• Advances in aircraft and spacecraft science
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• v.7 no.1
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• pp.1-17
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• 2020

In this paper, a new model-based Fault Detection and Diagnosis (FDD) method for an agile supersonic flight vehicle is presented. A nonlinear model, controlled by a classical closed loop controller and proportional navigation guidance in interception scenario, describes the behavior of the vehicle. The proposed FDD method employs the Inertial Navigation System (INS) data and nonlinear dynamic model of the vehicle to inform fins damage to the controller before leading to an undesired performance or mission failure. Broken, burnt, unactuated or not opened control surfaces cause a drastic change in aerodynamic coefficients and consequently in the dynamic model. Therefore, in addition to the changes in the control forces and moments, system dynamics will change too, leading to the failure detection process being encountered with difficulty. To this purpose, an equivalent aerodynamic model is proposed to express the dynamics of the vehicle, and the health of each fin is monitored by the value of a parameter which is estimated using an adaptive robust filter. The proposed method detects and isolates fins damages in a few seconds with good accuracy.

• Journal of Korea Multimedia Society
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• v.21 no.6
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• pp.698-704
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• 2018

When the new ammunition is designed, it is necessary to confirm in advance how long the target distance is depends on the shape and weight of the designed ammunition. Therefore we can use commercial software such as PRODAS to predict the target distance in the design stage. This commercial software has aerodynamic data for various ammunition shape and calculates the target range by calculating the kinetic equations of the ammunition using the aerodynamic data most similar to the designed ammunition. The ammunition for predicting the target distance through software such as PRODAS is a non-guided ammunition that has no control after launch but the glide type ammunition is guided and control ammunition. So it is predicts the state of ammunition after the launch. A new type of simulator is needed to analyze the maximum range and to verify the onboard guided and control algorithm. The simulator constructed in this paper is an optimized simulator for glide type ammunition. Unlike unmanned aircraft and guided missiles. The rotation characteristics of the ammunition are considered and the navigation initialization algorithm is applied. The constructed simulator confirmed the performance by performing maximum range analysis of glide type ammunition.

• Journal of Wetlands Research
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• v.7 no.1
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• pp.93-106
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• 2005

This article is based on the findings of problems and limits in implementing integrated coastal management strategy in Shihwa Lake area to develop management framework, mechanisms and processes that insure the participation of various stakeholders in making decisions for sustainable development of reclaimed land. The project performance of the Shihwa Comprehensive Management Plan for Water Quality and Environment Restoration formulated in 2001 was evaluated and reviewed to give some valuable guidance for reducing the wide gap between integrated planning and implementation. Managing inter-sectoral conflicts among future land uses in Shihwa reclaimed area is one of the most important issues to make progress in integrated coastal management. There is a urgent need of developing scientific decision-supporting tools for evaluating the alternative scenarios as well as capacity building programs for local stakeholders.

• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.720-731
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• 2014

There are many kinds of optical systems to widen a field of view. Fisheye lenses with view angles of 180 degrees and omni-directional systems with the view angles of 360 degrees are recognized as proper systems to widen a field of view. In this study, we proposed a new optical system to overcome drawbacks of conventional omni-directional systems such as a limited field of view in the central area and difficulties in manufacturing. Thus we can eliminate the undesirable reflection components of the omni-directional system and solve the primary drawback of the conventional system. Finally, tolerance analysis using Zernike polynomial coefficients was performed to confirm the productivity of the new optical system. Furthermore, we established a method of optical axis alignment and compensation schemes for the proposed optical system as a result of tolerance analysis. In a sensitivity calculation, we investigated performance degradation due to manufacturing error using Code V(R) macro function. Consequently, we suggested compensation schemes using a lens group decentering. This paper gives a good guidance for the optical design and tolerance analysis including the compensation method in the extremely wide angle system.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2526-2531
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• 2005

A practical pinch torque estimator based on the Kalman filter is proposed for low-cost anti-pinch window control systems. To obtain the accurate angular velocity from Hall-effect sensor measurements, the angular velocity calculation algorithm is executed with additional procedures for removing the measurement noises. Apart from the previous works using the angular velocity estimates and torque estimates for detecting the pinched condition, the torque rate is augmented to the system model and the proposed pinch estimator is derived by applying the steady-state Kalman filter recursion to the model. The motivation of this approach comes from the idea that the bias errors in torque estimates due to the motor parameter uncertainties can be almost eliminated by introducing the torque rate state. For detecting the pinched condition, a systematic way to determine the threshold level of the torque rate estimates is also suggested via the deterministic estimation error analysis. Simulation results are given to certify the pinch detection performance of the proposed algorithm and its robustness against the motor parameter uncertainties.

• Journal of The Korean Digital Architecture Interior Association
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• v.13 no.2
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• pp.5-16
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• 2013

With regard to the new town developments which have supplied lots of houses in a short period of time in Korea this study aims to evaluation and finding out problems of the developments finally to suggest the direction. A new town's competitiveness model set in the previous paper takes a role of research frame to recognize the problems and to show the direction. The model explains that new town's competitiveness is composed of 4 factors; Self-sufficiency, Innovativenss, Identity and Sustainability. Problems of the developments are as follows; incongruity of spatial structure especially in the capital region, deficiency of self-sufficiency resulted from single-use development, restriction on mixed development by a number of regulations in capital region, low business value, grand scale of land compensation, house oriented planning guidance, unfair share of infrastructure fee, and physical structure depending mainly on fossil energy. Based on this recognition this study conclusively suggests corresponding direction such as role performance as a means of urban growth management, promotion of quality of life by accumulating social capital, introduction of socially sustainable management program for the new towns, discovery and creation of town's value, reexamination of self-sufficiency's meaning or target, selective deregulation of metropolitan development, institutional strategy for cost reduction, changeover from house index to urban function oriented index, and pursuit of low-carbon green town.

• Current Industrial and Technological Trends in Aerospace
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• v.8 no.1
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• pp.62-76
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• 2010

In this paper, recent researches about the unmanned lunar lander development are studied. Objectives of this study are to derive research trends and to identify key design activities especially in early design phase of unmanned lunar lander. Case study covers SELENE-2 of Japan, LEDA and MoonNEXT of ESA, and small and modular spacecraft approach of NASA. Lunar lander concepts proposed for the International Lunar Network Anchor Nodes are also studied. For each lunar lander program, mission requirements are summarized and mission design results are reviewed. Approaches of safe lunar landing including design of navigation, guidance and control, combination of sensors, derived sensor and propulsion performance requirements are also analyzed.

• Asia pacific journal of information systems
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• v.12 no.1
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• pp.139-158
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• 2002

As the telecommunication market becomes mature in Korea, severe competition has already begun on the market. While service providers struggled for the last couple of years to acquire as many new customers as possible, nowadays they are making more efforts on retaining the current customers. The churn management by analyzing customers' demographic and transactional data becomes one of the key customer retention strategies which most companies pursue. However, the customer data analysis has still remained at the basic level in the industry, even though it has considerable potential as a tool for understanding customer behavior. This paper develops several churn prediction models using data mining techniques such as logistic regression, decision trees, and neural networks. For model-building, real data were used which were collected from one of the major telecommunication companies in Korea. This paper explores various ways of comparing model performance, while the hit ratio was mainly focused in the previous research. The comparison criteria used in this study include gain ratio, Kolmogorov-Smirnov statistics, distribution of the predicted values, and explanation ability. This paper also suggest some guidance for model selection in applying data mining techniques.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.8
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• pp.3399-3419
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• 2020

In the Vehicular Ad-hoc Network (VANET), the data transmission of time-sensitive applications requires low latency, such as accident warnings, driving guidance, etc. However, frequent changes of topology in VANET will result in data transmission failures. In order to improve the efficiency of VANETs data transmission and increase the timeliness of data, this paper proposes a relay scheme based on Recurrent Neural Network (RNN) trajectory prediction, which can be used to select the optimal relay vehicle to transmit data. The proposed scheme learns vehicle trajectory in a distributed manner and calculates the predicted trajectory, and then the optimal vehicle can be selected to complete the data transmission, which ensures the timeliness of the data. Finally, we carry out a set of simulations to demonstrate the performance of the algorithm. Simulation results show that the proposed scheme enhances the timeliness of the data and the accuracy of the predicted driving trajectory.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.4
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• pp.112-120
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• 2005

The solid propellants have been most widely used for the military rockets or missiles all over the world and the efforts have been focused on the enhancement of propellant performance up to 1980s. lately in company with the distinguished development in the intelligence and communication technology, the more accurate guidance as well as maneuverability has been required in the military weapon system. To meet the requirements such as a high maneuverability, insensitiveness, or stealth of missile, the researches have been doing to develop the solid propellants which have a quality of ultra-fast burning rate, insensitiveness, low signature or the like.