• Nuclear Engineering and Technology
• /
• v.54 no.10
• /
• pp.3595-3603
• /
• 2022

Nuclear safety-class DCS is used for nuclear reactor protection function, which is one of the key facilities to ensure nuclear power plant safety, the maintenance for DCS to keep system in a high reliability is significant. In this paper, Nuclear safety-class DCS system developed by the Nuclear Power Institute of China is investigated, the model of reliability estimation considering nuclear power plant emergency trip control process is carried out using Markov transfer process. According to the System-Subgroup-Module hierarchical iteration calculation, the evolution curve of failure probability is established, and the preventive maintenance optimization strategy is constructed combining reliability numerical calculation and periodic overhaul interval of nuclear power plant, which could provide a quantitative basis for the maintenance decision of DCS system.

• Journal of the Korean Data and Information Science Society
• /
• v.17 no.2
• /
• pp.367-377
• /
• 2006

This paper develops a periodic preventive maintenance(PM) policy following the expiration of warranty. Two types of warranty are considered: renewing warranty and non-renewing warranty. Also, we consider the situation where each PM cost is an increasing function of the PM effect. We determine the optimal number of PM's before replacing the system by a new one and the optimal length of period for the periodic PM following the expiration of warranty. Explicit solutions to determine the optimal periodic PM are presented for the Weibull distribution case.

• Proceedings of the Korean Statistical Society Conference
• /
• 2002.11a
• /
• pp.147-151
• /
• 2002

Burn-in is a widely used method to eliminate initial failures. Preventive maintenance policy such as block replacement with minimal repair at failure is often used in field operation. In this paper burn-in and maintenance policy are taken into consideration at the same time. The cost of a minimal repair is assumed to be a non-decreasing function of its age. The problems of determining optimal burn-in times and optimal maintenance policy are considered.

• Management Science and Financial Engineering
• /
• v.14 no.1
• /
• pp.65-86
• /
• 2008

In this paper, we have considered the multicriteria quadratic plant location problem. In addition to the allocation costs, the maintenance costs of the plants are also considered. The objective functions considered in this paper are quadratic in nature. The given problem is reduced to the problem with linear objective function. The method of Fernandez and Puerto (2003) is applied to solve the reduced problem. It is illustrated with help of examples. The effect of the change in the allocation and maintenance costs on allocation of plants to the clients has also been discussed.

• Journal of the Korean Society of Physical Medicine
• /
• v.15 no.4
• /
• pp.55-65
• /
• 2020

PURPOSE: This study examined the effects of breathing exercises via joint mobilization on the lung function and spinal alignment of 30 straight-necked women in their 20 s and 30 s. METHODS: The participants were divided into two groups: an experimental group who performed breathing exercises via joint mobilization, and a control group who performed general stretching exercises. The differences between the two groups were measured and compared at three points in time: during the pre-examination, after four weeks of intervention, and after a four-week maintenance period. The changes in each group were measured before and after the intervention and after a one-month maintenance period and compared. For data analysis, the SPSS 22 was used to obtain the mean and standard deviation with a significance level of α = .05. RESULTS: Eight weeks of breathing exercises via joint mobilization and general stretching exercises positively impacted the lung function and spinal alignment in straight-necked patients. In particular, the experimental group showed more significant differences in spinal alignment after four weeks period of intervention and four weeks of maintenance. CONCLUSION: Breathing exercises via joint mobilization can be considered an effective intervention that can improve the respiratory volume and spinal alignment for patients with straight necks.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.41 no.2
• /
• pp.24-31
• /
• 2018

As a system complexity increases and technology innovation progresses rapidly, leasing the equipment is considered as an important issue in many engineering areas. In practice, many engineering fields lease the equipment because it is an economical way to lease the equipment rather than to own the equipment. In addition, as the maintenance actions for the equipment are costly and need a specialist, the lessor is responsible for the maintenance actions in most leased contract. Hence, the lessor should establish the optimal maintenance strategy to minimize the maintenance cost. This paper proposes two periodic preventive maintenance policies for the leased equipment. The preventive maintenance action of policy 1 is performed with a periodic interval, in which their intervals are the same until the end of lease period. The other policy is to determine the periodic preventive maintenance interval minimizing total maintenance cost during the lease period. In addition, this paper presents two decision-making models to determine the preventive maintenance strategy for leased equipment based on the lessor's preference between the maintenance cost and the reliability at the end of lease period. The structural properties of the proposed decision-making model are investigated and algorithms to search the optimal maintenance policy that are satisfied by the lessor are provided. A numerical example is provided to illustrate the proposed model. The results show that a maintenance policy minimizing the maintenance cost is selected as a reasonable decision as the lease term becomes shorter. Moreover, the frequent preventive maintenance actions are performed when the minimal repair cost is higher than the preventive maintenance cost, resulting in higher maintenance cost.

• International conference on construction engineering and project management
• /
• 2009.05a
• /
• pp.310-315
• /
• 2009

Large hospitals such as medical centers provide not only medical services, but also carry the responsibilities for emergency refuges, medical researches and education. The function of large hospitals is as important as other infrastructure systems such as highways, bridges, and utilities. When disasters occur, the hospitals have to provide emergency medical services for victims and support the patient's needs of health. In order to keep a smooth operation of hospitals, the maintenance management of hospital buildings should be carefully investigated. However, there are few researches focused on maintenance management issues of hospital buildings. This paper investigated the National Taiwan University Hospital (NTUH) and established a maintenance cost database. The NTUH is the best-known and most high-renowned medical center in Taiwan in which more than 4,000 employees serving approximately 2,000 in-patients and 7,000 out-patients daily. The data were collected from the NTUH which consisted of 16,228 maintenance records in the past ten years. This paper analyzed these data to obtain various characteristics of maintenance records, and revealed the key items of maintenance cost for large hospital buildings, which can provide the facility manager of hospital buildings to execute a proper maintenance policy for hospital buildings.

• KIEAE Journal
• /
• v.16 no.3
• /
• pp.129-135
• /
• 2016

Purpose: Building figuration is imperative to perceive the its value, environmental clean status and form. Therefore, maintenance activities of the building exterior are required to keep the housing condition and value. Each household should pay the repair cost which is brought out in the future. For this repair cost, the estimation model would needed to forecast and provide the required cost. This study aimed at providing the estimation model of the repair cost, using the repair survey data between the 2011 and 2014 in Seoul. Method: For these, it took various estimation function of repair cost such as 1st function, inverse function and so on. These above functions would be applied into the building exterior and outdoor facilities which figure the building shape and characteristics. Result: Results of this study are shown ; First, among 11 estimation models, the power function has a better statistics and goodness-of-fit than any other models. Second, the estimation model with a variable of household has a pattern in upward to the right. On the contrary, the model with management area is little downward to the right. Both of them are depended on the estimated parameter of the power function and the parameter smaller than 1.

• Journal of Technology Innovation
• /
• v.5 no.1
• /
• pp.150-180
• /
• 1997

This article introduces the five functions of the national innovation system(NIS). As one of social systems in the national level, the five generic functions of open system - production, boundary spanning, maintenance, adaptation, management functions - are applied to the NIS. The production function is the primary process, which produces innovative products and services of the NIS. The boundary spanning function is the function of procuring input and disposing the innovation output or aiding in these processes. Experienced R&D human resources, R&D funds, technology etc. are some of the components of the input of the NIS. The maintenance function is responsible for maintaining smooth operation and upkeeping the system in terms of various conditions. The adaptation function is to help the system change and adapt, and scan the environment for problems, opportunites, and technological developments. It has outward orientation, from the long-term view for the survival of the system. The management function carries out planning and control of the overall activities for the other four functions in order to effectiving run the system as a whole. Finally, this article discusses implications of the diagnosis of the national innovation system and the decision making process of S&T policy.

• Communications for Statistical Applications and Methods
• /
• v.15 no.6
• /
• pp.909-923
• /
• 2008

This paper considers the replacement model and the preventive maintenance model following the expiration of combination warranty for a repairable system. If the system fails after the combination warranty is expired, then it is minimally repaired at each failure. The criterion used to determine the optimal replacement policy and the optimal preventive maintenance policy is the overall value function based on the expected cost rate per unit time and the expected downtime per unit time. The numerical examples are presented for illustrative purpose when the failure time follows a Weibull distribution.