• Title/Summary/Keyword: 접합강도

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Analysis of Variations in the Bonding Strength Characteristics of the AL6061-PBT-Polymer Composite with Injection Parameters (AL6061과 PBT 재료의 인서트 사출공정조건에 따른 접합강도 특성 분석)

  • Jung, Yong-Jun;Kim, Young-Shin;Jeon, Euy-Sik
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.20 no.5
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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.

Interfacial Fracture Toughness Measurement of Composite/metal Bonding (복합재료/금속 접착 계면의 파괴인성치 측정)

  • Kim, Won-Seock;Lee, Jung-Ju
    • Composites Research
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    • v.21 no.4
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    • pp.7-14
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    • 2008
  • Prediction of the load-bearing capacity of an adhesive-bonded Joint is of practical importance for engineers. This paper introduces interface fracture mechanics approach to predict the load-bearing capacity of composite metal bonded joints. The adhesion strength of composite/steel bonding is evaluated in terms of the energy release rate of an interfacial crack and the fracture toughness of the interface. Virtual track closure technique (VCCT) is used to calculate energy release rates, and hi-material end-notched flexure (ENF) specimens are devised to measure the interfacial fracture toughness. Bi-material ENF specimens gave consistent mode II fracture toughness $(G_{IIc})$ values of the composite/steel interface regardless of the thickness of specimens. The critical energy release rates of double-lap joints showed a good agreement with the measured fracture toughness. Therefore. the energy-based interfacial fracture characterization can be a practical engineering tool for predicting the load-bearing capacity of bonded joints.

Characteristics of the Adhesion Layer for the Flexible Organic Light Emitting Diodes (플렉시블 OLED 소자 제작을 위한 접합층 특성 연구)

  • Cheol-Hee Moon
    • Journal of Adhesion and Interface
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    • v.24 no.3
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    • pp.86-94
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    • 2023
  • To fabricate all-solution-processed flexible Organic Light-Emitting Diodes (OLEDs), we demonstrated a bonding technology using a polyethyleneimine (PEI) as an adhesion layer between the two substrates. As the adhesion layer requires not only a high adhesion strength, but also a high current density, we have tried to find out the optimum condition which meets the two requirements at the same time by changing experimental factors such as PEI concentration, thickness of the layer and by mixing some additives into the PEI. The adhesion strength and the electrical current density were investigated by tensile tests and electron only device (EOD) experiments, respectively. The results showed that at higher PEI concentration the adhesion strength showed higher value, but the electrical current through the PEI layer decreased rapidly due to the increased PEI layer thickness. We added Sorbitol and PolyEthyleneGlycohol (PEG) into the 0.1 wt% PEI solution to enhance the adhesion and electrical properties. With the addition of the 0.5 wt% PEG into the 0.1 wt% PEI solution, the device showed an electrical current density of 900 mA/cm2 and a good adhesion characteristic also. These data demonstrated the possibility of fabricating all-solution-processed OLEDs using two-substrate bonding technology with the PEI layer as an adhesion layer.

생쥐 초기 배아에서 Aquaporin 8과 9의 발현에 관한 연구

  • 신현상;계명찬;강수만;이성은;이지원;강한승;김문규
    • Proceedings of the Korean Society of Developmental Biology Conference
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    • 2003.10a
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    • pp.68-68
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    • 2003
  • Aquaporin은 막관통 통로 단백질(transmembrane channel protein)로서, 삼투압의 농도구배에 따라 세포막을 가로질러 물분자를 이동시키는 기능을 하고 있다. 포유류 초기배아에서 포배강 형성은 영양외배엽세포에서 $Na^+ / K^+$ATPase에 의한 이온 농도 구배가 형성되면 auqaporin에 의해 물이 포배강으로 유입되면서 이루어진다. 본 연구에서는 생쥐 초기배아에서 반정량적인 역전사 중합효소 연쇄반응 방법(semi-quantitative RT-PCR)과 실시간 역전사 중합효소 연쇄반응 방법(real-time RT-PCR)을 통하여 AQP8과 9의 mRNA발현을 조사하고 다중 면역형광현미경 방법(confocal immunofluorescence microscopy)을 통해 단백질 발현양상을 분석하였다. AQP8 mRNA는 상실기까지 발현되지 않다가 포배기에 이르러 발현되었고 AQP9 mRNA는 수정란에서부터 발현되어 포배기에는 유의할 정도로 증가하였다. 따라서 AQP8 mRNA는 배아유전자가 활성화되어 나타나는 것이고 AQP9 mRNA는 모계유전자 기원임을 알 수 있었다. AQP8 단백질은 상실배 단계까지 발현되지 않다가 포배시기에 영양외배엽세포사이의 접합면에 발현되었고 AQP9 단백질은 상실배 시기에 할구 사이의 인접 부위에서 강하게 발현되었다가 포배시기에는 세포간의 접합면에 약하게 발현하는 경향을 나타내었다. 실시간 역전사 중합효소 연쇄반응 방법으로 조사한 결과 포배에서 물과 글리세롤을 통과시키는 AQP9는 mRNA의 발현양이 AQP8보다 약 4배 정도 많았다. 또한 포배기에 이르러서야 물만을 통과시키는 AQP8의 발현이 나타나는 것을 보아 포배강 형성시 외부에서 영양외배엽을 통해 포배강으로 유입되는 물의 이동(trans- trophectodermal water movements)에 AQP9보다 AQP8이 더 중요하게 관여할 것으로 사료된다., K, Pb, Cd, Cr, Co, Cu, Ni)을 측정하였다. 실험 조건1의 결과로서 각 국의 유아용 일회용 기저귀의 중금속 함량은 거의 유사한 경향을 나타내었으며 Cr, Zn, Pb, Ni, Mn, Mg, Li, K는 detection limit(2 ppm) 이하였고, Cd, Fe, Co, Cu, Ca, Al, Sr는 검출되었지만 기준치 이하였다. 실험 조건2의 결과로서 측정 항목(Cr, Sb, Cd, Pb, Ni, Co, Cu)중 Cr, Cd, Ni, Cu는 detection limit(0.1 ppm) 이하였고, Sb, Pb, Co는 검출되었지만 기준치 이하였다.았다. 4%의 경우에는 8$0^{\circ}C$이하로 온도를 낮추는 것이 좋은 상태를 나타내었다. 이와 같은 결과는 일반적으로 화학적 레팅을 4%, 7%에서한 선행결과와 상당히 다른 결과이다.염 농도가 증가할수록 감소 현상을 보였다.X>, 75BG30은 8.6$\mu\textrm{m}$, 75BG40은 7.02$\mu\textrm{m}$로 나타났다. 따라서 경화제 양에 관계없이 10$\mu\textrm{m}$ 이하로 나타나, 경화제 10$m\ell$만으로 미세한 크기를 얻을 수 있음을 알 수 있다. 젤리 강도 변화에 따른 차이는 300BF는 78.09$\mu\textrm{m}$ 300BG는 56.32$\mu\textrm{m}$로, 75BF나 75BG에 비하여 현저히 증가하여, 젤라틴의 젤리 강도는 캡슐 제조 조건의 주요한 변수임을 알 수 있다.추출물 투여시 혈당강하 및 혈중콜레스테롤 강하가 나타났으며, 상엽복합추출물 투여와 운동을 병행시 이러한 감소 효과가 더 뚜렷하게 나타났다.교육의 적임자로 보는 시각이 비교적 높았고 약 1/2정도는 영양교육에 참여하겠다는 의지를 가지고 있을 뿐만 아니라 실제로 영양지도를

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Experimental Study on RC Frame Structures with Non-Seismic Details Strengthened by Externally-Anchored Precast Wall-Panel Method (EPWM) (외부 앵커압착형 프리캐스트 벽체로 보강된 비내진 상세를 갖는 철근콘크리트 골조에 대한 실험적 연구)

  • Choi, Seung-Ho;Hwang, Jin-Ha;Lee, Deuck Hang;Kim, Kang Su;Kwon, Yong-Keun;Kim, Kil-Hee
    • Journal of the Korea Concrete Institute
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    • v.27 no.4
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    • pp.451-458
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    • 2015
  • The infill-wall strengthening method has been widely used for the seismic performance enhancement of the conventional reinforced concrete (RC) frame structures with non-seismic detail, which is one of the promising techniques to secure the high resisting capacity against lateral forces induced by earthquake. During the application of the infill-wall strengthening method, however, it often restricts the use of the structure. In addition, it is difficult to cast the connection part between the wall and the frame, and also difficult to ensure the shear resistance performances along the connection. In this study, an advanced strengthening method using the externally-anchored precast wall-panel (EPCW) was proposed to overcome the disadvantages of the conventional infill-wall strengthening method. The one-third scaled four RC frame specimens were fabricated, and the cyclic loading tests were conducted to verify the EPCW strengthening method. The test results showed that the strength, lateral stiffness, energy dissipation capacity of the RC frame structures strengthened by the proposed EPCW method were significantly improved compared to the control test specimen.

Axial Load Test of Prefabricated Composite Columns Using Bolt-connected Steel Angles (볼트접합 앵글을 사용한 합성기둥의 중심축 압축실험)

  • Kim, Hyeon Jin;Hwang, Hyeon Jong;Park, Hong Gun;Kim, Dong Kwan;Yang, Jong Min
    • Journal of Korean Society of Steel Construction
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    • v.29 no.2
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    • pp.147-158
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    • 2017
  • The present study focused on the structural performance of newly developed prefabricated composite columns (PSRC composite column) using bolt-connected steel angles. Concentric axial loading tests were performed for four 2/3 scaled PSRC column specimens and two conventional SRC column specimens. The test parameters were the spacing and sectional configurations of lateral reinforcement, and width-to-thickness ratio of steel angles. The test results showed that the axial load-carrying capacity and deformation capacity of the PSRC column specimens were comparable to those of the conventional SRC column specimens. Closely spaced steel plates and Z-shaped steel plates for lateral reinforcement increased the deformation capacity of the PSRC column specimens. The load-carrying capacity was greater than the prediction by current design codes. Numerical analysis was performed for the specimens. The results agreed well with the test results in terms of initial stiffness, load-carrying capacity, except for strength degradation due to cover concrete spalling.

Roles of Wind Stress Variations in the Western North Pacific on the Decadal Change of ENSO (ENSO 십년 변동에 미치는 북서태평양 지역에서의 바람 응력 변동의 역할)

  • Lee, Yoon-Kyoung;Moon, Byung-Kwon;Kwon, Min-Ho;Jhun, Jong-Ghap
    • Journal of the Korean earth science society
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    • v.27 no.6
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    • pp.687-694
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    • 2006
  • This paper investigated the effects of wind stress forcing in the western North Pacific on ENSO decadal change before and after the late 1970s. The SVD analysis of SODA data shows that a positive wind stress curl is dominant in the western North Pacific at the ENSO mature phase, which leads to the ENSO phase change by discharge/recharge heat contents in the equatorial Pacific. Before the late 1970s, the wind stress curl in the western North Pacific was strong. This strong wind forcing that is associated with the fast discharge of heat contents in the equator led to the short period and the weak intensity of ENSO occurred during the 1960-1970. On the other hand, after the late 1970s the relatively weak wind stress curl was accompanied with the long period and the strong intensity of ENSO. The simple coupled model experiments also confirm that the amplitude and dominant period of ENSO decrease when the wind stress curl in the western North Pacific projects more strongly into the ocean at the TNSO mature phase. Our results support that the changes in the behavior of ENSO after the late 1970s are associated with the wind stress variation in the western North Pacific.

Mechanical Properties and Microstructural Analysis of Sn-40Bi-X Alloys (Sn-40Bi-X 합금의 기계적 물성과 미세조직 분석)

  • Lee, Jong-Hyun;Kim, Ju-Hyung;Hyun, Chang-Yong
    • Proceedings of the KWS Conference
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    • 2010.05a
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    • pp.79-79
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    • 2010
  • 저온용 무연 솔더의 대표 조성으로 고려되고 있는 Sn-58Bi(융점: $138^{\circ}C$) 공정(eutectic) 조성은 우수한 강도에도 불구하고 연성(ductility) 측면에서의 문제점이 지속적으로 보고되고 있다. 따라서 이 합금계의 연성을 최대로 개선시킬 수 있으면서도 실제 상용화가 가능한 합금 조성의 개발 연구가 요청된다. 본 연구에서는 Sn-Bi 2원계 조성에서 최대의 연성을 나타내는 것으로 보고된 Sn-40Bi 조성에 미량의 합금원소를 첨가함으로써 최대의 연성을 확보하는 한편, 그 연성 특성이 변형속도에 어느 정도 민감한지를 인장 실험을 통해 결정하고자 하였다. 합금원소로는 0.1~0.5 wt%의 Ag, Mn, In, Cu를 선택하였으며, 인장 시편을 제조하여 $10^{-2}$, $10^{-3}$, $10^{-4}\;s^{-1}$의 3종류로 변형속도를 변형시켜가며 응력-변형 곡선(stress-strain curve)을 측정하였고, 조성별, 변형속도별로 최대인장강도(ultimate tensile stress, UTS) 및 연신율 결과들을 정리하였다. 합금원소를 첨가한 조성의 경우는 모든 시험 조건에서 Sn-40Bi보다 우수한 연신률을 나타내는 것으로 측정되었으나, $10^{-2}\;s^{-1}$의 빠른 변형속도에서는 그 향상 정도가 상대적으로 감소하는 경향이 관찰되었다. 특히 Sn-40Bi-0.5Ag 조성의 경우 느린 변형속도에서 특히 눈에 띄는 연신률 값을 나타내며, 모든 변형속도 조건에서 가장 우수한 연성을 나타내었다. 한편 Sn-40Bi-0.1Cu 조성의 경우 변형속도에 따른 연신률의 변화 정도, 즉, 변형속도에 따른 연신률의 민감도가 매우 커 $10^{-4}\;s^{-1}$ 속도에서는 Sn-40Bi-0.5Ag에 버금가는 연신률 값이 측정되었으나, $10^{-2}\;s^{-1}$ 속도에서는 가장 나쁜 연신률 특성을 보여주었다. Sn-40Bi-0.2Mn 조성은 최고의 연신률 향상 특성을 나타내지는 않았으나, In을 첨가한 경우보다는 대체적으로 우수한 연성을 나타내었다. 이상의 각 합금별 연성 특성은 인장시험 전의 미세조직 관찰 결과와 인장시험 후 파면부의 조직변화 관찰 결과로부터 해석되었다. 그 결과 석출상의 형성 여부, 인장 시험 중 재결정 조직의 형성 여부, 라멜라(lamellar) 조직의 분율과 라멜라 간격(lamellar spacing)의 정도 또는 $\beta$-Sn과 라멜라 조직 사이의 결정립계와 라멜라 조직 내 결정립계에서의 슬라이딩 모드(sliding mode) 변형 정도, 석출상의 크기와 분포 정도 등이 연신률 및 변형속도 민감도와 같은 연성 특성에 가장 큰 영향을 미치는 인자인 것으로 분석되었다.

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A Study on the Characteristics of High-Tension Bolted Joints' Behavior due to Surface Condition (표면상태에 따른 고장력볼트 마찰이음부의 거동특성에 관한 연구)

  • Cho, Sun Kyu;Hong, Sung Wook
    • Journal of Korean Society of Steel Construction
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    • v.9 no.3 s.32
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    • pp.421-430
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    • 1997
  • In this study, the static and the fatigue tests were performed with high tension bolted joints, of which the surfaces were spread with inorganic zinc-primer after shot-blast, and milling surface, and steel-natural surface, difference of friction surface condition were examined by comparing the esults of tests. From the result of synthetical investigation of this study. it is proper that using the torque management method in order to introduce design axial force to blots, and the provision of specifications that initial axial forces must be 110% of design axial forces is proper. Decreasing ratio of axial forces to initial force is proportional to common lorgarithms of time progress, it converge constant value after 20 hours, and decreasing ratio is little related to the roughness of friction surface. Sliding coefficient of milling, spreading inorganic zinc-primer, just producting is great in order and sliding forces are dependent on the applied axial forces, but if the applied axial forces are great, sliding coefficient become small by a loss of roughness. So it is confirmed that relation between the applied axial forces and the sliding forces are not proportional linearly. From the result of estimation on fatigue strength, all specimens satisfy the specifications with B-grade and milling surface is lower than the others about 14% in fatigue strength because in milling surface lose the function of friction-types joints at lower number of cycles. From the result of eximination for the distribution area of compressive force, friction area near to inside bolt is wider in the direction of stress than near to outside. It is guessed that this situation occurs because outside bolts firstly change from the friction connection to the bearing connection.

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Evaluation and Test Method Characterization for Mechanical and Electrical Properties in BGA Package (BGA 패키지의 기계적${\cdot}$전기적 특성 평가 및 평가법)

  • Koo Ja-Myeong;Kim Jong-Woong;Kim Dae-Gon;Yoon Jeong-Won;Lee Chang-Yong;Jung Seung-Boo
    • Journal of the Microelectronics and Packaging Society
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    • v.12 no.4 s.37
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    • pp.289-299
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    • 2005
  • The ball shear force was investigated in terms of test parameters, i.e. displacement rate and probe height, with an experimental and non-linear finite element analysis for evaluation of the solder joint integrity in area array packages. The increase in the displacement rate and the decrease in the probe height led to the increase in the shear force. Excessive probe height could cause some detrimental effects on the test results such as unexpected high standard deviation and probe sliding from the solder ball surface. The low shear height conditions were favorable for assessing the mechanical integrity of the solder joints. The mechanical and electrical properties of the Sn-37Pb/Cu and Sn-3.5Ag/Cu BGA solder joints were also investigated with the number of reflows. The total thickness of the intermetallic compound (IMC) layers, consisting of Cu6Sn5 and Cu3Sn, was increased as a function of cubic root of reflow time. The shear force was increased up to 3 or 4 reflows, and then was decreased with the number of reflows. The fracture occurred along the bulk solder, in irrespective of the number of reflows. The electrical resistivity was increased with increasing the number of reflows.

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