• Journal of Korean Institute of Industrial Engineers
• /
• v.13 no.2
• /
• pp.65-77
• /
• 1987

Congestion occurs whenever users interfere with each other, while competing for scarce resources. In a congested market, such as a telecommunication service market, users of telecommunication services incur costs in using the service in addition to the price. The user's own time costs involved in learning to use the service, waiting for the service, and making use of the service are typically greater than the price of telecommunication services. A market equilibrium analysis is performed in which a method for user demand aggregation is developed. The effects of price changes on user demands and market demands for congested services are examined. It is found that total market demands may increase as the price for less-congested services increase under certain demand conditions. This suggests that a nonuniform pricing scheme for a congested service may improve the utilization of the congested system. The sign of price cross-elasticity for congested services is show to vary with demand conditions. A possible complementary property of congested services is found and the implication of such a property is discussed. It is argued that such a complementary property may lead to a cross subsidy in a market with congestion. Finally, comparisons between uniform pricing and nonuniform pricing policies are made. A specific numerical example is given to show that a nonuniform pricing policy may be Pareto superior to a uniform pricing policy.

• The Journal of the Korea Contents Association
• /
• v.19 no.6
• /
• pp.236-248
• /
• 2019

Green belts can help to set boundary for city growth, provide ecological protection system and enhance the resilience of Beijing. During the implementation period of the current overall city planning of Beijing, the proportion of green space varies much among the sub-districts, villages and towns involved in the two green belts in the research. With this as starting point, by researching the correlations of 'city system factors' and 'planning policy factors' with the change in the scale of green space, the paper discussed the influential factors of implementing the planning of green space of Beijing, and conducted quantitative research, with such possible influential factors classified into 'city system factors' and 'planning policy factors'. Through multiple linear regression model, the paper tested the correlations of city system factors and planning policy factors (independent variable) with the increment in the construction land in green belts (dependent variable). Through influence to population aggregation and the expansion force of construction land, city system factors such as mountain land and water, house rent of unit area, accessibility of public transport and the newly-defined state-owned construction land generate correlation with the change in the scale of construction land in green belts.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.18 no.2
• /
• pp.327-347
• /
• 2024

Edge computing is frequently employed in the Internet of Vehicles, although the computation and communication capabilities of roadside units with edge servers are limited. As a result, to perform distributed machine learning on resource-limited MEC systems, resources have to be allocated sensibly. This paper presents an Improved MADDPG algorithm to overcome the current IoV concerns of high delay and limited offloading utility. Firstly, we employ the MADDPG algorithm for task offloading. Secondly, the edge server aggregates the updated model and modifies the aggregation model parameters to achieve optimal policy learning. Finally, the new approach is contrasted with current reinforcement learning techniques. The simulation results show that compared with MADDPG and MAA2C algorithms, our algorithm improves offloading utility by 2% and 9%, and reduces delay by 29.6%.

• The KIPS Transactions:PartD
• /
• v.11D no.7 s.96
• /
• pp.1349-1356
• /
• 2004

The interest of version management is increasing in electronic commerce requiring data mining and documents processing system related to digital governmentapplications. In this paper, we define a change set that is to manage historicalinformation and to maintain XML documents during a long period of time and propose several storage policies of XML documents using a change set. A change set includes a change oper-ation set and temporal dimensions and a change operation set is composed with schema change operations and data change operations. We pro-pose three storage policies using a change set. Three storage policies are (1) storing all the change sets, (2) storing the change sets and the versions periodically. (3) storing the aggregation of change sets and the versions at a point of proper time. Also, we compare the performance between the existing storage policy and the proposed storage policies. Though the performance evaluation, we show that the method to store the aggregation of change sets and the versions at a point of proper time outperforms others.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.7
• /
• pp.3175-3181
• /
• 2012

The need of multimedia based application service is increasing as the number of smart mobile devices such as smart phone, tablet PC, and netbook is increasing rapidly and the development of application service like IPTV. There are various proposed policies to control the limited network resources. The IMS is used to control wired and wireless aggregation network to support multimedia services that are suitable to the user's need and the policy based models using the PDF of the IMS have emerged. In this paper, we propose the QoS adaption model using various protocols with the PDF of the IMS and the user scenario.

• The Journal of Fisheries Business Administration
• /
• v.48 no.2
• /
• pp.19-32
• /
• 2017

The purpose of this study is to identify problems and suggest improvements of estimating procedures and item of fisheries supply-demand statistics served as a basis for the fisheries supply-demand policies. Korea Rural Economic Institute(KREI) and Ministry of Oceans and Fisheries(MOF) respectively publish the fisheries supply-demand statistics. But the reliability of data is low as the statistics of these two organizations are limited and show discrepancy in the numbers. It is therefore difficult to use them as the basic data for policies. Also, an accurate data aggregation is difficult due to following problems in the items of statistics. 1) Problems in estimating route sales and non-route sales of production, 2) adequacy of fishery product yield rate compared to raw material in the fisheries import/export sector, 3) selection of target companies for understand stocks and survey scope of fish species, 4) applying'0'to non-edible product demand etc. In order to develop the fisheries industry as a future growth industry, it is necessary to establish the accurate fisheries supply-demand policy as the instability of fisheries supply and demand is increasing. To do this, statistical reliability has to be improved. The improvements proposed in this study should be implemented considering urgency. First of all, an exhaustive analysis of stock statistics and conversion rates of raw material yield in the fisheries import/export sector should be conducted. In the medium term and the long term, transferring production statistics to MOF and surveys on the use demand of non-food product and the level of reduced and discarded seafood products should be carried out in consecutive order.

• The KIPS Transactions:PartC
• /
• v.10C no.6
• /
• pp.727-738
• /
• 2003

Much research efforts are being exerted for the study of intrusion detection system(IDS). However little work has been for the communication medels and performance eveluation of the IDS. Here we present a communication framework for doing hybrid intrusion detection in which agents are used for local intrusion detections with a centralized data anaysis componenta for a global intrusion detection at multiple domains environment. We also assume the combination of host-based and network-based intrusion detection systems in the oberall framework. From the local domain, a set of information such as alert, and / or log data are reported to the upper level. At the root of the hierarchy, there is a global manager where data coalescing is performed. The global manager delivers a security policy to its lower levels as the result of aggregation and correlation of intrusion detection alerts. In this paper, we model the communication mechanisms for the hybrid IDS and develop a simular using OPNET modeller for the performance evaluation of transmission capabillities for the delivery of data and policy. We present and compare simulation results based on several scenarios focuding on communication delay.

• Journal of Korean Society of Transportation
• /
• v.29 no.6
• /
• pp.97-106
• /
• 2011

Mode choice model is an essential element for estimating- the demand of new means of transportation in the planning stage as well as in the establishment phase. In general, current demand analysis model developed for the mode choice analysis applies common parameters of utility function in each region which causes inaccuracy in forecasting mode choice behavior. Several critical problems from using common parameters are: a common parameter set can not reflect different distribution of coefficient for travel time and travel cost by different population. Consequently, the resulting model fails to accurately explain policy variables such as travel time and travel cost. In particular, the nonlinear logit model applied to aggregation data is vulnerable to the aggregation error. The purpose of this paper is to consider the regional characteristics by adopting the parameters fitted to each area, so as to reduce prediction errors and enhance accuracy of the resulting mode choice model. In order to estimate parameter of each area, this study used Household Travel Survey Data of Metropolitan Transportation Authority. For the verification of the model, the value of time by marginal rate of substitution is evaluated and statistical test for resulting coefficients is also carried out. In order to crosscheck the applicability and reliability of the model, changes in mode choice are analyzed when Seoul subway line 9 is newly opened and the results are compared with those from the existing model developed without considering the regional characteristics.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.8 no.3
• /
• pp.1119-1143
• /
• 2014

Lightweight trust mechanism with lightweight cryptographic primitives has emerged as an important mechanism in resource constraint wireless sensor based mobile devices. In this work, outlier detection in lightweight Mobile Ad-hoc NETworks (MANETs) is extended to create the space of reliable trust cycle with anomaly detection mechanism and minimum energy losses [1]. Further, system is tested against outliers through detection ratios and anomaly scores before incorporating virtual programmable nodes to increase the efficiency. Security in proposed system is verified through ProVerif automated toolkit and mathematical analysis shows that it is strong against bad mouthing and on-off attacks. Performance of proposed technique is analyzed over different MANET routing protocols with variations in number of nodes and it is observed that system provide good amount of throughput with maximum of 20% increase in delay on increase of maximum of 100 nodes. System is reflecting good amount of scalability, optimization of resources and security. Lightweight modeling and policy analysis with lightweight cryptographic primitives shows that the intruders can be detection in few milliseconds without any conflicts in access rights.

• Journal of Digital Convergence
• /
• v.12 no.12
• /
• pp.323-328
• /
• 2014

D-MAC protocol is used convergence network, which is designed to connect wireless link between things. This protocol is supported to local data exchange and aggregation among neighbor nodes, and distributed control packet from sink to sensor node. In this paper, we analysis about efficiency of power consumption according to whether or not security authentication of D-MAC in convergence network. If authentication scheme is applied to MAC communication, it is related to power consumption of preamble whether or not with and without authentication process. It is reduced to energy consumption against denial attack of service, when it is applied to authentication. Future work will take the effort to deal with security authentication scheme.