• Title/Summary/Keyword: mode behavior

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Damage Detection of Shear Building Structures Using Dynamic Response (동적응답신호를 이용한 전단형 건물의 손상추정)

  • Yoo, Suk-Hyeong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.18 no.3
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    • pp.101-107
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    • 2014
  • Damage location and extent of structure could be detected by the inverse analysis on dynamic response properties such as frequencies and mode shapes. The dynamic response of building structures has many noise and affected by nonstructural members and, above all, the behavior of building structure is more complex than civil structure and this makes the damage detection difficult. In recent researches the damage is detected by the indirect index such as sensitivity or assumed values. However, for the more reasonable damage detection, it needs to use the damage index directly induced from dynamic equation. The purpose of this study is to provide the damage detection method on shear building structures by the damage index directly induced from dynamic equation. The provided damage index could be estimated from measured mode shape of undamaged structure and frequency difference between undamaged and damaged structure. The damage detection method is applied to numerical analysis model such as MATLAB and MIDAS GENw for the verification. The damage index at damaged story represents (-) sign and 15 times than other undamaged sories.

Effects of Electrostatic Discharge Stress on Current-Voltage and Reverse Recovery Time of Fast Power Diode

  • Bouangeune, Daoheung;Choi, Sang-Sik;Cho, Deok-Ho;Shim, Kyu-Hwan;Chang, Sung-Yong;Leem, See-Jong;Choi, Chel-Jong
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.14 no.4
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    • pp.495-502
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    • 2014
  • Fast recovery diodes (FRDs) were developed using the $p^{{+}{+}}/n^-/n^{{+}{+}}$ epitaxial layers grown by low temperature epitaxy technology. We investigated the effect of electrostatic discharge (ESD) stresses on their electrical and switching properties using current-voltage (I-V) and reverse recovery time analyses. The FRDs presented a high breakdown voltage, >450 V, and a low reverse leakage current, < $10^{-9}$ A. From the temperature dependence of thermal activation energy, the reverse leakage current was dominated by thermal generation-recombination and diffusion, respectively, at low and high temperature regions. By virtue of the abrupt junction and the Pt drive-in for the controlling of carrier lifetime, the soft reverse recovery behavior could be obtained along with a well-controlled reverse recovery time of 21.12 ns. The FRDs exhibited excellent ESD robustness with negligible degradations in the I-V and the reverse recovery characteristics up to ${\pm}5.5$ kV of HBM and ${\pm}3.5$ kV of IEC61000-4-2 shocks. Likewise, transmission line pulse (TLP) analysis reveals that the FRDs can handle the maximum peak pulse current, $I_{pp,max}$, up to 30 A in the forward mode and down to - 24 A in the reverse mode. The robust ESD property can improve the long term reliability of various power applications such as automobile and switching mode power supply.

Effect of Weldbond Process on the Weldability of 1.2GPa Grade Galvannealed TRIP Steel for Car Body Manufacturing (차체용 1.2GPa급 합금화아연도금 TRIP강의 용접성에 미치는 Weldbond 공정의 효과)

  • Lee, Jong-Dae;Lee, Hye-Rim;Kim, Mok-Soon;Seo, Jong-Deok;Kim, Jun-Ki
    • Journal of Welding and Joining
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    • v.34 no.6
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    • pp.28-34
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    • 2016
  • Galvannealed(GA) steels are now generally used in car body manufacturing for corrosion resistance. In this study, the weldability and joint mechanical behavior of a newly developed 1.2GPa grade GA ultra high strength TRIP(transformation induced plasticity) steel was investigated for three joining processes, such as adhesive bonding, resistance spot welding and weldbonding. Under both shear and peel stress conditions, the failure mode of the adhesive joints were the mixture of the adhesive cohesive failure, adhesive interface failure and coating layer failure. It means that the adhesion strength of GA coating onto the base metal was similar to that of adhesive bonding onto the GA coating. Under the shear stress condition, the weldbonding exerted to expand the optimal spot welding condition of 1.2GPa GA TRIP steel because the strength of adhesive bond overwhelmed that of the resistance spot weld. Under the peel stress condition, the weldbonding also exerted to expand the optimal spot welding condition of 1.2GPa GA TRIP steel by inducing the tear fracture mode rather than the partial plug fracture mode.

Light Coupling and Propagation Between a Fiber and a Dielectric Slab with a Conductor Cladding (측면 연마된 광섬유와 완전도체면 아래의 유전체 사이에서의 결합과 전파특성의 해석)

  • Kwon, Kwang-Hee;Yoon, Ki-Hong;Kim, Jeong-Hoon;Song, Jae-Won;Park, Euy-Dong;Son, Seok-Woo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.2A
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    • pp.70-79
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    • 2003
  • A theoretical presentation of evanescent coupling is offered with respect to the refractive indexes between a side polished optical fiber and an infinitely planar waveguide with a conductor cladding(PWGCC). The PWG is suspended at a constant distance from an unclad fiber core and attached with the perfect conductor(PEC) on one side. The behavior of the distributed coupler is examined using a coupled mode model, which takes account of the two dimensions of the waveguide configuration. The coupling and propagation of light were found to depend on both the relationship between the refractive index values of each structure and the configuration of the side polished fiber used in the PWGCC. The spreading of light in the unconfined direction of the PWGCC is described in terms of a simple geometrical interpretation of the synchromization condition that is in agreement with a previous investigation of the problem based on the coupled-mode theory(CMT). The power of the light propagation in the fiber decreased exponentially along the fiber axis as it was transferred to the PWGCC.

Analyzing the Characteristics of Trip Chaining Activities of the Elderly in Seoul Metropolitan Area (수도권 고령자의 통행사슬 특성에 관한 연구)

  • Lee, Hyangsook;Choo, Sangho;Kim, Jiyoon
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.13 no.2
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    • pp.68-79
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    • 2014
  • This paper analyzes the characteristics of trip chaining activities of elderly and explores temporal and spatial distribution. The research also estimates ordered probit model and binary logistic model to investigate various factors affecting trip chaining and mode choice patterns. We utilized household survey data for elderly conducted in 2006 and 2010 in Seoul metropolitan area. Research results indicate that trip chaining showed an increasing trend and simple trip chaining counts for more than 85%. GIS mapping expressed spatial distribution of trip departure and arrival areas, particularly showing regional changes in job-related trips. We also found that more factors influence trip chaining in 2010, compared with 2006, and travel cost is more sensitive than travel time in determining travel mode. The research contributes to establish transportation policies based on travel behavior of elderly in a upcoming super-aged society.

High Cyclic Fatigue Life and Fracture Behaviors of Shot-Peened Bearing Steel (쇼트피닝 처리를 한 베어링강의 고사이클 피로수명 및 파괴거동)

  • Yoon, Sang-Jae;Choi, Nak-Sam
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.9
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    • pp.1119-1129
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    • 2011
  • Shot-peening effects on the fatigue behavior of bearing steel were investigated under the high cyclic loading. Hourglass shape specimens were made of bearing steel(JIS-SUJ2) for rotary bending fatigue tests. Two kinds of treatments were performed : a heat treatment and a shot-peened surface treatment after the heat treatment. The fracture surfaces of specimens were classified into two types of fracture mode : the surface fracture mode induced by a surface defect and the internal fracture mode induced by a nonmetallic inclusion. Inclusion depth and shape affected considerably the fatigue life. Shot-peening treatment improved much the fatigue life of the bearing steel under low and high levels of cyclic loads. Probabilistic-stress-life (P-S-N) curves were suggested for the reliable fatigue life estimation of the improved bearing steel.

Analyzing a Differentiation of IT Governance Decision Structure: Application of IT Strategic Grid Framework (IT 거버넌스 의사결정 구조의 차이 분석: IT 전략 그리드 프레임워크 적용)

  • Lee, Bong-Gyou;Choi, Dong-Jin;Lee, Young-Hee;Oh, Ik-Jin
    • The KIPS Transactions:PartD
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    • v.15D no.2
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    • pp.285-296
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    • 2008
  • The purpose of this paper is to examine the IT governance decision structure of the four strategic modes of IT strategy grid, and compare and analyze the differences in the IT governance decision structure of companies that produce superior results and those that produce inferior results. The survey method was used for this paper, and data from a total of 209 companies that were listed on the KOSDAQ 300 and KOSPI 200 were used for the analysis. The results show that each mode has a different IT governance decision structure from the others, and the IT governance decision structure of companies with high results and those with low results are also different for each mode. The results of this paper are significant in that, for each mode, it presents the decision structure framework for promoting desirable behavior of companies carrying out IT governance.

An Analysis of Mechanism of Auto-Sensing Breaker's Automatic Impact (지능형 브레이커의 자동타격 메카니즘 분석)

  • Park, Sung-Su;Noh, Dae-Kyung;Lee, Dae-Hee;Lee, Geun-Ho;Kang, Young-Ky;Cho, Jae-Sang;Jang, Joo-sup
    • Journal of the Korea Society for Simulation
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    • v.25 no.4
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    • pp.31-42
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    • 2016
  • This study aims to identify the core technology for the automatic impact of the auto-sensing breaker that is one of the construction machinery which do not have a notable development success case yet in Korea. The study has been carried out as follows. Firstly, an analysis model was developed after determining the interconnection of pressure receiving area, opening area and port. And then, a simulation of situation that hard rock and soft rock are mixed was carried out to verify if it is possible to switch between long impact mode and short impact mode continuously. Lastly, the dynamic behavior of automatic control valve induced by the change of impact mode was analyzed based on the analysis result to decipher the core principle of automatic impact control.

Near-elliptic Core Triangular-lattice and Square-lattice PCFs: A Comparison of Birefringence, Cut-off and GVD Characteristics Towards Fiber Device Application

  • Maji, Partha Sona;Chaudhuri, Partha Roy
    • Journal of the Optical Society of Korea
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    • v.18 no.3
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    • pp.207-216
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    • 2014
  • In this work, we report detailed numerical analysis of the near-elliptic core index-guiding triangular-lattice and square-lattice photonic crystal fiber (PCFs); where we numerically characterize the birefringence, single mode, cut-off behavior and group velocity dispersion and effective area properties. By varying geometry and examining the modal field profile we find that for the same relative values of $d/{\Lambda}$, triangular-lattice PCFs show higher birefringence whereas the square-lattice PCFs show a wider range of single-mode operation. Square-lattice PCF was found to be endlessly single-mode for higher air-filling fraction ($d/{\Lambda}$). Dispersion comparison between the two structures reveal that we need smaller lengths of triangular-lattice PCF for dispersion compensation whereas PCFs with square-lattice with nearer relative dispersion slope (RDS) can better compensate the broadband dispersion. Square-lattice PCFs show zero dispersion wavelength (ZDW) red-shifted, making it preferable for mid-IR supercontinuum generation (SCG) with highly non-linear chalcogenide material. Square-lattice PCFs show higher dispersion slope that leads to compression of the broadband, thus accumulating more power in the pulse. On the other hand, triangular-lattice PCF with flat dispersion profile can generate broader SCG. Square-lattice PCF with low Group Velocity Dispersion (GVD) at the anomalous dispersion corresponds to higher dispersion length ($L_D$) and higher degree of solitonic interaction. The effective area of square-lattice PCF is always greater than its triangular-lattice counterpart making it better suited for high power applications. We have also performed a comparison of the dispersion properties of between the symmetric-core and asymmetric-core triangular-lattice PCF. While we need smaller length of symmetric-core PCF for dispersion compensation, broadband dispersion compensation can be performed with asymmetric-core PCF. Mid-Infrared (IR) SCG can be better performed with asymmetric core PCF with compressed and high power pulse, while wider range of SCG can be performed with symmetric core PCF. Thus, this study will be extremely useful for designing/realizing fiber towards a custom application around these characteristics.

Effect of curing conditions on mode-II debonding between FRP and concrete: A prediction model

  • Jiao, Pengcheng;Soleimani, Sepehr;Xu, Quan;Cai, Lulu;Wang, Yuanhong
    • Computers and Concrete
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    • v.20 no.6
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    • pp.635-643
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    • 2017
  • The rehabilitation and strengthening of concrete structures using Fiber-Reinforced Polymer (FRP) materials have been widely investigated. As a priority issue, however, the effect of curing conditions on the bonding behavior between FRP and concrete structures is still elusive. This study aims at developing a prediction model to accurately capture the mode-II interfacial debonding between FRP strips and concrete under different curing conditions. Single shear debonding experiments were conducted on FRP-concrete samples with respect to different curing time t and temperatures T. The J-integral formulation and constrained least square minimization are carried out to calibrate the parameters, i.e., the maximum slip $\bar{s}$ and stretch factor n. The prediction model is developed based on the cohesive model and Arrhenius relationship. The experimental data are then analyzed using the proposed model to predict the debonding between FRP and concrete, i.e., the interfacial shear stress-slip relationship. A Finite Element (FE) model is developed to validate the theoretical predictions. Satisfactory agreements are obtained. The prediction model can be used to accurately capture the bonding performance of FRP-concrete structures.