• 한국통신학회논문지
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• 제41권5호
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• pp.539-545
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• 2016

이 논문에서는 단말 간 직접 통신(Device-to-Device: D2D) 링크가 있는 셀룰러 망 안에서 증폭 후 전달 (Amplify-and- Forward: AF) 방식의 조력국을 사용하여 D2D 전송률을 높이고 D2D 단말기가 셀룰러 망에 미치는 간섭을 제어하는 방법을 제안한다. 전체 시스템의 quality-of-service (QoS)를 높이기 위해 두 가지 방법으로 조력국을 설계한다. 첫 번째는 D2D 단말기가 셀룰러 망에 미치는 간섭을 제한하면서 최저 D2D 전송률을 최대화하는 문제이고, 두 번째는 이것의 dual 문제인 각 D2D 단말기의 최소 전송률을 보장하면서 D2D 단말기가 셀룰러망에 미치는 간섭을 최소화하는 문제이다. 또한, 이 문제들은 semi-definite programming (SDP) 문제로 바뀔 수 있음을 보인다. 실험 결과에서는 AF 조력국이 시스템의 성능을 획기적으로 향상시킬 수 있음을 보인다.

• 한국정보과학회논문지:정보통신
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• 제35권5호
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• pp.425-436
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• 2008

본 논문에서는, WLAN과 셀룰러망의 중첩된 환경에서 망자원을 효율적으로 하는 호수락제어 방식을 제안한다. 제안된 방식은 비실시간 트래픽을 WLAN으로 분산 이동시킴으로써 셀룰러망의 혼잡도를 완화시킨다. 제안된 호수락제어 방식에 대해서 수치 분석과 시뮬레이션 분석을 한다. 시뮬레이션 결과로써, 제안된 호수락제어 방식이 기존의 방식보다 좋은 성능을 보여준다. 특히, 실시간 트래픽 보다 비실시간 트래픽의 높은 입력 트래픽율에 대해서 좀 더 안정적인 QoS를 유지할 수 있다.

• 한국콘텐츠학회논문지
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• 제4권4호
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• pp.113-121
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• 2004

기존 셀룰러 IP는 많은 중복패킷으로 인하여 네트워크에 큰 트래픽 부하가 가중되고, 패킷 손실과 핸드오프 지연이 발생한다. 본 논문에서는, 페이징 캐시와 라우팅 캐시를 결합한 통합 캐시와 중복 패킷 발생을 최소화하는 개선된 적응형 세미소프트 핸드오프를 함께 운용할 것을 제안하였다. 컴퓨터 시뮬레이션을 통하여 패킷 손실, 핸드오프 지연 및 네트워크 내 트래픽 부하 특성 등을 고찰하였다. 그 결과, 제안한 방식은 액세스 네트워크 내 노드와 이동 호스트의 수, 노드 내 다운링크의 수가 증가할수록 세미소프트 핸드오프를 적용한 기존의 셀룰러 IP와 비교하여 크게 개선되었다는 것을 확인하였다.

• Journal of Communications and Networks
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• 제8권1호
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• pp.13-20
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• 2006

In cellular mobile communications, how to achieve optimum system capacity with limited frequency spectrum is one of the main research issues. Many dynamic channel assignment (DCA) schemes have been proposed and studied to allocate the channels more efficiently, thus, the capacity of cellular systems is improved. Reuse partitioning (RP) is another technique to achieve higher capacity by reducing the overall reuse distance. In this paper, we present a network-based DCA scheme with the implementation of RP technique, namely dynamic reuse partitioning with interference information (DRP-WI). The scheme aims to minimize the effect of assigned channels on the availability of channels for use in the interfering cells and to reduce their overall reuse distances. The performance of DRP-WI is measured in terms of blocking probability and system capacity. Simulation results have confirmed the effectiveness of DRP-WI scheme. Under both uniform and non-uniform traffic distributions, DRP-WI exhibits outstanding performance in improving the system capacity. It can provide about 100% capacity improvement as compared to conventional fixed channel assignment scheme with 70 system channels.

• Archives of Pharmacal Research
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• 제28권1호
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• pp.1-15
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• 2005

Cancer is still a major global health concern even after an everlasting strive in conquering this dread disease. Emphasis is now given to chemoprevention to reduce the risk of cancer and also to improve the quality of life among cancer afflicted individuals. Recent progress in molecular biology of cancer has identified key components of the cellular signaling network, whose functional abnormality results in undesired alterations in cellular homeostasis, creating a cellular microenvironment that favors premalignant and malignant transformation. Multiple lines of evidence suggest an elevated expression of cyclooxygenase-2 (COX-2) is causally linked to cancer. In response to oxidative/pro-inflammatory stimuli, turning on unusual signaling arrays mediated through diverse classes of kinases and transcription factors results in aberrant expression of COX-2. Population-based as well as laboratory studies have explored a broad spectrum of chemopreventive agents including selective COX-2 inhibitors and a wide variety of anti-inflammatory phytochemicals, which have been shown to target cellular signaling molecules as underlying mechanisms of chemoprevention. Thus, unraveling signaling pathways regulating aberrant COX-2 expression and targeted blocking of one or more components of those signal cascades may be exploited in searching chemopreventive agents in the future.

• 한국정보통신학회논문지
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• 제6권6호
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• pp.819-826
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• 2002

셀룰러 뉴럴 네트워크는 국부적 연결특성을 가지고 있어 실시간 이미지처리에 적합한 뉴럴 네크워크이다. 또한 국부적 연결특징은 VLSI구현에 적합하다. 그의 응용분야는 패턴인식과 숫자인식 및 영상처리에 응용되고 있다. 본 논문에서, CNN은 전처리 단계로서 숫자의 특징점 추출에 이용된다. CNN을 이용한 그림자검출은 4내지 6방향으로 검출하여 숫자의 특징점을 방향별로 추출한다. 분류단계에서 이러한 형상자료는 다층BP뉴럴 네트워크의 입력벡터에 적합하도록 압축되어 입력된다. 실험결과 CNN을 통한 숫자인식은 굴림체의 경우96%이상의 인식율을 보여 만족할 만한 결과를 얻었다.

• Journal of Communications and Networks
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• 제7권2호
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• pp.192-206
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• 2005

Integration of mobile networks and Internet has started with 2.5 generation of mobile cellular networks. Internet traffic is today dominant traffic type worldwide. The hanger for higher data rates needed for data traffic and new IP based services is essential in the development of future wireless networks. In such situation, even 3G with up to 2 Mbit/s has not provided data rates that are used by Internet users with fixed broadband dial-up or through wired local area networks. The solution to provide higher bit rates in wireless access network has been found in wireless LAN although initially it has been developed to extend wired LAN into wireless domain. In this paper, we propose and describe a solution created for interoperability between mobile cellular network and WLAN. The integration between two networks, cellular and WLAN, is performed on the authentication, authorization, and accounting, i.e., AAA side. For that purpose we developed WLAN access controller and WLAN AAA gateway, which provide gateway-type access control as well as charging and billing functionalities for the WLAN service. In the development process of these elements, we have considered current development stadium of all needed network entities and protocols. The provided solution provides cost-effective and easy-to-deploy PLMN-WLAN Internetworking scenario.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권9호
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• pp.2098-2117
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• 2012

This paper jointly investigates the bandwidth allocation, transmission strategy and relay positions for two-way transmission aware cellular networks with network coding (NC). Our goal is to minimize the transmission power of mobile terminals (MTs). Consider a cellular system, where multiple MTs exchange information with their common base station, firstly, we propose an efficient bandwidth allocation method and then give a transmission strategy for each MT to determine whether to use relay stations (RSs) for its two-way transmission with the BS or not. To further improve the system performance, the optimal positions of RSs are also jointly discussed. A GA-based algorithm is presented to obtain the optimum positions for RSs. Besides, the impacts of frequency reuse on MT's transmission power and system spectral efficiency (SE) under different number of relays are also discussed in our work. Numerical results show that the proposed NC aware scheme can extend MTs' battery life at least 6% more than traditional method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권5호
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• pp.2243-2257
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• 2019

A heterogeneous cellular network (HCN) is useful to increase the spectral and energy efficiency of wireless networks and to reduce the traffic load from the macro cell. The performance of the secondary user equipment (SUE) is affected by interference from the eNodeB (eNB) in a macro cell. To decrease the interference between the macro cell and the small cell, allocating resources properly is essential to an HCN. This study considers the scenario of a software-defined heterogeneous cellular network and performs the resource allocation process. First, we show the system model of HCN and formulate the optimization problem. The optimization problem is a complex process including power and frequency resource allocation, which imposes an extremely high complexity to the HCN. Therefore, a hierarchical resource allocation scheme is proposed, which including subchannel selection and a particle swarm optimization (PSO)-based power allocation algorithm. Simulation results show that the proposed hierarchical scheme is effective in improving the system capacity and energy efficiency.

• IMMUNE NETWORK
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• 제9권1호
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• pp.1-3
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• 2009