• Title/Summary/Keyword: Replacement Cycle

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Reliability-based Life Cycle Cost Analysis for Optimal Seismic Upgrading of Bridges

  • Alfredo H-S. Ang;Cho, Hyo-Nam;Lim, Jong-Kwon;An, Joong-San
    • Computational Structural Engineering : An International Journal
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    • v.1 no.1
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    • pp.59-69
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    • 2001
  • This study is intended to propose a systematic approach for reliability-based assessment of life cycle cost (LCC) effectiveness and economic efficiency for cost-effective seismic upgrading of existing bridges. The LCC function is expressed as the sum of the upgrading cost and all the discounted life cycle damage costs, which is formulated as a function of the Park-Ang damage index and structural damage probability. The damage costs are expressed in terms of direct damage costs such as repair/replacement costs, human losses and property damage costs, and indirect damage costs such as road user costs and indirect regional economic losses. For dealing with a variety of uncertainties associated with earthquake loads and capacities, a simulation-based reliability approach is used. The SMART-DRAIN-2DX, which is a modified version of the well-known DRAIN-2DX, is extended by incor-porating LCC analysis based on the LCC function developed in the study. Economic efficiencies for optimal seismic upgradings of the continuous PC segmental bridges are assessed using the proposed LCC functions and benefit-cost ratio.

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Analysis of Economic Replacement Cycle of Power Transformer Based on LCC Considering Maintenance Effect

  • Park, Seung-Hwa;Jang, Kyeong-Wook;Kweon, Dong-Jin;Shon, Jin-Geun
    • Journal of Electrical Engineering and Technology
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    • v.13 no.4
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    • pp.1631-1637
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    • 2018
  • Electric utilities has been considered the necessity to introduce asset management of electric power facilities in order to reduce maintenance cost of existing facilities and to maximize profit. This paper aims to provide data that can helpful to make profitable decision in terms of power transformers which have a significant part in the power system. Therefore, this study is modeling input cost for power transformer during its entire life and also the life cycle cost (LCC) technique is applied. In particular, the variation of transformer state related with maintenance and the variation of the EUAC curve based on cost and effect of maintenance is examined. In this study, the trend of the equivalent uniform annual cost (EUAC) according to maintenance cycle and cost of equipment is analyzed. In line with that, sensitivity analysis influenced by the changes of other cost factors was performed.

Article Data Prefetching Policy using User Access Patterns in News-On-demand System (주문형 전자신문 시스템에서 사용자 접근패턴을 이용한 기사 프리패칭 기법)

  • Kim, Yeong-Ju;Choe, Tae-Uk
    • The Transactions of the Korea Information Processing Society
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    • v.6 no.5
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    • pp.1189-1202
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    • 1999
  • As compared with VOD data, NOD article data has the following characteristics: it is created at any time, has a short life cycle, is selected as not one article but several articles by a user, and has high access locality in time. Because of these intrinsic features, user access patterns of NOD article data are different from those of VOD. Thus, building NOD system using the existing techniques of VOD system leads to poor performance. In this paper, we analysis the log file of a currently running electronic newspaper, show that the popularity distribution of NOD articles is different from Zipf distribution of VOD data, and suggest a new popularity model of NOD article data MS-Zipf(Multi-Selection Zipf) distribution and its approximate solution. Also we present a life cycle model of NOD article data, which shows changes of popularity over time. Using this life cycle model, we develop LLBF (Largest Life-cycle Based Frequency) prefetching algorithm and analysis he performance by simulation. The developed LLBF algorithm supports the similar level in hit-ratio to the other prefetching algorithms such as LRU(Least Recently Used) etc, while decreasing the number of data replacement in article prefetching and reducing the overhead of the prefetching in system performance. Using the accurate user access patterns of NOD article data, we could analysis correctly the performance of NOD server system and develop the efficient policies in the implementation of NOD server system.

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A STUDY ON THE LIFE CYCLE COST ANALYSIS IN LIGHT RAIL TRANSIT BRIDGES: FOCUSED ON SUPERSTRUCTURE

  • Lee Du-heon;Kim Kyoon-tai;Kim Hyun Bae;Jun Jin-taek;Han Choong-hee
    • International conference on construction engineering and project management
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    • 2007.03a
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    • pp.30-40
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    • 2007
  • The demand for light-rail construction projects has recently been increasing, and they are mostly supervised by private construction companies. Therefore, a private construction company that aim to raise gains from the operation of the facilities during the contract period greater than what they invested should b able to accurately calculate the costs from the aspect of Life Cycle Cost (LCC). In particular, a light-rail transit bridge that has a heavier portion from the aspect of the cost of light-rail transit construction requires a more accurate calculation method than the conventional LCC calculation method. For this, an LCC analysis model was developed and a cost breakdown structure was suggested based on literature review. The construction costs by shape of the upper part of a light-rail transit were calculated based on the cost breakdown system presented in this paper, and the cost generation cycle and cost unit price were collected and analyzed based on records on maintenance costs, rehabilitation and replacement. In addition, after forming some hypotheses in order to perform the LCC analysis, economic evaluation was conducted from the aspect of the LCC by using performance data by item.

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A STUDY ON THE LIFE-CYCLE FOR SELECTING A GRATING

  • Yun-Sik Kim;Dong-Wan Kang;Taehoon Hong;Chang-Taek Hyun
    • International conference on construction engineering and project management
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    • 2009.05a
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    • pp.1189-1194
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    • 2009
  • A gutter-shaped U grating is a facility that is installed at the sides of a road to provide pedestrians with a rainwater-free road. The previous studies on this facility focused mainly on the progress of the efforts that are being made to improve its performance and interception efficiency so as to prevent damages in regional areas due to the heavy rains caused by climate change. The studies on its maintenance, however, are still inadequate. Therefore, this study was conducted to analyze and compare the life cycle costs and performance evaluations of the steel and magic gratings, which are installed in apartments. The results of the study show that the replacement period and rate of gratings differ depending on where they are installed. The initial capital investment cost of a magic grating installed at a road where many vehicles pass is quite high, but in terms of its maintenance and entire-life-cycle costs, its total expenses are lower than those of a steel grating. The results of this study are expected to serve as preliminary data for the selection of an adequate grating that is suitable for particular places in the design phase of construction projects.

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Leakage Current Characteristics of 18kv ZnO Lightning Arresters by Accelerated Aging Test (가속열화시험에 의한 18kV ZnO 피뢰기의 누설 전류 특성 분석)

  • Kim, Ju-Yong;Song, Il-Geun;Kim, Chan-Yeong;Mun, Jae-Deok
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.51 no.2
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    • pp.62-67
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    • 2002
  • This paper provides the results of accelerated aging test of 18kV ZnO lightning arresters to investigate the leakage current characteristics. It was impossible to establish the replacement criterion for field operating lightning arrester because conventional aging test was only focused on the aging of ZnO elements. In general, it is possible to replace the aged arresters before the failure in the field using the leakage current measurement because it must be increased by the aging. But we can not use the method because we don't know the characteristics of the installed lightning arresters. Therefore in this paper we applied operating voltage and accelerating cycle which consists of temperature and humidity to the arresters. Then we measured the variation of total and resistive leakage current and found out the characteristics of the acted lightning arresters.

A Study of Determination on Usage Life of Production Facilities for Economic LCC (경제적 LCC 를 위한 생산설비의 사용년수에 관한 연구)

  • Yoo, Il-Geon;Park, Won-Jun
    • IE interfaces
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    • v.6 no.2
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    • pp.37-51
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    • 1993
  • This paper studies the economic replacement method for production facilities which requires huge investment but are necessary for higher productivity and competability of products. That is, the general models for the decision of economic life of properties which minimizes the total costs throughout the usage life(Life cycle costs) are generated. Main factors which make influences for the decision of econmic life can be divided by three. These are the change of salvage value, repair and maintenance costs, and availability of production facilities with the passage of usage time. In this paper, the real world data for these three factors are collected and analyzed for the extraction of representative standard forms with the passage of time. And general models for economic replacement methods and optimal usage terms are presented through tables with the combination of the standard forms of these three main factors.

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A Study on Design and Cache Replacement Policy for Cascaded Cache Based on Non-Volatile Memories (비휘발성 메모리 시스템을 위한 저전력 연쇄 캐시 구조 및 최적화된 캐시 교체 정책에 대한 연구)

  • Juhee Choi
    • Journal of the Semiconductor & Display Technology
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    • v.22 no.3
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    • pp.106-111
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    • 2023
  • The importance of load-to-use latency has been highlighted as state-of-the-art computing cores adopt deep pipelines and high clock frequencies. The cascaded cache was recently proposed to reduce the access cycle of the L1 cache by utilizing differences in latencies among banks of the cache structure. However, this study assumes the cache is comprised of SRAM, making it unsuitable for direct application to non-volatile memory-based systems. This paper proposes a novel mechanism and structure for lowering dynamic energy consumption. It inserts monitoring logic to keep track of swap operations and write counts. If the ratio of swap operations to total write counts surpasses a set threshold, the cache controller skips the swap of cache blocks, which leads to reducing write operations. To validate this approach, experiments are conducted on the non-volatile memory-based cascaded cache. The results show a reduction in write operations by an average of 16.7% with a negligible increase in latencies.

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Effect of Ground Granulated Blast-Furnace Slag on Life-Cycle Environmental Impact of Concrete (고로슬래그가 콘크리트의 전 과정 환경영향에 미치는 효과)

  • Yang, Keun-Hyeok;Seo, Eun-A;Jung, Yeon-Back;Tae, Sung-Ho
    • Journal of the Korea Concrete Institute
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    • v.26 no.1
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    • pp.13-21
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    • 2014
  • To quantitatively evaluate the influence of ground granulated blast-furnace slag (GGBS) as a supplementary cementitious material on the life-cycle environmental impact of concrete, a comprehensive database including 3395 laboratory mixes and 1263 plant mixes was analyzed. The life-cycle assesment studied for the environmental impact of concrete can be summarized as follows: 1) the system boundary considered was from cradle to pre-construction; 2) Korea life-cycle inventories were primarily used to assess the environmental loads in each phase of materials, transportation and production of concrete; and 3) the environmental loads were quantitatively converted into environmental impact indicators through categorization, characterization, normalization and weighting process. The life-cycle environmental impacts of concrete could be classified into three categories including global warming, photochemical oxidant creation and abiotic resource depletion. Furthermore, these environmental impacts of concrete was significantly governed by the unit content of ordinary portland cement (OPC) and decreased with the increase of the replacement level of GGBS. As a result, simple equations to assess the environmental impact indicators could be formulated as a function of the unit content of binder and replacement level of GGBS.