• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.12
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• pp.2534-2542
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• 2011

In this paper, we show that performance can be improved by using multiple antennas in the conventional orthogonal code hopping multiplexing (OCHM) scheme, which was proposed for accommodating a larger number of users with low channel activities than the number of orthogonal codewords used in code division multiple access (CDMA)-based communication systems through downlink statistical multiplexing. First, we introduce two different types of OCHM systems together with orthogonal codeword allocation strategies, and then derive their mathematical expression for log-likelihood ratio (LLR) values according to the two different schemes. Next, when a turbo encoder based on the LLR computation is used, we evaluate performance on the frame error rate (FER) for the aformentioned OCHM system. For comparison, we also show performance for the existing symbol mapping method using multiple antennas, which was used in 3GPP standards. As a result, it is shown that our OCHM system with multiple antennas based on the proposed orthogonal codeword allocation strategy leads to performance gain over the conventional system---energy required to satisfy a target FER is significantly reduced.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.4
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• pp.99-107
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• 2009

Visible Light Communication (VLC) is a promising wireless communication technology. It offers huge, worldwide available and free bandwidth without electro-magnetic interference, which makes it very attractive for RF-sensitive operating environments. We propose colored LED-based VLC system for hospital use which includes voice recognition system for operating the medical equipments. New Mr hlation Scheme based on the Light Color Space is suggested to overcome the effect of noise generated by background light. Different color space constellations for different symbol sizes are also suggested which would give better bit error rate performance. Finally, Slotted ALOHA or TDMA medium access control protocols are suggested for multi-user operations.

• The Korean Journal of Archival Studies
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• no.40
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• pp.225-277
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• 2014

This essay focused on mapping out the next archiving model during 15 years. This metaphorical 'JINGU PROJECT' is titled from Shinto relation in Japan rebuilding every 20 years. We need some kinds of self sustainable growth archiving model. It means that it's time to say about our archiving experiences in field for archiving technics and knowledges. We should know the fact that a few thousands archivists have been acting ih fields. Since 1999, we have tried to build up the best practices in public offices. So far, So good. However, we need another wing for better flying from now on. I believe in the power of silences in field because they will speak up their voices.

• Fashion & Textile Research Journal
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• v.24 no.1
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• pp.1-14
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• 2022

K-pop stars are an important influence in the era of digital culture based on emotions. The purpose of this study is to visually express the identity and worldview of their music in the virtual and real world, and to promote Korea's current and past culture. The study also intends to appeal to the emotions of the global fans by designing original textile in their music video 'IDOL' on Tiny TAN - a symbol of world pop star BTS. For design development, traditional Korean images shown in the 'IDOL' video were collected, patterns for each member were selected, and a motif was designed on Adobe Illustrator. We selected the dragon as the motif for V, cloud for Suga, chrysanthemums for Jin, mask for Jung Kook, hanok pavilion for RM, fan for Jimin, and Sam Taegeuk for J-Hope. The selected motifs were designed as per the four textile design arrangement methods: square pattern, 1/2 half drop pattern, turn-around pattern, and panel pattern. The design was presented by mapping Kwaeja to Tiny TAN character. The developed textile design can be used not only for character costumes in virtual space, but also for various products such as clothes, accessories, bedding, cosmetics, stationery, and food. By using it to produce goods inspired by K-pop stars, it can be used as basic data for the development of high value-added competitive products in the global market and create synergy effects of K-Design, which would lead a new trend in the design world.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.3
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• pp.1-8
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• 2009

DS-CDMA system has very low bandwidth efficiency, hence it is difficult to maintain high spreading gain for high speed data transmission. Offset stacked spreading CDMA(OSS-CDMA) is a transmission scheme where spreading codes with chip offsets are overlapped, then transmitted. This kind of system requires a code set that guarantees orthogonality between codes in the set of any cjip offset. An orthogonal complementary code set has a property that the crosscorrelation function between codes in the group is zero for all shifts, hence it can be used for an OSS-CDMA system. In an OCC-OSS CDMA system each user is assigned an orthogonal complementary code group. User data bit is spread by the given codes and overlapped, and the code sequences are transmitted with multicarrier. However, the offset stacked spread sequences are multilevel, and the number of symbol levels is increases as the spreading efficiency is increased. When the OSS sequence is transmitted with MPSK mapping, the signal constellation becomes dense, and the system is easily affected by channel impairments. In this paper, we propose a level clipping scheme on OSS sequence before MPSK modulated. Simulations have been carried out to investigate the BER performance of the OCC-OSS CDMA system in AWGN environment. The results show that proposed scheme outperform the scheme without level clipping.