• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.519-524
• /
• 2003

In this report, a longitudinal adaptive flight control law is presented for the automatic landing system of a Japanese automatic landing flight experiment vehicle (ALFLEX). The longitudinal adaptive flight control law is designed to track an output of the vehicle to a guidance signal from the guidance portion of the automatic landing system. The proposed adaptive control law in the attitude control portion adjusts the controller gains continuously online as flight conditions change, in spite of the existence of unmodeled dynamics. The number of the controller gains to be adjusted is decreased to 1/2 from the previous studies. Computer simulation involving six-degree-of-freedom (DOF) nonlinear flight dynamics is performed to examine the effectiveness of the proposed adaptive control law. In order to verify the influence of the dispersion of the initial conditions, the Monte Carlo simulation is also applied. The initial conditions are more widely dispersed than the previous studies. As a result, except under the unsuitable initial conditions, the ALFLEX successfully landed on the runway.

• Journal of Electrical Engineering and Technology
• /
• v.11 no.6
• /
• pp.1614-1627
• /
• 2016

The purpose of this paper is to investigate the united Electromagnetic characteristics for the effective monitoring on the static air-gap eccentricity (SAGE) of turbo-generator. Different from other studies, this paper not only studies on the unbalanced magnetic pull (UMP) and the vibration characteristics of the stator and the rotor, but also investigates the harmonic features of the magnetic flux density and the circulating current inside the parallel branches (CCPB). The theoretical calculation, together with the finite-element-method (FEM) simulation and the experiment verification, is taken for a SDF-9 type non-salient generator. It is shown that, when SAGE occurs, apparent double-frequency UMP and vibrations will be produced both on the stator and the rotor, while the CCPB will have an obvious increment at the $1^{st}$ harmonic component. In addition, the amplitude of the magnetic flux density will be of cosine distribution in the circumferential position of the air-gap, while in normal condition it is a constant. Moreover, the pass-band amplitude, together with the $1^{st}$ harmonic of the magnetic flux density, will be enlarged as well. These united electromagnetic characteristics can be used as the diagnosis and monitoring criterion for SAGE.

• Journal of The Korean Association of Information Education
• /
• v.20 no.5
• /
• pp.433-442
• /
• 2016

The purpose of this paper is to prove the effect of flipped learning on learning motivation in software education. For this study, the experiment was consisted of experimental group and control group for university of education. They learned software education using Scratch programming for 10 weeks. The experimental group was applied to the flipped learning with online software courses. As a result, post motivation in the experimental group was significantly increased compared to the pre learning motivation. Post- learning motivation is also the experimental group were higher learning motivation significantly compared to the control group. It is hoped this flipped learning as an effective learning strategies base expansion in primary and secondary education as well as high education teaching software in the future.

• Phonetics and Speech Sciences
• /
• v.1 no.4
• /
• pp.3-9
• /
• 2009

Acoustically English vowels are defined primarily by formant values. The measurements of the values have been usually made at a few time points of the vowel segment despite the fact that the majority of English vowel formants vary dynamically throughout the segment. This study attempts to collect acoustic data of the nine English vowels published by Hillenbrand et al. (1995) online and to examine the acoustic features of the English vowels for phoneticians and English teachers. The author used Praat to obtain the data systematically at six equidistant timepoints over the vowel segment. Obvious errors were corrected based on the spectrographic display of each vowel. Results show that the first two formant trajectories are important to separate the nine vowels within the front- or back-vowel groups. The third formant trajectories appear comparable except those of the high vowels. Second, the back vowels leave longer traces on the vowel space toward the locus of the following consonant /d/. Third, each vowel has inherent duration, pitch, and intensity patterns. The results match the findings of Yang (2009). From the results, the author concludes that dynamic spectral changes are important in specifying acoustic characteristics of English vowels. Further studies on the application of the vowel trajectories to English pronunciation lessons or on perceptual experiment of synthesized vowels are desirable.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.20 no.4
• /
• pp.57-69
• /
• 2012

The purpose of this study was to identify the effect of experience emotion (i.e., happy, proud, sad, fear) on the risk perception. This study also examined interaction effects of emotion regulation (i.e., reappraisal strategy, problem focused strategy) between experience emotion and risk perception. The study collected data from 168 flight crew members in Korean commercial airlines, using an online research in which an experiment of emotion manipulation and a survey were included. The results of the study found the positive effect of happiness emotion on the risk perception regarding cases 1(these cases have high possibility of negative result and low circumstance control) and the positive effect of sadness emotion on the risk perception regarding cases 2(these cases have low possibility of negative result and high circumstance control). This study also found the interaction effect of reappraisal emotion regulation strategy between the relationship of happiness and risk perception regarding cases 2. From these results, the study provided that theoretical and practical implication that happiness and sadness emotion contribute risk perception and reappraisal strategy has a moderating role in the relationship between happy emotion and risk perception. Finally, based on these results, the limitations of this study and future research were discussed.

• Smart Structures and Systems
• /
• v.11 no.1
• /
• pp.19-34
• /
• 2013

The objective of this paper is to develop on-line system parameter estimation and damage detection technique from the response measurements through using the Recursive Covariance-Driven Stochastic Subspace identification (RSSI-COV) approach. To reduce the effect of noise on the results of identification, discussion on the pre-processing of data using recursive singular spectrum analysis (rSSA) is presented to remove the noise contaminant measurements so as to enhance the stability of data analysis. Through the application of rSSA-SSI-COV to the vibration measurement of bridge during scouring experiment, the ability of the proposed algorithm was proved to be robust to the noise perturbations and offers a very good online tracking capability. The accuracy and robustness offered by rSSA-SSI-COV provides a key to obtain the evidence of imminent bridge settlement and a very stable modal frequency tracking which makes it possible for early warning. The peak values of the identified $1^{st}$ mode shape slope ratio has shown to be a good indicator for damage location, meanwhile, the drastic movements of the peak of $2^{nd}$ mode slope ratio could be used as another feature to indicate imminent pier settlement.

• Journal of Korean Library and Information Science Society
• /
• v.43 no.1
• /
• pp.143-171
• /
• 2012

The primary questions addressed by this research are the followings: Have the OPAC interfaces of children's libraries been designed user-friendly; What difficulties have OPAC searchers experienced in using OPACs; How do they perceive the system after searching it; Through the answers of those questions the problems of OPACs for children as searching tools have been grasped and recommendations have been suggested in order to improve the OPAC interfaces. An experiment was conducted and 28 children of grades 4 to 6 performed 5 searching tasks. The searching behavior of OPAC searchers has been analyzed thoroughly. The data of their perceptions about the system was collected through a questionnaire after completing the tasks.

• Journal of the Korean Society for information Management
• /
• v.25 no.1
• /
• pp.75-98
• /
• 2008

With explosive growth in the area of the Internet and IT services, various types of e-documents are generated and circulated. An e-Document is a sort of electronic records which a organization performs works and goals. In this study, we propose a security algorithm for secure use and distribution of e-documents. Especially, the proposed method can be applied to generate digital signature which can guarantee authenticity, integrity, confidentiality of an e-document and authenticate authorized users. Also, we can get higher security level as using a smart card that provides highly storing capacity and security. We carried out an experiment to verify efficiency and security of the proposed method.

• Journal of Korea Multimedia Society
• /
• v.15 no.11
• /
• pp.1391-1398
• /
• 2012

Time synchronization is crucial in wireless sensor networks such as Wireless USB and WBAN for diverse purposes from the MAC to the application layer. This paper proposes online clock skew estimators to achieve energy-efficient time synchronization for wireless sensor networks. By using recursive least squares estimators, we not only reduce the amount of data which should be stored locally in a table at each sensor node, but also allow offset and skew compensations to be processed simultaneously. Our skew estimators can be easily integrated with traditional offset compensation schemes. The results of simulation and experiment show that the accuracy of time synchronization can be greatly improved through our skew compensation algorithm.

• Annual Conference on Human and Language Technology
• /
• 2018.10a
• /
• pp.652-657
• /
• 2018

With the rapid development of e-commerce, many customers can now express their opinion on various kinds of product at discussion groups, merchant sites, social networks, etc. Discerning a consensus opinion about a product sold online is difficult due to more and more reviews become available on the internet. Opinion Mining, also known as Sentiment analysis, is the task of automatically detecting and understanding the sentimental expressions about a product from customer textual reviews. Recently, researchers have proposed various approaches for evaluation in sentiment mining by applying several techniques for document, sentence and aspect level. Aspect-based sentiment analysis is getting widely interesting of researchers; however, more complex algorithms are needed to address this issue precisely with larger corpora. This paper introduces an approach of knowledge representation for the task of analyzing product aspect rating. We focus on how to form the nature of sentiment representation from textual opinion by utilizing the representation learning methods which include word embedding and compositional vector models. Our experiment is performed on a dataset of reviews from electronic domain and the obtained result show that the proposed system achieved outstanding methods in previous studies.