• Interdisciplinary Bio Central
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• 제3권2호
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• pp.8.1-8.6
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• 2011

Background: Thanks to the development of the mathematical/statistical reverse engineering and the high-throughput measuring biotechnology, lots of biologically meaningful genegene interaction networks have been revealed. Steady-state analysis of these systems provides an important clue to understand and to predict the systematic behaviours of the biological system. However, modeling such a complex and large-scale system is one of the challenging difficulties in systems biology. Results: We introduce a new stochastic modeling approach that can describe gene regulatory mechanisms by dividing two (DNA and protein) layers. Simple queuing system is employed to explain the DNA layer and the protein layer is modeled using G-networks which enable us to account for the post-translational protein interactions. Our method is applied to a transcription repression system and an active protein degradation system. The steady-state results suggest that the active protein degradation system is more sensitive but the transcription repression system might be more reliable than the transcription repression system. Conclusions: Our two layer stochastic model successfully describes the long-run behaviour of gene regulatory networks which consist of various mRNA/protein processes. The analytic solution of the G-networks enables us to extend our model to a large-scale system. A more reliable modeling approach could be achieved by cooperating with a real experimental study in synthetic biology.

• 대한전자공학회논문지TC
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• 제42권12호
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• pp.95-102
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• 2005

이 논문은 IEEE802.11a/b/g 무선 랜(Wireless LAN) 억세스 포인트(Access Point)의 성능 향상을 목적으로 한다. 하나의 서버, 멀티 Queue이론, FIFS시스템 모델을 이용하여 우선순위를 적용한 다중 버퍼에 변경된 패킷 구조를 적용하고, MAC에 QoS를 적용한 다중 버퍼를 두고 우선순위가 할당된 데이터에 헤더를 붙여 각각 할당된 다중 버퍼로 전송하여 부하시 생기는 전송지연을 해결하여 전송 효율을 높이고 억세스 포인트의 성능을 향상시키는데 있다. 우리는 여기서 일정 모델의 억세스 포인트와 버퍼 사용에 대한 파라메타를 이용한다. IP 패킷 페이로드의 함수로 패킷의 평균 서비스 타임을 분석하여 파라메타에 적용한다. 버퍼에서 패킷 손실이 생기기 전까지의 수를 계산하여 알고리듬에 구현하고 디자인 한다.

• 한국도로학회논문집
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• 제16권1호
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• pp.111-118
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• 2014

PURPOSES : This study performs fundamental research on ramp-metering design criteria. METHODS : We carefully review previous studies in terms of ramp-metering design criteria and then consider applicability in Korea. For this, traffic simulation model is employed to analyze actual effect according to specific location of stop-line when implementing ramp-metering. RESULTS : When a stop-line moving forward with a 50m interval, travel speed at mainline relative to current stop-line location tends to decrease. However, traveling speed at approach roads increase about 5~18% under the same condition. When a stop-line location moving backward with a 50m interval, mainline travel speed increase approximately 17~32% whereas traveling speed at approach roads decrease. All cases are compared with the current stop-line location. CONCLUSIONS : We believe that both cases are useful with respect to freeway management. For example, moving forward a stop-line case can be used management for queuing area at ramp section and approach roads. Moving backward a stop-line case can be used for traffic control, focusing on mainline of freeways.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권10호
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• pp.4724-4747
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• 2016

To efficiently reduce on-grid energy consumption, the admission control algorithm in the hybrid energy powered cellular network (HybE-Net) with base stations (BSs) powered by on-grid energy and solar energy is studied. In HybE-Net, the fluctuation of solar energy harvesting and energy consumption may result in the imbalance of solar energy utilization among BSs, i.e., some BSs may be surplus in solar energy, while others may maintain operation with on-grid energy supply. Obviously, it makes solar energy not completely useable, and on-grid energy cannot be reduced at capacity. Thus, how to control user admission to improve solar energy utilization and to reduce on-grid energy consumption is a great challenge. Motivated by this, we first model the energy flow behavior by using stochastic queue model, and dynamic energy characteristics are analyzed mathematically. Then, fuzzy logic based admission control algorithm is proposed, which comprehensively considers admission judgment parameters, e.g., transmission rate, bandwidth, energy state of BSs. Moreover, the index of solar energy utilization balancing is proposed to improve the balance of energy utilization among different BSs in the proposed algorithm. Finally, simulation results demonstrate that the proposed algorithm performs excellently in improving solar energy utilization and reducing on-grid energy consumption of the HybE-Net.

• 한국BIM학회 논문집
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• 제11권3호
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• pp.1-11
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• 2021

BIM is one of the means of reducing the economic loss caused by design errors. These features of BIM have led to increased use of BIM. With the increasing use of BIM, several studies have been conducted to analyze the performance of BIM. As the importance of BIM staff is emphasized in the performance analysis of BIM, the human resource allocation of BIM staff can become an important research issue. However, there are few studies to measure the workforce effectiveness of BIM staff. Ham et al (2020) measured BIM workforce efficiency using FCFS queue model rules. Since design errors can have different effects on the project depending on the type, there are design errors that must be dealt with first. Therefore, in this study, a priority queue was used to solve design errors with high priority first. The performance of BIM-based design verification was analyzed by quantitatively analyzing the performance of BIM staff when the priority rule was applied to the design error processing sequence.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권2호
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• pp.683-701
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• 2012

IEEE 802.11 standard has achieved huge success in the past decade and is still under development to provide higher physical data rate and better quality of service (QoS). An important problem for the development and optimization of IEEE 802.11 networks is the modeling of the MAC layer channel access protocol. Although there are already many theoretic analysis for the 802.11 MAC protocol in the literature, most of the models focus on the saturated traffic and assume infinite buffer at the MAC layer. In this paper we develop a unified analytical model for IEEE 802.11 MAC protocol in ad hoc networks. The impacts of channel access parameters, traffic rate and buffer size at the MAC layer are modeled with the assistance of a generalized Markov chain and an M/G/1/K queue model. The performance of throughput, packet delivery delay and dropping probability can be achieved. Extensive simulations show the analytical model is highly accurate. From the analytical model it is shown that for practical buffer configuration (e.g. buffer size larger than one), we can maximize the total throughput and reduce the packet blocking probability (due to limited buffer size) and the average queuing delay to zero by effectively controlling the offered load. The average MAC layer service delay as well as its standard deviation, is also much lower than that in saturated conditions and has an upper bound. It is also observed that the optimal load is very close to the maximum achievable throughput regardless of the number of stations or buffer size. Moreover, the model is scalable for performance analysis of 802.11e in unsaturated conditions and 802.11 ad hoc networks with heterogenous traffic flows.

• 대한전자공학회논문지SD
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• 제45권12호
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• pp.73-82
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• 2008

슈퍼스칼라 프로세서에서 리오더 버퍼의 복잡도를 줄이는 여러 가지 방법이 제시되었다. 그 중에서 리오더 버퍼의 포트를 가장 단순하게 하는 방법은 하나로 되어 있는 리오더 버퍼의 구조를 실행 유닛의 개수만큼 여러 개로 나누어 분산된 리오더 버퍼로 구현하는 것이다. 각각의 분산된 리오더 버퍼는 실행 유닛의 작업 부하에 따라 그 크기를 달리 할 수 있다. 하지만 분산된 리오더 버퍼의 크기에 따라 성능의 변화가 크다. 지금까지의 분산된 리오더 버퍼로 나누는 연구는 적절한 크기를 결정하기 위해 시뮬레이션 결과에 기반 하여 직관적으로 유추하였다. 본 논문은 분산된 리오더 버퍼에 M/M/1 큐잉 이론을 이용한 수학적모델을 적용하여 최적의 크기를 결정하고 CPU2000 벤치마크 프로그램을 수행하여 성능을 측정하고 평가하였으며 기존 슈퍼스칼라 프로세서 성능의 99.2%를 보여주는 분산된 리오더 버퍼의 최적 크기를 정할 수 있었다. 기존의 리오더 버퍼와 본 논문에서 제시한 분산된 리오더 버퍼를 HDL로 구현하였을 때 포트에서 82%의 하드웨어 자원과 30%이상의 지연시간을 줄였다.

• 한국경영과학회지
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• 제37권4호
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• pp.73-93
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• 2012

In recent years, service delivery systems employing a self-service approach have been rapidly spreading. Since a self-service system provides a lower product price, it attracts more customers. However, some system managers are still hesitant to accept a self-service system, because there is no systematic model to predict its performance. Therefore, this research attempts to provide a systematic and quantitative model to predict the performance of a self-service system, focused specifically on a self-service gas station. Under this model, the traditional queuing theory was adopted to describe the general self-service process, but it is also assumed that some changes occur in both the customer arrival rate and the service performance rate. In particular, the price elasticity was introduced to capture the change in the customer arrival rate, and the existence of learning effect and helpers were assumed to design the changed service performance rate. Under these assumptions, a simulation model for a self-service gas station is established, and three performance measurements, such as average number of customers, average waiting time, and Utilization are observed, depending on the changes in price difference and helper-operating time. In this research, the optimal operation strategy for price differentiation and helper-operating time is proposed in accordance with the level of the customer learning rate. Although this research confines the scope of the study to the self-service gas station model, the results of this research can be applied to any type of self-service system.

• 대한전자공학회논문지TC
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• 제40권12호
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• pp.9-17
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• 2003

본고는 차세대 IP망(NGN)에서의 대역 설계 방법에 관한 것이다. 특히, VoIP 뿐만 아니라 데이터 서비스를 수용하는 에지 라우터에서의 호레벨 및 패킷 레벨 음성 트래픽 대역 설계 방법을 제시하였다. 호레벨 모델은 실제 연결되는 호의 수를 통계적으로 계산하기 위해 평균, 분산과 같은 통계적 기법을 사용하고, 패킷레벨 모델은 M/G/1 큐잉 모델을 활용하여 음성 및 데이터 트래픽의 부하를 나타내었다. 제시된 트래픽 모델을 통해서 계산된, 음성과 데이터 연결을 위한 대역폭을 기반으로 최대 트래픽 부하를 예측할 수 있고, 또한 수치 시험을 통한 이의 결과를 제시하였다.

• 한국컴퓨터정보학회논문지
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• 제17권12호
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• pp.121-129
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• 2012

본 논문에서는 IEEE 802.15.4에서 저속 데이터 전송률을 요구하는 응용을 운용하기 위한 WBAN 시스템 모델을 제안한다. 의료용 응용서비스는 상이한 데이터 전송률과 응급 메시지 전송을 요구하기 때문에 기존의 무선 센서 네트워크 기술을 참조할 수 없다. 이러한 기존 시스템의 문제점들을 해결하기 위하여 WBAN에 적합한 시스템 모델과 WBAN MAC 프로토콜에 관한 내용을 제안하였다. 첫째, 경쟁 구간에 우선순위 큐잉을 적용하여 MAC 명령어 프레임의 전송을 보장할 수 있는 시스템 모델을 제안하였다. 둘째, 제안한 시스템 모델을 사용하기 위해 MAC 프레임을 새롭게 정의하였다. 셋째, 경쟁구간에서 우선순위가 없는 데이터 프레임의 처리량 및 전송 성공 확률을 향상시킬 수 있는 데이터 전송률을 고려한 WBAN CSMA/CA 백오프 알고리즘을 제안하였다. 제안한 WBAN CSMA/CA 백오프 알고리즘은 BAN(Body Area Network) 및 WSN(Wireless Sensor Network)의 시뮬레이션이 가능한 OMNeT++의 Castalia를 이용하여 구현하였다. 시뮬레이션 결과 제안한 시스템 모델이 기존 방식과 비교하여 데이터 처리량이 개선되고, 충돌 확률이 감소함을 확인할 수 있었다.