• 마이크로전자및패키징학회지
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• 제23권4호
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• pp.93-99
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• 2016

본 논문에서는 AgNW 필름의 기계적 전기적 신뢰성을 연구하였다. 특히 전류가 흐르는 상태에서 굽힘 변형이 발생하였을 때의 AgNW 필름의 내구성 및 신뢰성을 연구하였다. AgNW 필름의 전압 및 전류 시험을 수행하여, AgNW에서 발생하는 발열과 전류 밀도의 변화를 관찰함으로써 AgNW의 전기적 내구성을 평가하였다. AgNW는 곡률반경 2 mm까지 굽힐 수 있었으며, 200,000회의 굽힘 반복시험에도 높은 신뢰성 및 유연성을 보여주었다. 또한 over-coating 막은 AgNW 필름의 내구성을 향상시키는 효과가 있음을 확인하였다. Over-coating이 없는 AgNW 필름의 경우, AgNW 표면에서 국부적인 발열을 보인 반면에 over-coating이 된 AgNW 필름의 경우 균일하게 발열되어 over-coating막이 AgNW 필름의 내구성을 향상시킴을 알 수 있었다. 전류를 인가한 상태에서의 굽힘 시험을 수행한 결과 굽힘 반복시험에서는 전류밀도가 지속적으로 감소하여 시험 후, 52.4%의 전류밀도 감소를 보였다. 전류가 인가된 상태에서 AgNW의 굽힘 변형이 지속되면 AgNW들의 인장, 굽힘 및 sliding 등의 기계적인 변형에 의하여 AgNW network 구조의 변형이 발생하거나, 혹은 개별 AgNW의 접촉 접합부들이 떨어지면서 접촉저항이 증가하여 주울 열에 의하여 파괴가 발생한다. 또한 over-coating막의 적용은 AgNW 필름의 전기적 신뢰성을 향상시킬 수 있음을 알 수 있었다.

• Journal of Electrochemical Science and Technology
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• 제12권2호
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• pp.225-229
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• 2021

Commercially available continuous glucose sensors require the operation stability for more than two weeks. Typically, the sensor comprises a sensing layer and an over-coating layer for the stable operation inside the body. In the sensing layer, enzymes and mediators are cross-linked together for the effective sensing of the glucose. The over-coating layer limits the flux of glucose and works as a biocompatible layer to the body fluids. Here, we report the simple preparation of the flux-limiting layer by the condensation of polyethyleneimine (PEI), tri-epoxide linker, and trimethylolpropane triglycidyl ether (PTGE). The sensor is constructed by a layer-by-layer drop-coating of the sensing layer containing glucose dehydrogenase and the PEI-derived blocking layer. It is stable for more than 14 days, which is enough for the sensor in the continuous monitor glucose monitoring (CGM) system.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 제5회 압연심포지엄 신 시장 개척을 위한 압연기술
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• pp.249-257
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• 2004

Drying and curing characteristics of PCM resins using the induction heater and short-wave infrared emitter module was studied to develop a compact oven system for the high speed CCL and post-treatment equipment. Drying of the polyester resins using the induction heater and infrared heater showed that the blistering tendency of polyester resin coating increased regardless of additives and colors of resins as the heating rate and/or dry film thickness increased. The blistering of polyester resin coating layer occurred when the heating speed was over than $25^{\circ}C/sec$ for the dry film thickness of $19\~20um$, which is the typical thickness of finish coating in CCL. So did it when the heating speed was over than $40^{\circ}C/sec$ for the dry film thickness over than 10 um. The heating efficiency of paint coated steels by the infrared heating was strongly dependent on the colors of paint coating and generally increased for the dark surface and/or coating. But the faster drying of the PCM resin coatings increased the blistering tendency of coating layer. The blistering limit for the typical finish coating by the infrared heating was estimated as the heating rate slower than $20^{\circ}C/sec$ regardless of colors of PCM resins.

• 한국정밀공학회지
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• 제12권11호
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• pp.52-62
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• 1995

In the laser surface hardening process the geometrical parameters, especially the depth, of the hardened layer are utilized to assess the integrity of the hardening layer quality. Monitoring of this geometrical parameter ofr on-line process control as well as for on-line quality evaluation, however, is an extremely difficult problem because the hardening layer is formed beneath a material surface. Moreover, the uncertainties in monitoring the depth can be raised by the inevitable use of a surface coating to enhance the processing efficiency and the insufficient knowledge on the effects of coating materials and its thicknesses. The paper describes the extimation results using neural network to estimate the hardening layer depth from measured surface temperanture and process variables (laser beam power and feeding velocity) under various situations. To evaluate the effec- tiveness of the measured temperature in estimating the harding layer depth, estimation was performed with or without temperature informations. Also to investigate the effects of coating thickness variations in the real industry situations, in which the coating thickness cannot be controlled uniform with good precision, estimation was done over only uniformly coated specimen or various thickness-coated specimens. A series of hardening experiments were performed to find the relationships between the hardening layer depth, temperature and process variables. The estimation results show the temperature informations greatly improve the estimation accuracy over various thickness-coated specimens.

• 수산해양교육연구
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• 제10권1호
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• pp.69-78
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• 1998

Thermal sprayed Cu-Ni alloy coating on the carbon steel was carried out impingement erosion-corrosion test and electrochemical corrosion test in the marine environment. The impingement erosion-corrosion behavior and electrochemical corrosion characteristics of substrate(SS400) and thermal sprayed Cu-Ni coating was investigated, and the corrosion control efficiency of Cu-Ni coating to substrate was estimated quantitatively. Main results obtained are as follows : 1) The weight loss rate of Cu-Ni coating layer by the impingement erosion-corrosion compared with substrate was smaller in high specific resistance solution than in low specific resistance solution. 2) The corrosion potential of Cu-Ni coating layer spray coating in the marine environment became more noble than that of substrate. 3) With the lapse of time, corrosion current density of Cu-Ni coating layer became stable, but that of substrate was increased. 4) As the corrosion control efficiency of Cu-Ni coating layer in the marine environment was over 90%, its anti-corrosion characteristics was excellent.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.113-116
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• 2005

In this paper, a computational and experimental analysis about the flow behavior of thin polymer film in the spin coating process for stable cover layer coating of a blu-ray disc is described. The blu-ray disc, a next-generation optical disc format over 25GB, consists of a 1.1mm thick substrate and a 0.1mm tick cover layer. Generally, cover layer on the blu-ray disc is made by the polymer spin coating process. However, it is hard to secure sufficient coating uniformity around the rim on the cover layer. In order to get the uniform thickness deviation and to minimize the bead around the rim, the edge of the disc substrate can be modified into various shapes around the rim on the disc and analyzed with various parameters, such as surface tension, viscosity, and rotation speed, etc. The optimal shape of the rim was tried to get by 3 dimensional computer simulation of the polymer expulsion process.

• Journal of Pharmaceutical Investigation
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• 제37권1호
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• pp.7-13
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• 2007

To produce stable polymer coating layer using the interaction between metal stent and polymer layer, Ahx-HSAB was synthesized by coupling 6-aminoheanoic acid (Ahx) with N-Hydroxy succinimidyl 4-azidobenzonate (HSAB) containing photo reactive group. Then, Ahx-HSAB was applied to self·assembled monolayer (SAM) on $TiO_2$-coated surface, since one end of Ahx-HSAB was carboxyl acid which was known to be able to interact with $TiO_2$ surface. That SAM layer was incubated in 1% polycaprolacton (PCL) solution and photoreacted by ultraviolet light (254 nm) to produce the chemical bond between SAM and polymer layer, followed by PCL polymer coating ({\sim}5\;{\mu}m$) by the method of spray coating. The surface change was investigated by measuring of contact angle of the surface. The contact angle values of stainless steel (SS) surface, $TiO_2$-coated surface, SAM layer by Ahx-HSAB, photoreacted surface with PCL and PCL layer by spray coating were 70.48${\pm}$1.89, 38.57${\pm}$3.31, 60.14${\pm}$2.21, 54.91${\pm}$2.70 and 56.47${\pm}$2.12, respectively. The stability of polymer layers was tested by incubation of PCL-coated plates in 0.1M PBS buffer (pH 7.4, 0.05%, Tween 80) with vigorous shaking (200 rpm). While the poiymer layer prepared by these processes showed the intact surface morphology over 3 days, the polymer layers prepared by spray coating of PCL onto SS plate (control 1) and $TiO_2$-coated SS plate (control 2) were Peeled off in 3 days. Thus, the polymer coating method using SAM and photoreaction seems to be a effective method to obtain the stable polymer layer onto SS surface.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.467-471
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• 2005

In this paper, experimental methods about the flow behavior of thin polymer film by various edge patterns in the spin coating process for stable cover layer coating of a blu-ray disc is described. The blu-ray disc, a next-generation optical disc format over 25GB, consists of a 1.1m thick substrate and a 0.1mm tick cover layer. Generally, cover layer on the blu-ray disc is made by the polymer spin coating process. However, it is hard to secure sufficient coating uniformity around the rim on the cover layer. In order to get the uniform thickness deviation and to minimize the bead around the rim, the edge of the disc substrate can be modified into various patterns, such as normal plain, trench, step and chamfer pattern, etc, around the rim on the disc and experimented with various parameters, such as surface tension, viscosity, coating time, temperature and rotation speed, etc. And the optimal shape of the rim was tried to get by 3 dimensional computer simulation of the polymer expulsion process.

• Corrosion Science and Technology
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• 제11권1호
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• pp.29-36
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• 2012

The resistance spot welding of high strength steel degrades the weldability because of its high strength with rich chemical composition and coating layer to protect from corrosion. During the each resistance welding process the electrodes tip reacts with coating layer, then subsequently deteriorates and shorten electrode life. In this study, the Al-coated HPF (Hot Press Forming) steels and Zn-coated TRIP steels were used to investigate the electrode life for resistance spot welding. Experimental results show that the reactivity of Al-coating on HPF steels to electrode tip surface behaviors different from the conventional Zn-coated high strength steels. The electrode tip diameter and nugget size in electrode life test of Al-coated HPF steels are observed to be constant with respect to weld numbers. For Al-coated HPF steels, the hard aluminum oxide layer being formed during high temperature heat treatment process reduces reactivity with copper electrode during the resistance welding process. Eventually, the electrode life in resistance spot welding of Al-coated HPF steels has the advantage over the galvanized steel sheets.

• 한국재료학회지
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• 제11권6호
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• pp.441-447
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• 2001

PACVD 방법으로 다이캐스팅용 금형에 적용할 수 있는 TiN 코팅막을 형성시키는 연구를 하였다. 직류 펄스전원을 사용하여 지름이 4 mm인 작은 동공내부에 최고 20 mm 깊이까지 균일한 TiN 코팅층을 형성할 수 있었다. 코팅공정시 발광분광분석기를 사용해 Ti와 $N_{2}$ 및 $Ar^{+}$의 분광선을 측정함으로써 TiN 코팅막의 형성기구에 대하여 고찰하였다. 듀티비율이 50% 이상인 경우는 Ti, $N_{2}^{+}$ 및 $Ar^{+ }$ 의 분광선이 나타났으나, 듀터비율이 28.6%이하인 경우 분광선이 전혀 나타나지 않았으며 TiN 코팅층의 형성도 불안정하였다. 펄스전원으로 Bipolar로 사용한 경우 Unipolar를 사용한 경우보다 지름이 4 mm인 구멍에서 2배 깊게 코팅되었다.