• ETRI Journal
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• 제34권4호
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• pp.613-616
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• 2012

A multi-spot-beam satellite is an attractive technique for future satellite communications since it can support high data rates by projecting high power density to each spot beam and can reuse a frequency in different cells to increase the total system capacity. In this letter, we propose a resource management technique adjusting the bandwidth of each beam to minimize the difference between the traffic demand and allocated capacity. This represents a reasonable solution for dynamic bandwidth allocation, considering a trade-off between the maximum total capacity and fairness among the spot beams with different traffic demands.

• 인터넷정보학회논문지
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• 제19권2호
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• pp.9-15
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• 2018

This paper proposes an energy efficient adaptive relay station ON/OFF scheme with different frequency reuse factors (FRFs) to enhance the system throughput and reduce the transmission energy consumption for the transparent mode of 2-hop cellular relay networks (CRNs) based on orthogonal frequency division multiple access and time division duplex. In the proposed scheme, the base station turns on or off the relay stations (RSs) when they are overutilized and undertuilized based on the traffic density of the cell coverage, respectively. Through the simulation results, we show that the proposed scheme outperforms the conventional CRN in terms of the energy consumption with the same system throughput. Further, in order to increase the system throughput with low energy consumption, the best way is FRF 1 when the number of operating RSs is up to 4 and FRF 2 otherwise.

• 한국광학회:학술대회논문집
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• 한국광학회 2003년도 제14회 정기총회 및 03년 동계학술발표회
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• pp.156-157
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• 2003

The wavelength converter is considered to be a key element of future dense WDM optical networks. It enables wavelength reuse and resolves contention problem. Moreover, the tunability of the wavelength converter enhance the flexibility of network systems by facilitating reconfigurable dynamic wavelength routing. In order to achieve optically tunable wavelength conversion, we recently proposed and experimentally demonstrated wavelength conversion and tuning based on cascaded sum and difference frequency generation in a Ti：PPLN channel waveguide. (omitted)

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2016년도 춘계학술발표대회
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• pp.83-85
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• 2016

C-RAN (Cloud Radio Access Network) structure is the most popular approach for 5G stander, it employs CoMP (Coordinated Multiple Points Transmission/Reception) to enhance frequency utilization and increase throughput for cell-edge users. C-RAN mainly includes two parts: baseband units (BBU) and remote radio heads (RRH). In this paper we propose a new resource block allocation (spectrum allocation) scheme by the permutation and combination of BBUs, and we also use the CoMP (Coordinated Multiple Points Transmission/Reception) technique according to the different environment to improve the spectrum utilization and reduce resource waste in different environment. The simulation results expound that the scheme significantly enhances throughput and improves the spectrum utilization.

• ETRI Journal
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• 제33권4호
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• pp.633-636
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• 2011

In this letter, we propose an overlaid hybrid division duplex (HDD) concept for cellular systems which divides a cell into inner and outer regions and utilizes the merits of both time division duplex (TDD) and frequency division duplex (FDD). The proposed system can take advantage of both TDD and FDD without handover between two duplex schemes. Moreover, it is shown that the proposed HDD system outperforms the conventional TDD or FDD system with mobile relay stations when the synchronization issue is considered in orthogonal frequency division multiple access systems. Thus, the proposed overlaid HDD can be considered as a new framework for future cellular systems.

• 한국정보처리학회논문지
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• 제7권3호
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• pp.901-908
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• 2000

Satellite communication in the 21 century's high tech information world is developing rapidly, marked by high levels of applications and functions. For example, satellite communication can process and switch the speed of the service provided by a broad and vast digital multimedia system such as a long-distance all between nations or broadcasting transfer service, which is supplied by a contemporary satellite system. So, it bring about problems which lack of satellite orbit and gibes out frequency resource by increment of satellite universally. To support this, an OBP satellite system is need, which includes an on-board IF/RF switch, baseband signal processing, multi-beam antenna technology, as well as a simple transponder system. In this paper, we have outlined the next generation of satellite communication; satellite OBP transport network architecture, which offers multimedia service and applied frequency reuse method for multi-spot beam. The satellite B-ISDN transport network architecture is also analyzed.

• 사물인터넷융복합논문지
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• 제7권4호
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• pp.85-94
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• 2021

본 연구는 스크린 골프에서 그래픽 콘텐츠가 제공하는 이미지 느낌, 표현 방법, 이미지 색상의 고려 정도에 따라 소비자가 경험하는 스크린 골프의 콘텐츠 특성, 재이용 의도, 고객 만족, 경제적 가치에 어떠한 차이가 있는지를 검증하였다. 또한 스크린 골프의 콘텐츠 특성이 경제적 가치에 어떠한 영향 관계가 있고, 이러한 과정에서 재이용 의도와 고객 만족이 어떠한 영향이 있는지를 분석하고자 하였다. 2021년 9월 1일부터 9월 30일까지 스크린 골프장을 이용하는 소비자를 대상으로 225부의 설문조사를 실시하였다. 자료 처리는 빈도분석, 요인분석, 신뢰도분석, 군집분석, 카이제곱분석, 3단계 매개회귀분석을 실시하였다. 연구결과는 다음과 같다. 첫째, 선호하는 이미지 느낌은 깔끔하고 세련된 느낌이 높게 나타났고, 선호하는 표현 방법은 사실적 이미지가 높게 나타났으며, 선호하는 이미지 색상은 초록 계열 색상이 높게 나타났다. 둘째, 그래픽 콘텐츠 고려 정도에 따라 경쟁성, 이용 용이성, 유대감, 현실감에서 차이가 나타났고, 소비자의 재이용 의도, 고객 만족, 경제적 가치에서 차이가 나타났다. 셋째, 스크린 골프 콘텐츠 특성과 경제적 가치의 관계에서 고객 만족과 재이용 의도는 매개효과가 나타났다. 이러한 연구를 통하여 스크린 골프의 그래픽 디자인 모형을 도출할 수 있는 기초자료를 제공함으로써 운영 주체의 경제적 효익이 향상될 수 있는 방안을 제시하였고, 스크린 골프 산업이 성장하는데 기여하고자 하였다.

• 서비스연구
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• 제13권4호
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• pp.1-23
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• 2023

현재 태블릿 PC 가 점점 더 인기를 끌면서 매장 운영에 있어 편리함을 제공하지만, 일부 고객은 불만을 느낄 수 있다. 그림자노동의 관점에서 고객은 태블릿 PC 를 사용하는 것이 추가 작업, 즉 서비스 직원으로부터 업무가 이전되어 고객 스스로 작업을 해야 한다고 느낄 수 있다. 따라서 본 연구는 고객이 태블릿 PC 를 이용할 때 그림자노동에 대한 인식(지각된 사용 어려움 및 지각된 사용 강제성)의 원인과 그림자노동에 대한 인식이 태블릿PC 주문 서비스에 대한 재사용 의도에 어떤 영향을 미칠 수 있는지를 조사하는 것을 목적으로 한다. 또한 고객의 그림자노동에 대한 지각이 디지털 리터러시와 정보 과부하에 영향을 받는지 여부를 조사하며, 태블릿 PC 를 사용할 때 발생하는 혜택이 그림자노동 지각에 미치는 긍정적인 영향을 조사한다. 본 연구는 음식점에서 태블릿 PC 를 이용하여 주문하는 고객을 대상으로 중국의 설문조사 전문 사이트인 "원쥬엔싱" (Wenjuanxing)를 통해 온라인 설문조사를 수행한 후, 총 376 개의 유효한 데이터에 대해 SPSS 24.0 을 활용하여 인구통계학적 특성, 빈도 분석, 신뢰도 분석, 타당성 분석, 상관관계 분석 등을 실시했다. 또한 가설들은 회귀분석을 통해 검증하였다. 376 명 응답자의 실증분석 결과, 디지털 리터러시와 정보 과부하가 그림자노동 인식에 영향을 미치며, 태블릿 PC 주문 서비스 재사용 의도에도 영향을 미친다는 점을 밝혔다. 또한 혜택은 이러한 관계에 대해 유의한 조절 효과를 보였다.

• Journal of the Optical Society of Korea
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• 제18권5호
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• pp.459-465
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• 2014

Visible light communications (VLC) using the intensity modulation of light-emitting diodes (LEDs) provides a new communication medium to overcome the shortage of radio spectrum, and allows reuse of LED lighting infrastructures. Orthogonal frequency-division multiplexing (OFDM) was introduced to VLC for its merits in mitigating the fading effects resulting from delay spread, and in avoiding low-frequency ambient interference. Noise and clipping are two major factors that degrade the performance of OFDM in VLC. A larger signal easily overcomes noise, but experiences impairment by clipping. Therefore, degradation due to clipping has a trade-off relationship with that due to noise, depending on the signal amplitude of OFDM. In this paper, the optimal signal amplitude in the trade-off is obtained by simulation when the dimming and LED intensity are given. The former indicates a user's requirement for lighting, and the latter represents the channel quality. The required LED intensity-to-noise ratio, as the channel quality that guarantees dimming as well as an adequate bit-error rate (BER), is also discussed.

• 한국통신학회논문지
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• 제37권8B호
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• pp.677-686
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• 2012

In the presence of a high power cellular network, picocells are added to a Macro-cell layout aiming to enhance total system throughput from cell-splitting. While because of the different transmission power between macrocell and picocell, and co-channel interference challenges between the existing macrocell and the new low power node-picocell, these problems result in no substantive improvement to total system effective throughput. Some works have investigated on these problems. Pico Cell Range Expansion (CRE) technique tries to employ some methods (such as adding a bias for Pico cell RSRP) to drive to offload some UEs to camp on picocells. In this work, we propose two solution schemes (including cell selection method, channel allocation and serving process) and combine new adaptive frequency partitioning reuse scheme to improve the total system throughput. In the simulation, we evaluate the performances of heterogeneous networks for downlink transmission in terms of channel utilization per cell (pico and macro), call blocking probability, outage probability and effective throughput. The simulation results show that the call blocking probability and outage probability are reduced remarkably and the throughput is increased effectively.