• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.5B
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• pp.318-325
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• 2008

HomePlug AV(HPAV) is the standard for distribution of Audio/video content as well as data within the home by using the power line. It uses a hybrid access mechanism that combines TDMA with CSMA/CA for MAC technology. The CSMA/CA protocol in HPAV has two main control blobs that can be used for access control: contention window(CW) size and deferral counter(DC). In this paper, we extensively investigate the impacts of CW and DC on performance through simulations, and propose an adaptive mechanism that adjusts the CW size to enhance the throughput in HPAV MAC. We find that the CW size is more influential on performance than the DC. Therefore, to make controlling the network easier, our proposal uses a default value of DC and adjusts the CW size. Our scheme simply increases or decreases the CW size if the network is too busy or too idle, respectively, We compare the performance of our proposal with those of the standard and other competitive schemes in terms of throughput and fairness. Our simulation and analysis results show that our adaptive CW mechanism performs very well under various scenarios.

• Journal of Broadcast Engineering
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• v.8 no.2
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• pp.198-203
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• 2003

We develop the method of estimating the endpoints of speech by jointly using the lip motion (visual speech) and speech being included in multimedia data and then propose a new speech recognition system (SRS) based on that method. The endpoints of noisy speech are estimated as follows : For each test word, two kinds of endpoints are detected from visual speech and clean speech, respectively Their difference is made and then added to the endpoints of visual speech to estimate those for noisy speech. This estimation method for endpoints (i.e. speech interval) is applied to form a new SRS. The SRS differs from the convention alone in that each word model in the recognizer is provided an interval of speech not Identical but estimated respectively for the corresponding word. Simulation results show that the proposed method enables the endpoints to be accurately estimated regardless of the amount of noise and consequently achieves 8 o/o improvement in recognition rate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.304-309
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• 2004

Recently, the needs for multimedia stream such as digital audio and video in the Internet has increased tremendously. Unlike TCP, the UDP protocol, which has been used to transmit streaming traffic thorough the Internet, does not apply any congestion control mechanism to regulate the data flow thorough the shared network And it leads to congestion collapse of the Internet and results in long-term transmission delay. To avoid any adverse effect on the current Internet functionality, a now protocol of modification or addition of some functionality to perform congestion control and to reduce huge transmission delay in transmitting of multimedia stream are in study. TCP-friendly congestion control mechanism is classified into two : one is window-based congestion control scheme using general window management functionalities, the other is rate-based congestion control scheme using TCP modeling equation. In this paper, we propose an algorithm for improving the transmitting rate on a hybrid TCP-friendly congestion control scheme combined with widow-based and late-based congestion control for multimedia stream. And we also simulate the performance of improved TEAR implementation using NS. With He simulation results, we show that the improved TEAR can provide better fairness and lower rate fluctuations than TCP.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.739-742
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• 2010

The demand of MOST interface module is increasing with car-multimedia network system. MOST devices consist of INIC part which controls MOST network and EHC part which is used by user. The efficient data communication between EHC and INIC demands implementation of a proper device driver. This paper presents a design method for I2C communication driver which is used for transmitting control messages between nodes of MOST network. For effetive I2C communication, we design driver with NetService API. For testing the experiment, we use the MOST audio interface deivce for porting driver sources and will develop various driver on MOST device based OS.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.12
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• pp.2859-2864
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• 2013

Recently, a great attention has been paid to a car black box device in the automobile markets besides it provides an accident re-construction based on the data which contains audio, video, and some meaningful driving information. Also, it is expected that the device will get to promote around public transit and the market will greatly grow within a few years. Thus, this research conducted of preference the influencing factors in decisions purchase of auto black box. Factors influencing in decisions purchase of black box were divided safety, functionality, differentiation, economics. A questionnaire survey was conducted to those who worked in a black box company. This study suggests practical and theoretical implications of factors influencing purchase decisions based on the results.

• The Journal of Information Technology
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• v.9 no.1
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• pp.21-32
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• 2006

Acrophobia is a symptom of feeling an abnormal fear of heights. Medications or cognitive-behavior methods have been mainly used to treat the acrophobia. In these days the virtua1 reality technology has been applied to treat such an anxiety disorders. In this thesis, an telemedicine assistant system for treatment of acrophobia using biomedical signals and virtual reality technique is proposed. I made two virtual reality simulations for treatment of acrophobia and telemedicine system for communication between doctor and patient using personal computer. A virtual environment provides patient with stimuli which arouses phobia, and exposition to such environment makes him have ability to overcome the fear. Recently, the patient can take diagnosis from a medical doctor in distance with the telemedicine system. Multimedia conference service, on-line questionary, signal transfer system are needed to configure such system. Virtual reality simulation system that composed of position sensor, head mount display, and audio system, is also included in this telemedicine system. I added virtual environment update system to this virtual reality telemedicine system for treatment of acrophobia. Former acrophobia treatment systems use only patient's score of the questionary to appraise. The new system developed in this thesis uses not only patient's score of the questionary but also biomedical signals such as HR, GSR amplitude, GSR RT to increase the objectivity and quantitativity. The experimental results show that HR and GSR amplitude are useful for decision of acrophobia. We will apply this system to the acrophobia patient in distance and be able to offer better medical treatment for mental illness in near future.

• Journal of Korea Multimedia Society
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• v.7 no.5
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• pp.668-679
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• 2004

When users of mobile environments move fast or slow into a number of base stations(BS) and request the services of continuous media data such as video or audio, this study examines what the caching has the usefulness in mobile environments. Namely, to reduce packet disconnections and network overheads in mobile environments and minimize transmission delay time, we propose domain-based hierarchical caching structure and study whether application of caching has the usefulness. So we have a model based on user environments and hierarchical network structure to process continuous media services, and analyze the usefulness of caching which depends on the mobile patterns of user and the locations of caching nodes. And then, we research whether caching offers the usefulness in mobile environments. As the result, we are able to see that an adaptable application of caching is needed because the hit ratio and the number of replacement vary in large according to mobile patterns of user and locations of caching.

• Journal of Convergence for Information Technology
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• v.9 no.10
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• pp.101-107
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• 2019

This paper proposes a method for detecting faults in conveyor systems used for transportation of raw materials needed in the thermal power plant and cement industries. A small drone was designed in consideration of the difficulty in accessing the industrial site and the need to use it in wide industrial site. In order to apply the system to the embedded microprocessor, hardware and algorithms considering limited memory and execution time have been proposed. At this time, the failure determination method measures the peak frequency through the measurement, detects the continuity of the high frequency, and performs the failure diagnosis with the high frequency components of noise. The proposed system consists of experimental environment based on the data obtained from the actual thermal power plant, and it is confirmed that the proposed system is useful by conducting virtual environment experiments with the drone designed system. In the future, further research is needed to improve the drone's flight stability and to improve discrimination performance by using more intelligent methods of fault frequency.

• Journal of the Korea Society of Computer and Information
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• v.7 no.3
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• pp.80-91
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• 2002

A general goal of the AT%(Asynchronous Transfer Mode) network is to support connect across various network. On ATM networks, ABR services are provided using the remained ban after allocation CBR and VBR traffic. Realtime services such as transmitting audio or video data may be provided using CBR ado VBR which have a constrained transmission delay, but in these cases, the communications bandwidth may be wasted. In this paper a simulation has been performed to compare and evaluate the performance between the ERICA(Explicit Rate Indicate Avoidance) and EPRCA(Enhanced Proportional Rate Control Algorithm) switches which use Explicit Rate switch algorithm for ABR switch. The variation of the ACR at the source end system, the queue length, the utilization rate of the link bandwidth and the share fairness at the transient and steady states are used as the evaluation criteria for the simulation. As a result of simulation, ERICA algorithm switch was ten times long compared to ERPCA switch to achieve assigned fair share. so EPRCA switch is superior to ERICA about load response. For Fair share and stability, ERICA switch is excellent to EPRCA switch.

• Journal of Korean Academy of Nursing
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• v.49 no.1
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• pp.46-58
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• 2019

Background: Dating violence refers to violence occurring between people in an intimate relationship. Forms of dating violence are often categorized into physical, psychological, and sexual violence, and most existing literature has followed this frame. However, few studies have focused on the phenomenon of living under the perpetrator's coercive control in victims of dating violence, although those experiences are known to be signs of severe forms of violence later on. Purpose: The purpose of this study was to explore the experiences of being coercively controlled in female victims who had experienced dating violence. Method: For this study, in-depth interviews were conducted with a total of 14 female victims, and all interviews were audio-recorded and transcribed. The data were analyzed using the phenomenological analysis method suggested by Colaizzi. Results: Three themes were derived in chronological order: idealizing the relationship (period of potential control), facing severer tyranny (period of coercive control), and escaping from the unending trap (period of post-control). The results showed that the victims experienced perpetrators' control with specific patterns. The perpetrators' controlling behaviors were invisible, literally benevolent, at the beginning; however, severe forms of violence seemed to appear as their relationship deepened and the perpetrators failed to control the victims. Conclusion: Findings from this study presented vivid experiences of female victims who needed help and care. Hopefully, the results can benefit in terms of developing evidence-based prevention strategies for victims as well as assessing the risks of severe forms of dating violence, such as physical attack or murder.