• 한국추진공학회지
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• 제12권3호
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• pp.60-67
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• 2008

본 연구는 운용중인 항공기의 가스터빈엔진을 유전 알고리즘을 이용한 실시간 결함진단을 통해 엔진 운용의 안정성과 신뢰성을 확보하는 것이 목적이다. 대상엔진인 터보샤프트엔진의 구성품 중 성능 저하는 압축기, 가스발생기 터빈, 동력 터빈 중 한 구성품에서만 발생한다고 가정하였다. 설계점에 비해 탈 설계영역에서의 학습 데이터는 약 200배 이상으로 증가하였으며, 따라서 요구 수렴도를 만족시키기 위한 방대한 학습시간이 요구된다. 진단오차를 만족시키고 학습시간을 단축시키기 위해 최적분할을 사용하였고 그 결과, 오차범위 5% 이내로 진단됨을 확인하였다.

• Journal of Astronomy and Space Sciences
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• 제32권3호
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• pp.257-268
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• 2015

Characteristics of delta-V requirements for deploying an impactor from a mother-ship at different orbital altitudes are analyzed in order to prepare for a future lunar CubeSat impactor mission. A mother-ship is assumed to be orbiting the moon with a circular orbit at a 90 deg inclination and having 50, 100, 150, 200 km altitudes. Critical design parameters that are directly related to the success of the impactor mission are also analyzed including deploy directions, CubeSat flight time, impact velocity, and associated impact angles. Based on derived delta-V requirements, required thruster burn time and fuel mass are analyzed by adapting four different miniaturized commercial onboard thrusters currently developed for CubeSat applications. As a result, CubeSat impact trajectories as well as thruster burn characteristics deployed at different orbital altitudes are found to satisfy the mission objectives. It is concluded that thrust burn time should considered as the more critical design parameter than the required fuel mass when deducing the onboard propulsion system requirements. Results provided through this work will be helpful in further detailed system definition and design activities for future lunar missions with a CubeSat-based payload.

• 한국농공학회논문집
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• 제58권5호
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• pp.29-37
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• 2016

Unmanned Aerial Vehicle (UAV) have several advantages over conventional remote sensing techniques. UAV can acquire high-resolution images quickly and repeatedly with a comparatively lower flight altitude i.e. 80~400 m nullifying the effect of extreme weather and cloud. This study discussed the use of low cost-effective UAV based remote sensing application in inspection of agricultural subsidy. The study area accrue $60.5km^2$ of Buljeong-myeon, Goesan-gun, Chungbuk in South Korea. UAV image acquired 25 times from July 25 to August 11, 2015 for 3 days. It is observed that almost 81.1 % (3,571 of 4,410 parcels) parcels are truthful whereas some parcels are incorrect or fraudulent. Surveying with UAV for agricultural subsidy instead of field stuff can reduce the required time as much as 64.8 % (19 of 54 days). Therefore, it can contribute significantly in speedy and more accurate processing of grant application and can end unfair receipt of the grant which in turn will improve customer satisfaction.

• 한국농공학회논문집
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• 제57권6호
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• pp.91-97
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• 2015

The Unmanned Aerial Vehicles (UAVs) have several advantages over conventional RS techniques. They can acquire high-resolution images quickly and repeatedly. And with a comparatively lower flight altitude i.e. 80~400 m, they can obtain good quality images even in cloudy weather. Therefore, they are ideal for acquiring spatial data in cases of small agricultural field with mixed crop, abundant in South Korea. This paper discuss the use of low cost UAV based remote sensing for classifying crops. The study area, Gochang is produced by several crops such as red pepper, radish, Chinese cabbage, rubus coreanus, welsh onion, bean in South Korea. This study acquired images using fixed wing UAV on September 23, 2014. An object-based technique is used for classification of crops. The results showed that scale 250, shape 0.1, color 0.9, compactness 0.5 and smoothness 0.5 were the optimum parameter values in image segmentation. As a result, the kappa coefficient was 0.82 and the overall accuracy of classification was 85.0 %. The result of the present study validate our attempts for crop classification using high resolution UAV image as well as established the possibility of using such remote sensing techniques widely to resolve the difficulty of remote sensing data acquisition in agricultural sector.

• International Journal of Aerospace System Engineering
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• 제2권2호
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• pp.29-33
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• 2015

The multidisciplinary design optimization (MDO) of a launch vehicle (LV) with a hybrid rocket engine (HRE) was carried out to investigate the ability of an HRE for a single-stage LV. The non-dominated sorting genetic algorithm-II (NSGA-II) was employed to solve two design problems. The design problems were formulated as two-objective cases involving maximization of the downrange distance over the target flight altitude and minimization of the gross weight, for two target altitudes: 50.0 km and 100.0 km. Each objective function was empirically estimated. Several non-dominated solutions were obtained using the NSGA-II for each design problem, and in each case, a trade-off was observed between the two objective functions. The results for the two design problem indicate that economical performance of the LV is limited with the HRE in terms of the maximum downrange distances achievable. The LV geometries determined from the non-dominated solutions were examined.

• 제어로봇시스템학회논문지
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• 제11권8호
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• pp.726-732
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• 2005

This paper proposes an autolanding guidance and control algorithm with the lateral guidance law. This algorithm is basically formulated and designed in feedback linearization based on singular perturbation. Main features of this algorithm are two facts. One of those is that when a certain situation happens that airplane must realign to the runway suddenly assigned due to unexpected environment change around the landing site, the heading guidance in this algorithm is very valuable, and the other is the fact that the inner loop control of this algorithm is able to be designed directly based on the Handling Quality Requirements that most flight control systems must be satisfied with. To illustrate the potential of this algorithm, 6-DOF nonlinear simulation based on the nonlinear airplane model shown in Ref.[11] is carried out. The simulation results showed that the altitude response to the given landing trajectory is accurate, and the airplane heading alignment to the assigned runway from the lateral deviation is successful. It is noted that this algorithm is also applicable to unmanned aerial vehicle, which can be retrieved in autolanding technique, where the runway far retrieving the vehicle is in any direction for example at war field.

• 항공우주기술
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• 제12권1호
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• pp.173-181
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• 2013

본 논문에서는 동적 공역 형상 관리상의 변경이 발생할 때에 대한 항공 교통 효율성 평가에 사용될 궤적기반 항공 교통량 분석 소프트웨어의 설계 결과를 기술한다. 본 소프트웨어는 비행계획서에 기초한 인천 FIR의 항공 교통에 대한 통계 자료를 산출하고, 비행계획서 상의 항공기 종류, 순항고도, 속도, 이동 경로 등으로부터 도출된 궤적 모델링 자료를 이용하여 항공로 이용율, 관제사 관제량을 분석하도록 설계되었다. 공역 설계 및 항공로 입력 정보와 함께 장기간에 걸친 궤적 모델링 자료를 한꺼번에 입력받아 일괄 처리하는 방식을 적용함에 따라, 본 소프트웨어는 공역 및 항공로 등의 수정 내용에 따른 교통량 변화를 빠르게 예측할 수 있는 장점을 가진다.

• 한국항공운항학회지
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• 제23권3호
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• pp.42-52
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• 2015

Since the tax-free system for overseas laborers was implemented in 1974, the tax-free limits of international air crew, overseas construction workers and crewmen of deep-sea fishing ships and ocean-going ships had been identical by 2005, but there are big differences, currently. The Ministry of Strategy and Finance pointed out the poor working environments and international competitiveness of the industries to explain the reason for the differential tax-free limit. From this perspective, the fairness of the tax-free system for overseas laborers was analyzed. This is an empirical study, based on the objective fact. The study finding showed that international air crew were working in the structural flight work environments to threaten the right of health due to jet lag and excessive exposure to high-altitude cosmic radiation. Therefore, it was analyzed there should be a proper system reform to apply the tax-free limits to international air crew which are identical to those applied to overseas construction workers and crewmen of deep-sea fishing ships and ocean-going ships, for a fair taxation.

• 한국군사과학기술학회지
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• 제15권4호
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• pp.424-434
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• 2012

This paper presents a path planning algorithm of the unmanned aerial vehicle for the neutralization of the enemy firepower. The long range firepower of the ememy is usually located at the rear side of the mountain which is difficult to bomb. The path planner not only consider the differential constraints of the Unmanned Aerial Vehicle (UAV) but also consider the final approaching angle constraint. This problem is easily solved by incorporating the analytical upper bounded continuous curvature path smoothing algorithm into the Rapidly Exploring Random Tree (RRT) planner. The proposed algorithm can build a feasible path satisfying the kinematic constraints of the UAV on the fly. In addition, the curvatures of the path are continuous over the whole path. Simulation results show that the proposed algorithm can generate a feasible path of the UAV for the bombing mission regardless of the posture of the tunnel.

• 한국조경학회지
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• 제17권3호
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• pp.1-8
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• 1990

The digital terrain model (DTM) or digital elevation model (DEM) is commonly used in representing the continuous variation of relief over space. One of the most frequent applications is to display the three dimensional view of the landform concerned. In this paper, the altitude matrices-regular grid cell format of the elevation in Mt. Kyeryong National Park were used in developing the three dimensional view software for the first time in Korea. It required the removal of hidden lines or surfaces. To do this, it was necessary to identify those surfaces and line segments that are visible and those that are invisible. Then, only the visible portions of the landform were displayed. The assumption that line segments are used to approximate contour surfaces by polygons was used in developing the three dimensional orthographic view. In order to remove hidden lines, the visibility test and masking algorithms were used. The software was developed in the engineering workstation, SUN 3/280 at the Institute of Space Science and Astronomy using 'C' in UNIX operating system. The software developed in this paper can be used in various fields. Some of them are as follows : (1) Landscape design and planning for identifying viewshed area(line of sight maps) (2) For planning the route selection and the facility location (3) Flight simulation for pilot training (4) Other landscape planning or civil engineering purposes