• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.171-176
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• 2003

In this study, stress analysis using Boundary Element Method (BEM) was carried to investigate stress distribution in the brazing joint between a Hardmetal and a HSS. The two models were proposed to analyze the stress singularity in the interfaces of the brazing joint. The material type, thickness of the filler metal and the length of the vertical brazing adhesive are considered in the BEM analysis. As results, the peak point of the stress is founded to be in the lower interface of the brazed joint. It should be noted that the maximum stress of the peak point is being affected by the thickness and length of the brazing joint.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.323-327
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• 1993

Mold-making industry demands currently to reduce the tooling costs and time in mold making, and to improve the productivity and quality in injection molding process. These problems can be easily removed by laminated injection mold which is made with metal sheets prepared by laser cutting and bonded by brazing. Comparing withthe conventional mold making technology which mainly depends on the machining, this new technologyenables an arbitary design of cooling circuit without anyrestrictions of geometry. So it brings about high production rates of the injection molding processes. This paper estimate the conventional and laminated injection mold making process with a simple molding, and also the cooling efficiencyof thoes two kinds of mold with the filling and cooling analysis. The results show that the laminated injectionmold has much shorter tooling time, uniform mold temperature, and shorter cooling time in injection molding process.

• Journal of Powder Materials
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• v.4 no.4
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• pp.252-257
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• 1997

Cu-brazed layer between the sintered-cam(Fe-5Cr-lMo-0.5P-2.5C, wt%) and seamless steelpipe(0.25-0.35C, 0.3-1.0 Mn, bal Fe, wt%) in the camshaft shows a columnar structure of $\gamma$-phase growing from the steel pipe. Liquid phase sintered 60Fe-40Cu alloys are carburized to simulate the brazing process giving rise to the columnar growth. Liquid film migrations and columnar growth of $\gamma$-grains are observed in the carburized regions. The $\gamma$-grains grow in the same direction as the C-diffusion. Fe-solubility in the liquid of carburized region is higher than in the uncarburized by about 0.3 at%. The columnar growth is driven by the gradient of the supersaturated Fe-solute in the liquid between two adjacent $\gamma$-grains.

• Journal of Welding and Joining
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• v.11 no.2
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• pp.1-12
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• 1993

용접과 관련되는 분야에서, 재료평가와 비파괴 검사법으로서의 Acoustic Emission의 응용을 살펴 보았다. 재료 평가법으로서의 AE는 다른 시험방법들이 검출해 내지 못하는 재료 내부에서의 미시적인 현상들을 정량적으로 평가할 수 있는 장점을 가지고 있다. 앞으로 새로운 용접재료의 개발이라든지, 고도의 신뢰성이 요구되는 용접부위의 정량적인 평가를 위해서 AE의 응용은 중요한 정보들을 제공하게 될 것이다. 한편 용접구조물의 비파괴적 평가법으로서의 AE는 균열의 동적인 거동 및 균열의 위치를 검지할 수 있다는 장점 때문에 응용범위는 더욱 넓어질 것이다. 여기서 유의하여야 할 점은, 목적으로 하는 AE신호를 수만배 까지 증폭시키는 과정에서 환경잡음의 영향을 무시할 수 없는 경우에는 우선적으로 잡음을 적극적으로 제거하는 고도의 연구도 함께 병행되어야 한다는 것이다.

• Journal of Welding and Joining
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• v.21 no.2
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• pp.64-69
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• 2003

The bonding phenomena and mechanical property of duplex stainless steel during brazing have been investigated. The UNS32550 was used for base metal, and the MBF50 was used for insert metal. Brazing was carried out under the various conditions (brazing temperature : 1473K, 1498K, holding time : 0∼1.8ks). There were various microconstituents in the bonded interlayer because of reaction between liquid insert metal and base metal. In the early stage of brazing, BN is formed in the bonded interlayer and base metal near the bonded layer. Cr made is formed in the bonded interlayer. The amount of BN and Cr nitrides decrease with the increase of bonding temperature and holding time. Superior shear strength of 550MPa is obtained by restraining the formation of nitrides. (Received January 17, 2003)

• Journal of Welding and Joining
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• v.19 no.5
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• pp.534-539
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• 2001

The formation mechanism of microconstituents in brazed joints of duplex stainless steel and Cr-Cu alloy which is an essential process of rocket engine manufacturing was investigated using Cu base insert metal. $SUS329J_3L$ and C18200 were used for base metal and AMS 4764 was used for insert metal. The brazing was carried out under various conditions. There were various phases in the joints, because of reaction between liquid insert metal and base metals. Since liquid insert metal reacts with duplex stainless steel, liquid Cu from insert metal infiltrated into the $\alpha/\beta$ interface of duplex stainless steel. Through the process of Cu infiltration, isolated stainless steel pieces come into the liquid insert metal. Since liquid insert metal reacts with Cr-Cu alloy. Cr precipitates from C18200 come into the liquid insert metal. With increment of bonding temperature and holding time, amounts and sizes of phases increased. but Cr-Mn compounds decreased at 1303k for 1.2ks and Mn-rich phases disappeared Fe-Cr compounds formed.

• Journal of the Korean Society for Heat Treatment
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• v.20 no.4
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• pp.203-208
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• 2007

고출력 다이오드레이저(High Power Diode Laser, HPDL)는 독일을 중심으로 한 유럽내의 여러 국가에서 적용분야를 점차 높여가고 있으며, 금속소재에 있어서의 높은 흡수율 및 발진장치의 높은 에너지 변환효율이 중요한 요인이라고 할 수 있다. 레이저소스로부터 출력되는 사각형 또는 라인형의 레이저-빔은 다이오드레이저를 이용한 금속의 열처리분야에 매우 적합하며, 이미 Body-in-White 차체(Car Body) 양산라인의 브레이징 공정에는 수 년 전부터 실제 적용되어왔다. 또한, 다양한 빔 형상, 균일한 에너지 밀도, 낮은 운전비용, 간단한 유지보수, 좁은 설치공간, 손쉽게 이동이 가능한 구조, 광케이블을 이용한 레이저-빔의 전송 등 여러 장점으로 인하여 보다 유연하고 효과적인 생산환경을 구축할 수 있다는 것 또한 다이오드레이저의 응용분야를 확대하는 요인이 되었다.

• Proceedings of the KWS Conference
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• 2004.05a
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• pp.45-47
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• 2004

We have investigated the microstructures and the mechanical properties of TiA1/Cerameti1721 (Ag-Cu-Ti insert metal)/AISI4140 joints at 800$^{\circ}C$ for 60 to 300s using induction brazing method. Two continuous reaction layers of AICuTi and AICu$_2$Ti were formed at the interface between the braze and TiAl, whose thickness increased with the brazing time. The braze consisted of Ag-rich, Ti-rich, CuTi and CuTi$_2$ phases. The maximum tensile strength achieved 296MPa, which was 71% of that of TiAl base metal, for the specimen bonded at 800$^{\circ}C$. Further increase of the brazing temperature and time resulted in constant deterioration of its bonding strength due to large amount of brittle IMC.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1729-1730
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• 2008

In the industry, the automation of brazing system is very important using the vision senor and the edge detection of the bronze pipe. And also, the accurate coordination is needed for the finding of the precise location. In this paper, we propose an algorithm for the measurement of 3D information of the brazing material and the detection algorithm of soldering area using the camera and IR sensor. We use Canny edge detector in noisy environments. The experimental study shows that camera and IR sensor is useful for the measurement of distance in the brazing work.

• Transactions of Materials Processing
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• v.21 no.8
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• pp.506-511
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• 2012

Aluminum brazing normally requires a careful control of temperature due to the small interval between brazing and melting temperatures for base materials. Unsuitable processing conditions, including brazing temperature outside admissible range, gap between brazed materials or inadequate flux feeding, can lead to joining defects. In this study, A357 was used as a filler metal for the brazing of pure aluminum base materials and brazed at temperatures in the semi-solid state. Interface microstructures with base materials were observed using optical metallography(OM) and scanning electron microcopy(SEM) with energy dispersive spectroscopy(EDS), and compared to conventional aluminum brazing.