• Journal of Advanced Marine Engineering and Technology
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• 제19권3호
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• pp.50-61
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• 1995

In recent years, many ceramic researchers have discoved various methods of joining ceramic to metal. However, most of these joining methods are perfomed under vacuum and pressured circumstances. So, when we join ceramic to metal,the proceedings are very complicated and require a very high cost. The purpose of this study is to develop a new joining method of an alumina ceramic to an aluminum metal in air atmosphere. The joining condition, such as copper metallizing, nickel plating, brazing, etc. was investigated through the shear strength test of the trial joint. The results obtained from the above experimenta are summarized as follows : 1) In the case of the $Al_2O_3$/$Al_2O_3$joint, the shear strength of the joint was affected by the various foctor such as kaolin content, copper metallizing thickness, firing temperature, firing time. 2) The better shear strength of the $Al_2O_3$/Al joint was obtained when Ni plating was conducted under higher current density than existing plating condition. 3) The shear strength of the $Al_2O_3$/Al joint increases with the Ni plating thickness is confined to the range of this paper. 4) The shear strength of the thermal-shocked specimen($Al_2O_3$/Al joint) was far more deteriorated than that of the as-bonded specimen.

• Journal of Welding and Joining
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• 제34권5호
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• pp.70-76
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• 2016

In this study, Microstructure and tensile properties in arc brazed joints of 1000MPa grade DP steel using Cu-Si insert metal were investigated. The fusion zone was composed of Cu phase which solidified a little Fe and Si. The former phase formed due to dilute the edge of base material by arc, although Fe was not solid solution in Cu at the room temperature. Cu3Si particles formed by crystallization at $1100^{\circ}C$ during faster cooling. After the tensile shear test, there are no differences between the brazed joint efficiencies. The maximum joint efficient was about 37% compared to strength of base metal. It is better than that of arc brazed joint of DP steel using Cu-Sn filler metal. Fracture position of all brazing conditions was in the fusion zone. Crack initiation occurred at three junction point which was a stress singularity point of upper sheet, lower sheet and the fusion zone. And then crack propagated across the fusion zone. The reason why the fracture occurred at fusion zone was that the hardness of fusion zone was lower than that of base material and heat affected zone. The correlation among maximum load and hardness of fusion zone and EST at fractured position was $R^2=0.9338$. Therefore, this means that hardness and EST can have great impact on maximum load.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2007년도 추계학술 발표회
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• pp.193-198
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• 2007

KIER has been developing the anode supported flat tubular SOFC stack for the intermediate temperature $(700{\sim}800^{\circ}C)$ operation. for this purpose, we have first fabricated anode supported flat tubular cells by the optimization between the current collecting method and the induction brazing process. After that we designed the compact fuel & air manifold by adopting the simulation technique to uniformly supply fuel & air gas and the unique seal & insulation method to make the more compact stack. For making stack, the prepared anode-supported flat tubular cells with effective electrode area of $90cm^2$ of connected in series with 12 modules, in which one module consists of two cells connected in parallel. The performance of stack in 3 % humidified $H_2$ and air at $800^{\circ}C$ shows maximum power of 507 W. Through these experiments, we obtained basic & advanced technology of the anode-supported flat tubular cell and established the proprietary concept of the anode-supported flat tubular SOFC stack in KIER.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.268-271
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• 2007

A sandwich tube is a structured material that has two inner and outer circular tubes and light material between them. In this paper, a sandwich tube with a pyramidal truss core is introduced. Fabrication method and example made by brazing are shown. The behavior of the sandwich tube under lateral loading is predicted by analytical and numerical method. Comparative study between the sandwich and the monocoque tube is performed at a point of view such as strength and weight saving. As a result, proposed tube is appropriate for application to lightweight structural material

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.342-348
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• 2002

The welding technology for production of power plant facility as for other industries has been progressing forward automation and mechanization for cost reduction and shortening of cycle time. The welding for boiler tube is automated or mechanized as the parts and subassemblies of tubes are conveyed automatically in the shop. The temperature of boiler stearn is being progressively increased for higher plant efficiency. The welding of nuclear component is characterized by heavy thickness and narrow gap Submerged Arc Welding. Narrow gap Gas Metal Arc Welding and Electron Beam Welding is applied to turbine diaphragm. To improve the resistance of solid particle erosion of turbine blade and nozzle partition, HVOF spray technology and boriding process has been applied.

• 한국생산제조학회지
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• 제21권6호
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• pp.926-931
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• 2012

Rotary bar was cutting tool being in use for deburring scale after welding metal and for eliminating sharp edges. It was necessary to develop exclusive 6-axis machine being possible to process machining continuously for making an cutting edge of rotary bar and to revise easily machining program. This study aimed at the structural analysis of strength according to the configuration of new made 6-axis machine and at the machining accuracy and durability of rotary bar. As a result of test, the runout of new rotary bar manufactured out of 6-axis machine was decreased from 0.385 mm to 0.027mm extensively than old one. And good cutting ability and durability was obtained equal quality compared with imported products.

• 마이크로전자및패키징학회지
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• 제26권3호
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• pp.15-22
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• 2019

In these days, importance of the power electronic devices and modules keeps increasing due to electric vehicles and energy saving requirements. However, current silicon-based power devices showed several limitations. Therefore, wide band gap (WBG) semiconductors such as SiC, GaN, and $Ga_2O_3$ have been developed to replace the silicon power devices. WBG devices show superior performances in terms of device operation in harsh environments such as higher temperatures, voltages and switching speed than silicon-based technology. In power devices, the reliability of the devices and module package is the critically important to guarantee the normal operation and lifetime of the devices. In this paper, we reviewed the recent trends of the power devices based on WBG semiconductors as well as expected future technology. We also presented an overview of the recent package module and fabrication technologies such as direct bonded copper and active metal brazing technology. In addition, the recent heat management technologies of the power modules, which should be improved due to the increased power density in high temperature environments, are described.

• 한국재료학회지
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• 제17권6호
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• pp.342-346
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• 2007

Microstructure and tensile strength of the vacuum brazed stainless steel were investigated in this study. For vacuum brazing of the stainless steel 303 and 304, the BNi-2, 3, 4 and 7 were used as filler metals. Among these filler metals, the BNi-2 showed excellent wettability at $1050^{\circ}C$. Indeed, the brazed stainless steel using the BNi-2 showed the highest tensile strength (483 MPa) among all brazed specimens. This is attributed to degree of interfacial reaction between the filler metal and stainless steel. Brazed stainless steel with BNi-2, 3 filler metals showed almost elastic deformation followed by plastic yielding and strain hardening up to a peak stress. On the other hand, it is likely that the fracture of the brazed specimens with BNi-4, 7 was occurred in elastic range without plastic yielding up to a peak stress.

• Journal of Welding and Joining
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• 제29권4호
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• pp.54-60
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• 2011

Adhesive bonding is one of the most promising joining methods which may substitute for conventional metallurgical joining processes, such as welding, brazing and soldering. Curing behavior and mechanical properties of adhesive joint are largely dependent on the curing agent including hardener and catalyst. In this study, effects of curing system on the curing behavior and single-lap shear strength of epoxy adhesive joint are investigated. Dihydrazide, anhydride and dicyandiamide(DICY) were chosen as hardener and imidazole and triphenylphosphine(TPP) were chosen as catalyst. In curing behavior, TPP showed the delay of the curing rate for DICY and ADH at $160^{\circ}C$, compared to imidazole catalyst due to the high curing onset/peak temperature. DICY seemed to be most beneficial in the joint strength for both steel and Al adherends, although the type of adherends affected the shear strength of epoxy adhesive joint.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1976-1978
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• 2002

micro CPL 제작을 위한 LICA 및 MEMS 공정을 개발하였으며 양산화를 위한 새로운 방법으로 ${\mu}$MIM(micro Metal Injection Molding) 기술을 제안하였다. 먼저 LIGA 기술을 이용하여 Cu 도금 구조물로 이루어진 micro CPL 구조물을 제작하였다. 각각 상판과 하판 구조물로 나누어 제작하였으며 상, 하판 Cu 구조물을 brazing 방법을 이용하여 접합하였다. 또한 micro CPL 내부에서 일어나는 냉매의 흐름 및 상변화(liquid ${\leftrightarrow}$ vapor) 거동을 관찰할 수 있는 새로운 개념의 Si/glass 투명 micro CPL을 제작하였다. 상기 공정을 이용하여 냉각 능력이 10w/$cm^2$ 이상인 micro CPL을 제작하였다. 상기 연구 결과를 바탕으로 양산화를 위한 새로운 정밀복제기술인 ${\mu}$MIM(Micro Metal Injection Molding) 공정을 개발하였다. LISA 공정으로 제작된 정밀 금형을 core금형으로 사용하였고 $1{\mu}m$ 이하의 W-Cu(10%) powder와 binder가 혼합된 흔합분말을 이용하여 micro channel 구조물(선폭 $100{\mu}m$)의 성형 복제에 성공함으로서 양산화를 향한 기반기술을 확립하였다.