• Nuclear Engineering and Technology
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• 제48권5호
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• pp.1154-1161
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• 2016

The heat transfer characteristics between liquid lead bismuth eutectic (LBE) and helium are of great significance for the two-loop cooling system based on an accelerator-driven system (ADS). This paper presents an experimental study on the resistance characteristics and heat transfer performance in a LBE-helium experimental loop of ADS. Pressure drops in the LBE loop, the main heat transfer, and the coupled heat transfer characteristics between LBE and helium are investigated experimentally. The temperature of LBE has a significant effect on the LBE thermo-physical properties, and is therefore considered in the prediction of pressure drops. The results show that the overall heat transfer coefficient increases with the increasing helium flow rate and the decreasing inlet temperature of helium. Increasing the LBE Reynolds number and LBE inlet temperature promotes the heat transfer performance of main heat transfer and thus the overall heat transfer coefficient. The experimental results give an insight into the flow and heat transfer properties in a LBE-helium heat exchanger and are helpful for the optimization of an ADS system design.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권7호
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• pp.2339-2355
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• 2021

In this paper, a joint probabilistic data association algorithm based on loss function (LJPDA) is proposed so that the computation load and accuracy of the multi-target tracking algorithm can be guaranteed simultaneously. Firstly, data association is divided in to three cases based on the relationship among validation gates and the number of measurements in the overlapping area for validation gates. Also the contribution coefficient is employed for evaluating the contribution of a measurement to a target, and the loss function, which reflects the cost of the new proposed data association algorithm, is defined. Moreover, the equation set of optimal contribution coefficient is given by minimizing the loss function, and the optimal contribution coefficient can be attained by using the Newton-Raphson method. In this way, the weighted value of each target can be achieved, and the data association among measurements and tracks can be realized. Finally, we compare performances of LJPDA proposed and joint probabilistic data association (JPDA) algorithm via numerical simulations, and much attention is paid on real-time performance and estimation error. Theoretical analysis and experimental results reveal that the LJPDA algorithm proposed exhibits small estimation error and low computation complexity.

• 한국지반환경공학회 논문집
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• 제13권11호
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• pp.81-91
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• 2012

이 논문은 폐기물 매립지에 사용되는 차수시설로서 토목섬유-흙 시스템의 접촉면에 대한 동적거동을 예측하기 위하여 제안된 교란도함수의 확률적 특성 분석에 대한 내용을 다루고 있다. 우선 다기능 접촉면 전단시험기(M-PIA)에 의한 다수의 시험자료를 활용하여 토목섬유-흙의 접촉면에 대한 교란도함수 모델의 매개변수를 보정하고 그 통계특성을 산정하였다. 다음으로 화학적인자와 상재하중의 영향을 고려한 교란도함수의 확률적 특성분석을 위하여, 산정된 A와 Z의 통계특성과 매우 효율적인 샘플링기법인 LHS기법을 적용함으로써 교란도함수 모델의 확률적 특성인 평균, 변동계수 및 분포형태를 분석하였다. 그 결과로서 ${\xi}_D$의 수준에 따라 교란도함수의 변동성은 약 최소 10%에서 최대 28% 정도로 나타났으며, 분포형태는 대부분의 ${\xi}_D$수준에서 Weibull 분포가 가장 적합한 것으로 나타났다. 이 연구를 통하여 획득한 교란도함수의 확률특성을 활용하면 향후 접촉면 전단강도의 불확실성과 변동성을 정량적으로 명확하게 고려할 수 있는 토목섬유-흙 접촉면의 확률론적 안전성 평가기법의 개발이 가능할 것으로 판단된다.

• 한국산학기술학회논문지
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• 제19권5호
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• pp.64-71
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• 2018

본 논문은 호기성 생분해도를 통하여 유가공 폐수의 기질특성을 파악하기 위하여 수행되었다. 유기물 중 빨리 분해되는 물질(Ss)은 SCODcr 기준을 84.2 %로 조사되었는데, 이는 수산물 가공폐수의 75.8~77.9 %, 돈사폐수의 58.2 % 보다 높은 것으로 조사되었다. 생물학적 분해 불가능한 용존성 유기물(SI)의 비율은 5.6~6.4 %로, 미생물 신진대사에 의해 발생 되는 inert 물질 비율(SIi)은 3.6~3.7 %로 조사되었다. 생물학적 분해 불가능한 용존성 유기물 성분의 함유 계수(YI) 0.092~0.099로, 미생물 신진대사로 생성되는 inert 물질의 생성계수(Yp)는 0.039~0.040으로 산정되었다. 유기물 성분 계수 분석결과, 유가공 폐수의 용존성 유기물 약 91.0 %가 생물학적으로 분해 가능한 물질이고, 이중 약 92.5 %가 빨리 분해되는 Ss 성분으로 조사되었다. 또한 총유기물(TCODcr) 중에 생물학적 분해 가능한 유기물의 비율은 89.3 %로 조사되었다. 생물학적 분해 불가능한 용존성 유기물(SI) 성분은 3.0 %, 생물학적 분해 불가능한 부유성 물질(XI) 성분은 7.7 %로 비교 대상 폐수보다 낮게 조사되었는데, 이는 유가공 폐수가 호기성 생분해도가 크다는 것을 의미한다.

• Wind and Structures
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• 제31권1호
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• pp.31-41
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• 2020

A new type of bridge deck section consisting of four-box decks, two side decks for vehicular traffic lanes and two middle decks for railway traffic, has been experimentally investigated for determining its aerodynamic properties. The eight flutter derivatives were determined by the Iterative Least Squares (ILS) method for this new type of four-box deck model, with two windshields of 30 mm and 50 mm height respectively. Wind tunnel experiments were performed for angles of attack α = ±6°, ±4°, ±2° and 0° and Re numbers of 4.85×105 to 6.06×105 and it was found that the four-box deck with the 50 mm windshields had a better aerodynamic performance. Also, the results showed that the installation of the windshields reduced the values of the lift coefficient CL for the negative angles attack in the range of -6° to 0°, but the drag coefficient CD increased in the positive angle of attack range. However, galloping instability was not encountered for the tested reduced wind speeds, of up to 9.8. The aerodynamic force coefficients and the flutter derivatives for the four-box deck model were consistent with the results reported for the Messina triple-box bridge deck, but were different from those reported for the twin-box bridge decks.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제29회 KOSCI SYMPOSIUM 논문집
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• pp.109-116
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• 2004

Through analysing the influence of steam flow direction on the liquid formation and motion behavior in the condenser shell side, the physical model for existing numerical simulation program of condenser is improved by introducing the correlations for flow resistance and condensation heat exchange coefficient in which the influences of steam flow direction are considered according to the available experimental data. Thus a more suitable and general condenser simulation approach is presented and a new condenser calculation program is developed. With the experimental data of a pannier- arrangement experimental condenser, the adaptability of the new condenser simulation approach is verified. General characteristics of this type of condenser are also revealed.

• 에너지공학
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• 제14권2호
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• pp.98-104
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• 2005

Pannier-arrangement condensers are usually adopted in the turbine generator units of combined cycle power plants. Optimization of operating performance and economy is an important goal, which requires accurate understanding of flow and heat transfer effects in the condenser. The tube bundle arrangement and steam flow behaviors of pannier-arrangement condensers are very different from those of common condensers. The physical model for existing numerical simulation program of condenser is refined by constructing the correlations for flow resistance and condensation heat exchange coefficient in which the influences of steam flow direction are considered according to available experimental data. The adaptability of the developed physical model and simulation program of pannier-arrangement condenser is verified with available experimental data.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.479-482
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• 2006

The absorption coefficient and backscattering properties of phytoplankton were calculated from the Mie theory. Given a simple case that phytoplankton and mineral particles are the only constitutions in seawater, the reflectance $b_b({\lambda})/[a({\lambda})+b_b({\lambda})]$was analyzed. Then the chlorophyll concentrations were estimated from remote sensing OC2 algorithm. The results show that reflectance in short wavelength region is more sensitive to the Chl variation; High mineral concentrations in seawater have significant influence on the reflectance spectrum; the existence of high mineral concentration may result in the mistake in chlorophyll estimation from OC2 algorithm.

• Fibers and Polymers
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• 제6권4호
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• pp.339-342
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• 2005

In this paper, a hand-operating method (tiled test method) of the wool-blending sample is made out, and make use of the method, the test of wool-blending bundle in different blending ratio is accomplished. According to the test data, the synthesis method of the stretch curve is worked out and the synthesis software for the typical stretch curve of wool-blending bundle is designed. Through laboratory hand-operating method, the blending fasciculus applying to fiber bundle test can be obtained in a short time. Calculation for sampling is accomplished in the article. We bring up 9 new signs to describe the characteristics of the curve behind peak for the first time: elongation behind peak (HE), elongation percentage behind peak (HEP), relative elongation rate behind peak (RHE), total break work $(W_a)$, break work behind peak (HW), break work coefficient behind peak (HWC), elongation percentage of half-load behind peak (HEL), load percentage of half-elongation behind peak (HLE), break efficiency behind peak (HEC).

• E2M - 전기 전자와 첨단 소재
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• 제1권1호
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• pp.44-53
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• 1988

In this study, PZT/PVDF composites with O-3 phase connectivity were prepared by hot pressing method, and the dielectric and piezoelectric properties as a function of PZT volume fraction were investigated. A modified cubic model was introduced to explain the influence of the PZT volume fraction on the experimentally determined dielectric constant. As A n=0.125, the measured dielectric constant values agreed with the calculated values. It was found that dielectric constant .xi.$_{33}$ and piezoelectric coefficient d$_{33}$ increased with indreasing PZT volume fraction, and hydrostatic piezoelectric figure of merit d/aub h/.g$_{h}$ was improved relative to that of the PZT single phase material.l.l.l.