• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.93-101
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• 2022

RC Slab bridges in Korea account for more than 70% of the total bridges for more than 20 years of service. As the number of aging structures increases, the importance of safety diagnosis and maintenance of structures increases. For highway bridges, cracks are a main cause of deck deterioration, which is very closely related to the decrease in bridge durability and service life. In addition, the damage rate of expansion joints and bearings accounts for approximately 73% higher than that of major members. Therefore, this study defined damage scenarios combined with devices damages and deck deterioration. The stress distribution and maximum stress on the deck were then evaluated using design vehicle load and daily temperature gradient for single and combined damage scenarios. Furthermore, this study performed damage-spread analysis and predicted condition ratings according to a deck deterioration model generated from the inspection and diagnosis history data of cracks. The heterogeneous damages combined with the member damages of expansion joints and bearings increased the rate of crack area and damage spread, which accelerated the time to reach the condition rating of C. Therefore, damage to bridge members requires proper and prompt repair and replacement, and otherwise it can cause the damage to bridge deck and the spread of the damage.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.963-968
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• 2003

The continuous process systems usually consists of various components: driven rollers. idle rolls, load-cell and so on. Even a simple fault in a single component in the line may cause a catastrophic damage on the final products. Therefore it is absolutely necessary to diagnosis the components of the continuous systems. In this paper, an adaptive eccentricity compensation method is presented. And a new diagnosis method for transverse roll shape defects on rolling process is developed. The new method was induced from analyzing the rolling mechanism by using rolling force model, tension model, Hitchcock's equation, and measured delivery thickness of materials etc. Computer simulation results also show that the proposed diagnosis methods is very effective in the diagnosis of 3-D roll shape

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.131-131
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• 2000

In this paper, a design method of a fault diagnosis filter for a system with multiplicative faults which cause to change its parameters is developed. Linear time-invariant systems are dealt with in discrete-time domain. The residual which is sensitive to a damage of control surface of an aircraft by parity space approach is defined. Next, the fault is isolated by a new decision logic. Control reconfiguration is achieved by the result of fault diagnosis. Finally, the feasibility of the method is illustrated with a simulation study of a fault diagnosis system for a damaged control surface of an aircraft.

• Structural Engineering and Mechanics
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• v.70 no.6
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• pp.649-659
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• 2019

Vibration-based structural damage detection through optimization algorithms and minimization of objective function has recently become an interesting research topic. Application of various objective functions as well as optimization algorithms may affect damage diagnosis quality. This paper proposes a new damage identification method using Moth-Flame Optimization (MFO). MFO is a nature-inspired algorithm based on moth's ability to navigate in dark. Objective function consists of a term with modal assurance criterion flexibility and natural frequency. To show the performance of the said method, two numerical examples including truss and shear frame have been studied. Furthermore, Los Alamos National Laboratory test structure was used for validation purposes. Finite element model for both experimental and numerical examples was created by MATLAB software to extract modal properties of the structure. Mode shapes and natural frequencies were contaminated with noise in above mentioned numerical examples. In the meantime, one of the classical optimization algorithms called particle swarm optimization was compared with MFO. In short, results obtained from numerical and experimental examples showed that the presented method is efficient in damage identification.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.1
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• pp.78-83
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• 2005

Currently in Japan, the use of the small wind turbine is an upward trend. There are already many well established small wind turbine generators in use and their various failures have been reported. The most commonly sighted failure is blade damage. Thus the research purpose was set to develop a simple failure diagnostic system, where an Acoustic Emission (AE) signal was produced from the failure part of a blade which was measured by AE sensor. The failure diagnostic technique was thoroughly examined. Concurrently, the damage part of the blade was imitated, the AE signal was measured, and a FFT(Fast Fourier Transform) analysis was carried out, and was compared with the output characteristic. When one sheet of a blade was damaged 40mm or more, the level was computed at which failure could be diagnosed.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.198-201
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• 2003

The R.C Building will be superannuated as time passes. This program is generated by propagation of cracks. In order to manage such cracks, time and efforts, expense, etc. are required. In this study, glass sensors were embedding in a model beam and column and leakage of fluorescence and adhesive material was investigated. Further, currents in glass pipe were observed to find the leakage of liquid in glass pipes. Progressive cracks generated by cause the fracture of glass pipes. Therefore, the liquid become to flow and electric current stops, and the cracked part of the member can be found easily. Moreover, the adhesive delays progressive cracking system that responds in air, and the life of a structure can be made to extend. The purpose of this research is to develop of low price sensors that can perform of self-diagnosis in addition to ability of concrete repair concrete to damage.

• Journal of the Korean Society of Safety
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• v.32 no.4
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• pp.122-128
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• 2017

Recently, accidents such as human accidents are increasing rapidly due to natural disasters and changes in social conditions due to abnormal weather. As a result, damage has been causing massive damage unlike the past. In the case of small and medium enterprises excluding financial institutions and big company, there is no system for prevention and restoration for stable operation from various risks such as human and natural disasters. As the current disaster continues, public and private companies have raised the need for BCM, and with the introduction of the ISO22301 certification system, the company has been establishing and operating Enterprise Disaster Management Standards in the Ministry of Public Safety and Security since 2007. However, in most SMEs, it is hard to bear the input of internal labor and investment cost, and there is a lack of personnel with expertise to conduct BCM diagnosis. Therefore, in this paper, we will study the diagnosis level of enterprise continuity plan which is commonly used in Korea and abroad. Based on this, we will study the BCM system diagnosis method which can be applied to small and medium enterprises in Korea efficiently.

• Smart Structures and Systems
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• v.19 no.2
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• pp.195-202
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• 2017

The aim of this paper is to develop a novel method to determine the severity of a damage in a thin plate. This paper presents a novel fault detection and diagnosis approach employing a new electromagnetic acoustic transducer, called EMAT, together with a complex signal processing method. The method consists in the recognition of a fault that exists within the structure, the fault location, i.e. the identification of the geometric position of damage, and the determining the significance of the damage, which indicates the importance or severity of the defect. The main scientific novelties presented in this paper is: to develop of a new type of electromagnetic acoustic transducer; to incorporate wavelet transforms for signal representation enhancements; to investigate multi-parametric analysis for noise identification and defect classification; to study attenuation curves properties for defect localization improvement; flaw sizing and location algorithm development.

• 보존과학연구
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• s.29
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• pp.19-44
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• 2008

Sam-jon-bul or Three Buddha Image Carved on rock surface which is called Sam-jon-bul in Taean, state-designated national treasure No. 307, made in Baek-je Period, has two Buddha images and one Bodhisattva. The detached part of the Sam-jon-bul from wall rock has been attached through conservation treatment in 1995. Few study has been done on weathering condition of petrological point of view and damage while the surface of the Sam-jon-bul has been under serious weathering (relief) of loosing stone particles, and discoloration. In this study, it was made weathering damage maps, which show physical property of the material and state of damage of Sam-jon-bul, in order to dialogize how far the weathering has been done. It has been considered continuing on-site monitoring as necessity when Sam-jon-bul was covered with dew, which may have been caused by change in weather in and out of the protect building. It is necessary to set up detailed conservation plan for it by doing regular diagnosis on the influence of the protect building and weathering of Sam-jon-bul.

• Journal of Yeungnam Medical Science
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• v.1 no.1
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• pp.13-23
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• 1984

Acute renal failure refers to a rapid reduction in renal function that usually occurs in an individual with no known previous renal disease. Development of a complication of acue renal failure in critically ill surgical patients is not unusual, and it causes high morbidity and mortality. Acute renal failure can be divided as Pre-renal (functional), Renal (organic), and Post-renal (obstructive) azotemia according to their etiologies. Early recognition and proper correction of pre-renal conditions are utter most important to prevent an organic damage of kidney. These measures include correction of dehydration, treatment of sepsis, and institution of shock therapy. Prolonged exposure to ischemia or nephrotoxin may lead a kidney to permanent parenchymal damage. A differential diagnosis between functional and organic acute renal failure may not be simple in many clinical settings. Renal functional parameters, such as $FENa^+$ or renal failure index, are may be of help in these situations for the differential diagnosis. Provocative test utilyzing mannitol, loop diuretics and renovascular dilators after restoration of renal circulation will give further benefits for diagnosis or for prevention of functional failure from leading to organic renal failure. Converting enzyme blocker, dopamine, calcium channel blocker, and propranolol are also reported to have some degree of renal protection from bioenergetic renal insults. Once diagnosis of acute tubular necrosis has been made, all measures should be utilized to maintain the patient until renal tubular regeneration occurs. Careful regulation of fluid, electrolyte, and acid-base balance is primary goal. Hyperkalemia over 6.5 mEq/l is a medical emergency and it should be corrected immediately. Various dosing schedules for medicines excreting through kidney have been suggested but none was proved safe and accurate. Therefore blood level of specific medicines better be checked before each dose, especially digoxin and Aminoglycosides. Indication for application of ultrafiltration hemofilter or dialysis may be made by individual base.