• Journal of information and communication convergence engineering
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• v.12 no.2
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• pp.75-82
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• 2014

Dispersion management (DM), optical phase conjugation (OPC), and the combination of DM and OPC are promising techniques to compensate for optical signal distortion due to group velocity dispersion and nonlinear Kerr effects. The system performance improvement in DM links combined with OPC has been reported; however, the fixed residual dispersion per span (RDPS) usually used in these links restricts the flexibility of link configuration. Thus, in this paper, a flexible optical link configuration with artificially distributed single-mode fiber (SMF) lengths and RDPS in the combination of DM and OPC is proposed. Simulation results show that the best artificial distribution pattern is the gradually descending distribution of SMF lengths and the gradually ascending distribution of RDPS, as the number of fiber spans is increased, regardless of the average RDPS, the optimal net residual dispersion, and the dispersion coefficient of the dispersion compensating fiber.

• Journal of Advanced Navigation Technology
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• v.16 no.5
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• pp.801-809
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• 2012

Dispersion management (DM) is the typical technique compensating for the distorted signals due to interaction of group velocity dispersion (GVD) and optical nonlinear effects for transmitting wavelength division multiplexed (WDM) channel with the excellent performance. Optimal net residual dispersion (NRD) and effective launching power range of optical transmission links with random distribution and artificial distribution of single mode fiber (SMF) length and residual dispersion per span (RDPS) required to flexibly design of optical links in DM. It is confirmed that optimal net residual dispersion (NRD) are +10 ps/nm and -10 ps/nm controlled by precompensation and postcompensation, respectively, in both of the considered distribution patterns of SMF length and RDPS. And, in optimal NRD, system performance in optical links with the descending distribution of SMF length and the ascending distribution of RDPS among the artificial distribution patterns are more improved, consequently, effective launching power range is expanded by almost 2 dB than those in optical links with the uniform distribution.

• Journal of the Korean Data and Information Science Society
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• v.7 no.1
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• pp.119-127
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• 1996

The concepy of positive aging describles the adverse effects of age on the lifetime of units. Various aspects of this concepts are described in terms of conditional probability distribution of residual life times, failure rates, equilibrium distributions, etc. In this paper we will consider some partial ordering relations of life distribution under residual life functions and equilibrium distributions.

• Journal of the Korean Society of Safety
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• v.8 no.2
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• pp.64-71
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• 1993

In this study, the purpose is to investigate the influence of initial residual stresses on the fatigue crack growth behaviors after the distribution of initial residual stresses Is measured when the crack is growing from the compressive residual stresses field to the tensile residual stress field. Also, the Influence of the variation of residual stress distribution on the fatigue crack growth behaviors at the crack tip is studied when the initial crack li applied on base metal, weld metal and HAZ respectively.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.1
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• pp.101-112
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• 1994

The measurement of residual stress distribution of $Si_3N_4/SUS304$ joint was performed on 23 specimens with the same joint condition using PSPC type X-ray stress measurement system and the two-dimensional elastoplastic analysis using finite element method was also attempted. As results, residual stress distribution near the interface on the ceramic side of the joint was revealed quantitatively. Residual stress on the ceramic side of the joint was turned out to be tensional near the interface, maximum along the edge, varying in accordance with the condition of the joint and variance to be most conspicuous for the residual stress normal to the interface characterized by the stress singularities. In the vicinity of the interface, the high stress concentration occurs and residual stress distributes three-dimensionally. Therefore, the measured stress distribution differed remarkably from the result of the two-dimensional finite-element analysis. Especially at the center of the specimen near the interface, the residual stress, $\sigma_{x}$ obtained from the finite element analysis was compressive, whereas measurement using X-ray yielded tensile $\sigma_{x}$. Here we discuss two dimensional superposition model the discrepancy between the results from the two dimensional finite element analysis and X-ray measurement.

• Proceedings of the Optical Society of Korea Conference
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• 2005.07a
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• pp.206-207
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• 2005

The gradient of the residual stress distribution in the mechanical defect on the optical fiber surface was investigated. This gradient of the residual stress distribution appeared in both of the core and the clad of the mechanical defect region on the optical fiber. The residual stress measurement was suggested as a investigation method of the mechanical defect on the optical fiber.

• Journal of the korean Society of Automotive Engineers
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• v.13 no.6
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• pp.109-118
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• 1991

In this study, it is intended to investigate the effect of the grinding conditions such as table feed, down feed, cross feed of residual stress distribution. And this distribution is investigated upon the grinding direction and the its orthogonal direction at ground layers. The material is used carbon steel (SM20C) which usually used to motor axis. And in order to be considered as Bernoulli-Euler beam, the dimension of the specimen is appropriately designed. According as corroiding the ground surface, the residual stress layers are removed and strain which occured on account of unbalance of internal stress is detected by rosette-gate. Through A/D converter and computer, these values are saved and evaluated residual stress by stress-strain relation formula. Finally, these results are diagrammatized with Auto Cad. The results obtained are as follows. As the depth from the ground surface increases in grinding direction and its orthogonal direction, tensile residual stress exists in the surface, and subsequently it becomes compressive residual stress as it goes downward. As the table feed, the cross feed and the down feed increase, maximum residual stress is transformed form the tensile to the compressive.

• Korea-Australia Rheology Journal
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• v.19 no.4
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• pp.183-190
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• 2007

Injection molding is one of the most common operations in polymer processing. Good quality products are usually obtained and major post-processing treatment is not required. However, residual stresses which exist in plastic parts affect the final shape and mechanical properties after ejection. Residual stresses are caused by polymer melt flow, pressure distribution, non-uniform temperature field, and density distribution. Residual stresses are predicted in this study by numerical methods using commercially available softwares, $Hypermesh^{TM},\;Moldflow^{TM}\;and\;ABAQUS^{TM}$. Cavity filling, packing, and cooling stages are simulated to predict residual stress field right after ejection by assuming an isotropic elastic solid. Thermo-viscoelastic stress analysis is carried out to predict deformation and residual stress distribution after annealing of the part. Residual stresses are measured by the hole drilling method because the automotive part selected in this study has a complex shape. Residual stress distribution predicted by the thermal stress analysis is compared with the measurement results obtained by the hole drilling method. The molded specimen has residual stress distribution in tension, compression, and tension from the surface to the center of the part. Viscoelastic deformation of the part is predicted during annealing and the deformed geometry is compared with that measured by a three dimensional scanner. The viscoelastic stress analysis with a thermal cycle will enable us to predict long term behavior of the injection molded polymeric parts.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.650-652
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• 2011

Condition of random distribution of residual dispersion per span (RDPS) for transmission of 40 Gbps optical signal with good performance through optical transmission links with dispersion management (DM) of random RDPS distribution and optical phase conjugator (OPC) is induced in this paper.

• Fibers and Polymers
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• v.2 no.4
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• pp.203-211
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• 2001

Residual stresses were predicted by a flow analysis in the mold cavity and residual stress distribution in the injection molded product was measured. Flow field was analyzed by the hybrid FEM/FDM method, using the Hele Shaw approximation. The Modified Cross model was used to determine the dependence of the viscosity on the temperature and the shear rate. The specific volume of the polymer melt which varies with the pressure and temperature fields was calculated by the Tait\`s state equation. Flow analysis results such as pressure, temperature, and the location of the liquid-solid interface were used as the input of the stress analysis. In order to calculate more accurate gap-wise temperature field, a coordinate transformation technique was used. The residual stress distribution in the gap-wise temperature field, a coordinate transformation technique was used. The residual stress distribution in the gap-wise direction was predicted in two cases, the free quenching, under the assumption that the shrinkage of the injection molded product occurs within the mold cavity and that the solid polymer is elastic. Effects of the initial flow rate, packing pressure, and mold temperature on the residual stress distribution was discussed. Experimental results were also obtained by the layer removal method for molded polypropylene.