• Title/Summary/Keyword: dynamic impact factor

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Analysis of Suspension State Matrix to Improve L/UL Performance (로드/언로드 성능향상을 위한 서스펜션 상태행렬의 해석)

  • Kim, Ki-Hoon;Lee, Young-Hyun;Park, Kyung-Su;Park, No-Cheol;Park, Young-Pil
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.1272-1275
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    • 2007
  • The HDD (hard disk drive) using Load/Unload (L/UL) technology includes the benefits which are increased areal density, reduced power consumption and improved shock resistance than those of contact-start-stop (CSS). Dynamic L/UL has been widely used in portable hard disk drive and will become the key technology for developing the small form factor hard disk drive. Main design objectives of the L/UL mechanisms are no slider-disk contact or no media damage even with contact during L/UL, and a smooth and short load and unload process. In this paper, we focus on state matrix, pitch static attitude (PSA), roll static attitude (RSA), loading/unloading contour (LC/ULC), impact force and contact. Stability of slider is mainly determined by PSA and RSA. State matrix by PSA and RSA is also important indicator. Therefore we analyze state matrix of SFF HDD suspension through the LC/ULC.

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A Study on the Impact of HVDC Transmission System to Interconnect Large-scale Power Generation Plants to Power Grid in Korea (HVDC 송전을 이용한 동해안 신규전원의 수도권 계통 연계방안에 대한 연구)

  • Han, Su-Young;Gwon, Do-Hun;Chung, Il-Yop;Lim, Jae-Bong
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.12
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    • pp.1647-1656
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    • 2013
  • Although the demand for electricity has been increasing these days, it becomes more difficult to find new sites for large-scale power generation plants near urban areas due to environmental and economic issues. Therefore, new power plants are forced off to rural or desolate coastal areas. As a result, there is significant regional imbalance in power generation and consumption between urban and rural areas in South Korea. This paper investigates the feasibility of high-voltage DC (HVDC) system as a candidate for electric power transmission system from east-coastal sites to metropolitan area. To this end, this paper analyzes transient stability and dynamic impact of a HVDC transmission system and compares the results to conventional high-voltage AC (HVAC) transmission systems via PSS/E simulation. This paper also examines the effect of HVDC system to voltage variation and low-frequency resonance in the neighboring buses in the grid using ESCR(Effective Short Circuit Ratio)과 UIF(Unit Interaction Factor) indices.

How Much does Job Autonomy Matter for Job Performance of Chinese Supervising Engineers: A Quantitative Study

  • CUI, Nan;XIAO, Shu-Feng
    • East Asian Journal of Business Economics (EAJBE)
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    • v.9 no.3
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    • pp.71-82
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    • 2021
  • Purpose - The purpose of this study is to examine the intermediary role of job satisfaction between job autonomy and job performance and whether the process was adjusted based on the work context. Research design, data, and methodology - This study was conducted by sample survey method on 334 supervising engineers. Data analysis methods were frequency analysis, confirmatory factor analysis, reliability analysis, correlation analysis, and structural equation model analysis. Result - The results of this study suggest that: (1) after controlling for age, position, and working years, job autonomy had a significant positive impact on job performance, (2) job autonomy can not only directly affect job performance but also indirectly affect performance through job satisfaction, (3) job satisfaction has an intermediary effect on job autonomy and job performance, and (4) the relationship between job autonomy and job satisfaction is moderated by the work context, and the result showed a negative moderating effect. Conclusion - This study suggests that job autonomy significantly improves job performance, and the higher job autonomy a supervising engineer has, the more satisfied they are with their work, thus enriching the precursor research on dynamic changes in job performance. When the working environment is poor, supervisors are more sensitive to the perception of job autonomy and have a stronger impact on job satisfaction and performance.

Effect of International Trade and Business for Approval Mediated by Relationship Capabilities on Korea's Export Growth

  • Bong-Ju Kang;Yang-Kee Lee
    • Journal of Korea Trade
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    • v.26 no.6
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    • pp.61-82
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    • 2022
  • Purpose - This study analyzed the effect of obtaining international products and qualification certification on exports according to the suitability evaluation system. Recently, non-tariff barriers have emerged as technical barriers, and the Biden administration is trying to achieve export growth and economic growth by utilizing the demand for conformity assessment following the Fourth Industrial Revolution and the free trade system from the perspective of Korea. Design/methodology - This study analyzed the effect of a manufacturer's product certification acquisition on a company's export performance using Resource-Based View-based multiple regression analysis. To this end, concentration validity was confirmed through Factor analysis and Cronbach's alpha, and correlation analysis was performed to verify discriminant validity. Findings - Product certification and qualification have a positive impact on the company's export performance. In particular, technological dynamism and relationship control have had a significant impact. Originality/value - Considering that the Conformity Assessment Management Act will take effect in earnest in 2022, this study is believed to suggest that companies that have been certified to meet international standards may improve their export performance and increase their value in the future. International market.

Impact Effects of Multi-Girder Steel Bridges Under Various Traffic Conditions (차량하중에 의한 다주형 강판형교의 충격계수 변화에 관한 연구)

  • 김상효;허진영
    • Computational Structural Engineering
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    • v.10 no.3
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    • pp.233-240
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    • 1997
  • The study presents the linear dynamic analysis of multi-girder steel bridges under vehicular movement to examine the performance characteristics due to the various structural and loading conditions. The road surface roughness and bridge-vehicle interactions are considered. The road surface profiles for the approaching roadway and bridge decks are generated from power spectral density functions for different road roughness conditions. A new filtering method using the wheel trace is proposed to obtain the more rational bridge-vehicle interactions from the randomly generated road surface. The possible settlement condition between the bridge deck and approaching roadway is also included. The dynamic responses of various bridges designed according to current design practice are examined, in which important structural parameters(such as span length, girder spacing, etc.) are considered systematically. In addition to the basic loading conditions due to a single truck passing on the bridge, the traffic conditions of multi-truck traveling either consecutively on the same lane or side-by-side on the adjacent lanes are also evaluated.

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Effects of Open or Closed Suctioning on Lung Dynamics and Hypoxemia in Mechanically Ventilated Patients (기관 내 흡인 유형이 인공호흡기 대상자의 폐기능과 저산소혈증에 미치는 효과)

  • Lee, Eun Young;Kim, Su Hyun
    • Journal of Korean Academy of Nursing
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    • v.44 no.2
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    • pp.149-158
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    • 2014
  • Purpose: This study was conducted to compare effects of open and closed suctioning methods on lung dynamics (dynamic compliance, tidal volume, and airway resistance) and hypoxemia (oxygen saturation and heart rate) in mechanically ventilated patients. Methods: This study was a cross-over repeated design. Participants were 21 adult patients being treated with endotracheal intubation using a pressure-controlled ventilator below Fraction of Inspired Oxygen ($FiO_2$) 60% and PEEP $8cmH_2O$. Data were collected at baseline and 1, 2, 3, 4, 5, and 10 minutes after suctioning. Data were analyzed using two-factor ANOVA with repeated measures on time and suctioning type. Results: Effects of the interaction between suction type and time were significant for oxygen saturation and heart rate but not significant for dynamic compliance, tidal volume, or airway resistance. Prior to performance of suctioning, tidal volume and oxygen saturation were significantly lower, but airway pressure and heart rate were significantly higher using the closed suctioning method as compared with the open suctioning method. Conclusion: For patients on ventilator therapy below $FiO_2$ 60% and PEEP $8cmH_2O$, open suctioning performed after delivery of 100% $FiO_2$ using a mechanical ventilator may not have as much negative impact on lung dynamics and hypoxemia as closed suctioning.

A Study on Dynamic Characteristics of Single Lap Joints with Different Joining Methods (체결방법에 따른 랩조인트의 동특성 해석)

  • Jung, Y.D.;Park, M.K.;Bahk, S.M.;Choi, Y.S.
    • Proceedings of the KSME Conference
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    • 2001.06b
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    • pp.624-629
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    • 2001
  • Two types of bolted lap joints, one with a viscoelastic layer and the other without the viscoelastic layer were chosen to analyze the dynamic characteristics of the joints with the mechanical properties of the bolts of the joints being taken as computational variables. The finite element method was used along with the impact hammer technique to verify the FEM model. The results in the bolted lap joints reveal that the higher the Young's Modulus for the bolts are the higher the natural frequencies results for the joints. However, the natural frequency differences in the first and second mode are not substantial but become noticeable in the higher modes. Lower natural frequencies were obtained for the bolted lap joints with the viscoelastic layer when compared with those of the bolted lap joints without the viscoelastic layer. And the differences in the natural frequencies for the two types of joints are relatively small in the first and second mode whereas in the higher mode the differences become significant. The loss factors were observed to be significant especially in the second mode for the bolted lap joints with the viscoelastic layer.

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Dynamic Behavior of External Post-tensioned Non-ballast Steel Plate Girder Railway Bridge (외부 후 긴장된 무도상 철도 판형교 동적 거동)

  • Park, Yong Gul;Park, Young Hoon;Choi, Dong Ho
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.3A
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    • pp.315-322
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    • 2008
  • The present study applied the external post tensioning reinforcement method for reinforcing a non-ballast steel plate girder railway bridge, and the effects of the strength of tendons and the level of post-tensioning force on the dynamic behavior are experimented and analyzed. According to the results of this study, the natural frequency was increased by the strength of tendons but it was decreased by the rise of post-tensioning force and as a consequence the introduction of post-tensioning force decreased natural frequency slightly. It was analyzed that further study is need to establish the exact relations between post-tensioning force and natural frequency. In addition, it was found that the dynamic displacement, dynamic bending stress and vertical acceleration were decreased by the external post-tensioning. On the other hand, external post-tensioning increased horizontal acceleration by up to 20%, which was around 70% of vertical acceleration. This needs further study.

Estimation about Local Strength using FE-Analysis for Steel Yacht (유한요소해석을 이용한 강선요트의 국부강도 평가)

  • Park Joo-Shin;Ko Jae-Yong
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.11 no.2 s.23
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    • pp.77-82
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    • 2005
  • Previously sailing yachts or leisure yachts were mainly made from FRP(Fiber glass reinforced plastic) in the small shipbuilding, but recently there is a trend to replace it for steel or aluminum to substitute FRP for environmental friendly materials. Although It have to need a many checked item in case of hull girder strength and transverse strength normally evaluate base on calculation of class guideline so called direct calculation method. Otherwise. this method of initial structural design considered enough for safety margin on the structure. But, case of small craft must consider for evaluating local strength through rational method. In this paper, check the bow structure members for satisfying results base on allowable stress criterion of damaged bow structure by dynamic load due to slamming and bottom impact load due to pitching motion through finite element analysis. and investigate engine bed structure considering engine weight load and transverse wave load.

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Experimental study on models of cylindrical steel tanks under mining tremors and moderate earthquakes

  • Burkacki, Daniel;Jankowski, Robert
    • Earthquakes and Structures
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    • v.17 no.2
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    • pp.175-189
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    • 2019
  • The aim of the study is to show the results of complex shaking table experimental investigation focused on the response of two models of cylindrical steel tanks under mining tremors and moderate earthquakes, including the aspects of diagnosis of structural damage. Firstly, the impact and the sweep-sine tests have been carried out, so as to determine the dynamic properties of models filled with different levels of liquid. Then, the models have been subjected to seismic and paraseismic excitations. Finally, one fully filled structure has been tested after introducing two different types of damages, so as to verify the method of damage diagnosis. The results of the impact and the sweep-sine tests show that filling the models with liquid leads to substantial reduction in natural frequencies, due to gradually increasing overall mass. Moreover, the results of sweep-sine tests clearly indicate that the increase in the liquid level results in significant increase in the damping structural ratio, which is the effect of damping properties of liquid due to its sloshing. The results of seismic and paraseismic tests indicate that filling the tank with liquid leads initially to considerable reduction in values of acceleration (damping effect of liquid sloshing); however, beyond a certain level of water filling, this regularity is inverted and acceleration values increase (effect of increasing total mass of the structure). Moreover, comparison of the responses under mining tremors and moderate earthquakes indicate that the power amplification factor of the mining tremors may be larger than the seismic power amplification factor. Finally, the results of damage diagnosis of fully filled steel tank model indicate that the forms of the Fourier spectra, together with the frequency and power spectral density values, can be directly related to the specific type of structural damage. They show a decrease in the natural frequencies for the model with unscrewed support bolts (global type of damage), while cutting the welds (local type of damage) has resulted in significant increase in values of the power spectral density for higher vibration modes.