• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.778-781
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• 2002

Durability of rubber dust cover in the ball joint for automotive suspension parts were analyzed by FEM and compared with experimental data. Upper open area of ball joint is sealed by dust cover for preventing outflow of the lubricating oil and intrusion of send, dust, water, etc. This rubber cover undergoes repeated loadings such as tension and compression while the car is running. Analysis about rubber material needs to consider every kinds of nonlinearities arise in finite element analysis, which are geometric nonlinearity due to large displacement and small strain, materially nonlinearity and nonlinear boundary condition such as contact. So in the study, the deformation behavior of dust cover was analysed by using the commercial finite element program MARC. This program could solve these kinds of nonlinear analysis accurately. Finite element model of dust cover is considered as 3-dimensional half model based on 2-dimensional axisymmetric model. Material property of rubber was modeled by Ogden model and input data for calculation takes form uniaxial tension test of rubber specimen, The final object of the study is obtaining the design specification of dust covers and the result of analysis should be a useful data to design of rubber

• 한국재료학회지
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• 제9권1호
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• pp.65-72
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• 1999

In order to minimize flexible printed circuit(FPC), which is used in computer, communication, medical facility, aviation space industry, it is required to improve the interfacial adhesion of polymide/epoxy or polyimide/polyimide consists of FPC. In this study, it was considered to improve the adhesion strength of polyimide/epoxy joint by introducing functional group on polyimide film and improving mechanical property of epoxy. Functional group on polyimide film was introduced by changing polyimide film surface to polyamic acid in KOH aqueous solution. The optimum conditions for surface modification were the concentration of 1M KOH and treatment time of 5min. Also, the optimum adhesion strength of polyimide/epoxy joint was obtained using rubber modified epoxy and polyamic acid as a base resin and curing agent of epoxy adhesive, respectively. The degree of surface modification of polyimide film examined with contact angle measurement of FTIR, thus modification of polyimide to polyamic acid was identified. Fracture surface of plymide/epoxy joint was analyzed by scanning electron microscopy, and modified polyamic acid reimidezed to polymide as increasing curing temperature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.93-93
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• 2010

We developed friction welded bimetallic sleeve for 220kV aluminum conductor XLPE cable. Not only friction welded bimetallic sleeve for Termination(EB-A, EB-G) but also friction welded sleeve for Joint of Al to Cu conductor was developed regardless of this project. Generally, friction welded sleeve used to connect Al conductor cable to Cu conductor cable and used for improvement of mechanical property of terminal by offer the copper side of friction welded bimetallic sleeve at the Termination. Connection method for Al-Cu conductor has mainly used friction welding at the solid state, because it is difficult to connect by using conventional welding method. this investigation introduces development of friction welded bimetallic sleeve by friction welding and test result of 220kV Al conductor XLPE cable and accessories using friction welded sleeve.

• 한국음향학회지
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• 제21권5호
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• pp.438-445
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• 2002

본 논문에서는 격자 트랜스버설 결합 (LTJ) 적응필터를 시변 변환영역 적응필터 관점에서 해석함으로써 필터계수보상의 필요성을 보다 쉽고 일반적으로 해석하였다. 또한, 음성 신호가 단구간에서 정적이라는 특성을 이용하여 필터계수 보상을 위한 계산량을 감소시킬 수 있는 방법을 제안하였으며, 모의 음성신호와 실제 음성신호를 사용한 실험을 통하여 효용성을 입증하였다. 제안된 적응필터는 필터계수 보상을 위한 계산량이 95% 감소되었으며, 1000탭을 사용하는 음향반향제거기의 경우 전체 시스템의 계산량을 82% 감소시킬 수 있다.

• 한국CDE학회논문집
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• 제10권5호
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• pp.375-379
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• 2005

Durability of rubber dust cover in the ball joint for automotive suspension parts is analyzed by FEM and compared with experimental data. Upper open area of ball joint is sealed by dust cover for preventing outflow of the lubricating oil and intrusion of send, dust, water, etc. This rubber cover undergoes repeated loadings such as tension and compression while the car is running. Analysis about rubber material needs to consider every kinds of nonlinearities arise in finite element analysis, which are geometric nonlinearity due to large displacement and small strain, materially nonlinearity and nonlinear boundary condition such as contact. The deformation behavior of dust cover is analysed by using the commercial finite element program MARC. In the study, this program could solve these kinds of nonlinear analysis accurately. Finite element model of dust cover is considered as 3-dimensional half model based on 2-dimensional axisymmetric model. Material property of rubber is modeled by Ogden model and input data for calculation takes form uniaxial tension test of rubber specimen. The final object of the study is obtaining the design specification of dust covers and the result of analysis should be a useful data to design of rubber cover.

• 열처리공학회지
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• 제34권6호
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• pp.309-314
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• 2021

Due to the superior corrosion resistance and mechanical properties of TiAl alloy at high temperature, it has been utilized as a turbine wheel of a turbocharger. The dissimilar metallic bonding is usually applied to combine the TiAl turbine wheel with the SCM440 structural steel which is used as a driving shaft. In this study, the TiAl and SCM440 joint were fabricated by using a friction welding technique. During bonding process, to suppress the martensitic transformation and the formation of cracks, which might reduce a strength of the joints, Cu was used as an insert metal to relieve stress. As a result, the intermetallic compounds (IMCs) layer was observed at TiAl/Cu interface while no IMC formation was formed at SCM440/Cu interface. Since understanding of the IMCs effects on the mechanical performance of welded joint is also essential for ensuring the reliability and integrity of the turbocharger system, we estimated the nanohardness of welded joint region through nanoindentation. The relation between the microstructural feature and its mechanical property is discussed in detail.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.539-544
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• 2002

Titanium and titanium alloy are excellent in corrosion resistance and specific intensity, and also in the biocompatibility. On the other hand, the brazing is bonding method of which productivity and reliability are high, when the complicated and precise structure of the thin plate is constructed. However, though conventional titanium-based brazing filler metal was excellent in bond strength and corrosion resistance, it was disadvantageous that metal structure and mechanical property of the base metal deteriorated, since the brazing temperature (about 1000 C) is considerably high. Authors developed new brazing filler metal which added Zr to Ti-Cu (-Ni) alloy which can be brazed at 900 C or less about 15 years ago. In this paper, the development of more low-melting-point brazing filler metal was tried by the addition of the fourth elements such as Ni, Co, Cr for the Ti-Zr-Cu alloy. As a method for finding the low-melting-point composition, eutectic composition exploration method was used in order to reduce the experiment point. As the result, several kinds of new brazing filler metal such as 37.5Ti-37.5-Zr-25Cu alloy (melting point 825 C) and 30Ti-43Zr-25Cu-2Cr alloy (melting point: 825 C) was developed. Then, the brazing joint showed the characteristics which were almost equal to the base metal from the result of obtaining metallic structure and strength of joint of brazing joint. However, the brazing filler metal composition of the melting point of 820 C or less could not be found. Consequentially, it was clarified that the brazing filler metal developed in this study could be practically sufficiently used from results such as metal structure of brazing joint and tensile test of the joint.

• 마이크로전자및패키징학회지
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• 제21권3호
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• pp.51-56
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• 2014

솔더조인트의 신뢰성에는 인쇄회로기판의 표면처리 특성이 많은 영향을 미치고 있다. 본 연구에서는 ENEPIG 표면처리에서 Sn-4.0wt%Ag-0.5wt%Cu (SAC405) 솔더와 Pd 촉매 처리 시간에 따른 high speed shear 에너지 및 파괴 모드를 연구하였다. 또한 Pd 촉매 처리 시간과 무전해 Ni-P 도금의 표면 거칠기 (Ra)와의 관계를 규명하였다. Pd 촉매 처리 시간이 길어질수록 Ni-P nodule의 면적은 넓어지고, Ni-P 도금의 표면 거칠기 (Ra)는 감소한다. 이러한 영향으로 질산 기상 처리한 시편의 high speed shear 평가후 quasi-brittle과 brittle 모드의 점유율은 감소한다. 이는 Pd 촉매 처리 시간의 증가가 SAC405 솔더조인트의 신뢰도를 향상시키는 역할을 한다는 것을 나타낸다.

• International Journal of Korean Welding Society
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• 제2권2호
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• pp.14-18
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• 2002

Titanium and titanium alloy are excellent in corrosion resistance and specific intensity, and also in the biocompatibility. On the other hand, the brazing is bonding method of which productivity and reliability are high, when the complicated and precise structure of the thin plate is constructed. However, though conventional titanium-based brazing filler metal was excellent in bond strength and corrosion resistance, it was disadvantageous that metal structure and mechanical property of the base metal deteriorated, since the brazing temperature ( about $1000^{\circ}C$ ) is considerably high. Authors developed new brazing filler metal which added Zr to Ti-Cu (-Ni) alloy which can be brazed at $900^{\circ}C$ or less about 15 years ago. In this paper, the development of more low-melting-point brazing filler metal was tried by the addition of the fourth elements such as Ni, Co, Cr for the Ti-Zr-Cu alloy. As a method for finding the low-melting-point composition, eutectic composition exploration method was used in order to reduce the experiment point. As the result, several kinds of new brazing filler metal such as 37.5Ti-37.5-Zr-25Cu alloy (melting point: $825^{\circ}C$) and 30Ti-43Zr-25Cu-2Cr alloy (melting point: $825^{\circ}C$) was developed. Then, the brazing joint showed the characteristics which were almost equal to the base metal from the result of obtaining metallic structure and strength of joint of brazing joint. However, the brazing filler metal composition of the melting point of $820^{\circ}C$ or less could not be found. Consequentially, it was clarified that the brazing filler metal developed in this study could be practically sufficiently used from results such as metal structure of brazing joint and tensile test of the joint.

• 한국도로학회논문집
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• 제15권5호
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• pp.47-55
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• 2013

PURPOSES : The purpose of this study is to investigate the optimal joint positions which can minimize distresses of concrete pavement containing box culvert with horizontally skewed angles. METHODS : The concrete pavement containing the box culvert with different skewed angles and soil cover depths was modeled by 3 dimensional finite element method. The contact boundary condition was used between concrete and soil structures in addition to the nonlinear material property of soil in the finite element model. A dynamic analysis was performed by applying the self weight of pavement, negative temperature gradient of slab, and moving vehicle load simultaneously. RESULTS : In case of zero skewed angle ($0^{\circ}$), the maximum tensile stress of slab was the lowest when the joint was positioned directly over side of box culvert. In case there was a skewed angle, the maximum tensile stress of slab was the lowest when the joint passed the intersection between side of the box culvert and longitudinal centerline of slab. The magnitude of the maximum tensile stress converged to a constant value regardless the joint position from 3m of soil cover depth at all of the horizontally skewed angles. CONCLUSIONS : More reasonable and accurate design of the concrete pavement containing the box culvert can be possible based on the research results.