• Asian-Australasian Journal of Animal Sciences
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• v.13 no.12
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• pp.1691-1698
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• 2000

An in situ digestion trial (Experiment 1) and a lactation trial (Experiment 2) were conducted to determine the effects of replacing corn and wheat bran with soyhulls (SH) in lactating dairy cow diets on the extent and kinetics of digestion of DM and NDF, and lactation performance. In experiment 1, five mixed feeds consisting of mixed concentrate and roughages (50:50 on a DM basis) were formulated on isonitrogenous and isoenergetic bases to produce five levels (0, 25, 50, 75 and 100%) of SH replacement for corn and wheat bran. SH had high in situ digestion (92 and 89% for potentially digestible DM and NDF) and fairly fast digestion rate (7.2 and 6.3 %/h for DM and NDF). Increasing level of SH replacement resulted in increased NDF digestibility (linear, p=0.001-0.04) and similar DM digestibility (beyond 12 h incubation, p=0.10-0.41). As level of SH replacement increased, percentage of slowly digestible fraction (b) of DM increased (linear, p=0.03), percentage of rapidly digestible fraction (a) of DM tended to decrease (linear, p=0.14), and DM digestion lag time tended to be longer (linear, p=0.13). Percentage of potentially digestible fraction (a+b) and digestion rate (c) of slowly digestible fraction of dietary DM remained unaltered (p=0.36-0.90) with increasing SH in the diet. Increasing level of SH for replacing corn and wheat bran in the diet resulted in increases in percentages of b (quadratic, p<0.001), a (linear, p=0.08), a+b (quadratic, p=0.001) and a tendency to increase in c for NDF (linear, p<0.19). It was also observed that there was a satisfactory fit of a non-linear regression model to NDF digestion data ($R^2=0.986-0.998$), but a relatively poor fit of the model to DM digestion data ($R^2=0.915-0.968$). In experiment 2, 42 lactating Holstein cows were used in a randomized complete block design. SH replaced corn and wheat bran in mixed concentrates at 0, 25, and 50%, respectively. These mixed concentrates were mixed with roughages and fed ad libitum as complete diets. Replacing corn and wheat bran with SH at 0, 25 and 50% levels did not influence (p=0.56-0.95) DM intakes (18.4, 18.6, and 18.5 kg/d), milk yields (27.7, 28.4 and 27.6 kg/d), 4% fat-corrected-milk (FCM) yields (26.2, 27.6, and 27.3 kg/d) and percentages of milk protein (3.12, 3.17 and 3.18%), milk lactose (4.69, 4.76 and 4.68%) and SNF (8.50, 8.64, and 8.54%). On the other hand, milk fat percentges linearly increased (3.63, 3.85 and 3.90% for SH replacement rates of 0, 25 and 50% in the diet, p=0.08), while feed costs per kg FCM production were reduced.

• Journal of Korea Water Resources Association
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• v.42 no.7
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• pp.525-535
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• 2009

In this paper a heuristic method for identifying individual pipes in water pipe networks to determine specific sections of the pipes that need to be replaced due to deterioration. An appropriate minimum pipe length is determined by selecting the pipe length that has the greatest variance of the average cumulative break number slopes among the various pipe lengths used. As a result, the minimum pipe length for the case study water network is determined as 4 m and a total of 39 individual pipe IDs are obtained. The economically optimal replacement times of the individual pipe IDs are estimated by using the threshold break rate of an individual pipe ID and the pipe break trends models for which the General Pipe Break Prediction Model(Park and Loganathan, 2002) that can incorporate the linear, exponential, and in-between of the linear and exponetial failure trends and the ROCOFs based on the modified time scale(Park et al., 2007) are used. The maximum log-likelihoods of the log-linear ROCOF and Weibull ROCOF estimated for the break data of a pipe are compared and the ROCOF that has a greater likelihood is selected for the pipe of interest. The effects of the social costs of a pipe break on the optimal replacement time are also discussed.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.3
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• pp.63-72
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• 2010

This study was conducted to investigate the current status and the improvement plans of the ecosystem conservation fund return projects. In 2007, there was a reformation of the ecosystem conservation fund system but the fund return projects were not vitalized up until now. In this study, 35 of ongoing and finished fund return projects were investigated on their types, sites, costs, local governments, and time required to return the fund. Through the on-site survey of 9 finished projects (4 biotope, 2 corridor and 3 natural conservation facility projects), construction and management conditions were investigated. The main findings are as follows: Among the five fund return types, 17 cases were biotope restoration projects, 4 cases were ecological corridor projects, and 1 case was a nature replacement project. In the case of project sites, there were 14 cases near schools and public facilities, 8 cases near rivers or streams, and 2 cases near ponds or wetlands. For the construction costs, there were 19 cases (65% of all the projects) that cost less than 300 million won. In terms of the involvement of the local government, most of the fund return projects were concentrated in Gyeonggi province and Ulsan city, and there were some local governments outside of these regions that did not carry out any return projects at all. Lastly, in the case of fund return time required, 35% of the fund returns were completed within 5 months, but the overall average fund return time was 9.8 months. In respond to the above study results, the improvement plans to encourage fund return projects are as follows: To diversify return types and sites, piloting and modeling projects for the representative types and sites should be preceded. To emerge from customary small-scaled projects, incentives to encourage large-scale and ecological networking projects should be considered. In addition, in order to write up business plans for the fund return projects, long-term investigations of at least 2 seasons from spring to fall are necessary. Finally, for the continuous management and maintenance of the ecological fund return sites, easier way for the citizens to actively participate in the projects should be incorporated.

• Journal of Korean Society of Steel Construction
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• v.17 no.2 s.75
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• pp.227-241
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• 2005

This paper presents a practical and realistic Life-Cycle Cost (LCC) optimum design methodology for steel bridges considering the long-term effect of environmental stressors such as corrosion and heavy truck traffics on bridge reliability. The LCC functions considered in the LCC optimization consist of initial cost, expected life-cycle maintenance cost, and expected life-cycle rehabilitation costs including repair/replacement costs, loss of contents or fatality and injury losses, road user costs, and indirect socio-economic losses. For the assessment of the life-cycle rehabilitation costs, the annual probability of failure, which depends upon the prior and updated load and resistance histories, should be accounted for. For the purpose, Nowak live load model and a modified corrosion propagation model, which takes into consideration corrosion initiation, corrosion rate, and repainting effect, are adopted in this study. The proposed methodology is applied to the LCC optimum design problem of an actual steel box girder bridge with 3 continuous spans (40m+50m+40m=130m). Various sensitivity analyses are performed to investigate the effects of various design parameters and conditions on the LCC-effectiveness. From the numerical investigation, it has been observed that local corrosion environments and the volume of truck traffic significantly influence the LCC-effective optimum design of steel bridges. Thus, these conditions should be considered as crucial parameters for the optimum LCC-effective design.

• Journal of the Korea Institute of Building Construction
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• v.22 no.4
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• pp.403-414
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• 2022

Many studies have been conducted on asset management of public facilities, as the importance of such management has been increasing. This basic study aims to present strategies for the practical use of public asset management, and seeks to propose efficient management and utilization measures from a cost perspective by comparing and analyzing the importance and impact relationship between cost items for public asset management. In this study, 19 sub-items and the top 4 items were chosen by deriving cost factors based on the previous literature. A survey was conducted, and the results of the survey were analyzed by using the Analytic Hierarchy Process(AHP) and Interpretive Structural Modeling (ISM) methods. The AHP was used to derive the priority between items, and ISM was used to identify major groups and mutual influences. As a result, those items showing both high priority and high importance, such as user cost, dismantling/disposal cost, replacement cost, maintenance/repair cost, etc. are determined as priority items to be considered for public asset management of public facilities. Also, it is necessary to minimize the impact on other items in public asset management by those items which are impacted less by other items but have significant impact on the items such as initial construction costs, conceptual design costs, construction costs, and supervision costs. It is expected that the results and analysis methods presented in this study can be used to provide strategies for asset management of public facilities.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.75-89
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• 2006

This paper presents a practical and realistic Life-Cycle Cost (LCC) optimum design methodology of steel bridges considering time effect of bridge reliability under environmental stressors such as corrosion and heavy truck traffics. The LCC functions considered in the LCC optimization consist of initial cost, expected life-cycle maintenance cost and expected life-cycle rehabilitation costs including repair/replacement costs, loss of contents or fatality and injury losses, road user costs, and indirect socio-economic losses. For the assessment of the life-cycle rehabilitation costs, the annual probability of failure which depends upon the prior and updated load and resistance histories should be accounted for. For the purpose, Nowak live load model and a modified corrosion propagation model considering corrosion initiation, corrosion rate, and repainting effect are adopted in this study. The proposed methodology is applied to the LCC optimum design problem of an actual steel box girder bridge with 3 continuous spans (40 m+50 m+40 m=130 m), and various sensitivity analyses of types of steel, local corrosion environments, average daily traffic volume, and discount rates are performed to investigate the effects of various design parameters and conditions on the LCC-effectiveness. From the numerical investigation, it has been observed that local corrosion environments and the number of truck traffics significantly influence the LCC-effective optimum design of steel bridges, and thus realized that these conditions should be considered as crucial parameters for the optimum LCC-effective design.

• Annals of Occupational and Environmental Medicine
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• v.34
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• pp.3.1-3.12
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• 2022

Background: Influenza illness causes several disruptions to the workforce. The absenteeism that often ensues has economic implications for employers. This study aimed to estimate the cost-benefit of influenza vaccination in a healthcare setting from the employer's perspective. Methods: A cross-sectional questionnaire survey was conducted in a private hospital in 2018-2019 comparing voluntary vaccinated with non-vaccinated employees with influenza vaccine. The analyses were made based on self-reporting on absenteeism and presenteeism from Influenza-like illnesses (ILIs). The costs incurred, both direct and indirect costs, were included in the study. A cost-benefit analysis was performed by measuring the cost of the vaccination program. The costs of absenteeism and reduced productivity were calculated using 3 hypothesised levels of effectiveness in the following percentage of productivity of 30%, 50%, and 70%. The costs were also calculated based on four scenarios: with and without operating income and with and without replacement. The benefits of the influenza vaccination from the employer's perspective were analysed. The benefit to cost ratio was determined. Results: A total of four hundred and twenty-one respondents participated. The influenza vaccination rate was 63.0%. The rate of ILI of 38.1% was significantly lower among vaccinated. The ILI-related absenteeism reported was also significantly lower amongst vaccinated employees at 30% compared to 70% non-vaccinated. Employers could save up to USD 18.95 per vaccinated employee when only labour cost was included or 54.0% of cost savings. The cost-saving rose to USD 155.56 when the operating income per employee was also included. The benefit to cost ratio confirmed that the net cost-benefit gained from the vaccination was more than the net cost of vaccination. Conclusions: Influenza vaccination for working adults was cost-saving and cost-beneficial when translated into financial investments for the employer. A workplace vaccination demonstrates a significant cost-benefit strategy to be applied in any institutional setting.

• The Journal of the Korea Contents Association
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• v.4 no.3
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• pp.71-80
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• 2004

In distributed file-systems, cooperative caching algorithm which owns the data cached at each node jointly is used to reduce an expense of disk access. Cooperative caching algorithm is the method that increases a cache hit-ratio and decrease a disk access as it holds the cache information of distributed systems in common and makes cache larger virtually. Recently, several cooperative caching algorithms decrease the message costs by using approximate information of the cache and increase the cache hit-ratio by using local and global cache fields dynamically. And they have an advantage that increases the whole field hit-ratio by sending a replaced buffer to the idle node on buffers replacement in order to maintain the replaced cache in the cache field. However the wrong approximate information deteriorates the performance, the consistency maintenance goes to great expense to exchange messages and the cost that manages Age-information of each node to choose the idle node increases. In this thesis, we propose a cooperative cache algorithm that maintains correct cache information, minimizes the maintenance cost for consistency and the management cost for buffer Age-information. Also, we show the superiority of our algorithm through the performance evaluation.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.2
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• pp.185-196
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• 2020

Low-pressure sodium lamps, high-pressure sodium lamps and fluorescent lamps etc are mainly used tunnel lighting in Rep. of Korea. Power rates for tunnel lighting are known to account for the highest percentage in the tunnel maintenance costs. Therefore, tunnel lights are being replaced by LED that have advantages such as low power consumption and longevity. To analysis effect of replacement low pressure sodium lamp with LED, illumination and monthly power usage for a year are investigated for 8 tunnels. Power usage for tunnel lighting is decreased by 26.1% to 59.6%, and illumination is increased by 34.1% to 293% replacing low pressure sodium lamp with LED.

• Advances in concrete construction
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• v.8 no.3
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• pp.225-237
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• 2019

Although applying self-consolidating concrete (SCC) in many modern structures is an inevitable fact, the high consumption of cement in its mixing designs has led to increased production costs and adverse environmental effects. In order to find economically viable sources with environmentally friendly features, natural pozzolan pumice and blast furnace slag in 10-50% of replacement binary designs have been investigated for experiments on the properties of fresh concrete, mechanical properties, and durability. As a natural pozzolan, pumice does not require advanced equipment to prepare for consumption and only needs to be powdered. Pumice has been the main focus of this research because of simple preparation. Also to validate the results, in addition to the control specimens of each design, fly ash as a known powder has been evaluated. Moreover, ternary mixes of pumice and silica fume were investigated to enhance the obtained results of binary mixes. It was concluded that pumice and slag powders indicated favorable performance in the high percentage of replacement.