• Title/Summary/Keyword: radiation wave

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A Study on Design of the Miniaturized Inverted-F Antenna Using Lumped Elements for Z-wave (집중소자를 이용한 Z-wave용 역 F형 안테나 소형화에 관한 연구)

  • Kwak, Min-Gil;Kim, Dong-Seek;Won, Young-Soo;Cho, Hyung-Rae
    • Journal of Advanced Marine Engineering and Technology
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    • v.33 no.8
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    • pp.1239-1245
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    • 2009
  • Currently, so many approaching methods are being developed to optimize the antenna size. In this paper, We fabricated Inverted-F type antenna attaching lumped components to solve the limitation of antenna size. Through experiments, a basic Inverted-F type antenna was fabricated and satisfied the adequate radiation pattern. After this, we researched the effect of antenna varied by matching circuit consist of chip type resistor, inductor, and capacitor. Using that elements, the antenna was matched at aim frequency. The proposed antenna's size is $7\;{\times}\;24\;mm$ that is very small size against the resonance frequence. Measuring the developed antenna, Its return loss was -18dB. Thus, this antenna can be used for Z-wave systems.

Cuboidal Infinite Elements for Soil-Structure-Interaction Analysis in Multi-Layered Half-Space (3차원 지반-구조물 상호작용해석을 위한 입방형 무한요소)

  • Seo, Choon-Gyo;Yun, Chung-Bang;Kim, Jae-Min
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.20 no.1
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    • pp.39-50
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    • 2007
  • This paper presents 3D infinite elements for the elastodynamic problem with multi-layered half-space. Five different types of infinite elements are formulated by using approximate expressions of multiple wave components for the wave function in multi-layered soil media. They are horizontal, horizontal-corner, vortical, vertical-corner and vertical-horizontal-comer infinite elements. The elements can effectively be used for simulating wane radiation problems with multiple wave components. Numerical example analyses are presented for rigid disk, square footings and embedded footing on homogeneous and layered half-space. The numerical results show the effectiveness of the proposed infinite elements.

Measurement of electro-physiological changes in the brain exposed to eletromagnetic wave radiation (전자파에 노출된 생체두부의 전기생리적 변화의 측정에 관한 연구)

  • 이준하;신현진;이상학;유동수;이무영;김성규
    • Progress in Medical Physics
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    • v.5 no.2
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    • pp.35-43
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    • 1994
  • Electromagnetic wave may induce effect and damage on the bio-body, either by electric fields of magnetic fields. We measure electrophysiological changs in rabbit's brain exposed to 2.45GHz micro wave(power density 40mW/cm$^2$) which distance 30cm from the source. In order to process the bio-electrical signal (EEG), used pre-amplifier module with self-made and Digtal analyzer computer system. Spectal analysis of the EEG showed variable power in the frequency range(1~30Hz) through each exposure time(10min, 20min, 30min) before and after. In effectively measured by the bio-electrical signal processing and can found threshold of minmal permissible exposure and lethal exposure.

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Heat flow Analysis of Heat Sink Using the Computational Simulation (전산모사를 이용한 히트싱크의 열 유동 해석)

  • Lim Song Chul;Chang Si Young;Kim Hyon Tae;Lee Dong Heon;Kang Kae Myung
    • Korean Journal of Materials Research
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    • v.14 no.7
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    • pp.522-528
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    • 2004
  • Heat analysis of the plate type and wave type heat sink were carried out by using computational simulation. The heat resistance and air flow of two heat sink models were analysed according to natural and forced convection condition and positions of fan. When a fan was at the position of z-axis and y-axis in forced convection, the heat resistances of plate type heat sink were $0.17^{\circ}C/W$, and $0.28^{\circ}C/W$ respectively. In the case of wave type heat sink, they were $0.18^{\circ}C/W$ and $0.53^{\circ}C/W$. As the air flow velocities were averagely $0.386\;m/s\~3.269\;m/s$, air flow velocity of plate type heat sink was faster than that of wave type. In this experiment, it was observed that the plate type heat sink showed a good ability of heat radiation comparing with wave type one.

A Study on the Characteristics of a 400W, 7.9~8.4GHz Double-Slot Coupled-Cavity Traveling-Wave Tube (400W, 7.9~8.4GHz 이중슬롯 결합공진기 진행파관 증폭기 특성 연구)

  • Kim, Hyoung-Jong;Kim, Hae-Jin;Choi, Jin-Joo;So, Jun-Ho
    • Journal of the Korea Institute of Military Science and Technology
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    • v.12 no.6
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    • pp.760-767
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    • 2009
  • This thesis focuses on the study of high-power, coupled-cavity traveling-wave tube(CCTWT) for radar applications. The CCTWT employed a reentrant double-slot staggered RF cavity structure. Computational analysis of the X-band, double-slot staggered structures is carried out through the use of HFSS code, which solves Maxwell's equations fully in three-dimensions. The non-linear, large-signal performance of CCTWTs are predicted from numerical simulations using a three-dimensional particle-in-cell code, MAGIC3D. With beam voltage set to 12.7~13kV and beam current at 300mA, the CCTWT produces a saturated radiation power of 350~430W, corresponding to an electronic efficiency of 8.9~11.2% and a gain of 23.7~24.2dB within a frequency range of 7.9~8.4GHz.

Energy extraction from the motion of an oscillating water column

  • Wang, Hao;Falzarano, Jeffrey M.
    • Ocean Systems Engineering
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    • v.3 no.4
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    • pp.327-348
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    • 2013
  • An Oscillating Water Column (OWC) is a relatively practical and convenient device that converts wave energy to a usable form, which is electricity. The OWC is kept inside a fixed truncated vertical cylinder, which is a hollow structure with one open end submerged in the water and with an air turbine at the top. This research adopts potential theory and Galerkin methods to solve the fluid motion inside the OWC. Using an air-water interaction model, OWC design for energy extraction from regular wave is also explored. The hydrodynamic coefficients of the scattering and radiation potentials are solved for using the Galerkin approximation. The numerical results for the free surface elevation have been verified by a series of experiments conducted in the University of New Orleans towing tank. The effect of varying geometric parameters on the response amplitude operator (RAO) of the OWC is studied and modification of the equation for evaluating the natural frequency of the OWC is made. Using the model of air-water interaction under certain wave parameters and OWC geometric parameters, a computer program is developed to calculate the energy output from the system.

Computational Simulation of Heat flow phenomena in Newly Designed Heat Sinks (뉴 디자인된 히트싱크의 열 유동 현상 컴퓨터 시뮬레이션)

  • Lim Song Chul;Choi Jong Un;Kang Kae Myung
    • Korean Journal of Materials Research
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    • v.14 no.11
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    • pp.775-779
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    • 2004
  • For improvement of heat dissipation performance, heat analysis is conducted on the newly designed heat sinks under two convection conditions by using computational fluid dynamics(CFD). Three types of heat sink, plate, wave and top vented wave, are used, and convection conditions are the variations of gravity direction at natural convection and of fan location at forced convection. The results of analysis showed that the heat resistances of top vented wave heat sink were $0.17^{\circ}C$/W(forced convection) and $0.48^{\circ}C$/W(natural convection). In the case of natural convection, gravity direction affected heat flow change, and protection against heat performance was superior in case of z-axis gravity direction. Under the forced convection, all the heat sinks revealed superior thermal characteristics in the fan position of z-axis rather than y-axis. In this study, it was observed that the top vented wave type heat sink showed the best ability of heat radiation comparing with the others.

Fast Defect Detection of PCB using Ultrasound Thermography (초음파 서모그라피를 이용한 빠른 PCB 결함 검출)

  • Cho, Jai-Wan;Jung, Hyun-Kyu;Seo, Yong-Chil;Jung, Seung-Ho;Kim, Seung-Ho
    • Proceedings of the KIEE Conference
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    • 2005.10b
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    • pp.273-275
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    • 2005
  • Active thermography is being used since several years for remote non-destructive testing. It provides thermal images for remote detection and imaging of damages. Also, it is based on propagation and reflection of thermal waves which are launched from the surface into the inspected component by absorption of modulated radiation. For energy deposition, it use external heat sources (e.g., halogen lamp or convective heating) or internal heat generation (e.g., microwaves, eddy current, or elastic wave). Among the external heat sources, the ultrasound is generally used for energy deposition because of defect selective heating up. The heat source generating a thermal wave is provided by the defect itself due to the attenuation of amplitude modulated ultrasound. A defect causes locally enhanced losses and consequently selective heating up. Therefore amplitude modulation of the injected ultrasonic wave turns a defect into a thermal wave transmitter whose signal is detected at the surface by thermal infrared camera. This way ultrasound thermography(UT) allows for selective defect detection which enhances the probability of defect detection in the presence of complicated intact structures. In this paper the applicability of UT for fast defect detection is described. Examples are presented showing the detection of defects in PCB material. Measurements were performed on various kinds of typical defects in PCB materials (both Cu metal and non-metal epoxy). The obtained thermal image reveals area of defect in row of thick epoxy material and PCB.

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Analysis of Electromagnetic Wave for Spark Plug Cable in Distributorless Spark Ignition System (무배전기식 불꽃 점화 시스템의 점화 플러그 케이블에서 발생되는 전자파의 분석)

  • Kang, Sang-Won;Choe, Gwang-Je;Hur, Jung
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.13 no.2
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    • pp.121-125
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    • 2013
  • It is an analysis about electromagnetic wave which is generated from a Spark plug cable of Distributorless spark ignition system. In case of Distributorless spark ignition system, high frequency generation is an ignition coil and Spark plug cable and Spark plug could be activated with electromagnetic wave radiation antenna. I calculated a resonant frequency with HFSS by measuring length of Spark plug cable and Spark plug. The antenna was considered as ${\lambda}/4$ monopole antenna in this calculation. According to power spectrum measurement analysis of engine room radiated electromagnetic wave and calculated Resonant frequency, it is possible to find out that the Distributorless spark ignition system radiates high frequency energy in certain frequency band.

Applications of Light-emitting Properties and Functional Selective-wave Lightings of LED Lamp (LED 램프의 발광 특성과 선택파장 기능성 응용)

  • Soh, Dea-Wha;Hong, Sang-Jeen;Park, Jong-Dae;Hah, Tae-Min;Kim, Ji-Woo
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2012.10a
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    • pp.856-859
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    • 2012
  • In order to cultivate vegetables in plastic greenhouse or housing facilities it was investigated properties of radiation and functions of LED lamp and proposed application possibility. Against presently existing method of obtaining blue and red colored wave lights needed to plants growing, it was used white LED and red LED to investigate growing conditions as well as brightness and color sense with working condition. And also it was presented lighting system of selective wave functions to promote plant growth.

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