• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.675-678
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• 1999

Rebar corrosion in concrete containing both chloride ions and calcium nitrite inhibitors were investigated by the various electrochemical methods. Rebar corrosion was accelerated by applying the impressed current to the rebar in concrete. Effect of chloride content and inhibitors on rebar corrosion were evaluated. Accelerated corrosion technique is the method to measure the time to the initiation of cracks of reinforced concretes, by applying constant voltage between rebar and the stainless steel cathedes. The increase of concentration of chloride ions in concrete result in the increase in anodic currents and the reduction of time to crack. However addition of inhibitors did not improve corrosion resistance of rebar in concrete. Rebar corrosion in concrete with chloride ions and inhibitors was also analyzed by the immersed tests though the mesurement of corrosion potentials.

• Annals of Clinical Neurophysiology
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• v.1 no.1
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• pp.70-75
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• 1999

Trancranial Doppler(TCD) monitoring is a new application of ultrasonography which allows the nonivasive detection of blood flow velocity in the horizontal (M1) segment of the middle cerebral artery (MCA) and detects microembolic phenomena in the cerebral circulation. Recent studies emphasized the potential of using this technique in vascular surgery (carotid endarterectomy, cardiopulmonary bypass), interventional and intensive care setting. Although the disparity between CBF and blood flow velocity and number of microemboli could be used to prevent cerebral ischemic and embolism based on clinical studies. A reduction of more than 60% of MCA can reflex hemodynamic ischemic state and acoustic feedback of high intensity transient signals(HITS) from the TCD monitoring unit has a direct influence on surgical technique. TCD monitoring can immediately provide information about thromboembolism and hemodynamic changes, which may be a useful tool in the study and prevention of stroke.

• Health Policy and Management
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• v.13 no.3
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• pp.21-34
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• 2003

Patient revisit to used hospital is a key factor in determining a health care organization's competitive advantage and survival. This article examines the relationship between customer's satisfaction and his/her revisit associated with three different methods which are the Chi Square Automatic Interaction Detection(CHAID) for segmenting the outpatient group, logistic regression and neural networks for addressing the outpatient's revisit. The main findings indicate that the important factors on outpatient's revisit are physician's kindness, nurse's skill, overall level of satisfaction, hospital reputation, recommendation, level of diagnoses and outpatient's age. Among these ones, physician's kindness is the most important factor as guidelines for decision of their revisit. The decision maker of hospital should select the strategy containing the variable amount of the level of revisit and size of outpatient's group under the constraint on the hospital's time, budget and manpower given. Finally, this study shows that neural networks, as non-parametric technique, appear to more correctly predict revisit than does logistic regression as a parametric estimation technique.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.6
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• pp.686-695
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• 2012

This paper proposes a noncontact thermography technique for fatigue crack evaluation under a cyclic tensile loading. The proposed technique identifies and localizes an invisible fatigue crack without scanning, thus making it possible to instantaneously evaluate an incipient fatigue crack. Based on a thermoelastic theory, a new fatigue crack evaluation algorithm is proposed for the fatigue crack-tip localization. The performance of the proposed algorithm is experimentally validated. To achieve this, the cyclic tensile loading is applied to a dog-bone shape aluminum specimen using a universal testing machine, and the corresponding thermal responses induced by thermoelastic effects are captured by an infrared camera. The test results confirm that the fatigue crack is well identified and localized by comparing with its microscopic images.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.120-122
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• 2005

With the commercial availability of very high resolution satellite imagery, the concealment of national confidential targets such as military facilities became one of the most bothering task to the image distributors. This task has been carried out by handwork masking of the target objects. Therefore, the quality of the concealment was fully depends on the ability and skill of a worker. In this study, a spectral clustering based technique for the seamless concealment of confidential targets in high resolution imagery was developed. The applicability test shows that the proposed technique can be used as a practical procedure for those who need to hide some information in image before public distribution

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.4
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• pp.185-194
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• 2007

This paper presents a motor selection technique for a manipulator design that is used in a multipurpose dog-horse robot. Since the dynamics of a manipulator and its servo drives are closely related to each other, it requires a repetitive analysis to determine a suitable motor. In order to simplify this procedure, Straete et al. proposed a simple normalization method to separate the load dependent terms and the motor dependent terms. This technique is adopted in this paper for selecting a motor in designing a manipulator.

• Journal of Sensor Science and Technology
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• v.23 no.5
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• pp.299-304
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• 2014

Optimizing the performance of a composite sensor array is necessary when the number of sensors to choose from is large. In this paper, we present a chemical sensors array optimization method using Wilks Lamda algorithm applicable a device to detect low concentration of alcohol from driver's exhale breath for interlocking engine ignition preventing drink-driving. More than 20 chemical sensors fabricated different synthetic stuffs and heater temperatures by collaborators were nominated, 5 sensors were selected for optimal sensors array using the method, and alcohol samples were well discriminated from the interference gases inside the vehicle. It has been confirmed by Principal Component Analysis (PCA).

• Journal of Mechanical Science and Technology
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• v.18 no.6
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• pp.879-894
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• 2004

The image processing technique is simple and, in principle, can handle particles with various shapes since it is based on direct visualization. Moreover, a wide measurement area can be covered with appropriate optical arrangement. In the present paper, various techniques of image processing for sizing and counting particles are reviewed and recent developments are introduced. Two major subjects are discussed in detail: identification of particles (i.e., boundary detection and pattern recognition) and determination of in-focus criteria. Finally, an overall procedure for image processing of spray particles is suggested.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.11
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• pp.1530-1535
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• 2018

In this paper, A technique for detecting contact loss at the input power of a railway vehicle has been studied when the contact loss occurs in the feed system. The impedance of the actual railway line was applied to the modeling of the feed system, and modeling was performed based on the performance of the electric railway vehicle. The input voltage and current of the railway vehicle through modeling were analyzed by applying TEO and STFT signal processing technique.

• Structural Engineering and Mechanics
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• v.36 no.2
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• pp.129-147
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• 2010

This study deals with the viability of using a designed geometrical model consists of plane, polar coordinates (PC) and span length in the determination of bridges deformation. The data of a Tianjin Yonghe bridge located in the southern part of China as collected by RTK-DGPS technique and Accelerometer were used in the analysis. Kalman filter and fast Fourier transformation (FFT) analyses were used to determine the frequency. The results indicate that the designed plane and PC geometrical model are easy to calculate the long-time structural deformation monitoring. In addition, the observed frequency using GPS with the rate of 20 Hz doesn't give correction natural frequency of the observation structures.