• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.4
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• pp.306-313
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• 2011

The damage tolerance analysis is required to guarantee the structural safety and the reliability for aircraft components. The damage tolerance method, which evaluate the life considering the initial crack, considers a fatigue design model of the aircraft main structure. The fatigue crack growth life should be calculated in damage tolerance analysis and the inspection time to define the replacement cycle. In this paper, the damage tolerance analysis is performed for a turbine wheel which has complex geometry. The equation of the stress intensity factor for complex geometry is hard to know, so that they are usually processed by finite element analysis which takes long time. To solve this problem, the stress intensity factors at specified crack are obtained by the FEA and the crack growth life is evaluated using the surrogate model which is generated by the regression analysis of the FEA data. From the results, the efficiency of the crack growth life calculation and the damage tolerance analysis could be increased by taking the surrogate model.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.10
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• pp.435-442
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• 2006

One of the most important topics about the safety of electrical and electronic system is the reliability of the wiring system. The Time-Frequency Domain Reflectometry(TFDR) is a state-of-the-art system for detecting and estimating of the fault on a wiring. In this paper, We've considered the load resistance measurement on a coaxial cable using TFDR in a way of expanded application. The TFDR system was built using commercial Pci extensions for Instrumentation(PXI) and LabVIEW. The proposed real time TFDR system consisted of the reference signal design, signal generation, signal acquisition, algorithm execution and results display part. To implement real time system, all of the parts were programmed by the LabVIEW which is one of the graphical programming languages. Using the application software implemented by the LabVIEW, we were able to design a proper reference signal which is suitable for target cable and control not only the arbitrary waveform generator in the signal generation part but alto the digital storage oscilloscope in the signal acquisition part. By using the TFDR real time system with the terminal resistor on the target cable, we carried out load impedance measurement experiments. The experimental results showed that the proposed system are able not only to detect the location of impedance discontinuity on the cable but also to estimate the load resistance with high accuracy.

• Fire Science and Engineering
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• v.23 no.5
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• pp.125-132
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• 2009

In this study we could contribute to the development of a precise checking tool with which the reliability of the automatic fire detection systems was enhanced and the safety of the people was ensured. In the same way as the domestic technical standard, the portable smoke sensitivity tester, which was developed in this work, could be used to check the capability of the smoke detectors installed in the field. Its heater inside was warmed up to $400^{\circ}C$ in 40 seconds and the paper as a smoke source was burned to produce smoke for the test. With the Photoelectric smoke detector it was possible to measure and control the smoke concentration in a range from 0%/m to 25%/m. With the adjustment of rpm of the fan, it was possible to keep a constant wind velocity in a range from 20cm/sec to 40cm/sec.

• Fire Science and Engineering
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• v.34 no.4
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• pp.36-44
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• 2020

It is necessary to predict the activation time of fire detectors accurately to improve the reliability for evaluating the required safe egress time (RSET) in performance-based fire safety design. In this study, problems of the plunge test, which is widely applied in assessing fire detectors, were examined through experiments and numerical simulations. In addition, a new shield-cup test method was proposed to address these problems. A fire detector evaluator (FDE) developed in a previous study was applied to ensure measurement accuracy and reproducibility. During the plunge tests, a significant measurement error was observed in the activation time of the smoke detector because of the rapid flow change when the detector was input. However, during the shield-cup tests, slight changes occurred in the flow inside the FDE when the detector as exposed to smoke. In conclusion, the proposed shield-cup test method is expected to be useful for evaluating the response characteristics of fire detectors more accurately in simulated fire environments.

• Journal of the Korean GEO-environmental Society
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• v.13 no.4
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• pp.93-104
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• 2012

Efforts to understand and develop reasonable analysis methods for the uncertainty of ground have been made since the 20th century, and the concept of safety factor has been used. However, this concept has limitation in measuring the relative reliability of ground structures because the representative values of the actually used factors have uncertainty. Nevertheless, there is no method to completely remove uncertainty. In most cases, the ground investigation results in Korea are not enough for applying such statistical methods. Furthermore, performing a design without accurate investigation of consolidation state even though consolidation characteristics such as settlement and consolidation velocity vary greatly by the consolidation history can lead to many problems. Therefore, in this paper, as part of the effort to reduce the uncertainty of design around over consolidation ratio among the consolidation factors, the consolidation state was assessed on the basis of the results of high-quality laboratory tests that were performed in Gwangyang and Busan in the southern coast of Korea. Furthermore, consolidation characteristics such as over consolidation ratio by depth were proposed for different regions through statistical processes such as the test of normality and the removal of abnormal values to reduce the uncertainty of design parameters.

• Journal of Energy Engineering
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• v.23 no.2
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• pp.183-190
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• 2014

A Commercial Grade Item Dedication(CGID) for Korean operating nuclear power plants has been implemented since 2012. The CGID implementation and strategies for Korea are established as follows: CGID policy establishment, R&D of a specific methodologies of CGID, enrollment of third party organizations for CGID work, CGID program establishment for enrolled suppliers, establishment of training courses for certification, and CGID process development for quality class Q and A. Consequently, it is expected that these activities are enable to enhance the reliability and the safety of components and/or parts in nuclear power plants.

• Journal of Korean Society of Steel Construction
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• v.10 no.1 s.34
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• pp.37-45
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• 1998

The relational database system on fatigue strength was constructed, and the properties of fatigue life distribution were examined to analyze reliability and safety of metallic materials. Data manipulations were efficiently performed in relational fatigue strength database system using dependency diagram. Regardless of the distribution of fatigue strength, the proposed method, the Robust method and the complementary error function method using probability distribution, successfully estimated parameters of the 3-parameter Weibull distribution. The proposed criterion for estimating non-failure probability showed good results regardless of censoring time. The fatigue life distribution function described as a function of parameters of the Weibull distribution and applied stress ratio produced P-S-N characteristics reasonably.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.3
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• pp.535-541
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• 2009

In this paper, we present the improvement on the performance of driving part for single-phase MJ81 switch point machine which has been developed for localization. The single-phase motor's specification and reliability for speed and safety improvement of conventional line was investigated in "Development project for Speed-up on Conventional Line" We systemized the test procedure fur single-phase motor by investigating the feasibility for localization and the specification of function and performance. Also, we developed appropriate technology and proved the durability of the single-phase driving motor by executing synthesis test over 200,000 times.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.663-668
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• 2016

Increasing fuel economy and reducing air pollution have been unavoidable issues in the development of new cars, and one of the important methods is decreasing vehicle weight. Weight can be reduced by using lightweight materials such as aluminum alloy. Dynamic stiffness analysis was performed and compared for different materials for the knuckle for a car. The dynamic stiffness of 6061 aluminum alloy was about 30% higher than that of FCD600 cast iron. Usually, materials that have high dynamic stiffness show excellent vibration resistance because the dynamic stiffness can affect the vibration characteristics. In order to design a lighter and more reliable chassis component using 6061 aluminum alloy (AA6061-T6), a new knuckle shape is suggested by adding section ribs to an existing knuckle model. The effect of each design change on the reliability and component weight was investigated using computer aided engineering (CAE).

• Journal of the Korea Convergence Society
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• v.9 no.11
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• pp.45-51
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• 2018

Autonomous ship has been sportlighted as a core technology for the maritime industry in Industry 4.0 era. Autonomous ship is expeected to improve the safety, reliability, efficiency and environment significantly. For the realization of the autonomous ship, the remote control of the ship is one of the core functionality in addition to the autonomous ship control functionality in a ship. In this paper, we address a autonomous ship control system based on remote control. This paper proposes a remote control autonomous system and standardized ship-to-shore remote control protocol with for open platform. Finally, we implemented the system and tested with a real experiments with the test ship in order to demonstrate the feasibility of the proposed remote control autonomous system.