• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.1
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• pp.89-94
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• 2006

DGPS provides less altitude accuracy than horizontal accuracy according to geometric characteristics of GPS satellite arrangement. To assist DGPS altitude measurements, two barometric altitude sensors were used and set up at the mobile and the reference station respectively to get the differential altitude. This differential altitude is coupled with the DGPS altitude measurement by a Kalman filter so that the improved altitude is estimated. The differential altitude is based on the relative altitude measurement but results in providing the absolute altitude. The precision of this differential altitude is verified by experiments in accordance with a baseline length.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.455-458
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• 2006

관성항법장치는 관성항법장치를 구성하는 관성센서인 가속도계 및 자이로의 오차요소에 의해 수평축 항법오차는 슐러주기를 가지고 서서히 증가하는 반면에 수직축 오차는 기하급수적으로 증가하는 특성을 가지고 있다. 그러므로 관성항법장치를 장시간 운용하는 경우에는 비관성 보조센서를 이용하여 관성항법장치의 수직축 항법오차에 대한 보정을 반드시 수행하여야 한다. 관성항법장치의 수직축 항법오차를 보정하기 위한 비관성 보조센서의 일종인 기압고도계는 계측된 대기압과 모델링 된 대기압을 비교하여 항체의 고도를 측정하는 방법을 이용하기 때문에 항체의 자세변화 등에 매우 민감하고 대기압 측정오차에 의해 매우 큰 진폭의 잡음 및 바이어스가 존재한다. 본 논문에서는 시뮬레이션 및 시험을 통하여 기압 고도계의 잡음 및 바이어스 오차 성분에 의한 baro-inertial 고도루프의 성능분석 결과를 제시하고 기압고도계 잡음에 둔감한 INS/기압고도계 칼만필터의 설계 결과를 제시한다.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.632-637
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• 2006

본 논문에서는 가상현실 환경에서 방위각, 고도, 거리 등의 위치 정보를 인지할 수 있는 3 차원 사운드를 생성하기 위한 구조적 머리전달함수(Head-Related Transfer Function, HRTF) 모델을 제안하고 이를 구현한다. 이를 위해 우선 기존에 연구된 방위각과 고도에 관한 head model 과 pinna model 을 근간으로 거리의 변화를 고려하도록 하는 HRTF 모델을 제안한다. 제안된 거리 변화에 따른 HRTF 모델은 거리 차이에 따른 음압의 변화 모델과 근거리에서 사람의 머리에 의해 생기는 shadowing 모델로 구성된다. 본 논문에서는 제안한 모델로 부터 mono 사운드를 방위각, 고도, 거리를 인지할 수 있는 stereo 사운드로 변환하여 생성하는 3 차원 사운드 생성기를 구현하였고, 일반인을 대상으로 거리에 대한 청취 실험을 통하여 제안한 모델의 성능을 측정하였다. 그리고 제안된 모델을 가상현실의 실감모델인 MP3 에 구현하여 그 효과를 입증하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.1
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• pp.43-50
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• 2007

In this study, Hybrid Separate Learning Algorithm(SLA) consisting of Support Vector Machine(SVM) and Artificial Neural Network(ANN) has been used for developing the defect diagnostic algorithm of the aircraft turbo-shaft engine in the off-design range considering altitude variation. Although the number of teaming data and test data highly increases more than 6 times compared with those required for the design condition, the proposed defect diagnostics of gas turbine engine using SLA was verified to give the high defect classification accuracy in the off-design range considering altitude variation.

• Proceedings of the KSRS Conference
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• 2007.03a
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• pp.177-182
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• 2007

한반도 주변해역에서의 해수면 고도는 1993년부터 2005년까지의 기간 동안 연평균 3.89 mm $yr^{-1}$ 상승하였으며， 이는 전세계 해수면 상승률의 1.3배에 해당한다. 본 연구에서는 AVISO (Archiving, Validation and Interpretation of Satellite Oceanographic data)에서 제공하는 복합위성자료 (Topex/Poseidon, Jason-1, ERS, Envisat)인 DT-MSLA (Delayed Time - Maps of Sea Level Anomalies)를 이용하여 동해와 황해, 남해, 한국해협에서의 해수면 고도 변화를 연구하였다. 해수면 고도의 평균적인 변화는 증가하는 경향을 보임과 동시에, 여름에는 $4{\sim}5$년，겨울에는 3년의 주기성을 가지고 진동하였다. 조화분석을 통하여 해수면 고도와 해수면 온도의 연주기 모드와 반년주기 모드의 진폭과 위상을 나타내었다. 해수면 고도의 연주기 진폭은 한반도 주변해역에서 남동쪽이 높게，북서쪽이 낮게 나타나는 반면, 해수면 온도는 이와는 반대의 분포를 보였다. 월별 해수면 고도와 해수면 온도의 상관을 구한 결과，$6{\sim}8$월에 동해와 남해에서 1 / 2달 시간지연 일 때，상관계수가 0.7정도로 높게 나타났다. 이러한 결과를 통해 여름철 동해와 남해가 쿠로시오 해류의 영향을 크게 받고 있음을 짐작할 수 있다.

• Korean Journal of Environment and Ecology
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• v.34 no.2
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• pp.115-120
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• 2020

This study investigated the dominant species and the population variation of the ant species, an indicator species of biodiversity, to obtain basic data on the changes of population according to the future climate change. The survey period was from June to September 2013, and we investigated the distribution of ants by square irradiation method (10m × 10m) using traps. The survey in each altitude identified a total of 14 species of 11 genera in 3 subfamilies and collected 15,466 individuals. We confirmed the distribution of 4,548 individuals of 13 species at low altitude (700m), and the dominant species was Aphaenogaster japonica (49.9%). At the middle altitude (900m), we collected 9,129 individuals of 8 species, and the dominant species was Pheidole fervida (57.7%). At high altitude (1,100m), we identified 1,789 individuals of 10 species, and Myrmica kotokui (43.3%) was the dominant species. It was confirmed that Aphaenogaster japonica, Nylanderia flavipes, and Pheidole fervida were widely distributed throughout the altitudes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.6
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• pp.51-56
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• 2005

This paper introduces an altitude determination algorithm using GPS/INS/Baroaltimeter and evaluates the algorithm by real field tests. The test results show that the proposed method can determine the altitude of an aircraft continuously and sensitively. Therefore, it is appropriate to be used as an altimeter for a flight control system, especially for the automatic take-off and landing. In addition, it is shown that the second and the third baro-inertial vertical channel damping methods are essentially complementary filters while the proposed scheme improves these complementary filters.

• Spatial Information Research
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• v.19 no.1
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• pp.13-19
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• 2011

As an urbanization is in progress, the change of the planimetric features and topography including high-rise residential buildings commonly occur. The change of the planimetric features and topography causes occurrence of the strong wind and wind speed increase or decrease due to the effect of planimetric features and topography on the windward side even though the wind blows with the same speed. In the design standard, this change by wind speed is defined as the velocity pressure exposure coefficient, the value of coefficient is estimated and reflected by ground surface roughness, but in a reality, ground surface roughness is determined in accordance with the subjective judgement of designer and then the velocity pressure exposure coefficient is estimated, moreover the research and data for classification of ground surface roughness are insufficient. In this paper, we will estimate the velocity pressure exposure coefficient by the quantified method for classifying ground surface roughness by using GIS according to the height of a building targeting area where high-rise residential buildings are built lately. When the structure subjected to wind load is designed, reasonability of design and safety of structure will be more improved by using the estimation method of velocity pressure exposure coefficient presented in this study.

• Korean Journal of Remote Sensing
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• v.20 no.4
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• pp.227-234
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• 2004

The synchronization of Time Delay and Integration (TDI) against the temporal variation of osculating altitude in the operation of high resolution satellite imager was studied. The characteristics of osculating altitude variation was analyzed and its impact on the performance of TDI imger was also investigated. A practical ]me rate control method was proposed to compensate instantaneous TDI mismatch due to the osculating altitude variation, so that geometrical performance enhancement was achieved by the proposed method. This study is applicable to real satellite operation and can be useful for satellite image quality enhancement.

• Journal of Astronomy and Space Sciences
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• v.25 no.2
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• pp.167-180
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• 2008

The resolution of Earth images taken from a satellite has close relation with satellite's altitude. If a satellite has lower altitude, it gets a picture having better resolution. However the satellite will be exposed to heavier air drag and will spend more fuel to maintain its altitude for a desired mission. Therefore, in this study, the required fuel to maintain very low earth orbit(LEO) with severe air drag is analyzed using optimization method such as collocation method. The required fuel to maintain the low altitude has significantly increased as the mission altitude is lowered and the solar activity is maximized. This study also shows that the fuel reduced by increasing the period of the satellite maneuver is very small, and that slightly increasing the satellite's mission altitude is much effective in reducing the amount of fuel to maintain its altitude. The calculated fuel to maintain very low earth orbit in this study would give useful information in planning the budget of fuel and cost for LEO satellites.