• The Transactions of the Korea Information Processing Society
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• v.4 no.2
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• pp.363-376
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• 1997

In this paper, we present a hardware architecture and a sofrware architecture for cimputer based teleconferencing systems.And also we analyse stream adtivation mechanisms for them form the viewpoint of delay. MuX that is a multimedia I/O server provides various processing elements for data I/O, synchronization, interleaving and mixing.We describe methods to build teleconferencing systems with the elements and compares the technique using master click with the techniquie using self clock.In the plase of dta input.the technique using self click is berrer than the technique using master clock.When we generate interleved stream from audio and video stream and activate channel objects by periodic audio stream as activation clock, dealy from imput audio stream to imterleved stream is reduced but delay for video stream is not reduced as much as in the case of audio stream.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.2
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• pp.99-113
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• 1992

In general, TDMA and FDMA have been used for multiple access communication methods. Recently. However, ALOHA and CSMA protocols came to exist as new schemes for VSAT data networks and LANs, respectively. These schemes are proven to be effective for packet switched communication systems that has bursty traffic but packet collisions. In this paper we analyze capture statistics arising from fading channels in packet radio communication systems in the context of ALOHA protocol. We derive general results of the exact form of capture probabilities and present numerical data for wide range of fading parameters. Since the capture probabilities are found to approach zero when the number of transmitted signals become larger, we are able to determine the achievable channel throughput by a least squares fitting of an exponential-type function to the probabilities.

• The KIPS Transactions:PartC
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• v.16C no.1
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• pp.101-108
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• 2009

The data broadcasting service, which is growing remarkably today, provides viewers with useful information as well as high quality video and audio. Service information is a kind of additional data that contains a wide range of information such as channel list and/or program title. Each service information is transmitted in the form of a table. And most standard committees have specified their own table list used for carrying the service information. Consequently, It causes incompatibility among services that each broadcast operators produce because the tables that they use differ from each other. In this paper, we propose a general-purpose service information processing system for an integrated data broadcasting middleware that is compatible with heterogenous broadcasting environments. The system is able to change its target table list dynamically without any code modification. Futhermore, we also adopted a thread pool model for efficient parsing and event dispatching.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.4
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• pp.161-168
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• 2001

Organic thin film transitors(TFTs) are of interest for use in broad area electronic applications. For example, in active matrix liquid crystal displays(AMLCDs), organic TFTs would allow the use of inexpensive, light-weight, flexible, and mechanically rugged plastic substrates as an alternative to the glass substrates needed for commonly used hydrogenated amorphous silicon(a-Si:H). Recently pentacene TFTs with carrier field effect, mobility as large as 2 $cm^2V^{-1}s^{-1}$ have been reported for TFTs fabricated on silicon substrates, and it is higher than that of a-Si:H. But these TFTs are fabricated on silicon wafer and $SiO_2$ was used as a gate insulator. $SiO_2$ deposition process requires a high insulator which is polyimide and photo acryl. We investigated trasfer and output characteristics of the thin film transistors having active layer of pentacene. We calculated field effect mobility and on/off ratio from transfer characteristics of pentacene thin film transistor, and measured IR absorption spectrum of polymide used as the gate dielectric layer. It was found that using the photo acryl as a gate insulator, threshold voltage decreased from -12.5 V to -7 V, field effect mobility increased from 0.012 $cm^2V^{-1}s^{-1}$ to 0.039 $cm^2V^{-1}s^{-1}$ , and on/off current ratio increased from $10^5\;to\;10^6$. It seems that TFTs using photo acryl gate insulator is apt to form channel than TFTs using polyimide gate insulator.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.4
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• pp.1-10
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• 2001

The 3-step cell search has been considered for fast acquisition of the scrambling code unique to a cell in the W -CDMA system. In this paper, the performance of the cell search scheme is analyzed in Rayleigh fading channels. And the system parameters for cell search scheme and the design parameters for the receivers are examined. The probabilities of detection, miss and false alarm for each step are derived in closed forms based on the statistics of CDMA noncoherent demodulator output. Through the analysis, the effect of threshold setting and post detection integration for each step is investigated, and the optimal values of the power allocation for the synchronization channels are also considered. The number of post-detection integrations for each step is a design parameter for the receiver, and the optimum values may depend on not only the power allocation for each channel related to the cell search, but the false alarm penalty time. It is shown that optimal values could be determined through the analysis. Also, the cumulative probability distribution of the average cell search time is obtained.

• Journal of IKEEE
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• v.16 no.2
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• pp.138-144
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• 2012

In this paper, a semi-analytical approach is proposed for DSF(Decode and Selective Forward)-Relay MC-CDMA(MultiCarrier-Code Division Multiple Access) systems over multipath Rayleigh fading channels. Considering BER(bit error rate) performance and complexity, the MMSE-C(Minimum Mean squared Error-per subCarrier) is used as the combining method for MC-CDMA systems. At first, the analytical method based on error-events at relay nodes for DSF-Relay schemes is utilized in order to derive the averaged BER. Then, the averaged BER is expressed as the form considering possible all error-events. Also, proposed semi-analytical expressions have been verified by comparing with simulation results. Finally, it is verified that the derived analytical expressions can be a frame work to cover different multipath Rayleigh fading channel conditions and to measure the upper performance for DSF-Relay MC-CDMA systems.

• The Research Journal of the Costume Culture
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• v.4 no.2
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• pp.219-245
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• 1996

Throughout her life time, Edith Head produced cinema costumes for over one thousand movies. She was the leading cinema costume designer in Hollywood. Since the Academy Awards added the area of costume design to be recognized [during 33 years of her work(1948∼1981)], she was nominated 35 times an awarded eight times. However, there were no significant studies done on her work or accomplishments although she was acknowledged as an ingenue and creative designer who elicited artistic effects by reflect character's images through their costumes. The purpose of the study was focused on revealing Edith Head's life and work as her creations had a great impact in he field of cinema costumes. It was also to emphasize the forceful affect of cinema costumes on fashion and to disclose the powerful influence of cinema costume designers. The method of the study includes reviews of literature, movies for which she created costumes, her own possessions, and fashion magazines as well as her works that were nominated and chosen for the Academy Awards. Edith head's emphasis in costume design was based on a blend of both simplicity and sophistication avoiding excessive exaggeration and transformation in her work. Her work was also realistic and contemporary. She developed a dramatic ambience through an innovative design while preserving the actor's individual character and uniqueness. Through this accept her her work was highly renowned as an art form as it was gaining popularity. She was also a dominant figure who influenced trends in the areas of fashion magazines, uniforms, and public clothing. In the review of her cinema costumes, it was revealed that the styles of cinema costumes can be as quickly adapted by the public as movies are viewed because the cinema costumes are highly projected through a visual channel. Subsequently, a follow up study on the affect of cinema costumes on fashion would be beneficial.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.25 no.3
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• pp.101-122
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• 1999

The history of make-up can go back to the beginning of human being and it can’t be separated from women’s life. The change of history and women's position have given make-up different form and meanings. So make-up becomes another text which can read social·cultural specialty. This study has tried to find out make-up as women culture for women have experienced make-up in a specific situation for a long time and a suit of make-up experience from self-retrospect and made an open channel for women and this paper checked out the possibility of alternative make-up culture. This research used new audience theory of cultural studies which is used for communication study and studied active meaning-construction process and its resistance pleasure. This study saw women as independent subjects not passive victims and how make-up has been different meanings in women’s life. And what pleasure is made and how the way of resistance made constructed in the regulation of make-up.

• Convergence Security Journal
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• v.12 no.3
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• pp.123-129
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• 2012

Due to the high digital technology, various devices such as TV, PC, smartphone, and pad computer are connected to each other using internet and under the circumstance internet services of which the running platforms are mainly PC become "N-screenlized" by extending their service platform to non-PC devices. As a digital TV has outstanding features of being the most influential device in the living room and having the wide spectrum of users, several internet services has been ported on the digital TV platform (in the form of data services) in order to enhance their brand powers. Most of the services, however, failed to get a satisfactory results as the data services are defeated by the broadcasting contents in the competition for the viewer's interests. In the paper, the design guidelines that make data services not to compete with the broadcasting contents are proposed and a prototype of a data service that accommodates the guidelines is introduced. The prototype, called "TV ideal-type world-cup", does not disturb a viewer's watching broadcast contents and channel-changing behavior while it is running and its service flow is designed for a viewer to achieve the goal of service in a few minutes so that the viewer can enjoy the service in a commercial period.

• Journal of Communications and Networks
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• v.18 no.3
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• pp.375-386
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• 2016

Most existing studies on broadcast services in orthogonal frequency division multiplexing (OFDM) systems have focused on how to allocate the transmission power to the subcarriers. However, because a broadcasting system must guarantee quality of service to all users, the performance of the broadcast service dominantly depends on the channel state of the user who has the lowest received signal-to-noise ratio among users. To reduce the effect of the worst user on the system performance, we propose a joint delivery scheme of unicast and broadcast transmissions in OFDM systems with broadcast and unicast best-effort users. In the proposed joint delivery scheme, the BS delivers the broadcast information using both the broadcast and unicast subcarriers at the same time in order to improve the performance of the broadcast service. The object of the proposed scheme is to minimize the outage probability of the broadcast service while maximizing the sum-rate of best-effort users. For the proposed joint delivery scheme, we develop an adaptive power and subcarrier allocation algorithm under the constraint of total transmission power. This paper shows that the optimal power allocation over each subcarrier in the proposed scheme has a multi-level water filling form. Because the power allocation and the subcarrier assignment problems should be jointly solved, we develop an iterative algorithm to find the optimal solution. Numerical results show that the proposed joint delivery scheme with adaptive power and subcarrier allocation outperforms the conventional scheme in terms of the outage probability of the broadcast service and the sum-rate of best-effort users.