This study investigated variables for improving adhesive strength using laser surface treatment when bonding dissimilar materials using adhesives. adhesive strength analysis was performed for CFRP and Al6061 by laser irradiation intensity, and surface roughness was measured to analyze the related results. In the case of CFRP, the adhesive strength was good when the surface was not treated. In the case of Al6061, the adhesive strength was 25 MPa when the surface was treated with 20W, the maximum output of the laser surface treatment equipment, and the adhesive strength was improved by 125% compared to the untreated specimen. In addition, by measuring the surface roughness in the experiment, it was confirmed that the higher the surface roughness, the better the adhesive strength.

본 연구는 초고강도 콘크리트판, 그라우팅 및 모체 콘크리트 내에 후크와 스터드로 연결한 합성접합부의 전단 실험 을 수행하고 그 거동을 파악하고자 한다. 압축강도 35 MPa, 50 MPa 및 90 MPa 그라우팅의 강도, 4종류의 전단연결재 배치를 실험변수로 총 12개의 시험체를 제작하였다. 합성접합부의 전단력은 그라우팅 콘크리트의 압축강도에 따라 비례적 관계를 가지 고 있다. 휨모멘트가 지배적인 힘이 아니고 면적이 크며 서로 다른 시기에 콘크리트를 친 경계면 합성체에서 콘크리트 전단력 은 무시할 정도 크기가 아니다. 콘크리트 모체 압축강도보다 그라우팅의 압축강도가 크다면 접합부에서 콘크리트 전단력이 유 의미하게 크며 전단연결재를 병용하면 더 큰 전단력을 얻을 수 있다.

The bead geometry according to the welding conditions was analyzed through the laser fillet welding experiment of 9% Ni steel, and the relationship between the shear strength and the five bead geometry measured by selecting the main bead geometry of the fillet weld was analyzed. Among the welding conditions, the welding conditions that directly affect the penetration depth are welding speed and laser power, and the working angle and beam position have a great influence on the formation of leg of vertical and horizontal members. The bead shape, which greatly affects the shear strength, is the horizontal member length, neck thickness, and weld length, and has a proportional relationship with the shear strength. As a result of confirming the relationship between shear strength and bead shape through the derivation of the trend line, it was confirmed that the length of the vertical member, whose R2 value was 0.92, was most closely related to the shear strength.

최근 국내에서는 고층 벽식 아파트 건설 시, 하부 주차공간과 공용공간 확보를 위하여 RC 전이슬래브 시스템을 사용하는 경우가 증가하고 있다. 하지만 두께가 얇은 RC 무량판 슬래브를 위해 개발된 설계방법 및 구조성능평가 방법을 두께가 매우 두꺼운 전이슬래브 구조설계에 그대로 사용하고 있다는 문제점이 있다. 따라서 합리적인 전이슬래브의 구조설계를 위해서는 RC 전이슬래브 시스템의 2면 전단거동 양상에 대한 명확한 분석이 필요하다. 이에 따라 본 연구에서는 전이슬래브의 두께, 콘크리트 강도, 전단경간비, 철근비 등 다양한 설계변수에 따라 비선형 FEM을 이용하여 전이슬래브의 2면 전단거동을 분석 하였다. 또한 비선형 FEM 해석결과와 기존의 2면 전단강도 평가식으로 예측한 전단강도를 비교분석하여 기존 평가식의 전이슬래브 2면 전단강도 평가 유효성을 검토하였다.

This study has assessed mechanical bonding strength of lead-free solder joint. Assessment methods was performing long-term reliability test about thermal shock, thermal life and high temperature & high humidity. Based on the results of analyzing mean values that was obtained from repetion of 5 times according to each conditions, reduction of mechanical bonding strength of each tests was confirmed. When it comes to HB chip, the order of high deviation rate was shown thermal shock, high temperature & humidity and thermal life. And the higher deviation rate of R0 is high temperature & humidity, thermal life and thermal shock. The order of high deviation rate of C1 chip is high temperature & humidity, thermal shock and thermal life. Related to this result of experiment, the most stable error range of mechanical bonding strength is established. From now on optimized quantity of solder and shape of solder-joint is needed by establishing a test method which can make error range of mechanical bonding strength minimize.

In the moment frame subjected to earthquake loads, beam-column joint is structurally important for ductile behavior of a system. ACI Committee 352 proposed guidelines for designing beam-column joint details. The guidelines, however, need to be updated because of the lack of data regarding several factors that may improve the performance of joints. The purpose of this study is to investigate the seismic performance of reinforced concrete exterior joints with high-strength materials and unbonded tendons. Three specimens with different joint shear demand-to-strength ratios were constructed and tested, where headed bars were used to anchor the beam bars into the joint. All specimens showed satisfactory seismic behavior including moment strength of 1.3 times the nominal moment, ductile performance (ductility factor = at least 2.4), and sufficiently large dissipated energy.

In this study, the cold rolled DP590 FSW joints were obtained by the position control type of the FSW machine and examined. The FSW weldability was investigated using the Si3N4 tool specially made by Cold Isostatic Press (CIP). Defect-free joints were formed at 180-300 mm/min at 800 rpm. However, a groove-like defect was observed along the joint line of the advancing side due to the insufficient material flow. In addition, the life of the Si3N4 tool was compared to that of the polycrystalline cubic boron nitride (PCBN) tool for the durability. The SI3N4 tool that was broken in which tool reached a length of 5 m and around half of the performance level of the PCBN tool.

The effects of printed circuit board electroless nickel immersion gold (ENIG) and organic solderability preservative (OSP) surface finishes on the electromigration reliability and shear strength of Sn-3.5Ag Pb-free solder bump were systematically investigated. In-situ annealing tests were performed in a scanning electron microscope chamber at 130, 150, and 170˚C in order to investigate the growth kinetics of intermetallic compound (IMC). Electromigration lifetime and failure modes were investigated at 150˚C and 1.5×105A/cm2, while ball shear tests and failure mode analysis were conducted under the high-speed conditions from 10 mm/s to 3000 mm/s. The activation energy of ENIG and OSP surface finishes during annealing were evaluated as 0.84 eV and 0.94 eV, respectively. The solder bumps with ENIG surface finish showed longer electromigration lifetime than OSP surface finish. Shear strengths between ENIG and OSP were similar, and the shear energies decreased with increasing shear speed. Failure analysis showed that electrical and mechanical reliabilities were very closely related to the interfacial IMC stabilities.

For the artistic column used by Glass Fiber Reinforced Plastic(GFRP), the connection of steel with GFRP were needed. Due to the fabricating characteristics of hand laminating, GFRP surfaces had to be connected. Because there were no existed data of these connection, experimental study has to be followed so that the structural strength and buckling mode could be investigated. In this paper, therefore, the axial tests of steel with GFRP were performed. The connection of GFRP's surfaces could be also tested as well. As a result, it could be figured out that the strength of these connections were determined by the adhesive strength.

알루미늄 폼을 볼트나 너트를 이용하여 체결한다면 경량성이 감소되므로 접착제로 접합하는 것이 가 장 효율적이다. 이런 알루미늄 폼 접착 구조물에 대한 충격 피로 특성과 접착 합면에 대한 파괴인성 연 구는 매우 부족하며 또한 중요하다. 이에 따라 본 연구에서는 알루미늄 폼으로 만들어진 DCB모델을 접 착제로 접합한 후 두께를 변수로 하여 25mm 부터 45mm까지 10mm차이를 두어 실험과 컴퓨터 시뮬레 이션을 통하여 수행하였다. 실험은 MTS사의 인장 시험기를 사용하여 강제 변위 100mm를 주어 변위에 따른 전단력을 알아보았고, 실험과 똑같은 조건하에 ANSYS를 이용하여 유한요소해석을 수행하였다. 실험과 유한요소해석 값을 비교하여 접착제로 접합된 알루미늄 폼 구조물의 접착 합면에 대한 파괴인성을 고찰하였다.

Aluminum foam has many superb properties such as light weight, impact absorption and thermal resistance by comparing with original metallic materials. Composite materials made of aluminum foam have used at various fields as automotive bumper, shock absorption, vessel and aircraft. But it is inefficient to join aluminum foam with bolt and nut because of the property of light weight. In this study, this approach is investigated by joining aluminum foam with adhesive. Impact fatigue and failure toughness at the commissure of adhesive structure are studied by simulation analysis. This study aims to investigate the shear strength evaluation at shear mode of adhesively bonded joint with double cantilever beam(DCB) made of aluminum foam.

Existing non-destructive test for evaluation of concrete compressive strength may show deviation in results analysis due to deterioration of precision by strength calibration and dry or humid condition by age, so there needs be testing method to determine long term structural internal force by collecting specimen with no damage of structure and measuring compressive strength through destruction test. This research applied to mock-up member the compressive strength evaluation method using joint separation mold that can plan and produce specimen cured in the same composition environment as concrete structure by attaching arbitrary(joint separation) to the form before concrete piling, and as a result, the management specimen was contrary to the hydration temperature of the member or was affected by external atmospheric temperature, however the joint separation specimen connected to structure and managed in the same environment showed a temperature curve similar to the member and decrease in temperature difference. Additionally, from initial age, with the compressive strength of joint separation specimen most similar to core strength，stable compressive strength can be evaluated up to design criteria strength 100MPa, so the method is proposed as an evaluation technique that can confirm highly reliable concrete quality.

An evaluation of the concrete strength has very important meaning in the maintenance and the structural safety. The reliability of ferroconcrete building is weakening and enlarging the life is strongly demanded due to the early deterioration of concrete. Like this social demand, concrete strength presumption is being indirectly executed using the result in parallel with the concrete pouring by material age. This data is usually different as concrete poured practically and the way of hardening and curing. Although existing concrete strength presumption formula is proposed, the material used and the concrete strength is different. And as a matter of remicon, the concrete strength varies according to the site and the way of curing. So the objective of this research is strength evaluation of the structural body concrete according to the concrete pouring and curing temperature change seasonally after using the system which evaluates the structural body concrete strength which is applied the transparent junction-separation mold that is presented. Also there is an objective to present the fundamental data for the constructional quality technique proposal of the structural body concrete developed in relation to field specimen and the strength evaluation method by non-breaking.

TFT-LCD is the most popular type of flat display panel in the information technology field. The back light unit is a main part of the structure of a TFT-LCD panel. Occasionally, studies have shown that failures of the CCFL of the BLU occur due to the poor weld characteristics of these materials. The aim of this study was to prepare some technical data and to characterize a microjoined electrode for the CCFL. Microstructure examinations, microhardness measurements, resistance measurements and microtensile tests of the microjoined electrode were carried out. The result indicates that a large amount of grain coarsening exists in the heat-affected zone (HAZ) of the weld between the cup and the pin. This grain coarsening of the HAZ between the cup and pin is caused by the welding cycle, which may have an influence on the lowest microhardness values. Fracturing of the microjoined electrode also occurred at the HAZ close to the cup between the weld holding the cup and the pin. Additionally, no specific changes of the electrical resistance among the cup, pin, and lead wire themselves or in the microjoined electrode were observed.

The micro-structural changes, strength characteristics, and micro-fractural behaviors at the joint interface between a Sn-4.0wt%Ag-0.5wt%Cu solder ball and UBM treated by isothermal aging are reported. From the reflow process for the joint interface, a small amount of intermetallic compound was formed. With an increase in the isothermal aging time, the type and amount of the intermetallic compound changed. The interface without an isothermal treatment showed a ductile fracture. However, with an increase in the aging time, a brittle fracture occurred on the interface due mainly to the increase in the size of the intermetallic compounds and voids. As a result, a drastic degradation in the shear strength was observed. From a microshear test by a scanning electron microscope, the generation of micro-cracks was initiated from the voids at the joint interface. They propagated along the same interface, resulting in coalescence with neighboring cracks into larger cracks. With an increase in the aging time, the generation of the micro-structural cracks was enhanced and the degree of propagation also accelerated.

본 논문에서는 지진하중을 받는 내부 및 외부 철근콘크리트 보-기둥 접합부의 강도 및 연성능력을 평가하였다. 접합부에 인접한 보에 소성힌지가 발생한 이후 접합부가 파괴할 경우 접합부 내력은 보의 소성힌지의 영향을 받아 감소하게 된다. 보에 소성힌지가 발생하면 보의 부재축방향 변형률은 급격하게 증가하게 되며, 증가된 부재축방향 변형률은 접합부의 변형에 영향을 주어 접합부의 강도를 저감시킨다. 이 논문에서는 보에 소성힌지가 발생하기 이전에 파괴하는 접합부의 내력과 보에 소성힌지가 발생한 이후에 파괴하는 접합부의 연성능력을 접합부의 변형능력 및 스트럿의 강도저감을 이용하여 평가하였다. 제시한 평가법은 52개의 접합부 실험체를 이용하여 검증하였다.

보 플랜지 절취형(Reduced Beam Section, RBS) 내진 철골모멘트접합부는 국내외의 여러 실험프로그램에서 뛰어난 내진성능을 보여 주었다. 그러나 추가적으로 규명해야할 설계상의 몇몇 이슈들이 아직 남아있다. 그 중의 하나가 패널존의 보에 대한 적정강도이다. 다수의 실험결과가 존재함에도 불구하고 패널존과 보 사이의 적정강도비가 아직까지 명확하게 제시된 바가 없다. 본 연구에서는 독립적으로 수행된 국내외의 광범위한 실험 데이터베이스를 기초로 패널존 강도가 접합부의 내진거동에 미치는 영향을 포괄적으로 분석하였다. 이를 기초로 보의 좌굴을 감소시키는 동시에 충분한 접합부 소성회전능력을 보장할 수 있는 균형패널존의 강도범위를 제안하였다. 아울러 반복재하 실물대 실험결과를 만족스럽게 재현할 수 있는 유한요소모델을 구축한 후 다양한 수치해석을 통하여 실험자료에서 누락된 부분이나 실험적으로는 파악하기 어려운 거동을 고찰하였다. 이 과정에서 오늘날의 강력한 유한요소해석기법을 활용하여 많은 비용이 드는 철골접합부 실물대 내진실험을 보완하거나 적어도 부분적으로 대체할 수 있음을 확인하였다.

본 연구는 8개의 RBS(reduced beam section) 내진 철골모멘트접합부의 실물대 실험결과를 요약한 것이다. 실험의 주요변수는 보 웨브 접합법 및 패널존 강도를 택하였다. 균형 패널존 시험체는 접합부의 내진성능을 감소시키지 않으면서, 보와 패널존이 함께 균형적으로 지진에너지를 소산시키도록 설계하여 값비싼 패널존 보강판(doubler plates)의 수요를 줄이고자 시도한 것이다. 보 웨브를 용접한 시험제는 모두 특별 연성모멘트골조에서 요구되는 접합부 회전능력을 충분히 발휘하였다. 반면 보 웨브를 볼트 접합한 시험체는 조기에 스캘럽을 가로지르는 취성파단이 발생하는 열등한 성능을 보였다. 보 그루브 용접부 자체의 취성파괴가 본 연구에서와 같이 양질의 용접에 의해 방지되면, 스켈럽 부근의 취성파단이 다음에 해결해야 할 문제로 대두되는 경향을 보인다. 보 웨브를 볼팅한 경우에 접합부 취성파단의 빈도가 월등히 높은 이유를 실험 및 해석결과를 토대로 제시하였다. 측정된 변형도 데이터에 의할 때, 접합부의 전단력 전달메카니즘은 흔히 가정하는 고전 휨이론에 의한 예측과 전혀 다르다. 이는 전통적 보 웨브 설계법을 재검토할 필요가 있음을 시사하는 것이다. 아울러, 접합부에서 요구되는 바람직한 거동기준을 제시하고 이를 근거로 균형 패널존의 강도범위에 대한 예비적 추정치를 제시하였다