• 한국노년학
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• v.29 no.4
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• pp.1611-1628
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• 2009

It is well known that health and psychosocial factors are closely associated with depressive symptoms. Due to limitations in available data and analysis methods, however, little is known about the effects of health and psychosocial factors on depression trajectory. In order to address the limitations, this study examines the predictors of depression trajectory using latent growth curve modeling involving individuals aged 60 and over who participated in the Korean Welfare Panel Study (N=4,919). Controlling for socioeconomic variables, health and psychosocial variables were cross-sectionally associated with depressive symptoms, which is consistent with previous findings. However, the effects of health and psychosocial variables on the rate of depressive symptom change varied. Health variables were significantly associated with the levels of depressive symptoms at wave 1, but these were not significantly associated with the rate of depressive symptoms change. By contrast, although psychosocial variables were significantly associated with depressive symptoms at wave 1, the effects of psychosocial variables on the rate of depressive symptom change varied. Specifically, while self-esteem and family relationship were positively associated with the rate of depressive symptom change, social relationship was negatively associated with the rate of depressive symptom change. Based on the findings, this study discussed implications for intervention and future research.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.11a
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• pp.27-30
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• 2004

이동 객체의 위치 정보는 현재 위치뿐만이 아니라 과거 움직였던 궤적 데이터 역시 데이터마이닝과 같은 응용분야에서 중요하다. 대부분의 기존 연구에서 사용하는 GPS(Global Positioning Service) 위치정보는 이 차원 유클리디안 공간의 한 점과 시간만으로 표현된다. 우리는 이러한 표현이 가지는 내재적인 문제점들을 지적하고 이를 해결할 수 있는 새로운 방법을 제시한다. 본 논문에서 우리는 이동 객체의 움직임은 기본속도모델을 따라 움직인다고 가정하고 이틀 이용하여 다양한 움직임의 형태를 표현하고 이러한 표현에 의하여 달성할 수 있는 저장 및 처리의 효율성에 대하여 연구한다. 실제 데이터를 이용한 분석에서 우리는 이동 객체가 우리가 제시하는 속도 모델에 따라 움직인다는 사실을 보여주고, 제시하는 표현 방법이 저장뿐만이 아니라 성능적인 면에서도 기존 GPS 위치정보 표현보다 월등하다는 사실을 보여 준다.

• Korean Chemical Engineering Research
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• v.44 no.3
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• pp.294-299
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• 2006

Computational simulation was performed to analyze flow velocities and particle trajectories onto the surface of bag-shaped filters with a different permeability. When the permeability of a filter is lower than that of a low-efficient fabric bag-filter widely used, the distributions of flow velocities and particle trajectories on the filter surface were not different with decreasing the filter permeability. The distributions of streamlines and radial directional gas velocities were uniform on the filter surface except for the neighbors of the bottom edge and outlet of the filter. The particle trajectories onto filter surface were more densely distributed around the bottom edge of the filter, so that the particle number on the filter surface was maximized near the bottom edge and decreased in the direction of the filter outlet.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.5
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• pp.1495-1502
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• 1991

본 연구에서는 동일 작업 공간내에서 두대의 로봇이 각각의 토크의 제한 조건 과 충돌 회피 조건을 만족하면서 근사 최소 시간에 지정된 경로를 주행하기 위한 궤적 계획법을 제안하고자 한다. 이때, 동작 우선도에 의하여 한 대의 로봇은 주 로봇, 다른 한 대의 로봇은 종 로봇으로 지정되는데 주 로봇은 입력 토크의 제한조건을 만족 하며 주어진 경로를 최소 시간에 움직이도록 궤적 계획을 하였으며, 종 로봇은 주 로 봇과의 충돌을 피하고 입력 토크의 제한 조건을 만족하며 주어진 경로를 근사 최소 시 간에 움직이도록 하였다.

• Journal of the military operations research society of Korea
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• v.32 no.1
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• pp.176-187
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• 2006

It is difficult to estimate missile flight trajectory since a ballistic missile velocity is highly fast and has inherent behavior such as corkscrew due to unstable descending. This paper describes a comprehensive analysis of the flight trajectory characteristics of ballistic missiles. Various missile flight ranges based the comprehensive flight trajectory characteristics are derived by an analytical approach. It is shown analytically that threat due to the flight characteristics is significantly increased with reducing maximum missile ranges. This work is basic research of the establishment of operational concept for the lower tier missile defense system implementation.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.04a
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• pp.125-128
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• 2015

최근 GPS가 기본 탑재된 스마트폰이 활성화된 이후 대량의 GPS 궤적 데이터를 전자지도에 매칭하여 분석하는 요구가 대두되고 있다. 그러나 기존에 연구된 맵매칭 기법은 주로 내비게이션용 알고리즘으로 대량의 GPS궤적을 서버에서 분석하기에는 속도 및 시스템 성능의 이슈가 있다. 본 연구는 대표적인 분산 NoSQL DB인 하듐 에코시스템의 HBase를 이용한 맵매칭 시스템에 대한 연구이다. 맵매칭을 위한 전자지도를 HBase탑재하기 위한 테이블 사양을 정의하였고, HBase와 연동하여 분석하는 맵매칭 알고리즘을 제시하고 Java로 구현하여 분석하였다. 이를 통해 대량의 GPS궤적을 NoSQL 기반 방법론을 통하여 효율적으로 빅데이터를 분석하였다.

• Journal of Astronomy and Space Sciences
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• v.22 no.4
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• pp.385-392
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• 2005

We developed an algorithm to efficiently detect streaks in survey images and made a performance test with YSTAR-NEOPAT images obtained by the 0.5m telescope stationed in South Africa. Fast moving objects whose apparent speeds exceed 10 arcsec/min are the main target of our algorithm; these include artificial satellites, space debris, and very fast Near-Earth Objects. Our algorithm, based on the outline shape of elongated sources employs a step of image subtraction in order to reduce the confusion caused by dense distribution of faint stars. It takes less than a second to find and characterize streaks present in normal astronomical images of 2K format. Comparison with visual inspection proves the efficiency and completeness of our automated detection algorithm. When applied to about 7,000 time-series images from YSTAR telescope, nearly 700 incidents of streaks are detected. Fast moving objects are identified by the presence of matching streaks in adjoining frames. Nearly all of confirmed fast moving objects turn out to be artificial satellites or space debris. Majority of streaks are however meteors and cosmic ray hits, whose identity is often difficult to classify.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.5
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• pp.582-590
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• 2007

Nonlinear adaptive control of overhead cranes is investigated for anti-sway trajectory tracking with high-speed hoisting motion. The sway dynamics of two dimensional underactuated overhead cranes is heavily coupled with the trolley acceleration, hoisting rope length, and the hoisting velocity which is an obstacle in the design of decoupling control based anti-sway trajectory tracking control law To cope with this obstacle. we propose a fuzzy nonlinear adaptive anti-sway trajectory tracking control law guaranteeing the uniform ultimate boundedness of the sway dynamics even in the presence of uncertainties in such a way that it cancels the effect of the trolley acceleration and hoisting velocity on the sway dynamics. In particular. system uncertainties, including system parameter uncertainty unmodelled dynamics, and external disturbances, are compensated in an adaptive manner by utilizing fuzzy uncertainty observers. Accordingly, the ultimate bound of the tracking errors and the sway angle decrease to zero when the fuzzy approximation errors decrease to zero. Finally, numerical simulations are performed to confirm the effectiveness of the proposed scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.10
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• pp.1879-1885
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• 2017

This paper discusses the trajectory tracking system of unmanned ground vehicles based on predictive control. Because the unmanned ground vehicles can not satisfactorily complete the path tracking task, highly efficient and stable trajectory control system is necessary for unmanned ground vehicle to be realized intelligent and practical. According to the characteristics of unmanned vehicle, this paper built the kinematics tracking models firstly. Then studied algorithm solution with the tools of the optimal stability analysis method and proposed a tracking control method based on the model predictive control. The controller used a kinematics-based prediction model to calculate the predictive error. This controller helps the unmanned vehicle drive along the target trajectory quickly and accurately. The designed control strategy has the true robustness, simplicity as well as generality for kinematics model of the unmanned vehicle. Furthermore, the computer Simulink/Carsim results verified the validity of the proposed control method.

• Aerospace Engineering and Technology
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• v.12 no.1
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• pp.173-181
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• 2013

In this paper, the design result of the trajectory-based air traffic analysis software which is going to be used to assess air-traffic efficiency in case that some modification's made in dynamic airspace configuration, is described. The software has been developed to make statistical data about air-traffic in Incheon FIR based on the RPL, and to analyze the airway utilization and controller workload using the trajectory modeling data which are derived from the aircraft type, cruise speed, cruise altitude, and routes and fixes in the RPL. Since it batch-processes the long-term trajectory data with other inputs such as airspace, route information and so on, it has the advantage of quickly predicting the traffic variation when some change in airspace and route information is made.