• Title/Summary/Keyword: equivalent source

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Research on the Accuracy of Prediction of Radiation Emission from PCB within an Enclosure with a Rectangular Aperture (직사각형 개구면이 있는 함체 내부에 위치한 PCB로부터의 복사 방출 예측 기법의 정확도 연구)

  • Park, Yong-Bae;Jung, Ki-Bum;Chung, Yeon-Choon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.19 no.9
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    • pp.957-967
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    • 2008
  • In this paper, we propose the prediction algorithm of radiation emission from the PCB in an enclosure with a rectangular aperture. PCB scanner is used to measure the near field, which is substituted with an equivalent electric dipole source. Green function and Fourier transform are utilized to represent the electromagnetic fields within and outside the enclosure, respectively. The radiation emission is estimated by using the mode matching technique and surface equivalent theorem. The theoretical results are compared with the measurement to check the accuracy of our analysis.

Extraction of Passive Device Model Parameters Using Genetic Algorithms

  • Yun, Il-Gu;Carastro, Lawrence A.;Poddar, Ravi;Brooke, Martin A.;May, Gary S.;Hyun, Kyung-Sook;Pyun, Kwang-Eui
    • ETRI Journal
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    • v.22 no.1
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    • pp.38-46
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    • 2000
  • The extraction of model parameters for embedded passive components is crucial for designing and characterizing the performance of multichip module (MCM) substrates. In this paper, a method for optimizing the extraction of these parameters using genetic algorithms is presented. The results of this method are compared with optimization using the Levenberg-Marquardt (LM) algorithm used in the HSPICE circuit modeling tool. A set of integrated resistor structures are fabricated, and their scattering parameters are measured for a range of frequencies from 45 MHz to 5 GHz. Optimal equivalent circuit models for these structures are derived from the s-parameter measurements using each algorithm. Predicted s-parameters for the optimized equivalent circuit are then obtained from HSPICE. The difference between the measured and predicted s-parameters in the frequency range of interest is used as a measure of the accuracy of the two optimization algorithms. It is determined that the LM method is extremely dependent upon the initial starting point of the parameter search and is thus prone to become trapped in local minima. This drawback is alleviated and the accuracy of the parameter values obtained is improved using genetic algorithms.

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Theoretical Analysis of Frequency Dependent Input Resistance in RF MOSFETs (RF MOSFET의 주파수 종속 입력 저항에 대한 이론적 분석)

  • Ahn, Jahyun;Lee, Seonghearn
    • Journal of the Institute of Electronics and Information Engineers
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    • v.54 no.5
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    • pp.11-16
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    • 2017
  • The frequency dependent input resistance observed in RF MOSFETs is analyzed in detail by deriving pole and zero frequency equations from a simplified input equivalent circuit. Using this theoretical analysis, we find that the reduction effect of the input resistance in the low frequency region arises from the channel resistance between source and pinch-off region in the saturation region. This channel resistance effect on the low frequency reduction of the input resistance is physically validated by performing small-signal equivalent circuit modeling with varying the channel resistance.

Development of an insulation performance measurement unit for full-scale LNG cargo containment system using heat flow meter method

  • Lee, Jin-sung;Kim, Kyung-su;Kim, Yooil
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.10 no.4
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    • pp.458-467
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    • 2018
  • Efforts have been made in this paper to develop the measuring device for the insulation performance of full scale NO96 LNG CCS. The facility was designed to maintain environmental conditions which are similar to operation conditions of full scale LNG CCS. In the facility, the heat sink boundary was kept cryogenic temperature by cold chamber which contains liquefied nitrogen and heat source boundary was made by external case heated by natural convection. Heat Flow Meter method (HFM) was applied to this facility, hence Heat Flux Sensors (HFS) were attached to specimen. The equivalent thermal conductivity of full scale NO96 unit box was targeted to measure and PUF of same size was used for the calibration test. Additionally, the finite element analysis was carried out to check the performance of the developed test facility and experimental results were also compared with those predicted by the numerical method.

Design and evaluation of the thermal capability to secure a working time of cryogenic explosion-proof camera in LNG carrier tank

  • Kang, Geun-Il;Kwak, Si-Young;Park, Chun-Seong
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.9 no.5
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    • pp.568-576
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    • 2017
  • With an increase in the usage of LNG, there is a heightened interest about its safety aspects regarding the explosion of LNG carrier tank. The need for a cryogenic explosion-proof camera has increased. The camera has to work in cryogenic environment (below $-160^{\circ}C$) in LNG carrier. This study conducted design and heat transfer analysis of cryogenic camera to secure working time in limitation of heat source. The design with gap width of double pane windows was conducted based on simple vertical cavity model to insulate from cryogenic environment. The optimal gap width was 12.5 mm. For effective analysis considering convection within the camera, equivalent thermal conductivity method was adopted with ABAQUS. The working time of the camera predicted was over 10 h at warm-start condition. In cold-start condition, it required about 5 h of pre-warming time to work. The results of analysis were compared with the ones of the actual cryogenic test.

Derivation of Numerical Equivalent Model of Vibration Isolator using Pseudoelastic SMA Mesh Washer (의탄성 형상기억합금 메쉬 와셔가 적용된 수동형 진동절연기의 수학적 등가모델 도출)

  • Kwon, Sung-Cheol;Jeon, Su-Hyeon;Oh, Hyun-Ung
    • Journal of Aerospace System Engineering
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    • v.8 no.3
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    • pp.6-13
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    • 2014
  • A passive launch and on-orbit vibration isolator using SMA(Shape Memory Alloy) washer for both the structural safety of the micro-vibration source by attenuating the transmitted force under launch loads and the micro-vibration isolation during their on-orbit operation has been proposed, which does not require the additional launch locking mechanism. To measure the characteristics of SMA mesh washer, we performed compressive loading tests with a single SMA mesh washer and a vibration isolator using SMA mesh washer. The numerical equivalent model of vibration isolator using SMA mesh washer composed of two spring and viscous damping elements has been verified that both stiffness and viscous damping varied with respect to compressed deformations. In addition, the effectiveness of launch loads and micro-vibration reduction has been investigated through the dynamic characteristics measurement test of cooler assembly combined with passive vibration isolator.

Life Cycle Cost Analysis of Primary Cooling System by Systematic Support Cost (각종지원금제도에 의한 냉열원시스템의 라이프 사이클 코스트 분석)

  • Kim, C.M.;Jung, S.S.;Choi, C.H.
    • Journal of the Korean Solar Energy Society
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    • v.22 no.4
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    • pp.97-106
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    • 2002
  • The purpose of this study is to analyze the life cycle cost of primary cooling system by systematic support cost. Life Cycle Cost(LCC) is the process of making an economic assessment of an item, area, system, or facility by considering all significant costs of ownership over an economic life, expressed in terms of equivalent costs. The essence of life cycle costing is the analysis of equivalent costs of various alternative proposals. In order to select economical primary cooling system in early heat source plan stages, the research investigates cost items and cost characteristics during project process phases such as planning/design, construction, maintenance /management, and demolition/sell phases. The study also analyze the life cycle cost by capacity leading to suggest the most economical primary cooling system by systematic support cost.

Development and Characterization of Multi-Segmented Tissue Equivalent Proportional Counter for Microdosimetry (마이크로 도시메트리용 다분할 조직등가비례계수기의 개발과 특성 평가)

  • Nam, Uk-Won;Park, Won-Kee;Lee, Jaejin;Pyo, Jeonghyun;Moon, Bong-Kon;Moon, Myung Kook;Lim, Chang Hwy;Lee, Suhyun;Kim, Sunghwan
    • Journal of Sensor Science and Technology
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    • v.24 no.2
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    • pp.101-106
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    • 2015
  • We designed, developed and characterized a multi-segmented tissue equivalent proportional (TEPC) counter for microdosimetry. The energy resolution of the multi-segmented TEPC was about 12% for $^{241}Am$ 5.45 MeV alpha particles. The resolution was better than 33% for a single un-segmented TEPC. A compact and low power consumption TEPC could be made by using digital pulse processor (DPP). We also successfully calibrated the TEPC by using $^{252}Cf$ standard neutron source in Korea Research Institute of Standards and Science (KRISS). According to the results, the TEPC is useful for several application of radiation monitoring such as a neutron monitor, air crew monitor and space dosimeter.

A Study on the Noise Characteristics and Assessment of Fighter and Civil Aircraft (전투기와 민간 항공기의 소음특성과 평가에 관한 연구)

  • Ju, Kyung-Min;Lee, Jong-Seok;Kim, Deok-Han;Song, Hwa-Young;Lee, Dong-Hoon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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    • pp.227-230
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    • 2005
  • This paper describes the problems in measuring and evaluating the aviation noises and the differences on the noise characteristics between fighter and civil aircraft. From a standpoint of the duration time for aviation noise and the dynamic characteristics related with the sampling time, the measured values for landing and taking-off noises from the fighter are presented and explained in comparison with those from the civil aircraft. And also the aviation noises by the fighter and civil aircraft are evaluated by equivalent sound level and WECPNL, respectively. From the obtained results, it is recommended that the duration time and dynamic characteristics be deeply considered in evaluating and measuring the aviation noises, since they have a great influence on the final assessment results. As the number of flight is not sufficient and the noise source is strong impulse type, moreover, the aviation noise should be assessed by WECPNL.

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Monte Carlo-based identification of electron and proton edges for calibration of miniaturized tissue equivalent proportional counter

  • Mingi Eom;Sukwon Youn;Sung-Joon Ye
    • Nuclear Engineering and Technology
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    • v.55 no.11
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    • pp.4167-4172
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    • 2023
  • Miniaturized tissue equivalent proportional counters (mini-TEPCs) are proper for radiation dosimetry in medical application because the small size of the dosimeter could prevent pile-up effect under the high intensity of therapeutic beam. However, traditional methods of calibrating mini-TEPCs using internal alpha sources are not feasible due to their small size. In this study, we investigated the use of electron and proton edges on Monte Carlo-generated lineal energy spectra as markers for calibrating a 0.9 mm diameter and length mini-TEPC. Three possible markers for each spectrum were calculated and compared using different simulation tools. Our simulations showed that the electron edge markers were more consistent across different simulation tools than the proton edge markers, which showed greater variation due to differences in the microdosimetric spectra. In most cases, the second marker, yδδ, had the smallest uncertainty. Our findings suggest that the lineal energy spectra from mini-TEPCs can be calibrated using Monte Carlo simulations that closely resemble real-world detector and source geometries.