• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.372-374
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• 2012

급속도로 증가하는 모바일 데이터 트래픽으로 인해 현재 이동통신 기술에서 모바일 트래픽 감소와 네트워크 효율 증대가 가능한 기술이 필요시 되고 있다. D2D 통신은 인접한 기기간의 직접 통신을 지원함으로써 기지국에서의 트래픽 과부하를 분산시키고 기기 간 인접함을 이용해 놓은 전송속도, 낮은 전송시간, 낮은 전력소모의 이득을 얻을 수 있으며 기지국을 이용한 통신과의 주파수 재사용으로 인한 자원 재활용 이득을 얻을 수 있다. 이러한 이점으로 인해 D2D는 차세대 이동통신 기술의 중요한 요소로 여겨지고 있으며 표준화 단체와 여러 기업에서 D2D를 활용한 차세대 이동통신 기술을 개발하는데 많은 투자를 하고 있다. 본 논문에서는 D2D에 대한 설명과 Qualcomm 사의 D2D 기술인 FlashLinQ, Nokia 사의 D2D 통신기술에 대하여 알아보고 미래 이동통신 환경에서 D2D 기술을 활용한 다양한 서비스 시나리오를 분류하고 이에 대한 요구사항을 정리해 봄으로써 D2D를 활용한 이동통신기술 개발의 초석을 마련한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.40-42
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• 2015

Our D2D (Device-to-Device) advertisement dissemination algorithm based on the convergence of a D2D communication and a social commerce service is able to efficiently deliver advertisement messages of small business owners. We here assume high user-density areas as target-areas, and these target areas can form several target-groups based on geographical proximity. Also, the isolated target-areas which are not included in the target-groups may have the opportunities for forming a new target-group in consideration of the maximum distance with AP. In this paper, we evaluate performances with respect to the total number of successfully received users and the average number of relay users in accordance with variation in the maximum distance for isolated target-areas.

• Journal of Communications and Networks
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• v.18 no.3
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• pp.429-438
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• 2016

In this paper, we investigate an interference mitigation scheme by antenna selection in device-to-device (D2D) communication underlaying downlink cellular networks. We first present the closed-form expression of the system achievable rate and its asymptotic behaviors at high signal-to-noise ratio (SNR) and the large antenna number scenarios. It is shown that the high SNR approximation increases with more antennas and higher ratio between the transmit SNR at the base station (BS) and the D2D transmitter. In addition, a tight approximation is derived for the rate and we reveal two thresholds for both the distance of the D2D link and the transmit SNR at the BS above which the underlaid D2D communication will degrade the system rate. We then particularize on the small cell setting where all users are closely located. In the small cell scenario, we show that the relationship between the distance of the D2D transmitting link and that of the D2D interfering link to the cellular user determines whether the D2D communication can enhance the system achievable rate. Numerical results are provided to verify these results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.3
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• pp.1311-1324
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• 2019

In the traditional cellular network communication, the cellular user and the base station exchange information through the uplink channel and downlink channel. Meanwhile, device-to-device (D2D) users access the cellular network by reusing the channel resources of the cellular users. However, when cellular user channel conditions are poor, not only D2D user cannot reuse its channel resources to access the network, but also cellular user's communication needs cannot be met. To solve this problem, we introduced a novelty D2D communication mechanism in the downlink, which D2D transmitter users as half-duplex (HD) relays to assist the downlink transmission of cellular users with reusing corresponding spectrum. The optimization goal of the system is to make the cellular users in the bad channel state meet the minimum transmission rate requirement and at the same time maximize the throughput of the D2D users. In addition, i for the purpose of improving the efficiency of relay transmission, we use two-antenna architecture of D2D relay to enable receive and transmit signals at the same time. Then we optimized power of base station and D2D relay separately with consideration of backhaul interference caused by two-antenna architectures. The simulation results show that the proposed HD relay strategyis superior to existing HD and full-duplex (FD) models in the aspects of system throughput and power efficiency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.2
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• pp.483-503
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• 2015

This paper analyzes the optimal user density and power allocation for Device-to-Device (D2D) communication underlaying cellular networks on multiple bands with the target of maximizing the D2D transmission capacity. The entire network is modeled by Poisson point process (PPP) which based on stochastic geometry. Then in order to ensure the outage probabilities of both cellular and D2D communication, a sum capacity optimization problem for D2D system on multiple bands is proposed. Using convex optimization, the optimal D2D density is obtained in closed-form when the D2D transmission power is determined. Next the optimal D2D transmission power is obtained in closed-form when the D2D density is fixed. Based on the former two conclusions, an iterative algorithm for the optimal D2D density and power allocation on multiple bands is proposed. Finally, the simulation results not only demonstrate the D2D performance, density and power on each band are constrained by cellular communication as well as the interference of the entire system, but also verifies the superiority of the proposed algorithm over sorting-based and removal algorithms.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.4
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• pp.611-619
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• 2008

2.5D Mapping system that embody in this paper can make new design by doing draping to live various texture and model picture image of fashion clothes by pattern, and can confirm clothes work to simulation without producing direction sample or product directly. Also, the system can support function that can forecast fabric design and state of end article exactly, and the system can bring competitive power elevation of fashion industry and cost-cutting effect by doing draping using database of fabric and model picture image. 2.5D Mapping system composed and embodied by mesh warp algorithm module, light and shade extraction and application module, mapping path extraction module, mesh creation and transformation module, and 2.5D mapping module for more natural draping. Future work plans to study 3D fashion design system that graft together 3D clothes technology and 3D human body embodiment technology to do based on embodiment technology of 2.5D mapping system and overcomes expression limit of 2.5D mapping technology.

• Microbiology and Biotechnology Letters
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• v.26 no.3
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• pp.250-256
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• 1998

D-Tagatose production from D-galactose was investigated using 35 type strains of American Culture Type Collection (ATCC) and Korean Collection for Type Cultures (KCTC) which have potential to produce D-tagatose. Enterobacter agglomerans ATCC 27987 was selected as a D-tagatose producing strain due to its short fermentation time and high production of D-tagatose. Optimization of the culture conditions for D-tagatose production by E. agglomerans ATCC 27987 was performed. Among various carbon sources, D-galactose was the most effective carbon source for D-tagatose production. As the D-galactose concentration was increased, cell growth and D-tagatose production increased. Effect of nitrogen sources on D-tagatose production was studied. Of inorganic nitrogen sources, ammonium sulfate was effective one for D-tagatose production and yeast extract was the most suitable organic nitrogen nutrient. The concentrations of inorganic compounds such as KH$_2$PO$_4$, K$_2$HPO$_4$, and MgSO$_4$$.$7H$_2$O were also optimized for D-tagatose production. The optimal medium was determined to contain D-galactose of 20 g/l, yeast extract of 5.0 g/l, (NH$_4$)$_2$SO$_4$ of 2.0 g/l, KH$_2$PO$_4$ of 5.0 g/l, K$_2$HPO of 5.0 g/l, and MgSO$_4$$.$7H$_2$O of 5 mg/l. The optimal environmental conditions in a 250-$m\ell$ flask were found to be pH of 6.0, temperature of 30$^{\circ}C$, and agitation speed of 150 rpm. D-tagatose of 0.41 g/l could be obtained in 24 h from 20 g/l D-galactose at the optimal culture condition without induction and cell concentration.

• The Journal of the Korea Contents Association
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• v.10 no.6
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• pp.222-235
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• 2010

After its remarkable success, "Avatar" brought another way of creating cinematic story; the stereoscopic 3-D cinema. Comparing conventional 2-D filmmaking, you need twice as much of budget and manpower in 3-D filmmaking because of the complicated process and slow production speed. The 3-D hardware like 3-D TV and 3-D projector are already showing at the retail stores while 3-D filmmaking is still in veil, and no major educational institution is yet to start 3-D related education. As 3-D movies get popular and demand more 3-D filmmaking professional crew, educating 3-D filmmaking to 2-D based film students will improve their hiring rate in the market. The successful result of the box office showing 3-D films like "Alice in Wonderland 3D" and "Titan 3D" forecasts that there will be more demand on 3-D related jobs very soon.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.11
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• pp.1315-1321
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• 2004

Quantitative performance test on the conventional 2D-PIV and the hybrid angular 3D-PIV(Stereoscopic PIV) was carried out. LES Data sets on an impinging jet which are provided on the webpage(http://www.vsj.or.jp/piv) for the PIV Standard Project were used for the generation of virtual images. The generated virtual images were used for the 2D-PIV and 3D-PIV measurements test. It has been shown that the results obtained by 2D-PIV on average values are slightly closer to the LES data than those obtained by 3D-PIV, but the turbulent properties obtained by 2D-PIV are largely underestimated than those obtained by 3D-PIV.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2021.06a
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• pp.16-18
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• 2021

미디어 기술은 사용자가 더욱 몰입감을 느낄 수 있는 방향으로 개발되어 왔다. 이러한 흐름에 따라 기존의 2D 이미지에 비해 깊이감을 느낄 수 있는 증강 현실, 가상 현실 등 3D 공간 데이터를 활용하는 미디어가 주목을 받고 있다. 포인트 클라우드는 수많은 3차원 좌표를 가진 여러 개의 점들로 구성된 데이터 형식이므로 각각의 점들에 대한 좌표 및 색상 정보를 사용하여 3D 미디어를 표현한다. 고정된 크기의 해상도를 갖는 2D 이미지와 다르게 포인트 클라우드는 포인트의 개수에 따라 용량이 유동적이며, 이를 기존의 비디오 코덱을 사용하여 압축하기 위해 국제 표준기구인 MPEG(Moving Picture Experts Group)에서는 Video-based Point Cloud Compression (V-PCC)을 제정하였다. V-PCC는 3D 포인트 클라우드 데이터를 직교 평면 벡터를 이용하여 2D 패치로 분해하고 이러한 패치를 2D 이미지에 배치한 다음 기존의 2D 비디오 코덱을 사용하여 압축한다. 본 논문에서는 앞서 설명한 2D 패치 이미지에 super resolution network를 적용함으로써 3D 포인트 클라우드의 성능 향상하는 방안을 제안한다.