• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권1호
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• pp.186-205
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• 2019

Intercell interference coordination (ICIC) is considered as a promising technique to increase the spectral efficiency of OFDMA cellular systems. The soft frequency reuse (SFR) and fractional frequency reuse (FFR) are representative and efficient management techniques for ICIC. Herein, to enhance the performance of the SFR scheme, we propose a call admission (CAC) scheme. In this CAC scheme, called Spectrum handoff-SFR(S-SFR), the spectrum handoff technique is applied to the user equipment (UE) located near the cell center. We derive the traffic analysis model to describe the S-SFR. In addition, a two-dimensional (2-D) Markov chain and an outage analysis are used in our analytical model. From the traffic analysis, the significant performance measures are the outage probability, call blocking probability, system throughput and resource utilization. Based on those, the outage probability and system throughput are obtained using resource utilization as an interference pattern. The analytical results are verified with computer simulation results. Finally, we compare our proposed scheme with other ICI schemes.

• Journal of Communications and Networks
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• 제15권5호
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• pp.469-475
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• 2013

In this paper, we propose an efficient interference management technique which controls the number of resource blocks (or subcarriers) shared with other cells based on statistical interference levels among cells. The proposed technique tries to maximize average throughput of a femto cell user under a constraint on non-real time control of a femto cell network while guaranteeing a target throughput value of a macro cell user. In our proposed scheme, femto cells opportunistically use resource blocks allocated to other cells if the required average user throughput is not attained with the primarily allocated resource blocks. The proposed method is similar to the underlay approach in cognitive radio systems, but resource block sharing among cells is statistically controlled. For the statistical control, a femto cell sever constructs a table storing average mutual interference among cells and periodically updates the table. This statistical approach fully satisfies the constraint of non-real time control for femto cell networks. Our simulation results show that the proposed scheme achieves higher average femto user throughput than conventional frequency reuse schemes for time varying number of users.

• 가족자원경영과 정책
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• 제7권2호
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• pp.81-97
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• 2003

The purpose of this study is to identify the impacts of the 5 day workweek system on the family resource management. This family resource may be divided into four spheres (family relationship, household economy, household labor, and leisure activity). Data were obtained from 182 husbands and 182 his wives. He is employed in a company which have fully introduced the 5 day workweek system. Descriptive Statistics(frequency and mean) was used for examining a demographic characteristics and a thought of the system, and t-test analysis for the difference by sex and before and after. According th the results of this study, first, after operation of the 5 day workweek system, the couple have more conversation with each other than before. Second, in reality, the income was not decreased beyond expectation. During the new holiday, the couple take out to go on a visit, to do their shopping, and to eat out. Third, the household labor time is different by sex. But the husbands is reported that they are participated more in hanging out the laundry, cleaning, and care for children than before. Forth, the family leisure activity of the husbands in comparison with individual activity and wives increased more than before.

• 전자공학회논문지
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• 제54권2호
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• pp.9-15
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• 2017

본 논문은 원활한 통신이 어려운 재난안전통신 환경에서 고출력 단말이 한정된 주파수 자원을 효율적으로 이용할 수 있는 자원할당 기법을 제안한다. 고출력 단말을 도입함에 따라 단말 당 전송률이 증가하고 서비스 영역이 커질 수 있지만 일반 단말과 동일한 주파수 자원을 재사용할 경우 간섭도 증가하여 재난지역 및 인접 지역 전체 시스템 성능 저하의 원인이 된다. 간섭에 의해 기존 셀룰러 시스템 성능에 영향을 미칠 수 있기 때문에 3GPP (3rd Generation Partnership Project)에서는 고출력 단말의 사용 가능 주파수 대역을 상향링크 788-798MHz, 하향링크 758-768MHz로 제한하고 있다. 이러한 제약조건 하에서 단말의 최저 성능 보장을 위한 자원할당 방식을 제안하고 제안한 자원할당 방식의 성능을 모의실험을 통해 검증한다.

• 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.

• 동아시아경상학회지
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• 제10권4호
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• pp.1-18
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• 2022

Purpose - Through the analysis and research of different characteristics and related mechanisms of live commerce anchors, this paper aimed to help live commerce anchors to strengthen their characteristic advantages, beautify the live broadcast environment, improve resource allocation and enhance business performance, so as to help live commerce anchors to achieve better high-quality development. Research design, data, and methodology - This study was conducted by sample survey method on 361 live commercial anchors who have experience in using major online shopping malls for more than one year. Data analysis methods were frequency analysis, confirmatory factor analysis, reliability analysis, correlation analysis, and structural equation model analysis. Result - Hypothesis 1 through Hypothesis 5 were all supported. The results of this study suggest that professionalism and mutual entertainment of live commercial anchors have a significant impact on business performance, survival strategy, resource allocation and environment selection. The resource allocation and environment selection of live commercial anchors play a mediating role in the professionalism and mutual entertainment of live commercial anchors on business performance and survival strategy. Conclusion -The results implied that the professionalism and inter entertainment of live commercial anchors have a positive impact on business performance and survival strategy. In the new situation, live commercial anchors should further improve their professionalism and mutual entertainment, so as to achieve better development.

• 한국통신학회논문지
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• 제31권2A호
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• pp.119-127
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• 2006

Part-I과 II를 포함하는 본 연구에서는 하향링크 직교 주파수분할 다중접속(OFDMA) 방식을 위한 실제적인 동적 채널할당 방법에 대해 논의한다. OFDMA 시스템은 채널의 상태정보 궤환을 위한 상향링크에서의 오버헤드를 줄이기 위해 부반송파들의 집합을 하나의 부채널로 정의하고 이를 채널의 상태정보 궤환, 사용자 다중화 및 전력/부호화율 할당의 단위로 사용하는데 본 논문(part-I)에서는 부채널의 일반화된 형태로 연속구조와 분산구조를 정의하고 이들 각 부채널구조의 통계적 특성을 살펴본다. 특히, 각 구조에 대해 부채널상에서의 신호대 잡음비(SNR) 분포를 라이스 분포로 모델링함으로써 각 부채널의 채널 상태를 채널이득의 순시 평균 및 분산의 1, 2차 모멘트로 나타내고 주어진 다중경로 채널 모델에 대해 이 두 파라미터 값의 확률 분포를 유도한다. 본 논문의 결과는 part-II에서 라이스 모델링에 기초한 일반화된 동적자원할당 알고리즘을 제시하고 성능분석을 수행하는데 사용된다.

• 전자공학회논문지
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• 제50권2호
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• pp.20-26
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• 2013

본 논문에서는 셀룰라시스템이 운용중인 Licensed 주파수 대역에서 M2M 단말간 직접통신을 공존운용하기 위한 PHY 프레임구조를 제안한다. 최근 들어 SmartGrid, Mobile Health, Smart Car를 포함한 M2M(Machine to Machine) 서비스 시장이 빠른 속도로 성장하고 있다. 이러한 M2M 서비스를 Licensed 주파수 대역 기반의 셀룰라시스템을 통해서 제공하는 경우 자원의 낭비를 초래할 수 있다. 일예로, 서로 인접하여 위치하는 시나리오에서는 M2M 단말간 직접통신을 하는 것이 자원 활용 측면에서 효율적이다. 본 논문에서는 기존 셀룰라 통신시스템의 PHY 프레임구조를 변경하지 않는 것을 중요한 요구사항으로 정한다. 이러한 하위호환성 요구사항을 만족시키면서, 기존 셀룰라시스템과 동일한 licensed 주파수 대역에서 공존운용이 가능한 M2M 단말간 직접통신시스템의 PHY 프레임구조를 제안한다. 따라서, 본 논문에서 제안하는 M2M 직접통신을 위한 프레임 구조는 기존 셀룰라시스템과의 호환성을 유지하면서, M2M 단말간 직접통신을 위한 추가적인 주파수 소요 없이 한정된 주파수 자원을 효율적으로 활용할 수 있는 방안이 되리라 예상된다.

• 한국가축번식학회지
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• 제26권4호
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• pp.385-394
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• 2002

This study was constructed the correlations of the embryonic developmental rates and the frequency of chromosome aberration using ear-skin-fibroblast cell in nuclear transfer (NT) derived embryos. Karyoplast-oocyte complexes were fused and activated simultaneously, then cultured for seven days to assess development. The developmental rates of NT and in vitro fertilization (IVF) embryos were 55.4% vs 63.5%, 31.7% vs 33% and 13.4% vs 16.8% in 2 cell, 8 cell and blastocyst, respectively. Firstly, the frequency of chromosome aberrations were evaluated using fluorescent in situ hybridization (FISH) technique with porcine chromosome 1 submetacentric specific probe. Chromosome aberration was detected at day 3 on the embryo culture, the percentages of chromosomal aneuploidy in NT and IVF embryos at 4-cell stage were 40%, 31.3%, respectively. Secondly, embryonic fragmentation was evaluated at 4-cell stage embryo. Frequency of embryonic fragmentations was in 51.3% of NT, 61.3% of IVF, 28.9% of parthenogenetic activation at 4-cell stage. The proportion of fragmentation in NT embryos was higher than activation embryos. This result indicates that chromosomal abnormalities and embryonic fragments are associated with low developmental rate in porcine NT embryo. It is also suggest that abnormal porcine embryos produced by NT related with lower implantation rate, increased abortion rate and production of abnormal fetuses.

• 한국통신학회논문지
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• 제30권10C호
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• pp.976-982
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• 2005

In this paper, a channel-adaptive beamforming method is proposed for OFDMA (Orthogonal Frequency Division Multilexing Access) systems with smart antenna, in which the size of a cluster is determined adaptively depending on the frequency selectivity of the channel. The proposed method consists of 4 steps: initial channel estimation, refinement of channel estimates, region-splitting, and computation of weight vector for each region. In the proposed method, the size of a cluster for resource unit is determined adaptively according to a region-splitting criterion. It is shown by simulation that the proposed method shows good performances in both frequency-flat and frequency-selective channels.