• Magazine of the Korean Society of Agricultural Engineers
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• v.33 no.4
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• pp.105-120
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• 1991

This study was performed to investigate the minimum safety factor of embankment in consideration of seismic coefficient by the psuedo-static analysis The variables were cohesion, the internal friction angle, angle of slope, height of seepage, height of embankment, depth of replacement The results obtained were compared with those by Fellenius method, simplified Bishop method and Janbu method. The results were summarized as follows: 1.The increasing rate of the minimum safety factor with the increasing of cohesion appeared larger in Fellenius method and Bishop method than in Janbu method. And that with the increasing of the internal friction angle appeared the lowest value in Janbu method. The minimum safety factor was influenced larger on the internal friction angle than on cohesion. 2.The variation of the minimum safety factor with the height of seepage at 0m and 5 m was nearly similar to Fellenius method, Bishop method and Janbu method. On the other hand, it was decreased suddenly at 25 m. 3.The minimum safety factor with the height of embankment was decreased remarkably under 10 m with the increasing of seismic coefficient. But, it was decreased slowly more than 10 m. As the height of embankment was low, the influence of cohesion appeared larger. 4.In heigher case of the depth of replacement, the phenomenon of reduction of the minimum safety factor appeared remarkably with seismic coefficient increased. And in lower case of the depth of replacement, the minimum safety factor was similar in Fellenius method and Bishop mehtod. But it appeared larger in Bishop method and Janbu method than in Fellenius method with the depth of replacement increased. 5.As the cohesion and the internal friction angle were large, the phenomenon of reduction of the minimum safety factor with the increasing of seismic coefficient appeared remarkably. Also, the influence of seismic coefficient in minimum safety factor appeared larger with the soil parameter increased. 6.When the seismic coefficient was considerated, investigation of the structural body on the slope stability appeared profitably in Fellenius method and Janbu method than in Bishop method.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.1
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• pp.11-15
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• 2002

The present investigation was undertaken to study the effects of non-genetic factors and association among replacement and lifetime production traits. The data on 542 Holstein Friesian cows maintained during 1975-98 at State Cattle Breeding Project, Sector III, Hisar, were utilized. The average sex-ratio, abnormal births, mortality, culling and replacement rates on total calf born and total female calf born basis were 51.62, 8.50, 17.52, 31.05, 22.78 and 51.41 per cent, respectively. The study revealed that a minimum of 4 to 5 progenies are required per cow over its lifetime to replace itself. It indicated that each cow should produce a minimum of 2 female calves during its life so as to replace herself before being lost. The least-squares means for productive herd life, longevity and lifetime production were $1439.32{\pm}87.64$ and $2419.18{\pm}8.25$ days and $11317.95{\pm}913.15kg$, respectively. The heritability estimates for all replacement traits were very low indicating that sire selection may bring no desirable change in these traits. Heritability estimates were $0.178{\pm}0.157$, $0.288{\pm}0.184$ and $0.096{\pm}0.195$ for corresponding lifetime production traits. Breeding values and ranking of sires were generated for replacement and lifetime production traits to estimate the rank correlations between these traits. Moderate desirable rank correlations were obtained between replacement rate and lifetime production traits indicating that sires proven on the basis of milk production are also expected to have better replacement rate.

• Journal of the Korean Geotechnical Society
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• v.29 no.11
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• pp.29-47
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• 2013

This study undertook research on the sections of 90 harbor structures which applied a pile-type soil improvement using the soil-cement pile and then, determined the minimum replacement rate for each section, showing sufficient stability in all relevant studies including numerical analysis. The reliability of the numerical analysis was verified by a centrifuge model test. As a result of the study, it was revealed that when the foundation soil is too soft ($s_u$ = under 15 kPa), it is unsuitable to apply a pile-type ground improvement to a soil improvement regardless of types of super structures. And a pile-type soil improvement was found to be suitable for a harbor structure with the relative stiffness ratio (n) of less than 50~75 at a maximum and the 2~3 MPa strength of the soil-cement pile. Furthermore the governing factor for the minimum replacement rate for the pile-type soil improvement was turned out to be the allowable horizontal displacement. Therefore, the primary review to see the applicability of the pile-type soil improvement requires the evaluation of horizontal displacements.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.189-190
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• 2023

Environmental pollution problems are occurring in Jeju Island due to negative treatment of basalt waste. Measures for various approaches and utilization measures are needed to solve the problem of waste stones that occur during basalt processing. In this study, the Properties of permeable blocks with basalt were identified and the applicability and functionality as building materials were reviewed. This experiment is basic data for evaluating the functionality of the permeable block by manufacturing permeable blocks using basalt waste stones and analyzing flexural strength and compressive strength. The higher the basalt waste stone replacement rate, the lower the flexural strength and compressive strength, but it was judged that 20% of basalt waste stone replacement rate that satisfies the minimum flexural strength (4.0MPa) stipulated in KS F 4419 was appropriate. In addition, additional permeability coefficient and absorption rate experiments tended to increase as the basalt lung stone replacement rate increased. Therefore, it is judged that the permeable block using basalt waste stone is superior to the existing permeable block.

• Journal of the Korea Society for Simulation
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• v.33 no.1
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• pp.27-34
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• 2024

This study aims to propose an optimal asset allocation that minimizes the risk of insufficient realized replacement rates compared to the OECD average replacement rate. To do this, we set the shortfall risk of replacement rates and calculates an asset allocation plan to minimize this risk based on the period of enrollment, the income level and additional contribution. We consider stocks and deposits as investment assets, using Monte Carlo simulation with a GBM model to generate return distributions for stocks. Our result show that, for individuals with a enrollment period of less than 30 years, participants should invest a minimum of 70-80% of their funds in risky assets to minimize the shortfall risk. However, the proportion of funds that need to be invested in risky assets declines significantly when participants contribute an additional premiums. This effect is particularly pronounced among low-income individuals. Therefore, to achieve OECD average replacement rates, the government needs to incentivize participants to invest more in risky assets, while also providing policies to encourage additional contributions, especially for the low-income population.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.1
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• pp.61-69
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• 2020

Systems such as database and socal network systems have been broadly used, and their unexpected failure, with great losses and sometimes a social confusion, has received attention in recent years. Therefore, it is an important issue to find optimal maintenance plans for such kind of systems from the points of system reliability and maintaining cost. However, it is difficult to maintain a system during its working cycle, since stopping works might incur users some troubles. From the above viewpoint, this paper discusses minimal repair maintenance policy with periodic replacement, while considering the random working cycles. The random working cycle and periodic replacement policies with minimal repair has been discussed in traditional literatures by usually analyzing cases for the nonstopping works. However, maintenance can be more conveniently done at discrete time and even during the working cycle in real applications. So, we propose that periodic replacement is planned at discrete times while considering the random working cycle, and moreover provide a model in which system, with a minimal repair at failures between replacements, is replaced at the minimum of discrete times KT and random cycles Y. The average cost rate model is used to determine the optimal number of periodic replacement.

• Journal of Korean Foot and Ankle Society
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• v.18 no.4
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• pp.195-201
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• 2014

Purpose: The purpose of this study is to develop guidelines for clinical trial of the total ankle replacement system for premarket approval. Materials and Methods: We selected and analyzed nine peer-reviewed articles whose quality had been proven in a previous phase. Two investigators extracted parameters for guideline criteria, including number of cases, patient age, follow-up period, failure rate, radiographic osteolysis rate, residual pain rate, and percentage of satisfaction. In addition, the inclusion and exclusion criteria were analyzed and developed. Results: Eight level IV studies and one level II study were included. The average number of cases was 159 cases and the mean patient age was 63.5 years. The mean follow-up period was 4.2 years, ranging from two to nine. The average failure rate of total ankle replacement in mid- to long-term follow-up was approximately 13% (2%~32.3%). The rate of osteolysis was approximately 18%. Residual pain was common (21.4%~46%), but overall patient satisfaction was approximately 85.6% (67.5%~97%). Conclusion: The results could be used as criteria for designing the clinical studies, such as number of cases, patient age (over 60 years), and follow-up period (minimum two years). The clinical scoring system and 36-item short form health survey (SF-36) was the most commonly used method for clinical evaluation for total ankle arthroplasty. In addition, the overall results, including failure rate, osteolysis rate, and patient satisfaction, could be used as a parameter of guidelines for premarket approval.

• Journal of Construction Engineering and Project Management
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• v.1 no.3
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• pp.28-37
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• 2011

Domestic construction companies are suffering from financing difficulties in the wake of the economic slump in Korea and abroad. During this economic slump, real estate investment trusts (REITs), facilitators for improving financing and stimulating construction businesses, have increasingly expanded since their introduction in 2001. However, in terms of growth speed and marketing size, Korean REITs are falling behind those of other nations. The purpose of this study is to suggest a method for composing a portfolio using the Markowitz portfolio selection model to stimulate REITs. The main contents are as follows. First, a comparative analysis was conducted of increased REIT profit with the application of the Markowitz model and the average REIT profit rate from July 3, 2007, to July 21, 2008, during the investment analysis periods. The results showed that the total profit rate from the Markowitz model was about 10% higher than the average REIT profit rate. Second, the sensitivity was analyzed according to the portfolio's data-gathering and replacement cycle to measure the optimum cycle and yield. The six-mouth profit data collection period showed about 16% higher profits with the Markowitz model than with the REITs. The two-week portfolio change period resulted in about 11% higher profits with the Markowitz model than with the REITs.

• Clean Technology
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• v.12 no.4
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• pp.238-243
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• 2006

The aggregate properties of chilled converter slag reformed by atomizing liquid converter slag were investigated. The properties of mortars with various replacement of standard sand by chilled converter slag as recycled fine aggregates were investigated. The particle shape of chilled converter slag by atomizing was a sphere with an open cavity which is enclosed with two layers like a bored coconut. Specific gravity, unit weight and fineness modulus increased with increasing the replacement, and solid content had the maximum at the replacement of 75% and water absorption rate had the minimum at the replacement. The hardened mortars with higher replacements have the higher specific gravity and the denser texture.

• 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.