• Title/Summary/Keyword: Grid test

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A study on sub-nanosecoand pulser characteristic of electron gun (서브 나노초의 전자총 펄서 특성에 관한 연구)

  • Son, Y.G.;Jang, S.D.;Oh, J.S.
    • Proceedings of the KIEE Conference
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    • 2003.07c
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    • pp.1662-1664
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    • 2003
  • An electron gun system for a nanosecond pulse linac has been built and tested. The gun grid is driven with a grid pulser, which consists of an avalanche transistor pulser and parallel triode amplifier. The amplifier is installed in an end hole of the electron gun and provided for power amplification and polarity change of the output pulses of the avalanche transistor pulser. An output pulse of 200 V and 2 ns FWHM was obtained by using the grid pulser of can type transistors. Measurements with a test bench show that the electron gun can deliver 2ns pulse with with currents larger than 3A.

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Neutral Point Balancing Algorithm for Multi-level Converter under Unbalanced Operating Conditions

  • Jung, Kyungsub;Suh, Yongsug
    • Proceedings of the KIPE Conference
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    • 2015.07a
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    • pp.177-178
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    • 2015
  • This paper presents a neutral point deviation compensating control algorithm applied to a 3-level NPC converter. The neutral point deviation is analyzed with a focus on the current flowing out of or into the neutral point of the dc link. Based on the zero sequence components of the reference voltages, this paper analyzes the neutral point deviation and balancing control for 3-level NPC converter. An analytical method is proposed to calculate the injected zero sequence voltage for NP balancing based on average neutral current. This paper also proposes a control scheme compensating for the neutral point deviation under generalized unbalanced grid operating conditions. The positive and negative sequence components of the pole voltages and ac input currents are employed to accurately explain the behavior of 3-level NPC converter. Simulation and experimental results for a test set up of 30kW are shown to verify the validity of the proposed algorithm.

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Development of a Surface-Strain Measurement System Using the Image Processing Technique (화상처리법을 이용한 곡면변형률 측정 시스템의 개발)

  • 한상준;김영수;김형종;오수익
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1998.06a
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    • pp.171-182
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    • 1998
  • An automated surface-strain measuring system using the image processing technique is developed in the present study, which consists of the hardware to capture and to display digital images, and the software to calculate the 3D informations of grid points from two views. New or improved algorithms the mapping and establishing correspondence of grid points and elements, the camera calibration, and the subpixel measurement of grid points, are implemented. As an application of the present system the surface-strains of deformed blanks in the limitting dome height test, the square cup deep-drawing and punch stretching to obtain the forming limit diagram are measured. The results are compared with those obtained by conventional manual methods.

Development of a Surface-Strain Measurement System Using the Image Processing Technique (화상처리법을 이용한 곡면변형률 측정 시스템의 개발)

  • Han, Sang-Jun;Kim, Yeong-Su;Kim, Hyeong-Jong;O, Su-Ik
    • Transactions of Materials Processing
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    • v.7 no.6
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    • pp.575-585
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    • 1998
  • An automated surface-strain measuring system using the image processing technique is developed in the present study which consists of the hardware to capture and to display digital images. and the software to calculate the 3-D informations of grid points from two views. New or improved algorithms for the mapping and establishing correspondence of grid points and elements the camera calibration and the subpixel measurement of grid points are implemented. As an application of the present system the surface-strains of deformed blanks in the limitting dome height test the square cup deep-drawing and punch stretching to obtain the forming limit diagram are measured. The results are com-pared with those obtained by conventional manual methods.

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A Study on the Fault Process and Equipment Analysis of Plastic Ball Grid Array Manufacturing Using Data-Mining Techniques

  • Sim, Hyun Sik
    • Journal of Information Processing Systems
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    • v.16 no.6
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    • pp.1271-1280
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    • 2020
  • The yield and quality of a micromanufacturing process are important management factors. In real-world situations, it is difficult to achieve a high yield from a manufacturing process because the products are produced through multiple nanoscale manufacturing processes. Therefore, it is necessary to identify the processes and equipment that lead to low yields. This paper proposes an analytical method to identify the processes and equipment that cause a defect in the plastic ball grid array (PBGA) during the manufacturing process using logistic regression and stepwise variable selection. The proposed method was tested with the lot trace records of a real work site. The records included the sequence of equipment that the lot had passed through and the number of faults of each type in the lot. We demonstrated that the test results reflect the real situation in a PBGA manufacturing process, and the major equipment parameters were then controlled to confirm the improvement in yield; the yield improved by approximately 20%.

Independence and Homogeneity Tests of the Annual Maxima Data used to Estimate the Design Wave Height (설계파고 추정에 사용한 연 최대 자료의 독립 및 분포 동질 검정)

  • Cho, Hong Yeon;Jeong, Weon Mu;Back, Jong Dai
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.32 no.1
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    • pp.26-38
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    • 2020
  • A statistical test was carried out on the IID (Independently and Identically Distributed) assumption of the AM (Annual Maxima) data used to estimate the design wave height. The test was divided into independence (randomness) test and homogeneity test, and each test was conducted on AM data of 210 and 310 stations in coastal and inner coastal grids in typhoon and non-typhoon (monsoon) conditions. As a result of the independence test, the rejection ratios of the test are in the range of 1.8~5.3% and 1.4~6.0% for the non-typhoon and typhoon data sets, respectively. On the other hand, in the distribution difference test of typhoon data and nontyphoon data, the same distribution hypothesis was found to be rejected in the range of 47~79% according to the test method for both coastal grid and inner coastal grid. Therefore, in estimating design wave height by extreme value analysis, the estimation process by dividing the typhoon and non-typhoon data is appropriate.

Grid Dependency and Aerodynamic Analysis for Transonic Flow of Delta Wing using CFD (천음속영역의 삼각날개 격자의존성 및 공력해석)

  • Jeong, Kiyeon;Jung, Eunhee;Kang, Dong-Gi;Lee, Daeyeon;Kim, Dukhyun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.46 no.6
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    • pp.445-451
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    • 2018
  • This paper describes on introduction of CASE 4(Delta Wing) for EFD-CFD comparison workshop which is in charged of aerodynamic subcommittee of The Korean Society for Aeronautical and Space Science. The wind tunnel test will be performed later, angle of attack is set -5~20deg and mach number is set 0.7, 0.85, 1.2 to solve the transonic flow. The simulation test of grid dependency is conducted to determine the proper grid size of delta wing analysis. The tendency of lift and drag coefficient is determined according to the change of angle of attack based on the selected grid size.

The Field Applicability of Road Pavement Layer with Grid Typed Reinforcement and Dispersive Fiber (그리드형 보강재와 분산성 섬유를 활용한 도로 포장층의 현장 적용 특성)

  • Park, Ju-Won;Kim, Hun-Kyum;Kim, Sung-Bo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.3
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    • pp.53-59
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    • 2018
  • This study analyzed the field applicability through the combination of environment-friendly grid-typed reinforcements and pre-mixed fiber with filler. The film of the grid-typed reinforcement is made by recycled PE resin. And, Ascon fiber is obtained the dispersion by pre-mixing of filler. To be able to recognize in advance the various circumstances that could arise in the construction of the road pavement layer, we conducted a basic field application test of the (Mock Up) pavement layer. As a result, it was found that the pavement with environment-friendly grid-typed reinforcement and dispersive fiber construction had improved strength, stress, and rutting resistance. It is consistent with the strength and stress results of the actual test of the mock up specimen. It is expected to perform an effective role in the safety as well as the use of environment-friendly fibers in actual construction.

Leakage detection and management in water distribution systems

  • Sangroula, Uchit;Gnawali, Kapil;Koo, KangMin;Han, KukHeon;Yum, KyungTaek
    • Proceedings of the Korea Water Resources Association Conference
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    • 2019.05a
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    • pp.160-160
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    • 2019
  • Water is a limited source that needs to be properly managed and distributed to the ever-growing population of the world. Rapid urbanization and development have increased the overall water demand of the world drastically. However, there is loss of billions of liters of water every year due to leakages in water distribution systems. Such water loss means significant financial loss for the utilities as well. World bank estimates a loss of $14 billion annually from wasted water. To address these issues and for the development of efficient and reliable leakage management techniques, high efforts have been made by the researchers and engineers. Over the past decade, various techniques and technologies have been developed for leakage management and leak detection. These include ideas such as pressure management in water distribution networks, use of Advanced Metering Infrastructure, use of machine learning algorithms, etc. For leakage detection, techniques such as acoustic technique, and in recent yeats transient test-based techniques have become popular. Smart Water Grid uses two-way real time network monitoring by utilizing sensors and devices in the water distribution system. Hence, valuable real time data of the water distribution network can be collected. Best results and outcomes may be produced by proper utilization of the collected data in unison with advanced detection and management techniques. Long term reduction in Non Revenue Water can be achieved by detecting, localizing and repairing leakages as quickly and as efficiently as possible. However, there are still numerous challenges to be met and future research works to be conducted in this field.

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The analysis of EDM characteristics for Cu-electrode using LIGA process (LIGA 공정을 이용한 Cu전극의 방전가공 특성 분석)

  • Lee, S.H.;Jung, T.S.;Chang, S.S.;Kim, J.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.05a
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    • pp.383-386
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    • 2007
  • In this study, the analysis was carried out for Electrical Discharge Machining (EDM) characteristics of the Cu electrodes by LIGA process. The shape of electrodes has 324 pins for the cavity of BGA(Ball Grid Array) type test socket mold. BGA test sockets are used in the inspection process of the semi-conductor I.C chip manufacturing. In the work, the machining performance for EDM of the electrodes was analyzed on dimensional accuracy and wear rate. The dimensional accuracy was measured for dimension of the pins, pitch size between the pins and the roundness of corner edge using optical measuring machine.

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