• 제어로봇시스템학회:학술대회논문집
• /
• 1989.10a
• /
• pp.621-626
• /
• 1989

An efficient algorithm for planning near-optimum trajectory of manipulators is proposed. The algorithm is divided into two stages. The first one is the optimization of time trajectory with given spatial path. And the second one is the optimization of the spatial path itself. To consider the second problem, the manipulator dynamics is represented using the path parameter "s", then a differential equation corresponding to the dynamics is solved as two point boundary value problem. In this procedure, the gradient method is used to calculate improved input torques.t torques.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.9
• /
• pp.62-69
• /
• 1996

Interpolator is a very important element in NC machines in that it controls tool path and speed. In this paper, studied were extensive interpolation characteristics of reference pulse method among various interpolation and pulse generation methods. Specifically, processing speed and path error of DDA, SPD and SFG methods were compared and analyzed against line, circle and elipse. As a result, in the point of processing speed, SPD method was found to be the best for line interpolation, SFG method for circle and ellipse, and DDA method was found to be the slowest for all paths. In the point of path error, DDA method was found to have the biggest error for all kinds of paths.

• Current Optics and Photonics
• /
• v.3 no.1
• /
• pp.16-21
• /
• 2019

We present a broad-bandwidth comb-spacing-swept source (CSWS) based on a differential polarization delay line (DPDL) for interferometric three-dimensional (3D) imaging. The comb spacing of the CSWS is repeatedly swept by the tunable DPDL in the multiwavelength source to provide depth-scanning optical coherence tomography (OCT). As the polarization differential delay of the DPDL is tuned from 5 to 15 ps, the comb spacing along the wavelength continuously varies from 1.6 to 0.53 nm, respectively. The wavelength range of various semiconductor optical amplifiers and the cavity feedback ratio of the tunable fiber coupler are experimentally selected to obtain optimal conditions for a broader 3-dB bandwidth of the multiwavelength spectrum and thus provide a higher axial resolution of $35{\mu}m$ in interferometric OCT imaging. The proposed CSWS-OCT has a simple imaging interferometer configuration without reference-path scanning and a simple imaging process without the complex Fourier transform. 3D surface images of a via-hole structure on a printed circuit board and the top surface of a coin were acquired.

• Proceedings of the KIEE Conference
• /
• 1999.11c
• /
• pp.500-502
• /
• 1999

This thesis deals with study and implementation of a cross-coupling controller which can enhance the path-tracking performance of optically guided AGV(Automated Guided Vehicle). The AGV in this thesis is differential drive type and has front-side and rear-side optical sensors, which can identify the guiding path. When AGV from the path due to the inevitable error and the deviation must be corrected. It has been shown that compensation only the first term can lead to undesirable oscillatory results and even instability but compensating only the second term leads to a steady state offset error. Cross-coupling control directly minimizes the error by coordinating the motion of the two drive wheels. The cross-coupling controller is analyzed to evaluate its performance. The cross-coupling controller enhances transient performance of the controller is demonstrated by simulation and is compared with that of individual loop controller.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.9 no.6 s.46
• /
• pp.53-58
• /
• 2005

Semi-analytical methodology to examine the dynamic responses of a bridge is developed via the joint probability density function. The evolution of joint probability density function is evaluated by the semi-analytical procedure developed. The joint probability function of the bridge responses can be obtained by solving the path-integral solution of the Fokker-Planet equation corresponding to the stochastic differential equations of the system. The response characteristics are observed from the joint probability density function and the boundary of the envelope of the probability density function can provide the maxima ol the bridge responses.

• Journal of The Korean Association For Science Education
• /
• v.33 no.5
• /
• pp.981-994
• /
• 2013

This study aims to examine two hypothetical models for the variables of students' environmental perspective. First hypothetical model is the mediating role of recognition and familiarity between aesthetic and negativistic perspectives. Second hypothetical model is the separate path from humanistic to dominionistic perspectives. One hundred four tenth grade students participated in this study. We used Pearson correlation, partial correlation, and path analysis to examine the fitness of hypothetical models. The findings showed that the mediating role of recognition and familiarity between aesthetic and negativistic perspectives were statistically accepted. To prevent students' bias for fancy or gross animals, the learning (for instance, recognition and familiarity) may play role in reducing the bias. Second, there were two differential paths from humanistic to dominionistic perspectives (ecologistic-naturalistic path and scientistic-utilitarian path). While ecologistic-naturalistic path does not reach dominionistic perspective, scientistic-utilitarian path does reach dominionistic perspective. To prevent students' dominionistic perspective for nature, they need to understand ecologistic-naturalistic minds for the nature.

• ETRI Journal
• /
• v.40 no.3
• /
• pp.347-354
• /
• 2018

Using various offset times to separate differential services is the most common form of service differentiation in optical burst switching networks. In this approach, a larger offset time is given to a higher priority burst, but it causes this burst to have a longer delay. One solution to this problem is to adjust the burst assembly time so that the buffering delay of the higher priority burst is always shorter than that of the lower priority burst. However, this adjustment causes another problem, called delay unfairness, for bursts with differential priorities that share the same path to their destination. This article proposes a new solution for delay fairness using the burst assembly.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.113.3-113
• /
• 2001

In this paper, we have designed the VHDL module of DS/SS QPSK wireless modem processor for digital data communication. The spread spectrum method is used for modern processor, because this method guarantees good frequency efficiency and higher security. Also, it guarantees good performance in digital communication system under multi-path interferences. The differential encoder and decoder are used for simple circuit composition in the signal detection. For the synchronization of receiver, matched filter and power detector are used. And the IF modulation/demodulation of QPSK method is used in the digital level. The transmitter of VHDL modem processor consists of differential encoder, PN code generator, and QPSK ...

• Journal of the Korea Institute of Military Science and Technology
• /
• v.14 no.2
• /
• pp.161-166
• /
• 2011

The passive open-path Fourier-Transform-Infrared system was implemented for the toxic gas monitoring. Noise Equivalent Differential Temperature(NEDT) was investigated as a system performance evaluation figure and analyzed numerically with the designed parameters. Calculated NEDT was compared with the experimental value in the wavelength region of $700{\sim}1400cm^{-1}^$. The minimum detectable gas concentration was estimated from the obtained NEDT at the absorption wavelength of $SF_6$.

• Journal of applied mathematics & informatics
• /
• v.23 no.1_2
• /
• pp.243-256
• /
• 2007

This paper deals with determining the sufficient conditions of minimum for the class of problems in which the necessary conditions of optimum are satisfied in the strengthened form Legendre-Clebsch. To this paper, we shall use the sweep method which analysis the conditions of existence of the conjugated points on the optimal trajectory. The study we have done evaluates the command variation on the neighboring optimal trajectory. The sufficient conditions of minimum are obtained by imposing the positivity of the second variation. The results that this method offers are applied to the problem o the orbital rendez-vous for the linear case of the equations of movement.