• 한국자동차공학회논문집
• /
• 제14권6호
• /
• pp.127-136
• /
• 2006

Prediction of diesel particulate filtration is typically made by virtue of modeling of particulate matter(PM) collection. The model is closed with filtration parameters reflecting all small scale phenomena associated with PM trapping, and these parameters are to be traced back by inversely analyzing large-scale empirical data-the pressure drop histories. Included are soot cake permeability, soot cake density, soot density in the porous filter wall, and percolation constant. In the present study, a series of single channel DPF experiment is conducted, pressure histories are inversely analyzed, and the essential filtration parameters are deducted by DPF filtration model formulated with non-linear description of soot cake regression. Sensitivity analyses of model parameters are also made. Results showed that filtration transients are significantly altered by the extent of percolation constant, and the soot density in the porous filter wall is controlling the filtration qualities in deep-bed filtration regime. In addition, effect of soot particle size on filtration quality is distinct in a period of soot cake regime.

• KSBB Journal
• /
• 제10권1호
• /
• pp.97-104
• /
• 1995

1. 돼지 성장호르몬을 연간 6000Kg을 생산하는 공장의 공정 설계를 Macintosh PC를 사용한 Bio D Designer를 이용해서 공정모사를 해 보았다. 각 단 위공정의 계산자를 정하기 위한 계산을 가정과 플라 스크배양의 결과를 이용하여 up-stream을 설계하고, downstream에서는 25%의 분리정제 수율을 가 정하고 전체공정을 설계하였다. 2. 경제성 분석에 의하연 돼지 성장호르몬의 dose 당 $ 2.00로 할 때 투자상환율 (return on invest­m ment, ROI)이 일 년에 104%이었으며, 투자금액의 상환에 걸리는 시간은 약 1년(0.96\건)이 걸리는 것으로 나왔다. 3. Sensitivity분석에 의하면 투자상환율은 돼 지 성장호르몬의 수율, 가격, 사용량 및 시장잠식율 순서의 변수에 의해 결정되는 것을 알 수 있었다.

• The Plant Pathology Journal
• /
• 제33권2호
• /
• pp.118-124
• /
• 2017

Bell pepper is an economically important crop worldwide; however, production is restricted by a number of fungal diseases that cause significant yield loss. Chemical control is the most common approach adopted by growers to manage a number of these diseases. Monitoring for the development to resistance to fungicides in pathogenic fungal populations is central to devising integrated pest management strategies. Two fungal species, Fusarium incarnatum-equiseti species complex (FIESC) and Colletotrichum truncatum are important pathogens of bell pepper in Trinidad. This study was carried out to determine the sensitivity of 71 isolates belonging to these two fungal species to fungicides with different modes of action based on in vitro bioassays. There was no significant difference in log effective concentration required to achieve 50% colony growth inhibition ($LogEC_{50}$) values when field location and fungicide were considered for each species separately based on ANOVA analyses. However, the $LogEC_{50}$ value for the Aranguez-Antracol locationfungicide combination was almost twice the value for the Maloney/Macoya-Antracol location-fungicide combination regardless of fungal species. $LogEC_{50}$ values for Benomyl fungicide was also higher for C. truncatum isolates than for FIESC isolates and for any other fungicide. Cropping practices in these locations may explain the fungicide sensitivity data obtained.

• Journal of Microbiology and Biotechnology
• /
• 제4권1호
• /
• pp.13-19
• /
• 1994

A model equation to describe the plasmid instability in recombinant Escherichia coli fermentation is proposed. The equation allows one to estimate easily the two model parameters; (1) the difference in the specific growth rates between plasmid-free cells and plasmid-harboring cells ($\delta$), and (2) the probability of plasmid loss by plasmid-harboring cells ($\rho$). The estimated values of $\delta and \rho$ were in the range of 0.02-0.07 and $10^{-3}-10^{-5}$, respectively, and were strongly dependent on the dilution rate. As another parameter, the ratio of specific growth rates of plasmid-free cells and plasmid-harboring cells ($\alha$) was calculated and the result showed the highest value of 1.28 at the lowest dilution rate of 0.075 $hr^{-l}$, examined in this work. By the sensitivity analyses on the estimates of $\delta and \rho$, it was found that the growth rate difference ($\delta$) affected the plasmid instability more seriously than the probability of plasmid loss ($\rho$). Furthermore, the profound instability of plasmid at low dilution rate could be explained by the high values of $\alpha and \rho$.

• Nuclear Engineering and Technology
• /
• 제46권3호
• /
• pp.343-352
• /
• 2014

Uncertainty and sensitivity analyses with respect to nuclear data are performed with depletion calculations for BWR and PWR fuel assemblies specified in the framework of the UAM-LWR Benchmark Phase II. For this, the GRS sampling based tool XSUSA is employed together with the TRITON depletion sequences from the SCALE 6.1 code system. Uncertainties for multiplication factors and nuclide inventories are determined, as well as the main contributors to these result uncertainties by calculating importance indicators. The corresponding neutron transport calculations are performed with the deterministic discrete-ordinates code NEWT. In addition, the Monte Carlo code KENO in multi-group mode is used to demonstrate a method with which the number of neutron histories per calculation run can be substantially reduced as compared to that in a calculation for the nominal case without uncertainties, while uncertainties and sensitivities are obtained with almost the same accuracy.

• 품질경영학회지
• /
• 제39권4호
• /
• pp.507-515
• /
• 2011

MIL-HDBK-217 has played a pivotal role in reliability prediction of electronic equipments for more than 30 years. Recently, RIAC developed a new methodology $217Plus^{TM}$which officially replaces MIL-HDBK-217. Sensitivity analysis of the 217Plus component models to various parameters has been performed and meaningful observations have been drawn in this study. We first briefly reviewed the $217Plus^{TM}$ methodolog and compared it with the conventional model, MIL-HDBK-217. We then performed sensitivity analysis $217Plus^{TM}$ component models to various parameters. Based on the six parameters and an orthogonal array selected, we have performed indepth analyses concerning parameter effects on the model. Our result indicates that, among various parameters, operating temperature and temperature rise during operation have the most significant impacts on the life of a component, and thus a design robust to high temperature is the most importantly required. Next, year of manufacture, duty cycle, and voltage stress are weaker but may be significant when they are in heavy load conditions. Although our study is restricted to a specific type of diodes, the results are still valid to other cases. The results in this study not only figure out the behavior of the predicted failure rate as a function of parameters but provide meaningful guidelines for practical applications.

• 대한토목학회논문집
• /
• 제5권3호
• /
• pp.137-144
• /
• 1985

본 연구에서는 구조물 최적 설계시 필수적인 설계민감도 해석을 의사변분법을 도입하여 유한차원 구조물에 적용함으로써 구조물 최적설계를 기존의 방법보다 훨씬 간편하게 할 수 있음을 보인다. 정하중하에서 제약조건의 주종을 이루고 있는 변위 및 응력의 제약조건에 대하여 설계민감도 해석 및 그 수치해를 구하며 나아가 최적화 알고리리즘을 사용하여 최적설계가 효율적으로 수행됨을 입증한다. 유한차원 구조물인 트러스의 적당한 경계조건, 하중조건 및 제약조건하에서 구조물의 무게를 최소화 시키는 최적설계 문제를 고려한다.

• Smart Structures and Systems
• /
• 제22권4호
• /
• pp.441-457
• /
• 2018

Characteristic parameter values of seismic isolators deviate from their nominal design values due to uncertainties and/or errors in their material properties and element dimensions, etc. Deviations may increase over service life due to environmental effects and service conditions. For accurate evaluation of the seismic safety level, all such effects, which would result in deviations in the structural response, need to be taken into account. In this study, the sensitivity of the probability of failure of the structures equipped with nonlinear base isolation systems to the uncertainties in various isolation system characteristic parameters is investigated in terms of various isolation system and superstructure response parameters in the context of a realistic three-dimensional base-isolated building model via Monte Carlo Simulations. The inherent record-to-record variability nature of the earthquake ground motions is also taken into account by carrying out analyses for a large number of ground motion records which are classified as those with and without forward-directivity effects. Two levels of nominal isolation periods each with three different levels of uncertainty are considered. Comparative plots of cumulative distribution functions and related statistical evaluation presented here portray the potential extent of the deviation of the structural response parameters resulting from the uncertainties and the uncertainty levels considered, which is expected to be useful for practicing engineers in evaluating isolator test results for their projects.

• 대한기계학회논문집
• /
• 제16권2호
• /
• pp.236-247
• /
• 1992

Optimization has been developed to minimize the cost function while satisfying constraints. Nonlinear Programming method is used as a tool for the optimization. Usually, cost and constraint function calculations are required in the engineering applications, but those calculations are extremely expensive. Especially, the function and sensitivity analyses cause a bottleneck in structural optimization which utilizes the Finite Element Method. Also, when the functions are quite noisy, the informations do not carry out proper role in the optimization process. An algorithm called "Second-order Approximation Method" has been proposed to overcome the difficulties recently. The cost and constraint functions are approximated by the second-order Taylor series expansion on a nominal points in the algorithm. An optimal design problem is defined with the approximated functions and the approximated problem is solved by a nonlinear programming numerical algorithm. The solution is included in a candidate point set which is evaluated for a new nominal point. Since the functions are approximated only by the function values, sensitivity informations are not needed. One-dimensional line search is unnecessary due to the fact that the nonlinear algorithm handles the approximated functions. In this research, the method is analyzed and the performance is evaluated. Several mathematical problems are created and some standard engineering problems are selected for the evaluation. Through numerical results, applicabilities of the algorithm to large scale and complex problems are presented.presented.

• 한국안전학회지
• /
• 제22권6호
• /
• pp.27-34
• /
• 2007

Static or dynamic elastomeric O-ring seals are installed between joining parts, and play key roles of high pressure-tightening. Sealing performance and structural safety of the O-ring are dependent on groove design, plain diameter, squeeze and applications such as pressure and temperature. In this study, to solve O-ring problem squeezed and highly pressurized under laterally one-sided constrained condition, hyperelastic FE analyses are performed, and FE results are compared with measured ones by computer-aided tomography, deformed shape and extrusion depth of the O-ring. Through the comparisons, FE analysis technique was verified. In order to evaluate design sensitivity, Taguchi method was used to select FE analysis cases. Adjustment parameters are clearance gap, groove comer radius, plain diameter and squeeze. By means of verified FE analysis technique, it has been analysed how the parameters have effects on contact stress fields, internal stress fields, and extrusion depths. Sealing performance has been evaluated based on contact stress fields and contact widths, and structural safety on internal stress and strain, extrusion lengths.