• Journal of Satellite, Information and Communications
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• v.9 no.1
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• pp.107-114
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• 2014

The satellite 2.1 GHz frequency bands, 1980-2010 MHz and 2170-2200MHz are allocated for mobile satellite service including satellite IMT, while it does not preclude the use of these bands for mobile services. The concept of an integrated satellite/terrestrial network has been introduced in worldwide because the terrestrial use in these bands adjacent to existing terrestrial IMT bands is attractive to provide mobile broadband services. The integrated satellite/terrestrial infrastructure with a high degree of spectrum utilization efficiency has the ability to provide both multimedia broadband services and public protection and disaster relief solutions. In addition, it is required to consider interference issues between the terrestrial and satellite components in order to reuse the same frequency band to both satellite and terrestrial component. This paper analyzes the interference for satellite uplink in the satellite/terrestrial integrated system and the interference reduction scheme for satellite uplink interfered by terrestrial user equipment.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.81-88
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• 2013

The satellite 2.1 GHz frequency bands, 1980-2010 MHz and 2170-2200MHz are allocated for mobile satellite service including satellite IMT, while it does not preclude the use of these bands for mobile services. The concept of an integrated satellite/terrestrial network has been introduced in worldwide because the terrestrial use in these bands adjacent to existing terrestrial IMT bands is attractive to provide mobile broadband services. The integrated satellite/terrestrial infrastructure with a high degree of spectrum utilization efficiency has the ability to provide both multimedia broadband services and public protection and disaster relief solutions. In addition, it is required to consider interference issues between the terrestrial and satellite components in order to reuse the same frequency band to both satellite and terrestrial component. This paper analyzes the interference for satellite downlink in the satellite/terrestrial integrated system and presents the interference mitigation techniques for satellite mobile earth station interfered by terrestrial base stations.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.208-214
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• 2009

As an advance in medical technology development is being made, and people are increasingly aware of the importance of health, related investments and people's average life expectancy rise, which in turn leads to an increase in elderly people. Also, with a growing number of elderly people enjoying their leisure activities, the utilization of multimedia contents using computers is on the increase, leading to an activated research into the establishment of digital culture for the elderly people. This paper proposes a Korean text input system to enable the elderly to utilize digital contents. Text input interface has conventionally depended on keyboards. However, the keyboard wherein many keys are dispersed creates problems for the elderly, such as a protracted recognition of keys and a lowered concentration when they use the keyboard. To address these problems, in this paper, the grip type controller interface for console games was used and a corresponding alphabet location algorithm was developed. To verify these efforts, a simulator was developed to test 20 elderly people; as a result, their satisfaction over and convenience of using the grip type interface invreased.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.2
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• pp.17-23
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• 2000

Wireless link has high bit error rate compared with wired link and many users share this limited bandwidth. So it needs more powerful error control code and efficient media access control(MAC) to provide multimedia service reliably. In this paper we proposed efficient MAC frame format based on TDMA using mini-slot for request access. The number of mini-slots is variable based on the result of collision in the previous frame. This dynamic allocation of request mini-slots helps resolve the contention situation quickly and avoids the waste of bandwidth that may occur when there are several unneeded request mini-slots. The simulation results are also presented in terms of channel utilization, call blocking probability and cell transmission delay for mixed traffic environment.

• The Journal of Korean Association of Computer Education
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• v.13 no.4
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• pp.27-39
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• 2010

Internet is taking up as a new culture on the cyber-space beyond a simple hobby as its utilization ratio is rapidly being spread throughout the world. However most education for internet media has been focused on cyber ethics education and internet addiction. Therefore it arises to need to educate internet literacy for positive and desirable usage of internet media raises. Previous research on media eduction doesn't have been analyzed the outcome of media education. In this study, we show the result of internet media education which performed for fostering internet literacy. For the analysis of education result we observed emotional attitude about internet, internet media recognition, efficacy of using internet, and consciousness of internet ethics for middle school student. As a result, there are many changes for emotional attitude about internet, ability of using internet media, and consciousness of internet ethics.

• 전자공학회논문지 IE
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• v.44 no.4
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• pp.48-54
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• 2007

Due to the diverse utilization of multimedia, interests are increasing towards processing (saving, editing, searching, etc) three dimensional object data. This paper proposes and realizes a retrieval system for three dimensional objects using reflective symmetry. For the retrieval method, a reflective symmetric axis with a projector is used. The symmetric plane is calculated by the reflection symmetry, and the depth buffer is calculated for the symmetric plane. Then, by applying the Fourier Transform to the depth buffer, the feature vector for the object is generated and retrieved. For the sample of inquiry, the model of similar symmetry was extracted using the benchmark data from Konstantz University. Considering that most of the objects have symmetrical characteristics, the proposed method of retrieving three dimensional objects using a reflective symmetric surface is an outstanding retrieval system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.6
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• pp.275-280
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• 2013

Recently, access networking BroadBand the high performance of the video equipment to the Internet via voice, video, multimedia services, such as dealing with the media information dissemination is becoming increasingly attracting attention. More video devices and network environments in the future to keep pace with the high-quality video using the form dealing with an increasingly diversified and shall utilization is expected. Among them, video encoding technology, image compression encoding technology of information technology is one of the central role. Video coding technology that requires a vast amount of information contained in the video signal and the appropriate amount of information to eliminate redundancy as the efficiency of the digital code representing video signal is developed as a technology is going. Therefore, this study applied to video coding mode selection in the cost evaluation methods to examine and to maximize the coding efficiency and the proposed method compared to the conventional method was confirmed excellence.

• Journal of Communications and Networks
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• v.7 no.3
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• pp.313-324
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• 2005

The success of the IEEE 802.11 standard has prompted research into efficiency of the different medium access methods and their support for different traffic types. A modified version of the point coordination function (PCF) called modified PCF has been introduced as a way to improve the efficiency over the standard method. It has been shown through a simulation study and a mathematical analysis that channel utilization can be much improved compared to the standard, in case there is no so-called hidden station problem. However, under the hidden station problem, the efficiency of the modified PCF would obviously decrease. In this paper, some enhancements of the modified PCF are introduced. Firstly, we propose a retransmission process to allow frames involved in collisions to be retransmitted. Then, we propose a collision resolution mechanism to reduce the frame collision probability due to the hidden station problem. In addition, we propose a priority scheme to support prioritization for different traffic types such as interactive voice and video, and real-time data traffic in the modified PCF. To prevent the starvation of one low priority traffic, minimum transmission period is also guaranteed to each traffic type via an admission control algorithm. We study the performance of the modified PCF under the hidden station problem and the performance of the modified PCF with priority scheme through simulations. To illustrate the efficiency of the priority scheme, we therefore compare its simulation results with those of some standardized protocols: The distributed coordination function (DCF), the enhanced distributed channel access (EDCA), the PCF, and our previously proposed protocol: The modified PCF without priority scheme. The simulation results show that the increment of delay in the network due to the hidden station problem can be reduced using the proposed collision resolution mechanism. In addition, in a given scenario the modified PCF with priority scheme can provide better quality of service (QoS) support to different traffic types and also support a higher number of data stations than the previous proposals.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8A
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• pp.1195-1207
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• 1999

Wireless channel has high error rate and limited bandwidth. In order to guarantee the quality of service for multimedia through wireless channel, wireless ATM network requires the cell structure with error control schemes and an efficient medium access control protocol. In this paprt, an efficient medium access control protocol, which is considered of cell structure and the QOS, is proposed for wireless ATM networks. Many kinds of ATM cell structures are analyzed in terms of cell error rate and cell loss rate to choose the proper cell structures for this proposed MAC protocol. And a bandwidth allocation algorithm is also designed to satisfy the priority of services. The performance of proposed MAC protocol are evaluated in terms of channel utilization, call blocking and packet discard probability accotding to different kinds of cell structure through simulation.

• Journal of the Korea Fashion and Costume Design Association
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• v.10 no.3
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• pp.111-126
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• 2008

This article aims to discover the current status and appropriate way to research Gyubang craft, expecting its development and preservation, and elevating it to Korea's unique artistic textile culture. It also searches improved methods for Gyubang craft as the following: First, in order to avoid confusions about Gyubang craft, appropriate concepts and definitions of Gyubang craft must be settled through a discussion among experts. Second, by activating economic activities at lower ratio, among purposes of Gyubang craft, achievements must be elevated. Third, in order to settle down the difficulties of Gyubang craft, a variety of methods such as effective sewing machines and manufacturing techniques as well as providing materials at a reasonable price, considering practical ways through diversifying products, elevating the economy of crafts, exploring sales routes, improving educational contents, and expanding educational places must be facilitated. Fourth, for nurturing talented and excellent human resources in the area of Gyubang craft, the followings should be considered: diversifying contents of education, developing textbooks, improving instructors' quality, providing reasonable cost of education, educating on the utilization and application of Gyubang craft, introducing efficient teaching methods through textbooks and multimedia, awarding 'certificates' to trainees, and permitting certificate holders' to instruct Gyubang craft. Finally, it is convinced that the achievement of production, pride of preserving tradition, pleasure of procedural work, economic activities as experts, and sales of products will be reinforced, and the population for Gyubang craft is also expected to increase. By elevating Gyubang craft into Korea's traditional textile art, Korea's global competitiveness in the area of textile should be strengthened.