• JSTS:Journal of Semiconductor Technology and Science
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• 제3권3호
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• pp.122-131
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• 2003

In this study, some characteristics of conductive and non-conductive adhesive inter-connections are derived, based on data from literature and own projects. Assembly of flip chip on flex is taken as a carrier. Potential failure mechanisms of adhesive interconnections reported in literature are reviewed. Some methods that can be used to evaluate the quality of adhesive interconnections and to evaluate their aging behavior are given. Possible finite element simulation approaches are introduced and the required critical materials properties are summarized. Response to temperature and moisture, resistance to reflow soldering and resistance to rapid change in temperature and humidity are elaborated. The effect of post cure during accelerated testing is discussed. This study shows that only a combined approach using finite element simulations, and use of appropriate experimental evaluation methods can result in revealing, understanding and quantifying the complex degradation mechanisms of adhesive interconnections during aging.

• 한국농공학회논문집
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• 제47권6호
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• pp.27-34
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• 2005

The purpose of this study is to improve the durability performance of polymer modified cement composites for repair of concrete under combined aging conditions. The experimental procedure was divided into three parts. First, the replacement level of mineral admixtures in polymer modified cement composites were determined in an experimental study based on a Box Behnken design. Second, the flow value, compressive strength and chloride permeability test of sixteen types of mixtures were conducted. Test results show that the polymer modified cement composites were effected on the improvement of the compressive strength and permeability performance. Third, the effects on the replacement level of silica fume mixture was evaluated by the compressive strength, chloride permeability, chemical resistance and repeated freezing and thawing cycles test. They demonstrated that the polymer modified cement composites using mixture of silica fume, fly ash, and blast furnace slag improved the durability performance.

• Corrosion Science and Technology
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• 제15권4호
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• pp.159-165
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• 2016

An attempt has been made to understand the influence of retrogression and re-aging (RRA) on the exfoliation corrosion behaviour of AA 7085 alloy in comparison with the peak aged condition (PA). Immersion tests using ASTM G34 and studies involving electrochemical impedance spectroscopy showed that the RRA treated alloy provided higher resistance to exfoliation corrosion than the PA treated alloy. The improved resistance was attributed to the enhanced Cu content and the discontinuous nature of the grain boundary precipitate, which was revealed through transmission electron microscopy.

• Elastomers and Composites
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• 제7권1호
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• pp.45-52
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• 1972

As a series of the studies of EPDM-Polymer blends, the experiments are concentracted to the investigation of the physical properties of the EPDM-NBR blends. The results are shown as follows; 1. As EPDM addition ratio is increased, the physical properties such as resistance to ozone and aging have also improved, on the other hand, elongation and abrasion resistance decreased. 2. Tear strength is less influenced by blending and character after aging exhibited the same result. 3. Tensile strength decreased with increase in EPDM contents, especially the ratio of EPDM/NBR are 50/50 and 75/25.

• The Journal of Advanced Prosthodontics
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• 제14권3호
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• pp.173-181
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• 2022

PURPOSE. This analysis aimed to evaluate the intaglio surface trueness, antagonist's wear volume loss, and fracture resistance of full-contour crowns of (Y, Nb)-stabilized fully-sintered zirconia (FSZ), 4 mol% or 5 mol% yttria-stabilized partially sintered zirconia (4YZ or 5YZ) with high-speed sintering. MATERIALS AND METHODS. A total of 42 zirconia crowns were separated into three groups: FSZ, 4YZ, and 5YZ (n = 14). The intaglio surface trueness of the crowns was evaluated at the inner surface, occlusal, margin, and axial areas and reported as root-mean-square, positive and negative average deviation. Half of the specimens were aged for 120,000 cycles in the chewing simulator, and the wear volume loss of antagonist was measured. Before and after chewing, the fracture load was measured for each group. The trueness values were analyzed with Welch's ANOVA, and the wear volume loss with the Kruskal-Wallis tests. Effect of the zirconia type and aging on fracture resistance of crowns was tested using two-way ANOVA. RESULTS. The intaglio surface trueness measured at four different areas of the crown was less than 50 ㎛, regardless of the type of zirconia. No significant P in wear volume loss of antagonists were detected among the groups (P > .05). Both the type of zirconia and aging showed statistically significant effects on fracture resistance (P < .05). CONCLUSION. The full-contour crowns of FSZ as well as 4YZ or 5YZ with high-speed sintering were clinically acceptable, in terms of intaglio surface trueness, antagonist's wear volume loss, and fracture resistance after simulated mastication.

• Journal of Ginseng Research
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• 제47권4호
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• pp.524-533
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• 2023

Background: Obesity is a risk factor for aging and many diseases, and the disorder of lipid metabolism makes it prominent. This study aims to investigate the effect of ginsenoside Rg1 on aging, lipid metabolism and stress resistance Methods: Rg1 was administered to Caenorhabditis elegans (C. elegans) cultured in NGM or GNGM. The lifespan, locomotory activity, lipid accumulation, cold and heat stress resistance and related mRNA expression of the worms were examined. Gene knockout mutants were used to clarify the effect on lipid metabolism of Rg1. GFP-binding mutants were used to observe the changes in protein expression Results: We reported that Rg1 reduced lipid accumulation and improved stress resistance in C. elegans. Rg1 significantly reduced the expression of fatty acid synthesis-related genes and lipid metabolism-related genes in C. elegans. However, Rg1 did not affect the fat storage in fat-5/fat-6 double mutant or nhr-49 mutant. Combined with network pharmacology, we clarified the possible pathways and targets of Rg1 in lipid metabolism. In addition, Rg1-treated C. elegans showed a higher expression of anti-oxidative genes and heat shock proteins, which might contribute to stress resistance Conclusion: Rg1 reduced fat accumulation by regulating lipid metabolism via nhr-49 and enhanced stress resistance by its antioxidant effect in C. elegans.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2013년도 춘계학술대회 논문집
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• pp.184-184
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• 2013

본 연구에서는 금 합금 도금층의 접촉저항에 미치는 첨가 합금원소의 영향을 조사하였다. 또한 표면실장을 위한 솔더링 공정에서 도금층에 가해지는 열이력이 접촉저항 값에 미치는 영향을 조사하기 위해서, $260^{\circ}C$에서 thermal aging을 실시한 후, 접촉저항을 측정하였다. 합금원소의 종류에 따라서 thermal aging후의 접촉저항 값이 변하는 요인을 조사하기 위해서 XPS를 이용하여 표면분석을 실시하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.317-320
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• 1997

The paper reports on a study of the influence of the size of the particles of alumina trihydrate(ATH) filler on the surface aging characteristics of ehylene propylene diene terpolymer(EPDM). A fixed 100pph concentration of the filler of ATH was used (or all particle sizes from 0.7 to 20$\mu\textrm{m}$, It is show that hysteresis of contact angle and leakage current increase with increasing particle size, whereas tracking resistance decrease with increasing particle size.

• 한국지반공학회논문집
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• 제21권8호
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• pp.13-26
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• 2005

모래의 aging현상은 점성토에 비하여 무시할 정도로 매우 작아서 1980년대 초까지는 거의 연구되지 않았다. 그러나 퇴적이나 교란 후 시간경과에 따라 관입저항치의 증가가 관찰되면서 현장시험을 중심으로 모래의 aging 효과에 대하여 활발한 조사가 이루어졌고, 최근에는 현장시험뿐만 아니라 실내시험에서도 여러 연구자들에 의해 모래의 aging 효과가 규명되어지고 있다. 본 연구에서는 모래의 비배수 반복전단거동에 대한 aging효과를 살펴보기 위해 낙동강 모래를 이용하여 상대밀도$(D_r)$, 압밀응력비$(K_c)$ 그리고 압밀시간을 달리하여 비배수 반복삼축압축시험을 실시하였다. 시험결과, 비배수 반복전단강도$(R_f)$는 압밀시간에 따라 증가한다는 사실을 확인할 수 있었다. 본 시험결과에서 나타난 aging 에 따른 $R_f$ 증가율을 이용하여 낙동강 모래지반의 지진규모별 비배수 반복전단강도의 현장적용 범위를 제안하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.539-542
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• 2003

Recently, the polymer insulators which are being used for high voltage applications have some advantages such as light weight, small size, vandalism resistance, hydrophobicity and easy making process. During outdoor service of polymer insulators, the surface of the insulating material is frequently subjected to moisture and contamination which lead to the well known phenomenon of dry band arcing. Their tracking resistance, erosion resistance, end sealing and shed design are very important because dry band arcing causes degradation of polymer surface. The shape design of porcelain insulator is formalized but design standard for polymer insulator is no standardized up to now, much research is necessary in real condition. In this paper, the aging property of polymer insulator with shed shape(regular, alternative type) is analyzed through numerical analysis, CEA(canadian electricity association) tracking wheel test and IEC 61109 Annex C.