• Journal of Communications and Networks
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• 제16권2호
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• pp.121-129
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• 2014

The trend of an increasing demand for a high-quality user experience, coupled with a shortage of radio resources, has necessitated more advanced wireless techniques to cooperatively achieve the required quality-of-experience enhancement. In this study, we investigate the critical problem of rate splitting in heterogeneous cellular networks, where concurrent transmission, for instance, the coordinated multipoint transmission and reception of LTE-A systems, shows promise for improvement of network-wide capacity and the user experience. Unlike most current studies, which only deal with spectral efficiency enhancement, we implement an optimal rate splitting strategy to improve both spectral efficiency and energy efficiency by exploring and exploiting cooperation diversity. First, we introduce the motivation for our proposed algorithm, and then employ the typical cooperative bargaining game to formulate the problem. Next, we derive the best response function by analyzing the dual problem of the defined primal problem. The existence and uniqueness of the proposed cooperative bargaining equilibrium are proved, and more importantly, a distributed algorithm is designed to approach the optimal unique solution under mild conditions. Finally, numerical results show a performance improvement for our proposed distributed cooperative rate splitting algorithm.

• 약학회지
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• 제55권1호
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• pp.49-55
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• 2011

Tumor necrosis factor-related apoptosis inducing ligand (TRAIL) is one of the promising anti-cancer agent because of its ability to selectively induce apoptosis in tumor cell lines but not in normal cells. However, TRAIL resistance has been reported in some cancer cells including hepatocarcinoma cells. Therefore, studies of agents that sensitize TRAIL-resistant cancer cells could be a effective therapeutic approach in cancer management. In our study, we examined the effect of combination of TRAIL with apigenin in human hepatocellular carcinoma cells. As a result, the combined use of TRAIL and apigenin significantly enhanced the cytotoxicity in PLC-PRF5 cells. Flow cytometry analysis after annexin V-FITC/PI dual staining showed that this increase of cell cytotoxicity was related to enhanced apoptosis in combined treatment of TRAIL with apigenin. Furthermore, synergistic induction of apoptosis was also confirmed by observation of morphological changes and annexin V-FITC/PI fluorescence. Our findings suggests that apigenin has the potential to improve the efficiency of TRAIL-based therapies in human hepatocellular carcinoma cells. Further study is needed to reveal the molecular mechanisms of this combined therapy.

• 국제초고층학회논문집
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• 제6권1호
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• pp.49-72
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• 2017

The Guangzhou International Finance Centre (IFC) is a landmark building that symbolizes the emerging international strength of Guangzhou, China's third largest city. It is also one of the dual iconic towers along the main axis of Guangzhou Zhujiang New Town. Arup adopted a total engineering approach in embracing sustainability and aiming at high efficiency solutions based on performance-based design principles covering structures, building services, fire engineering, vertical transportation, and façade performance to constitute an efficient and cost-effective overall building design. Through dynamic integration of architectural and engineering principles, Guangzhou IFC represents a pioneering supertall building in China. It adopts a diagrid exoskeleton structural form that is clearly expressed through the building's façade and gives the building its distinctive character. The aerodynamic shape of the building not only presents the aesthetic quality of elegant simplicity, but also reduces the effects of wind, thereby reducing the size and weight of the structure. State-of-the-art advanced engineering methods, such as optimization techniques and nonlinear finite element modelling, were applied in parallel with large-scale experimental programs to achieve an efficient and high-performance design taking into account the constructability and cost-effectiveness for a project of this scale.

• 한국정보통신학회논문지
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• 제8권7호
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• pp.1553-1557
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• 2004

임베디드 하드웨어 유전자 알고리즘을 위한 실시간 처리 시스템을 설계하였다. 제안된 시스템은 유전자 알고리즘의 기본 모듈인 selection, crossover, 및 mutation과 evaluation을 병행적으로 동작시키기 위해서 이중 프로세서로 구현하였다. 구현된 시스템은 두개의 Xscale 프로세서와 진화 하드웨어가 내장된 FPGA 로 구성되었다. 또한 본 시스템은 유전자 알고리즘의 기본 모듈 수행이 두 개의 프로세서에 자동으로 균등 배분되는 구조를 지니고 있어, 유전자 알고리즘 처리의 효율성을 극대화 할 수 있다. 제안된 임베디드 하드웨어 유전자 알고리즘 처리 시스템은 임베디드 리눅스 운영체제에서 수행되며 진화 하드웨어에서 실시간으로 처리된다. 또한 제안된 이중 프로세서의 각 프로세서 모듈은 동일한 구조로 가지고 있으므로 여러 개의 모듈을 직렬 연결하여 빠른 하드웨어 유전자 알고리즘 실시간 처리에 그대로 사용될 수 있다.

• Journal of Power Electronics
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• 제14권5호
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• pp.815-826
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• 2014

An improved bridgeless interleaved boost power factor correction (PFC) rectifier to improve power efficiency and component utilization is proposed in this study. With combined conventional bridgeless PFC circuit and interleaved technology, the proposed rectifier consists of two interleaved and magnetic inter-coupling boost bridgeless converter cells. Each cell operates alternatively in the critical conduction mode, which can achieve the soft-switching characteristics of the switches and increase power capacity. Auxiliary blocking diodes are employed to eliminate undesired circulating loops and reduce current-sensing noise, which are among the serious drawbacks of a dual-boost PFC rectifier. Magnetic component utilization is improved by symmetrically coupling two inductors on a unique core, which can achieve independence from each other based on the auxiliary diodes. Through the interleaved approach, each switch can operate in the whole line cycle. A simple control scheme is employed in the circuit by using a conventional interleaved controller. The operation principle and theoretical analysis of the converter are presented. A 600 W experimental prototype is built to verify the theoretical analysis and feasibility of the proposed rectifier. System efficiency reaches 97.3% with low total harmonic distortion at full load.

• Journal of Communications and Networks
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• 제13권4호
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• pp.408-417
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• 2011

The stringent performance requirement for the high efficiency of routing protocols on the Internet can be satisfied by exploiting the threaded border gateway protocol (TBGP) on multi-cores, but the state-of-the-art TBGP performance is restricted by a mass of contentions when racing to access the routing table. To this end, the highly-efficient parallel access approach appears to be a promising solution to achieve ultra-high route processing speed. This study proposes a general routing table structure consisting of two-level tries for fast parallel access, and it presents a heuristic-based divide-and-recombine algorithm to solve a mass of contentions, thereby accelerating the parallel route updates of multi-threading and boosting the TBGP performance. As a projected TBGP, this study also modifies the table operations such as insert and lookup, and validates their correctness according to the behaviors of the traditional routing table. Our evaluations on a dual quad-core Xeon server show that the parallel access contentions decrease sharply by 92.5% versus the traditional routing table, and the maximal update time of a thread is reduced by 56.8 % on average with little overhead. The convergence time of update messages are improved by 49.7%.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1136-1139
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• 2000

The paper describes a new and rigorous mathematical model for the rotor field oriented system with induction motor which uses the estimated speed and rotor flux based on a Model Reference Adaptive System, as well as the real-time approach. The estimated speed and rotor flux is used for the speed and flux feedback control. The stability and the convergence of the estimator are improved on the basis of hyperstability theory for non-linear systems. The real-time controller and estimator are implemented with a sampling period of $926{\mu}s$ using a dual TMS320C44 floating-point digital signal processor. The validity of the proposed method is verified by simulation, and also, the sensorless control was tested on the propulsion system simulator, used for the development of Korean High-Speed Railway Train (KHSRT) [5].

• ETRI Journal
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• 제33권4호
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• pp.487-496
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• 2011

Korea Multi-Purpose Satellite-5 (KOMPSAT-5) is the first satellite in Korea that provides 1 m resolution synthetic aperture radar (SAR) images. Precise orbit determination (POD) using a dual-frequency IGOR receiver data is performed to conduct high-resolution SAR images. We suggest orbit determination strategies based on a differential GPS technique. Double-differenced phase observations are sampled every 30 seconds. A dynamic model approach using an estimation of general empirical acceleration every 6 minutes through a batch least-squares estimator is applied. The orbit accuracy is validated using real data from GRACE and KOMPSAT-2 as well as simulated KOMPSAT-5 data. The POD results using GRACE satellite are adjusted through satellite laser ranging data and compared with publicly available reference orbit data. Operational orbit determination satisfies 5 m root sum square (RSS) in one sigma, and POD meets the orbit accuracy requirements of less than 20 cm and 0.003 cm/s RSS in position and velocity, respectively.

• 한국정보시스템학회지:정보시스템연구
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• 제15권4호
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• pp.125-147
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• 2006

Internet shopping mall has dual nature of information technology features defined by the web-based application system and marketing features explained by the shopping marketplaces. The purpose of this study aims at analyzing the consumer's attempt to purchase and re-purchase intention to the internet shopping mall to combine the IT perspective and the marketing perspective. This paper develop the integrated research model with the acceptance behaviors of customers through consumer's purchase decision process(pre-purchase stage and post-purchase stage). The results from an empirical survey as follows: First, the integrated model is valid in predicting the acceptance of the internet shopping malls by using structured equation modeling. Second, there are the differences between pre-purchase stage and post-purchase stage by each conceptual constructs. Finally, the results of MSEM(Multi-group Structured Equation Modeling) indicate the perceived ease of use and perceived trust to the attitude to the internet shopping mall is more effectively predicted at the pre-purchase stage. Vice versa, the perceived usefulness to the intention to the purchase intention of internet shopping mall is more effectively predicted at the post-purchase stage. This study provides an integrative approach to develop the effective and successful internet shopping mall strategy.

• 대한전자공학회논문지TC
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• 제41권9호
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• pp.39-45
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• 2004

순차적인 관찰값을 바탕으로 하고 신호검출에 소요되는 시간이 고정된 신호검출기의 제작에 관한 방법을 제안하며 이는 하드웨어의 복잡도를 감소시키는 장점이 있다. 제안된 방법은 Voronoi 다이어그램과 Delaunay 분할을 사용한다. 제안된 신호검출기 제작은 또한 고정 지연 트리 검색 검출 (FDTS) 방법에 기반을 둔다. FDTS 는 효율적인 순차적 신호검출 알고리즘이며 심볼간 간섭이 존재하는 채널에서 결정 궤환 등화기법 (DFE)과 결합하여 최적화에 근접한 성능을 보인다. 이러한 접근방법에서는 Voronoi 다이어그램 혹은 등가적으로 Delaunay 분할에 포함된 정보를 활용하여 다차원 유클리드 공간에서의 상대적인 관찰값의 위치를 계산하며 이러한 방법이 효율적인 계산을 유도하는 신호검출기의 제작에 이용된다.