• 제목/요약/키워드: Pulse radiation

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Ecophysiological Interpretations on the Water Relations Parameters of Trees(IX) - Measurement of the Transpiration Rate by the Heat Pulse Method in a Quercus mongolica Stand - (수목(樹木)의 수분특성(水分特性)에 관(關)한 생리(生理)·생태학적(生態學的) 해석(解析)(IX) - Heat pulse법(法)을 이용(利用)한 신갈나무임분(林分)의 증산속도(蒸散速度) 측정(測定) -)

  • Han, Sang Sup;Kim, Sun Hee
    • Journal of Korean Society of Forest Science
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    • v.85 no.2
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    • pp.288-299
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    • 1996
  • This is the basic study to investigate the amount of transpirational water loss in thrifty mature Quercus mongolica stand by the heat pulse method. The differences of heat pulse velocity by direction and depth, differences of heat pulse velocity by dominant, codominant and suppressed trees, diurnal changes of heat pulse velocity due to the change of leaf water potential, vapor pressure deficit and radiation, and sap flow path way in sapwood by dye penetration were measured in stems. Finally the amounts of daily and annual transpiration in stand were calculated by the heat pulse velocity. The results obtained were summarized as follows : 1. Relationship between heat pulse velocity(V) and sap flow rate(SFR) was obtained as a equation of SFR=1.37V. 2. The sap flow rate was high in the order of dominant, codominant, and suppressed trees. The daily heat pulse velocity changed with radiation, temperature and vapor pressure deficit. 3. The heat pulse velocity showed the similar diurnal variation as the leaf water potential change. 4. The heat pulse velocity showed the highest value in May(4.0cm/hr in average), the lowest one in July(2.9cm/hr in average). 5. The heat pulse velocity in the same stem presented the highest value in the northern direction, medium in western, and the lowest in southern and eastern. 6. The heat pulse velocity in stem was highest in 0.5cm, medium in 1.0cm, and lowest in 1.5cm depth from the surface of stem. 7. The sap flow path way in stem showed sectorial straight ascent pattern in four sample trees. 8. The amount of sap flow(SF) was presented as a equation of $SF=1.37A{\cdot}V$(A: the cross-sectional area of sapwood, V: heat pulse velocity), and especially SF was larger in dominant tree than codominant and suppressed trees. 9. The amount of daily transpiration was 5.6ton/ha/day, and its composition ratio was 72% at day and 28% at night. 10. The amount of stand transpiration per month was largest in May(168ton/ha/month), lowest in July(125ton/ha/month). The amount of stand transpiration per year was 839ton/ha/year.

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CMOS Logic Design and Fabrication for Analyzing the Effect of Transient Radiation Damage (과도 방사선 피해 영향 분석을 위한 CMOS 논리 소자 설계 및 제작)

  • Jeong, Sang-Hun;Lee, Nam-Ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2012.05a
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    • pp.880-883
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    • 2012
  • In this paper, CMOS logic device, the INVERTER, NAND, NOR were designed and fabricated using 0.18um CMOS process for analyzing the effect of transient radiation damage. Fabricated logic devices were measured by applying a 1kHz input at 1.8V supply. As a result, the current consumption of less than 70uA and Rising time, Falling time was within a 4us. Experimental results transmission delays occurred when using a 50M cable for pulse radiation experiments.

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A Study on the Characteristic of the $^6Li$ Neutron Spectrometer ($^6Li$ 중성자분광계 특성 연구)

  • Choe, Seong-Ho;Kang, Sam-Woo;Lee, Kwang-Pill;Lee, Kyung-Ju;Hwang, Sun-Tae
    • Analytical Science and Technology
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    • v.5 no.1
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    • pp.57-61
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    • 1992
  • For the neutron spectrum measurement, $^6Li$ neutron spectrometer system is installed. The characteristic of the $^6Li$ detector are investigated using a $^{137}Cs$ and $^{207}Bi$ point source, and the neutron capture peaks and the pulse height spectrum using an $^{214}Am-Be$ neutron source are measured. Furthermore, the pulse height spectrum for the irradiation time variation from the (214)^Am-Be neutron source, and for the distance variation between detector and source, and the threshold variation of discriminator are measured.

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An Experimental Analysis for a High Pulse Radiation Induced Latchup Conformation (고준위 펄스방사선에 의한 전자소자 Latchup의 발생시험 및 분석)

  • Lee, Nam-Ho;Hwang, Young-Gwan;Jeong, Sang-Hun;Kim, Jong-Yeol
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.18 no.12
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    • pp.3079-3084
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    • 2014
  • When an integrated circuit device is burned out under high-intense radiation and device-level simulation that usually requires manufacturer's proprietary information is not available, experimental conformation of a failure mechanism is often the only choice. To distinguish Latchup from other causes experimentally, a new combination of multiple techniques have been developed and demonstrated. Power supply circumvention, hot-spot monitoring using an infrared camera, and supply current monitoring techniques were implemented for the conformation of the Latchup.

Development and Performance Testing of a Time-resolved OSL Measurement System

  • Hong, Duk-Geun;Kim, Myung-Jin
    • Journal of Radiation Protection and Research
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    • v.42 no.1
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    • pp.69-76
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    • 2017
  • Background: Time-resolved optically stimulated luminescence (TR-OSL) is a very useful method for calculating the lifetimes of crystalline quartz and feldspar. Materials and Methods: A compact TR-OSL system was developed, comprising a heater assembly manufactured using Kanthal wire, 2 powerful blue light-emitting diodes (LED, LXHL-PB02) for optical stimulation equipped with VIS liquid light guides, and a photomultiplier tube combined with an optical filter for luminescence detection. A pulse generated from the data acquisition board (NI PCI 6250) was used to initiate on/off signals in LED and TR-OSL measurements. Results and Discussion: The TR-OSL and background signals measured using this TR-OSL system using quartz samples were very similar to those reported in a previous study. Additionally, the lifetimes of the build-up and TR-OSL signals were calculated as $27.4{\pm}2.2{\mu}s$ and $30.3{\pm}0.6{\mu}s$, respectively, in good agreement with the findings of a previous study. Conclusion: It was concluded that the developed TR-OSL system was very reliable for TR-OSL signal measurements and lifetime calculations.

Effects of the Irradiated Current Mode PWM Controller of DC/DC Power Converter (DC/DC 전력 컨버터의 전류모드 PWM 제어기의 방사선 영향)

  • Lho, Young-Hwan;Hwang, Eui-Sung;Lho, Kyeoung-Su;Phouphanonh, Phouphanonh;Khamphoungeun, Khamphoungeun;Han, Chang-Won
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.685-692
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    • 2011
  • DC/DC switching power converters produce DC output voltages from different DC input sources. The converters can be used in regenerative braking of DC motors to return energy back in the supply, resulting in energy savings for the systems containing frequent stops. The current mode DC/DC converter is composed of a PWM (pulse width modulation) controller, a MOSFET, and inductor, etc. Pulse width modulation is applied to control and regulate the total output voltage. It is shown that the variation of threshold voltage at MOSFET and the offset voltage increase caused by radiation effects make the PWM pulse unstable. In the PWM operation, the missing pulses, the changes in pulse width, and a change in the period of the output waveform are studied by simulation program with integrated circuit emphasis (SPICE) and experiments.

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Development of Underwater Acoustic Performance Measurement System Using Pulse Tubes (펄스 튜브를 이용한 수중 음향 성능 측정 시스템 개발)

  • Seo, Yun-Ho;Kim, SangRyul;Lee, Sung-Min;Byun, Yang-Heon;Seo, Youngsoo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.04a
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    • pp.603-608
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    • 2014
  • Underwater acoustic materials are installed in order to reduce reflection, transmission and radiation of an underwater structure. The acoustic performance of the materials should be evaluated in accurately-controlled environment in terms of temperature and static pressure. In this paper, three pulse tubes, which is equipped with temperature and pressure controllers, are designed and developed to evaluate echo reduction and transmission loss for evaluating the performance below 10 kHz and 30kHz, respectively. The new procedures of the evaluation are suggested to improve the accuracy and the validation for the developed pulse tubes is carried out by comparing theoretical values to experimental ones.

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Upgrade of Neutron Energy Spectrometer with Single Multilayer Bonner Sphere Using Onion-like Structure

  • Mizukoshi, Tomoaki;Watanabe, Kenichi;Yamazaki, Atsushi;Uritan, Akira;Iguchi, Tetsuo;Ogata, Tomohiro;Muramatsu, Takashi
    • Journal of Radiation Protection and Research
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    • v.41 no.3
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    • pp.185-190
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    • 2016
  • Background: In order to measure neutron energy spectra, the conventional Bonner Sphere Spectrometers (BSS) are widely used. In this spectrometer, several measurements with different size Bonner spheres are required. Operators should, therefore, place these spheres in several times to a measurement point where radiation dose might be relatively high. In order to reduce this effort, novel neutron energy spectrometer using an onion-like single Bonner sphere was proposed in our group. This Bonner sphere has multiple sensitive spherical shell layers in the single sphere. In this spectrometer, a band-shaped thermal neutron detection medium, which consists of a LiF-ZnS mixed powder scintillator sheet and a wavelength-shifting (WLS) fiber readout, was looped to each sphere at equal angular intervals. Amount of LiF neutron converter is reduced near polar region, where the band-shaped detectors are concentrated, in order to uniform the directional sensitivity. The LiF-ZnS mixed powder has an advantage of extremely high light yield. However, since it is opaque, scintillation photons cannot be collect uniformly. This type of detector shows no characteristic shape in the pulse height spectrum. Subsequently, it is difficult to set the pulse height discrimination level. This issue causes sensitivity fluctuation due to gain instability of photodetectors and/or electric modules. Materials and Methods: In order to solve this problem, we propose to replace the LiF-ZnS mixed powder into a flexible and Transparent RUbber SheeT type $LiCaAlF_6$ (TRUST LiCAF) scintillator. TRUST LiCAF scintillator can show a peak shape corresponding to neutron absorption events in the pulse height spectrum. Results and Discussion: We fabricated the prototype detector with five sensitive layers using TRUST LiCAF scintillator and conducted basic experiments to evaluate the directional uniformity of the sensitivity. Conclusion: The fabricated detector shows excellent directional uniformity of the neutron sensitivity.

Design and Test Results of High-Power Pulse Generator System for Industrial Accelerator Application (산업용 가속기용 고출력 펄스시스템의 설계와 시험)

  • Jang, S.D.;Kim, S.H.;Yang, H.Y.;Cho, M.H.;Ko, I.S.;NamKung, W.
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.1370_1372
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    • 2009
  • A conventional linear accelerator system requires a flat-topped pulse with less than $\pm$ 0.5% ripple to meet the beam energy spread requirements and to improve pulse efficiency of RF systems. A a line-type pulsed modulator is widely used in pulsed power circuits for applications such as accelerators, radar, medical radiation, or ionization systems. The high-voltage pulse generator system with an output voltage of 284 kV, a pulse width of $10{\mu}s$, and a rise time of $0.84{\mu}s$ has been designed and fabricated to drive a klystron which has 30-MW peak and 60-kW average RF output power. The high-voltage test was performed using the klystron load. This thesis describes the design and test results of high-power pulse generator system for industrial accelerator application. The experimental results were analyzed and compared with the design.

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