• Nuclear Engineering and Technology
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• 제53권1호
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• pp.304-313
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• 2021

Nickel base Alloy X-750, which is used as fastener parts in light-water reactor (LWR), has experienced many failures by environmentally assisted cracking (EAC). In order to improve the reliability of passive components for nuclear power plants (NPP's), it is necessary to study the failure mechanism and to predict crack growth behavior by developing a probabilistic failure model. In this study, The Bayesian inference was employed to reduce the uncertainties contained in EAC modeling parameters that have been established from experiments with Alloy X-750. Corrosion fatigue crack growth rate model (FCGR) was developed by fitting into Paris' Law of measured data from the several fatigue tests conducted either in constant load or constant ΔK mode. These parameters characterizing the corrosion fatigue crack growth behavior of X-750 were successfully updated to reduce the uncertainty in the model by using the Bayesian inference method. It is demonstrated that probabilistic failure models for passive components can be developed by updating a laboratory model with field-inspection data, when crack growth rates (CGRs) are low and multiple inspections can be made prior to the component failure.

• 한국식품저장유통학회지
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• 제2권1호
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• pp.155-161
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• 1995

We examined the drying characteristics and the drying rate model equation of garlic(allium sativum L.) using computer aided convective drying. The drying chanacteristic curve of garlic divided into constant rate drying period and 2 stage of falling rate drying period. The drying rate was fairly affected by hot air temperatures during the total drying period, but air flow rates has nearly no effect on the drying rate except initial drying period. Of the several model equation, r2 values of page model equation was the highest, and the estimated drying profiles were comparatively coincided with the observed drying profiles. Page model equation was suitable to predict the drying rate and moisture content during drying of sliced garlic.

• 환경위생공학
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• 제17권1호
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• pp.69-74
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• 2002

This study explored for treatment processes by investigating the treatment efficiency and reaction mechanism through oxidation reaction using UV and $O_3$ as oxidant in compensate the wastewater containing nitrobenzene that is non biodegradable organic. Also by modeling these reactions, we try to step explanation of optimum reaction rate and reaction mechanism as the development of the computer program predictable the reaction rate by modeling the reaction. By using this model, after kinetic constant for each reaction from an experimental data is made an optimization and for hardly contribute to reaction rate in reaction kinetic equation is made an ignorance and suppose the simplified reaction mechanism, examined the propriety of computer simulation model and simplified reaction mechanism by comparing and inspecting the reaction kinetic constant and masstransfer coefficient. An investigation results for destructional treatment of nitrobenzene in the wastewater as non-biddegradable organic using UV, $O_3{\;}O_2{\;}H_2O_2-UV$ as oxidant.

• 한국압력기기공학회 논문집
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• 제4권2호
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• pp.1-6
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• 2008

Very High Temperature Gas Cooled Reactor (VHTR) has been selected as a high energy heat source for nuclear hydrogen generation. The VHTR can produce hydrogen from heat and water by using a thermo-chemical process or from heat, water, and natural gas by steam reformer technology. A co-axial double-tube primary hot gas duct (HGD) is a key component connecting the reactor pressure vessel and the intermediate heat exchanger (IHX) for the VHTR. In this study, a preliminary design analysis for the primary HGD of the nuclear hydrogen system was carried out. These preliminary design activities include a determination of the size, a strength evaluation and an appropriate material selection. The determination of the size was undertaken based on various engineering concepts, such as a constant flow velocity model, a constant flow rate model, a constant hydraulic head model, and finally a heat balanced model.

• 한국식품영양과학회지
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• 제10권1호
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• pp.53-60
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• 1981

열풍에 의한 표고버섯의 건조현상을 속도론적으로 규명하기 위해서 건조속도를 좌우하는 두 가지 인자에 대해서 그 영향을 고찰한 후 선정된 조건에서 건조곡선 및 건조속도식을 유도하였다. 일정 풍속(1.5m/sec)하에서 온도의 변화$(45{\sim}55^{\circ}C)$를 주었을 때 수분의 감소는 지수함수적으로 감소하였으며 감소율은 온도가 높을수록 더욱 높았다. 온도를 $(45^{\circ}C)$로 고정시키고 풍속의 변화$(1.0{\sim}3.1m/sec)$를 주었을 때 2m/sec까지는 풍속이 빠를수록 건조속도가 높아졌으나, 그 이상의 풍속에서는 오히려 건조속도가 감소하였다. 따라서 풍속은 2m/sec에서 가장 건조속도가 높았다. 선정된 온도 $50^{\circ}C$, 풍속 2m/sec, 습도 38-41%의 조건에서 건조곡선 및 건조속도식을 유도하여 본 결과 $X=6.94e^{-0.345t}$와, $dx/dt=-2.39e^{-0.345t}$라는 Kinetic model 이 얻어졌다.

• Journal of Pharmaceutical Investigation
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• 제20권2호
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• pp.89-95
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• 1990

Ethylcellulose-PEG 4000 film coated on core tablets was investigated as a potential drug delivery system for the controlled release of chlorpheniramine maleate (CPM). The kinetic analysis of the release data indicated that CPM release followed a diffusion-controlled model, where the quantity released per unit area is proportional to the square root of time. The effect of the film composition, CPM concentration, plasticizer concentration and CPM solubility on the release characteristics were examined. The release rate constant increased as CPM concentration increased. It also increased as the PEG 4000 content in the film increased above 10%(w/w), however, it decreased as the PEG 4000 content increased in the concentration range below 10%(w/w). The release rate constant was not affected by the coated weight on the core tablet. The film-coated tablets which contain CPM only in the coated film layer seemed to be a potential oral drug delivery system for the controlled release of CPM.

• 대한산업공학회지
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• 제17권1호
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• pp.83-94
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• 1991

This study is concerned with the scheduling problem for mixed-model assembly lines in Just-In-Time(JIT) production systems. The most important goal of the scheduling for the mixed-model assembly line in JIT production systems is to keep a constant rate of usage for every part used by the systems. In this study, we develop two heuristic algorithms able to keep a constant rate of usage for every part used by the systems in the single-level and the multi-level. In the single-level, the new algorithm generates sequence schedule by backward tracking and prevents the destruction of sequence schedule which is the weakest point of Miltenburg's algorithms. The new algorithm gives better results in total variations than the Miltenburg's algorithms. In the multi-level, the new algorithm extends the concept of the single-level algorithm and shows more efficient results in total variations than Miltenburg and Sinnamon's algorithms.

• Journal of applied mathematics & informatics
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• 제29권1_2호
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• pp.427-442
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• 2011

Calcium is a vital second messenger for signal transduction in neurons. Calcium plays an important role in almost every part of the human body but in neuronal cytosol, it is of utmost importance. In order to understand the calcium signaling mechanism in a better way a finite element model has been developed to study the flow of calcium in two dimensions with time. This model assumes EBA (Excess Buffering Approximation), incorporating all the important parameters like time, association rate, influx, buffer concentration, diffusion constant etc. Finite element method is used to obtain calcium concentration in two dimensions and numerical integration is used to compute effect of time over 2-D Calcium profile. Comparative study of calcium signaling in two dimensions with time is done with other important physiological parameters. A MATLAB program has been developed for the entire problem and simulated on an x64 machine to compute the numerical results.

• 대한안전경영과학회지
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• 제9권4호
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• pp.129-136
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• 2007

This paper considers the sequencing of products in mixed model assembly lines under Just-In-Time (JIT) systems. Under JIT systems, the most important goal for the sequencing problem is to keep a constant rate of usage every part used by the systems. The sequencing problem is solved using Genetic Algorithm Genetic Algorithm is a heuristic method which can provide a near optimal solution in real time. The performance of proposed technique is compared with existing heuristic methods in terms of solution quality. Various examples are presented and experimental results are reported to demonstrate the efficiency of the technique.

• Bulletin of the Korean Chemical Society
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• 제28권7호
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• pp.1135-1140
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• 2007

Pseudo-first-order rate constants (kobs) for the reaction of N-benzylphthalimide (NBPT) with HO- have been determined at 2.0 × 10?4 M NBPT, 1.0 × 10?3 and 2.0 × 10?3 M NaOH as well as varying concentrations of cetyltrimethylammonium bromide ([CTABr]T = 0.0-1.7 × 10?1 M). The effects of [CTABr]T ? CMC (with CMC representing the critical micelle concentration of CTABr) on kobs have been analyzed in terms of Berezin's pseudophase (BPP) model and pseudophase ion-exchange (PIE) model. Although both models give the best observed data fit with least-squares values not significantly different from each other, the calculated values of KS from BPP model appear to be more reliable compared to those from PIE model because the values of KS from BPP model are similar to the corresponding KS values determined spectrophotometrically.