• Journal of Advanced Navigation Technology
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• v.15 no.2
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• pp.248-255
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• 2011

An investigation has been carried out, by computer simulation, to evaluate the impact of dispersion compensation configurations on 960 Gbps wavelength division multiplexed (WDM) system with optical phase conjugator (OPC). The considered dispersion compensation configurations in this research are conventional one-end type and bi-end type. One-end and bi-end type are made by using one dispersion compensating fiber (DCF) and two DCFs to decrease dispersion accumulated in one single mode fiber (SMF) span, respectively. It is found that bi-end compensation configuration offers the equal performance with that of one-end configuration in WDM system with residual dispersion per span (RDPS) of 400 ps/nm if net residual dispersion (NRD) had to be optimized in each cases.

• Journal of the Korean Society of Systems Engineering
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• v.15 no.2
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• pp.108-115
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• 2019

The activities of managing and controlling the configuration of a system component over its life cycle are critical tasks in developing a high safety system as well as general system development. These configuration management activities should be defined through the management plan at the beginning of the life cycle, and should be performed continuously and systematically until the end of the project after the system or product development is completed. In this study, the configuration management process applied in the development of high safety railway signaling system was introduced and an efficient application proposals of it was proposed. In particular, configuration management through the establishment of a configuration management system based on computer tools is one of the important activities of maintaining the configuration integrity of the system or product.

• Journal of Photoscience
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• v.2 no.2
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• pp.99-101
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• 1995

A semiempirical methods(PM3-CI-UHF, MM2) for the evaluation of ground and excited state electronic structures of electron-donating substituents are applied to 4, 5', 8-trimethylpsoralen(TMP) with TMP dimer. Three types of product have been proposed; (1) pyrone< >pyrone, (2) pyrone< >furan, (3) hetero dimer resulting from the C$_4$-cycloaddition between the furan end of one TMP moiety and the pyrone end of the other, with cis-syn configuration.

• Journal of Communications and Networks
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• v.10 no.3
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• pp.351-361
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• 2008

This paper presents a delay-margin based traffic engineering (TE) approach to provide end-to-end quality of service (QoS) in multi-protocol label switching (MPLS) networks using differentiated services (DiffServ) at the link level. The TE, including delay, class, and route assignments, is formulated as a nonlinear optimization problem reflecting the inter-class and inter-link dependency introduced by DiffServ and end-to-end QoS requirements. Three algorithms are used to provide a solution to the problem: The first two, centralized offline route configuration and link-class delay assignment, operate in the convex areas of the feasible region to consecutively reduce the objective function using a per-link per-class decomposition of the objective function gradient. The third one is a heuristic that promotes/demotes connections at different links in order to deal with concave areas that may be produced by a trunk route usage of more than one class on a given link. Approximations of the three algorithms suitable for on-line distributed TE operation are also derived. Simulation is used to show that proposed approach can increase the number of users while maintaining end-to-end QoS requirements.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1045-1049
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• 2005

In this paper, the dynamic crawling of a five-bar planar mechanism is investigated. One complete cycle of the crawling selected in this study consists of four different steps, i) sliding at one contact point between the mechanism and the ground, ii) changing its configuration without sliding at two contact points, iii) sliding at the other contact point, and iv) again changing its configuration without sliding at two contact points. In this type of crawling, the crawling mechanism maintains the shape of the parallel structure throughout a complete crawling cycle. The modeling algorithm for serial manipulators proposed by M. Thomas and et al.[1] is employed by introducing imaginary joints and links which represent the contact interfaces between the one end of the mechanism and the ground, while the other end of the mechanism is regarded as an end-effector of the imaginary serial manipulator which treats the reaction force and torque at the contact point as external forces. Then, a complete cycle of dynamic crawling of the mechanism is investigated through various computer simulations. The simulation result show that the stable crawling characteristics of the mechanism could be secured when the proper configurations depending on specified frictional constraints are met.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1059-1062
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• 1995

In cutting system, relative displacement between rool and workpiece is very important. Even though there have been so many works for modeling cutting process of end-milling, most of them have considered only one displacement of either tool or workpiece instead of both. In this paper, the relative displacement between tool and workpiece is considered for modeling cutting process of end-milling using simple experimental modal analysis and cutting force simulation program is developed. In cutting force model, instantaneous uncut chip thickness model is used and Runge-Kutta method is used for the simulation of time varying cutting system.

• Steel and Composite Structures
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• v.29 no.3
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• pp.391-404
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• 2018

Researchers have been long studying new building implementation methods to improve the quality of construction, reduce the time of assembly, and increase productivity. One of these methods is the use of modular pre-fabricated structural forms that are composed of a beam, column, short column, pyramidal end block, and connection plates. In this study, a new geometry for the pyramidal end block was proposed that helps facilitate the assembly procedure. Since the proposed configuration affects the performance of this form of connection, its behavior was evaluated using finite element method. For this purpose, the connection was modeled in ABAQUS and then validated by comparing the outputs with experimental results. The research proceeded through analyzing 16 specimens under monotonic and cyclic loading. The results indicated that using the pyramidal end block not only makes the assembly process easier but also reduces the out-of-plane displacement of the short column webs and the vertical displacement of beam end. By choosing appropriate section properties for column and beam, the connection can bear a rotation up to 0.01 radians within its inelastic region and a total of 0.04 radians without any significant reduction in its bearing capacity.

• Journal of Environmental Science International
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• v.19 no.10
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• pp.1219-1227
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• 2010

In this study, the sensitivity analysis of bed changes due to the various sediment transport equations have been conducted for 80 km reach of the Lower Nakdong River using the HEC-6 which is one dimensional numerical model. The bed elevation changes according to the different sediment transport formulas were compared and analyzed quantitatively. As a result of the numerical simulation, the final bed elevation calculated by Engelund and Hansen(1967), Ackers and White(1973), and Yang(1979) formulas was similar to one another in configuration. The bed change simulated by Engelund and Hansen(1967) were greatest among them, for example, 5.5 m deposition and 2.9 m erosion for 100 years. Also, in the case of Toffaleti (1969) equation, the maximum bed deposition of 8.04 m after 100 years was induced at the 73 km location upstream of the Nakdong River Estuary Barrage. Meyer-Peter-M$\ddot{u}$ller(1948) and Wilcock(2001) formulas produced the deposition only at the upstream end and there was little bed change in the downstream area. The unreal bed configuration of continuously up and down pattern was simulated by Laursen(1958) transport equation.

• Journal of electromagnetic engineering and science
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• v.16 no.4
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• pp.241-247
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• 2016

This paper proposes the design and measurement of a 6-18 GHz front-end receiver module that has been combined into a one- channel output from a two-channel input for electronic warfare support measures (ESM) applications. This module includes a limiter, high-pass filter (HPF), power combiner, equalizer and amplifier. This paper focuses on the design aspects of reducing the noise figure (NF) and matching the phase and amplitude. The NF, linear equalizer, power divider, and HPF were considered in the design. A broadband receiver based on a combined configuration used to obtain low NF. We verify that our receiver module improves the noise figure by as much as 0.78 dB over measured data with a maximum of 5.54 dB over a 6-18 GHz bandwidth; the difference value of phase matching is within $7^{\circ}$ between ports.

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.125-130
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• 1994

A new cavity configuration for passive mode locking of fiber laser is proposed and demonstrated. It consists of a dichroic mirror at one end of the cavity, and a nonlinear loop mirror, which is a Sagnac loop, at the other end. The experimental observations are described for both Er-doped fiber laser and Nd-doped fiber laser. laser.