper and lower propellers of the coaxial counter-rotating propeller system. There was no significant change in the aerodynamic performance of the upper propeller even if the propeller height above the ground was changed, whereas the averaged thrust and torque of the lower propeller increased significantly as propeller height decreased. In addition, the amplitude of the thrust fluctuation tended to increase as the propeller height decreased. The propeller wake was not sufficiently propagated downstream and was diffused along the ground due to the outwash flow developed by the ground effect. The impingement of the rotor wakes on the ground and a fountain vortex structure were observed.

• Tunnel and Underground Space
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• v.34 no.1
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• pp.1-14
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• 2024

An image-reconstruction technology, involving the deployment of an unmanned mobility equipped with high-speed LiDAR (Light Detection And Ranging) has been proposed to reconstruct the shape of abandoned mine. Unmanned mobility operation is remarkably useful in abandoned mines fraught with operational difficulties including, but not limited to, obstacles, sludge, underwater and narrow tunnel with the diameter of 1.5 m or more. For cases of real abandoned mines, quadruped robots, quadcopter drones and underwater drones are respectively deployed on land, air, and water-filled sites. In addition to the advantage of scanning the abandoned mines with 2D solid-state lidar sensors, rotation of radiation at an inclination angle offers an increased efficiency for simultaneous reconstruction of mineshaft shapes and detecting obstacles. Sensor and robot posture were used for computing rotation matrices that helped compute geographical coordinates of the solid-state lidar data. Next, the quadruped robot scanned the actual site to reconstruct tunnel shape. Lastly, the optimal elements necessary to increase utility in actual fields were found and proposed.

• The Korean Journal of Air & Space Law and Policy
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• v.24 no.2
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• pp.211-234
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• 2009

North Korea conducted the launcher test, which, as North Korea claimed, belonged to the sovereign rights for the purpose of peaceful utilization and exploration of the outer space. The launching was allegedly done for the sole purpose of putting the satellite into earth orbit, while international community stressed the fact that the orbiting of satellite was not confirmed and that the technology used was not distinct from the purpose of building intercontinental ballistic missile. UN Security Council adopted the resolutions which took the effect that the launching was deemed as the missile launching, not the mere launcher test. North Korea declared the moratorium of suspending its test activity. Controversial issues have been raised regarding whether the launcher itself has the legal status of enjoying the freedom of space flight based upon the 1967 Outer Space Treaty. The resolutions, however, has put forward a binding instrument forbidding the launching. UN Security Council resolutions, however, should be read not as defining the missile test illegal, in that the language of resolutions, such as 'demand', should be considered as not formulating a sort of obligatory act or inact. On the other hand, the resolutions should be read as having binding force with respect to any activity relating to the weapons of mass destruction. The resolution 1718 is written in more specific language such as 'decides that the DPRK shall suspend all activities related to its ballistic missile programme and in this context re-establish its pre-existing commitments to a moratorium on missile launching'. Therefore, the lauching activity of the North Korea is banned by the UN Security Council resolution. It should be noted that the resolution does not include any specific provisions defining the space of activity of the North Korea as illegal. But, the legal effect of the moratorium is not denied as to its launching itself, which is corresponding to the missile test clearisibanned in accordance with the resolutions.