• Polymer(Korea)
• /
• v.26 no.2
• /
• pp.253-259
• /
• 2002

The objective of this study is to obtain thermally stable and low optical loss polymers for optical waveguiding materials. The crosslinkable poly (maleimide-co-methacrylate)s were synthesized using a pentafluorophenylmaleimide (an optical loss reducer), two methacrylate derivatives (refractive index controllers), and a glycidylmethacrylate (a crosslinker). These copolymers exhibited good thermal stability and could be thermally crosslinked by heat treatment. The refractive indexes of the copolymers could be precisely controlled by the variation of comonomer feed ratio, which was in the range of 1.45 ~ 1.49. These copolymers had very low birefringence of $6{ imes}10^{-4}$ ~ $1{ imes}10^{-4}$. These copolymers were crosslinked by contact printing and then developed by wet etching to obtain high quality waveguide pattern.

• Proceedings of the Korea Institute of Convergence Signal Processing
• /
• 2001.06a
• /
• pp.285-288
• /
• 2001

In this paper, we proposed new method of speech feature extraction using ICA(Independent Component Analysis) which minimized the dependency and correlation among speech signals on purpose to separate each component in the speech signal. ICA removes the repeating of data after finding the axis direction which has the greatest variance in input dimension. We verified improvement of speech recognition ability with training and recognition experiments when ICA compared with conventional mel-cepstrum features using HMM. Also, we can see that ICA dealt with the situation of recognition ability decline that is caused by environmental noise.

• Proceedings of the KIEE Conference
• /
• 1997.07c
• /
• pp.1124-1126
• /
• 1997

The Unified Power Flow Controller(UPFC) with a series inverter and a shunt inverter ia able to control all three line Parameters(voltage, impedance and phase angle) and so UPFC technology has the potential to enhance the implementation and broad application of the FACTS concept with improved Performance. In this Paper, the UPFC is applied in order to improve the power flow oscillation damping. The modal performance measure is minimized in order to determine the optimal parameters of UPFC controller for damping Power flow oscillations. The dynamics of the injected voltage of UPFC is represented as a first order delay element. The UPFC controller used here is of the PIO type and the input signal to the controller is the active power flow through the UPFC. The effect of UPFC application to the Power system are analyzed from the stand point of power system oscillation damping.

• Proceedings of the KSR Conference
• /
• 2009.05a
• /
• pp.1489-1497
• /
• 2009

The rectifier for Electric railway is one of the most important facilities in DC urban railway which converts power from KEPCO(AC 22.9kV) to the electric mil car(DC 1.5kV), therefore it should be managed as the best condition for the drive. There are several things to cause performance degradation and deterioration of parts such as pollutants occurred by it established under the ground such as dust or foreign substances, rapid changes of driving current, and pyrogen which put the rectifier for Electric railway in malfunction. On the flow of time, the rectifier for Electric railway is causing a malfunction or failure which drive electric rail car in operations as well as loss of life. In this research we try to find the way of removing the various components of mal-functions in the performance of the rectifier for Electric railway by Over-Haul and reform itself, which gives us to get the chance investment of the reduction, the reliability of power supply to the electric rail car.

• Proceedings of the KSR Conference
• /
• 2005.11a
• /
• pp.699-704
• /
• 2005

In the station of the railway and the subway various illumination equipment and a general power equipment for a passenger convenience, the signal equipment and the communication equipment which is necessary to the train operation provided. At the all of like this equipment from the electric room which is established in each station by changing from high voltage to low voltage and it supplies from the illumination transformer, the power transformer and the signal transformer. If it supplies to the equipment from the high voltage to the low voltage, it must be established to contact protection device in between the high voltage coil and the low voltage coil. Also it must do the grounding faulting device at the low voltage lines, the earthing devices at apparatus for the protection of an electric shock and an electric fire by the electric relation law. Compared the related regulations between the facilities which require protective functions such as grounding fault or earthing in public utilities like subway stations, and the facilities which do not require line earthing or protective functions such as electricity supplied for signalling the train. Also, will describe a countermeasure for the accident from a grounding fault.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• v.9 no.2
• /
• pp.639-642
• /
• 2005

In this paper, we assessed the subjective and objective quality of the images on low bit-rate which used the H.264 intra coding and JPEG2000. The result of our experiments shown the subjective and objective quality assessment of the intra coded image of H.264 high profile is better than JPEG2000. But, the blocking artifact is obvious because of the big difference of DCT and wavelet transform and quantization. it will be necessary to propose a new transform algorithm for the optimal quality.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.12B
• /
• pp.2447-2454
• /
• 1999

This paper proposes a N-APPEM(Nonlinear A Posteriori Probability Estimation Method) with a frame normalization method to conventional classification network to increase speech recognition ability. It also tests the recognition ability of the classification and prediction neural networks for the Korean isolated digits. From the experimental results, the prediction network with MLP(Multi-Layer Perceptron) achieves the highest recognition ability of 98.0%. The prediction requires very complicated networks increased linearly with the number of incoming speech categories. However, the classification network with the N-APPEM and the normalization improves the recognition ability up to 85.5% with a sin81e network, which is almost 12.0% improvement.

• Proceedings of the Korean Society of Dyers and Finishers Conference
• /
• 2011.11a
• /
• pp.23-23
• /
• 2011

신라는 유잠국을 거쳐 새로운 비단이라는 신라(新羅)로 국호를 변경한다. 신라 뽕나무와 비단의 행방을 �O는다면 실크로드의 출발점이 한반도의 신라의 땅이라는 추정에 의거하여 1995년부터 조사를 하였다. 특히 삼국사기의 내용을 기초로 하여 한반도의 지명을 방문하여 조사하는 과정에서 삼국사기의 내용이 전혀 한반도에는 정확하게 일치하지 않는다는 사실을 확인하였다. 1. 신라는 한반도에 없었다. 최근 한학자이신 이중재님이 발표한 논문과 책자를 기초로 조사 검정을 하는 중에 고구려, 신라 백제가 한반도에 없었다는 사실을 확인 하였다. 2. 중국고금지명대사전(1931)을 중국 청도에서 섬유공장장으로 근무하는 정윤화친구의 도움으로 구입하여 이중재의 책의 내용을 검정하였다. 그러므로 신라의 비단과 양잠을 한반도에서 확인하는 것은 잘못된 사실이라는 것을 확인하였다. 3. 삼국사기의 내용을 중국고금지명사전을 이용하여 확인한 결과 그동안 의문으로 되어 있는 임라설, 가야설, 고구려 신라 백제의 강역, 문익점 선생의 최초의 목화에 대한 사실 등 모든 사실을 잘못된 내용이라는 것을 확인 검정하였고, 현재의 한반도의 역사는 식민주의 역사학자들이 한반도의 역사를 왜곡한 사실을 확인하였다. 4. 한반도에서는 고려시대 이전에는 나라 형태의 국가는 없었고, 조선시대부터 국가의 형태가 성립되었다.

• Journal of Korea Game Society
• /
• v.21 no.4
• /
• pp.85-94
• /
• 2021

The purpose of this study is to analyze the educational effect of non-face-to-face classes in elementary school social studies using Minecraft. the fourth grade of elementary school is divided into experimental and control groups, and social studies using Minecraft are conducted for one semester. As a result of the study, the experimental group students who experienced elementary social studies classes using Minecraft showed a significant increase in achievement, learning attitude, and sense of place compared to the control group, focusing on questions, explanations, and opinions in the Minecraft virtual space It was confirmed that they were cooperating with each other.

• Journal of Digital Contents Society
• /
• v.19 no.6
• /
• pp.1115-1121
• /
• 2018

In this paper, we have studied a data analysis method by deep learning to predict learning achievements based on accumulated data in cyber university learning management system. By predicting learner's academic achievement, it can be used as a tool to enhance learner's learning and improve the quality of education. In order to improve the accuracy of prediction of learning achievements, the autoencoder based attendance prediction method is developed to improve the prediction performance and deep learning algorithm with ongoing evaluation metrics and predicted attendance are used to predict the final score. In order to verify the prediction results of the proposed method, the final grade was predicted by using the evaluation factor attendance data of the learning process. The experimental result showed that we can predict the learning achievements in the middle of semester.