• 제어로봇시스템학회논문지
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• 제15권10호
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• pp.1047-1055
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• 2009

Since nuclear and chemical materials could damage people and disturb battlefield missions in a wide region, nuclear/chemical reconnaissance systems utilizing multiple mobile robots are highly desirable for rapid and safe reconnaissance. In this paper, we design a nuclear/chemical reconnaissance system including mobile robots. Also we propose time-efficient trajectory planning algorithms using grid coverage and contour finding methods for reconnaissance operation. For grid coverage, we performed in analysis on time consumption for various trajectory patterns generated by straight lines and arcs. We proposed BCF (Bounded Contour Finding) and BCFEP (Bounded Contour Finding with Ellipse Prediction) algorithms for contour finding. With these grid coverage and contour finding algorithms, we suggest trajectory planning algorithms for single, two or four mobile robots. Various simulations reveal that the proposed algorithms improve time-efficiency in nuclear/chemical reconnaissance missions in the given area. Also we conduct basic experiments using a commercial mobile robot and verify the time efficiency of the proposed contour finding algorithms.

• 제어로봇시스템학회논문지
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• 제8권10호
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• pp.890-897
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• 2002

This paper deals with the reduction of trajectory tracking error by changing the initial postures of a biped robot. Gait of a biped robot depends on the constraints of mechanical kinematics and the initial states including the posture. Also the dynamic walking stability in a biped robot system is analyzed by zero moment point(ZMP) among the stabilization indices. Path trajectory, in which knee joint is bent forward like human's cases, is applied to most cases considered with above conditions. A new initial posture, which is similar to bird's gait, is proposed to decrease trajectory tracking error and it is verified through real experimental results.

• 한국항공운항학회지
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• 제30권4호
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• pp.1-8
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• 2022

In this study, we propose trajectory-based arrival management using CDO (Continuos Descent Operations). The operational procedures with TBO (Trajectory-Based Operations) concept were established to allow aircraft and ground system to share the trajectories with each other in real time. The proposed operational concept was validated in the air traffic control simulation environment, which consists of controller working position, pseudo pilot system, air traffic generation system, and controllers' decision support system for arrival management using CDO. Simulation results compared with actual flight data indicate that proposed concept could improve the efficiency of traffic flow management in terms of total descending time and fuel consumption. And it was confirmed that if there is a system that can share and utilize the synchronized trajectory, it can be helpful to control arrival aircraft and apply CDO concept.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.77-78
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• 2023

As large logistics buildings have high floor heights and long spans, these buildings are designed as PC structures, and large cranes are used to lift PC members. PC erection planning can generally cause errors depending on the field engineer's experience. To solve this problem, a basic analysis method is needed to establish a systematic PC member erection plan. Crane work can be minimized if the trajectory is easily and quickly calculated according to the location of the crane and applied to the site. Therefore, the objective of this study is a basic study of crane trajectory distance calculation for sustainable PC members erection of large logistic building. In this study, a crawler crane commonly used for lifting PC members is limited. The trajectory distance for the PC erection plan was automatically calculated using the algorithm.

• 한국항공우주학회지
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• 제38권10호
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• pp.998-1011
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• 2010

본 연구에서는 미래 한국의 달탐사에 대비, 제한추력을 이용한 최적의 지구-달 천이궤적 설계를 수행하였다. 보다 실제적인 임무 시나리오 설계를 위해 달 천이 (Trans Lunar Injection, TLI) 기동에 사용되는 발사체 상단 킥모터의 추력 성능을 제한하였다. 이를 바탕으로 지구 출발부터 달 근접에 이르는 지구-달 천이비행궤적이 설계되었으며, 제한추력을 이용하여 설계된 비행 궤적의 최적화 결과와 순간추력을 이용하여 최적화된 결과가 비교 분석되었다. 만약 순간추력을 이용해 도출된 예비 임무 설계의 결과가 제한추력을 가정한 임무 설계를 위해 응용될 경우, 가정된 제한추력의 크기에 따라 다양한 범위의 기동량의 차이가 발생 할 수 있어 이에 따른 충분한 고려가 이루어져야 함을 확인하였다. 본 연구에서 제시된 제한추력을 이용한 달탐사 임무궤적 설계/해석 결과는 미래 한국의 달탐사를 대비하는데 있어 다양한 사전 지식을 제공할 것이며 장차 상세한 임무설계를 위한 알고리즘의 기반으로 사용될 수 있다.

• 한국항공우주학회지
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• 제46권1호
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• pp.41-51
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• 2018

무장 헬리콥터에서 발사되는 무유도 로켓은 로터 블레이드에 의한 내리흐름과 전후좌우 기동으로 인한 외풍에 의해 전체 궤적 및 사거리가 변화하므로, 내리흐름 효과를 고려하여 무유도 로켓의 궤적을 예측하는 것이 중요하다. 내리흐름 효과를 고려한 무유도 로켓의 궤적 및 사거리를 예측하기 위해, 본 연구에서 여러 외풍 조건에 따른 후류 영역을 Actuator Disk Model(ADM)로 계산하고 6 자유도 (6 DOF) 운동 해석으로 무유도 로켓의 자세 및 전체 비행 궤적을 예측할 수 있는 알고리즘을 개발하였다. 개발된 알고리즘은 ADM 해석 결과를 6 자유도에 반영하여 다양한 초기 발사조건에서 무유도 로켓의 전체 궤적을 예측할 수 있고, 기존 Inflow model을 이용한 내리흐름 해석과는 다르게 동체와의 간섭효과를 고려하여 비교적 정확한 내리흐름 및 다양한 외풍 환경 조건으로 궤적을 예측 할 수 있다. 개발된 알고리즘을 이용하여, 내리흐름 효과에 의한 무유도 로켓의 자세 및 궤적 변화 메커니즘을 유효 받음각 변화와 기수 자세 안정성으로 규명하였다. 그리고 외풍으로 인해 변화하는 내리흐름 효과를 고려하여 무유도 로켓의 궤적변화와 사거리를 계산한 결과, 후방 외풍 시 최대 13% 사거리 증가를 보였다. 사거리 증가의 주요 요인으로 내리흐름 영역과 강도, 부차적 요인으로 외풍과 동체와의 간섭효과, 동압의 크기인 것을 밝혔다. 또한 사거리 변화량이 가장 큰 후방 외풍에서, 후방 외풍의 풍속이 증가함에 따라 로켓의 사거리가 증가하였다. 하지만 특정 후방 외풍 크기 이상에서 더 이상 로켓 사거리가 증가하지 않는 한계를 보였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 신호처리소사이어티 추계학술대회 논문집
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• pp.53-56
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• 2003

In this paper, we propose a new method which generates the trajectory of the mouth shape for the characters by the user inputs. It is based on the character at a basis syllable and can be suitable to the mouth shape generation. In this paper, we understand the principle of the Korean language creation and find the similarity for the form of the mouth shape and select it as a basic syllable. We also consider the articulation of this phoneme for it and create a new mouth shape trajectory and apply at face of an 3D avatar.

• Journal of Mechanical Science and Technology
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• 제20권10호
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• pp.1557-1566
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• 2006

We present a procedure for the application of global orthogonal polynomial into an atmospheric re-entry maneuvering problem. This trajectory optimization is imbedded in a family of canonically parameterized optimal control problem. The optimal control problem is transcribed to nonlinear programming via global orthogonal polynomial and is solved a sparse nonlinear optimization algorithm. We analyze the optimal trajectories with respect to the performance of re-entry maneuver.

• Journal of Power Electronics
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• 제16권2호
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• pp.584-597
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• 2016

This paper focuses on an improvement in the transient performance of Boost converters when the load changes abruptly. This is achieved on the basis of the nature trajectory in Boost converters. Three key aspects of the transient performance are analyzed including the storage energy change law in the inductors and capacitors of converters during the transient process, the ideal minimum voltage deviation in the transient process, and the minimum voltage deviation control trajectory. The changing relationship curve between the voltage deviation and the recovery time is depicted through analysis and simulations when the load suddenly increases. In addition, the relationship curve between the current fluctuation and the recovery time is obtained when the load suddenly decreases. Considering the aspects of an increasing and decreasing load, this paper proposes the transient performance synthetic optimized trajectory and control laws. Through simulation and experimental results, the transient performances are compared with the other typical three control methods, and the ability of proposed synthetic trajectory and control law to achieve optimal transient performance is verified.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.742-748
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• 2004

In this paper are presented TSTO system analysis including some controlled variables on the engine operation such as a fuel flow rate and a pressure ratio of compressor, as well as variables on the trajectory. TSTO studied here is accelerated up to Mach 6 by a fly-back booster powered by air breathing engines. Three different types of engine cycle were treated for propulsion system of the booster, such as a turbo ramjet, a precooled turbojet and an EXpander cycle Air Turbo Ramjet (ATREX). The history of the controlled variables on the engine operation was optimized by Sequential Quadratic Programming (SQP) to accomplish the minimum fuel consumption. The trajectory was also optimized simultaneously. The results showed that the turbo ramjet gave the best fuel consumption. The optimal trajectory was almost the same except in the transonic range and just before reaching to Mach 6. The history of the pressure ratio of compressor considerably depended on the engine type. It is concluded that simultaneous optimization for engine control and trajectory is effective especially for a high-speed airplane propelled by turbojets like the TSTO booster.