• Journal of the Microelectronics and Packaging Society
• /
• v.9 no.1
• /
• pp.35-41
• /
• 2002

Flip-chip interconnection that uses solder bump is an essential technology to improve the performance of micro-electronics which require higher working speed, higher density, and smaller size. In this paper, the shear strength of Cr/Cr-Cu/Cu UBM structure of the high-melting solder bump and that of low-melting solder bump after aging is evaluated. Observe intermetallic compound and bump joint condition at the interface between solder and UBM by SEM and TEM. And analyze the shear load concentrated to bump applying finite element analysis. As a result of experiment, the maximum shear strength of Sn-97wt%Pb which was treated 900 hrs aging has been decreased as 25% and Sn-37wt%Pb sample has been decreased as 20%. By the aging process, the growth of $Cu_6/Sn_5$ and $Cu_3Sn$ is ascertained. And the tendency of crack path movement that is interior of a solder to intermetallic compound interface is found.

• Women's Health Nursing
• /
• v.20 no.1
• /
• pp.48-61
• /
• 2014

Purpose: This study was done to explore the essence and meaning of the experience of 'aging', as a process of 40's and 50's women in Korea by applying the Parse's Human Becoming theory (2002). Methods: Data was collected from February to April, 2013, using the phenomenological research method. Data was collected through in-depth informal interview and analyzed following Colaizzi method. After IRB permission and informed consent from the participants, all interviews were recorded with MP3 recorder and transcribed for analysis. Results: Data analysis revealed 112 of meanings, 33 key subject words, 8 subject phrases, and 4 categories. The main themes were elaborated as 'going down' ('Being changed of body and mind', 'Being considered on my identity'), 'going up' ('Being expanded of productive role', 'Being transcendent multi-dimensionally'), 'pausing' ('Becoming more thoughtful about family', 'Looking back'), 'going forward again' ('Age is just a number, 'Contemplating of life and death'). Experiences in aging among women in 40's and 50's enlightened with Parse's theory of Human Becoming in terms of 'going down', 'going up', 'pausing', 'going forward again' appeared simultaneously, rather than consecutively. Conclusion: Women in 40's and 50's require holistic nursing intervention with physical, psychological, socio-economical, and spiritual aspects, rather than focusing on problematic physical symptom relief and prevention of further conditions. It is recommended to develop various nursing intervention considering on different environment, type of experience, and level of human becoming, individually.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.32 no.1
• /
• pp.6-12
• /
• 2019

Bonding properties of epoxy-containing solder joints were investigated by a high temperature aging test. Specimens were prepared by bonding an R3216 standard chip resistor to an OSP-finished PCB by a reflow process with two basic types of solder (SAC305 & Sn58Bi) pastes and two epoxy-solder (SAC305+epoxy & Sn58Bi+epoxy) pastes. In all epoxy solder joints, an epoxy fillet was formed in the hardened epoxy, lying around the outer edge of the solder joint, between the chip and the Cu pad. In order to analyze the bonding characteristics of solder joints at high temperatures, a high-temperature aging test at $150^{\circ}C$ was carried out for 14 days (336 h). After aging, the intermetallic compound $Cu_6Sn_5$ was found to have formed in the solder joint on the Cu pad, and the shear stress on the conventional solder joint was reduced by a significant amount. The reason that the shear force did not decrease much, even though in epoxy solder, was thatbecause epoxy hardened at the outer edge of the supported solder joints. Using epoxy solder, strong bonding behavior can be ensured due to this resistance to shear force, even in metallurgical changes such as those where intermetallic compounds form at solder joints.

• The Korea Journal of Herbology
• /
• v.24 no.4
• /
• pp.101-106
• /
• 2009

Objectives : We investigated the anti-aging effects on skin with 9 Repetitive steaming and fermenting herbal composition extract (FHE). Methods : Herbal composition is comprised of Panax Ginseng, Rehmannia glutinosa, Polygonum multiflorum and Polygonatum Sibiricum. They steamed and fermented with Saccharomyces cerevisiae and Lactobacillus brevis by turns at 9 times. We measured various effects related to skin aging such as scavenging activity against free radical, cell proliferation, collagen synthesis and toxicity of 9 repetitive steaming and fermenting herbal composition extract were evaluated and compared with herbal composition extract (HE). Results : As the number of steaming and fermenting cycle increased free-radical scavenging activity were increased. But cell proliferating ratio was not increased when the number of steaming and fermenting cycle. The FHE could significantly increase the collagen synthetic ratio compared with HE treated group. And, FHE was showed no toxicity at all tested concentrations. Conclusions : The results of our study propose that FHE has good anti-aging effects on skin.

• Nuclear Engineering and Technology
• /
• v.54 no.11
• /
• pp.4111-4124
• /
• 2022

The control rod drive system is critical to the reactor's reliable operation. The performance of its control system and mechanical system will gradually deteriorate because of operational and environmental stresses, thus increasing the reactor's operational risk. Currently there are few researches on the aging-related degradation of the entire control rod drive system. Because it is difficult to quantify the effect of various environmental stresses and establish an accurate physical model when multiple mechanisms superimposed in the degradation process. Therefore, this paper investigates the aging-related degradation of a control rod drive system by integrating Dynamic Object-Oriented Bayesian Network and Hidden Markov Model. Uncertainties in the degradation of the control system and mechanical system are addressed by using fuzzy theory and the Hidden Markov Model respectively. A system which consists of eight control rod drive mechanisms divided into two groups is used to demonstrate the method. The aging-related degradation of the control rod drive system is analyzed by the Bayesian inference algorithm based on the accelerated life test data, and the impact of different operating schemes on the system performance is also investigated. Meanwhile, the components or units that have major impact on the system's performance are identified at different operational phases. Finally, several essential safety measures are suggested to mitigate the risk caused by the system degradation.

• Korean Journal of Materials Research
• /
• v.32 no.3
• /
• pp.161-167
• /
• 2022

A cold roll-bonding process is applied to fabricate an AA6061/AA5052/AA6061/AA5052 layered sheet. Two AA6061 and one AA5052 sheets of 2mm thickness, 40mm width and 300mm length are alternately stacked, then reduced to a thickness of 2.0 mm by multi-pass cold rolling after surface treatment such as degreasing and wire brushing. The rolling is performed at ambient temperature without lubricant using a 2-high mill with a roll diameter of 400 mm at a rolling speed of 6.0 m/sec. The roll-bonded AA6061/AA5052/AA6061/AA5052 layered sheet is then hardened by natural aging (T4) and artificial aging (T6) treatments. The microstructure of the as-roll bonded and the age-hardened Al sheets was revealed by SEM observation; the mechanical properties were investigated by tensile testing and hardness testing. After T4 and T6 aging treatment, the specimens had a recrystallization structure consisting of coarse equiaxed grains in both AA5052 and AA6061 regions. The as-roll-bonded specimen showed a clad structure in which the hardness of AA5052 regions was higher than that of AA6061 regions. However, after T4 and T6 aging treatment, specimens exhibited different structures, with hardness of AA6061 regions higher than that of AA5052 regions. Strengths of T6 and T4 age-treated specimens were found to increase by 1.55 and 1.36 times, respectively, compared to the value of the starting material.

• Korean Journal of Materials Research
• /
• v.33 no.12
• /
• pp.565-571
• /
• 2023

AA1050/AA6061/AA1050 layered sheet was fabricated by cold roll-bonding process and subsequently T4 and T6 aging-treated. Two commercial AA1050 sheets of 1 mm thickness and one AA6061 sheet of 2 mm thickness were stacked up so that an AA6061 sheet was located between two AA1050 sheets. After surface treatments such as degreasing and wire brushing, they were then roll-bonded to a thickness of 2 mm by cold rolling. The roll-bonded Al sheets were then processed by natural aging (T4) and artificial aging (T6) treatments. The as roll-bonded Al sheets showed a typical deformation structure, where the grains are elongated in the rolling direction. However, after the T4 and T6 aging treatments, the Al sheets had a recrystallized structure consisting of coarse grains in both the AA5052 and AA6061 regions with different grain sizes in each. In addition, the sheets showed an inhomogeneous hardness distribution in the thickness direction, with higher hardness in AA6061 than in AA1050 after the T4 and T6 age treatments. The tensile strength of the T6-treated specimen was higher than that of the T4-treated one. However, the strength-ductility balance was much better in the T4-treated specimen than the T6-treated one. The tensile properties of the Al sheets fabricated in the present study were compared with those in a previous study.

• Korean Chemical Engineering Research
• /
• v.46 no.3
• /
• pp.545-549
• /
• 2008

The surface characteristics of calcined ${\gamma}-Al_2O_3$ particles as well as ${\gamma}-AlO$(OH) sol particles were controlled by aging in the boehmite sol preparation. As a result of the study, the IEPs of ${\gamma}-AlO$(OH) particles were decreased from pH 9.25 to pH 8.70 and those of the calcined ${\gamma}-Al_2O_3$ particles were decreased from pH 9.90 to pH 8.86 by the increase of the aging times. As a result of the acidic and basic characterization of the calcined ${\gamma}-Al_2O_3$ particles by the aging, the amount of acid sites was decreased from 0.1367 mmol/g to 0.0783 mmol/g by the increase of the aging times and Hammett acidity, $H_o$ was showed the acidic strength of 4.8 or above. On the other hand, the amount of basic sites was decreased from 0.4399 mmol/g to 0.3074 mmol/g by the increase of the aging times. Based on these results, we proposed the fact that the aging step in the sol-gel process was an important step to control the surface characterization of ${\gamma}-Al_2O_3$ particles including acidity and basicity.

• Proceedings of the KIEE Conference
• /
• 1995.11a
• /
• pp.352-354
• /
• 1995

The optical and electrical properties of High Speed AlGaAs infrared LED by using metal wet etch process instead of metal lift-off process are investigated. The power out increases when metal contact is patterned by wet etch process. Forward voltage and Reverse voltage for metal wet etch process represent higher value than the metal lift-off process. The aging effect of power out also indicates good results with wet etch process. The wet etch process for metal contact reveals reliable LED device properties.

• Journal of the Korean association of regional geographers
• /
• v.15 no.1
• /
• pp.36-52
• /
• 2009

Demographic change is the best indicator to be able to show the rural change exactly and thus becomes the factor to be considered by all means in the setting-up process of the rural development policy. First of all, this paper is concerned with the two main themes, depopulation and aging process of Goryeong-gun(county), after a brief consideration of the demographic trends in rural areas of Korea. And then it will analyze the population structures of 8 administrative districts of Goryeong-gun(1 Eub, 7 Myeons) to reveal the areal differentiation of rural demographic change. Like other rural areas in Korea, Goryeong-gun experienced a sharp depopulation and aging during last several decades, and it represents typical rural backward areas in Korea. But within the same county, the process of population change differs from district to district. On the basis of several demographic indicators, 8 administrative districts(Eub and Myeons) in Goryeong-gun can be classified into 4 types of population change, namely 'type with stagnant population' like Goryeong-eub, 'type with increasing population' like Dasan-myeon, 'type with decreasing population' like Seongsan-myeon Gaejin-myeon Sangrim-myeon, 'type with rapidly decreasing population' like Deokgok-myeon Unsu-myeon Ugok-myeon. It highlights the need to develop differentiated rural policies according to relevant regional conditions.