• 비파괴검사학회지
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• 제27권3호
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• pp.224-230
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• 2007

This work is aimed to explore a possibility of using the generalized Lamb waves for nondestructive evaluation of the bonding quality of layered substrates. For this purpose, we prepared two sets of specimens with imperfect bonding at their interfaces; 1) TiN-coated specimens with various wear conditions, and 2) CVD diamond specimens with various cleaning conditions. A dispersion simulation performed for layered substrates with imperfect interfaces are carried out to get the characteristics of dispersion curves that can be used for bonding quality evaluation. Then the characteristics of dispersion curves of the fabricated specimens are experimentally determined by use of an ultrasonic backward radiation measurement technique. The results obtained in the present study show that the lowest velocity mode (Rayleigh-like) of the generalized Lamb waves are sensitively affected by the bonding quality. Therefore, the generalized Lamb waves can be applied for nondestructive evaluation of imperfect bonding quality in various layered substrates.

• Advances in Computational Design
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• 제4권1호
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• pp.33-41
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• 2019

In this study, 2-mm Al/Cu bimetallic laminates were produced using asymmetric roll bonding (RB) process. The asymmetric RB process was carried out with thickness reduction ratios of 10%, 20% and 30% and mismatch rolling speeds 1:1, 1:1.1 and 1:1.2, separately. For various experimental conditions, finite element simulation was used to model the deformation of bimetallic Al/Cu laminates. Specific attention was focused on the bonding strength and bonding quality of the interface between Al and Cu layers in the simulation and experiment. The optimization of mismatch rolling speed ratios was obtained for the improvement of the bond strength of bimetallic laminates during the asymmetric RB process. During the finite element simulation, the plastic strain of samples was found to reach the maximum value with a high quality bond for the samples produced with mismatch rolling speed 1:1.2. Moreover, the peeling surfaces of samples around the interface of laminates after the peeling test were studied to investigate the bonding quality by scanning electron microscopy.

• 한국연소학회지
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• 제22권3호
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• pp.47-52
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• 2017

The propellant tile and crack which account for the greatest proportion of solid rockets are profoundly affected by viscosity and mechanical properties of solid propellant. In this paper HTPB/AP/Al system propellant has been researched for the viscosity, mechanical properties and burning properties with type and contents of bonding agents. The viscosity of propellant was changed significantly depending on the type and contents of bonding agents, and mechanical properties of HTPB/AP/Al system propellant were also varied. Considering both lower viscosity and stable mechanical properties, the optimum type and contents of bonding agents can be identified as the main factors to the HTPB/AP/Al system propellant.

• 품질경영학회지
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• 제49권3호
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• pp.255-268
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• 2021

Purpose: We sought to understand why a high-speed rotating projectile featuring a fuze-and-body assembly sometimes exhibited airburst, and we intended to improve the flight stability by eliminating airburst. Methods: We performed characteristic factor analysis, structural mechanics modeling, and dynamic modeling and simulation; and we scheduled firing tests to discover the cause of airburst. We used a step-by-step procedure to analyze the reliability function for selecting the bonding force standard that prevents airburst. Results: The 00MM high-speed rotating projectile features a fuze bonded to a body assembly; the bonding sometimes can break on firing. The resulting contact force, vibration and roll damping during flight generated yaw. Flight became unstable; fuze operation triggered an airburst. Our reliability test improved the bonding force standard (the force was increased). When the bonding force was at least the minimum required, a firing test revealed that airburst/flight instability disappeared. Conclusion: Analysis and identification of the causes of flight instability and airburst render military training safer and enhance combat power. Ammunition must perform as designed. Our method can be used to set standards that improve the performances of similar types of ammunition.

• 반도체디스플레이기술학회지
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• 제23권2호
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• pp.135-142
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• 2024

Cu-Cu bonding, one of the key technologies in advanced packaging, enhances semiconductor chip performance, miniaturization, and energy efficiency by facilitating rapid data transfer and low power consumption. However, the quality of the interface bonding can significantly impact overall bond quality, necessitating strategies to quickly detect and classify in-process defects. This study presents a methodology for detecting defects in wafer junction areas from Scanning Acoustic Microscopy images using a ResNet-50 based deep learning model. Additionally, the use of the defect map is proposed to rapidly inspect and categorize defects occurring during the Cu-Cu bonding process, thereby improving yield and productivity in semiconductor manufacturing.

• Journal of Welding and Joining
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• 제23권5호
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• pp.55-60
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• 2005

A precise bonding technique, transmission laser bonding using energy transfer, for polymer micro devices is presented. The irradiated IR laser beam passes through the transparent part and absorbed on the opaque part. The absorbed energy is converted into heat and bonding takes place. In order to optimize the bonding quality, the temperature profile on the interface must be obtained. Using optical measurements of the both plates, the absorbed energy can be calculated. At the wavelength of 1100nm $87.5\%$ of incident laser energy was used for bonding process from the calculation. A heat transfer model was applied for obtaining the transient temperature profile. It was found that with the power of 29.5 mW, the interface begins to melt and bond each other in 3 sec and it is in a good agreement with experiment results. The transmission IR laser bonding has a potential in the local precise bonding in MEMS or Lab-on-a-chip applications.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.663-664
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• 2010

• 제어로봇시스템학회논문지
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• 제14권6호
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• pp.543-547
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• 2008

In the paper, we develop the ultrasonic bonding technique for LCD driver chips having small size and high pin-density. In general, the mounting technology for LCD driver ICs is a thermo-compression method utilizing the ACF (An-isotropic Conductive Film). The major drawback of the conventional approach is the long process time. It will be shown that the conventional ACF method based on thermo-compression can be remarkably enhanced by employing the ultrasonic bonding technique in terms of bonding time. The proposed approach is to apply the ultrasonic energy together with the thermo-compression methodology for the ACF bonding process. To this end, we design a bonding head that enables pre-heating, pressure and ultrasonic excitation. Through the bonding experiments mainly with LCD driver ICs, we present the procedures to select the best combination of process parameters with analysis. We investigate the effects of bonding pressure, bonding time, pre-heating temperature before bonding, and the power level of ultrasonic energy. The addition of ultrasonic excitation to the thermo-compression method reduces the pre-heating temperature and the bonding process time while keeping the quality bonding between the LCD pad and the driver IC. The proposed concept will be verified and demonstrated with experimental results.

• 비파괴검사학회지
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• 제12권3호
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• pp.33-39
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• 1992

This paper presents a summary of the immersion ultrasonic test to analyze the quality of diffusion bonding parts. The most important property of diffusion bonding parts is bonding strength, and that can be obtained by shear test. By comparing among data obtained by ultrasonic test(C-Scan) and those by shear test (bonding strength), these data are shown to be in good relation. Therefore ultrasonic C-Scan test result can be used successfully in quantitative quality control for diffusion bonded parts.

• 콘크리트학회논문집
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• 제28권3호
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• pp.329-340
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• 2016

건설 시장에서는 기존의 건물을 철거하거나 보수하는 사례가 늘어나면서 막대한 양의 건설 폐기물이 발생되고 있다. 건설폐기물의 재활용은 자원절약과 환경보전 그리고 건설 산업의 지속적인 발전을 실현하는데 있어서 중요하다. 이에 따라, 폐콘크리트를 파쇄한 후 생산되는 순환 골재의 가치가 환경적, 경제적인 측면에서 대두되고 있다. 순환 골재를 사용한 콘크리트는 일반 골재를 사용한 콘크리트에 비해 성능이 저하한다고 알려져 있고, 성능 저하의 원인은 부착 이질재(시멘트 페이스트 및 모르타르)의 양과 부착 이질재에 내포하는 공극의 양에 따라 좌우된다고 보고되고 있다. 탄산화 메커니즘에 대한 보고에 따르면 탄산화의 진행에 의해 시멘트계 재료의 공극이 충전된다고 알려져 있다. 따라서, 본 연구에서는 순환 골재에 부착한 이질재의 공극 충전에 의한 품질향상을 목표로 하여 탄산화 메커니즘을 기반으로 순환 골재의 부착 이질재 두께에 적합한 최적 탄산화 개질 기간의 추정을 목적으로 한다. 이에 따라, 본 연구에서는 순환 골재의 입도분포에 대한 부착 이질재의 부착율과 부착 두께를 산정하여 부착 이질재를 가정한 모의시험체의 촉진 탄산화 재령에 따른 화학적 정량분석을 통해 재령 경과에 따른 탄산화 깊이를 도출하였다. 또한, 촉진 탄산화 재령과 탄산화 깊이에 대한 상관관계를 바탕으로 부착 이질재 두께에 적합한 순환 골재의 탄산화 개질 추정 기간을 제안하였다.