• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.9
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• pp.1169-1174
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• 2013

Most products are indeed governed by multiple failure modes. However, there are few cases in which reliability analysis applies to only one failure mode at a time. Furthermore, reliability data do not include information about failure modes, or the reliability analysis is performed using a representative failure mode. The Weibull shape parameter for failure modes is more important than one for products in the reliability qualification test. This paper presents reliability analysis methods for a mechanical component with multiple failure modes. These methods include the competing failure modes (CFM) method and the mixed Weibull method. Pneumatic cylinder test data with three failure modes are presented to estimate the shape parameter for each separate failure mode. In addition, reliability measures (B10 life, characteristic life) of the pneumatic cylinder considering three failure modes were compared with those assuming a single failure mode.

• Nuclear Engineering and Technology
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• v.42 no.6
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• pp.680-689
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• 2010

The crack-tip stress fields and fracture mechanics assessment parameters for a surface crack, such as the elastic stress intensity factor or the elastic-plastic J-integral, can be affected significantly by the adjacent cracks. Such a crack interaction effect due to multiple cracks can alter the fracture mechanics assessment parameters significantly. There are many factors to be considered, for instance the relative distance between adjacent cracks, the crack shape, and the loading condition, to quantify the crack interaction effect on the fracture mechanics assessment parameters. Thus, the current assessment codes on crack interaction effects (crack combination rules), including ASME Sec. XI, BS7910, British Energy R6 and API 579-1/ASME FFS-1, provide different rules for combining multiple surface cracks into a single surface crack. The present paper investigates crack interaction effects by evaluating the elastic stress intensity factor and the elastic-plastic J-integral of adjacent in-plane surface cracks in a plate through detailed 3-dimensional elastic and elastic-plastic finite element analyses. The effects on the fracture mechanics assessment parameters of the geometric parameters, the relative distance between two cracks, and the crack shape are investigated systematically. As for the loading condition, an axial tension is considered. Based on the finite element results, the acceptability of the crack combination rules provided in the existing guidance was investigated, and the relevant recommendations on a crack interaction for in-plane surface cracks are discussed. The present results can be used to develop more concrete guidance on crack interaction effects for crack shape characterization to evaluate the integrity of defective components.

• Journal of the Korean Society for Library and Information Science
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• v.45 no.2
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• pp.119-143
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• 2011

This study identifies the characteristics of recent citation-based indicators for assessing a single paper in the context of their co-relationships. Five predefined indicators were examined with three variants of h-index which are convened in this study; the formers are PageRank, SCEAS Rank, CCI, f-value, and single paper h-index and the latters are $h_S$-index, h1-index, and $h_S$1-index. The correlation analysis and cluster analysis were performed to group the indicators by common characteristics, after which the indicators were calculated with the dataset from KSCI DB. The results show statistical evidence that distinguishes h-index type indicators from others. The characteristics of the indicators were verified with citation frequency factors using correlation analysis. Finally, the implications for applications and further studies are discussed.

• Applied Chemistry for Engineering
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• v.16 no.5
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• pp.620-627
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• 2005

In this study, life cycle assessment (LCA) on one of corrugated cardboard box as functional unit was carried out. System boundary of this study divided according to raw material acquisition, corrugated cardboard manufacture and corrugated cardboard box manufacture stage. And environmental impacts are evaluated on each stage and sub-process. The impact categories are classified into eight categories of abiotic resource depletion, global warming stratospheric ozone depletion, photochemical oxidant creation, air acidification, eutrophication, ecotoxicity and human toxicity. From the results, it is found that environment impacts at raw material acquisition stage is the highest as about 92% of whole stage due to liner board manufacture stage. The highest environmental impacts at sub-process of corrugated cardboard and box manufacture stage is a single facer and D/W backer process that included as main process in corrugated cardboard manufacture, and is caused by used energies like electricity, B-C oil, and etc. And then diagnosis for clean production process system of package is carried out. Through diagnosis, on loss rate is reduced and inner pressure intensity of box is improved. After improvement, environmental impact was decreased about 3.8% compared with before improvement.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.7
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• pp.169-177
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• 2015

This paper described a fuzzy comprehensive evaluation method and implemented assessment system for multi-layer decision making. The proposed method is a assessment before bidding through the key questions using fuzzy comprehensive evaluation method and the entropy weights. The key questions are given by the wider investigation of major sports event organizers. The paper carried out evaluation of single factor and fuzzy comprehensive evaluation from low layer to high layer step by step. In order to verify the effectiveness of proposed method, we built the sports event management service platform (SEMSP) for assessment of applicant city. This method represents a unified one of the quantitative results and the qualitative results based on the judgment of experts.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1B
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• pp.8-14
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• 2000

This paper analyzes and accesses the gain of optically pumped surface-normal MQW optical amplifiers. The proposed amplifiers have the advantage of polarization independence, high coupling efficiency to and from optical fibers, and flexibility of operating wavelength. We analyzed the gain characteristics of 100 - 200-period MQWs and verified the dependence of a strained lattice and selective doping. Theoretical analysis of such MQWs showsa single-pass gain of 3 dB with broad operation bandwidth. A single-pass gain of 2.6 dB is obtained experimentally in an InGaAs/InGaAlAs MQW amplifier, which is compared with calculations. The use of Fabry-Perot interferometer (FPI) structure in an optical amplifier is a useful way to increase the gain, but causes a problem of narrow operation bandwidth when the single-pass gain is low. Therefore, a single-pass gain above 2to 3 dB is a prerequisite to achieve both a high gain and moderate operation bandwidth in FPI-structured opticalamplifiers. We have designed an FPI-structured surface-normal optical amplifier both with a high gain of broad operation bandwidth of 4.6mm, when a single-pass gain is 3 dB.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3D
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• pp.461-467
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• 2006

To detect individual vehicular speed, double loop detection technique has been widely used. This paper investigates four methodologies to measure individual speed using only a single loop sensor in a traveling lane. Two methods developed earlier include estimating the speed by means of (Case 1) the slop of inductance wave form generated by the sensor and (Case 2) the average vehicle lengths. Two other methods are newly developed through this study, which are estimations by measuring (Case 3) the mean of wheelbases using the sensor installed traversal to the traveling lane and (Case 4) the mean of wheel tracks by the sensor installed diagonally to the traveling lane. These four methodologies were field-tested and their accuracy of speed output was compared statistically. This study used Equality Coefficient and Mean Absolute Percentage Error for the assessment. It was found that the method (Case 1) was best accurate, followed by method (Case 4), (Case 2), and (Case 3).

• ETRI Journal
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• v.31 no.5
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• pp.489-499
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• 2009

This paper focuses on assessment and design of transmission systems for distribution of digital signals over standard Category-7A copper cables at speeds beyond 10 Gbps. The main contribution of this paper is on the technical feasibility and system design for data rates of 40 Gbps and 100 Gbps over copper. Based on capacity analysis and rate optimization algorithms, system parameters are obtained and the design implementation trade-offs are discussed. Our simulation results confirm that with the aid of a decision-feedback equalizer and powerful coding techniques, namely, TCM or LDPC code, 40 Gbps transmission is feasible over 50 m of CAT-7A copper cable. These results also indicate that 100 Gbps transmission can be achieved over 15 m cables.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.3
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• pp.46-55
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• 2001

Following the previous paper on development of the spatial location-allocation model of center villages (SLAMCV), this paper, the 2nd stage of the this study, aims to check up its applicability for several planning scenarios by the case study. Among 72 natural villages of Ucheon-myeon, Gangwon-do, Korea the highest single center was simulated as Uhang village and the higher double centers as Uhang and Jeonggeum villages, which coincided exactly with the existing centers. The SLAMCV was well operated for three planning scenarios such as selection of the 3rd center village and its hinter villages for Ucheon-myeon, Gargwon-do, Korea by dividing three living spheres, impact assessment evaluation of road improvement projects on the spatial accessibility, and analysis of centerality changes of settlement units by new road construction.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.spc
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• pp.75-87
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• 2020

The Korea Atomic Energy Research Institute (KAERI) has developed geological repository systems for the disposal of high-level wastes and spent nuclear fuels (SNFs) in South Korea. The purpose of the most recently developed system, the improved KAERI Reference Disposal System Plus (KRS⁺), is to dispose of all SNFs in Korea with improved disposal area efficiency. In this paper, a system-level safety assessment model for the KRS⁺ is presented with long-term assessment results. A system-level model is used to evaluate the overall performance of the disposal system rather than simulating a single component. Because a repository site in Korea has yet to be selected, a conceptual model is used to describe the proposed disposal system. Some uncertain parameters are incorporated into the model for the future site selection process. These parameters include options for a fractured pathway in a geosphere, parameters for radionuclide migration, and repository design dimensions. Two types of SNF, PULS7 from a pressurized water reactor and Canada Deuterium Uranium from a heavy water reactor, were selected as a reference inventory considering the future cumulative stock of SNFs in Korea. The highest peak radiological dose to a representative public was estimated to be 8.19×10^-4 mSv·yr^-1, primarily from ¹²⁹I. The proposed KRS⁺ design is expected to have a high safety margin that is on the order of two times lower than the dose limit criterion of 0.1 mSv·yr^-1.