• ETRI Journal
• /
• v.25 no.6
• /
• pp.475-488
• /
• 2003

In this paper, we propose an efficient and simple fair queuing algorithm, called new starting potential fair queuing (NSPFQ), which has O(1) complexity for virtual time computation and also has good delay and fairness properties. NSPFQ introduces a simpler virtual time recalibration method as it follows a rate-proportional property. The NSPFQ algorithm recalibrates the system virtual time to the minimum virtual start time among all possible virtual start times for head-of-line packets in backlogged sessions. Through analysis and simulation, we show that the proposed algorithm has good delay and fairness properties. We also propose a hardware implementation framework for the scheduling algorithm.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.11S
• /
• pp.3269-3277
• /
• 1999

To promote the inclusion of end-to-end congestion control in the design of future protocols using best-effort traffic, we propose a router mechanism, Extended FRED(ex-FRED). In this paper, we catagorize the TCP controlled traffics into robust and fragile traffic and discuss several unfairness conditions between them caused by the diverse applications. For example, fragile traffic from bursty application cannot use its fair share due to their slow adaptation. Ex-FRED modifies the FRED(Fair Random Early Drop), which can show wrong information due to the narrow view of actual buffer. Therefore, Ex-FRED uses per-flow accounting in larger virtual buffer to impose an each flow a loss rate that depends on the virtual buffer use of a flow. The simulation results show that Ex-FRED uses fair share and has good throughput.

• Culinary science and hospitality research
• /
• v.14 no.2
• /
• pp.225-236
• /
• 2008

This study is to explore how the employees of tourist hotels perceive moderate room rates and price acceptance. Sampling was taken among employees for deluxe hotels at Yusong in Daejeon. A total of 150 samples were distributed and 124 valid samples were selected for this research. Answers were processed by SPSS 15.0 after data coding. The results of study are as follows; First, annual average sales price of hotel rooms is \99,223, and the rack rates take up 49.7% of the transaction rates. Second, the rack rates which many employees think moderate are in the range of $50.09{\sim}75.13%(\100,000{\sim}150,000)$ of the rack rates. Third, many employees consider $40.07{\sim}50.09%(\80,000{\sim}100,000)$ of the rack rates as the moderate acceptability rates. Finally, the differences of fair rates by age and annual income were noticeable. These hotels ought to narrow the gap between rack rates and transaction rates. This study has a meaning to draw up a new plan for the room rate policy.

• Korean Journal of Health Education and Promotion
• /
• v.32 no.2
• /
• pp.75-84
• /
• 2015

Objectives: This study examines that the compatibilities between the health promotion programs in community health center and the leading health indicators in National Health Plan. Methods: We analyzed health promotion programs associated with three health indicators; smoking(smoking rate in male), alcohol use(alcohol use rate in adults), obesity(obesity rate) in twenty five community health centers in Seoul. First, we classified three groups(excellent, fair and poor groups) using average scores of Seoul, that of Korea and National Health Plan2010 goals in three health indicators. Afterwards, we examined the compatibility between contents of health promotion programs regarding leading health indicators and the specific program activities. Results: The compatibility levels between health indicators and contents of health promotion programs was 80 % for smoking among fair and poor groups while fair and poor for smoking reported 60% and 70%, respectively. For obesity, excellent group reported 80% and fair group had 91%. Conclusion: In conclusion, although all districts were able to access available data for health indicators and health statistics every year, it seems that they did not only utilize these data enough in conjunction with health promotion programs but also did not integrate specific activities according to National Health Plan systematically.

• Journal of Institute of Control, Robotics and Systems
• /
• v.6 no.8
• /
• pp.638-651
• /
• 2000

When the bandwidth resources in a packet-switched network are shared among sessions by MAX-MIN flow control each session is required to transmit its data into the network subject to the MAX-MIN fair rate which is solely determined by network loadings. This passive behavior of sessions if fact can cause seri-ous QoS(Quality of Service) degradation particularly for real-time multimedia sessions such as video since the rate allocated by the network can mismatch with what is demanded by each session for its QoS. In order to alleviate this problem we extend the concept of MAX-MIN fair bandwidth allocations as follows: Individual bandwidth demands are guaranteed if the network can accommodate them and only the residual network band-width is shared in the MAX-MIN fair sense. On the other hand if sum of the individual bandwidth demands exceeds the network capacity the shortage of the bandwidth is shared by all the sessions by reducing each bandwidth guarantee by the MAX-MIN fair division of the shortage. we present a novel flow control algorithm to achieve this extended MAX-MIN fairness and show that this algorithm can be implemented by the existing ATM ABR service protocol with minor changes. We not only analyze the steady state asymptotic stability and convergence rate of the algorithm by appealing to control theories but also verify its practical performance through simulations in a variety of network scenarios.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37 no.6B
• /
• pp.405-413
• /
• 2012

WFQ(Weighted Fair Queuing) is the most popular fair queuing algorithm to guarantee the Quality-of-Service(QoS), but it has the inherent drawback of a poor resource utilization, particularly under the low rate traffic requiring a tight delay bound. It was recently identified that the poor utilization is mainly due to non-optimized latency of a traffic flow and then LOFQ(Latency-Optimized Fair Queuing) to overcome the drawback was introduced. The LOFQ algorithm, however, renews their optimal latencies for all flows whenever a new flow arrives, which results in the high implementation complexity of O($N^2$).This paper is to reduce thecomplexity to O(1). The proposed method is first to derive the optimal latency index function from the statistical QoS characteristics of the offered load, and then to simply calculate the optimal latency index of the arriving flow using the function.

• The Journal of the Korea Contents Association
• /
• v.5 no.5
• /
• pp.248-254
• /
• 2005

The existing buffer management scheme is caused by with burstness characteristic of the TCP traffic and with only the transmission which is not loss it provides the smallest transmission rate guarantee where the GFR demands and a fair characteristic. In order to provide a high fair characteristic from the dissertation which it sees with the smallest transmission rate guarantee where the GFR demands it proposed the existing buffer algorithm which applies a Fuzzy mechanism in the existing buffer management technique. The proposed algorithm decides a packet disuse used by three parameters which are composed of tagging information, the buffer usage, and the load of VC. Simulation results shows that the fairness and goodput of the proposed algorithm were excellent where the size of MCR will become larger, from the switch the Double-EPD or the DFBA was visible a similar efficiency even from size change of the buffer. The algorithm which is proposed provides a good throughput and a fair characteristic.

• The KIPS Transactions:PartC
• /
• v.13C no.3 s.106
• /
• pp.331-338
• /
• 2006

Most fair packet schedulers supporting quality-of-services of real-time multimedia applications are based on the finish time design scheme in which the expected transmission finish time of each packet is used as its timestamp. This scheme can adjust the latency of a flow with raising the flow's scheduling rate but it may suffer from severe bandwidth loss due to the coupled rate and delay allocation. This paper first introduces the concept of delay resource, and then proposes a scheduling method to improve the bandwidth utilization in which delay resource being lost due to the coupled allocation is transformed into bandwidth one. The performance evaluation shows that the proposed method gives higher bandwidth utilization by up to 50%.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.4A
• /
• pp.332-340
• /
• 2010

In this paper, we deal with multi-user diversity scheduling methods that transmit simultaneously signals from multiple users using superposition coding multiplexing. These methods can make various scheduling methods be obtained, according to strategies for user selection priority from the first user to the first-following users, strategies for per-user power allocation, and resulting combining strategies. For the first user selection, we consider three strategies such as 1) higher priority for a user with a better channel state, 2) following the proportional fair scheduling (PFS) priority, 3) higher priority for a user with a lower average serving rate. For selection of the first-following users, we consider the identical strategies for the first user selection. However, in the second strategy, we can decide user priorities according to the original PFS ordering, or only once an additional user for power allocation according to the PFS criterion by considering a residual power and inter-user interference. In the strategies for power allocation, we consider two strategies as follows. In the first strategy, it allocates a power to provide a permissible per-user maximum rate. In the second strategy, it allocates a power to provide a required per-user minimum rate, and then it reallocates the residual power to respective users with a rate greater than the required minimum and less than the permissible maximum. We consider three directions for scheduling such as maximizing the sum rate, maximizing the fairness, and maximizing the sum rate while maintaining the PFS fairness. We select the max CIR, max-min fair, and PF scheduling methods as their corresponding reference methods [1 and references therein], and then we choose candidate scheduling methods which performances are similar to or better than those of the corresponding reference methods in terms of the sum rate or the fairness while being better than their corresponding performances in terms of the alternative metric (fairness or sum rate). Through computer simulations, we evaluate the sum rate and Jain’s fairness index (JFI) performances of various scheduling methods according to the number of users.

• Computers and Concrete
• /
• v.8 no.2
• /
• pp.177-192
• /
• 2011

This research paper aims at computer based modeling of carbonation induced corrosion under extreme conditions and its experimental verification by incorporating enhanced electrochemical and mass balance equations based on thermo-hygro physics with strong coupling of mass transport and equilibrium in micro-pore structure of carbonated concrete for which the previous research data is limited. In this paper the carbonation induced electrochemical corrosion model is developed and coupled with carbon dioxide transport computational model by the use of a concrete durability computer based model DuCOM developed by our research group at concrete laboratory in the University of Tokyo and its reliability is checked in the light of experiment results of carbonation induced corrosion mass loss obtained in this research. The comparison of model analysis and experiment results shows a fair agreement. The carbonation induced corrosion model computation reasonably predicts the quantitative behavior of corrosion rate for normal air dry relative humidity conditions. The computational model developed also shows fair qualitative corrosion rate simulation and analysis for various pH levels and coupled environmental actions of chloride and carbonation. Detailed verification of the model for the quantitative carbonation induced corrosion rate computation under varying relative conditions, different pH levels and combined effects of carbonation and chloride attack remain as scope for future research.