• The Journal of Asian Finance, Economics and Business
• /
• 제9권4호
• /
• pp.315-324
• /
• 2022

The goal of this study is to understand better the relationship between hospital bed occupancy rate and cost rigidity as a proxy for the degree of hospital bed congestion, as well as the relationship between the risk of changes in hospital bed occupancy rate and congestion cost, targeting public hospitals. As public hospitals for analysis, we selected hospital projects from the Public Enterprises Survey Reports published by the Department of Public Enterprises, Ministry of Finance, and obtained unbalanced panel data consisting of 1,505 hospitals and 15 years, totaling 12,595 hospitals and years. The analysis revealed that the risk of changes in the bed occupancy rate increases the degree of cost rigidity and leads to a decrease in the variable cost ratio; furthermore, an increase in the bed occupancy rate decreases the degree of cost rigidity and leads to an increase in the variable cost ratio. These findings suggest that although public hospitals are taking managerial actions to avoid congestion costs, congestion costs resulting from higher bed occupancy rates have not been eliminated. The regression analysis results show that even if congestion costs arise as the occupancy rate increases, they are covered by the increase in revenue associated with the increase in the occupancy rate.

• 대한토목학회논문집
• /
• 제26권1D호
• /
• pp.49-58
• /
• 2006

본 연구는 도시개발밀도와 교통시설용량 간의 영향관계를 실증적으로 분석하여, 교통성과(transportation performance)를 극대화하기 위한 토지이용방안을 모색하는 것이다. 이를 위해 서울시 도심을 사례분석지역으로 선정하여 다양한 개발밀도 시나리오에 따라 교통용량의 한계를 감안한 개발용량을 산정하였다. 개발밀도 변화에 따른 교통영향분석을 위한 분석모형으로 SECOMM모형이 제시되었고, 이를 활용하여 20개의 다양한 개발밀도 대안의 영향을 분석하였다. 분석 결과, 도심고밀개발시교통 관점에서 볼 때 분석상 교통적으로 가장 지속가능성이 높은 수준은 도심혼잡통행료를 징수하고 용적률을 460% 까지 개발했을 때인 것으로 나타났다. 한편 도심용적률이 460%를 상회해도 서울시 전체적인 교통상황이 지속적으로 개선되는 것으로 분석되어, 통행료 수준을 높임으로써 지속가능한 교통여건을 달성하는 것이 보다 바람직할 것으로 판단된다. 한편, 도심에서 혼잡통행료를 부과하지 않는다면 도심에서 최대 용적률 430%까지 밖에 고밀화를 진행할 수 없고 이때 서울시 전체적으로 개선폭도 그리 크지 않은 것으로 분석되었다. 따라서 도심고밀화를 위해서는 교통수요관리시책(TDM)과 병행하는 것이 필수적일 것으로 사료된다.

• 한국조경학회지
• /
• 제33권3호
• /
• pp.56-64
• /
• 2005

Despite there have been m?my studies about the relationships between congestions and satisfaction in outdoor recreation field, the results indicated only weak impacts of congestions on the satisfaction. This study thus aims to investigate the influence of waiting situation on the whole valuation and satisfaction of guests at theme parks using new variables such as 'goal attainment' and then to suggest implications for waiting management. This study shows meaningful theoretical implications. First, congestion influences the satisfaction more strongly when it prevents guests from achieving their plan. Second, management of waiting time is important and the can be controlled well. When guests have something interested during the waiting time, they were satisfied with the quality of waiting time and overall experience in the theme park.

• 디지털산업정보학회논문지
• /
• 제8권2호
• /
• pp.81-94
• /
• 2012

This paper suggests PARED algorithm, a modified RED algorithm, that actively reacts to dynamic changes in network to apply packet drop probability flexibly. The main idea of PARED algorithm is that it compares the target queue length to the average queue length which is the criterion of changes in packet drop probability and feeds the gap into packet drop probability. That is, when the difference between the average queue length and the target queue length is great, it reflects as much as the difference in packet drop probability, and reflects little when the difference is little. By doing so, packet drop probability could be actively controled and effectively dealt with in the network traffic situation. To evaluate the performance of the suggested algorithm, we conducted simulations by changing network traffic into a dynamic stat. At the experiments, the suggested algorithm was compared to the existing RED one and then to ARED one that provided the basic idea for this algorithm. The results proved that the suggested PARED algorithm is superior to the existing algorithms.

• 교통기술과정책
• /
• 제7권5호
• /
• pp.125-132
• /
• 2010

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
• /
• pp.37-40
• /
• 2000

Multi Protocol Label Switching (MPLS) is a high performance method for forwarding packets (frames) through a network. It enables routers at the edge of a network to apply simple labels to packets (frames). we use MPLS in the core network for internet. MPLS provide high speed switching and traffic engineering in MPLS domain but at the Label Edge Router(LER) there is frequently cell discarding via congestion and buffer management method. It is one of the most important reasons retransmission and congestion. In this paper we propose advanced LER scheme that provide less cell loss rate also efficient network infrastructure.

• Journal of Electrical Engineering and Technology
• /
• 제7권4호
• /
• pp.501-512
• /
• 2012

Social welfare maximization in a double-sided auction market is performed by implementing an aggregation-based particle swarm optimization (CAPSO) algorithm for optimal placement and sizing of one Static Synchronous Series Compensator (SSSC) device. Dallied simulation results (without/with line flow constraints and without/with SSSC) are generated to demonstrate the impact of SSSC on the congestion levels of the modified IEEE 14-bus test system. The proposed CAPSO algorithm employs conventional quadratic smooth and augmented quadratic nonsmooth generator cost curves with sine components to improve the accurate of the model by incorporating the valve loading effects. CAPSO also employs quadratic smooth consumer benefit functions. The proposed approach relies on particle swarm optimization to capture the near-optimal GenCos and DisCos, as well as the location and rating of SSSC while the Newton based load flow solution minimizes the mismatch equations. Simulation results of the proposed CAPSO algorithm are compared to solutions obtained by sequential quadratic programming (SQP) and a recently implemented Fuzzy based genetic algorithm (Fuzzy-GA). The main contributions are inclusion of customer benefit in the congestion management objective function, consideration of nonsmooth generator characteristics and the utilization of a coordinated aggregation-based PSO for locating/sizing of SSSC.

• 한국경영과학회지
• /
• 제34권4호
• /
• pp.123-138
• /
• 2009

This study examined the first- and second-best pricing by stable dynamics in congested transportation networks. Stable dynamics, suggested by Nesterov and de Palma (2003), is a new model which describes and provides a stable state of congestion in urban transportation networks. The first-best pricing in user equilibrium models introduces user-equilibrium in the system-equilibrium by tolling the difference between the marginal social cost and the marginal private cost on each link. Nevertheless, the second-best pricing, which levies the toll on some, but not all, links, is relevant from the practical point of view. In comparison with the user equilibrium model, the stable dynamic model provides a solution equivalent to system-equilibrium if it is focused on link flows. Therefore the toll interval on each link, which keeps up the system-equilibrium, is more meaningful than the first-best pricing. In addition, the second-best pricing in stable dynamic models is the same as the first-best pricing since the toll interval is separately given by each link. As an effect of congestion pricing in stable dynamic models, we can remove the inefficiency of the network with inefficient Braess links by levying a toll on the Braess link. We present a numerical example applied to the network with 6 nodes and 9 links, including 2 Braess links.

• 한국멀티미디어학회논문지
• /
• 제3권4호
• /
• pp.399-406
• /
• 2000

다자간 화상회의에서 발생하는 네트워크 혼잡상태에 동적으로 적응하기 위한 연구로는 송신자기반기법과 수신자기반 기법이 있는데, 전자는 수신자들의 평균 손실률에 따른 전송률로 가용 대역폭이 높은 수신자의 대역폭 낭비가 발생하며, 후자는 수신자들의 가용 대역폭에 따른 레이어(layer)를 동적으로 나누는 방법이 부족하다. 이를 위해 본 논문에서는 수신자의 네트워크 상태에 따라 정상상태와 혼잡상태로 구분하는 두 개의 멀티캐스트 그룹을 형성하고, 수신자가 손실률에 따라 동적으로 그룹을 선택함으로써 대역폭에 적합한 품질의 서비스를 받을 수 있도록 하는 대역폭 관리 알고리즘을 설계한 후 이를 구현하였다. 실험을 통한 결과를 살펴볼 때 수신자는 손실률에 따라 적합한 그룹을 선택함으로써 대역폭 낭비가 발생하는 문제점을 개선할 수 있었다.

• Journal of Communications and Networks
• /
• 제18권3호
• /
• pp.513-522
• /
• 2016

We propose a mechanism for monitoring load in quality of service (QoS)-enabled wireless networks and show how it can be used for network management as well as for dynamic pricing. Mobile network traffic, especially video, has grown exponentially over the last few years and it is anticipated that this trend will continue into the future. Driving factors include the availability of new affordable, smart devices, such as smart-phones and tablets, together with the expectation of high quality user experience for video as one would obtain at home. Although new technologies such as long term evolution (LTE) are expected to help satisfy this demand, the fact is that several other mechanisms will be needed to manage overload and congestion in the network. Therefore, the efficient management of the expected huge data traffic demands is critical if operators are to maintain acceptable service quality while making a profit. In the current work, we address this issue by first investigating how the network load can be accurately monitored and then we show how this load metric can then be used to provide creative pricing plans. In addition, we describe its applications to features like traffic offloading and user satisfaction tracking.