• Journal of Applied Reliability
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• v.17 no.2
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• pp.150-158
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• 2017

Purpose: The RAM objective is a very important factor that has a great effect on the improvement of the operation ration during the operation maintenance and the reduction of the life cycle cost. It is used as a design criterion during the system development, and its sufficiency should be evaluated during its test evaluation. Method: This study analyzed the cases related to RAM objective setting and suggested the improvement measures. Result: The base data for RAM objective is OMS/MP, which needs to be drawn up under the supervision of the requirement military, and a high-accuracy operating availability should be set through ALDT calculation which reflects the military logistics support environment. In addition, data collection necessary for RAM objective and RAM analysis should be made by supplementing the input data of DELIIS. Conclusion: This study suggests improvement of RAM objective considering for the weapon system.

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.265-266
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• 2008

The environmental and mechanical reliability of planar lightwave circuit (PLC)-type optical splitter modules is investigated with references [1, 3]. The module is composed of Y-branching silica-based waveguides on Si connected to optical fiber with UV-curable adhesives and is packaged in a metal case which is filled with humidity-resistant resin. High optical performance such as low loss, low reflection, and thermal stability are obtained through the use of this fiber connection technique. Ten reliability tests including long-term environmental and mechanical and ALT test were carried out for more then ten $1{\times}32$ channel PLC splitter modules.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.2
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• pp.1-9
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• 2009

Conductive adhesives have recently received a lot of focus and attention from the researchers in electronics industry as a potential substitute to lead-containing solders. Numerous studies have shown that the conductive adhesives have many advantages over conventional soldering such as environmental friendliness, finer pitch feasibility and lower temperature processing. This review focuses on the recent research trends on the reliability and property evaluation of anisotropic and non-conductive films that interconnect the integrated circuit component to the printed circuit board or other types of substrate. Major topics covered are the conduction mechanism in adhesive interconnects; mechanical reliability; thermo-mechanical-hygroscopic reliability and electrical performance of the adhesive joints. This review article is aimed at providing a better understanding of adhesive interconnects, their principles, performance and feasible applications.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.3
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• pp.7-14
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• 2016

High junction temperature directly or indirectly affects the optical performance and reliability of high power LEDs in many ways. This paper is focused on junction temperature characterization of LEDs. High power LEDs (3W) were tested in temperature steps to reach a thermal equilibrium condition between the chamber and the LEDs. The LEDs were generated by pulsed currents with duty ratios (0.091% and 0.061%) in multiple steps from 0mA and 700mA. The diode forward voltages corresponding to the short pulsed currents were monitored to correlate junction temperatures with the forward voltage responses for calibration measurement. In junction temperature measurement, forward voltage responses at different current levels were used to estimate junction temperatures. Finally junction temperatures in multiple steps of currents were estimated in effectively controlled conditions for designing the reliability of LEDs.

• Proceedings of the Korean Reliability Society Conference
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• 2005.06a
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• pp.75-82
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• 2005

In this paper, accelerated life testing(ALT) method and procedures for a are developed and applied to assess the reliability of the product. Relay is a device that can open and close the electric circuit electrically and is used for protecting and controlling the load. In this study, an accelerated life test method for predicting the mechanical life of a relay is developed using the relationship between stresses, failure mechanism and life characteristics of products. Using the ALT method, we performed life tests and analyzed the tests results. The proposed method and procedures may de extended and applied to testing similar kinds of products to reduce test times and costs of the tests remarkably.

• International Journal of Reliability and Applications
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• v.4 no.4
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• pp.183-190
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• 2003

Rail breaks and derailments can cause a huge loss to rail players due to loss of service, revenue, property or even life. Maintenance has huge impact on reliability and safety of railroads. It is important to identify factors behind rail degradation and their risks associated with rail breaks and derailments. Development of mathematical models is essential for prediction and prevention of risks due to rail and wheel set damages, rail breaks and derailments. This paper addresses identification of hazard modes, estimation of probability of those hazards under operating, curve and environmental condition, probability of detection of potential hazards before happening and severity of those hazards for informed strategic decisions. Emphasis is put on optimal maintenance and operational decisions. Real life data is used for illustration.

• Tribology and Lubricants
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• v.21 no.2
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• pp.71-76
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• 2005

This paper compares of mechanical tensile properties of 6 kinds of copper foil. The beam lead made with copper foil. Different from other package type such as plastic package, Chip Size Package has a reliability problem in beam lead rather than solder joint in board level. A new tensile loading system was developed using voice-coil actuator. The new tensile loading system has a load cell with maximum capacity of 20 N and a non-contact position measuring system based on the principle of capacitance micrometry with 0.1nm resolution for displacement measurement. Strain was calculated from the measured displacement using FE analysis. The comparison of mechanical properties helps designer of package to choose copper for ensuring reliability of beam lead in early stage of semiconductor development.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.276-278
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• 2007

Many processes have been introduced to join PE pipes, but most of these methods have lots of disadvantages such as costs and lack of reliability, etc. Recently due to the benefits of cost, safety and reliability, the but welding has been paid much attention to join PE pipes. In case of butt welding, the heat plate which is used to melt PE pipes is the most critical equipment. In this study, after designed secondary developed heat plate of new shape, the PE double wall pipes were but-welding by using the developed heat plate and secondary developed heat plate and comparison of weld-zones and tensile test were performed. As results of tensile test, tensile strengths using secondary developed heat plate were measured higher $1.17{\sim}1.5$ than using developed heat plate.

• Current Photovoltaic Research
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• v.10 no.4
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• pp.111-115
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• 2022

For the high efficiency of the photovoltaic module, a high-output solar cell, which is the basis of photovoltaic power generation, is required. As the light receiving area of the solar cell increases, the light receiving area of the photovoltaic module also increases. Accordingly, recent trend is to use large-area solar cells such as M6 and M8 instead of M2-based solar cells for manufacturing the photovoltaic module and a study on the mechanical stiffness of the module with increased size is required. In this study, a mechanical load test corresponding to IEC-61215 was performed among the reliability tests of large-area photovoltaic modules. In order to confirm the degree to which the mechanical load test affects the photovoltaic module, the output and EL images were checked by sequentially increasing the pressure by 600 Pa at a pressure of 2400 Pa. Also, factors such as output and efficiency of large-area photovoltaic modules were verified through mechanical load testing of actual large-area photovoltaic modules and the rate of change was very small at 1%.

• Structural Engineering and Mechanics
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• v.42 no.2
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• pp.175-189
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• 2012

This paper presents an algorithm for structural reliability with the response surface method. For this aim, an approach with three stages is proposed named as improved response surface method. In the algorithm, firstly, a quadratic approximate function is formed and design point is determined with First Order Reliability Method. Secondly, a point close to the exact limit state function is searched using the design point. Lastly, vector projected method is used to generate the sample points and Second Order Reliability Method is performed to obtain reliability index and probability of failure. Five numerical examples are selected to illustrate the proposed algorithm. The limit state functions of three examples (cantilever beam, highly nonlinear limit state function and dynamic response of an oscillator) are defined explicitly and the others (frame and truss structures) are defined implicitly. ANSYS finite element program is utilized to obtain the response of the structures which are needed in the reliability analysis of implicit limit state functions. The results (reliability index, probability of failure and limit state function evaluations) obtained from the improved response surface are compared with those of Monte Carlo Simulation, First Order Reliability Method, Second Order Reliability Method and Classical Response Surface Method. According to the results, proposed algorithm gives better results for both reliability index and limit state function evaluations.