• Journal of Korean Society of Transportation
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• v.17 no.1
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• pp.41-52
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• 1999

Recently, much literature has surveyed the economic effects of transportation investment, focusing on the relationship between transportation infrastructure investment and economic development. Although the conventional views assume that transportation investment stimulates economic growth, the results of recent studies are not conclusive and in some cases reject the conventional views. The contradictory results are linked with double counting Problem and Keynesian/Neo-classical economics theory. This article investigates the economic effects of road transportation with regard to freight transport using Stated Preference technique. This study examines, in particular, the value of time saving for freight which has been rarely studied in this area. In the first part, the value of time saving, excluding the value for driver and operating cost, is theoretically investigated through the model of continuous review system and periodic review system. At last, the empirical study using the Seated Preference technique shows the value of time saving for freight and the value of reliability, compared with other studies and the value of those in COBA. The result makes us conclude that road investment produces the secondary effects as well as the direct benefit such as time saving for passengers, operating cost saving. and accident cost reduction. The secondary effect includes the contribution to economic development.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.1
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• pp.1-9
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• 2007

At present various methods relating resource access control in grid environment are being studied. Most of the access authorization to grid resource is designed fit to the attributes and the role of user. But resource access control is to be made in the respect of business model to activate grid. Therefore this study suggests a model that can operate resource access control driven by grid accounting information. On the base of collection of accounting information about grid job, processing cost is yielded. If the user's available fund is less than processing cost, it gets to control grid job by the resource access control policy. Finally when grid job is completed, user is assigned to pay the charges for using resource of supplier. Then resource provider gets to supply stable resource in grid by participating it voluntarily to use idle resource. This study is esteemed to realize utility computing environment correspondent to economic principle by ensuring resource access policy of organizations which participate in grid.

• Journal of IKEEE
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• v.14 no.3
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• pp.236-243
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• 2010

Power quality mitigation devices play an important role in lots of industrial segments. Although there were many devices available in the market, the selection of an appropriate device specially for voltage sags and interruptions mitigation has been a challenge in the utility and customer for several years. It usually depends on technical and economic characteristics of the device. Nevertheless, most mitigation method is selected by rule of thumb or empirical method. In this paper, the life cycle cost analysis for the probabilistic risk assesment of voltage sag mitigation method is performed using either the deterministic or probabilistic approach. The difference between a deterministic and a probabilistic cost analysis approach is illustrated with five different case studies. This paper not only provides a comparison of life cycle costing of various devices but it also indirectly shows the possible savings due to the mitigation of voltage sags in the form of a project balance chart.

• Journal of Industrial Convergence
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• v.17 no.4
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• pp.131-137
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• 2019

In infrastructure wireless mesh networks (WMNs), in order to improve mobile users' satisfaction for the given cache hit ratio, we investigate an User centric Cache Allocation (UCA) scheme while reducing cache cost in a mesh router (MR) and expected transmission time (ETT) for content search in cache. To minimize ETT values of mobile users, a genetic algorithm based UCA (GA-UCA) scheme is provided. The goal is to maximize mobile users' satisfaction via our well defined utility, which considers content popularity and the number of mobile users. Finally, through solving optimization problem we show the optimal cache can be allocated for UCA and GA-UCA. Besides, a WMN provider can find the optimal number of mobile users for user centric cache allocation in infrastructure WMNs.

• Journal of the Korean Institute of Landscape Architecture
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• v.29 no.3
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• pp.81-89
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• 2001

The purpose of this research is to provide for some useful data for computer-related courses of the landscape science, assuming that computers are being and should be used more and more in landscape architecture and therefore, that landscape science students need to respond positively to such a trend. For this purpose, landscape architecture studios and their landscape architects were surveyed for their computer and its program uses as well as their satisfaction with the utility of computer for their landscape works. The results of this research are as follows; 1) 10.7% of the landscape architects surveyed answered that they had learned about their necessary softwares at school, while 61.6% of the studios surveyed were less satisfied with their employees' poor computing ability. Such findings suggest a lack of computer-related courses in landscape science and therefore, that more computer-related courses should be introduced for landscape science students together with the necessary software education. 2) Too few landscape softwares are being used by the landscape architecture studios; such softwares as AutoCAD, Photoshop, 3D Max, Excel, PowerPoint and 한글 account for more than 90% of the landscape architecture softwares being used currently. Quite naturally, landscape students need to be trained on these softwares above all. 3) It was found hat he area of work using the computer most was ˝design works˝(84.5%), followed by ˝documentation˝(83.8%), ˝image editing˝(75.1%), ˝cost calculation˝(68.2%), ˝presentation˝(68.1%), ˝analysis˝(37.8%) and ˝rendering˝(35%). It was regretable to discover that such areas requiring more computing work as ˝analysis˝ and ˝rendering˝ were still worked manually. So it sis deemed necessary for landscape science courses to enhance their computer education of such areas first of all.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.20 no.1
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• pp.26-33
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• 2012

Competition between air transportation and railways has grown fiercer in major countries around the world with the rise of high-speed railways. In South Korea, air passenger travel has been rapidly decreasing since the initial launch of the Seoul-Pusan KTX line in 2004 and second opening that followed in 2010. Further expansion of the high-speed railway is expected. At present, research efforts to verify the validity of constructing an underwater express railway tunnel between Ho-nam and Jeju Island are taking place. Considering the possible high speed railway connection between Seoul and Jeju Island, this thesis has analyzed the choice behavior of existing passengers of the major and low-cost carriers. For this, Stated Preference (SP) research has been performed for three variables, including fare, travel time and the number of runs, to estimate the substitution rate of each of the three variables. Binomial Logit Model has been estimated with the obtained data. The estimation of the model has found that airline passengers of major and low-cost carriers are willing to pay approximately 7,200 KRW and 5,000 KRW, respectively, to reduce travel time by one hour. If the number of runs in one day increases, it has been estimated that the passengers are willing to pay additional fares of about 390 KRW and 30 KRW, respectively. On the other hand, the substitution rate between the number of runs and the travel time was found to be somewhat insignificant. If the construction of the Seoul-Jeju line progresses in the future, this study could be used as preliminary data for determining fares, travel time and the number of runs.

• Nuclear Engineering and Technology
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• v.16 no.4
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• pp.181-194
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• 1984

The in-core fuel management problem was studied by use of the calculus of variations. Two functions of interest to a public power utility, the profit function and the cost function, were subjected to the constraints of criticality, the reactor turnup equations and an inequality constraint on the maximum allowable power density. The variational solution of the initial profit rate demonstrated that there are two distinct regions of the reactor, a constant power region and a minimum inventory or flat thermal flux region. The transition point between these regions is dependent on the relative importance of the profit for generating power and the interest charges for the fuel. The fuel cycle cost function was then used to optimize a three equal volume region reactor with a constant fuel enrichment. The inequality constraint on the maximum allowable power density requires that the inequality become an equality constraint at some points in the reactor. and at all times throughout the core cycle. The finite difference equations for reactor criticality and fuel burnup in conjunction with the equality constraint on power density were solved, and the method of gradients was used to locate an optimum enrichment. The results of this calculation showed that standard non-linear optimization techniques can be used to optimize a reactor when the inequality constraints are properly applied.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.4
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• pp.359-371
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• 2001

Project scheduling under resource constraint conditions have contained to many uncertain factors and it is perfonned by human experts. The expert identifies the activities of the project, decides the precedent relationships between these activities, and then construct the schedule using expected activity's duration. At this time, most of the scheduling methods concentrate on one of scheduling factor between activity duration and cost. And the activity duration, which is the most important factor in scheduling, is decided by heuristic of expert. Therefore it may cause uncertainty of activity duration decision and the use of this activity duration may increase the uncertainty of constructed schedule. This paper proposes Fuzzy-MOEH scheduling algorithm, which is the aggregation of the fuzzy number for deciding activity duration and applies the cost function for solving the problems of previous scheduling methods. This paper also analyze the utility and property of Fuzzy-MEOH algorithm through the comparison between Fuzzy-MEOH algorithm and existing MEOH algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.7
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• pp.861-868
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• 2019

Various server-based services such as big data, IoT and artificial intelligence have been made online. As a result, the demand for IDC to support stable server operation is increasing. IDC is a server-based facility with a stable line and power supply facility that manages 20 to 30 servers in an efficiently separated rack-level subnetwork. Here, we need a way to efficiently manage servers security, firewall, and traffic on a rack-by-rack basis. Including traffic shaping capabilities that control routers, firewalls, IPS, and line speeds, as well as VPN technology, a recent interest. If three or five kinds of commercial equipment are adopted to support this, it may be a great burden to the management cost as well as the introduction cost. Therefore, in this paper, we propose a method to implement the five functions in one rack-unit small integrated security router. In particular, IDC intends to integrate traffic shaping and IPS, which are essential technologies, and to propose the utility accordingly.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.4
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• pp.1-15
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• 2020

As cities expand and underground utilities construction projects increase, there is an urgent need for a technology capable of analyzing the underground utilities network in 3D. Since 2015, 3D Underground Geospatial Map project, that has been integrating 15 types of underground information such as underground utilities, underground structures, and ground information, is in progress in S. Korea. However, the construction of 3D underground facilities is currently based on manual work and the logic for building a 3D model is very complicated. And it takes a lot of time and cost to process millions of large amounts of data per local governments. By presenting a framework on the processing and partial updating of the 3D underground utilities model, this paper aims to establish a plan to quickly build a 3D underground utility model at a minimum cost. The underground utilities processing and partial update automation technologies developed in this study are expected to be immediately applied to the 3D Underground Geospatial Map project.