• Title/Summary/Keyword: Auger

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Three-Temperature Modeling of Carrier-Phonon Interactions in Thin GaAs Film Structures Irradiated by Picosecond Pulse Lasers

  • Lee Seong-Hyuk;Lee Jung-Hee;Kang Kwan-Gu;Lee Joon-Sik
    • Journal of Mechanical Science and Technology
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    • v.20 no.8
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    • pp.1292-1301
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    • 2006

  • This article investigates numerically the carrier-phonon interactions in thin gallium arsenide (GaAs) film structures irradiated by subpicosecond laser pulses to figure out the role of several recombination processes on the energy transport during laser pulses and to examine the effects of laser fluences and pulses on non-equilibrium energy transfer characteristics in thin film structures. The self-consistent hydrodynamic equations derived from the Boltzmann transport equations are established for carriers and two different types of phonons, i.e., acoustic phonons and longitudinal optical (LO) phonons. From the results, it is found that the two-peak structure of carrier temperatures depends mainly on the pulse durations, laser fluences, and nonradiative recombination processes, two different phonons are in nonequilibrium state within such lagging times, and this lagging effect can be neglected for longer pulses. Finally, at the initial stage of laser irradiation, SRH recombination rates increases sufficiently because the abrupt increase in carrier number density no longer permits Auger recombination to be activated. For thin GaAs film structures, it is thus seen that Auger recombination is negligible even at high temperature during laser irradiation.

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Development of Screw-Type Handy Earth Auger for an Improved Digging Efficiency(I) - Design and Manufacture - (토양굴취력이 향상된 스크류형 경량 식혈기 개발(I) - 설계 및 제작 -)

  • Kim, Jin Hyun;Lee, Jae Hyun;Kim, Ki Dong;Ko, Chi Woong;Kim, Dong Geun
    • Journal of agriculture & life science
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    • v.50 no.3
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    • pp.31-41
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    • 2016

  • This study was conducted to develop a handy earth auger for use in sloppy and rugged forest terrains in order to reduce labor cost which comprises a major part of the production costs in forest afforestation projects. The first prototype is developed consist of two parts, the soil-digging screw and the battery power source. The specifications of the first prototype screw are: length of 170mm, a top diameter of 60mm, bottom diameter of 47mm, 23° angle for each helix, and a 50mm awl-head tip. The use of a single line of screw was selected for reduced weight. In addition, a power source of rotary DC Motor(WD-6G2425, WONILL, Korea) with a maximum torque of 30kgf-cm, rotation of 20-30rpm, K6G30C decelerator with a reduction ratio of 30:1 which could be used with no load for 48 was operated. In consideration of its weight, a lithium battery was utilized in line with the goal of developing a lightweight auger. In order to evaluate the performance of the first prototype, test sites were selected as 6 areas. The rotational force was found to be highest in area A(Solid area), followed by areas F(Mounted slope 40° area) and E(Mounted slope 30° area). It was also observed that in general, the rotational force increased along with the increase in soil depth with the maximum rotational force recorded at 10cm.

  • https://doi.org/10.14397/jals.2016.50.3.31 인용

A Study on the skin friction characteristics of SIP and the estimation of the nonlinear numerical modelling equation (SIP말뚝의 주면마찰특성 및 비선형 수치모델식 산정에 관한 연구)

  • 천병식;임해식;김도형
    • Proceedings of the Korean Geotechical Society Conference
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    • 2003.03a
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    • pp.153-160
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    • 2003

  • While the interests on the environmental problem during the construction are increasing, the use of low noise-vibration auger-drilled pilling is increasing to solve noise and vibration problem in pilling. Therefore, in Korea, SIP(Soil-Cement Injected Precast Pile) method is mainly used as auger-drilled pilling. However, there is no proper design criteria compatible with the ground condition of Korea, so which is most wanted. To improve and supplement this situation, direct shear tests between SIP pile skin interface and soil were executed on various conditions. Through the analysis of test results, skin resistance characteristics of SIP were investigated thoroughly. Also, the nonlinear unit skin resistance capacity model with SM, SC soil were suggested.

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