• 대한치과기공학회지
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• 제33권4호
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• pp.339-347
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• 2011

Purpose: This study was investigated the bonding strength of two kinds of Ni-Cr alloy with respect to the condition of surface treatment. Methods: The surface treatment was performed on the two kinds of Ni-Cr alloy (B alloy and R alloy) specimens, which were sandblasted with $50{\mu}m$, $110{\mu}m$, and $250{\mu}m$ aluminium oxide and were treated with opaque application (paste and wash opaque). The roughness on the surfaces of the specimens was observed. The metal-ceramic interfaces were analyzed with EPMA in order to ionic diffusion, and the shear test was performed. Results: The BA250 specimen, which has higher surface roughness, showed the highest bonding strength in B specimens. In R specimens, the bonding strength of RA110 specimen was the highest. Conclusion: B specimen formed a mechanical bond between metal-ceramic interfaces; however, in the case of R specimen, a chemical bond was formed between that interfaces. There was no significant statistical difference between the bonding strengths of two types of specimens (p>0.05).

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.571-576
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• 1994

In recent years, ultrasonic has been widely applied in measurement and industrial fields and its application range has been expanded as a result of continuous research and development. Wire Bonding Machine, an instrument fabricating semi-conductor, makes use of ultrasonic bonding method. In order to improve the currently used wire bonding machine using ultrasonic energy, technical accumulation is needed steadily through development of exciting device of ultrasonic composed of piezoelectic vibrator and horn. This study investigates the design conditions affecting the dynamic characteristics through the theoretical and experimental analysis of piezoelectric vibrator and horn, The study conducts separately the system identification of piezoelectric vibrator in time domain and the modal analysis of horn in frequency domain. In theoretical model, the integrated modeling is conducted via a combination of dynamic identification of piezoelectric vibrator and theoretical analysis of horn. Hence comparison is made for theoretical and experimental results of the dynamic characteristics of the ultrasonic transducer composed of piezoelectric vibrator and horn. Form the results of this study we develop the design technique of ultrasonic transducer using dynamic characteristic analysis and propose the possibility of ultrasonic welding considering the optimal condition of the natural frequency and vibration mode of horn.

• 화약ㆍ발파
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• 제17권4호
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• pp.32-50
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• 1999

This study deals with interface charactristics of tube and tubesheet of the nuclear steam generator by the explosive expansion in order to take advantage of optimum expansion ratio, pull-out strength and leakage tightness and improvement of the resisitance on the stress corrosion cracking for low residual stress. The paper also show the relationship between roll, hydraulic and explosive expansion. The results obtain are as follows (1) Because of the explosive bonding is to use the high speed pressure and energy by the explosive, workability is good, bonding region is homogenous (2) Expansion ratio is 2.7%, Pull-out strength 850kg, Leakage strength $500kg/cm^2$. Clearance gap is 10~30mm in case of explosive expansion and interface structure of the tube and tubesheet is optimum condition. (3) As the transition region of the explosive expansion is inactive, the resistance of the stress corrosion cracking is increases 30~40% compare to the roll and hydraulic expansion.

• Journal of Welding and Joining
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• 제17권2호
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• pp.104-111
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• 1999

The interfacial microstructure and bond strength were examined for WC-Co/Cu/SM45C steel join using a nickel-plated copper in vacuum at 1323K for 0.6ks∼3.6ks. After bonding, microstructure in bonding interface was observed by OM(Optical Microscopy), SEM(Scanning Electron Microscopy) and EPMA(Eelectron Probe Micro Analyzer). The oil cooling was carried out at 353K, the cooling rate in air and furnace was 22K/s and 4.4K/s. respectively. It was found that dendritic widths increased with the content of cobalt and bonding times at 1323K. As a whole, bond strength values at the same bonding condition decreased in this order: WC-13wt.%Co/SM45Csteel. WC-8wt.%Co/SM45Csteel and WC-4wt.%Co/SM45Csteel. The bond strength of WC-13wt.%Co/S45C steel joint in oil cooling was 273MPa. This value was greatly higher than those of 125MPa in furnace cooling and 93MPa in air cooling at 1323K for 0.6ks. The bond strength values were found to be closely associated with the content of cobalt in WC-Co and cooling rate.

• Geomechanics and Engineering
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• 제18권2호
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• pp.133-140
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• 2019

Strain-rate and temperature have significant effects on the one-dimensional (1D) compression behavior of soils. This paper focuses on the bonding degradation effect of soil structure on the time and temperature dependent behavior of soft structured clay. The strain-rate and temperature dependency of preconsolidation pressure are investigated in double logarithm plane and a thermal viscoplastic model considering the combined effect of strain-rate and temperature is developed to describe the mechanical behavior of unstructured clay. By incorporating the bonding degradation, the model is extended that can be suitable for structured clay. The extended model is used to simulate CRS (Constant Rate of Strain) tests conducted on structural Berthierville clay with different strain-rates and temperatures. The comparisons between predicted and experimental results show that the extended model can reasonably describe the effect of bonding degradation on the stain-rate and temperature dependent behavior of soft structural clay under 1D condition. Although the model is proposed for 1D analysis, it can be a good base for developing a more general 3D model.

• Design & Manufacturing
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• 제17권1호
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• pp.40-47
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• 2023

Macular degeneration and glaucoma are representative age-related retinal diseases that rank second and third in the prevalence of retinal diseases, and are a kind of degenerative neurological disease. Irreversible visual acuity and visual field damage may occur, and the number of patients is rapidly increasing as the population ages. Since this retinal disease is a chronic disease, continuous drug treatment is required. There are various drug delivery methods for treatment, but direct injection of the drug into the intravitreal is the most effective for continuous delivery of the drug over a long period of time. In order to solidify Dexamethasone, a retinal disease treatment, and insert it into the primary intravitreal, it is important to develop a technology to miniaturize the treatment and an applicator to deliver the treatment. In this study, a mold technology was developed to integrate the cannula and hub, which are one part of applicator. In addition, surface treatment was performed on the outside of the cannula to improve the bonding strength between the cannula and the hub, and the bonding strength according to each condition was analyzed through a tensile test.

• Journal of the Korean Wood Science and Technology
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• 제44권3호
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• pp.315-322
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• 2016

2개 이상의 보부재 집성재 요소들의 측면접착으로 제작된 "블록접착집성재"는 대단면 목조건축물의 건축부재로 활용 가능한 구조용재다. 블록접착집성재의 측면은 접착제의 종류와 도포량 및 압체압력을 각기 다른 조합으로 접착하여 박리시험과 전단블록시험으로 접착성능을 검토하였다. 실험결과 레조시놀접착제 $500g/m^2$을 도포하고 압체압력 1.5 MPa의 조건으로 제작된 블록접착집성재의 측면접착성능이 가장 양호하였다. 양호한 측면접착조건으로 제작된 블록접착집성재는 동일단면계수의 대조군 집성재와 휨 강도 성능을 비교 검토하였다. 블록접착집성재의 휨 탄성계수는 대조군 집성재와 유사하였으며, 파괴계수는 대조군집성재 보다 27% 향상되었다. 할렬은 대조군집성재 보다 블록접착집성재에서 다량 발생하였으며, 블록접착집성재의 측면접착층에서 계면파괴나 응집파괴는 관찰되지 않았다.

• 대한치과기공학회지
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• 제38권3호
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• pp.175-183
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• 2016

Purpose: Observation of Oxide Film Formation and Bonding Strength according to surface treatment of Co-Cr Alloy for porcelain fused to Metal. Methods: metal specimens $0.5mm{\times}25mm{\times}4mm$ in size were made using Co-Cr alloys for porcelain fused to metal crown (Heraenium P, Tae jung Medis). Dental porcelain $0.5mm{\times}25mm{\times}4mm$ in size was sintered on the metal specimens after changing the etching time, sandblasting condition, and heat treatment temperature. Subsequently, the bonding strength was compared by the three-point flexural strength test using a universal testing machine (UTM) to observe the fracture surface and oxidized layers. Results: With regard to the experimental group treated with acid-etching, Specimen 1 treated for 25 minutes (B-3) showed the highest bonding strength, and Specimen 2 treated only with sandblasting showed the most excellent bonding force at 3.5 bar (C-3). With regard to the experimental group treated with sandblasting at 3.5 bar after acid-etching for 25 minutes, Specimen 3 with heat treatment at $980^{\circ}C$ (D-3) showed the highest bonding strength. Conclusion: The specimen which went through both sandblasting and etching, showed an excellent ceramicmetal bond strength.

• 한국기계가공학회지
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• 제20권5호
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• pp.135-141
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• 2021

As a trend of lightening automobiles and electronic products, several studies are currently underway to replace parts of metals with resins. In particular, heterojunctions between metals and resins are now under the spotlight. This study aims to evaluate the variation in bonding strength with process conditions when the polybutylene terephthalate (PBT) polymer is bonded to a specimen of the lightweight 6061 aluminum alloy (AL6061). Conditions of the bonding surface of the AL6061 specimen, the temperature of the injection mold, and the content of the glass fiber were considered to be process variables. Bonded specimens were manufactured for different values of these variables. Bonding strength tests were then performed on these specimens and variations were analyzed in their characteristics corresponding to those of the process conditions. Fractures in these specimens were assessed using scanning electron microscopy (SEM) to assess the fracture surface. This was then used to analyze the fracture shape and determine whether anodizing the specimen led to the development of cracks on the joint surface. Results of the above test indicated that while the surface condition of the specimen and the temperature of the injection mold significantly influenced the strength of bonding, the content of the glass fiber did not.

• 한국항공우주학회지
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• 제50권7호
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• pp.455-463
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• 2022

세계 각국에서는 위성용 카메라 등 고신뢰성을 요구하는 카메라에 대한 연구개발 필요성이 높아짐에 따라 시편시험 수행을 통해 광기구 구조물과 광학부품 간 접착강도 물성치의 신뢰성을 확보해오고 있다. 다만 널리 활용되고 있는 시편형상은 취성 경향이 높은 유리 및 유리세라믹 소재에의 적용에 적합하지 않아 접착강도 한계값 도달 전 유리 부분 응력집중으로 인한 소재 자체 깨짐 현상이 정확한 접착강도 획득에 어려움을 유발한다. 본 연구에서는 유리 소재 자체 파단이 발생한 시편시험 결과를 바탕으로 다양한 시편형상에 대한 전단시험 환경에서의 응력분포 특성을 해석적으로 분석하였다. 이를 통해 유리부의 응력집중을 완화할 수 있는 형상적 특징을 도출하여 시편시험으로 검증가능한 접착 전단강도의 범위를 개선하였다.