• International Journal of Reliability and Applications
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• v.18 no.2
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• pp.45-63
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• 2017

In this paper, we have formulated optimum Accelerated Life Test (ALT) plan for a parallel system with two independent components using masked data with ramp-stress loading scheme and Type-I censoring. Consider a system of two independent and non-identical components connected in parallel. Such a system fails whenever all of its components has failed. The exact component that causes the system to fail is often unknown due to cost and time constraint. For each parallel system at test, we observe its system's failure time and a set of component that includes the component actually causing the system to fail. The stress-life relationship is modelled using inverse power law, and cumulative exposure model is assumed to model the effect of changing stress. The optimal plan consists in finding out the optimum stress rate using D-optimality criterion. The method developed has been explained using a numerical example and sensitivity analysis carried out.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.955-958
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• 2005

In this study, the wind load characteristics for a transmission tower is investigated considering the effect of the transmission lines through stochastic analysis. The assemblage of the transmission line and insulator are modeled as a double pendulum system connected to the SDOF model of the tower It is observed that the background component of the overturing moment induced by the wind response of the transmission line has considerable portion in the total overturning moment. Based on this result, a rotational viscoelastic damper (VED) is proposed for the mitigation of the transmission line reactions, which act as wind load transferred to the tower. To verify the effectiveness of the proposed strategy, time history analysis is conducted for different wind velocities and VED damping constants. From the analysis, the proposed VED is proved to be effective for mitigation of the background component rather than the resonance component of the transmission line reaction.

• Structural Engineering and Mechanics
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• v.54 no.2
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• pp.379-392
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• 2015

A number of acceleration-based damage detection methods have been developed but they have not been widely applied in engineering practices because the acceleration response is insensitive to minor damage of civil structures. In this article, a damage detection approach using the long-gauge strain sensing technology and the principle component analysis technology is proposed. The Long gauge FBG sensor has its special merit for damage detection by measuring the averaged strain over a long-gauge length, and it can be connected each other to make a distributed sensor network for monitoring the large-scale civil infrastructure. A new damage index is defined by performing the principle component analyses of the long-gauge strains measured from the intact and damaged structures respectively. Advantages of the long gauge sensing and the principle component analysis technologies guarantee the effectiveness for structural damage localization. Examples of a simple supported beam and a steel stringer bridge have been investigated to illustrate the successful applications of the proposed method for structural damage detection.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.6
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• pp.390-395
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• 2005

Sunspots are dark areas that grow and decay on the lowest level of the sun that is visible from the Earth. Shot-term predictions of solar activity are essential to help plan missions and to design satellites that will survive for their useful lifetimes. This paper presents a parallel-structure fuzzy system(PSFS) for prediction of sunspot number time series. The PSFS consists of a multiple number of component fuzzy systems connected in parallel. Each component fuzzy system in the PSFS predicts future data independently based on its past time series data with different embedding dimension and time delay. An embedding dimension determines the number of inputs of each component fuzzy system and a time delay decides the interval of inputs of the time series. According to the embedding dimension and the time delay, the component fuzzy system takes various input-output pairs. The PSFS determines the final predicted value as an average of all the outputs of the component fuzzy systems in order to reduce error accumulation effect.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.1-7
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• 2018

A combustion test for a supersonic combustor was conducted using a direct-connected type supersonic combustor test facility. The facility was verified for the capability of simulating required flow conditions. The test condition was maintained at Mach 2.0, $915^{\circ}C$ and 496 kPa for 15 s. Using gaseous hydrogen as the fuel, the combustor model was also tested for its ignition and flame holding capability at the fuel equivalence ratio of 0.12. Combustion efficiency was 71%, and the supersonic flow regime was obtained at this test condition.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.1
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• pp.64-70
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• 2014

In this paper, the new LLCL filter is proposed for grid connected three-phase PWM inverter for passive damping. LLCL filter inserts a small inductor in the branch of the capacitor of the traditional LCL filter to compose a series resonant circuit to reduce the switching-frequency component on grid current. Using LLCL filter, the switching-frequency current ripple components can be attenuated much better than the LCL filter, leading to a decrease in the total inductance. However, the resonance phenomena caused by zero impedance from the addition of LC branch in LLCL filter can be a big problem. Resonance phenomena of LLCL filter can be a source of grid system instability, so proper damping methods are required. However, it is difficult to apply a passive damping method in the conventional LLCL filter, because the damping resistor increase impedance of the LC branch. Therefore, switching frequency component of grid current can not much attenuated by low Q of LC series resonance effect. In this paper, a new LLCL filter is proposed to overcome the conventional LLCL filter with passive damping. The validity of the proposed method is proven by simulation and experimental result.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.11
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• pp.188-194
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• 2013

In this paper, we proposed a new method for pulmonary vessels image segmentation and refinement from pulmonary image. Proposed method consist of following five steps. First, threshold estimation is performed by polynomial regression analysis of histogram variation rate of the pulmonary image. Second, segmentation of pulmonary vessels object is performed by density-based segmentation method based on estimated threshold in first step. Third, 2D connected component labeling method is applied to segmented pulmonary vessels. The seed point of both side diaphragms is determined by eccentricity and size of component. Fourth step is diaphragm extraction by 3D region growing method at the determined seed point. Finally, noise cancelation of pulmonary vessels image is performed by 3D connected component labeling method. The experimental result is showed accurately pulmonary vessels image segmentation, the diaphragm extraction and the noise cancelation of the pulmonary vessels image.

• Journal of the Korean Institute of Intelligent Systems
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• v.10 no.2
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• pp.113-121
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• 2000

This paper presents a parallel-structure fuzzy system(PSFS) for prediction of time series data. The PSFS consists of a multiple number of fuzzy systems connected in parallel. Each component fuzzy system in the PSFS predicts the same future data independently based on its past time series data with different embedding dimension and time delay. The component fuzzy systems are characterized by multiple-input singleoutput( MIS0) Sugeno-type fuzzy rules modeled by clustering input-output product space data. The optimal embedding dimension for each component fuzzy system is chosen to have superior prediction performance for a given value of time delay. The PSFS determines the final prediction result by averaging the outputs of all the component fuzzy systems excluding the predicted data with the minimum and the maximum values in order to reduce error accumulation effect.

• Journal of the Korea society of information convergence
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• v.1 no.1
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• pp.1-8
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• 2008

If the management through the center server is unnecessary and JXTA is connected to a network, a communication with any kind of devices or some device is possible. And features that a communication with heterogeneous P2P systems is possible have. The important module of the designed Data exchange system an interworking between the P2P system which it is made we used API and the each other different protocol the possible data for replacement Data exchange system were designed this kind of a feature was to the utmost utilized may account for the XML Parser Component(XPC) which we use it parses the or about a request and the generated request, and the structure of the XML Making Component(XMC) which we use in generating the inappropriate a request and response.

• Current Optics and Photonics
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• v.3 no.6
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• pp.502-509
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• 2019

Based on the typical pixel structure and parameters of a polysilicon uncooled bolometer, the absorption rate of a polysilicon microbridge infrared detector for 10.6 ㎛ laser energy was calculated through the optical admittance method, and the thermal coupling model of a polysilicon microbridge component irradiated by far infrared laser was established based on theoretical formulas. Then a numerical simulation study was carried out by means of finite element analysis for the actual working environment. It was found that the maximum temperature and maximum stress of the microbridge component are approximately exponentially changing with the laser power of the irradiation respectively and that they increase monotonically. The highest temperature zone of the model is gradually spread by the two corners of the bridge surface that are not connected to the bridge legs, and the maximum stress acts on both sides of the junction of the microbridge legs and the substrate. The mechanism of laser-induced hard damage to polysilicon detectors is the melting damage caused by high temperature. This paper lays the foundation for the subsequent study of the interference mechanism of the laser on working state polysilicon detectors.