• Title/Summary/Keyword: fundamental parameters

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Control Algorithm of Thyristor Rectifier to Improve Arc Stability in DC Arc Furnace

  • Jung, Kyungsub;Suh, Yongsug;Kim, Taewon;Park, Taejun
    • Proceedings of the KIPE Conference
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    • 2012.07a
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    • pp.371-372
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    • 2012
  • In this paper fundamental features of the arc stability in DC arc furnace of 720V/100kA/72MW have been investigated. Cassie-Mayr arc model has been employed for the target dc arc furnace. In order to characterize the parameters of Cassie-Mayr arc model and the behavior of unstable arc dynamics, the advanced arc simulations of magneto-hydrodynamics (MHD) has been performed. Based on the results of MHD simulation, dc arc dynamic resistance is proposed to be an effective arc stability function reflecting the instability of dynamic arc behavior. The experimental result confirms the usefulness of proposed dynamic arc resistance as arc stability function. The proposed arc stability function can be regarded as an effective criterion for the overall power conversion system to maintain highly stable arcing operation leading to better productivity and reliability.

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Dynamic behavior and impact analysis of high level impact system (고 충격 시스템의 충격력 및 동적 거동 해석)

  • 박춘식;박영필;양현석;김효준;최의중;이성배
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.11b
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    • pp.597-602
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    • 2001
  • The structure of the human body has a limit to absorb the high-level-impact that occurs in shoulder-fired system. In other to solve this problem, short recoil system is applied to shoulder-fired system, and is verified experimentally, and then is performed analysis of parameters sensitivity, optimization of main part. According to the results, we developed A fundamental basis for buffering structure modeling that is operated by high level input in shoulder-fired system

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Dynamic Analysis of a System Using Reduced Modeling of Substructures (부분구조물의 단순모델화를 이용한 시스템의 동적해석)

  • Hwang, Woo-Seok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.2
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    • pp.200-207
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    • 2009
  • Complex systems are made of many subsystems, those are developed and manufactured by many part companies. Even though the information for a part is necessary to analyze the performance of the other part, it is not so easy to get the information for that part from other companies due to many reasons like security or compatibilities. If the modal parameters of a system between the connecting points are available, we can reconstruct a reduced model for that system in a physical coordinate not in a generalized coordinate. The assemble of the equations of motion for the main system and the reduced equations of motion for the connected system can give a response of the main system considering the effects of connected systems. The results show that the proposed method can give the response of a system accurately. The rule for the selection of modes is to use the fundamental modes whose natural frequencies are low.

Performance Simulation of a Ramjet Using Visual C++ Program

  • Owino, George Omollo;Kong, Chang-Duk
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.03a
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    • pp.499-502
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    • 2008
  • This paper presents on research findings of how Visual C++ program can be used to generate codes capable of performing ramjet engine simulation To understand the diversity and applicability of this tool an arbitrary ramjet model will be considered for which generated output values will be compared with those from a commercial program GASTURB 9 iterated under the same input parameters. Several governing thermodynamic equations will first be discussed in order that we understand the fundamental idea behind values printed out on the GUI. C++ compiler was chosen as a tool of use due to its availability, ease of use, ability to compute functions faster and uniquely possible to make a stand alone GUI executable in DOS mode. The program is developed in such a way that given the ambient flight conditions, burner exit temperature and several geometry areas the program generates its own input values used in the succeeding stations. A close resemblance of output values that define performance and thermodynamic state of the engine was realized between GASTURB 9 and using this code made from C++ compiler.

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Analytical Investigation on Fundamental Electrical Characteristics of Large Air-gap Superconducting Synchronous Machine

  • Yazdanian, M.;Elhaminia, P.;Zolghadri, M.R.;Fardmanesh, M.
    • Journal of Magnetics
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    • v.18 no.3
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    • pp.260-267
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    • 2013
  • In this paper a general 2-D model of a large air-gap synchronous machine either with non-magnetic or magnetic core rotor is investigated and electrical characteristics of the machine are analytically calculated. Considering the general model, analytical equations for magnetic field density in different regions of the large air-gap machine are calculated. In addition, self and mutual inductances in the proposed model of the machine have been developed, which are the most important parameters in the electromagnetic design and transient analysis of synchronous machines. Finite element simulation has also been performed to verify the obtained results from the equations. Analytical results show good agreement with FEM results.

Optimal design of truss structures using a new optimization algorithm based on global sensitivity analysis

  • Kaveh, A.;Mahdavi, V.R.
    • Structural Engineering and Mechanics
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    • v.60 no.6
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    • pp.1093-1117
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    • 2016
  • Global sensitivity analysis (GSA) has been widely used to investigate the sensitivity of the model output with respect to its input parameters. In this paper a new single-solution search optimization algorithm is developed based on the GSA, and applied to the size optimization of truss structures. In this method the search space of the optimization is determined using the sensitivity indicator of variables. Unlike the common meta-heuristic algorithms, where all the variables are simultaneously changed in the optimization process, in this approach the sensitive variables of solution are iteratively changed more rapidly than the less sensitive ones in the search space. Comparisons of the present results with those of some previous population-based meta-heuristic algorithms demonstrate its capability, especially for decreasing the number of fitness functions evaluations, in solving the presented benchmark problems.

Pose Tracking of Moving Sensor using Monocular Camera and IMU Sensor

  • Jung, Sukwoo;Park, Seho;Lee, KyungTaek
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.15 no.8
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    • pp.3011-3024
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    • 2021
  • Pose estimation of the sensor is important issue in many applications such as robotics, navigation, tracking, and Augmented Reality. This paper proposes visual-inertial integration system appropriate for dynamically moving condition of the sensor. The orientation estimated from Inertial Measurement Unit (IMU) sensor is used to calculate the essential matrix based on the intrinsic parameters of the camera. Using the epipolar geometry, the outliers of the feature point matching are eliminated in the image sequences. The pose of the sensor can be obtained from the feature point matching. The use of IMU sensor can help initially eliminate erroneous point matches in the image of dynamic scene. After the outliers are removed from the feature points, these selected feature points matching relations are used to calculate the precise fundamental matrix. Finally, with the feature point matching relation, the pose of the sensor is estimated. The proposed procedure was implemented and tested, comparing with the existing methods. Experimental results have shown the effectiveness of the technique proposed in this paper.

Acoustic characteristics of the sustained vowel phonation according to age groups (모음 연장 발성이 보이는 연령대별 음향음성학적 특성 연구)

  • Seo, Yoon-Jeong;Shin, Jiyoung
    • Phonetics and Speech Sciences
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    • v.10 no.4
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    • pp.67-76
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    • 2018
  • This study was performed to investigate acoustic characteristics of sustained vowels produced by Seoul Korean speakers. For this study, three hundred nine healthy adults were chosen as participants from Korean Standard Speech Database. These subjects were divided into five chronological age groups (20s, 30s, 40s, 50s, 60-70s) and two gender groups (male and female). Fundamental frequency (f0), jitter, shimmer, and NHR (noise-to-harmonics ratio) was measured with 8 Korean vowels (/ɑ/, /æ/, /ʌ/, /e/, /o/, /u/, /ɯ/, /i/) by using Praat. The results showed that the vowel type significantly affected all acoustic parameters. Gender affected f0, jitter, and NHR significantly. The mean female speakers' f0 was greater than the males', and the mean jitter and NHR of male speakers was greater than the females'. Moreover, age affected shimmer and NHR significantly; in particular, the shimmer and NHR of elderly speakers was greater than the young speakers.

In-situ fatigue monitoring procedure using nonlinear ultrasonic surface waves considering the nonlinear effects in the measurement system

  • Dib, Gerges;Roy, Surajit;Ramuhalli, Pradeep;Chai, Jangbom
    • Nuclear Engineering and Technology
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    • v.51 no.3
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    • pp.867-876
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    • 2019
  • Second harmonic generation using nonlinear ultrasonic waves have been shown to be an early indicator of possible fatigue damage in nuclear power plant components. This technique relies on measuring amplitudes, making it highly susceptible to variations in transducer coupling and instrumentation. This paper proposes an experimental procedure for in-situ surface wave nonlinear ultrasound measurements on specimen with permanently mounted transducers under high cycle fatigue loading without interrupting the experiment. It allows continuous monitoring and minimizes variation due to transducer coupling. Moreover, relations describing the effects of the measurement system nonlinearity including the effects of the material transfer function on the measured nonlinearity parameter are derived. An in-situ high cycle fatigue test was conducted using two 304 stainless steel specimens with two different excitation frequencies. A comprehensive analysis of the nonlinear sources, which result in variations in the measured nonlinearity parameters, was performed and the effects of the system nonlinearities are explained and identified. In both specimens, monotonic trend was observed in nonlinear parameter when the value of fundamental amplitude was not changing.

Compact, Wavelength-selectable, Energy-ratio Variable Nd:YAG Laser at Mid-ultraviolet for Chemical Warfare Agent Detection

  • Kim, Jae-Ihn;Cho, Ki Ho;Lee, Jae-Hwan;Ha, Yeon-Chul
    • Current Optics and Photonics
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    • v.3 no.3
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    • pp.243-247
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    • 2019
  • We have developed a compact, wavelength-selectable, Q-switched Nd:YAG laser at mid ultraviolet for chemical warfare agent detection. The fundamental wave at 1064 nm is delivered by a pulsed solid state laser incorporating with a square-type Nd:YAG rod in a resonator closed by two crossed Porro prisms for environmental reliability. The output energy at 213 nm ($5{\omega}$) and 266 nm ($4{\omega}$) by ${\chi}^{(2)}$ process in the sequentially disposed BBO crystals are measured to be 6.8 mJ and 15.1 mJ, respectively. The output wavelength is selected for $5{\omega}$ and $4{\omega}$ by a motorized wavelength switch. The energy ratio of the $5{\omega}$ to the $4{\omega}$ is varied from 0.05 to 0.85 by controlling the phase matching temperature of the nonlinear crystal for sum-frequency generation without change of the output pulse parameters.