• International Journal of Fluid Machinery and Systems
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• v.9 no.4
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• pp.362-369
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• 2016

The shock-free inflow criterion applied in the development of two-dimensional cascade for turbomachinery design. The developed cascade analysis with potential flow calculation through a panel method has been used to determine the shock-free inflow condition. The combination between cascade analysis and PSO (particle swarm optimization) algorithm provides an opportunity to develop a diagram of a two-dimensional parameter cascade at various airfoil shapes. Analytical equations have been derived from the diagram that will facilitate the turbomachinery designer in applying the shock-free inflow criterion on their developed cascade. This method has been used to develop the very low head axial hydraulic turbine and provides excellent results of numerical and actual prototype performances.

• Archives of Pharmacal Research
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• v.15 no.2
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• pp.109-114
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• 1992

For the risk assessment of human exposure to volatile halogenated hydrocarbons, a dynamic purge trap/on-column cryofocusing method using capillary gas chromatograph-$^{63}Ni$ electron capture detector and thermal desorption unit was applied to analyze the free forms, metabolites of 1, 1, 2-trichloroethylene and 1, 1, 2, 2-tetrachloroethylene. The urine sample was diluted with distilled water, hydrolyzed and sealed. Then the inert gas was infused to purge out free 1, 1, 2-trichloroethylene, free 1, 1, 2, 2-tetrachloroethylene and urichloroethanol. These compounds were trapped to $Tenax^R$ / GC-gas trap device throughout clean up tube. Being undertectable to gas chromatograph directly, trichloroacetic acid was methyl esterificated and trapped in the manner above mentioned. The optimal incubation time to get best recovery of methyl ester was 4 hours at $60^circ$C. The concentrations of free volatile halogenated hydrocarbons and their metabolites in urine were obtained of free volatile halogenated hydrocarbons and their metabolites in urine were obtained from 5 healthy volunteers. This analytical method is expected to make the biological monitoring more precise and convenient.

• Journal of Magnetics
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• v.18 no.3
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• pp.283-288
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• 2013

This paper presents structural topology optimization that is being applied for the design of electromagnetic vibration energy harvester. The design goal is to maximize the root-mean-square value of output voltage generated by external vibration leading structures. To calculate the output voltage, the magnetic field analysis is performed by using the finite element method, and the obtained magnetic flux linkage is interpolated by using Lagrange polynomials. To achieve the design goal, permanent magnet is designed by using topology optimization. The analytical design sensitivity is derived from the adjoint variable method, and the formulated optimization problem is solved through the method of moving asymptotes (MMA). As optimization results, the optimal location and shape of the permanent magnet are provided when the magnetization direction is fixed. In addition, the optimization results including the design of magnetization direction are provided.

• Coupled systems mechanics
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• v.10 no.6
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• pp.491-507
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• 2021

The aim of this paper is to conduct a hydrodynamic analysis of fluid flow over different weir types using the analytical solution, the physical model taken from another article, and numericalsimulations through the Smoothed particle hydrodynamic method (SPH) using the compiled DualSPHysics source code. The paper covers the field of real fluid dynamics that includes a description of different proposed types of weirs in various flow regimes and the optimal solution for the most efficiency structure shape. A detailed presentation of the method, the structure and it's characteristics are included. Apart from the single stepped weir, two other weir types are proposed: a Divided type and a Downstream slopped type. All of them are modeled using the SPH method.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.3
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• pp.332-340
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• 2016

A design optimization is performed for the double-bolted joint in cylindrical composite structures by using a simplified analytical method. This method uses failure criteria for the major failure modes of the bolted composite joint. For the double-bolted joint with a zigzag arrangement, it is necessary to consider an interaction effect between the bolt arrays. This paper proposes another failure mode which is determined by angle and distance between two bolts in different arrays and define a failure criterion for the failure mode. The optimal design for the double-bolted joint is carried out by considering the interactive net-tension failure mode. The genetic algorithm (GA) is adopted to determine the optimized parameters; bolt spacing, edge distance, and stacking sequence of the composite laminate. A purpose of the design optimization is to maximize the burst pressure of the cylindrical structures by ensuring structural integrity. Also, a progressive failure analysis (PFA) is performed to verify the results of the optimal design for the double-bolted joint. In PFA, Hashin 3D failure criterion is used to determine the ply that would fail. A stiffness reduction model is then used to reduce the stiffness of the failed ply for the corresponding failure mode.

• Journal of the Korean Institute of Telematics and Electronics
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• v.10 no.1
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• pp.1-8
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• 1973

It is often difficult, or almost impossible, in most cases to obtain the optimal solution to the non-linear control systems by analytical method. In this paper, the authors have treated with the technique of parameteric adaptation which is introduced into the performance index, in order to circumvent the difficulties arising in seal.ch of optimal policy for the non-linear feedback control systems. This approach is shown to provide the advantage of making it possible to design the non-linear feedback control system even if the design specifications are not completely discribed in mathematical form. This is fundamentally due to a certain degree of freedoln in design, which this method allows the designer in establishing the performance index. The effectiveness and feasibilities of this concept are demonstrated by working out some illustrative examples with the performance index of integral quadratic form.

• Analytical Science and Technology
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• v.11 no.4
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• pp.243-247
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• 1998

Cisplatin is a platinum-containing antitumor agent with nephrotoxic and neurotoxic side effects. An analytical method for measuring cisplatin in plasma by FAAS was developed, which is rapid, simple and need no sample preparation. The linearity test of calibration curve in the range of 20~1000 ng/mL showed good correlation coefficient of r=0.999. The result of accuracy test appeared to be relative standard deviation of < 5.0% at concentration range from 50 to 1000 ng/mL. When $200{\mu}L$ of plasma was used, detection limit was 10 ng/mL. Therefore, it can be applied for the monitoring in plasma for optimal condition of treatment and reduce of toxicity.

• Mass Spectrometry Letters
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• v.13 no.3
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• pp.58-83
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• 2022

We developed analytical methods using high performance chromatography (HPLC) and liquid chromatography tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of 80 unapproved compounds in dietary supplements. The target compounds for analysis were unapproved ingredients (e.g., pharmaceuticals) that have potential adverse effects on consumers owing to accidental misuse, overuse, and interaction with other medication in dietary supplement. Two analytical methods were tested to identify the optimal validation results according to AOAC guideline. As a result, limit of quantification (LOQ) was 0.14-0.5 ㎍ mL^-1; linearity (r²) was ≥ 0.99; accuracy (expressed as recovery) was 78.9-114%; precision (relative standard deviation) was ≤ 4.28% in the HPLC method. In the LC-MS/MS method, LOQ was 0.01-2 ng mL^-1, linearity (r²) was ≥0.98, accuracy was 71.7-119%; precision was ≤ 12.5%. The developed methods were applied to 51 dietary supplements collected from 2019 to 2021 through MFDS alert system. Based on our previous monitoring study, major compounds were icariin, sibutramine, yohimbine, sildenafil, tadalafil, sennosides (A, B), cascarosides (A, B, C, D), and phenolphthalein. In this study, we re-analyzed samples of detected compounds, and evaluated the statistical difference using Bland-Altman analysis to compare two analytical approaches between HPLC and LC-MS/MS. These results showed a good agreement between two methods that can be used to monitor the unapproved ingredients in dietary supplements. The developed two methods are complementarily suitable for monitoring the adulteration of 80 unapproved compounds in dietary supplements.

• Journal of Food Hygiene and Safety
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• v.33 no.2
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• pp.110-117
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• 2018

The aim of this study was to develop an analytical method for the quantification of diazepam residues in fishery products, using liquid and gas chromatography-tandem mass spectrometry (LC-MS/MS and GC-MS/MS). The sample utilized in the study was extracted from the fish sample (crucian carp) using 0.1% formic acid in acetonitrile. For the utilization of the purification process, the dispersive solid phase extraction (dSPE) was used for LC-MS/MS, dSPE and SPE was used for GC-MS/MS, respectively. To be sure, the standard calibration curves showed a good linearity as the noted correlation coefficients, $r^2$ was > 0.99. The average recoveries for accuracy ranged in 99.8~124% for the samples which were fortified at three different levels (0.001, 0.002 and 0.010 mg/kg). The correlation coefficient for the precision effect was measured at a range of 4.01~11.8%. The limit of detection (LOD) for the diazepam analysis was 0.0004 mg/kg, and the limit of the quantification (LOQ) was 0.001 mg/kg. The proposed analytical method was characterized with a high accuracy and acceptable sensitivity to meet the established Codex Alimentarius Commission (CAC/GL71-2009) guideline requirements. We therefore established the optimal analysis method for the determination of diazepam in the fishery products using LC-MS/MS and GC-MS/MS. It would be applicable to analyze the diazepam residues in fishery products in further studies on this subject.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.4
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• pp.353-358
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• 2011

In this paper, we describe a process for optimally designing a ring-type permanent magnet thrust bearing. The bearing consists of two sets of permanent magnet rings. One set is located inside the other set. An axial offset between the two sets creates axial force, which results in a thrust bearing function. In order to realize an optimal design of the bearing where the required load capacity of the bearing is achieved with the least magnet volume, we derived analytical design equations by adopting the equivalent current sheet (ECS) method. We considered the following two types of magnet arrays: axial arrays and Halbach arrays. These two types of arrays are optimized using the analytical design equations. The results of the optimization are verified using three dimensional (3D) finite element analyses (FEA). The results show that the Halbach array can achieve the required load capacity with less amount of permanent magnet than the axial array does. The efficacy of the ECS method is also verified by using 3D FEA. It is found that the accuracy of ECS method is more sensitive to the underlying assumptions for the Halbach array than for the axial array.