• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.233-240
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• 2000

Nuclear power plant structures may be exposed to aggressive environmental effects than may cause their strength and stiffness to decrease over their service lives, Although the physics of these damage mechanisms are reasonably well understood and quantitative evaluation of their effects on time-dependent structural behavior is possible in some instances such evaluations are generally very difficult and remain novel. The assessment of existing RC containment in nuclear power plants for continued service must provide quantitative evidence that they are able to withstand future extreme loads during a service period with an acceptable level of reliability. Rational methodologies to perform the reliability assessment can be developed from mechanistic models of structural deterioration using time-dependent structural reliability analysis to take earthquake loading uncertainties into account. The final goal of this study is to develop the reliability analysis of RC containment structures. The cause of the degrading is first clarified and the reliability assessment has been conducted. By introducing stochastic analysis based on random vibration theory the reliability analysis which can determine the failure probabilities has been established.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.719-726
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• 2005

The optimal design was performed for the bridge superstructure composed of steel box girders and concrete deck considering life cycle cost. The service life of the superstructure was estimated, after load carry capacity curves for steel girder and concrete deck were derived on the basis of condition grade curves and maintenance histories. The object function was determined as life cycle cost, including initial cost, total maintenance cost, disposal cost and user cost, for a period of the estimated service life. The optimal design of the superstructure was performed for the various service lifes. The annual costs were used to compare calculated results and to get the most economical design. Also this paper presents reasonable idea for the use of user cost with uncertainty.

• Korean Journal of Organic Agriculture
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• v.25 no.3
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• pp.523-536
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• 2017

The purpose of this study is to present operating directions of school food service center (SFSC) for development of environment-friendly agricultural producers (EFAP) and regional agriculture. Of eight SFSCs being operated in Chungcheongnam-do, this study analyzed situations of three cases, Cheonan, Asan and Hongseong. The analysis on operation situations revealed that all the three cases had positive economic effects on EFAP in the aspect of low commission and fixed supply price for a given period. The survey showed that social and economic changes since participating in the SFSC were largest in Asan. The awareness of the economic effects was largest among the producers in Cheonan.

• International journal of advanced smart convergence
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• v.3 no.2
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• pp.18-21
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• 2014

A control application requirements currently used is very low, such as packet loss rate, minimum delay on sensor networks with quality of service (QoS) requirements some packet delivery guarantee. This paper is the sampling period at the end of the actuator and sensor data transfer related to the Miss ratio for each source sensor node, use the controller and the internal ANFIS. The proposed scheme has the advantages of simplicity, scalability, and General. Simulation results of the proposed scheme can provide QoS support in WSANs.

• Korean Management Science Review
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• v.17 no.2
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• pp.87-95
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• 2000

This paper presents two analytical approaches to determine the vehicle fleet size for container shuttle service. The shuttle service can be defined as the repetitive travel between the designated places during working period. In the first approach, the transportation model is adopted in order to determine the number of vehicles required. Its advantages and disadvantages in practical application are also discussed. In the second approach, a logical network which is oriented on job is transformed from a physical network which is focused on demand site. Nodes on the logical network represent jobs which include loaded travel, loading and unloading and arcs represent empty travel for the next jobs which include loaded travel, loading and unloading and arcs represent empty travel for the next job. Then a mathematical formulation is constructed similar to the multiple traveling salesman problem (TSP). A solution procedure is carried out based on the well-known insertion heuristic with the real world data.

• Satellite Communications and Space Industry
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• v.13 no.1 s.28
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• pp.118-124
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• 2006

HAPS(High Altitude Platform Station) which is defined as a station located on an object at an altitude of 20 to 50 km and at a specified, nominal, fixed point relative to the earth is promising technology capable of providing broadband multimedia services. In this study, economical aspects of HAPS service are analyzed by estimating the revenue and costs incurred by the service. To evaluate the profitability of HAPS service, the number of subscribers is estimated and then the net present value (NPV), payback period, and the rate of return on investment (ROI) are calculated under various scenarios

• Communications of the Korean Mathematical Society
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• v.13 no.2
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• pp.393-403
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• 1998

We consider $M_1,M_2/M/1$ retrial queues with two classes of customers in which the service rates depend on the total number or the customers served since the beginning of the current busy period. In the case that arriving customers are bloced due to the channel being busy, the class 1 customers are queued in the priority group and are served as soon as the channel is free, whereas the class 2 customers enter the retrical group in order to try service again after a random amount of time. For the first $N(N \geq 1)$ exceptional services model which is a special case of our model, we derive the joint generating function of the numbers of customers in the two groups. When N = 1 i.e., the first exceptional service model, we obtain the joint generating function explicitly and if the arrival rate of class 2 customers is 0, we show that the results for our model coincide with known results for the M/M/1 queues with smart machine.

• Journal of Korean Public Health Nursing
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• v.24 no.1
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• pp.61-70
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• 2010

Purpose: This study analyzed outcomes of a Telecare case management service pilot project for Korean Medicaid Program Clients in Seoul. Outcome data for provided services and medical aid cost data were analyzed. Methods: Case management services were delivered by 10 medical aid managers. The period of the project was from July to December 2007. Results: The total number of the objects was 9714, representing 43.4% of the total medical aid clients in the area. The average number of consults was 2.58. Consults were most frequently via letter and telephone, with in- person visits being least common. Of the total, 213 cases were referred to community services, 87.8% were transacted successfully. The medical expenditure was less than that from January-June, 2007. Conclusion: Telecare service via mail or telephone allows contact with many clients in a short time which can enable the discover and monitoring of high risk clients. This can be accomplished at a cost savings to the Korean Medicaid Program.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.333-336
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• 1996

This paper is an exploratory study aimed at finding factors that influence the penetration of cellular mobile telecommunications which have seen rapid development since 1980s. The paper tries to find economy and policy variables to influence the penetration by means of the multiple regression analysis. This paper shows a model that explain the penetration ratio of cellular service. The model is based on data from 39 upper middle income and 39 high income countries. The result shows that GDP per capita and the service period of the cellular mobile telecommunication have influenced on the penetration ratio positively, and the tariff of the service negatively. But, it is the open area to study the impact of the telecommunications policy changes on penetration, and to set a model which could explain the nation-specific characteristics.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.3
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• pp.107-117
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• 2014

The personal information extrusion accident(hacking, improper maintenance) by the internet has been increased rapidly during the last ten-year period. The personal information includes Korean resident registration number, name, cellphone number, home telephone number, E-mail address, home address, etc. Korean resident registration number is unchangeable from the cradle to the grave. Illegally accessed personal information can be wrongfully resoled or used at phishing scam. In this paper, we propose a alternative means of Korean resident registration number using the authorized certificate. The authorized certificate is in use safely in Internet. The authorized certificate(included Chinese name) is in used in offline service, the authorized certificate(included English name) is used in online(for government service) and the authorized certificate(not included name) is used in online(for private service). The authorized certificates are possible for discard, republication. The method can reduce the possibility of the personal information extrusion.