• 한국공간구조학회논문집
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• 제23권2호
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• pp.79-90
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• 2023

Existing reinforced concrete (RC) frame buildings have seismic vulnerabilities because of seismically deficient details. In particular, since cumulative damage caused by successive earthquakes causes serious damage, repair/retrofit rehabilitation studies for successive earthquakes are needed. This study investigates the repair effect of fiber-reinforced polymer jacketing system for the seismically-vulnerable building structures under successive earthquakes. The repair modeling method developed and validated from the previous study was implemented to the building models. Additionally, the main parameters of the FRP jacketing system were selected as the number of FRP layers associated with the confinement effects and the installation location. To define the repair effects of the FRP jacketing system with the main parameters, this study conducted nonlinear time-history analyses for the building structural models with the various repairing scenarios. Based on this investigation, the repair effects of the damaged building structures were significantly affected by the damage levels induced from the mainshocks regardless of the retrofit scenarios.

• 항공우주시스템공학회지
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• 제10권2호
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• pp.27-33
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• 2016

For the continued airworthiness of aviation products, aviation authority requires that every manufacturer should provide ICA(Instruction of Continued Airworthiness) to their users, and the users should follow it by themselves or using another approved maintenance agent. To reduce the cost and improve performance quality of maintenance activities, lots of users tries to outsource this job. To perform maintenance or repair of other owned air products, an air carrier and aviation maintenance companies should obtain AMO(approval of maintenance organization). It means AMO is a postulation to enter MRO(Maintenance Repair and Overhaul) market. For that, this paper discusses the comparison of requirements and procedures of AMO system between Korea and US to help understand the AMO system, and then, tries to point out what improvement should be made to Korean AMO system to be more effective, efficient and safe.

• 대한안전경영과학회지
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• 제16권1호
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• pp.139-146
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• 2014

As Crosby notes, the most companies spend 15 to 20% of their sales dollars on quality costs. Generally the most effective way to manage quality costs is to avoid having defects in the first place. In this paper we have studied about the repair(service) problem of domestic gas boiler within warranty period. We develop a system, which man could find the cause of the problem at an early stage and could devise a countermove to the problem under supposing that the service(repair) rate follows exponential distribution and the product is manufactured lot-for-lot continually. Using the developed early sensing system. it is expected to improve the reliability of the product, to save expenses of company and to improve customer's satisfaction. And the system will be expended to incorporate information technology, which can detect the repair rate automatically.

• 한국국방경영분석학회지
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• 제18권2호
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• pp.114-125
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• 1992

A policy of periodic replacement with minimal repair at failure is considered for a complex system. Under such a policy the system is replaced at periodic times. iT(i=1,2, $\ldots$), while minimal repair is performed at any intervening system failures. The cost of the j-th minimal repair to the component which fails at age t is g(C(t). $c_j$ (t)), where C(t) is the age-dependent random part, $c_j$(t) is the deterministic part which depends on the age and the number of the minimal repair to the component, and g is a positive nondecreasing continuous function. The cost of replacement is expensive when the number of failures occurring in (0. T) is greater than a threshold level. The problem of determining the optimal replacement period, $T^{\ast}$, which minimizes the total expected cost per unit time over an infinite time horizon is considered. Various special cases are considered.

• 한국시뮬레이션학회논문지
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• 제20권3호
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• pp.119-127
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• 2011

전면정비란 일정기간동안 사용한 장비(기계, 설비 등)를 부품 단위로 분해하여 부품별로 수리를 한 후 재조립하는 과정을 의미다. 전면정비는 주로 항공기, 선박, 철도차량, 무기체계, 중장비 등과 같이 수명이 길고 고가인 장비를 운영하는 과정에서 발생한다. 이러한 정비 사업에서는 리드타임(Lead Time)을 단축시키는 것이 중요하며, 납기에 맞추어 정비를 완료할 수 있도록 생산시스템을 설계하는 것이 주요 관심사이다. 본 논문에서는 전면정비를 하는 정비 공장을 대상으로 3D시뮬레이션 도구인 $QUEST^{TM}$를 이용하여 시뮬레이션을 수행한 사례를 소개한다. 먼저 전면정비 공장의 공정특성과 시뮬레이션 모델 구축시 고려해야 하는 사항들을 중점적으로 설명하였다. 그리고 흐름생산방식과 셀생산방식 등 두 가지 해체작업 방식을 포함한 다양한 시뮬레이션 시나리오에 대해 시뮬레이션 실험을 통한 분석결과를 제시하였다.

• Computers and Concrete
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• 제32권3호
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• pp.287-302
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• 2023

Corrosion of reinforcing bars in reinforced concrete structures due to chloride attack in environments containing chloride ions is one of the most important factors in the destruction of concrete structures. According to the abundant reports that the corrosion rate around the repair area has increased due to the macro-cell current known as the incipient anode, it is necessary to understand the effective parameters. The main objective of this paper is to investigate the effect of the kinetic parameters of corrosion including the cathodic Tafel slope, exchange current density, and equilibrium potential in repair materials on the total corrosion rate and maximum corrosion rate in the patch repair system. With the numerical simulation of the patch repair system and concerning the effect of parameters such as electromotive force (substrate concrete activity level), length of repair area, and resistivity of substrate and repair concrete, and with constant other parameters, the sensitivity of the macro-cell current caused by changes in the kinetic parameters of corrosion of the repairing materials has been investigated. The results show that the maximum effect on the macro-cell current values occurred with the change of cathodic Tafel slope, and the effect change of exchange current density and the equilibrium potential is almost the same. In the low repair extant and low resistivity of the repairing materials, with the increase in the electromotive force (degree of substrate concrete activity) of the patch repair system, the sensitivity of the total corrosion current reduces with the reduction in the cathode Tafel slope. The overall corrosion current will be very sensitive to changes in the kinetic parameters of corrosion. The change in the cathodic Tafel slope from 0.16 to 0.12 V/dec and in 300 mV the electromotive force will translate into an increase of 200% of the total corrosion current. While the percentage of this change in currency density and equilibrium potential is 53 and 43 percent, respectively. Moreover, by increasing the electro-motive force, the sensitivity of the total corrosion current decreases or becomes constant. The maximum corrosion does not change significantly based on the modification of the corrosion kinetic parameters and the modification will not affect the maximum corrosion in the repair system. Given that the macro-cell current in addition to the repair geometry is influenced by the sections of reactions of cathodic, anodic, and ohmic drop in repair and base concrete materials, in different parameters depending on the dominance of each section, the sensitivity of the total current and maximum corrosion in each scenario will be different.

• 대한산업공학회지
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• 제33권3호
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• pp.364-372
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• 2007

The cost modeling of the LCD manufacturing system with the repair and the rework process is hard to achieve because of it's complex manufacturing process. The technical cost modeling divides each process separately and hierarchically, so it is very useful to calculate the total manufacturing cost of the complex manufacturing system. We applied the method to the complex LCD manufacturing system to obtain more accurate cost model. Yields are the most important control parameters in manufacturing. In this paper, we propose a yield based cost model for the LCD manufacturing system and reveal the relationship between manufacturing yield and cost. Through the model, we can estimate the manufacturing cost on the basis of yields that are control indicators of manufacturing. Some simulations are performed to observe the effects of the yield to the cost, and the results are coincide with the real situation. With the proposed model, we expect to develop some optimization problems for enlarging productivity in the LCD industry.

• Corrosion Science and Technology
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• 제7권1호
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• pp.6-12
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• 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.

• 제어로봇시스템학회논문지
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• 제14권5호
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• pp.432-437
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• 2008

This paper proposes a defect cell extraction algorithm for TFT-LCD auto-repair system. Auto defect search algorithm and automatic defect cell extraction method are very important for TFT-LCD auto repair system. In the previous literature[1], we proposed an automatic visual inspection algorithm of TFT-LCD. Based on the inspected information(defect size and defect axis, if defect exists) by the automatic search algorithm, defect cells should be extracted from the input image for the auto repair system. For automatic extraction of defect cells, we used a novel block matching algorithm and a simple filtering process in order to find a given reference point in the LCD cell. The proposed defect cell extraction algorithm can be used in all kinds of TFT-LCD devices by changing a stored template which includes a given reference point. Various experimental results show the effectiveness of the proposed method.

• International Journal of Reliability and Applications
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• 제11권2호
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• pp.107-122
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• 2010

This paper deals with the reliability analysis of a complex system, which consists of two subsystems A and B connected in series. Subsystem A has only one unit and B has two units $B_1$ and $B_2$. Marked process has been applied to model the complex system. Present reliability model incorporated two repairmen: supervisor and novice to repair the failed units. Supervisor is always there and the novice remains in vacation and is called for repair as per demand. The repair rates for supervisor and novice follow general and exponential distributions respectively and the failure time for both the subsystems follows exponential distribution. The model is analyzed under "Head of line repair discipline". By employing supplementary variable technique, Laplace transformation and Gumbel-Hougaard family of copula various transition state probabilities, reliability, availability and cost analysis have been obtained along with the steady state behaviour of the system. At the end some special cases of the system have been taken.