• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.19 no.12
• /
• pp.2386-2396
• /
• 1994

In this paper, an optimal algorithm for the design of 1-D FIR filters with finite precision coefficients is proposed. The algorithm is based on the observation that the frequency constraints of a sub-problems(SP) in the branch and bound algorithm, which repeatedly use LP(linear programming), are closely related with those of neighboring SPs. By using the relationship between the SPs, the proposed algorithm reduces the number of constraints required for solving each SP with Lp, whereas the conventional algorithm employs all the constraints, which are required for solving the initial problem. Thus, the overall computational load for the design of FIR filters with finite precision coefficients is significantly alleviated, compared to the conventional branch and bound algorithm. Also, a new branching scheme for the design of FIR filters with sum-of-power-of-two(SOPOT) coefficients is proposed. It is shown that the computational load for the design fo SOPT coefficient filters can be further reduced with the new branching scheme.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.40 no.3
• /
• pp.207-215
• /
• 2022

This research has been focused on accessing precision and accuracy of UAV (Unmanned Aerial Vehicle)-derived 3-D surveying coordinates. To this end, a highly precise and accurate testing control network had been established by GNSS (Global Navigation Satellite Systems) campaign and its network adjustment. The coordinates of the ground control points and the check points were estimated within 1cm accuracy for 95% of the confidence level. FC330 camera mounted on DJI Phantom 4 repeatedly took aerial photos of an experimental area seven times, and then processed them by two widely used software packages. To evaluate the precision and accuracy of the aerial surveys, 3-D coordinates of the ten check points which automatically extracted by software were compared with GNSS solutions. For the 95% confidence level, the standard deviation of two software's result is within 1cm, 2cm, and 4cm for the north-south, east-west, and height direction, and RMSE (Root Mean Square Error) is within 9cm and 8cm for the horizontal, vertical component, respectively. The interest is that the standard deviation is much smaller than RMSE. The F-ratio test was performed to confirm the statistical difference between the two software processing results. For the standard deviation and RMSE of most positional components, exception of RMSE of the height, the null hypothesis of the one-tailed tests was rejected. It indicates that the result of UAV photogrammetry can be different statistically based on the processing software.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.22 no.6
• /
• pp.607-615
• /
• 2009

Analysis of chloride penetration into concrete is performed considering the repeated wetting and drying conditions of tidal zone, by means of the developed finite element program which enables the diffusion-convection analysis to be conducted. Heat conduction and moisture diffusion are also included in the finite element analysis program in order that their effects to chloride penetration may be considered. For the efficiency of calculation, the analyses of temperature, relative humidity and free chloride concentration are conducted successively in that order, by treating the convection of chloride due to moisture diffusion as an source or sink term. By comparing the analysis result from finite element analysis, where main variable is a wetting and drying period, with the chloride profiles from ACI Life-365 method, it is shown that the Life-365 method gives an accurate result for the submerged zone but does not consider the differences of wetting and drying period. To obtain an accurate chloride profile in the tidal zone, it is confirmed that the diffusion-convection finite element analysis should be applied.

• Analytical Science and Technology
• /
• v.19 no.5
• /
• pp.433-440
• /
• 2006

A HPLC/UV method was developed and validated for the rapid and simultaneous determination of urinary metabolites of organic solvents, mandelic acid, hippuric acid, phenylglyoxylic acid, ortho-, meta- and para-methylhippuric acid, using a monolithic column. The mobile phase was composed of tetrabutylammonium bromide as ion-pairing reagent with a flow rate of 2.4 mL/min. The total run time was less than 2.5 min for all six analytes. Good linearities were obtained for all the metabolites with correlation coefficients above 0.9993. Intra-day precision, accuracy and inter-day precision was 0.01~7.32%, 83.9~116.3% and 0.01~7.16%, respectively. The method was validated and confirmed by quantification of the quality assurance samples of Industrial Safety and Health Research Institute, Korea Occupational Safety and Health Agency.

• Journal of the Korean Society for Precision Engineering
• /
• v.5 no.3
• /
• pp.71-80
• /
• 1988

This paper dealt with experimentally the effect of $N_2$ and $H_2$ gas mixtures ratio in the fatigue characteristics of SM45C on Ion-nitrided. The specimen were treated water cooling after Ion-nitriding at $500^{\circ}C$ and 5 torr. in 80% $N_2$and 50% $N_2$gas mixtures ratio in the atmosphere for 3 hrs. The hardness distribution and the depth of nitriding layer shows more increase in 80% $N_2$gas mixture ratio than 50% $N_2$. Ion-nitrided specim- en for 80% $N_2$gas mixture ratio show more increase infatigue strenght in the $>1.5{\times}10^5$ cycles region than 50% $N_2$. In the $<1.5{\times}10^5$cycles region, fatigue failure is due to cracking of the brittle nitrided case, and the propergation of the surface cracks into the core. But in the $>1.5{\times}10^5$cycles region, it is found that cracks propagate from the non-metallic inclusions in the subsurface.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.12 no.4
• /
• pp.334-340
• /
• 2002

This paper proposes a self-organizing fuzzy modeling which can create a new hyperplane-shaped cluster by applying multiple regression to input/output data with relatively large fuzzy entropy, add the new cluster to fuzzy rule base and adjust parameters of the fuzzy model in repetition. Tn the coarse tuning, weighted recursive least squared algorithm and fuzzy C-regression model clustering are used and in the fine tuning, gradient descent algorithm is used to adjust parameters of the fuzzy model precisely And learning rates are optimized by utilizing meiosis-genetic algorithm. To check the effectiveness and feasibility of the suggested algorithm, four representative examples for system identification are examined and the performance of the identified fuzzy model is demonstrated in comparison with that of the conventional fuzzy models.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.4
• /
• pp.120-131
• /
• 2004

In this paper, we propose the method of a motion planning generation in which the movement of the 3-link leg subsystem is constrained to a slider-link and a singular posture can be easily avoided. The proposed method is the jumping control moving in vertical direction which mimics a cat's behavior. That is, it is jumping toward wall and kicking it to get a higher-place. Considering the movement from the point of constraint mechanical system, the robotic system which realizes the motion changes its configuration according to the position and it has several phases such as; ⅰ) an one-leg phase, ⅱ) in an air-phase. In other words, the system is under nonholonomic constraint due to the reservation of its momentum. Especially, in an air-phase, we will use a control method using state transformation and linearization in order to control the landing posture. Also, an iterative learning control algorithm is applied in order to improve the robustness of the control. The simulation results for jumping control will illustrate the effectiveness of the proposed control method.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.9
• /
• pp.874-883
• /
• 2008

This study considers powered explicit guidance, one of the closed-loop guidance laws for satellite launch vehicles. The guidance algorithm employed here does not include the iterative procedure of the original algorithm. Also, the single-target algorithm to treat the general time-varying thrust profiles is described. The computer simulations for the 6-DOF launch vehicle model are performed to investigate the orbit injection accuracy of the guidance algorithm in the nominal/off-nominal flight conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.1051-1054
• /
• 2003

For micro-weighing, null balance method is widely used in the precision industrial fields, such as biomedicine, semiconductor, chemistry and so on. In order to obtain high resolution and large measurement range simultaneously, the mechanism should be analyzed and optimized. However, large measurement error can be generated according to the mass loading position and this error is called as a corner loading error. The corner loading error is caused by the parallelism error of a Roberval mechanism used to minimize it. The corner loading error is one of the most dominant error sources that should be removed. It is possible to design that the mechanism has no corner loading error theoretically, but the mechanism of the micro weighing device is very difficult to be realized as original design due to assembling and manufacturing error. For the required specification of the device, the precise manufacturing technique under a few $\mu\textrm{m}$ is required for the realization of the design. In this paper, the effects of the parallelism error are analyzed by using Lagrange method and verified by experiment. Also, the compensation mechanism is proposed and the corner loading error is reduced by restoring tile parallelism.

• Proceedings of the Korea Contents Association Conference
• /
• 2005.11a
• /
• pp.53-59
• /
• 2005

Reference Standard Data(RSD), which is a very high data of reliability, an authentic data of quality, can be used repetitively in industry, science and technology field. The more RSD is produced and used in various field, the more the level of detail of industry goods and reliability of material rise. It is also the nationally important information resource that improve the technology level of nation and international competitiveness. Before constructing RSD, this paper is used of the source data that recommend RSD's development direction and higher required RSD after we investigate what kind of RSD domestic users require in some field.