• Journal of radiological science and technology
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• v.32 no.1
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• pp.17-24
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• 2009

Noise evaluation for an image has been performed by root mean square (RMS) granularity, autocorrelation function (ACF), and Wiener spectrum. RMS granularity stands for standard deviation of photon data and ACF is acquired by integration of 1 D function of distance variation. Fourier transform of ACF results in noise power spectrum which is called Wiener spectrum in image quality evaluation. Wiener spectrum represents noise itself. In addition, along with MTF, it is an important factor to produce detective quantum efficiency (DQE). The proposed evaluation method using Wiener spectrum is expected to contribute to educate the concept of Wiener spectrum in educational organizations, choose the appropriate imaging detectors for clinical applications, and maintain image quality in digital imaging systems.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1651-1664
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• 2013

Precise analysis on deterioration processes of road pavements is not so simple matter due to severe uncertainty originated from a lot of explanatory variables engaged in. For those reasons, most analytical models for pavement deterioration prediction have often preferred to probabilistic approaches than deterministic models. However, the general probabilistic approaches that treat overall characteristics of population or entire sample would not be suitable for providing detail or localized information on their changing process. Considering the aspects, this paper aimed to suggest a stochastic disaggregation method to analyze the localized deterioration speeds and its variances changed by time and condition states. In addition, life expectancies and their uncertainty were estimated by probabilistic algorithm using the disaggregated stochastic process. For an empirical study, pavement inspection data (crack) accumulated from 2003 to 2010 from Korean national highway network was applied. This study can contribute to securing reliability of life cycle cost analysis, which is one of the primary analyses in road asset management, with much advanced deterioration forecasting functions. In addition, it would be meaningful trials as fundamental research for preventive maintenance strategy that demands essential understanding on changing process of the deterioration speed of pavement.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.3
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• pp.251-259
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• 2004

The prediction accuracy of prestress plays an important role in the quality of maintenance and the decision on rehabilitation of infrastructure such as prestressed concrete bridges. In this paper, the Bayesian statistical method that uses in-situ measurement data for reducing the uncertainties or updating long-term prediction of prestress is presented. For Bayesian analysis, prior probability distribution is developed to represent the uncertainties of creep and shrinkage of concrete and likelihood function is derived and used with data acquired in site. Posterior probability distribution is then obtained by combining prior distribution and likelihood function. The numerical results of this study indicate that more accurate long-term prediction of prestress forces due to creep and shrink age is possible.

• Journal of the Korean Society for Railway
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• v.13 no.5
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• pp.500-503
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• 2010

Until now, the track circuit with railroad which is a part of an electrical circuit wad used only for the detection of the train location, but as train speed is up to be higher, in order to overcome the limits of ground signal system the railway signal system has changed from the ground signal system to a cab signal system. The power source of the track circuit has also changed from a direct current or a high voltage impulse to an alternating current with high frequency which is a part of the audio frequency. To improve the maintenanability and according to the environment condition, the railway roadbed is rapidly changed to the ferroconcrete roadbed. In case of a track circuit to use an alternating current with high frequency as power source at a ferroconcrete roadbed, the characteristic of the track circuit is brought on a change from a loss of the magnetic combination instead of a leakage current from electric insulation which was caused by the reinforcing iron pod with lattice shape for durability. This paper is shown the influence and the loss of the signal current at AF track circuit on a ferroconcrete in the simulation sheets and presented a proposal for the preventive method from reduction of signal current.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.623-628
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• 2007

Metro Subway System is widely known as the leader of public transportation in a metropolitan area. The signal interlocking is one of the most important organs that plays a major role in the system. By improving the quality of signal interlocking on of the traffic system and keeping its maintenance on a high level will not only repair the current state, but it will also let the PLC(Programmable Logic Controller). The Non-Vital relay of No. 3, 4 Line are the most one of the unstable system, device, which underwent a process of fine manufacture establishment and a close examination, obtained as a new device. Utilizing the equipment with cautious preservation on the system will enhance the current state of the signal device. Especially, the test for improvement and development based upon the technique that decreases the frequency of defect produced will further precipitate its efficiency. With authorization of imposing the newly made equipment will bring improvement to the signal technology and to the industry at largest extent.

• Journal of Internet of Things and Convergence
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• v.5 no.1
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• pp.29-34
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• 2019

A bag filter collector is a kind of air purifier that organizes several or dozens of filters to purify fine dust and release clean air into the atmosphere. If the bag filter length is less than 5m, the dust and fume attached to the bag filter could be effectively removed by passing the compressed air generated by the diaphragm valve through the venturi. Injectors that are more efficient and economical are urgently needed to achieve satisfactory results for long-bag exhaustion of more than 7 meters. In the case of existing domestic and foreign injectors, a number of blow tubes were dismantled during maintenance, and the injector and blow tube were combined to pose a number of problems, including inconvenience of work due to weight increase. In this study, injector flow for the development of the best use of interpretation of the coanda effect and the fourth round of industrial technology Intelligent automation of exhaustion, have been engineered energy than standard equipment. lowering costs and filter life to radically improve the commercial studies.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.567-570
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• 2006

Recently because of rising of international oil prices, plant industry market has been active and purchase orders of big project are tending upwards. For strengthening of overseas plant competitive power and successful project operating, it is essential the project management technology and method. but procurement management of plant industry has evaluated uncompetitive. In this study, we analyzed the process of procurement founded and main contents and information. we study flowing of procurement information. user and creation time though detailing procurement information, then, we suggest the Contents Classification System and Management Model of Procurement Information.

• Journal of KIISE:Software and Applications
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• v.31 no.10
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• pp.1286-1303
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• 2004

Component-based Development is gaining a wide acceptance as an economical software development paradigm to develop applications by utilizing reusable software components. Well-defined interface manages coupling and cohesion between components, minimizes the effect on the user in case of component evolvement, and enhances reusability, extendibility and maintainability. Therefore, study on systematic development process and design guidelines for component interface has been required since the component has been introduced. In this paper, we propose three types of interfaces based on software architecture layers and functionality types； Provided Interface which provides functionality of a component, Required Interface which specifies required functionality that is provided by other components, and Customize Interface which tailors the component to customer's requirement. In addition, we suggest design criteria for well-designed interface, and systematic process and instructions for designing interface. We firstly cluster operations extracted from use case model and class model to identify Provided interfaces, and design Customize interfaces based on artifacts for variability. We also specify Required interfaces by identifying dependency among interfaces. Proposed interface design method provides traceability, throughout the component interface design. And furthermore, proposed guidelines support practical design for high quality component based on a case study.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.6
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• pp.483-489
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• 2016

The typical methods used for inspecting ferromagnetic pipes include the ultrasonic testing (UT) contact method and the following non-contact methods: magnetic flux leakage (MFL), electromagnetic acoustic transducers (EMAT), and remote field eddy current testing (RFECT). Among these methods, the RFECT method has the advantage of being able to establish a system smaller than the diameter of a pipe. However, the method has several disadvantages as well, including different sensitivities and difficult-to-repair coil sensors which comprise its array system. Therefore, a giant magneto-resistance (GMR) sensor was applied to address these issues. The GMR sensor is small, easy to replace, and has uniform sensitivity. In this experiment, the GMR sensor was used to measure remote field and defect signal characteristics (in the axial and radial directions) in a ferromagnetic pipe. These characteristics were measured in an effort to investigate standard defects at changing depths within a pipe. The results show that the experiment successfully demonstrated the applicability of the GMR sensor to RFECT signal detection in ferromagnetic pipe.

• Journal of Korean Society of Transportation
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• v.31 no.2
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• pp.80-89
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• 2013

The purpose of this research is to optimize the line planning of the intercity passenger railway. In this study, the line planning problem has been formulated into a mixed integer programming by minimizing both user costs (passenger's total travel time) and operator costs (operation, maintenance and vehicle costs) with multiple train types. As a solution algorithm, the branch-and-bound method is used to solve this problem. The change of travel demand, train speed and the number of schedules have been tested through sensitivity analysis. The optimal stop-schedules and frequency as well as system split with respect to each train type have been found in the case study of Kyoung-bu railway line in Korea. The model and results of this research are useful to make a decision for railway operation strategy, to analyze the efficiency of new railway systems and to evaluate the social costs of users and operators.