• Title/Summary/Keyword: Gap Effect

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An Experimental Study on the Characteristics of the High Temperature Superconductor as an Application of the Repulsive Type Magnetic Bearing (반발식 자기 베어링의 응용으로서 고온 초전도체의 특성에 관한 실험적 연구)

  • 유제환;임윤철
    • Tribology and Lubricants
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    • v.13 no.2
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    • pp.52-59
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    • 1997
  • An experimental study is presented for the characteristics of the high temperature superconductor as an application of the repulsive type magnetic bearing. A ring shaped YBCO type superconductor and Neodium permanent magnets are employed for the experiment. For the case of field cooling, superconductor shows strong repulsive force, which is due to the Meissner effect, as the gap between the superconductor and the magnet gets closer. The repulsive force variation with respect to the gap change shows hysterisis characteristics. The area of the loop of the hysterisis curve represents the dissipation of energy, which reveals that the magnetic bearing with superconductor has large damping. The effect of the initial gap and the magnetic flux density on the repulsive force is analyzed experimentally and the static stiffness variation is calculated from the measured repulsive force variation. The relative sliding velocity between the superconductor and the magnet has little effect on the repulsive force which is quite different from the usual sliding element bearing. As the initial gap for the field cooling becomes larger, the maximum repulsive force at the minimum gap increases and approaches to the value for the case of zero field cooling.

Effects of In-role Behaviour Gap on Interpersonal Behaviours Focused on the Mediating Effect of Stress

  • Song, Gi-Ryung;Kim, Kyoung-Seok
    • Asia-Pacific Journal of Business
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    • v.12 no.4
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    • pp.41-52
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    • 2021
  • Purpose - This study is to identify the relationship between the gap of in-role behaviour (IRB) on employee's interpersonal behaviour with the different perspective considering this behaviour as a social action that employees show in their work life, away from the perspective of conventional research that treats IRB as task performance. Design/methodology/approach - This study focus on the level of IRB gap that individuals have with their colleagues and its effect on the interpersonal behaviours such as helping and incivility instigation. The higher the level of difference, the more likely it would negatively affect their interpersonal behaviour through stress. The analysis was conducted on 250 employees of Korean companies through partial least squares structural equation modelling. Findings - The analysis shows that IRB gaps have a negative effect on employee's fully helping, and partly instigated incivility, in mediating stress. Implications based on the results of the study were presented in the conclusion. Research implications or Originality - The approaches and findings thus study showed are unique because most of existing studies have not tried to focus on the gap of in-role behaviour between employees and their colleagues. This study can give novels inspirations to other researchers in the related field.

The effects of farmers and fishers' digital information utilization level on Life satisfaction: Focusing on mediating effects of digital device use attitude (농어민의 디지털 정보 활용 수준이 삶의 만족도에 미치는 영향: 디지털기기 이용 태도를 매개변수로)

  • Jeon, Bong Chun;Yoon, Han Sung
    • The Journal of Information Systems
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    • v.33 no.1
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    • pp.69-90
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    • 2024
  • Purpose In this paper, among the four information vulnerable groups(disabled, elderly, low-income, farmers and fishermen), the mediating effect of digital device usage attitudes in the effect of digital information utilization level of farmers and fishermen with a large digital information gap with the general public on life satisfaction was verified. Design/methodology/approach This study summarizes existing research related to the digital information gap between farmers and fishermen, and the empirical analysis is based on hierarchical regression analysis based on the 2022 Digital Information Gap Report (survey data on 2,200 farmers and fishermen) published by the Korea Intelligence Information Society Promotion Agency. Among the four major information vulnerable groups (the disabled, the elderly, low-income groups, and farmers and fishermen), attitudes toward using digital devices were examined in terms of the impact of the level of digital information use on life satisfaction among farmers and fishermen, who have a relatively large digital information gap with the general public. It was verified as a mediating effect. Findings As a result of the empirical analysis, attitudes toward the use of digital devices were found to play a mediating role in the impact of the level of digital information use on life satisfaction.

Effect of Up-and-Down Torch Oscillation for Providing Uniform Heat Input along the Sidewall of Gap on Ultra Narrow Gap Welding (울트라 내로우 갭 용접에서 갭 내 고른 아크입열 분포를 위한 상ㆍ하 토치요동 효과)

  • 김두영;나석주
    • Journal of Welding and Joining
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    • v.21 no.3
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    • pp.85-91
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    • 2003
  • Narrow gap welding has many advantages over conventional V-grooved butt welding such as high productivity, small deformation and improved mechanical property of joints. With narrower groove gap, less arc heat input is expected will all the other advantages of narrow gap welding. The main defects of narrow gap welding include the lack of root fusion, convex bead surface and irregular surface, all of which have negative effects on the next welding pass. This paper suggests an up-and-down torch oscillation for ultra narrow gap welding with gap size of 5mm and investigates the proper welding conditions to fulfill the reliable and high welding quality. First, GMA welding model was suggested for ultra narrow gap welding system with Halmoy's model referenced for wire melting modeling. And the arc length in ultra narrow gap was defined. Secondly, based on the experimental results of up-and-down torch oscillation welding, phase shift of current and wire extension length were simulated for varying oscillation frequency to show that weld the bead shape in ultra narrow gap welding can be predicted. As the result, it was confirmed that reliable weld quality in ultra narrow gap welding can be achieved with up-and-down torch oscillation above 15Hz due to its ability to provide uniform heat input along the sidewall of gap.

Evaluation of Reductive Effect of Exposure Dose by Using Air Gap Apron in Nuclear Medicine Related Work Environment (핵의학과 내 작업 환경에서 공기층 납치마의 피폭선량 감소 효과 평가)

  • Lee, Wang-Hui;Ahn, Sung-Min
    • The Journal of the Korea Contents Association
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    • v.14 no.12
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    • pp.845-853
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    • 2014
  • In this study, we measured the dose reaching the OSLD dosimeter by using the regular lead apron, and air gap apron through 3 experiments, and researched the reductive effect of air gap apron on exposure dose based on the 140 keV gamma ray radiating from $^{99m}technetium$, which is the most commonly used in nuclear medicine. As a result, when the gap between the dosimeter and 0.2mm lead plate is 0 Cm, the average value of 10 dosimeters was 0.515 mSv, and when the gap between the dosimeter and lead plate is 20 Cm, the average value of 10 dosimeters was 0.138 mSv, which shows reductive effect of dose as much as 0.388 mSv. When the gap between the dosimeter and 0.5mm lead plate is 0 Cm, the average value of 10 dosimeters was 0.296 mSv, and when the gap between the dosimeter and lead plate is 20 Cm, the average value of 10 dosimeters was 0.075 mSv, which shows reductive effect of dose as much as 0.221 mSv. As we check the cumulative dosage for 3 days, the lead apron without air layer shows average 0.239 mSv, and the air gap apron shows 0.176 mSv, which is actually reduced by 0.062 mSv. As we check the cumulative dosage for a month, the lead apron without air layer shows 0.59 mSv, and the air gap apron shows 0.54 mSv, which is reduced by 0.05 mSv.

Study of supersonic flame acceleration within AN-based high explosive containing various gap materials (AN계열 화약의 다양한 Gap 실험을 통한 초음속 화염 전파 특성 연구)

  • Lee, Jin-Wook;Yoh, Jai-Ick
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2012.05a
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    • pp.342-349
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    • 2012
  • We study the gap effect on detonating high explosives using the characteristic acoustic impedance theory and numerical simulation. A block of charge embedded with multiple gap inserts is detonated at one end to understand the ensuing flame propagation through multiple gap materials. The present high-order multimaterial simulation provides meaningful validation of complex interface tracking algorithm as it is implemented in the SNU-Hydropack code.

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Effect of cement space on the marginal and internal fit of zirconia restorations fabricated by CAD/CAM system (시멘트 공간이 캐드캠 시스템으로 제작한 지르코니아 수복물의 변연과 내부 적합도에 미치는 효과)

  • Lee, Jung-Hwan;Ahn, Jae-Seok
    • Journal of Technologic Dentistry
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    • v.39 no.4
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    • pp.235-242
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    • 2017
  • Purpose: The aim of this study was to evaluate the marginal and internal gap of zirconia copings fabricated by CAD/CAM system and to research the effect of cement space on the fit of zirconia prosthesis. Methods: Zirconia copings were designed using 3shape software and then milled from presintered zirconia blocks by Kavo dental milling machine. The cement space was set at $0{\mu}m$ around the margins for all groups, and additional cement space appling 1 mm above the finish lines of tooth. The samples were classified into 4 groups according to the cement space setting(Cs-0, Cs-40, Cs-80, Cs-120). Replica technique used to investigate marginal and internal gap. The silicone film thickness was recorded using a optical microscope with image software analysis system at 75${\times}$magnification. The assessment performed on the six points in bucco-lingual and mesio-distal sections(4 groups, 10 copings per group, 12 measuring points per coping). The data were statistically analyzed with one-way ANOVA followed by pair-wise Tukey's post hoc tests(${\alpha}$<0.05). Results: Better marginal and internal fit values were exhibited by $80{\mu}m$ cement space. The results showed that different cement space values had statistically significant effect on the marginal and internal gap of zirconia copings(p<0.001). The gap of margin and axial wall area was smaller than that the gap of occlusal area in all groups(p<0.001). Conclusion : Effect of different cement spaces on the marginal and internal gap of zirconia copings.

Numerical Study of Gap Size Ratio Effect for Noncondensable Gas Ventilation in Condensers (응축기의 비응축 가스 배출 타입에 따른 틈 간격 비율의 영향에 대한 수치적 연구)

  • Je, Jun-Ho;Kim, Soo-Jea;Choi, Chi-Woong;Kim, Moo-Hwan
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.36 no.1
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    • pp.67-74
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    • 2012
  • A numerical analysis was carried out to estimate the effect of the gap size ratio on the performance of condensers under noncondensable gas ventilation using the porous medium approach (PMA). In the PMA, the details of the tube bundle in the condenser are considered to be those of a porous medium, and the flow resistance term is added in the momentum equation. Three-dimensional analysis of the condensation for a McAllister condenser was conducted with the PMA using Fluent and user-defined functions (UDFs). The gap size effect on the condensation was negligible under pure steam conditions. However, the gap size effect was dominant in condensation with noncondensable gas and external venting. As the gap size decreased, the condensation rate increased for noncondensable gas in an external venting system.

Drag Reduction Effect by a Self-Adjustable Splitter Plate on the Flow over a Circular Cylinder (원형실린더 후류내의 가동형 와류분할판에 의한 항력 감소효과)

  • 박운진
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.5
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    • pp.1262-1275
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    • 1993
  • The drag reduction effect of a freely-rotatable splitter plate was experimentally investigated in the 2-D wake behind a circular cylinder. By arranging the splitter plate to be aparted with a certain gap from the cylinder, the splitter plate was able to be aligned itself automatically to the flow direction in the tested range of 6.2$\times$$10^3$$\times$$10^4$. As a result, it was proven that the self-adjustable splitter plate always reduced effectively the drag imposed on the body against any arbitrary flow directions. In a specific range of Reynolds numbers, the drag reduction effect was dependent not only on the length of the splitter plate but also on the gap distance between the plate and the trailing edge of the body. For a splitter plate with a specific length, there existed a unique optimum range of gap distance to obtain successfully the drag reduction effect, however, the optimum range of gap distance was dependent on Reynolds number.

The Public and Private Sector Wage Gap Trend in Korea - New evidence from the fixed effect analysis - (고정효과 분석을 이용한 공무원과 민간부문 임금격차 추세 추정)

  • Han, Jong-suk
    • Journal of Labour Economics
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    • v.40 no.1
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    • pp.69-97
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    • 2017
  • This paper estimates the public and private sector wage gap trend from 2000 to 2014 using 'Korean Labor and Income Panel Study.' We account for unobserved fixed effect by using 1st differencing log wage in order to allow the gap to vary over time. Standard OLS estimates present the public sector wage is 10% higher than private sector on average. Moreover, the public sector wage premium displays the inverted V shape: sharply increasing up to 2006 and decreasing from 2007 to 2014. However, after controlling unobserved fixed effect, the public sector wage premium disappears and does not display the inverted V shape any more.

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