• 한국전산유체공학회:학술대회논문집
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• 2005.04a
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• pp.187-190
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• 2005

In this study, the reliablility based design optimization is peformed for an aircraft wing. The flexiblility of the wing was assumed by considering the interaction modeled by static aeroelasticity between aerodynamic forces and the structure. For a multidisciplinary design optimization the results of aerodynamic analysis and structural analysis were included in the optimization formulation. The First Order Reliability Method(FORM) was employed to consider the uncertainty of the designed points.

• Journal of the Korean Data and Information Science Society
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• v.6 no.1
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• pp.73-83
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• 1995

We construct the approximate bootstrap confidence intervals for reliability (R) when the distributions of strength and stress are both normal. Also we propose percentile, bias correct (BC), bias correct acceleration (BCa), and percentile-t intervals for R. We compare with the accuracy of the proposed bootstrap confidence intervals and classical confidence interval based on asymptotic normal distribution through Monte Carlo simulation. Results indicate that the confidence intervals by bootstrap method work better than classical confidence interval. In particular, confidence intervals by BC and BCa method work well for small sample and/or large value of true reliability.

• Journal of Welding and Joining
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• v.27 no.4
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• pp.54-59
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• 2009

In the process to manufacture for metallic structures, control of welding deformation is one of an important problems connected with reliability of the manufactured structures so that welding deformation should be measured and controlled with quickly and actively. Also, welding parameters which have as lot of effects on welding deformation such as arc voltage, welding current and welding speed can also be controlled. The objectives for this study were to develop a simple 2-D FEM to calculate not only the transient thermal histories but also the sizes of fusion and heat-affected zone (HAZ) in multi pass arc welds including the butt and fillet weld type with dissimilar thickness, and to concentrate on a developed model for the finding the parameters of Godak's moving heat source model based on a GA. The developed model includes a GA program using MATLB and GA toolbox, and a batch mode thermal model using ANSYS software. Not only the thermal model was verified by comparison with Goldak's work but also the developed model was validated with molten zone section experimental data.

• Journal of Korean Society for Quality Management
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• v.26 no.4
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• pp.265-276
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• 1998

A commercial nuclear power station contains at least two emergency diesel generators(EDG) to control the risk of severe core damage during station blackout accidnets. Therefore, thereliability of the EDG's to start and load-run on demand must be maintained at a sufficiently high level. Until now, a simple assessment of start and load-run success rates was used to calculate the EDG reliability. However, this method has been found to contain many defects. Recently, the work of Martz et al.(1996) proposed the use of the Bayes estimator to find EDG reliability. Shim(1996) proposed a confidence interval for the Bayes estimator, compare the above two methods. In this paper, we introduce the notion of "Composite Reliablility" to estimate the reliability of nuclear-power plant EDG, and using practical examples, illustrate which method is more a, pp.opriate in our situation.situation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.7
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• pp.628-639
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• 1991

A new efficient method for GaAs MESFET model parameter extraction is proposed, which is based on the bias dependance of each parameter characteristics derved from the analytic model. The requiremnts of the method are only small-signal S-parameter measurements under the three bias variations. Fixation of the linear model parameter values in the optimization process is made using the sensitivity information of the model parameter obtained by the weighted Broyden update method, it is to improve the uniqueness and reliablility of the solution. The validity of the extracted values of the FET model parameters is confirmed by comparing the simulation results with the experimental data.

• Proceedings of the Korea Concrete Institute Conference
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• 1990.10a
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• pp.41-44
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• 1990

There is the need to balance safety, economy and serviceability in all phases of society proboems. This is especially true in structural code formulation, where a framework is established by which practicing structural enginers can be assured of designing structures that reasonably meet the above three objectives. The existeing design codes, which are generally based on the structural theory and certain engineering experience, do not realistically consider the uncertainties of loads and resistances and the basic reliability concepts. The purpose of the present study is therefore to develop the realistic reliablility-based design criteria to secure adequate safety and reliability, and to derive the models for partial and combined resistance factor formats.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.832-837
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• 2001

In this paper, we analyzed the characteristic of the broken section for bolts fastening the generator casing, and according to the frequency analysis, we grasped the characteristic of the excited force, traced the path of the exciting source so that we examined a factor of transient vibration of the generator casing. Even if it appears transient vibration again, we applied spring washer and more tensile bolt to the casing to minimize the fracture. By solving troubles of the generator rotor, we reduced the vibration amplitude to the normal condition. So we obtain much more the reliablility of the generator.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.12
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• pp.69-76
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• 1998

This paper proposes a matrix which represents the confidence in the rotation components of the Iterative Closest Point (ICP) algorithm is image registratiion, The reliability of the ICP algorithm depends on the shape of the object. For example, an object with more complex features shows higher reliablility than the one with rotation symmetry such as a cylinder. We show that the reliablity of the ICP algorithm can be estimated when the input range data has additive noise. Finally, we demonstrate that the proposed reliability formula is in good agreement with the computer simulation.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.4
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• pp.103-116
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• 1994

The objective of this study was to determine the criteria for density and moisture content measurements made with a nuclear density meter on common materials in the construction field. The study also sought to test a full-type nuclear density meter in controlling the density of overlay layers( 2.5~5.0cm). In order to determine the accuracy and reliablility of nuclear guage measurements made on construction materials, laboratory and field tests were conducted. Wooden blocks( 65 x 45 ${\times}$ 50 cm) and a special steel compactor( 4.7kg) were constructed in order to carry out tests which were conducted on three different materials; coarse gramed soil, fine grained soil, and AC material. Throughout all laboratory and field tests, the nuclear density and moisture content were determined using Humboldt 5OOLP nuclear gauge. The tests on subgrade material entailed obtaining density measurements by means of both the sand replacement method and the nuclear density meter. The results of the sand replacement method were then compared to the readings recorded bu the meter. As in the subgrade material tests, density measurements made during AC pavement tests were also determined using the unclear meter in addition to a second means; through the core method. The meter readings and core densties were compared as was done in the tests on subgrade materials. The correlation between the results of the sand replacement test( also, the core method) and meter readings on subgrade material was then determined. Sirnilarly, the observed results were then analyzed through linear regression. The tests to determine thin-lift density by means of a full-type nuclear density meter also conducted on the overlay layers( about 4. 8cm thickness) above AC pavements at road construction sities in Korea.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.45-51
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• 2019

Modern file systems have journaling mechanism to maintain their stored state consistently even under unexpected system crashes or disasters. However, the journaling makes I/O throughput lower. This performance degradation comes from the ordering mechanism between the data buffer and metadata buffer and two-staged buffer writing. Especially, if the data buffer and metadata buffer are journalled at the same time, then it incurs significant performance degradation due to the two-staged writing. That shows the trade-off relation-ship between I/O performance and system reliability. In this paper, we propose RFJ: a reliable and fast jour-naling mechanism to deal with this trade-off relationship. We propose an ordering enforced writeback journaling mode and selective journaling mechanism. The Ordering enforced writeback journaling mode achieves low I/O latency and the selective journaling mechanism achieves high reliability. The experimental result shows that the performance of RFJ is almost 5x faster than the journal mode of Ext3 file system but it still supports the same reliability with the journal mode.