• Journal of Korea Multimedia Society
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• v.3 no.6
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• pp.643-651
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• 2000

ATM network technology is generally used for the integration of multimedia services in high-speed Internet. ABR (Available Bit Rate) and UBR (Unspecified Bit Rate) service classes have been developed specifically to support data application. In this paper, through the result of simulation, we analyzed the effect of TCP data transmission performance by using FRR (Fast Retransmission and Recovery) and Nagle's Algorithm on the UBR service, and by adjusting EFCI switch parameter on the ABR service. As a result of our study, performance improvement of TCP over ATM network is observed by adjusting TCP parameters and setting of effective switch parameter.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.986-989
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• 2021

하나의 폰트를 제작하기 위해서, 로마자 폰트는 200여자만 디자인하면 되지만, 한글 폰트는 11,172자나 되는 많은 글자를 하나하나 디자인해야 하는 어려움이 있다. 하나의 한글 폰트 제작에 많은 시간과 노력이 드는 기존 문제점을 해결하기 위해, 메타폰트와 같은 프로그래머블 폰트를 이용하는 방법이 제안되었으나, 이를 실제 사용하는 것은 용이하지 않다. 따라서 이러한 문제를 해결하기 위해 한글 가변폰트 서비스를 위한 한글 매개변수 조절 서비스 "STEMFONT'를 개발하였다. 본 논문에서는 STEMFONT 서비스에 대한 소개와 더불어 서비스 기능에 맞는 인터페이스 구성에 대해 설명한다. 이러한 인터페이스를 통해 사용자들이 쉽게 폰트를 제작할 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9A
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• pp.1285-1294
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• 1999

In this paper we consider the performance of TCP video traffic over ABR with Long-Range Dependent VBR traffic. As compressed coded video traffics are increasing rapidly over Internet, lots of studies are being done for transmitting those traffics efficiently using limited network resources. We consider here the transmitting video service over ABR service in ATM networks, especially satellite networks. CBR or VBR services are suggested in transmitting the video traffic in ATM Forum TM 4.0. But ABR service connection, which is considered as appropriate service for data traffic, can be established with a small amount of bandwidth, MCR (Minimum cell rate). Furthermore ABR service can control the source's transmitting rate using feedback mechanism. Using this feature ABR service can be used in some applications which can control their quality of services corresponding to network loads. Compressed video sources with MPEG-2 are used for Long-Range Dependent VBR traffic here. We model the compressed video source to resemble the MPEG-2 transport streams. These compressed video traffic streams are consisted of three different frames, I-frame, P-frame, and B-frame. So when a network are overloaded, we can control the quality of service using this traffic features. TCP Traffics over ABR need large buffers in ATM switch to satisfy their QoS with background VBR traffics, which have high deviations in bandwidth. Furthermore satellite ATM networks with large feedback delay need large buffers corresponding RTT delay. The performance comparisons among EFCI and ER switch (ERICA+) switches in the network circumstances described above were shown in this paper. We also considered the case with ON-OFF VBR traffics.

• KIISE Transactions on Computing Practices
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• v.21 no.12
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• pp.780-785
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• 2015

Recently HTTP (Hypertext Transfer Protocol) adaptive streaming services have been the subject of much attention. The video quality control scheme of conventional HTTP adaptive streaming services estimates bandwidth using segment throughput and smooths out the sample of segment throughput. However, the conventional scheme has the problem of QoE (Quality of experience) degradation occurring with buffer underflow and frequent quality change due to the fixed number of samples. In order to solve this problem, we propose a video quality control scheme based on segment throughput and buffer occupancy. The proposed scheme determines the number of samples according to the variation of segment throughput. The proposed scheme also controls video quality based on the threshold of bitrate to keep stable buffer occupancy. The simulation results show that proposed scheme improves QoE by preventing buffer underflow and decreasing quality change when compared with the conventional scheme.

• The Journal of Korean Association of Computer Education
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• v.11 no.2
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• pp.79-87
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• 2008

The self-regulated learning was making an alternative idea to improve a learning effect of student who takes part in a study course. This research aimed the self- regulated learning of E-learning system. Also. in this system, the students were able to select the learning object according to the learning method for improving learning effect that students take part in study spontaneously. And the learning logic was implemented for development efficiency and operation by web service. Finally, the test result of study group who had the similar studying level displayed that the proposal method was better learning effect than exist one.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.3843-3848
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• 2011

The purpose of the study was to examine an effect of service delay on waiting anxiety and a moderating role of individual characteristics variables(gender, hedonics). The results of the study were as follows. When waiting time was increased, waiting anxiety was also increased. The data also showed a moderating effect of gender between delay and waiting anxiety, but a moderating effect followed by perceptive level of hedonics for service was nonexistent. In conclusion, the study suggested implications followed by the above results, its limitations and tasks to be solved after the study.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.361-363
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• 2005

최근 컴퓨터 기술의 발전과 더불어 급속하게 발전하는 네트워크 기술이 실생활에 보급되고 네트워크를 통한 멀티미디어 데이터의 교환이나 전송과 같은 서비스들이 활성화 되면서 멀티미디어 데이터가 점점 대용량화 다양화되고 있다. 기존의 멀티미디어 서비스는 정해진 서버로부터 미리 데이터를 받아서 보는 다운로드 서비스가 대부분이었고 스트리밍 서비스라 할지라도 사용자의 기호나 원하는 요구사항에는 미치지 못 하였다. 지금까지 스트리밍 데이터를 전송 하는 프로토콜로 주로 UDP(User Datagram Protocol)를 사용하였다. 하지만 UDP는 혼잡제어를 하지 않으며 현재 인터넷의 주요 트래픽인 TCP(Transmission Control Protocol) 트래픽은 혼잡제어를 한다. 그래서 UDP에 의한 스트리밍 서비스는 TCP 트래픽의 전송률을 저하시키며 더 나아가 네트워크의 전체의 성능을 저하시키는 요인이 될 수 있다. 본 논문에서는 IETF(Internet Engineering Task Force)에서 제정한 실시간 스트리밍 데이터 서비스를 위한 표준인 RTP(Real-Time Transport Protocol)/RTCP(Real-Time Transport Control Protocol)를 적용하여 RTCP의 정보를 가지고 현재 네트워크 상태를 판단하고 스트리밍 서비스를 할 때 데이터의 전송률은 TCP 친화적인 전송률로 조절하는 스트리밍 서비스를 구현하였다.

• The Journal of the Korea Contents Association
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• v.16 no.3
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• pp.376-390
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• 2016

The purpose of present study is to investigate mediating effects of emotional labor in the links between communication ability of small businessmen and customer orientation behavior. In detail, it is demonstrated both impacts of communication ability on customer orientation behavior and emotional labor (surface acting, deep acting), and of emotional labor (surface acting, deep acting) on customer orientation behavior. Furthermore, mediating effects of emotional labor (surface acting, deep acting) will be verified. The data for analysis was collected from 270 employees in small businessmen located in Jeju. The results are as follows. First, the main impacts of communication ability on customer orientation behavior and emotional labor (surface acting, deep acting) were statistically significant, in addition, emotional labor (surface acting) was positively associated with customer orientation behavior. Surface acting as a mediator was partially mediated the relation. The result will help to understand the importance for communication ability in small businessmen, and it suggests the crucial implecation in the communication study of service suppliers.

• Journal of the Korea Convergence Society
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• v.1 no.1
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• pp.17-21
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• 2010

This paper proposes a mechanism for managing overload in real-time web service system. The many previous mechanisms manage overload with controlling web request. These mechanisms can control only new web request. They don't have any control existing tasks, especially periodic tasks. We design a controller that able to meet real-time performance with controlling even periodic tasks. A feedback control system is implemented applying the proposed mechanism. And we verified the stable operation of system.

• Journal of Digital Convergence
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• v.14 no.6
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• pp.119-132
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• 2016

This study examined the concept and usage moderated mediating model in structural equation modeling. The theoretical model and hypothesis were developed based on the Location-Based application's Expectancy disconfirmation, Location-Based application's satisfaction, Location-Based application's continuous usage intention, service trust. The statistical results of the two model were compared: one was free model(positive/negative) and the other was the Moderated Mediating Model(positive/negative). A structure equation model analysis was carried out to test the research model. Further studies are necessary to Ssupport the research hypotheses.