• Journal of Korea Water Resources Association
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• v.37 no.3
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• pp.207-217
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• 2004

Our government is interested in the rehabilitation for the old sewer rather than the construction of a new sewer system. However, the research work on the sewer rehabilitation is not sufficient as much as the interest on the rehabilitation is increased. There are some research works for the determination of rehabilitation time by the genetic algorithm in Korea and foreign countries. However, the previous studies have considered the simple elements for the determination of the rehabilitation time and so the complex decision-making according to the degree of sewer superannuation has not been performed. Therefore, in this study, we estimate the capacity and Ⅰ/Ⅰ of sewer and determine the priority of the optimal rehabilitation for each outfall within the draining system. Also we develop the optimal rehabilitation decision making system for the cost estimation of optimal rehabilitation using the genetic algorithm.

• Proceedings of the Korea Water Resources Association Conference
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• 2002.05a
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• pp.425-430
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• 2002

• Journal of Korea Water Resources Association
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• v.36 no.1
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• pp.45-59
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• 2003

The method in this study, which is more efficiency than the existing method, propose the optimal rehabilitation model based on the deterioration prediction of the laying pipe by using the deterioration survey method of the water distribution system. The deterioration prediction model divides the deterioration degree of each pipe into 5 degree by using the probabilistic neural network. Also, the optimal residual durability is estimated by the calculated deterioration degree in each pipe and pipe diameter. The optimal rehabilitation model by integer programming base on the shortest path can calculate a time and cost of maintenance, rehabilitation, and replacement. Also, the model is divided into budget constraint and no budget constraint. Consequently, the model proposed by the study can be utilized as the quantitative method for the management of the water distribution system.

• Journal of Korea Water Resources Association
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• v.36 no.1
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• pp.61-74
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• 2003

This study(II) apply to the A city by using the optimal rehabilitation model based on the deterioration prediction of the water distribution system proposed the study(I). The deterioration prediction model divides factors into 14 factors with digging and experiment and 9 factor without digging and experiment and calculate the deterioration degree. The application results of the deterioration prediction model show that a difference of the deterioration degree according to factor numbers is within 1~2%. Also, the model can predict the deterioration degree of each pipe without digging and experiment. The optimal rehabilitation model is divided into the optimal residual durability of each deterioration factor and budget constraint or not. The application result is as follow: the rehabilitation time and cost increase according to the increasing of the optimal residual durability. When compared the model with budget constraint and model without budget constraint, the former model increase the cost of total contents. In case of budget constraint, the increasing tendency is concluded that the pipe rehabilitation is executed in same budget every year in condition that every rehabilitation cost do not exceed the every year budget within the optimal residual durability.

• Korean Journal of Poultry Science
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• v.10 no.2
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• pp.75-81
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• 1983

The records on 787 white Leghorn hens from two different strains, A and K were wed in this study to find out the pattern of increase in egg weight with age and the optimum age of early selection for maximizing the genetic gain. The pattern of increase in egg weight with age in two lines which was expressed on graph showed that the amount of increase was larger in the early part of the laying year and it decreased gradually. Regression equations suggested that egg weight increased linearly with age at the rate of 0.46 gram per week for line A and 0.83 gram for line K. And in the regression analyses of each period mean egg weight on annual mean egg weight, the coefficients of EW 30 that is mean egg weight from 29 weeks of age to 32 weeks of age were 0.86 for line A, 0.88 for line K, and those were the highest figures among the all regression coefficients of each mean egg weight on annual mean egg weight. In estimating the relative selection efficiency of each period mean egg weight on annual mean egg weight in EW 46, selection on EW 34 for line A and on EW 30 for line K was the most efficient for improving egg weight. These results suggested that one periods from 29 weeks of age to 36 weeks of age could be used for the best predictable time for improving annual mean egg weight.

• 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 Korean Society of Water and Wastewater
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• v.32 no.1
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• pp.37-45
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• 2018

This study develops a model to estimate the economic life of the large-diameter water supply pipeline in Korea by supplementing existing methods used to perform similar calculations. To evaluate the developed methodology, the model was applied to the actual target area with the conveyance pipe in P waterworks. The application yielded an economic life computation of 39.7 years, considering the cost of damages, maintenance, and renewal of the pipeline. Based on a sensitivity analysis of the derived results, the most important factor influencing the economic life expectancy was the predicted failure rate. The methodology for estimating the economic life of the water supply pipeline proposed in this study is one of the core processes of basic waterworks facility management planning. Therefore, the methods and results proposed in this study may be applied to asset management planning for water service providers.

• Water for future
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• v.29 no.3
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• pp.197-205
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• 1996

Flow carrying capacity of water distribution systems is getting reduced by deterioration of pipes in the systems. The objective of this study is to develop a managerial decision-making model for the rehabilitation of water distribution systems with a minimum cost. The decisions made by the model also satisfy the requirements for the discharge and pressure at demanding nodes in the system. The replacement cost, pipe break repair cost, and pumping cost are considered in the economic evaluation of the decision along with the break ratio and interest ratio to determine the optimal replacement time for each pipe. Then, the hydraulic integrity of the water distribution system is checked for the decision by a pipe network simulator, KYPIPE, if the discharge and pressure requirements, the decision made for the optimal replacement time is revised until the requirements are satisfied. The model is applied to an existing water distribution system, the Metropolita Water Supply Project (1st Phase). The result shows that the decisions for the replacement time determined by the economix analysis are accepted as optimal and the hydraulic integrity of the system is in good condition.

• KSBB Journal
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• v.9 no.2
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• pp.191-199
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• 1994

Protoplasts of both strains were produced by lysozyme digestion at $30^{\circ}C$ for 180min. Both strains were treated with $40{\mu}g$/ml of lysozyme in 30mM Tris-HCl buffer(pH 7.5) containing 10% sucrose at the late logarithmic growth phase. It was found that the efficiency of protoplast formation was high at $30^{\circ}C$ and pH 7.5 by measuring the decrease in absorbance. Optimum concentrations of sucrose $Ca^{2+}, \;Mg^{2+}$ for protoplast formation were determined to be 15%, 20mM and 6mM, respectively. Hydrolysis of cell wall and protoplast formation efficiency for L. plantarum showed better results than those for Leu. mesenteroides. The resistances to antibiotics erythromycin and chloramphenicols were chosen as the selection marker for the fusant between L. plantarum and Leu. mesenteroides. Production phase of protoplast in Leu. mesenteroides was also compared with L. plantarum in this paper.

• Korean Journal of Organic Agriculture
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• v.20 no.3
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• pp.369-383
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• 2012

This experiment was carried out to investigate the optimal stocking rate of earthworm populations grown under different stocking rates. The stocking rate in terms of ratio of biomass of earthworms to biomass of feeds(organic resources) is an important factors for biomass productivity of earthworms and vermicast production. The different stocking rates were 1:16(S-1), 1:32(S-2), 1:48(S-3) and 1:64(S-4), as the ratios of biomass of earthworm to biomass of organic dairy cow manure, respectively. The stocking rate of 1:32(S-2) and 1:46(S-3) were obtained a higher values on increasing rates and conversion efficiency of organic matter to earthworm biomass than other stocking rates. Thus, a stocking rates of 1:32 and 1:46 estimated an optimal stocking rates for maximum biomass productivity of earthworms. A stocking rate of 1:16(S-1) showed a significantly highest values of vermicast production and ratios of vermicasts during the rearing periods.($$P{\leq_-}0.05$$) A stocking rate of 1:48(S-3) showed a highest values of the number of cocoons and vermicasts production per earthworm biomass among the treatment ($$P{\leq_-}0.05$$) The contents of nitrogen, available phosphorus, cation exchange capacity and exchangeable cations of vermicasts tended to increase with stocking rate and rearing progressed. Vermicasts have a great deal of potential for crop production and protection in sustainable organic cropping systems.