• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.83-87
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• 2002

Aerospace industries are widely using honeycomb sandwich structures that it has high specific strength and stiffness, chemical material resistance and fatigue resistance. But, in repairing process of damaged areas, one of the problems is that delamination can be occurred in the sound areas during and/or after the exposure to the elevated curing temperature in case that the repair process is repeated. Therefore, this study was conducted Flatwise tensile, Drum peel and Long beam flexural strength tests to evaluate the degree of degradation of mechanical properties of the honeycomb sandwich structures by affecting thermal aging. As the results, the decrease of mechanical strength was observed at the specific specimen which is exposed over 50hrs at $127^{\circ}C$.

• Journal of Welding and Joining
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• 제28권2호
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• pp.66-73
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• 2010

Conventional fracture test of resistance spot weld had been performed without consideration of paint baking process in automobile manufacturing line. This study was aim to investigate the effect of paint baking on fracture mode and load carrying capacity in fracture test for resistance spot welded 780TRIP steels. With paint baking cycle after resistance spot welds, peel tests and microhardness were conducted on the as-welded and baked samples. Resistance spot welds in AHSS (Advanced High Strength Steels) are prone to display partial interfacial fractures during fracture test or vehicle crash. Baking cycle increased the load-carrying capacity of the resistance spot welded samples and improved the fracture appearance from partial to full button fracture for the L-type peel tests. Specially, the differences in fracture appearance are apparent when the nugget size of spot welds is small enough to produce the partial interfacial fracture. The comparison of macrohardness and microstructure between as-welded and baked samples showed that there are no large difference in change the fracture mode. However, the results of the instrumented indentation test suggested that fusion zone and HAZ of baked sample have less tensile and yield strength and proves that the tempering effects are applied and enhanced the resistance to fracture on welds with application of baking cycle.

• 한국염색가공학회지
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• 제19권1호
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• pp.24-30
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• 2007

Heat storage/release system in textile is a useful tool to increase energy efficiency and enhance comfortable microclimate of clothing. Phase change materials(PCM) are used in regulating storage and release properties of thermal energy. To investigate the temperature regulating ability of fabrics with PCM microcapsule(PCMMc), Nylon fabrics were coated with PCMMc via wet processing and they were characterized by SEM, DSC and infrared thermal analyzer. Also, water moisture transpiration, water penetration resistance, peel strength and washing durability of the fabrics were assessed. The water vapor permeation and water penetration resistance decreased with increasing PCMMc content. In DSC analysis, it can be seen that the microencapsulated fabric showed both exothermic md endothermic phenomena at specific temperature. Peel strength was decreased with increasing PCMMc content.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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• pp.29-32
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• 2002

The mechanical joining process of a sheet metal pair has been developed in order to replace the resistance spot welding process in case that joining of mechanically unweldable materials and coated sheet metals with different thickness are needed. Form-joining or clinching, a kind of mechanical joining process, is defined as joining process of a sheet metal pair by geometric constraint imposed by plastic deformation of workpieces without any additive part. It has been reported that the joining strength by commercial form-joining apparatus is 50∼70 percent of that by resistance spot welding. Therefore, a two-step form-joining process with a secondary punch is proposed. The device is designed to improve the joining strength by increasing the geometric constraint of the deformed shape by combining a primary punch, a secondary punch and a female die. In order to verify the improved joining strength by the designed process, the tensile-shear strength, the peel-tension strength and the asymmetric peel-tension strength are compared with those by the TOX process and resistance spot welding.

• 한국재료학회지
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• 제17권10호
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• pp.509-515
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• 2007

In order to fabricate adhesiveless 2-layer flexible copper clad laminate (FCCL) used for COF (chip on film) with high peel strength, polyimide (PI; Kapton-EN, $38\;{\mu}m$) surface was modified by reactive $O_2^+$ and $N_2O^+$ ion beam irradiation. 300 mm-long linear electron-Hall drift ion source was used for ion irradiation with ion current density (J) higher than $0.5\;mA/cm^2$ and energy lower than 200 eV. By vacuum web coating process, PI surface was modified by linear ion source and then 10-20 nm thick Ni-Cr and 200 nm thick Cu film were in-situ sputtered as a tie layer and seed layer, respectively. Above this sputtered layer, another $8-9{\mu}m$ thick Cu layer was grown by electroplating and subsequently acid and base resistance and thermal stability were tested for examining the change of peel strength. Peel strength for the FCCLs treated by both $O_2^+$ and $N_2O^+$ ion irradiation showed similar magnitudes and increased as the thickness of tie layer increased. FCCL with Cu (200 nm)/Ni-Cr (20 nm)/PI structure irradiated with $N_2O^+$ at $1{\times}10^{16}/cm^2$ ion fluence was proved to have a strong peel strength of 0.73 kgf/cm for as-received and 0.34 kgf/cm after thermal test.

• Elastomers and Composites
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• 제43권1호
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• pp.39-48
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• 2008

상용 에폭시 수지의 접착력은 XNBR을 첨가함으로써 달성할 수 있으나 이는 필연적으로 유리전이온도(Tg)의 감소를 수반하여 접착제의 내열성을 저하시킨다. 1,3-bis(3-aminopropyl) tetramethyldisiloxane과 hydroxy phthalic anhydride를 반응시켜 siloxane-imide를 합성하고, 이를 상용 에폭시 수지와 공중합시켜 변성 에폭시 수지를 합성하였다. 변성 에폭시 수지의 siloxaneimide 함량을 결정하기 위하여 접착력 및 유리전이온도를 2관능성 에폭시 수지의 경우와 비교하여 조성비를 정하였다. Siloxane-imide와 공중합된 30% 변성 에폭시 수지는 5% XNBR을 첨가한 경우 0.42 N/mm의 박리 강도와 $155^{\circ}C$의 유리전이온도를 나타내어 die-bond용 접착제에 요구되는 물성 값인 0.3 N/mm 이상의 박리 강도와 $150^{\circ}C$ 이상의 유리전이온도를 충분히 만족 시킴을 알 수 있었다. 변성 에폭시 수지의 내 산성, 내 알칼리성 및 내습성을 평가한 결과 벤젠 링과 이미드 링의 영향으로 산, 염기 조건에서는 상용 에폭시 수지 대비 무게 변화폭이 감소하였지만 수분 조건에서는 무게 변화폭이 증가한 것을 알 수 있었다. 5% XNBR을 첨가한 30% 변성 에폭시 수지의 경우, 인장응력과 신장률이 상용 에폭시 수지 대비 약 220% 향상되었는데 이는 siloxane의 유연한 성질 때문인 것으로 판단된다.

• 한국재료학회지
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• 제9권12호
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• pp.1176-1180
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• 1999

Polyetherimide와 실리콘 사이의 RIE 처리 및 알루미늄 킬레이트 계열의 adhesion promoter 처리에 따른 접착력과 고온고습환경에서의 신뢰성 변화를 연구하였다. 실험 방법으로는 180$^{\circ}$ 필 테스트 및 <85$^{\circ}C$ 85%> 테스트, SEM, AFM, 증류수 접촉각 실험이 수행되었다. $^O_2$ RIE 실험 결과 초기 접착력은 RIE 처리시간에 따라 약간의 변화를 가져왔으나 고온고습 환경에서의 저항성은 급격히 떨어지는 것이 관찰되었고 이것은 표면 거칠기의 영향이 아닌 표면의 친수성 정도에 따른 것으로 나타났다. Al-chelate adhesion promoter의 경우 초기 접착력에는 변화가 없으나 고온 고습환경에서의 저항성이 크게 증가하였는데 이것은 표면이 소수성으로 변한 데 따른 것으로 나타났다.

• Korean Chemical Engineering Research
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• 제48권2호
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• pp.193-197
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• 2010

현재 포장 공정에서 사용되고 있는 stretch wrapping 공정은 초기 포장기의 장치 구비 등의 가격문제와 사용 후 폐기되는 포장재의 처리문제가 심각하다. 이에 대해 미끄럼 방지 접착제(Slip-resistant adhesive)를 사용하여 물류를 고정하여 운반하는 방식은 간단한 접착제의 도입으로 폐기물 발생이 없고 공정이 간단하며 비용이 매우 낮은 장점을 지닌다. 본 연구에서는 다습한 환경에서 polyethylene 필름 상에 미끄럼 방지 접착제를 적용했을 경우 접착력이 저하되는 것을 peel test를 통해 확인하고 적절한 첨가제의 선정 및 도입을 통해 접착력을 개선하는 연구를 수행하였다. 이를 통해서 maltodextrin의 첨가 시에 내습성에 대한 개선으로 인해 미끄럼 방지 접착력의 저하가 억제되었으며 10 wt% 도입 시에 최적의 성능을 나타내었다.

• Journal of Welding and Joining
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• 제21권5호
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• pp.513-517
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• 2003

Resistance welding processes are widely used in automotive applications. In particular, Mash-Seam resistance welding is typically used in Tailored Blank process. If spot welds are changed to a continuous weld, it's easy to reduce noise and to be more stable in cars. A arc welding, laser welding, seam welding using wheel electrode are available to make continuous welds on a car body, but they demand operator with advanced skills and expensive cost to develop. Therefore, flat electrode continuous mash-seam resistance welding process has been used to improve the weak points in currently available system in lap seam welding. This developed process has much more strength and air tightability, and also has much better plastic workability than laser welding. Moreover, commercial RSW machine can be readily used in this welding process.

• 접착 및 계면
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• 제1권1호
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• pp.15-22
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• 2000

4원 아크릴 점착제를 합성하기 위하여 butyl acrylate(이하 BA), 2-ethylhexylacrylate(이하 2-EHA), methylmethacrylate(이하 MMA), 2-hydroxyethylmethacrylate(이하 2-HEMA)를 사용하였다. 점착제 구조는 FT-IR, 분자량 분포는 GPC로 측정하고 점도, 고형분 그리고 점착력도 조사하였다. 단량체와 용제의 부피비가 1.3:1일 때 점착력이 $160g_f/25mm$이며 가장 범용성이 있었다. 열처리속도가 50 m/min이었을 때 가사시간이 30 s이었으며, 최소 경화시간은 30 s로 확인하였다. 내후성 시험에서 1000 h 경과 후에도 점착력이 $160{\sim}180g_f/25mm$로 거의 일정하게 유지되었고, 점착 잔유물은 없었다.