• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.272-275
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• 2007

The combustion efficiency of the solid fuel ramjet is affected by the inlet air temperature. And this inlet air temperature is dependent on the flight Mach number and the environment air temperature. If the flight altitude is changeable, the inlet air temperature and also the air density vary. The performance efficiency is investigated with this variables related to the combustion efficiency.

• Journal of Advanced Navigation Technology
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• v.4 no.2
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• pp.182-190
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• 2000

In this paper, interference effects between NGSO and HAPS in the feeder link have been simulated and analyzed by means of calculating excess time percent and duration below the ell protection ratio. As the results, in the case of HAPS interference into NGSO, it can be obtained that the lowest C/I values are 20.42dB in 50km and 12.73dB in 20km of HAPS altitudes, respectively. And in the case of NGSO interference into HAPS, it can be obtained that the lowest ell values are 13.94dB and 10.42dB respectively. HAPS system has more interference reception from other systems or effects more interference into other systems as its altitude is lower. Also, the lowest ell values are appeared at difference time with its altitude.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.34-38
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• 2000

In this paper, interference effects between NGSO and HAPS in the feeder link have been simulated and analyzed by means of calculating excess time percent and duration below the C/I protection ratio. As the results, in the case of HAPS interference into NGSO, it can be obtained that the lowest C/I values are 27.42dB in 50km and 12.73dB in 20Km of HAPS altitudes, respectively. And in the case of NGSO interference into HAPS, it can be obtained that the lowest C/I values are 13.94dB and 10.42dB respectively. HAPS system has more interference reception from other systems or effects more interference into other systems as its altitude is lower. Also, the lowest C/I values are appeared at difference time with its altitude.

• Journal of Astronomy and Space Sciences
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• v.7 no.1
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• pp.37-45
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• 1990

It was investigated that the effect of zonal harmonics to transfer orbit. Since parking orbit is located at low altitude, the zonal harmonics affects transfer orbit relatively high sense. So under the zonal harmonics, eccentricity and semi-major-axis which were related orbit altitude at the first hand, were investigated. As a result the zonal harmonics increases the altitude of apogee of transfer orbit. So if the zonal harmonics is considered in orbit transfer the fuel can be saved a little.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.216-216
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• 2016

제주도의 한라산은 고도의 영향으로 해안지역과 산간지역의 기온 차이가 크게 나타나는 지역이다. 이러한 특성으로 겨울철 제주도의 해안지역에는 강우가 내리고 산간지역에는 강설이 발생한다. 특히, 강설이 발생하는 고도는 일별 기상상황에 따라 다르게 나타난다. 그러나 제주지방기상청에서는 제주도의 8개 지점에서만 적설량을 관측하고 있어 강설이 발생하는 고도를 정확히 파악하기 어렵다. 이에 본 연구에서는 제주도의 한라산을 대상으로 성산기상레이더와 고산기상레이더의 반사도 자료를 이용하여 2014년 11월부터 2015년 4월까지의 강설 고도 변화를 분석하였다. 먼저, 레이더 반사도의 고도를 해수면으로부터 250 m 간격으로 2,000 m 까지 구분하였다. 또한, 구간별로 레이더 자료와 AWS 자료를 이용하여 Z-S 관계식을 유도하였다. 마지막으로, 유도된 고도별 Z-S 관계식의 변화를 파악하여 겨울철 한라산의 강설 고도 변화를 분석하였다.

• Korean Journal of Heritage: History & Science
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• v.48 no.4
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• pp.94-109
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• 2015

This study examines Korea's revitalization policy on the ancient capital cities, which has been set out for preserving and improving living quality of the local communities. Since it was established, the policy has faced with constant challenges such as the lack of funding for preservation and revitalization of local communities. This study aims at providing a set of recommendation on the problems on the policy. In order for the study, it takes objective and empirical analysis on the problems of the policy by executing survey on the satisfaction level of the stakeholders and policy-makers on the present policy. The survey has displayed that the government needs to 1. subsidize more budget, 2. set out a policy to reduce the inconvenience of local communities 3. establish a supportive program to help the present promotion policy. In addition, the survey analysis has proved that the elements of revitalization policy affect to the increase of satisfaction. It concludes with a set of recommendation, 1. to secure sufficient budget to implement the policy; 2. to reduce a restriction of individual rights; 3. to promote the supporting program of local community; 4. to establish governance system with officers, experts, residents, and research institutes.

• Korean Journal of Remote Sensing
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• v.29 no.1
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• pp.81-94
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• 2013

The Radar altimeter transmits radio signals to the surface, receives the backscattered signals and measures the distance between the airplane and the nadir surface. The measurements of radar altimeter are affected by various factors on the surface below the aircraft. This study performed flight campaigns in June 2012 and acquired raw data from radar altimeter, LiDAR and other sensors. Based on the LiDAR DSM (Digital Surface Model) as a reference data, the characteristics of radar altimeter were analyzed in the respect of range and surface area affecting on the receiving power of the radar altimeter. Consequently, the radar altimeter was strongly affected by the surface area within beam width and reflectivity related to RCS (Radar Cross Section) rather than range.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.2
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• pp.83-92
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• 2022

This paper analyzes the performance of the IRA(Interferometric Radar Altimeter) by terrain type for estimating reliability of TRN(Terrain Referenced Navigation). The accuracy of the altitude is one of the key parameters of TRN's accuracy. When the antenna of the IRA has wide beamwidth, its altitude accuracy is directly affected by the configuration of the earth's surface. Hence, the accuracy and reliability of TRN can also be affected and may cause ambiguity in positioning. We present analysis data for estimating the reliability of TRN by modeling several topographies and analyzing the performance of the IRA. The results of the analysis are verified by comparison with test data.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.10
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• pp.473-478
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• 2017

Drones require altitude holding in order to achieve flight objectives. The altitude holding of the drone is to repeat the operation of raising or lowering the drone according to the altitude information being measured in real-time. When the drones are maintained altitude, the drone's altitude will continue to change due to external factors such as imbalance in thrust due to difference in motor speed or wind. Therefore, in order to maintain the altitude of drone, we have to exactly measure the continuously changing altitude of the drone. Generally, the acceleration sensor is used for measuring the height of the drones. In this method, there is a problem that the measured value due to the integration error accumulates, and the drone's vibration is recognized by the altitude change. To solve the difficulty of the altitude measurement, commercial drones and existing studies are used for altitude measurement together with acceleration sensors by adding other sensors. However, most of the additional sensors have a limitation on the measurement distance and when the sensors are used together, the calculation processing of the sensor values increases and the altitude measurement speed is delayed. Therefore, it is necessary to accurately measure the altitude of the drone without considering additional sensors or devices. In this paper, we propose a measurement algorithm that improves general altitude measurement method using acceleration sensor and show that accuracy of altitude holding and altitude measurement is improved as a result of applying this algorithm.

• Journal of Animal Science and Technology
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• v.54 no.1
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• pp.51-58
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• 2012

The purposes of the study were to examine the changes in carcass traits and surface meat color, and cortisol concentration by different altitudes and shipping distances for steer and cow. The experimental animals were shipped from Kangwondo, Kyunggido, Choongchungdo, and Kyungsangdo to Wonju LPC. The animals were examined for yield traits, quality traits, carcass grade, lightness, redness, yellowness, croma value, and cortisol concentration by different altitudes and shipping distances. The results showed that the carcass traits of steer like back fat thickness were not different by shipping distances of 100 km, 150 km, and 200 km. However, the fat thickness was higher in steers shipped from 250 km than 100 km, 150 km, and 200 km distance. Ribeye area was reduced significantly in 200 km and 250 km than 50 km. Yield index and yield grade were significantly low in 250 km than 50-200 km. However, meat color, fat color, texture, mature, and quality grade had no differences between shipping distances. Marbling score was not different in 50-200 km. However, the marbling score in 250 km was significantly lower than that of 50 km. In case of surface meat color by shipping distance, redness, yellowness, chroma value, and hue-angle were not different in shipping distance of 250 km. The lightness had similar result in 50-200 km. However, in case of 250 km the lightness was significantly low. The REA of cow carcass by shipping distance had no differences by shipping distance. The BET had similar results in 50-150 km. However, it had significantly thick in 200 km. The yield index and yield grade had no differences in 50-150 km. However, yield index and grade were significantly low in 200 km. The carcass trait of cow had no differences in all items by shipping distance. Although the carcass traits and the BET for steer by altitude had no differences between 100, 200, 300 and 500 m, but those were significantly thick in 400 m. And the yield index and the yield grade at altitude 400 m were lower than that of other altitudes. The quality traits and the quality grade had no differences between 100, 200, 300, 400, and 500 m altitudes. The yield traits, quality traits, yield grade, and quality grade had no significant differences by altitudes. In case of yield index of cow for 300 m was low than the cases of 100 m and 200 m. The surface meat color for steer and cow had no differences by altitudes. However, the lightness of cow had positive result in 100 m than 200 m and 300 m. In case of steer and cow the cortisol concentration by shipping distance was high as the shipping distances were longer. However, the cortisol concentrations of steer and cow by altitudes were decreased as the altitudes were increased. From the above results carcass traits and carcass grade were decreased and the cortisol concentration was increased as the altitudes were decreased for steer and cow.