단일 크랙을 갖는 외팔보의 진동특성

Journal of the Korean Society for Aeronautical & Space Sciences, 2012

This paper describes on the aerodynamic characteristics of the first domestically manufactured aircraft, Buhwalho, in Korea. The computational fluid dynamics(CFD) calculations and wind tunnel test were utilized to investigate the basic aerodynamic characteristics of aircraft with control surface deflections and attitude changes. Variations of lift, drag and pitching moment due to angles of attack and control surface deflections were analyzed and also flight stability due to side force, yawing and rolling moments caused by the change of sideslip angles, rudder and aileron deflections were discussed. Through this study, the meaningful aerodynamic data by CFD calculations and wind tunnel tests were obtained and the flight characteristics based on these data were confirmed accordingly by the flight tests.

Journal of Korean navigation and port research, 2006

Journal of the Institute of Electronics Engineers of Korea, 2013

We propose adaptive detection algorithm to reduce a false alarm by considering the characteristics of the random noise on the detection system based on a seismic sensor. The proposed algorithm consists of the first step detection using kernel function and the second step detection using detection classes. Kernel function of the first step detection is obtained from the threshold of the Neyman-Pearon decision criterion using the probability density functions varied along the noise from the measured signal. The second step detector consists of 4 step detection class by calculating the occupancy time of the footstep using the frist detected samples. In order to verify performance of the proposed algorithm, the detection of the footsteps using measured signal of targets (walking and running) are performed experimentally. The detection results are compared with a fixed threshold detector. The frist step detection result has the high detection performance of 95% up to 10m area. Also, the false alarm probability is decreased from 40% to 20% when it is compared with the fixed threshold detector. By applying the detection class(second step detector), it is greatly reduced to less than 4%.

The Journal of Korea Robotics Society, 2011

Global positioning system (GPS) is widely used to measure the position of a vehicle. However, the accuracy of the GPS can be severely affected by surrounding environmental conditions. To deal with this problem, the GPS and odometry data can be combined using an extended Kalman filter. For stable navigation of an outdoor mobile robot using the GPS, this paper proposes two methods to evaluate the reliability of the GPS data. The first method is to calculate the standard deviation of the GPS data and reflect it to deal with the uncertainty of the GPS data. The second method is to match the GPS data to the traversability map which can be obtained by classifying outdoor terrain data. By matching of the GPS data with the traversability map, we can determine whether to use the GPS data or not. The experimental results show that the proposed methods can enhance the performance of the GPS-based outdoor localization.

Transactions of the Korean Society for Noise and Vibration Engineering, 2022

The vibration characteristics of bolted structures change depending on the bolt's clamping force. This can be used to detect bolt looseness or to evaluate structural integrity. In this study, the vibration characteristics based on a bolt's clamping force were experimentally and numerically studied in two plate structures connected using a bolt; where the clamping force ranged from 60 % to 100 %

Journal of the Korean Society for Aeronautical & Space Sciences, 2011

In this study, the aeroelastic analysis of rotorcraft in forward flight has been performed using dynamic inflow model to handle unsteady aerodynamics. The quasi-steady airload model based on the blade element method has been coupled with dynamic inflow model developed by Peters and He. The nonlinear steady response to periodic motion is obtained by integrating the full finite element equation in time through a coupled trim procedure with a vehicle trim for stability analysis. The aerodynamic and structural characteristics of dynamic inflow model are validated against other numerical analysis results by comparing induced inflow and blade tip deflections(flap, lag). In order to validate aeroelastic stability of dynamic inflow model, lag damping are also compared with those of linear inflow model.

Journal of Korea Multimedia Society, 2013

The Transactions of The Korean Institute of Electrical Engineers, 2014

The purpose of this study was to extract accurate parameters of facial movement features using 3-D motion capture system in speech recognition technology through lip-reading. Instead of using the features obtained through traditional camera image, the 3-D motion system was used to obtain quantitative data for actual facial movements, and to analyze 11 variables that exhibit particular patterns such as nose, lip, jaw and cheek movements in monosyllable vocalizations. Fourteen subjects, all in 20s of age, were asked to vocalize 11 types of Korean vowel monosyllables for three times with 36 reflective markers on their faces. The obtained facial movement data were then calculated into 11 parameters and presented as patterns for each monosyllable vocalization. The parameter patterns were performed through learning and recognizing process for each monosyllable with speech recognition algorithms with Hidden Markov Model (HMM) and Viterbi algorithm. The accuracy rate of 11 monosyllables recognition was 97.2%, which suggests the possibility of voice recognition of Korean language through quantitative facial movement analysis.

Journal of Korea Spatial Information Society, 2014

The Triangle Mesh Warping method is suggested and applied in coordinate transformation to world geodetic system in this study. The common points of Uiwang city are used to compare the transformation accuracy of the suggested methods with existing national coordinate transformation methods. As a result, the Triangle Mesh Warping method was satisfied with accuracy criteria for positioning on a map larger than scale 1/1,000 with smaller number of common points and without distortion modeling. Additionally, in case of Guri and Pyeongtaek city that established the World Geodetic System, the suggested method generates the result of transformation accuracy better than 5cm. Based on the test, it was found that the suggested method improves the problem of securing many common points and reduces the problem of mis-match between the transformed data of adjacent areas. Accordingly, for transformation of large-scale topographic map, cadastral map, GIS DB and serial cadastral map to the World Geodetic System, it is judged that the Triangle Mesh Warping would be a good method for economical efficiency and accuracy using by minimum common point.

Clean Technology, 2014

In this study, we studied optical properties on the layer-by-layer (LbL) assemblies consisting of Au nanorods and organic dyes. For this purpose, poly (allylamine hydrochloride), PAH and poly (styrene sulfonate), PSS were selected as ionic polymers and rhodamine B isothiocyanate (RB) was utilized as an organic dye based on its spectral overlap with plasmon band of Au nanorods. In the view point of assembling methods, RB was covalently attached to PAH, then, LbL structure of Au [PSS/PAH]2/PSS/PAH-RB was prepared by sequential coating of PAH, PSS, PAH-RB on Au nanorods. Since the prepared LbL assembly exhibits both plasmonic and fluorescent properties, we studied the mutual nanorod-dye properties by dissolving Au nanorods.