• Journal of Applied Reliability
• /
• v.12 no.3
• /
• pp.131-138
• /
• 2012

A design of reliability qualification test based on performance distribution is developed. In general, the performance of an item degrades as the time goes by and the failure of an item occurs when the performance degradation reaches the pre-determined critical level. This article considers the reliability qualification test based on a more tightened critical value at the earlier stage to reduce the evaluation testing time and cost. A numerical example is provided to illustrate how to use the developed reliability qualification test.

• Proceedings of the KIEE Conference
• /
• 2002.07c
• /
• pp.1727-1729
• /
• 2002

To cope with increasing of electric power demand in metropolitan areas, large capacity underground power cables are needed. Under such situations, our company has developed 345kV XLPE insulated cable and accessories. As the final step of development of the 345kV XLPE cable and accessories, the pre-qualification test was carried out on the test line composed of cables, pre-fabricated joints, EB-Gs and EB-As. This paper sums up the pre-qualification test conditions and the results.

• Journal of Applied Reliability
• /
• v.10 no.1
• /
• pp.1-9
• /
• 2010

In general, the performance of a component degrades as time goes by and failure of a component occurs when the performance degradation reaches a pre-specified level. It is difficult to obtain the failure time distribution data or the necessary number of failure data especially for the metal or machine part. Thus, a design of reliability qualification test based on performance distribution is more effective than failure time distribution. In this study, a performance-based reliability qualification test is developed and a numerical example is provided to illustrate the use of the developed reliability qualification test. This approach could be applied to many kinds of metal or machine part whose magnitude of strength could not be evaluated during at any random points but judgement can be made by only failure of the part. Besides, it is also possible that any parts which have a similar failure characteristics could be applicable to the developed reliability qualification test.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.5
• /
• pp.1062-1067
• /
• 2011

As the expension of metropolis and increasing of housing site, GIL(Gas Insulated Line) comes to the fore as an alternative to overhead transmission line avoided by local resident. The certification and experimental test for the GIL is now in progress in under ground test lab, Go-chang. For the test, we propose a method of PQ(pre-qualification) test which is essential for development and field application in this paper. The test following this method take about 200 days or 300 days under the circumstances.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2017.05a
• /
• pp.65-68
• /
• 2017

In this paper, a multipactor test for the space qualification model of the X-band dual-mode high-power channel filter for high-speed data transmission of geostationary satellite observation payloads was conducted and compared with the 8 dB margin required for design. It was confirmed that analytically required margins were met through testing and that satisfactory test results were obtained. The design and test of the multipactor are tested according to the ECSS standard. Based on this, it is suggested that if the margin of design is sufficiently secured, it can be used in the development of the filter for space qualification model without any test.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.23 no.1
• /
• pp.30-40
• /
• 2015

Recently, the need of RPA(Remotely Piloted Aircraft) pilots is increasing rapidly with many requirements in order to be a beginner RPA pilot, including basic flight training, instrument flight qualification training, and aircraft type switching training. When RPA pilot gets disqualified, there will be generated much waste of efforts and expenses of trainees those pilots who are disqualified. Therefore, the methodology of pre-verifying those pilots who are not proper as RPA pilots through various scientific methods will save time and expenses with pre-reducing the pilots who will get disqualified later on. The methodology of aptitude test of RPA pilots is laid out as a consideration of pre-study of RPA pilots work analysis, and select types of aptitude test. A suitability of aptitude test is verified. In order to diagnose the flight aptitude precisely, it requires to be developed. Flight aptitude test tools might be connected with training program which could foster piloting aptitude with pre-diagnosing RPA pilot trainee selecting process. For that reason, we made an experiment in order to verify credibility and suitability of these selected programs with developing RPA pilot aptitude test tools. And also, we analyzed relationships among characteristics, analysis of data, and variables to verify the efficiency of data from prior experiment. Through this thesis, we expect to raise efficiency of flight training by providing pre-flight aptitude test information of RPA pilots.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.11a
• /
• pp.19-20
• /
• 2023

The pre-qualification system related to floor impact noise is considered ineffective, and thus, the introduction of a post-verification system is being prepared. This is because the performance, which was notarized in the qualification test due to various reasons, was not uniformly confirmed on building construction fields. Industry practitioners perceive that this is due to the influence of factors such as the flatness, levelness and/or thickness of the floor. However, it is very difficult to confirm such facts in a short period of time on the fields, and since the practical application of technology to measure and evaluate quantitatively and the establishment of a system are insufficient, it cannot be said to be a problem that can be brought to the surface. In fact, even when considering the conventional measurement of the dynamic modulus of elasticity, measurements are performed under controlled variables, such as placing a 200mm×200mm buffer material on a flat test-floor. However, in the fields, it is common to lay down larger productions(for example, 900mm×600mm) on the bare floor where significant variables are not controlled, and to construct finishing layers corresponding to the pre-qualified floor system without separately confirming the realization of the dynamic modulus of elasticity in the field conditions. In this study, spatial information of the bare floor on the field was measured and evaluated through a laser scanner. Technical methods for assessing the smoothness, flatness, and thickness of construction surfaces were reviewed, providing key insights for grading the quality of construction based on these criteria. Through further detailed and thorough investigations, it is expected that results suitable for practical application and systematization will be derived.

• Corrosion Science and Technology
• /
• v.15 no.2
• /
• pp.84-91
• /
• 2016

The transport and deposition of corrosion products in pressurized water nuclear reactor (PWR) steam generators have led to corrosion (SCC, denting etc.) problems. Lancing, mechanical cleaning and chemical cleaning have been used to reduce these problems. The methods of lancing and mechanical cleaning have limitations in removing corrosion products due to the structure of steam generator tubes. But high temperature chemical cleaning (HTCC) with EDTA is the most effective method to remove corrosion products regardless of the structure. However, EDTA in chemical cleaning aqueous solution and chemical cleaning environments affects the integrity of materials used in steam generators. The nuclear power plants have to perform the pre-test (also called as qualification test (QT)) that confirms the effect on the integrity of materials after HTCC. This is one of the series studies that assess the effect, and this study determines the effects of 20 % EDTA aqueous solution on defective tubes in high temperature chemical cleaning environments. The depth and magnitude of defects in steam generator (SG) tubes were measured by eddy current test (ECT) signals. Surface analysis and magnitude of defects were performed by using SEM/EDS. Corrosion rate was assessed by weight loss of specimens. The ECT signals (potential and depth %) of defective tubes increased marginally. But the lengths of defects, oxides on the surface and weights of specimens did not change. The average corrosion rate of standard corrosion specimens was negligible. But the surfaces on specimens showed traces of etching. The depth of etching showed a range on the nanometer. After comprehensive evaluation of all the results, it is concluded that 20 % EDTA aqueous solution in high temperature chemical cleaning environments does not have a negative effect on defective tubes.

• Journal of Welding and Joining
• /
• v.31 no.6
• /
• pp.1-7
• /
• 2013

In nuclear power plants, lined carbon steel pipes or PCCPs (pre-stressed concrete cylinder pipes) have been widely used for sea water transport systems. However, de-bonding of linings and oxidation of PCCP could make problems in aged NPPs (nuclear power plants). Recently at several NPPs in the United States, the PCCPs or lined carbon steel pipes of the sea water or raw water system have been replaced with HDPE (high density polyethylene) pipes, which have outstanding resistance to oxidation and seismic loading. ASME B&PV Code committee developed Code Case N-755, which describes rules for the construction of buried Safety Class 3 polyethylene pressure piping systems. Although US NRC permitted HDPE materials for Class 3 buried piping, their permission was limited to only 10-year operation because of several concerns including the quality of fusion zone of HDPE. In this study, various requirements for fusion qualification test of HDPE and some regulatory issues raised during HDPE application review in foreign NPPs are introduced.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2006.04a
• /
• pp.181-185
• /
• 2006

Image co-registration is the process of overlaying two images of the same scene, one of which represents a reference image, while the other is geometrically transformed to the one. In order to improve efficiency and effectiveness of the co-registration approach, the author proposed a pre-qualified area matching algorithm which is composed of feature extraction with canny operator and area matching algorithm with cross correlation coefficient. For refining matching points, outlier detection using studentized residual was used and iteratively removes outliers at the level of three standard deviation. Throughout the pre-qualification and the refining processes, the computation time was significantly improved and the registration accuracy is enhanced. A prototype of the proposed algorithm was implemented and the performance test of 3 Landsat images of Korea showed: (1) average RMSE error of the approach was 0.436 Pixel (2) the average number of matching points was over 38,475 (3) the average processing time was 489 seconds per image with a regular workstation equipped with a 3 GHz Intel Pentium 4 CPU and 1 Gbytes Ram. The proposed approach achieved robustness, full automation, and time efficiency.