• International Journal of Aeronautical and Space Sciences
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• v.18 no.2
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• pp.344-351
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• 2017

This paper presents a method to estimate steady wind and airspeed bias error using an aircraft with GPS and airspeed sensor. The estimation uses the vector relation between the inertial, air, and wind velocities through a novel design of an extended Kalman filter. The observability analysis is also presented to show that the aircraft is required to keep changing its flight direction for the desired observability. The feasibility and performance of the proposed algorithm is demonstrated through simulations and flight experiments.

• Journal of Advanced Marine Engineering and Technology
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• v.14 no.4
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• pp.67-71
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• 1990

The traditional finite element method applied to dynamic problems employs shape functions which are based on a static displacement assumption. The more exact approach uses frequency-dependent shape functions and frequency-dependent mass and stiffness matrices. Such matrices are developed for a torsional vibration of shaft element. Numerical examples are presented for a cantilever beam.

• The Journal of the Acoustical Society of Korea
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• v.15 no.1E
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• pp.84-88
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• 1996

In this paper, we propose a novel adaptive digital filter for tonal noise cancellation, with a frequency tracking capability. The proposed algorithm not only estimates the magnitude and phase of the tonal disturbance but also tracks its frequency, which changes in quasi-static manner. The algorithm uses the steepest descent method and the instantaneous frequency approach for the phase/magnitude estimation and frequency tracking, respectively. A number of computer simulations have been carried out in order to demonstrate the feasibility of the proposed ANC algorithm under various conditions.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.7
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• pp.48-55
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• 1998

We propose a new static current source model and parameter extraction method for AlGaAs/GaAs HBT. The proposed model has 9 parameters describing internal currents and are experessed with the physically meaningful parameters.The proposed parameter extraction method uses the measured dC IV curves and does not need the gummel plt data and any optimization process. the constructed model based on the proposed method predicts the measured data well.

• Proceedings of the Acoustical Society of Korea Conference
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• 1995.06a
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• pp.184-187
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• 1995

This paper proposes an algorithm for machine recognition of phonemes in continuous speech. The proposed algorithm is static strategy neural network. The algorithm uses, at the stage of training neuron, features such as PARCOR coefficient and auditory-like perceptual liner prediction . These features are extracted from speech samples selected by a sliding 25.6msec windows with s sliding gap being 3 msec long, then interleaved and summed up to 7 sets of parmeters covering 171 msec worth of speech for use of neural inputs. Perfomances are compared when either PARCOR or auditory-like PLP is included in the feture set.

• Journal of Positioning, Navigation, and Timing
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• v.5 no.1
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• pp.21-28
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• 2016

The Wide Area Differential Global Positioning System (WADGPS) that uses a number of Global Navigation Satellite System (GNSS) reference stations are implemented with various types and provide services as it can service a wide range of areas relatively. This paper discusses a constellation design of reference stations and performance analysis of the WADGPS. It presented performance results of static and dynamic users when wide area correction algorithm was applied using eight reference stations.

• Journal of Korean Society for Geospatial Information Science
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• v.22 no.4
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• pp.127-133
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• 2014

The purpose of this study is to evaluate the accuracy of Network-RTK(VRS) survey for applying to Ground Control Points(GCPs) survey required for mapping aerial photographs. Network-RTK has been serviced by National Geographic Information Institute since 2007. On the basis of the global coordinates system(ITRF2000), the coordinates of GCPs determined by Static GNSS survey with relative positioning techniques were regarded as accurate values. The coordinates of GCPs were also determined by Network-RTK survey using two kinds of receivers, and then they were converted into the global coordinates system(ITRF2000) by applying suitable geoid model and coordinate transformation. These coordinates of GCPs were compared with those from Static GNSS survey. The root mean squares error (RMSE) of coordinate differences between Network-RTK and Static GNSS was ${\pm}2.0cm$ in plane and ${\pm}7.0cm$ in height. Therefore, Network-RTK survey that enables single GNSS receiver to measure positions in short time is a practical alternative in positioning GCPs to either RTK survey that uses more than two sets of GNSS receivers or Static GNSS survey that requires longer observation time.

• Journal of Internet Computing and Services
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• v.8 no.3
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• pp.119-129
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• 2007

To recognition a human motion, in this paper, we propose a neural approach using silhouettes in video frames captured by two cameras placed at the front and side of the human body. To extract features of the silhouettes for motion estimation, the proposed system computes both global and local features and then groups these features into static and dynamic features depending on whether features are in a static frame. Extracted features are in a static frame. Extracted features are used to train a RBF network. The neural system uses static features as the input of the neural network and dynamic features as additional features for recognition. In this paper, the proposed method was applied to movement education for young children. The basic movements for such education consist of locomotor movements, such as walking, jumping, and hopping, and non-locomotor movements, including bending, stretching, balancing and turning. The system demonstrated the effectiveness of motion recognition for movement education generated by the proposed neural network. The proposed system dan be extended to the system for movement education which develops the spatial sense of young children.

• Tribology and Lubricants
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• v.34 no.3
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• pp.75-83
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• 2018

Microturbomachinery (< 250 kW) using gas foil bearings can function without oil lubricants, simplify rotor-bearing systems, and demonstrate excellent rotordynamic stability at high speeds. State-of-the-art technologies generally use bump foil bearings or leaf foil bearings due to the specific advantages of each of the two types. Although these two types of bearings have been studied extensively, there are very few studies on leaf-bump foil bearings, which are a combination of the two aforementioned bearings. In this work, we illustrate a simple mathematical model of the leaf-bump foil bearing with leaf foils supported on bumps, and predict its static and dynamic performances. The analysis uses the simple elastic model for bumps that was previously developed and verified using experimental data, adds a leaf foil model, and solves the Reynolds equation for isothermal, isoviscous, and ideal gas fluid flow. The model predicts that the drag torques of the leaf-bump foil bearings are not affected significantly by static load and bearing clearance. Due to the preload effect of the leaf foils, rotor spinning, even under null static load, generates significant hydrodynamic pressure with its peak near the trailing edge of each leaf foil. A parametric study reveals that, while the journal eccentricity and minimum film thickness decrease, the drag torque, direct stiffness, and direct damping increase with increasing bump stiffness. The journal attitude angle and cross-coupled stiffness remain nearly constant with increasing bump stiffness. Interestingly, they are significantly smaller compared to the corresponding values obtained for bump foil bearings, thus, implying favorable rotor stability performance.

• Environmental and Resource Economics Review
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• v.12 no.2
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• pp.299-325
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• 2003

This study uses Conrad's model(nominal fishing effort) of a fishery to analyze theoretically the effects of cost changes on fishing effort, harvest level, and stock size. Static and dynamic open access effects are also modeled present value maximizing scenarios through simulations, and compared an extended model, Cunningham's model(diminishing fishing effort). Results show that an increase in the unit cost of effort goes up the fish stock in static open access, but open access dynamics shows the exhaustion of fish stock as the unit cost of effort decreases. In conclusion, we can derive the optimal equilibrium of resource, given conditions and parameters, as well as utilize this comparative statics to efficient fishery management.