• Journal of the Korean Institute of Educational Facilities
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• v.24 no.6
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• pp.27-36
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• 2017

Educational facilities have an affect to make a decently learning environment. After constructed, it needs a maintenance plan to keep the performance or function which provide the repair time, repair scope and ratio. But the fundamental data are so insufficient that the field worker can't provide the maintenance plan and has no choice use the other data which concerned with apartment or office building. Above all, the service life is indispensible to make a repair plan because the repair time and scope would be provided within the service life. This study aimed at providing the method to make a service life of component in educational facilities and applying the method into the roof proof and floor finishing. Results are shown that first, it is important to set the $1^{st}$ repair time after constructed. when it proposes the three ways with the probability approach, choice probability model and cumulative cost function. Second, the service life of roof proof is provided with about 35 years. In addition, the service life of the floor finishing is about 40 years. These result would be utilized to conduct the repair plan under the service life.

• The Journal of Korean Society for Radiation Therapy
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• v.6 no.1
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• pp.21-30
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• 1994

To analyze the states of operation of radiotherapy facilities in the period from 1979 to 1992 and to get the base for efficient operation and maintenance of the radiotherapy facilities. Data on the records of annual number of patients operated by each facility; span of suspension of operation, the cost and span of repairing, and parts of oui-of-order in the period from 1979 to 1992 were analyzed. We made a comparative analysis of average annual number of patients, annual span of the suspension of operation, annual cost ratio of repair, span of repairing per break down, and total number of broken parts. We could get following annual number of patients(day), span of the suspension of span ($\%$)(day). annual cost ratio fo repair($\%$), span of repairing per break down(Min-Max, day), and number of broken parts from this analysis. 1. Cobalt unit (Picker C-9) : 10,389(43), 0.4(0.83) 0.07, 1hr-2, 3 2. Linac(Clinac 6/100) : 11,492(50), 4.0(9.57), 0.98, 1hr-30, 12 3. Linac(Clinac 18) : 9.115(44), 12.7(30.5), 3.54, 1hr-108. 41 4. Simulator(Picker Ther-X) : 2,017(9), 0.51(1.3), 0.24, 1hr-2, 7 5. RTP(Capentec Cap-plan) : 528(2), 0.4(0.93), - hrs, - The conclusion obtained from statistical analysis above are as follows. 1. The rate of operation of Cobalt unit($99.6\%$) was higher that of Linear Accelerators ($87.3\%$). The rates operation of Simulator and RTP computer were very close to that of Cobalt unit. 2. In order to raise up the working ratio of accelerator. it is desirable that we keep our engineer to learn a sufficient technical skill and the equipment agent to stock sufficient spare parts. 3. In order to maintain Linear Accelerator efficiently, it is desirable to have annually $2.3\%$ of the purchase price of equiment for repairing.

• Journal of Korean Society for Quality Management
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• v.48 no.1
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• pp.201-214
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• 2020

Purpose: The purpose of this paper is to determine an optimal number of cycle times for the replacement under the circumstance where the system is replaced at the periodic time and the multiple number of working cycles whichever occurs first and the system is minimally repaired between the replacements if it fails. Methods: The system is replaced at periodic time () or cycle time, whichever occurs first, and is repaired minimally when it fails between successive replacements. To determine the optimal number of cycle times, the expected total cost rate is optimized with respect to the number of cycle times, where the expected total cost rate is defined as the ratio of the expected total cost between replacements to the expected time between replacements. Results: In this paper, we conduct a sensitivity analysis to find the following results. First, when the expected number of failures per unit time increases, the optimal number of cycle times decreases. Second, when the periodic time for replacement becomes longer, the optimal number of cycle times decreases. Third, when the expected value for exponential distribution of the cycle time increases, the optimal number of cycle times increases. Conclusion: A mathematical model is suggested to find the optimal number of cycle times and numerical examples are provided through the sensitivity analysis on the model parameters to see the patterns for changes of the optimal number of cycle times.

• Journal of Communications and Networks
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• v.16 no.5
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• pp.493-501
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• 2014

Coverage completeness is an important indicator for quality of service in wireless sensor networks (WSN). Due to limited energy and diverse working conditions, the sensor nodes have different lifetimes which often cause network holes. Most of the existing methods expose large limitation and one-sidedness because they generally consider only one aspect, either coverage rate or energy issue. This paper presents a novel method for coverage hole detection with residual energy in randomly deployed wireless sensor networks. By calculating the life expectancy of working nodes through residual energy, we make a trade-off between network repair cost and energy waste. The working nodes with short lifetime are screened out according to a proper ratio. After that, the locations of coverage holes can be determined by calculating the joint coverage probability and the evaluation criteria. Simulation result shows that compared to those traditional algorithms without consideration of energy problem, our method can effectively maintain the coverage quality of repaired WSN while enhancing the life span of WSN at the same time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.248-258
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• 2020

This study proposed a breakdown structure for maintenance and management technologies under the concept of comprehensive asset management at the life cycle level of infrastructure based on benchmarking with other developed countries. For this purpose, a comparative case study was performed to review and analyze the existing definitions and hierarchies for infrastructure maintenance, repair, and rehabilitation (MR&R) systems under major industrialized countries and South Korea. In accordance with the ratio of maintenance costs to GDP, the U.S., U.K, and Japan were selected to review their systems. The classifications and definitions of MR&R technologies under the laws were analyzed. The result showed that most developed countries differentiate maintenance and repair from improvement and constitute a system centered on preventive maintenance activities. On the other hand, Korea's system for facility management is not definitely classified and still focused on reactive structures, which need to be improved. In this study, as proposed, a breakdown structure established the concept of Maintenance and Management, Maintenance & Repair, and Performance Improvement. Consequently, this study could be used as the basis for the implementation of preventive MR&R activities and reasonable resource allocations from an asset management point of view.

• Journal of the Korea Institute of Building Construction
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• v.8 no.1
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• pp.97-102
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• 2008

The report of the Korean Board of Audit and Inspection(BAI) on May 2007 indicates the problems of Life Cycle Cost (LCC) analysis and evaluation in the Design-Build(Turn-Key) and alternative bidding system. The point which the report indicates is that the cost estimation system for LCC analysis has nothing in common each other and there's no consistency among the repair cycle and ratio per facilities parts. For solving these problems, BAI demands the establishment of the guidelines for LCC analysis and evaluation from the competent authority Korean Ministry of Construction And Transportation(MOCT). The objective of this study is to develop the improvement directions for LCC analysis and evaluation which are suitable to the public construction projects especially for the Design-Build and alternative bidding system in Korea. For this study, the LCC related raws and regulations, LCC analysis guidelines of public cooperations, actual condition of LCC analysis and evaluation which include, the elements of LCC, the estimation rules of the initial cost and the maintenance cost, the analysis standards of time value of money, etc. are investigated to provide the improvement directions for LCC analysis and evaluation.

• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.637-640
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• 2006

Corrosion from various causes of reinforcing steel in concrete structures not only shortened the life of structures but also it is necessary a great repair cost to return and protect to the health condition. Using Nitrite inhibitors is a typical protection method. But there is no materials for the study about corrosion protection using nitrite. Therefore it is important to evaluate the additional rate and influence on congealment using the nitrite inhibitors in cement paste which is originally the basic material and crucial factors consisting concrete. The purpose of this study is finding influence of the type of nitrite inhibitors and mixing ratio on congealment of cement paste, and finding best corrosion inhibitors and ratio in cement paste.

• Steel and Composite Structures
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• v.45 no.2
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• pp.293-303
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• 2022

In order to improve the seismic resilience of coupled wall structure, coupling beam with fuse has been developed to reduce the post-earthquake damage. However, the fuses often have a build-up I-shaped section and are relatively heavy to be replaced. Moreover, the fuse and the beam segments are usually connected by bolts and it is time-consuming to replace the damaged fuse. For reducing the repair time and cost, a novel quickly replaceable coupling beam with buckling-restrained energy dissipaters is developed. The fuse of the proposed coupling beam consists of two chord members and bar-typed energy dissipaters placed at the corners of the fuse. In this way, the weight of the energy dissipater can be greatly reduced. The energy dissipaters and the chords are connected with hinge and it is convenient to take down the damaged energy dissipater. The influence of ratio of the length of coupling beam to the length of fuse on the seismic performance of the structure is also studied. The seismic performance of the coupled wall system with the proposed coupling beam is compared with the system with reinforced concrete coupling beams. Results indicated that the weight and post-earthquake repair cost of the proposed fuse can be reduced compared with the typical I-shaped fuse. With the increase of the ratio of the beam length to the fuse length, the interstory drift of the structure is reduced while the residual fuse chord rotation is increased.

• The Journal of Fisheries Business Administration
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• v.8 no.2
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• pp.1-19
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• 1977

The results analyzed of the actual state of medium size two-boat trawler fishery based on the cost expended in 1975 are as follows: According to the calculation of interest, the total cost of this fishery comes to ￦ 55,353,807, and in this account, the production cost comes to ￦ 49,747,383 (89.9%) and the material cost comes to ￦ 27,027,662(48.8%), the labour cost comes to ￦ 10,381,013 (18.8%) the expenses, ￦12,338,708(22.3%) and commision and interest comes to ￦ 5,606,424 (10.1%). As above the fishery comes is 90% of production cost for the expense of production. The ratio of cost element to the total cost 100 is as follow: Fuel: 23.6%, allocation: 14.3%, fishing gear: 14.1%, boat repair: 13.0%, fish box: 8.5%, ice: 14.1%, commission: 6.9%, food cost: 4.5%, interest: 3.2%, transportation fee: 2.8%, consumption: 2.6%, tax: 2.5%, depreciation: 2.4%, administrative expense: 1.6%. The unit cost of catches to each box, including the interest, cames to ￦ 2,167 and not calculating the interest it comes to ￦ 2,098. The cost production to each kg comes to ￦ 114 including interest, without interest, it comes ￦110. When the production cost comes to 90.6%, it comes to 9.4% of total revenue. The reason which this fishery brings low income is that the boats are almost old and semi-diesel engine is used. So, fuel expense and repaire expenses needs too much. Acconding to above this fishery needs to replace new boat and new engine. And new are for this fishery needs to bring under cultivation in order to bring good income with the new method for this fishery. Specially, this fishery brings low income from July to September because of its rest from labour. And so, the expenses, item, and account of money, and the trust money the cost element are not showed in August.