• 한국군사과학기술학회지
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• 제12권5호
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• pp.683-688
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• 2009

A research was conducted about the Reynolds number effect on the projectile with an altitude change. The atmosphere conditions change in accordance with an altitude change. It effects the Reynolds number. To confirm how the phenomena affect the trajectory of the projectile, a computer program is designed with an altitude and a range considered. The MISSILE DATCOM which is based on the semi-empirical method was utilized to get aerodynamic coefficients. The result shows that the Reynolds number considerably changes as the altitude change. It causes to change the drag coefficient of the projectile. As the Reynolds number decreases, the skin friction drag increases significantly. It causes to decrease the maximum altitude and the range.

• 대한지구과학교육학회지
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• 제6권1호
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• pp.28-39
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• 2013

The purpose of this study is to investigate the conceptions about altitude of the Sun of elementary students according to differences by the spatial ability. In this study through the qualitative analysis, 4 students who were similar understanding levels of concepts to altitude of the Sun and differences by the spatial ability were selected out of 75 in 6th grade elementary located in Sunchang, Jellabuk-do Province. 4 students for the qualitative analysis were selected by the test instrument of spatial ability and altitude of the Sun. The results of study was students with higher spatial ability were higher understanding levels of concepts to altitude of the Sun. However, both of student with higher and lower spatial ability showed a false concept to the expanded concepts into outer space like a cause of seasonal change, change of altitude of the Sun by latitude unlike the intution. Students with lower spatial ability didn't form the scientific concepts, not only a cause of seasonal change and change of altitude of the Sun but also difference of energy density by altitude of the Sun. A student of two with lower spatial ability has been impediment strongly to form the scientific concept by the false concepts to the distance. The findings were as follows; Learning to altitude of the Sun regardless of the difference of spatial ability should be learned to interact to the intution, celestial movement and model experiment. To students with lower spatial ability should be developed teaching methods to understand the relation between the Sun and celestial movement.

• 전기전자학회논문지
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• 제22권3호
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• pp.747-753
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• 2018

Currently, many companies have succeeded in logistics delivery experiments utilizing drone and report it. When a drone is used commercially, long-term flight is an important performance that a drone should have. However, unlike vehicles operated on the ground, drone is a vehicle that continues to consume energy when maintaining the current altitude or moving to the destination. Therefore, the drones can fly for a long time as the capacity of the battery is large, but the batteries with large capacity are restricted by heavy weight and it acts as a limiting factor in a commercial use. To address this issue, we attempt to compare how far we can fly than forward flight based on the flight pattern with the same energy consumption condition. In this paper, the comparison of energy consumption was performed in three flight pattern, forward flight without altitude change and forward flight with altitude change, by computer simulation and it shows the increasing of flight distances when the quadrotor fly with altitude change from high altitude to low altitude.

• Journal of information and communication convergence engineering
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• 제16권2호
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• pp.78-83
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• 2018

Rapidity and accuracy are important considerations when a drone is employed in a wide surveillance area to detect a target. They are more important when the scope of application is a search and rescue operation or the monitoring of natural disasters, which may require prompt warnings and response. During the actual operation of a drone, rapidity and accuracy are associated with the change in the altitude of the drone. The aim of this study is to analyze the characteristics of drones at varying altitudes and prove that altitude is a relevant factor in the performance of drones. Herein, the characteristics of the drone at varying altitudes were analyzed through several search simulations. The results suggest that a high-altitude drone is relatively advantageous compared to a low-altitude drone in a probability-based target search, and that the search altitude is also a very important and fundamental factor in target search by drones.

• 제어로봇시스템학회논문지
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• 제14권12호
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• pp.1232-1237
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• 2008

This paper introduces an application of wavelet analysis to the sensor fusion of GPS/INS/baroaltimeter. Using wavelet analysis the baro-inertial altitude is decomposed into the low frequency content and the high frequency content. The high frequency components, 'details', represent the perturbed altitude change from the long time trend. GPS altitude is also broken down by a wavelet decomposition. The low frequency components, 'approximations', of the decomposed signal address the long-term trend of altitude. It is proposed that the final altitude be determined as the sum of both the details of the baro-inertial altitude and the approximations of GPS altitude. Then the final altitude exclude long-term baro-inertial errors and short-term GPS errors. Finally, it is shown from the test results that the proposed method produces continuous and sensitive altitude successfully.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제6권10호
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• pp.473-478
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• 2017

드론은 비행 목적을 달성하기 위해 고도 유지를 필요로 하는 경우가 많다. 일반적으로 드론의 고도 유지 기능은 현재 측정되는 고도 정보에 따라 드론을 상승시키거나 하강시키는 작업을 반복하는 것을 의미한다. 고도 유지 중에 모터 속도 차이로 인한 추력의 불균형이나 바람 등의 외적 요인으로 인해 드론의 고도가 계속 변한다. 그럼에도 불구하고 고도를 유지하기 위해서는 기본적으로 계속해서 변하는 드론의 고도를 정확하게 측정해야 한다. 드론의 고도 측정 방법은 일반적으로 가속도센서를 사용한다. 이 방법은 적분 오차 누적으로 인한 측정값이 발산하는 문제와 드론의 기체 진동조차 고도 변화로 인지하는 문제가 존재한다. 그래서 상용 드론이나 기존 연구에서는 가속도센서를 제외한 별도의 센서를 추가하여 고도 측정에 사용한다. 그러나 추가하는 센서 대부분은 측정거리에 제한이 있으며 여러 센서들을 같이 사용하는 경우 센서 값들의 연산 처리가 많아져 고도 측정 속도가 지연될 우려가 있다. 따라서 드론의 고도 유지, 고도 측정 성능에 영향을 주지 않으면서 정확한 고도를 측정할 수 있는 방안이 필요하다. 본 논문에서는 가속도센서를 이용하는 일반적인 고도 측정 방법을 개선한 측정 알고리즘을 제안하고 본 알고리즘을 적용한 결과로 고도 유지와 고도 측정의 정확성이 향상됨을 보인다.

• 한국지형학회지
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• 제19권2호
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• pp.99-111
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• 2012

본 연구는 대전분지에 있어서 청동기시대에서 원삼국시대로의 이행과정에서 나타나는 주거지의 지리적(또는 지형적) 입지환경 변화와 그 원인을 밝히는 것이다. 이를 위하여 (1) '유적그룹(또는 주거지밀집유적)의 주거지 총수 비교'그리고 (2) '두 시대의 주거지를 모두 포함하고 있는 특정유적에서 주거지 총 수 비교'로 구분하여 시대변천에 따른 주거지의 표고, 경사도, 용수하천거리 및 용수하상비고 측면에서 입지환경을 상호 비교하였다. 그 결과는 다음과 같다. 1. 개별 인자의 변화를 보면, 표고는 상승했으며, 경사도는 증가했다. 용수하천거리는 소급하천의 경우 감소 내지 증가했으며, 중급하천의 경우 거의 차이가 없거나 증가했다. 그리고 용수하상비고는 소급하천의 경우 증가했으며, 중급하천의 경우 증가 내지 감소했다. 2. 개별 인자를 상호 비교하면, 경사도, 표고 및 용수하상비고의 증감이 대체로 유사한 경향을 띠며, 특히 경사도의 증가가 표고와 용수하상비고의 증가에 영향을 미치는 것으로 나타났다. 그리고 용수하천거리의 증감은 경사도, 표고 및 용수하상비고의 증감과 다른 경향을 나타내는 것으로 나타났다. 3. 이상으로부터 대전분지 내에 분포하는 저구릉의 미지형적 특성(예 : 경사도 특성)과 저구릉을 둘러싸고 있는 풍부한 수계환경이 서로 맞물려 당시의 주거지 입지선정에 영향을 미쳤다는 것을 알 수 있었다. 특히 당시 거주민들에게 주거지 입지 선정시 '경사도와 용수하천거리'가 '표고와 용수하상비고'에 비해 상대적으로 중요한 주거지 선정 인자였던 것으로 밝혀졌다.

• 반도체디스플레이기술학회지
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• 제9권1호
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• pp.67-71
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• 2010

Head up display’s cooling system is auto-diagnosed resulting from the external environment. The quantity of heat depending on this Head up display’s cooling system layout determines the speed of FAN for system cooling. In other words, a system’s heat quantity is planned through the air density depending on altitude, the amount of wind in air depending on FAN control condition, and the algorithm that is proportional to delta temperature. To detect the altitude, we use the criteria of delta T, which is determined by the subtracted value of LED junction temperature, and atmospheric temperature that is recorded on the Head up display system. Depending on the classification of delta T value, the altitude section is determined. While we can use GPS as the tool to detect the altitude, we should predict the change of the air density as the altitude alters, and should not just measure the altitude. And the value of delta T is used as the criterion of detecting the altitude for increasing the cooling efficiency of the car’s inner Head up display system with reflecting the speed of the FAN dependent upon the air density. In our theory, altitude is depending on the value of delta T and stabilizing or maintaining the system’s temperature by changing FAN’s rpm depending on determined value of altitude.

• Journal of Astronomy and Space Sciences
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• 제31권1호
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• pp.33-39
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• 2014

This paper describes an experimental approach to evaluate the effective doses of space radiations at high-altitude by combining the measured data from the Liulin-6K spectrometer loaded onto the air-borne RC-800 cockpit and the calculated data from CARI-6M code developed by FAA. In this paper, 15 exposed dose experiments for the flight missions at a high-altitude above 10 km and 3 experiments at a normal altitude below 4 km were executed over the Korean Peninsula in 2012. The results from the high-altitude flight measurements show a dramatic change in the exposed doses as the altitude increases. The effective dose levels (an average of $15.27{\mu}Sv$) of aircrew at the high-altitude are an order of magnitude larger than those (an average of $0.30{\mu}Sv$) of the normal altitude flight. The comparison was made between the measure dose levels and the calculated dose levels and those were similar each other. It indicates that the annual dose levels of the aircrew boarding RC-800 could be above 1 mSv. These results suggest that a proper procedure to manage the exposed dose of aircrew is required for ROK Air Force.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.216-221
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• 2002

A spherical Earth surface is used fur realistic analysis of the geometrical performance characteristics about the variation of satellite altitude and 2-dimensional line-of-sight(LOS) tilt angle in a satellite imager using Time Delay and Integration(TDI) technique with fixed integration time. In the spherical Earth surface model TDI synchronization using LOS tilt is investigated as a solution to compensate geometric performance degradation due to altitude decrease. This result can be used fur a TDI CCD imager with variable integration time in a certain as well.