• Journal of Korean Society for Quality Management
• /
• v.30 no.4
• /
• pp.94-105
• /
• 2002

In this paper, replacement problems for a deteriorating system are considered. In the system under consideration, the successive lifetimes after repair become shorter and shorter, while the consecutive repair times become longer and longer. More specifically, the lifetimes of the system form a nonhomogeneous Poisson process, whereas the consecutive repair times constitute a stochastically increasing geometric process. Optimal replacement policies for the long-run average cost rate and the steady state availability are considered. Also taking the cost and the availability into consideration at the same time, the properties of optimal policies under the Cost Priority Policy and the Availability Priority Policy are obtained.

• Journal of the military operations research society of Korea
• /
• v.30 no.2
• /
• pp.96-107
• /
• 2004

This paper deals with $\ulcorner$Requirement Decision Model for Repair Parts supplied by the Government$\lrcorner$ which is to reduce Aircraft Contract Maintenance Cost. It aims to find solutions to the fundamental problems of the Aircraft Contract Maintenance System. Under the current Aircraft Contract Maintenance System, it is hard to forecast the exact demand of repair parts, so support rate of Repair Parts supplied by the Government is restricted under 50 percent. It is inevitable to purchase Repair Parts from the firm with much higher price than those of Government source. However, absence of fixed demand pattern makes it difficult to improve accuracy of demand forecast. As a solution to these problems, this model prevents a cost increase due to the unit price difference between Repair Parts supplied by the Government and Repair Parts purchased by the Firm. It also reflects demand characteristics of each repair part, and prevents continual stock increase by setting an upper limit on the amount of Repair Parts supplied by the Government. The effectiveness of this model is verified by empirical analysis using the latest raw data. By applying this model to real situation, we expect to reduce about 4 billion won every year.

• Corrosion Science and Technology
• /
• v.7 no.1
• /
• pp.6-12
• /
• 2008

Non-metallic composite overwrap repair methods utilize resin based fiber-reinforced composite materials, which have higher specific strength to weight ratio and stiffness, superior corrosion and fatigue resistance, and substantially reduced weight when compared to carbon steel. Non-metallic repair methods/systems can allow desired functional properties to be achieved at a respectable economic advantage. For example, non-metallic composite repair systems have at least a 50 year design stress of 20 ksi and approximately 25% of the short term tensile strength of fiberglass. For these systems, the contribution of the repaired steel to the load carrying capability need not be considered, as the strength of the repair itself is sufficient to carry the internal pressure. Worldwide experience in the Oil & Gas industry confirms the integrity, durability, inherent permanency, and cost-effectiveness of non-metallic composite repair or rehabilitation systems. A case study of a recent application of a composite repair system in Saudi Aramco resulted in savings of 37% for offshore subsea line and 75% for onshore above grade pipeline job. Maintaining a pipeline can be costly but it is very small in comparison to the cost of a failure. Pipeline proponents must balance maintenance costs with pipeline integrity. The purpose is not just to save money but also to attain a level of safety that is acceptable. This technology involves the use of an epoxy polymer resin based, fiber-reinforced composite sleeve system for rehabilitation and /or repair pipelines.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• 2006.11a
• /
• pp.638-641
• /
• 2006

In this paper, A calculating cost method of maintenance and repair for bridge which is built up by new construction technique named Up-Down Precast Concrete(UDPSC). After 2000, 109 Bridges which are using UDPSC technique have been built up, 37 bridges's construction work are processing, and 194 designs are presented for construction. Because this technology has developed recently, there are few field data for analyzing the maintenance and repair cost. Therefore, the maintenance and repair cost is computed using Construction and Transportation Ministry's guide line for computation and former research's data.

• Journal of the Korean Society of Safety
• /
• v.25 no.6
• /
• pp.115-122
• /
• 2010

The importance of the life cycle cost (LCC) analysis for bridges has been recognized over the last decade. However, it is difficult to predict LCC precisely since the costs occurring throughout the service life of the bridge depend on various parameters such as design, construction, maintenance, and environmental conditions. This paper presents a methodology for the optimal life cycle cost design of a bridge. Total LCC for the service life is calculated as the sum of initial cost, damage cost, maintenance cost, repair and rehabilitation cost, user cost, and disposal cost. The optimization method is applied to design of a bridge structure with minimal cost, in which the objective function is set to LCC and constraints are formulated on the basis of Korean Bridge Design Code. Initial cost is calculated based on standard costs of the Korea Construction Price Index and damage cost on damage probabilities to consider the uncertainty of load and resistance. Repair and rehabilitation cost is determined using load carrying capacity curves and user cost includes traffic operation costs and time delay costs. The optimal life cycle cost design of a bridge is performed and the effects of parameters are investigated.

• Journal of the Korean housing association
• /
• v.17 no.4
• /
• pp.65-72
• /
• 2006

Most of buildings have been deteriorated with time-elapse by reflection of the building location, material, environmental circumstances and so on. The performance would go down and be demolished if anything could not be done after constructed. The maintenance should be required to preserve a decent living condition or improve a inferior condition by various plans and practices. The maintenance plan needs various data such as a repair scope, a repair time, a forecasted cost, a plan of management and so forth. Among the above required data for planning the maintenance, the deterioration characteristics of the building components would be first analyzed. The deterioration pattern would be a key role to affect and make a maintenance plan. In this paper, it aimed at classifying the deterioration patterns of building components. A deterioration pattern would be analyzed between the cumulative repair cost and time-elapse and modeled with these relations. A deterioration patterns are classified into 4 types-a accelerated type, a straight type, a temporary type and a slowly type. As a result of this research, a accelerated type includes window, window frame, general paintings, general water proofing in building components. A straight type includes the lacquer paintings, furnishings in building components and water supply pipe, boiler, sanitaries in mechanical facilities and lighting in electric facilities. Based on these research results, further study should be conducted to include any other components and an estimating model.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.18 no.1
• /
• pp.99-104
• /
• 2010

It is a frequent occurrence in urban traffic - a low-speed collision in which one vehicle hits the back of another. The vehicles often sustain expensive damage. Bumpers can reduce this damage, but only line up so the initial contact in an impact is bumper to bumper. Then the bumpers on the colliding vehicles have to absorb the crash energy, keeping damage away from expensive sheet metal, lights, and other components. In real world accidents, Bumper mismatches in crashes are increasing, and the resulting repair costs from low-speed collisions are escalating. In this study, we investigated the bumper rail height and analyzed their effects on repair cost. Futhermore, Our 16kph front-into-rear crash tests demonstrates bumper mismatch problem.

• International Journal of Highway Engineering
• /
• v.18 no.3
• /
• pp.11-19
• /
• 2016

PURPOSES : This study supports the evidence that it is possible to rehabilitate a damaged pavement with a lane closure specifically based on the Gimcheon~Sunsan project. METHODS : The prediction results from the simulation programs were compared with field monitoring, which focused on traffic management planning, congestion (length, time, and passing speed), bypass, and user cost, among others. RESULTS : The research results showed that lane closure application and pavement repair of the aged pavement in Korea were possible, even though the prediction results were minimally different from the field monitoring. The road agency contributes to service life extension of the rehabilitated pavement using this method. CONCLUSIONS : A marginal effect caused by the lane closure was observed on travelling users or vehicles, and the user cost of pavement repair decreased. Therefore, introducing the repair method or rehabilitation in Korea is possible. Information dissemination through various media was properly done to execute the project well. Moreover, the construction area traffic utilized nearby alternative roads. Therefore, improving the repaired pavemen's service life while ensuring that the pavement management agency can provide a road with comfortable user riding quality was possible.

• Journal of the Korea Safety Management & Science
• /
• v.6 no.1
• /
• pp.61-70
• /
• 2004

In this paper, a group replacement policy based on a failure count is analysed. For a group of identical repairable units, a maintenance policy is performed with two phase considerations: a repair interval phase and a waiting interval phase. Each unit undergoes minimal repair at failure during the repair interval. Beyond the interval, no repair is made until a number of failures. The expected cost rate expressions under the policy is derived. A method to obtain the optimal values of decision variables are explored. Numerical examples are given to demonstrate the results.

• Communications for Statistical Applications and Methods
• /
• v.8 no.3
• /
• pp.711-717
• /
• 2001

Two imperfect repair models for system are considered, one introduced by Brown and Proschan(1983) and the other by Lee and Seoh(1999). We, in this paper, after assigning repair costs to the system, optimize both repair models, when the underlying life distributions of the system are exponential, uniform and Weibull.