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유중돈,Yoo, Choong-D. 대한용접접합학회 2008 대한용접·접합학회지 Vol.26 No.1
초음파 용접용 혼의 설계에 대한 기본적인 방법과 절차를 설명하였다. 그러나 아직까지 혼의 최적 형상을 구하는 방법은 시행착오(trial-and-error) 방법과 실험 및 설계자의 경험에 많이 의존해야 한다. 또한, 혼의 해석 결과로서 다양한 진동 모드를 얻을 수 있기 때문에 설계자는 이를 분석하고 원하는 진동 모드를 얻을 수 있도록 설계하여야 한다.
유중돈 대한용접접합학회 2004 대한용접·접합학회지 Vol.22 No.4
마이크로 접합 공정은 미세 부품이나 박판의 접합에 사용되며, 이를 위해 다양한 공정이 개발되었다. 최근 MEMS(Micro Electro Mechanical System)활용 범위가 증가하고 있으며, MEMS에 사용되는 미세한 구조물의 접합이나 패키징에 접합 공정이 활용되고 있다. MEMS는 발전 단계이지만 전자 패키징(electronic packaging)은 성숙 단계인 반도체 산업에 사용되고 있다.(중략)
유중돈,Yoo, Choong-Don 대한용접접합학회 2007 대한용접·접합학회지 Vol.25 No.6
GMA 용접 시스템을 시뮬레이션 하기 위한 요소 기술과 문제점에 대하여 간단하게 설명하였다. 현재까지의 연구 결과로부터 GMA 용접 시스템을 해석하는데 필요한 원리 및 기본 방정식은 거의 알려진 상태이지만, 이와 같은 시뮬레이션은 이상적인 조건에서 계산한 결과로서 실제와는 차이가 발생한다. 이와 같은 오차는 실험을 통하여 지속적으로 수정 및 보완되어야 시뮬레이션의 정확도를 향상시킬 수 있으며, 향후 시뮬레이션이 용접 생산성과 품질을 향상시키는 도구로 활용될 수 있기를 기대한다.
유중돈 대한용접접합학회 1993 대한용접·접합학회지 Vol.11 No.2
Weld pool oscillation for the full-penetration GTA welding process was investigated for its possible application to weld penetration control through theoretical modeling and experiment. Energy method was used to estimate the natural frequency of the molten pool having the physically-acceptable weld geometry and oscillation modes. An unique experimental system was built which had the data acquisiton and video capabilities so that the pool oscillation signals and molten pool surfaces could be monitored continuously. Pool oscillation was detected through arc voltage and arc light emission simultaneously. The signal from arc light emission showed good coherence with that from arc voltage, and arc light generated the higher quality signal. The molten pool was found to oscillate in different oscillation modes based on the travel speed and weld geometry. The natural frequency estimated from the theoretical model agreed reasonably well with the experimental results.
워킹이 Gullwing 리드의 솔더 접합부 형상에 미치는 영향
최동필,유중돈,이태수,최상균 대한용접접합학회 1998 대한용접·접합학회지 Vol.16 No.4
During the reflow process in SMT, the molten solder has been observed to move upward and solidify along the gullwing lead, which is called the wicking phenomenon. In this paper, possible causes of the wicking are investigated, and its effects on the solder joint profile are quantitatively estimated by introducing the wicking constant. The free energy reduction by intermetallic formation between the copper and tin seems to be the major source of wicking action. The joint profiles of the gullwing lead are calculated using the previous finite element formulation incorporated with the wicking constant. The calculated results show reasonably good agreements with the experimental data when the wicking effects are considered.
Pulsed-GMAW의 금속 이행 현상에 관한 동적 해석
최상균,유중돈,박상규 대한용접접합학회 1997 대한용접·접합학회지 Vol.15 No.5
The metal transfer phenomenon of the pulsed-GMAW is simulated by formulating the electromagnetic force incorporated with the Volume of Fluid algorithm. The free surface profiles, pressure and velocity distributions within the drop are computed numerically. Axial velocity and acceleration generated during peak current period are found to have a significant effect on drop detachment. Therefore, the accelerated inertia force becomes one of important factors affecting metal transfer in the pulsed-GMAW. When the pulse current parameters are selected properly, the molten drop is detached just after current pulse, and the operating range of the pulsing frequency increases with higher peak current and duty cycle. Calculated operating ranges show reasonably good agreements with the available experimental data.
CD 스터드 용접의 해석 및 결함 분석 Part 2 : 기공 제어
오현석,유중돈,Oh Hyun-Seok,Yoo Choong-D. 대한용접접합학회 2006 대한용접·접합학회지 Vol.24 No.3
Since the voids occur at the CD stud welds, the mechanism of void formation and void reduction method are investigated in this work. It is speculated that the voids are formed because of high short-circuit current above 1000A. When the simple flow model is used to estimate the void trapping condition, the most voids are trapped at the weld mainly due to fast cooling rate of the CD stud weld. Since it is almost impossible to remove the voids completely, a method is proposed to reduce the void by decreasing the short-circuit current at the end of the arcing time. The experimental results show that the void is reduced by decreasing the short-circuit current to 1000A.
CD 스터드 용접의 해석 및 결함 분석 Part 1 : 공정 모델링과 해석
오현석,유중돈,Oh Hyun-Seok,Yoo Choong-D. 대한용접접합학회 2006 대한용접·접합학회지 Vol.24 No.3
The CD (Capacitor Discharge) stud welding utilizes the arc heat and pressure to attach the stud to the workpiece, which consists of the arc. ignition, arcing and pressure welding stages. In order to predict the dynamic behavior of the CD stud welding process, mechanical and electrical models are employed in this work. While the mechanical model estimates the duration of each stage, the electrical model predicts the voltage and current waveforms using the RLC circuit. Effects of process parameters such as the electric components and spring force are analyzed through simulation. It is found that the contact resistance and gap between the stud and base metal influence the tip fusing and arcing duration. The calculated results showed reasonably good agreements with the experiment results.