• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.133-134
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• 2014

이동통신망 내에서 셀룰러 주파수를 공유하여 사용하는 D2D(Device-to-Device) 단말들이 밀집한 지역에서는 D2D 단말이 대부분의 자원을 점유하므로 셀룰러 단말이 통신을 할 수 없는 문제점이 있다. 본 논문에서는 이러한 환경에서 셀룰러 통신을 보장하기 위해 셀룰러 단말과 인접한 범위에 있는 일부 D2D 단말에 대한 모드 선택기법을 제안한다. 제안기법은 밀집된 D2D 단말들로 인해 가용자원이 없는 셀룰러 단말의 주변에 있는 D2D 단말을 셀룰러 모드로 전환한다. 이를 통해 셀룰러 단말은 D2D 단말이 밀집한 지역에서 셀룰러 통신에 사용할 자원을 확보하여 셀룰러 통신을 할 수 있다. 시뮬레이션을 통해 이동통신망에서 D2D 밀집지역에 있는 셀룰러 통신의 성능이 향상되었음을 확인하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.594-596
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• 2012

D2D 통신은 이동통신 단말 간 직접통신을 지원함으로써 단말 간 통신 성능과 무선자원의 사용효율을 향상시킬 수 있는 기술이다. 본 논문에서는 D2D 단말이 기존 이동통신망의 무선자원을 재사용하는 경우 발생할 수 있는 간섭의 영향과 그로 인한 이동통신망의 통신성능을 분석한다. 시뮬레이션을 통해 D2D 단말의 위치, 송신전력, 페어 간 거리에 따른 이동통신 및 D2D 통신의 성능변화를 확인하였으며, 해당 결과는 향후 D2D 간섭완화 관련 연구를 위한 참고자료로 활용할 수 있을 것으로 기대된다.

• Journal of the Korean Society for Railway
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• v.13 no.5
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• pp.528-534
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• 2010

In the new growth theory, R&D stock is the third factor of production excluding a labor and capital. In this point, a R&D stock is located in a capital which is accumulated by money like existing capital and this is a knowledge capital. The effort for escalating this knowledge capital is R&D investment and R&D stock is an accumulation of this. A contribution degree of the economic growth and a return of R&D investments are analyzed by an estimation of relation R&D stock and a total factor of productivity. This study analyzed R&D stock of railroad R&D investments and compared R&D stock with a technical level. So, a technical level is proportionally escalated following escalation of R&D stock. and compared railroad industry weight on the GDP with a railroad R&D stock weight on whole industries R&D stock. According to a relatively small railroad R&D stock weight against the railroad industry weight, a continuous railroad R&D investment is needed.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.9
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• pp.18-25
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• 2016

In D2D communications underlaying a multicell network, it is of primary importance to ensure coexistence of cellular links and D2D links with minimal interference. Therefore, resource allocation scheme for D2D links should be designed to limit the interference between cellular links and D2D links. In this paper, we propose an effective resource allocation scheme for multiple D2D links which share the uplink spectrum resource with cellular users in a multicell network. Under the assumption that the locations of users are known to the base station, the proposed scheme allocates cellular resources to D2D links, such that the interference between a cellular link and multiple D2D links is minimized. In particular, we compute two constants from the path loss model and then use the constants to protect both cellular and D2D links. Simulation results are provided to verify the performance of the proposed scheme.

• Smart Media Journal
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• v.4 no.3
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• pp.31-37
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• 2015

Recently, computer graphics has made possible a close representation of the due diligence. But, prefer the feel of a 2D computer graphics. 2D computer graphics and compositing of 3D computer graphics have already been produced for a long time. But, the virtual 3D computer graphics application in 2D image or live-action have been used to effect expression of a 2D computer graphics. Recently, 2D computer graphics content is being expanded through the cartoons. In some cases increase the efficiency by making a 3D computer graphics on the camera angle or temporal and spatial part. Through practical work and want to present the proper direction.

• Journal of Service Research and Studies
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• v.13 no.1
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• pp.144-158
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• 2023

R&D (Research and Development) investment by companies and the government continues to increase, and the total R&D expenditure of public and private sectors in 2021 reached KRW 102 trillion, and the ratio of R&D investment to GDP was 4.96%. It ranks second in the world after Israel. This study analyzes the current status of the domestic R&D service industry and the research and development (R&D) innovation ecosystem based on the business activity survey data of the National Statistical Office in terms of improving R&D productivity of domestic R&D investment that has exceeded 100 trillion won, and analyzes the global R&D service industry and analyzes the global research service industry and R&D service Industry support government policy As a result of the analysis, in the domestic R&D ecosystem, the R&D outsourcing demand of service companies is rapidly increasing, compared to the stagnant R&D outsourcing demand of traditional manufacturing companies. In order to respond to these changing demands for technological innovation, this study suggests balanced support for R&D outsourcing for manufacturing and service companies, expansion of domestic R&D outsourcing, establishment of R&D outsourcing strategies specialized for the service industry, establishment of an open R&D ecosystem, and innovation in connection with materials/parts/equipment strategies.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.12
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• pp.729-738
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• 2014

In this paper, we propose interference avoidance resource allocation scheme based on graph-coloring algorithm to introduce performance gain using spatial reuse in D2D (Device-to-Device) system. By assigning multiple D2D pairs to a single D2D resource, interference from neighboring D2D pairs is inevitable, which leads to performance degradation. Therefore, we first introduce the feedback information and the method considering the amount of information that can be practically provided by a D2D pair. Then, we propose how to construct a graph, which is corresponding to the D2D system, using the feedback information and adopt a graph-coloring algorithm to efficiently avoid interference. Simulation results show that the proposed resource allocation scheme outperforms traditional resource allocation schemes in both overall sum rate and spectral efficiency of D2D system while reducing the outage probability. Moreover, the outage probability, which indicates a failure rate of D2D communication, can be reduced by adopting the proposed scheme.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.4
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• pp.168-180
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• 2018

Due to the spread of mobile devices and the introduction of high-quality services, mobile traffic is expected to increase sharply and overload of cellular networks is expected. D2D communication is a way to reduce the load and evolve to 5th generation. Since D2D communication directly communicates between the terminals, it can reduce the overload of the cellular network and improve energy efficiency, data rate and network performance. This paper proposes a D2D handover scheme for D2D communication in cellular networks. The cellular network is a 3GPP EPS, and the proposed D2D handover method improves the existing EPS handover process considering compatibility between existing EPS and D2D communication. We also demonstrate the superiority of the proposed handover scheme using the network simulator ns-3. Simulation results show that the proposed handover scheme is superior to existing handover methods in terms of CUE variation, packet transmission delay time, and throughput.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.2
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• pp.9-16
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• 2012

In this paper, the beamforming and user scheduling scheme for device-to-device (D2D) underlaying celullar networks with partial channel state information is investigated. In the proposed scheme, cellular users whose channels are nearly orthogonal to the channel between base station and D2D receiver are selected for unitary beamforming so as to minimize the interference to the D2D receiver. The interference caused by underlaying D2D communication can be minimized by reducing the D2D transmitter's transmission power. To enhance the cellular users' throughput further, we also investigate codebook generation method in which each code vector belongs to multiple unitary code matrices. From simulation results, we show that the proposed beamforming and user scheduling scheme mitigates D2D interference to the cellular networks and the codebook generation method improves cellular users' throughput.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.5
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• pp.539-545
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• 2016

In this paper, the use of an amplify-and-forward (AF) helper station in a cellular network with device-to-device (D2D) communication links is considered to enhance D2D rates and control the interference caused by D2D users to the cellular network. Two design criteria for the AF helper station are considered to improve the overall system quality-of-service (QoS). One is maximization of the worst D2D user rate under a constraint on interference caused by D2D users to the cellular network and the other is its dual, i.e., minimization of interference caused by D2D users to the cellular network with minimum rate guarantee for each D2D user. It is shown that the considered problems reduce to semi-definite programming (SDP) problems. Numerical results show that the proposed AF helper station significantly improves the system performance.