• Journal of the Korea Convergence Society
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• v.7 no.5
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• pp.155-160
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• 2016

The education applications for English learning have been developing consistently by utilizing the smart-phone owing to the development of internet and ICT. Smart technology based study platform, the mobile learning which enables for the students to study beyond the time and space is expected to bring forth new paradigm of education in tune with the environment change and trends. But it is found that the current applications are mostly the contents patterned for English study institution information with single channel or made for thinking study concept with only the simple language learning once they were checked. Therefore, the understanding on the English study process shall be changed and the study on the platform service is required by accessing in the viewpoint of thinking exercise learning. This study is purposed to explore the scope and strategy of mobile learning UX platform development and suggest the service model via prototype for English study.

• Journal of the Korea Convergence Society
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• v.11 no.2
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• pp.17-22
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• 2020

In this paper, we measured the user's EEG signal and classified the EEG signal using the Support Vector Machine algorithm and measured the accuracy of the signal. An experiment was conducted to measure the user's EEG signals by separating men and women, and a single channel EEG device was used for EEG signal measurements. The results of measuring users' EEG signals using EEG devices were analyzed using R. In addition, data in the study was predicted using a 80:20 ratio between training data and test data by applying a combination of specific vectors with the highest classifying performance of the SVM, and thus the predicted accuracy of 93.2% of the recognition rate. This paper suggested that the user's EEG signal could be recognized at about 93.2 percent, and that it can be performed only by simple linear classification of the SVM algorithm, which can be used variously for biometrics using EEG signals.

• Journal of Korea Game Society
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• v.15 no.2
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• pp.105-114
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• 2015

We propose a real time user interface that utilizes emotion recognition by physiological signals. To improve the problem that was low accuracy of emotion recognition through the traditional EEG(ElectroEncephaloGram), We developed a physiological signals-based emotion recognition system mixing relative power spectrum values of theta/alpha/beta/gamma EEG waves and autonomic nerve signal ratio of ECG (ElectroCardioGram). We propose both a data map and weight value modification algorithm to recognize six emotions of happy, fear, sad, joy, anger, and hatred. The datamap that stores the user-specific probability value is created and the algorithm updates the weighting to improve the accuracy of emotion recognition corresponding to each EEG channel. Also, as we compared the results of the EEG/ECG bio-singal complex data and single data consisting of EEG, the accuracy went up 23.77%. The proposed interface system with high accuracy will be utillized as a useful interface for controlling the game spaces and smart spaces.

• Korean Chemical Engineering Research
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• v.54 no.6
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• pp.847-853
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• 2016

Here has been examined a 3-dimensional computational fluid dynamics (CFD) modeling in order to investigate the performance analysis of proton exchange membrane (PEM) fuel cells with serpentine flow fields. The present CFD model considers the isothermal transport phenomena in a fuel cell involving mass, momentum transport, electrode kinetics, and potential fields. Co-current flow patterns for a PEMFC are considered for various geometries in the single straight cell. Current density distribution from the calculated distribution of oxygen and hydrogen mass fractions has been determined, where the activation overpotential has been also calculated within anode and cathode. CFD results showed that profiles differ from those simulations subjected to each the calculated activation overpotential. It is interesting that the present serpentine flow field shows the specific distribution of current density with respect to the aspect ratio of depth to width and the ratio of reaction area for various serpentine geometries. Simulation results were considered reasonable with the other CFD results reported in literature and global comparisons of the PEMFC model.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.10
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• pp.35-43
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• 2004

An arbitration method is proposed to resolve a collision and arbitrate beacon transmissions in an indoor Positioning system consisting of multiple beacons and listeners. Although two or more beacons may compete to transmit signals simultaneously, a single winner in the competition is determined autonomously through the arbitration process while they are transmitting. So, it can continue to send its data, but the others give up their transmissions during the arbitration process. As a consequence, update rate for location information and channel utilization can be improved by avoiding that all beacons fail due to a collision. Once a beacon succeeds in transmitting its signal, a low-level priority is assigned to it. And a high-level priority is allocated to a beacon which gave up its transmission during arbitration process. This will guarantee every beacon has fair transmission opportunity with the arbitration method. As no centralized control is required among beacons, a Positioning system can still be easily deployed and expanded with this arbitration method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.442-446
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• 2000

The metal-oxide-semiconductor field-effect transistor(MOSFET) has undergone many changes in the last decade in response to the constant demand for increased speed, decreased power, and increased parking density. Therefore, it was interested in scaling theory, and full-band Monte Carlo device simulator has been used to study the effects of device scaling on hot carriers in different MOSFET structures. MOSFET structures investigated in this study include a conventional MOSFET with a single source/drain, implant a lightly-doped drain(LDD) MOSFET, and a MOSFET built on an epitaxial layer(EPI) of a heavily-doped ground plane, and those are analyzed using TCAD(Technology Computer Aided Design) for scaling and simulation. The scaling has used a constant-voltage scaling method, and we have presented MOSFET´s characteristics such as I-V characteristic, impact ionization, electric field and recognized usefulness of TCAD, providing a physical basis for understanding how they relate to scaling.

• Journal of Communications and Networks
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• v.12 no.2
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• pp.103-113
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• 2010

In this paper, a tradeoff between the total energy consumption-per-bit and the end-to-end rate under spatial reuse in wireless multi-hop network is developed and analyzed. The end-to-end rate of the network is the number of information bits transmitted (end-to-end) per channel use by any node in the network that is forwarding the data. In order to increase the bandwidth efficiency, spatial reuse is considered whereby simultaneous relay transmissions are allowed provided there is a minimum separation between such transmitters. The total energy consumption-per-bit includes the energy transmitted and the energy consumed by the receiver to process (demodulate and decoder) the received signal. The total energy consumption-per-bit is normalized by the distance between a source-destination pair in order to be consistent with a direct (single-hop) communication network. Lower bounds on this energy-bandwidth tradeoff are analyzed using convex optimization methods. For a given location of relays, it is shown that the total energy consumption-per-bit is minimized by optimally selecting the end-to-end rate. It is also demonstrated that spatial reuse can improve the bandwidth efficiency for a given total energy consumption-per-bit. However, at the rate that minimizes the total energy consumption-per-bit, spatial reuse does not provide lower energy consumption-per-bit compared to the case without spatial reuse. This is because spatial reuse requires more receiver energy consumption at a given end-to-end rate. Such degraded energy efficiency can be compensated by varying the minimum separation of hops between simultaneous transmitters. In the case of equi-spaced relays, analytical results for the energy-bandwidth tradeoff are provided and it is shown that the minimum energy consumption-per-bit decreases linearly with the end-to-end distance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12B
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• pp.735-742
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• 2007

We propose an effective packet marking algorithm for video streaming in DiffServ network. Because legacy packet markers such as srTCM(single rate three color marker) cannot distinguish the importance of packet, these markers can cause quality degradation of streaming during the network congestion period. Recently proposed TMS (Two Marker System) [4] shows effectiveness in such scenario that video streaming service is struggling with other types of service traffic. However, if many video streaming services co-exist in DiffServ network and result in competition among themselves, then both legacy packet markers and even TMS cannot prevent drastic streaming quality degradation. To cope with this, we suggest A-TCPM (Adaptive time sliding window Three Color Marker) algorithm. In this algorithm, an A-TCPM module decides the color of a racket based upon the probability which is lead by current channel status and frame importance ratio. Simulation results show that proposed A-TCPM algorithm can enhance streaming service quality especially when overbooked video streaming sessions struggle with themselves.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.7
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• pp.440-448
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• 2014

A $4{\times}10$ Gb/s Transimpedance Amplifier (TIA) array is implemented in $0.13{\mu}m$ CMOS process technology, which will be used in the receiver of TWDM-PON system. A technology for bandwidth enhancement of a given $4{\times}10$ Gb/s TIA presented under inductor peaking technology and a single 1.2V power supply based low voltage design technology. It achieves 3 dB bandwidth of 7 GHz in the presence of a 0.5 pF photodiode capacitance. The trans-resistance gain is $50dB{\Omega}$, while 48 mW/ 1channel from a 1.2 V supply. The input sensitivity of the TIA is -27 dBm. The chip size is $1.9mm{\times}2.2mm$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.8
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• pp.875-881
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• 2004

Fundamental results obtained from an atomic force microscope (AFM) chemically-induced direct nano-lithography process are presented, which is regarded as a simple method for fabrication nm-scale devices such as superconducting flux flow transistors (SFFTs) and single electron tunneling transistors (SETs). Si cantilevers with Pt coating and with 30 nm thick TiO coating were used as conducting AFM tips in this study. We observed the surfaces of superconducting strip lines modified by AFM anodization' process. First, superconducting strip lines with scan size 2 ${\mu}{\textrm}{m}$${\times}$2 ${\mu}{\textrm}{m}$ have been anodized by AFM technology. The surface roughness was increased with the number of AFM scanning, The roughness variation was higher in case of the AFM tip with a positive voltage than with a negative voltage in respect of the strip surface. Second, we have patterned nm-scale oxide lines on ${YBa}-2{Cu}_3{O}_{7-x}$ superconducting microstrip surfaces by AFM conductive cantilever with a negative bias voltage. The ${YBa}-2{Cu}_3{O}_{7-x}$ oxide lines could be patterned by anodization technique. This research showed that the critical characteristics of superconducting thin films were be controlled by AFM anodization process technique. The AFM technique was expected to be used as a promising anodization technique for fabrication of an SFFT with nano-channel.