• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권3호
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• pp.1030-1050
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• 2021

The edges with "bridge characteristic" play the role of connecting the communication between regions in power optical cable network. To solve the problem of mining edges with "bridge characteristic" in provincial power optical cable network, the complex power optical cable network model is constructed. Firstly, to measure the generated potential energy of all nodes in n-level neighborhood local structure for one edge, the n-level neighborhood local structure topological potential is designed. And the minimum connected chain attenuation is designed to measure the attenuation degree caused by substituted edges. On the basis of that, the minimum connected chain attenuation topological potential based measurement is designed. By using the designed measurement, a bridge-edges mining algorithm is proposed to mine edges with "bridge characteristic". The experiments are conducted on the physical topology of the power optical cable network in Jilin Province. Compared with that of other three typical methods, the network efficiency and connectivity of the proposed method are decreased by 3.58% and 28.79% on average respectively. And the proposed method can not only mine optical cable connection with typical "bridge characteristic" but also can mine optical cables without obvious characteristics of city or voltage, but it have "bridge characteristic" in the topology structure.

• 한국항해학회지
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• 제20권3호
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• pp.97-105
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• 1996

Authors have studied characteristics evalution on semianechoic chamber. And authors also find that in case of low frequencies like from 30MHz to 100MHz there are big differencies between the calculated and the measured site attenuation in semianechoic chamber made with ferrite grid. This is on account of not being considered the mutual coupling effects between two antennas. Accordingly Authors calculated site attenuation due to mutual coupling effects and compared the measured site attenuation with the calculated site attenuation with mutual coupling correction. As a result good agreement between site attenuation, measured or calculated is obtained.

• 한국음향학회지
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• 제7권2호
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• pp.20-25
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• 1988

본 연구는 소음전파에 대한 옥외실험과 축적 음향모형실험에 의해서 지표면에 의한 초과감쇠 특징을 밝힌 것으로써, 옥외실험에 의한 소음전파감쇠는 음향출력이 큰 소형엔진을 사용하여, 거리감쇠로부터 산출한 실측의 초과감쇠와 Log(D/(Hs+Hr))의 관계를 확인했다. 그 결과 소음전파감쇠는 풍향, 주파수에 따라 다르며 직선회귀 된다는 것을 알 수 있었다. 그리고, 지표면상의 초과감쇠치는 통기저항을 이용해서 Log(D/Hs+Hr))을 파라미터로써 구할 수 있었고, 가장 적당한 통기저항$\sigma$는 실측의 초과감쇠치와 임의의 $\sigma$에 대한 $L=-20Log\mid1+(r_1/r_2)Qexp(ik, \bigtriangleup r)\mid$ 식의 평균자승 오차가 가장 적어질 때 결정된다. 모형의 지표로써 축척 1/40의 모형실험으로, 큰 무향실내에서 거리감쇠의 측정을 한 결과, 실측치와의 대응이 충분하다는 것을 확인했다.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.241-246
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• 2024

The study was carried out by numerical integration based on the diffraction properties and elemental composition. The elemental compositions of breast tissues in the literature were tested. The photon attenuation coefficients calculated using the recent elemental composition were found within 0.2-16% for adipose tissue and within 0.04-17% for glandular tissue with the experimental reference data. The attenuation coefficients of cancerous breast tissue calculated according to the elemental content previously measured in breast cancer patients were found within 0-17% with experimental data in the literature. The attenuation coefficients are of great interest to medical research. To calculate realistic attenuation coefficients, the characteristic coherent scatter, which is most intense at small angles, must be considered. For this reason, experimentally measured form factor data were reviewed, and the most compatible one with the theoretical form factor data produced in this study was used at low momentum transfer x (0 < x ≤ 8 nm^-1). The differential linear coherent scattering distributions were calculated for an energy value of 17.44 keV and compared with their experimental counterparts.

• 한국지반공학회논문집
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• 제36권12호
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• pp.7-16
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• 2020

본 연구는 음향학적 기법을 이용하여 지반의 투수계수를 산정하는 새로운 방법을 제시하였다. 연구를 위하여 Biot의 특성 진동수(Characteristic Frequency) 와 지반의 투수계수의 연관성이 포화된 지반에서만 나타나는 것을 확인할 수 있도록 음파의 감쇠 및 전파속도 특성을 포화된 시료와 건조된 시료에 대하여 측정/비교 하였다. 본 연구에서의 시험결과는 특성 진동수는 포화된 지반에서만 나타나며, 음파의 감쇠 특성으로 부터 얻은 특성 진동수와 전파속도 특성으로 부터 얻은 특성 진동수가 서로 매우 유사한 범위를 나타내었다. 한편 음파의 전파속도로 부터 얻은 결과가 감쇠 특성으로부터 얻은 결과보다 판독성이 좀 더 좋은 것으로 나타났다. 또한 본 시험결과를 동일한 시료에 대한 정수위 투수시험결과와 비교했을때 서로가 합리적으로 상응하는 결과를 나타내었으며, 본 연구에서 사용된 음향학적 기법이 사질토 또는 실트질 사질토의 투수계수를 구할 수 있는 비파괴 시험으로 사용될 수 있는 가능성을 보여 주었다.

• Nuclear Engineering and Technology
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• 제49권7호
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• pp.1483-1488
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• 2017

In order to predict and control the environmental and health impacts of ionizing radiation in environmental sources such as groundwater, it is necessary to identify the radionuclides present. Beta-emitting radionuclides are frequently identified by measuring their characteristic energy spectra. The present work shows that self-attenuation effects from volume sources result in a geometry-dependent shift in the characteristic spectra, which needs to be taken into account in order to correctly identify the radionuclides present. These effects are shown to be compounded due to the subsequent shift in the photon spectra produced by the detector, in this case an inorganic solid scintillator ($CaF_2:Eu$) monitored using a silicon photomultiplier. Using tritiated water as an environmentally relevant, and notoriously difficult to monitor case study, analytical predictions for the shift in the energy spectra as a function of depth of source have been derived. These predictions have been validated using Geant4 simulations and experimental results measured using bespoke instrumentation.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 추계학술대회 논문집
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• pp.127-132
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• 2003

In a today industry, the welding is doing a many portion in structure manufacture. This study is simulated heat of heat-effected zone and researched a mechanical properties and ultrasonic characteristic in used the SS400 and the STS304. As the result mechanical properties of steel that become drawing decreased because of remaining stress by strain gardening according as simulated heat temperature rises, but according as temperature rises in material that do simulated heat after have done annealing, mechanical propensity was improved. The velocity and attenuation become different by effect of remaining stress than effect of material internal microstructure in ultrasonic wave test. In the case of STS304, there was change in mechanical properties by effect that is by strain hardening, but there was no change in material that simulated heat after annealing. When become drawing in ultrasonic waves test, according as simulated heat temperatures rise, change of attenuation coefficient is looked, but material that simulated heat after annealing was no change almost both the volocity and attenuation.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.232-239
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• 2006

Guided wave techniques have been used for pipeline inspection because of the long range inspection capability of guided waves. One of main concerns of these technique is how ones decide the axial interval of sensors when they are utilized for pipeline inspection. This question is related to the characteristic of cylindrical guided wave propagation, especially wave attenuation. Thus, attenuation of fundamental longitudinal guided wave propagating liquid-filled steel pipes is numerically investigated in the paper. Several liquids such as water, diesel oil, castor oil etc. are considered for the filing materials in the pipes. Sink is considered for numerical models for abandoning standing wave modes; hence, the attenuation dispersion curves become much simpler. Those attenuation calculations can be utilized for guided-wave-based nondestructive testing of pipelines when one inspects pipelines, using monitoring sensors, which are installed outside pipes.

• Structural Engineering and Mechanics
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• 제61권1호
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• pp.143-160
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• 2017

The paper studies the attenuation of the axisymmetric longitudinal waves propagating in the bi-layered hollow cylinder made of linear viscoelastic materials. Investigations are made by utilizing the exact equations of motion of the theory of viscoelasticity. The dispersion equation is obtained for an arbitrary type of hereditary operator of the materials of the constituents and a solution algorithm is developed for obtaining numerical results on the attenuation of the waves under consideration. Specific numerical results are presented and discussed for the case where the viscoelasticity of the materials is described through fractional-exponential operators by Rabotnov. In particular, how the rheological parameters influence the attenuation of the axisymmetric longitudinal waves propagating in the cylinder under consideration, is established.

• 대한전기학회논문지
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• 제36권9호
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• pp.685-690
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• 1987

Adaptive design of IIR digiral filters using equation error method has been studied. In this paper, a design technique of IIR digital filters using output error method with adaptive compensator is presented. In computer simulation results, it is shown that flat response characteristic in pass-band, below-40[dB] attenuation characteristic in stop-band, sharf cut-off characteristic in transition-band, and phase characteristic is linearin pass-band.