https://scholarworks.unist.ac.kr/handle/201301/129 2026-04-19T03:17:52Z https://scholarworks.unist.ac.kr/handle/201301/11983 Title: 자동차 가상생산 기술 적용(Ⅲ) - 가상 도장공장 구축 및 운영 Author(s): Kim, Duck Young; 노상도; 박영진 2002-11-30T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/11976 Title: Compatibility measurement in collaborative conceptual design Author(s): Kim, Duck Young; Bufardi, A; Xirouchakis, P Abstract: A product consists of various sub-functions elaborated by alternative design principles which results in many combinations. In collaborative design, designers expect that their preferences over the combinations be respected during the combination process of sub-functions, resulting in compatible combinations. We formulate the selection of compatible combinations as a combinatorial problem by: (i) defining a design principle as a list of variables with their domain and direction of designer's preferences, (ii) considering constraints among design principles, (iii) characterizing the compatibility level of combinations. A vacuum cleaner is considered with dust bag, plastic bin or cyclonic design principles for the dust collection sub-function. 2006-11-30T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/8405 Title: Early Detection of Interconnect Degradation by Continuous Monitoring of RF Impedance Author(s): Kwon, Daeil; Azarian, Michael H.; Pecht, Michael Abstract: Traditional methods used to monitor interconnect reliability are based on measurement of dc resistance. DC resistance is well suited for characterizing electrical continuity, such as identifying an open circuit, but is not useful for detecting a partially degraded interconnect. Degradation of interconnects, such as cracking of solder joints due to fatigue or shock loading, usually initiates at an exterior surface and propagates toward the interior. At frequencies above several hundred megahertz, signal propagation is concentrated at the surface of interconnects, a phenomenon known as the skin effect. Due to the skin effect, RF impedance monitoring offers a more sensitive and reproducible means of sensing interconnect degradation than dc resistance. Since the operation of many types of electronic product requires transmission of signals with significant frequency components in the gigahertz range, this has the further implication that even a small crack at the surface of an interconnect may adversely affect the performance of current and future electronics. This paper demonstrates the value of RF impedance measurements as an early indicator of physical degradation of solder joints as compared to dc-resistance measurements. Mechanical fatigue tests have been conducted with an impedance-controlled circuit board on which a surface mount component was soldered. Simultaneous measurements were performed of dc resistance and time domain reflection coefficient as a measure of RF impedance while the solder joints were stressed. The RF impedance was observed to increase in response to the early stages of cracking of the solder joint while the dc resistance remained constant. Failure analysis revealed that the RF impedance increase resulted from a physical crack, which initiated at the surface of the solder joint and propagated only partway across the solder joint. A comparison between RF impedance and event detectors was made to compare their respective sensitivities in detecting interconnect degradation. These test results indicate that RF impedance can serve as a nondestructive early indicator of solder joint degradation and as an improved means for assessing reliability of high-speed electronics. 2009-05-31T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/16762 Title: Computational analysis of a molten-salt electrochemical system for nuclear waste treatment Author(s): Kim, K. R.; Choi, S. Y.; Ahn, D. H.; Paek, S.; Park, B. G.; Lee, H. S.; Yi, K. W.; Hwang, I. S. Abstract: This paper describes ongoing research into the multi-physics model development of an electrorefining process for the treatment of spent nuclear fuel. A forced convection of molten eutectic (LiCl-KCl) electrolyte in an electrorefining cell is considered to establish an appropriate electro-fluid model within the 3-dimensional framework of a conventional computational fluid dynamic model. This computational platform includes the electrochemical reaction rate of charge transfer kinetics which is described by a Butler-Volmer equation, while mass transport is considered using an ionic transport equation. The coupling of the local overpotential distribution and uranium concentration gradient makes it possible to predict the local current density distribution at the electrode surfaces 2009-10-31T15:00:00Z