• Journal of the Korean Data and Information Science Society
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• v.14 no.2
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• pp.393-403
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• 2003

In this paper, various replacement policies for the general failure model are considered. There are two types of failure in the general failure model. One is Type I failure (minor failure) which can be removed by a minimal repair and the other is Type II failure (catastrophic failure) which can be removed only by a complete repair. In this model, when the unit fails at its age t, Type I failure occurs with probability 1-p(t) and Type II failure occurs with probability p(t), $0{\leq}p(t){\leq}1$. Under the model, optimal replacement policies for the long-run average cost rate and the limiting efficiency are considered. Also taking the cost and the efficiency into consideration at the same time, the properties of the optimal policies under the Cost-Priority-Criterion and the Efficiency-Priority-Criterion are obtained.

• Journal of Information Technology Applications and Management
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• v.11 no.4
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• pp.121-132
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• 2004

This paper surveyed 30 system designers and developers who had been participating in a project for five months to examine the usefulness of design artifacts for object-oriented system development. A set of nine requirement and design documents was selected in consideration of the IEEE guidelines. Overall the respondents appeared to agree that the artifacts were useful for system development. On the other hand, the contribution of design artifacts to maintenance was rated lower due to the frequent changes over the iterative process. Of the artifacts, considered more useful were use case specifications, UI design and operation specifications. The respondents were the most reluctant to write test cases. Designers did not like to document more details in the design artifacts than did developers. A future study is required to determine the economics end change management of documentation.

• Journal of KIBIM
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• v.5 no.2
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• pp.34-45
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• 2015

As buildings become larger and more complicated, construction costs have increased with a considerable effect on buildings' Life Cycle Cost (LCC). However, there has been little consideration on economic aspects in the selection of construction materials due to limited information on the materials and dependency in architects' experience and inefficiency in cost estimation, causing design changes, increase in maintenance cost, difficulty in budgeting, and decrease in building performance. To solve these problems, this study proposed a BIM-based material selection model which reflects the comprehensive economic efficiency of building materials. Our cost prediction model can estimates the material-related cost during the entire building life cycle. Furthermore, we implemented the proposed model in connection with BIM, which can analyze and compare LCC by material. Through the validation of the model, we could confirm the necessity of LCC-based material selection in comparison with the conventional cost-centered material selection.

• Journal of Korean Society of Rural Planning
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• v.2 no.1
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• pp.79-90
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• 1996

In recent year, construction of national infrastructure, variations of agricultural environment, urbanization of rural life-style, and other things have influenced on rural area. Therefore, its landscapes have been changed rapidly. As a result of it, rural landscape should be controlled with amenity and totality. That is a rural amenity control planning. The purposes of this study is to consider characters of rural settlement area, the directions of landscape control planning as an environmental planning, the structure of rural landscape, the process of rural landscape control planning, and its frameworks. Main viewpoints of landscape control planning in rural settlement are as follows; the using of regional resources, the harmony of surrounding environments, the harmony of natural ecology, locating of facilities, the development of new landscape material, maintenance of sequencing, symbolizing, unificating, and opening, the using of natural/regional materials, the using of waterfront, the making of stories.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.62 no.2
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• pp.65-71
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• 2013

Nonlinear loads with harmonics exist in an actual power system where harmonic currents make voltage distortion. The sum of reactive power measured at individual load is different from the measured reactive power at a bus in a power system with linear and non-linear loads. In this study, ANN(artificial neural network) load modeling technique with consideration of harmonics is introduced for more accurate component load modeling and an impact coefficient is proposed for aggregation of component loads. Results of this research show more accurate load modeling method. Since precise data for power system analysis can be acquired, the proposed method will be used for power system planning and maintenance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.10
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• pp.1720-1725
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• 2008

Because of the continuous increasing of energy consumption, metallic pipelines are widely used to supply services to customers such as gas, oil, water, etc. Most common metallic pipelines are underground and are now frequently being installed in nearby electric power lines. In recent years, buried gas pipeline close to power lines can be subjected to hazardous induction effects, especially during single line to ground faults. because it can cause corrosion and it poses a threat to the safety of workers responsible for maintenance. Accordingly, it is necessary to take into consideration for analysis of induced voltage on gas pipelines in transmission lines. This paper analyzed the induced voltage on the gas pipelines due to the 154kV transmission lines in normal case and in different faulty case conditions using EMTP (Electro-Magnetic Transients Program).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.10
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• pp.1171-1176
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• 2009

This paper provides how to establish an integrated plan for LE (life extension) and MD (modernization) of aged hydropower plants. The methodology is developed through review of overseas/domestic LE/MD histories, investigation of the previous overseas methodologies and consideration of domestic practices. The methodology includes reviews of the various factors such as condition, operation and maintenance history, up-to-date technology, and economic benefit. In order to establish the life extension/modernization plan, the methodology is applied to the domestic aged hydropower plants. Finally, priority rankings and draft practice plans for LE/MD are derived.

• Smart Structures and Systems
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• v.11 no.1
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• pp.103-122
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• 2013

It is essential to update the model with reflecting observation or inspection data for reliability estimation of existing structures. Authors proposed updated reliability analysis by using Particle Filter. We discuss how to apply the proposed method through numerical examples on reinforced concrete structures after verification of the method with hypothetical linear Gaussian problem. Reinforced concrete structures in a marine environment deteriorate with time due to chloride-induced corrosion of reinforcing bars. In the case of existing structures, it is essential to monitor the current condition such as chloride-induced corrosion and to reflect it to rational maintenance with consideration of the uncertainty. In this context, updated reliability estimation of a structure provides useful information for the rational decision. Accuracy estimation is also one of the important issues when Monte Carlo approach such as Particle Filter is adopted. Especially Particle Filter approach has a problem known as degeneracy. Effective sample size is introduced to predict the covariance of variance of limit state exceeding probabilities calculated by Particle Filter. Its validity is shown by the numerical experiments.

• The Journal of the Korea Contents Association
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• v.6 no.4
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• pp.117-124
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• 2006

This study was to analyze web contents of major cultural tourism festival. And suggest to contents development. Study method is contents analysis and comparative study by suggest data. According to the results, need for independent domain, provide to foreign language information, maintenance membership administration through membership e-mail service, provide to segmentation board, provide to dynamic information should be consideration to visitror's movement line.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.16 no.1
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• pp.56-64
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• 2020

The safety related heat exchangers have been evaluated for their performance during the operation of the nuclear power plant. The evaluation program for the safety related heat exchanger was developed in 2010 and used by KHNP based on EPRI TR-10739 algorithms. The spend fuel pool heat exchanger is one of the safety related heat exchanger in the nuclear power plant and also evaluated for their performance. Recently the performance evaluation for the spend fuel pool heat exchanger was not available because of the decreased heat in the spend fuel pool due to the long term overhaul. This paper analyzes the main cause of evaluation failure in the evaluation process and suggests the criteria for the heat exchanger performance evaluation during the long term overhaul.