• Title/Summary/Keyword: Immersion test

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Effect of PCB Surface Finishs on Intermetallic Compound Growth Kinetics of Sn-3.0Ag-0.5Cu Solder Bump (Sn-3.0Ag-0.5Cu 솔더범프의 금속간화합물 성장거동에 미치는 PCB 표면처리의 영향)

  • Jeong, Myeong-Hyeok;Kim, Jae-Myeong;Yoo, Se-Hoon;Lee, Chang-Woo;Park, Young-Bae
    • Journal of the Microelectronics and Packaging Society
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    • v.17 no.1
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    • pp.81-88
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    • 2010
  • Thermal annealing and electromigration test were performed at $150^{\circ}C$ and $4{\times}10^3\;A/cm^2$ conditions in order to investigate the effect of PCB surface finishs on the growth kinetics of intermetallic compound (IMC) in Sn-3.0Ag-0.5Cu solder bump. The surface finishes of the electrodes of printed circuit board (PCB) were organic solderability preservation (OSP), immersion Sn, and electroless Ni/immersion gold (ENIG). During thermal annealing, the OSP and immersion Sn show similar IMC growth velocity, while ENIG surface finish had much slower IMC growth velocity. Applying electric current accelerated IMC growth velocity and showed polarity effect due to directional electron flow.

The Influence of the Early Childhood Teacher's Play Teaching Efficacy and Play Sensitivity on Young Children's Play Flow (유아교사의 놀이교수효능감 및 놀이 민감성이 유아의 놀이몰입에 미치는 영향)

  • In-Sook Choi
    • Journal of the Health Care and Life Science
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    • v.11 no.1
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    • pp.49-57
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    • 2023
  • The purpose of this study is to analyze the relationship between early childhood teachers' play teaching efficacy and play sensitivity and children's play immersion, and to investigate the effect of play teaching efficacy and play sensitivity on children's play immersion. To this end, a survey was conducted targeting 359 early childhood teachers working in kindergartens and daycare centers located in J province. The research tools used in this study were 'Efficacy in Play Teaching' and 'Teacher's Play Sensitivity Scale' targeting teachers and 'Infant Play Immersion Test' targeting infants. As a result of the study, first, the correlation between play teaching efficacy and play sensitivity and young children's play immersion showed that there was a positive correlation between all variables other than the transformation of the sense of time among the teacher's play sensitivity sub-factors and play observation and children's play immersion sub-factors. Second, as a result of examining the effect of teacher's play teaching efficacy and play sensitivity on young children's play immersion, it was found to have a partially statistically significant effect.

Determination of the elastic properties in CFRP composites: comparison of different approaches based on tensile tests and ultrasonic characterization

  • Munoz, Victor;Perrin, Marianne;Pastor, Marie-Laetitia;Welemane, Helene;Cantarel, Arthur;Karama, Moussa
    • Advances in aircraft and spacecraft science
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    • v.2 no.3
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    • pp.249-261
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    • 2015
  • The mechanical characterization of composite materials is nowadays a major interest due to their increasing use in the aeronautic industry. The design of most of these materials is based on their stiffness, which is mainly obtained by means of tensile tests with strain gauge measurement. For thin laminated composites, this classical method requires adequate samples with specific orientation and does not provide all the independent elastic constants. Regarding ultrasonic characterization, especially immersion technique, only one specimen is needed and the entire determination of the stiffness tensor is possible. This paper presents a study of different methods to determine the mechanical properties of transversely isotropic carbon fibre composite materials (gauge and correlation strain measurement during tensile tests, ultrasonic immersion technique). Results are compared to ISO standards and manufacturer data to evaluate the accuracy of these techniques.

Effect of Temperature and Water Immersion on Strength Properties of Spot Welded Zincked Steel Plates (점용접 아연도금강판의 강도특성에 미치는 온도 및 침수의 영향)

  • Seo, Do-Won;Choi, Jun-Yong;Lim, Jae-Kyoo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.12
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    • pp.1864-1870
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    • 2004
  • A spot welded structures have an influence on a diverse climatic situation, for instance temperature, humidity and precipitation. In addition factors of environmental pollution such as acid rain, that courses corrosion, have the tendency to increase. But spot welded structures strength is affected by humidity and environment temperature. Therefore, it is important to evaluate effect of temperature and water immersion on strength properties of spot welded part. In this study, the strength distribution of spot welded plates is evaluated the environmental temperature of zinc coated steel plates. Test is conducted with welded part immersed in distilled and synthetic sea water. Specimens are immersed into water for 10, 100, 500 and 1000 hours to evaluate the offsets of water immersion time on tensile-shear strength under the conditions of -40, 0, 20 and 5$0^{\circ}C$. From this result, spot welded specimens with 5 mm clearance have lower tensile-shear strength in the distilled water or synthetic sea water than without clearance. And they have lower tensile-shear strength under -4$0^{\circ}C$ and over 5$0^{\circ}C$.

Effectiveness of Learning Performances According to Financial Motivation of University Students

  • PARK, Young-Sool;KWON, Lee-Seung;CHOI, Eun-Mee
    • Asian Journal of Business Environment
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    • v.9 no.3
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    • pp.27-38
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    • 2019
  • Purpose - The aim of this study is to explore the effectiveness in educational differences between students of the government's financial-funded groups and the non-financial-funded groups at a university in Korea. Research design, data, and methodology - The study was conducted using a survey tool of National Assessment for Student Engagement in Learning. In total, 334 participants were surveyed, of which 290 students were participants in economic support program and 44 were nonattendance program students. The general characteristics of all of the participants were investigated by frequency analysis. The analysis of participants' collective characteristics used independent t and f-test, and one-way ANOVA with IBM SPSS Statistics package program 22.0. Results - The number of participating students is higher than that of non-participating students in relation to in-activities of university immersion, but the number of participating students is lower than that of non-participating students in relation to in-quality of student support. However, there was no statistical significance. The confidence coefficient of the university-immersion and student support questionnaire is 0.860 and 0.913, respectively. Conclusions - There is no significant difference in the activities of university immersion and student support between students who participate in the economic support program and those who do not.

A Study on the Adhesion Improvement of Immersion Copper Coatings using Complexing Agent (착화제를 이용한 치환동 도금층의 밀착력 향상에 관한 연구)

  • Koo, Seokbon;Jeon, Jumi;Hur, Jinyoung;Lee, Hongkee
    • Journal of the Korean institute of surface engineering
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    • v.48 no.1
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    • pp.1-6
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    • 2015
  • Amino-carboxyl acid as a complexing agent in acid copper sulfate solution was utilized to improve the adhesion of immersion copper layer for steel wire. According to the tape test results, regardless of alloy composition of the wire, the adhesion of immersion copper layer was improved with the addition of amino-carboxyl acid. The incorporation of H and Fe in the plating layer was analyzed by TOF-SIMS. The H and Fe were detected at the entire coating layer without any addition of amino-carboxyl acid. However, with addition of amino-carboxyl acid, the H and Fe were scarcely detected at the coating layer.

How Customers Perceive Virtual Mirror Technology in the 4th Industrial Revolution Environment

  • JO, Junghee;CHO, Yoon C.
    • The Journal of Economics, Marketing and Management
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    • v.10 no.4
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    • pp.1-12
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    • 2022
  • Purpose: The purpose of this study is to explore how customers perceive virtual mirror technology in the 4th industrial revolution environment. In particular, this study investigated how virtual mirror technology affects customer satisfaction and intention to use that are rarely examined in previous studies. Research questions include how proposed variables including sensory stimulation, enjoyment, product quality, telepresence, interactivity, and immersion affect satisfaction and intention to use and how satisfaction affects intention to use. Research design, data and methodology: This study conducted an online survey and applied factor and regression analyses to test hypotheses. Results: The results of this study found that effects of sensory stimulation, telepresence, and immersion on satisfaction were significant, while effects of enjoyment, product quality, and immersion on intention to use were significant. Therefore, variables affecting satisfaction and intention to use were different, while effects of immersion were significant both on satisfaction and intention to use. Conclusions: This study concluded that the role of virtual mirror technology helps customers determine product quality and increase satisfaction level, while it also helps customers enjoy shopping and increase intent to use the service. The results of this study provide how to foster better relationship with customers by applying advanced technologies.

Factors Influencing Learning Immersion in College Remote Classes (대학생의 원격수업에서 학습몰입도에 미치는 영향요인)

  • Heeyoung Woo;Minkyung Gu
    • Journal of the Korean Society of School Health
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    • v.36 no.2
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    • pp.21-30
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    • 2023
  • Purpose: The study aimed to identify factors that affect college students' learning immersion in non-face-to-face remote classes. Methods: During COVID-19, a survey was conducted on 140 college students who were taking non-face-to-face remote courses at universities located in Seoul, Gyeonggi-do, and Chungcheong-do, Korea. Data were analyzed using the Pearson correlation coefficients, Independent t-test, ANOVA, and Hierarchial stepwise multiple regression with SPSS (Windows version 27.0). Results: In the study, the most important variable influencing learning immersion was the student's self-efficacy, followed by instructor presence, class participation, lecture satisfaction, and credits. Conclusion: Instructors who teach major courses at college need to develop and apply ways to enhance learners' self-efficacy and class content that can boost learners' motivation in order to maximize learners' learning immersion. In order to facilitate learners' access to online media and maintain their interest in remote classes, passionate efforts need to be made by active instructors.

Strength degradation of a natural thin-bedded rock mass subjected to water immersion and its impact on tunnel stability

  • Zhang, Yuting;Ding, Xiuli;Huang, Shuling;Wu, Yongjin;He, Jun
    • Geomechanics and Engineering
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    • v.21 no.1
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    • pp.63-71
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    • 2020
  • Strength anisotropy is a typical feature of thin-bedded rock masses and their strength will be degraded subjected to water immersion effect. Such effect is crucial for the operation of hydropower plant because the impoundment lifts the water level of upstream reservoir and causes the rock mass of nearby slopes saturated. So far, researches regarding mechanical property of natural thin-bedded rock masses and their strength variation under water immersion based on field test method are rarely reported. This paper focuses on a thin-bedded stratified rock mass and carries out field test to investigate the mechanical property and strength variation characteristics. The field test is highlighted by samples which have a large shear dimension of 0.5 m*0.5 m, representing a more realistic in-situ situation than small size specimen. The test results confirm the anisotropic nature of the concerned rock mass, whose shear strength of host rocks is significantly larger than that of bedding planes. Further, the comparison of shear strength parameters of the thin-bedded rock mass under natural and saturated conditions show that for both host rocks and bedding planes, the decreasing extent of cohesion values are larger than friction values. The quantitative results are then adopted to analyze the influence of reservoir impoundment of a hydropower plant on the surrounding rock mass stability of diversion tunnels which are located in the nearby slope bank. It is evaluated that after reservoir impoundment, the strength degradation induced incremental deformations of surrounding rock mass of diversion tunnels are small and the stresses in lining structure are acceptable. It is therefore concluded that the influences of impoundment are small and the stability of diversion tunnels can be still achieved. The finings regarding field test method and its results, as well as the numerical evaluation conclusions are hoped to provide references for rock projects with similar concerns.

The Effect of Classes Applying Non-face-to-face Havruta's Activities on Communication Competency, Academic Self-efficacy, and Learning Immersion in Nursing Students (비대면 하브루타 활동을 적용한 수업이 간호대학생의 의사소통능력, 학업적 자기효능감, 학습몰입에 미치는 효과 : 일개 대학 2학년 학생 대상으로)

  • Lee, Ji-Hye;Moon, Suk-Ja
    • Journal of Industrial Convergence
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    • v.20 no.7
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    • pp.79-88
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    • 2022
  • This study is a one group pretest-posttest design study to confirm the effect of non-face-to-face Havruta's activities on communication competency, academic self-efficacy, and learning immersion of nursing students. The study was conducted from September to October 2021. The collected data were through self-report questionnaires of 69 student nurses. The data were analyzed by frequencies and paired t-test using SPSS 24.0 program. As a result, the subjects' communication competency, academic self-efficacy, and learning immersion were significantly increased after the non-face-to-face Havruta's activities compared to before. The results of this study can be useful basic data for professors who want to apply non-face-to-face Havruta's activities to their classes in the future.