• Journal of IKEEE
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• v.1 no.1 s.1
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• pp.73-82
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• 1997

In this paper we analyzed, using Markov modeling, the performance of CSMA/CD over the wireless channel which is characterized by near-far effect, shadowing and Rayleigh fading. The analysis shows that throughput of CSMA/CD is degraded by channel error. However, if capture effect which arises from the randomness of power level of received signal due to the fading phenomena of electromagnetic waves is taken into consideration, the system performance is much improved and the system stability is also made better.

• Korean Journal of Optics and Photonics
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• v.19 no.1
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• pp.80-83
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• 2008

Optical tweezers are a tool that can use a tightly focused laser beam to trap and manipulate micron-sized dielectric particles that are immersed in a medium with lower refractive index. In this paper, the calculation of the trapping force of optical tweezers is presented. A nonparaxial Gaussian beam is used to represent a tightly focused Gaussian beam, and the FDTD (Finite-Difference Time-Domain) method is used for computing the electromagnetic field distributions in the dielectric medium. Scattered-field formulation is used for analytical expression of the incident fields. Using the electromagnetic field distribution from FDTD simulation, the trapping force is calculated based on Maxwell's stress tensor.

• Journal of the Korean Society of Radiology
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• v.7 no.3
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• pp.245-249
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• 2013

Neutron sources from photonuclear reaction with 46-MeV electron linear accelerator at Research Reactor Institute, Kyoto University used for resonance energy measurement of natural tantalum. BGO($Bi_4Ge_3O_{12}$) scintillation detectors used for measurement of the prompt gamma ray from the natural tantalum sample. The BGO spectrometer was composed geometrically as total energy absorption detector. The electric signal from the spectrometer was analyzed for TOF(Time-of-Flight) spectrum which is used identification of neutron capture resonance energy. In this study, the neutron energy region is from 1 to 200 eV, because of strong X-ray effect produced photonuclear reaction in Ta target, the measurement was performed to below 1 keV energy region. The resonance energy was compared with the evaluated values(ENDF/B-VI, Mughabghab). All of the resonances from 4.28 ~ 200 eV were seen in the present measurement except 144.3 eV resonance.

• Journal of the Korean Society of Radiology
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• v.8 no.6
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• pp.287-292
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• 2014

In this study, the neutron capture cross section of $^{180}Ta$(natural existence ratio: 0.012 %) obtain by measuring has been compared with the evaluated data for the capture data. In generally, the neutron capture resonance is defined as Breit-Wigner formula. The formula consists of the resonance parameters such as neutron width, total width and neutron width. However in the case of $^{180}Ta$, these are very poor experimental neutron capture cross section data and resonance information in below 10 eV. Therefore, in the study, we analyzed the neutron resonance of $^{180}Ta$ with the measuring the prompt gamma-ray from the sample. And the resonance was compared with the evaluated data by Mughabghab, ENDF/B-VII, JEFF-3.1 and TENDL 2012. Neutron sources from photonuclear reaction with 46-MeV electron linear accelerator at Research Reactor Institute, Kyoto University used for cross section measurement of $^{180}Ta(n,{\gamma})^{181}Ta$ reaction. $BGO(Bi_4Ge_3O_{12})$ scintillation detectors used for measurement of the prompt gamma ray from the $^{180}Ta(n,{\gamma})^{181}Ta$ reaction. The BGO spectrometer was composed geometrically as total energy absorption detector.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.12
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• pp.2899-2904
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• 2015

This paper introduces about the effect on $I_{DS}-V_{GS}$ characteristic of transistor that interface trap charge is created by damage due to heat in a 3D sequential inverter. A interface trap charge distribution in oxide layer in a 3D sequential inverter is extracted using two-dimensional device simulator. The variation of threshold voltage of top transistor according to the gate voltage variation of bottom transistor is also described in terms of Inter Layer Dielectric (ILD) length of 3D sequential inverter, considering the extracted interface trap charge distribution. The extracted interface trap density distribution shows that the bottom $HfO_2$ layer and both the bottom and top $SiO_2$ layer were relatively more affected by heat than the top $HfO_2$ layer with latest process. The threshold voltage variations of the shorter length of ILD in 3D sequential inverter under 50nm is higher than those over 50nm. The $V_{th}$ variation considering the interface trap charge distribution changes less than that excluding it.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.11
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• pp.954-962
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• 1998

Energy-trapped thickness vibrations of piezoelectric substrates are utilized in fabricating resonators and filters which have their operating frequencies in HF band. Normalized particle displacement distributions of the fundamental thickness shear vibration mode and overtone modes into the thickness direction in energy-trapped resonators and double-coupled filters were obtained by solving the wave equation and calculating the solved equations. These results show that as the number order of the harmonic mode in a energy-trapped resonator becomes larger, the degree of energy-trapping in the resonator increase, and if the conditions for energy-trapping become sufficiently weak, the energy-trapping effect of the harmonic mode which has the lower order disappears the earlier. Above simulation results were proved by the experiments.

• Electrical & Electronic Materials
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• v.4 no.2
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• pp.175-184
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• 1991

급속 열처리 방법으로 두께가 약 80.angs.C인 산화막을 성장시킨 후 950.angs.C와 1150.angs.C의 온도에서 15초-120초 동안 질화 및 재산화 공정을 수행하여 초 박막 구조의 질화 및 재산화된 질화 산화막을 성장하였다. 성장한 질화산 화막과 재 산화된 진화 산화막의 전기적 특성은 C-V, I-V, 전하 포획 및 TDDB 측정등을 통하여 분석하였다. 측정된 소자의 특성으로부터 질화 조건이 950.angs.C, 60초이고 재산화 조건이 1150.angs.C, 60초인 재산화된 질화 산화막은 전기적 스트레스 인가후에 전하 포획에 의한 평탄전압변화(.DELTA. $V_{fb}$ )와 계면 상태밀도( $D_{itm}$)의 증가가 산화막보다 적은 우수한 특성을 나타내는 것을 알 수 있었다.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.5
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• pp.17-27
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• 2000

In a SCH(separate confinement heterostructure) QW(quantum well) laser, we calculated the optical gain, the differential gain and recombination current in the QW and derived the bulk carrier density in the SCH region as a function of the QW current by using the analytical capture escape model. Based upon above relations, we found the optical gain and the differential gain correspond to the ratios of carrier and current injected into the QW.

• Electrical & Electronic Materials
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• v.9 no.9
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• pp.954-963
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• 1996

Particle displacement distributions of the fundamental thickness shear vibration mode and overtone modes in an energy-trapped single resonator and an energy-trapped double acoustically coupled filter were calculated. The effects of the width of a pair of partial eletrodes and the magnitude of the plate back of the resonator on the particle displacement distributions of its symmetric vibration mode and anti-symmetric vibration mode were investigated. And the effects of the width of a pair of partial eletrodes, the width of the gap between two pairs of partial electrodes and the magnitude of the plate back of the filter on the particle displacement distributions of its symmetric vibration mode and anti-symmetric vibration mode were investigated.

• Electrical & Electronic Materials
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• v.3 no.3
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• pp.195-204
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• 1990

본 논문에서는 컴퓨터를 근본으로 한 Deep Level Transient Spectroscopy (DLTS) 장치를 구성하고 이를 이용하여 P형 Si MOS 캐패시터의 Si- $SiO_{2}$ 계면상태를 측정하여 트랩의 활성화에너지와 포획단면적 그리고 계면트랩밀도를 조사하였다. 실리콘 band gap내에 연속적으로 분포하고 있는 계면트랩을 상세히 고찰하기 위해 quiescent 전압의 위치를 변화시키면서 0.1volt의 미소한 펄스를 MOS에 주입하여 그 각각이 분리된 트랩이라고 생각되는 매우 좁은 에너지 영역에서 나오는 DLTS신호를 측정하였다. 또한 quiescent 전압의 위치, 주입펄스전압의 진폭 그리고 rate window의 선택이 DLTS 신호에 미치는 영향 등을 조사하였다. 측정결과, 계면트랩의 활성화에너지는 가전자대로 부터 0.16-0.45eV이고 포획단면적은 1.3*$10^{-19}$~3.2*$10^{-15}$$cm^{2}$, 계면트랩밀도는 1.8*$10^{10}$ ~ 2.5*$10^{11}$$cm^{-2}$e$V^{-1}$로 측정되었다.