• Journal of Broadcast Engineering
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• v.24 no.4
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• pp.613-622
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• 2019

A differential codebook design method using wireless channel's temporal correlation is proposed over closed loop multiple-input single-output (MISO) system. The single layer codewords in a codebook are selected among a set of phase elements. In the conventional codeword selection rule, codewords are assumed to be on a spherical cap and sine formula was used. In this paper, however, a new method using Pythagoras formula is employed to simplify computational complexity. Also, an adaptive differential codebook selection is adopted to enhance performance. Monte-Carlo simulations demonstrate that the proposed codebook is superior to the conventional ones.

• 프린팅코리아
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• v.9 no.10
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• pp.126-127
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• 2010

이 책의 저자 4명은 문화체육관광부의 전자출판산업 육성 정책연구 TFT의 위원과 부서 담당자로서 몇 달 동안 TFT에 참여하면서 외국에 비해 전자책 시장 반응이 미진한 국내 현실을 직시, 국내 전자책 시장의 활성화에 일조하고자 책을 집필하게 되었다.

• The Journal of the Korea Contents Association
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• v.16 no.2
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• pp.1-13
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• 2016

The purpose of this study is to explore the emotions of Facebook. Various types of emotions are being exchanged on Facebook. The emotional reactions make the Facebook different from previous electronic bulletin board. According to previous researches, computer-mediated communication can deliver visual symbols and non-verbal cues to enhance the abundance of meanings. Data were collected from 205 Facebook users and the number of users' posts were total 10308. The contents analysis was conducted to explore emotions of the 10308 Facebook posts. The results showed that the most frequent emotion was pleasure. The emotional distributions were different according to the contents types; text, video, photo, and link. For the text content type, emotion of curiosity was apparent and for the photo content type, emotion of love was more frequent than others, and for the video content type, emotion of surprise was salient. The results of the analysis for the shared contents also revealed that pleasure and hope were more frequent emotions than other emotions.

• Proceedings of the Korean Society of Computer Information Conference
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• 2015.07a
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• pp.289-292
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• 2015

본 작품은 학생들이 만든 캡스톤디자인 작품이다. 본 작품의 기획의도는 특정한 형식에 구애받지 않고 자신만의 생각을 텍스트뿐만 아니라 여기에 사진과 동영상 등의 다양한 멀티미디어를 함께 첨부할 수 있는 스토리앱 형식의 전자책을 개발하고자 한다. 이 전자책은 디자인 템플릿을 통해 예쁘게 꾸밀 수 있으며, 본인이 담고 싶은 글을 책으로 만들고, 이렇게 만들어진 개성 있는 전자책은 상대방에게 공유를 통해 선물할 수 있는 어플리케이션으로 개발한다. 따라서 본 연구는 개성 있는 포토북을 자유롭고 쉽게 만들 수 있는 환경 구현 즉, CMS에 그치지 않고 개인의 소중한 추억을 타인들에게 공유함으로써 감동을 나눌 수 있게 하는 것이 최종 목표이다. 또한 모바일에서만 공유로 끝나는 것이 아닌 pc로도 전송 가능하기 때문에 만들어진 결과물을 출력 후 종이책으로 제본해 보관할 수 있는 서비스 역시 기대해 볼 수 있겠다.

• The Journal of the Petrological Society of Korea
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• v.18 no.4
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• pp.293-305
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• 2009

The Gilan-Cheongsong area, which is in contact with Yeongyang and Uiseong Blocks of Gyeongsang Basin, Korea, consists of Precambrian metamorphic rocks, Triassic Cheongsong granite, Cretaceous sedimentary rocks(Iljik, Hupyeongdong, Jeomgok Formations), and Cretaceous igneous rocks(andesite, quartz porphyry, felsite). In this area are developed faults trending in (W)NW, NNW, ENE, NS, (N)NE directions which are representative in the Gyeongsang Basin. We analyzed the geometric and kinematic characteristics of fracture systems to inquire into movement history and sense of these faults in this area. This study suggests that these faults were mainly strike-slip movement. The orientations of fracture sets show ENE, NNW, (W)NW, (N)NE, NS in descending order of frequency. Their prolongation presents (W)NW, NNW, ENE, (N)NE, NS in descending order of predominance, and also agrees with that of faults in this area. The development sequence and movement sense of fracture sets are summarized as follows; (1) (W)NW: dextral shearing $\rightarrow$ (2) (W)NW and NNW: conjugate shearing(the former: dextral, the latter: sinistral) $\rightarrow$ (3) NNW: dextral shearing $\rightarrow$ (4) (W)NW: sinistral shearing $\rightarrow$ (5) ENE: dextral shearing $\rightarrow$ (6) ENE and NS: conjugate shearing(the former: sinistral, the latter: dextral) $\rightarrow$ (7) (N)NE: sinistral shearing, and this result is closely associated with the development sequence and movement sense of faults developed in this area.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.5
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• pp.7-14
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• 2012

The quantized beamforming systems always need the channel state information, which must be quantized into a finite set of vectors (named codebook), and feedback only sends the index representing the desired vector. Thereby it minimized the impact of feedback errors, caused by feedback overhead and delay. In this regard, index assignment (IA) methods, an exhaustive-search and group-based schemes, have been presented for minimizes the performance degradation without additional feedback bits. In this paper, we proposed enhanced group-based IA method, which used the optimal codebook design with chordal distance, having the adaptive properties in application of the existing IA methods. When the number of transmit antennas is 4 and LTE codebook is used, Monte-Carlo simulations verify that the proposed scheme has a power advantage of 0.5~1dB to obtain the same bit error rate than methods without IA, and it has 0.1~0.2 dB better performance compared with the existing IA methods over same environment.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.5
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• pp.37-43
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• 2012

The closed-loop multiple-input multiple-output (MIMO) system has been adopted by long term evolution (LTE) system. Many techniques are proposed to enhance the transmission of LTE's advanced version to meet the increasing requirement, in which differential codebook gains a lot of interest. Previous researches on designing differential codebooks focused on quasi-diagonal unitary matrix which cannot guarantee the equal gain property. The equal gain property is very important to uplink because the performance of uplink is very sensitive to the peak-to-average power ratio (PAPR). In this paper, we derive the analytical expression of average bit error rate and PAPR for differential precoding MIMO system. Using the analytical results, we investigate the performances of several differential precoding schemes considering non-linear amplifier at the transmitter. Some selected simulation results indicate that the conventional differential precoding schemes have good performances without the consideration of non-linear amplifier. While considering non-linear amplifier, the proposed differential codebook outperforms other differential precoding schemes because it maintains the equal gain per transmit antenna.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.1
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• pp.24-31
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• 2015

A differential codebook using M-ary phase shift keying (M-PSK) constellation as its codeword elements, is proposed for Long term evolution (LTE), LTE-Advanced (LTE-A), and/or WiMAX systems. Due to the temporal correlation of the adjacent channel, the consecutive precoding matrices are likely to be similar. This approach quantize only the differential information of the channel instead of the whole channel subspace, which virtually increase the codebook size to realize more accurate quantization of the channel. Especially, the proposed codebook has the same properties of LTE release-8 codebook that is, constant modulus, complexity reduction, and nested property. The mobile station can be designed by using a less expensive non-linear amplifier utilizing the constant modulus property. Computer simulations show that the capacity of the proposed codebook performs better than LTE release-8 codebook with the same amount of feedback information.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.1
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• pp.70-76
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• 2011

LTE Re1-10 aims at peak. data rates of 1Gbits/s for the downlink and 500 Mbits/s for the uplink, which can be accomplished by not only wide spectrum but also advanced MIMO techniques such as precoded MIMO and cooperative relays. Considering some relays can have more direct signal paths than mobile stations do, LoS components are examined to build more efficient codebooks for Rician channels. The proposed codebooks perform better than the existing LTE codebooks as the criterium of LoS, K-factor increases. Conserving the advantages and max-min chordal distance of the existing LTE codebooks, the proposed ones also maximize the minimum chordal distances between codewords over Rician fading channels. Link-level simulation with LTE system parameters confirm the performance improvements as the value of K increases.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.7
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• pp.22-30
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• 2015

For long-term evolution (LTE) MIMO transmission, codebooks are used to utilize the estimated channel information under the limited feedeback environment, and related study has been actively performed. Existing codebooks include codevectos constructed based on vector quantization (VQ) and discrete Fourier transform (DFT), and the LTE standard specifies codebooks modified from these examples to support up to 8 transmit antennas. As the number of antennas increases and as the spatial channel model is used as a standard environment to evaluate the LTE transmission performance, new beamforming methods as well as codebook designs are needed. In this paper, we implement the 3-dimensional spatial channel model (3D-SCM) to analyze the key statistical characteristics of the generated channel, and present efficient ways of determining corresponding codebooks. In particular, we propose a nonuniform-phase DFT-based codebook to improve the existing uniform-phase DFT-based codebook, and evaluate its performance under the given SCM transmission environment. There exists a strong tendancy in statistical distributions of the phase difference between adjacent antenna elements for the SCM, which can be appropriately exploited in codebook design to produce a performance gain over the existing design.